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authorDave Kleikamp <shaggy@austin.ibm.com>2006-10-11 01:20:57 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-11 11:14:15 -0700
commit470decc613ab2048b619a01028072d932d9086ee (patch)
tree5268576f5099040db94b8e984983c0bb28b2a9a7 /fs/jbd2
parent02ea2104c55b625cf5b5d9ba8586a4fc17920f5c (diff)
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[PATCH] jbd2: initial copy of files from jbd
This is a simple copy of the files in fs/jbd to fs/jbd2 and /usr/incude/linux/[ext4_]jbd.h to /usr/include/[ext4_]jbd2.h Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/jbd2')
-rw-r--r--fs/jbd2/Makefile7
-rw-r--r--fs/jbd2/checkpoint.c697
-rw-r--r--fs/jbd2/commit.c911
-rw-r--r--fs/jbd2/journal.c2072
-rw-r--r--fs/jbd2/recovery.c592
-rw-r--r--fs/jbd2/revoke.c703
-rw-r--r--fs/jbd2/transaction.c2080
7 files changed, 7062 insertions, 0 deletions
diff --git a/fs/jbd2/Makefile b/fs/jbd2/Makefile
new file mode 100644
index 00000000000..54aca4868a3
--- /dev/null
+++ b/fs/jbd2/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for the linux journaling routines.
+#
+
+obj-$(CONFIG_JBD) += jbd.o
+
+jbd-objs := transaction.o commit.o recovery.o checkpoint.o revoke.o journal.o
diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
new file mode 100644
index 00000000000..0208cc7ac5d
--- /dev/null
+++ b/fs/jbd2/checkpoint.c
@@ -0,0 +1,697 @@
+/*
+ * linux/fs/checkpoint.c
+ *
+ * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
+ *
+ * Copyright 1999 Red Hat Software --- All Rights Reserved
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * Checkpoint routines for the generic filesystem journaling code.
+ * Part of the ext2fs journaling system.
+ *
+ * Checkpointing is the process of ensuring that a section of the log is
+ * committed fully to disk, so that that portion of the log can be
+ * reused.
+ */
+
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/jbd.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+
+/*
+ * Unlink a buffer from a transaction checkpoint list.
+ *
+ * Called with j_list_lock held.
+ */
+static inline void __buffer_unlink_first(struct journal_head *jh)
+{
+ transaction_t *transaction = jh->b_cp_transaction;
+
+ jh->b_cpnext->b_cpprev = jh->b_cpprev;
+ jh->b_cpprev->b_cpnext = jh->b_cpnext;
+ if (transaction->t_checkpoint_list == jh) {
+ transaction->t_checkpoint_list = jh->b_cpnext;
+ if (transaction->t_checkpoint_list == jh)
+ transaction->t_checkpoint_list = NULL;
+ }
+}
+
+/*
+ * Unlink a buffer from a transaction checkpoint(io) list.
+ *
+ * Called with j_list_lock held.
+ */
+static inline void __buffer_unlink(struct journal_head *jh)
+{
+ transaction_t *transaction = jh->b_cp_transaction;
+
+ __buffer_unlink_first(jh);
+ if (transaction->t_checkpoint_io_list == jh) {
+ transaction->t_checkpoint_io_list = jh->b_cpnext;
+ if (transaction->t_checkpoint_io_list == jh)
+ transaction->t_checkpoint_io_list = NULL;
+ }
+}
+
+/*
+ * Move a buffer from the checkpoint list to the checkpoint io list
+ *
+ * Called with j_list_lock held
+ */
+static inline void __buffer_relink_io(struct journal_head *jh)
+{
+ transaction_t *transaction = jh->b_cp_transaction;
+
+ __buffer_unlink_first(jh);
+
+ if (!transaction->t_checkpoint_io_list) {
+ jh->b_cpnext = jh->b_cpprev = jh;
+ } else {
+ jh->b_cpnext = transaction->t_checkpoint_io_list;
+ jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
+ jh->b_cpprev->b_cpnext = jh;
+ jh->b_cpnext->b_cpprev = jh;
+ }
+ transaction->t_checkpoint_io_list = jh;
+}
+
+/*
+ * Try to release a checkpointed buffer from its transaction.
+ * Returns 1 if we released it and 2 if we also released the
+ * whole transaction.
+ *
+ * Requires j_list_lock
+ * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
+ */
+static int __try_to_free_cp_buf(struct journal_head *jh)
+{
+ int ret = 0;
+ struct buffer_head *bh = jh2bh(jh);
+
+ if (jh->b_jlist == BJ_None && !buffer_locked(bh) && !buffer_dirty(bh)) {
+ JBUFFER_TRACE(jh, "remove from checkpoint list");
+ ret = __journal_remove_checkpoint(jh) + 1;
+ jbd_unlock_bh_state(bh);
+ journal_remove_journal_head(bh);
+ BUFFER_TRACE(bh, "release");
+ __brelse(bh);
+ } else {
+ jbd_unlock_bh_state(bh);
+ }
+ return ret;
+}
+
+/*
+ * __log_wait_for_space: wait until there is space in the journal.
+ *
+ * Called under j-state_lock *only*. It will be unlocked if we have to wait
+ * for a checkpoint to free up some space in the log.
+ */
+void __log_wait_for_space(journal_t *journal)
+{
+ int nblocks;
+ assert_spin_locked(&journal->j_state_lock);
+
+ nblocks = jbd_space_needed(journal);
+ while (__log_space_left(journal) < nblocks) {
+ if (journal->j_flags & JFS_ABORT)
+ return;
+ spin_unlock(&journal->j_state_lock);
+ mutex_lock(&journal->j_checkpoint_mutex);
+
+ /*
+ * Test again, another process may have checkpointed while we
+ * were waiting for the checkpoint lock
+ */
+ spin_lock(&journal->j_state_lock);
+ nblocks = jbd_space_needed(journal);
+ if (__log_space_left(journal) < nblocks) {
+ spin_unlock(&journal->j_state_lock);
+ log_do_checkpoint(journal);
+ spin_lock(&journal->j_state_lock);
+ }
+ mutex_unlock(&journal->j_checkpoint_mutex);
+ }
+}
+
+/*
+ * We were unable to perform jbd_trylock_bh_state() inside j_list_lock.
+ * The caller must restart a list walk. Wait for someone else to run
+ * jbd_unlock_bh_state().
+ */
+static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
+ __releases(journal->j_list_lock)
+{
+ get_bh(bh);
+ spin_unlock(&journal->j_list_lock);
+ jbd_lock_bh_state(bh);
+ jbd_unlock_bh_state(bh);
+ put_bh(bh);
+}
+
+/*
+ * Clean up transaction's list of buffers submitted for io.
+ * We wait for any pending IO to complete and remove any clean
+ * buffers. Note that we take the buffers in the opposite ordering
+ * from the one in which they were submitted for IO.
+ *
+ * Called with j_list_lock held.
+ */
+static void __wait_cp_io(journal_t *journal, transaction_t *transaction)
+{
+ struct journal_head *jh;
+ struct buffer_head *bh;
+ tid_t this_tid;
+ int released = 0;
+
+ this_tid = transaction->t_tid;
+restart:
+ /* Did somebody clean up the transaction in the meanwhile? */
+ if (journal->j_checkpoint_transactions != transaction ||
+ transaction->t_tid != this_tid)
+ return;
+ while (!released && transaction->t_checkpoint_io_list) {
+ jh = transaction->t_checkpoint_io_list;
+ bh = jh2bh(jh);
+ if (!jbd_trylock_bh_state(bh)) {
+ jbd_sync_bh(journal, bh);
+ spin_lock(&journal->j_list_lock);
+ goto restart;
+ }
+ if (buffer_locked(bh)) {
+ atomic_inc(&bh->b_count);
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ wait_on_buffer(bh);
+ /* the journal_head may have gone by now */
+ BUFFER_TRACE(bh, "brelse");
+ __brelse(bh);
+ spin_lock(&journal->j_list_lock);
+ goto restart;
+ }
+ /*
+ * Now in whatever state the buffer currently is, we know that
+ * it has been written out and so we can drop it from the list
+ */
+ released = __journal_remove_checkpoint(jh);
+ jbd_unlock_bh_state(bh);
+ journal_remove_journal_head(bh);
+ __brelse(bh);
+ }
+}
+
+#define NR_BATCH 64
+
+static void
+__flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count)
+{
+ int i;
+
+ ll_rw_block(SWRITE, *batch_count, bhs);
+ for (i = 0; i < *batch_count; i++) {
+ struct buffer_head *bh = bhs[i];
+ clear_buffer_jwrite(bh);
+ BUFFER_TRACE(bh, "brelse");
+ __brelse(bh);
+ }
+ *batch_count = 0;
+}
+
+/*
+ * Try to flush one buffer from the checkpoint list to disk.
+ *
+ * Return 1 if something happened which requires us to abort the current
+ * scan of the checkpoint list.
+ *
+ * Called with j_list_lock held and drops it if 1 is returned
+ * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
+ */
+static int __process_buffer(journal_t *journal, struct journal_head *jh,
+ struct buffer_head **bhs, int *batch_count)
+{
+ struct buffer_head *bh = jh2bh(jh);
+ int ret = 0;
+
+ if (buffer_locked(bh)) {
+ atomic_inc(&bh->b_count);
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ wait_on_buffer(bh);
+ /* the journal_head may have gone by now */
+ BUFFER_TRACE(bh, "brelse");
+ __brelse(bh);
+ ret = 1;
+ } else if (jh->b_transaction != NULL) {
+ transaction_t *t = jh->b_transaction;
+ tid_t tid = t->t_tid;
+
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ log_start_commit(journal, tid);
+ log_wait_commit(journal, tid);
+ ret = 1;
+ } else if (!buffer_dirty(bh)) {
+ J_ASSERT_JH(jh, !buffer_jbddirty(bh));
+ BUFFER_TRACE(bh, "remove from checkpoint");
+ __journal_remove_checkpoint(jh);
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ journal_remove_journal_head(bh);
+ __brelse(bh);
+ ret = 1;
+ } else {
+ /*
+ * Important: we are about to write the buffer, and
+ * possibly block, while still holding the journal lock.
+ * We cannot afford to let the transaction logic start
+ * messing around with this buffer before we write it to
+ * disk, as that would break recoverability.
+ */
+ BUFFER_TRACE(bh, "queue");
+ get_bh(bh);
+ J_ASSERT_BH(bh, !buffer_jwrite(bh));
+ set_buffer_jwrite(bh);
+ bhs[*batch_count] = bh;
+ __buffer_relink_io(jh);
+ jbd_unlock_bh_state(bh);
+ (*batch_count)++;
+ if (*batch_count == NR_BATCH) {
+ spin_unlock(&journal->j_list_lock);
+ __flush_batch(journal, bhs, batch_count);
+ ret = 1;
+ }
+ }
+ return ret;
+}
+
+/*
+ * Perform an actual checkpoint. We take the first transaction on the
+ * list of transactions to be checkpointed and send all its buffers
+ * to disk. We submit larger chunks of data at once.
+ *
+ * The journal should be locked before calling this function.
+ */
+int log_do_checkpoint(journal_t *journal)
+{
+ transaction_t *transaction;
+ tid_t this_tid;
+ int result;
+
+ jbd_debug(1, "Start checkpoint\n");
+
+ /*
+ * First thing: if there are any transactions in the log which
+ * don't need checkpointing, just eliminate them from the
+ * journal straight away.
+ */
+ result = cleanup_journal_tail(journal);
+ jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
+ if (result <= 0)
+ return result;
+
+ /*
+ * OK, we need to start writing disk blocks. Take one transaction
+ * and write it.
+ */
+ spin_lock(&journal->j_list_lock);
+ if (!journal->j_checkpoint_transactions)
+ goto out;
+ transaction = journal->j_checkpoint_transactions;
+ this_tid = transaction->t_tid;
+restart:
+ /*
+ * If someone cleaned up this transaction while we slept, we're
+ * done (maybe it's a new transaction, but it fell at the same
+ * address).
+ */
+ if (journal->j_checkpoint_transactions == transaction &&
+ transaction->t_tid == this_tid) {
+ int batch_count = 0;
+ struct buffer_head *bhs[NR_BATCH];
+ struct journal_head *jh;
+ int retry = 0;
+
+ while (!retry && transaction->t_checkpoint_list) {
+ struct buffer_head *bh;
+
+ jh = transaction->t_checkpoint_list;
+ bh = jh2bh(jh);
+ if (!jbd_trylock_bh_state(bh)) {
+ jbd_sync_bh(journal, bh);
+ retry = 1;
+ break;
+ }
+ retry = __process_buffer(journal, jh, bhs,&batch_count);
+ if (!retry && lock_need_resched(&journal->j_list_lock)){
+ spin_unlock(&journal->j_list_lock);
+ retry = 1;
+ break;
+ }
+ }
+
+ if (batch_count) {
+ if (!retry) {
+ spin_unlock(&journal->j_list_lock);
+ retry = 1;
+ }
+ __flush_batch(journal, bhs, &batch_count);
+ }
+
+ if (retry) {
+ spin_lock(&journal->j_list_lock);
+ goto restart;
+ }
+ /*
+ * Now we have cleaned up the first transaction's checkpoint
+ * list. Let's clean up the second one
+ */
+ __wait_cp_io(journal, transaction);
+ }
+out:
+ spin_unlock(&journal->j_list_lock);
+ result = cleanup_journal_tail(journal);
+ if (result < 0)
+ return result;
+ return 0;
+}
+
+/*
+ * Check the list of checkpoint transactions for the journal to see if
+ * we have already got rid of any since the last update of the log tail
+ * in the journal superblock. If so, we can instantly roll the
+ * superblock forward to remove those transactions from the log.
+ *
+ * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
+ *
+ * Called with the journal lock held.
+ *
+ * This is the only part of the journaling code which really needs to be
+ * aware of transaction aborts. Checkpointing involves writing to the
+ * main filesystem area rather than to the journal, so it can proceed
+ * even in abort state, but we must not update the journal superblock if
+ * we have an abort error outstanding.
+ */
+
+int cleanup_journal_tail(journal_t *journal)
+{
+ transaction_t * transaction;
+ tid_t first_tid;
+ unsigned long blocknr, freed;
+
+ /* OK, work out the oldest transaction remaining in the log, and
+ * the log block it starts at.
+ *
+ * If the log is now empty, we need to work out which is the
+ * next transaction ID we will write, and where it will
+ * start. */
+
+ spin_lock(&journal->j_state_lock);
+ spin_lock(&journal->j_list_lock);
+ transaction = journal->j_checkpoint_transactions;
+ if (transaction) {
+ first_tid = transaction->t_tid;
+ blocknr = transaction->t_log_start;
+ } else if ((transaction = journal->j_committing_transaction) != NULL) {
+ first_tid = transaction->t_tid;
+ blocknr = transaction->t_log_start;
+ } else if ((transaction = journal->j_running_transaction) != NULL) {
+ first_tid = transaction->t_tid;
+ blocknr = journal->j_head;
+ } else {
+ first_tid = journal->j_transaction_sequence;
+ blocknr = journal->j_head;
+ }
+ spin_unlock(&journal->j_list_lock);
+ J_ASSERT(blocknr != 0);
+
+ /* If the oldest pinned transaction is at the tail of the log
+ already then there's not much we can do right now. */
+ if (journal->j_tail_sequence == first_tid) {
+ spin_unlock(&journal->j_state_lock);
+ return 1;
+ }
+
+ /* OK, update the superblock to recover the freed space.
+ * Physical blocks come first: have we wrapped beyond the end of
+ * the log? */
+ freed = blocknr - journal->j_tail;
+ if (blocknr < journal->j_tail)
+ freed = freed + journal->j_last - journal->j_first;
+
+ jbd_debug(1,
+ "Cleaning journal tail from %d to %d (offset %lu), "
+ "freeing %lu\n",
+ journal->j_tail_sequence, first_tid, blocknr, freed);
+
+ journal->j_free += freed;
+ journal->j_tail_sequence = first_tid;
+ journal->j_tail = blocknr;
+ spin_unlock(&journal->j_state_lock);
+ if (!(journal->j_flags & JFS_ABORT))
+ journal_update_superblock(journal, 1);
+ return 0;
+}
+
+
+/* Checkpoint list management */
+
+/*
+ * journal_clean_one_cp_list
+ *
+ * Find all the written-back checkpoint buffers in the given list and release them.
+ *
+ * Called with the journal locked.
+ * Called with j_list_lock held.
+ * Returns number of bufers reaped (for debug)
+ */
+
+static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
+{
+ struct journal_head *last_jh;
+ struct journal_head *next_jh = jh;
+ int ret, freed = 0;
+
+ *released = 0;
+ if (!jh)
+ return 0;
+
+ last_jh = jh->b_cpprev;
+ do {
+ jh = next_jh;
+ next_jh = jh->b_cpnext;
+ /* Use trylock because of the ranking */
+ if (jbd_trylock_bh_state(jh2bh(jh))) {
+ ret = __try_to_free_cp_buf(jh);
+ if (ret) {
+ freed++;
+ if (ret == 2) {
+ *released = 1;
+ return freed;
+ }
+ }
+ }
+ /*
+ * This function only frees up some memory
+ * if possible so we dont have an obligation
+ * to finish processing. Bail out if preemption
+ * requested:
+ */
+ if (need_resched())
+ return freed;
+ } while (jh != last_jh);
+
+ return freed;
+}
+
+/*
+ * journal_clean_checkpoint_list
+ *
+ * Find all the written-back checkpoint buffers in the journal and release them.
+ *
+ * Called with the journal locked.
+ * Called with j_list_lock held.
+ * Returns number of buffers reaped (for debug)
+ */
+
+int __journal_clean_checkpoint_list(journal_t *journal)
+{
+ transaction_t *transaction, *last_transaction, *next_transaction;
+ int ret = 0;
+ int released;
+
+ transaction = journal->j_checkpoint_transactions;
+ if (!transaction)
+ goto out;
+
+ last_transaction = transaction->t_cpprev;
+ next_transaction = transaction;
+ do {
+ transaction = next_transaction;
+ next_transaction = transaction->t_cpnext;
+ ret += journal_clean_one_cp_list(transaction->
+ t_checkpoint_list, &released);
+ /*
+ * This function only frees up some memory if possible so we
+ * dont have an obligation to finish processing. Bail out if
+ * preemption requested:
+ */
+ if (need_resched())
+ goto out;
+ if (released)
+ continue;
+ /*
+ * It is essential that we are as careful as in the case of
+ * t_checkpoint_list with removing the buffer from the list as
+ * we can possibly see not yet submitted buffers on io_list
+ */
+ ret += journal_clean_one_cp_list(transaction->
+ t_checkpoint_io_list, &released);
+ if (need_resched())
+ goto out;
+ } while (transaction != last_transaction);
+out:
+ return ret;
+}
+
+/*
+ * journal_remove_checkpoint: called after a buffer has been committed
+ * to disk (either by being write-back flushed to disk, or being
+ * committed to the log).
+ *
+ * We cannot safely clean a transaction out of the log until all of the
+ * buffer updates committed in that transaction have safely been stored
+ * elsewhere on disk. To achieve this, all of the buffers in a
+ * transaction need to be maintained on the transaction's checkpoint
+ * lists until they have been rewritten, at which point this function is
+ * called to remove the buffer from the existing transaction's
+ * checkpoint lists.
+ *
+ * The function returns 1 if it frees the transaction, 0 otherwise.
+ *
+ * This function is called with the journal locked.
+ * This function is called with j_list_lock held.
+ * This function is called with jbd_lock_bh_state(jh2bh(jh))
+ */
+
+int __journal_remove_checkpoint(struct journal_head *jh)
+{
+ transaction_t *transaction;
+ journal_t *journal;
+ int ret = 0;
+
+ JBUFFER_TRACE(jh, "entry");
+
+ if ((transaction = jh->b_cp_transaction) == NULL) {
+ JBUFFER_TRACE(jh, "not on transaction");
+ goto out;
+ }
+ journal = transaction->t_journal;
+
+ __buffer_unlink(jh);
+ jh->b_cp_transaction = NULL;
+
+ if (transaction->t_checkpoint_list != NULL ||
+ transaction->t_checkpoint_io_list != NULL)
+ goto out;
+ JBUFFER_TRACE(jh, "transaction has no more buffers");
+
+ /*
+ * There is one special case to worry about: if we have just pulled the
+ * buffer off a committing transaction's forget list, then even if the
+ * checkpoint list is empty, the transaction obviously cannot be
+ * dropped!
+ *
+ * The locking here around j_committing_transaction is a bit sleazy.
+ * See the comment at the end of journal_commit_transaction().
+ */
+ if (transaction == journal->j_committing_transaction) {
+ JBUFFER_TRACE(jh, "belongs to committing transaction");
+ goto out;
+ }
+
+ /* OK, that was the last buffer for the transaction: we can now
+ safely remove this transaction from the log */
+
+ __journal_drop_transaction(journal, transaction);
+
+ /* Just in case anybody was waiting for more transactions to be
+ checkpointed... */
+ wake_up(&journal->j_wait_logspace);
+ ret = 1;
+out:
+ JBUFFER_TRACE(jh, "exit");
+ return ret;
+}
+
+/*
+ * journal_insert_checkpoint: put a committed buffer onto a checkpoint
+ * list so that we know when it is safe to clean the transaction out of
+ * the log.
+ *
+ * Called with the journal locked.
+ * Called with j_list_lock held.
+ */
+void __journal_insert_checkpoint(struct journal_head *jh,
+ transaction_t *transaction)
+{
+ JBUFFER_TRACE(jh, "entry");
+ J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
+ J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
+
+ jh->b_cp_transaction = transaction;
+
+ if (!transaction->t_checkpoint_list) {
+ jh->b_cpnext = jh->b_cpprev = jh;
+ } else {
+ jh->b_cpnext = transaction->t_checkpoint_list;
+ jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
+ jh->b_cpprev->b_cpnext = jh;
+ jh->b_cpnext->b_cpprev = jh;
+ }
+ transaction->t_checkpoint_list = jh;
+}
+
+/*
+ * We've finished with this transaction structure: adios...
+ *
+ * The transaction must have no links except for the checkpoint by this
+ * point.
+ *
+ * Called with the journal locked.
+ * Called with j_list_lock held.
+ */
+
+void __journal_drop_transaction(journal_t *journal, transaction_t *transaction)
+{
+ assert_spin_locked(&journal->j_list_lock);
+ if (transaction->t_cpnext) {
+ transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
+ transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
+ if (journal->j_checkpoint_transactions == transaction)
+ journal->j_checkpoint_transactions =
+ transaction->t_cpnext;
+ if (journal->j_checkpoint_transactions == transaction)
+ journal->j_checkpoint_transactions = NULL;
+ }
+
+ J_ASSERT(transaction->t_state == T_FINISHED);
+ J_ASSERT(transaction->t_buffers == NULL);
+ J_ASSERT(transaction->t_sync_datalist == NULL);
+ J_ASSERT(transaction->t_forget == NULL);
+ J_ASSERT(transaction->t_iobuf_list == NULL);
+ J_ASSERT(transaction->t_shadow_list == NULL);
+ J_ASSERT(transaction->t_log_list == NULL);
+ J_ASSERT(transaction->t_checkpoint_list == NULL);
+ J_ASSERT(transaction->t_checkpoint_io_list == NULL);
+ J_ASSERT(transaction->t_updates == 0);
+ J_ASSERT(journal->j_committing_transaction != transaction);
+ J_ASSERT(journal->j_running_transaction != transaction);
+
+ jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
+ kfree(transaction);
+}
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
new file mode 100644
index 00000000000..10be51290a2
--- /dev/null
+++ b/fs/jbd2/commit.c
@@ -0,0 +1,911 @@
+/*
+ * linux/fs/jbd/commit.c
+ *
+ * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
+ *
+ * Copyright 1998 Red Hat corp --- All Rights Reserved
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * Journal commit routines for the generic filesystem journaling code;
+ * part of the ext2fs journaling system.
+ */
+
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/jbd.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/smp_lock.h>
+
+/*
+ * Default IO end handler for temporary BJ_IO buffer_heads.
+ */
+static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
+{
+ BUFFER_TRACE(bh, "");
+ if (uptodate)
+ set_buffer_uptodate(bh);
+ else
+ clear_buffer_uptodate(bh);
+ unlock_buffer(bh);
+}
+
+/*
+ * When an ext3-ordered file is truncated, it is possible that many pages are
+ * not sucessfully freed, because they are attached to a committing transaction.
+ * After the transaction commits, these pages are left on the LRU, with no
+ * ->mapping, and with attached buffers. These pages are trivially reclaimable
+ * by the VM, but their apparent absence upsets the VM accounting, and it makes
+ * the numbers in /proc/meminfo look odd.
+ *
+ * So here, we have a buffer which has just come off the forget list. Look to
+ * see if we can strip all buffers from the backing page.
+ *
+ * Called under lock_journal(), and possibly under journal_datalist_lock. The
+ * caller provided us with a ref against the buffer, and we drop that here.
+ */
+static void release_buffer_page(struct buffer_head *bh)
+{
+ struct page *page;
+
+ if (buffer_dirty(bh))
+ goto nope;
+ if (atomic_read(&bh->b_count) != 1)
+ goto nope;
+ page = bh->b_page;
+ if (!page)
+ goto nope;
+ if (page->mapping)
+ goto nope;
+
+ /* OK, it's a truncated page */
+ if (TestSetPageLocked(page))
+ goto nope;
+
+ page_cache_get(page);
+ __brelse(bh);
+ try_to_free_buffers(page);
+ unlock_page(page);
+ page_cache_release(page);
+ return;
+
+nope:
+ __brelse(bh);
+}
+
+/*
+ * Try to acquire jbd_lock_bh_state() against the buffer, when j_list_lock is
+ * held. For ranking reasons we must trylock. If we lose, schedule away and
+ * return 0. j_list_lock is dropped in this case.
+ */
+static int inverted_lock(journal_t *journal, struct buffer_head *bh)
+{
+ if (!jbd_trylock_bh_state(bh)) {
+ spin_unlock(&journal->j_list_lock);
+ schedule();
+ return 0;
+ }
+ return 1;
+}
+
+/* Done it all: now write the commit record. We should have
+ * cleaned up our previous buffers by now, so if we are in abort
+ * mode we can now just skip the rest of the journal write
+ * entirely.
+ *
+ * Returns 1 if the journal needs to be aborted or 0 on success
+ */
+static int journal_write_commit_record(journal_t *journal,
+ transaction_t *commit_transaction)
+{
+ struct journal_head *descriptor;
+ struct buffer_head *bh;
+ int i, ret;
+ int barrier_done = 0;
+
+ if (is_journal_aborted(journal))
+ return 0;
+
+ descriptor = journal_get_descriptor_buffer(journal);
+ if (!descriptor)
+ return 1;
+
+ bh = jh2bh(descriptor);
+
+ /* AKPM: buglet - add `i' to tmp! */
+ for (i = 0; i < bh->b_size; i += 512) {
+ journal_header_t *tmp = (journal_header_t*)bh->b_data;
+ tmp->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
+ tmp->h_blocktype = cpu_to_be32(JFS_COMMIT_BLOCK);
+ tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid);
+ }
+
+ JBUFFER_TRACE(descriptor, "write commit block");
+ set_buffer_dirty(bh);
+ if (journal->j_flags & JFS_BARRIER) {
+ set_buffer_ordered(bh);
+ barrier_done = 1;
+ }
+ ret = sync_dirty_buffer(bh);
+ /* is it possible for another commit to fail at roughly
+ * the same time as this one? If so, we don't want to
+ * trust the barrier flag in the super, but instead want
+ * to remember if we sent a barrier request
+ */
+ if (ret == -EOPNOTSUPP && barrier_done) {
+ char b[BDEVNAME_SIZE];
+
+ printk(KERN_WARNING
+ "JBD: barrier-based sync failed on %s - "
+ "disabling barriers\n",
+ bdevname(journal->j_dev, b));
+ spin_lock(&journal->j_state_lock);
+ journal->j_flags &= ~JFS_BARRIER;
+ spin_unlock(&journal->j_state_lock);
+
+ /* And try again, without the barrier */
+ clear_buffer_ordered(bh);
+ set_buffer_uptodate(bh);
+ set_buffer_dirty(bh);
+ ret = sync_dirty_buffer(bh);
+ }
+ put_bh(bh); /* One for getblk() */
+ journal_put_journal_head(descriptor);
+
+ return (ret == -EIO);
+}
+
+static void journal_do_submit_data(struct buffer_head **wbuf, int bufs)
+{
+ int i;
+
+ for (i = 0; i < bufs; i++) {
+ wbuf[i]->b_end_io = end_buffer_write_sync;
+ /* We use-up our safety reference in submit_bh() */
+ submit_bh(WRITE, wbuf[i]);
+ }
+}
+
+/*
+ * Submit all the data buffers to disk
+ */
+static void journal_submit_data_buffers(journal_t *journal,
+ transaction_t *commit_transaction)
+{
+ struct journal_head *jh;
+ struct buffer_head *bh;
+ int locked;
+ int bufs = 0;
+ struct buffer_head **wbuf = journal->j_wbuf;
+
+ /*
+ * Whenever we unlock the journal and sleep, things can get added
+ * onto ->t_sync_datalist, so we have to keep looping back to
+ * write_out_data until we *know* that the list is empty.
+ *
+ * Cleanup any flushed data buffers from the data list. Even in
+ * abort mode, we want to flush this out as soon as possible.
+ */
+write_out_data:
+ cond_resched();
+ spin_lock(&journal->j_list_lock);
+
+ while (commit_transaction->t_sync_datalist) {
+ jh = commit_transaction->t_sync_datalist;
+ bh = jh2bh(jh);
+ locked = 0;
+
+ /* Get reference just to make sure buffer does not disappear
+ * when we are forced to drop various locks */
+ get_bh(bh);
+ /* If the buffer is dirty, we need to submit IO and hence
+ * we need the buffer lock. We try to lock the buffer without
+ * blocking. If we fail, we need to drop j_list_lock and do
+ * blocking lock_buffer().
+ */
+ if (buffer_dirty(bh)) {
+ if (test_set_buffer_locked(bh)) {
+ BUFFER_TRACE(bh, "needs blocking lock");
+ spin_unlock(&journal->j_list_lock);
+ /* Write out all data to prevent deadlocks */
+ journal_do_submit_data(wbuf, bufs);
+ bufs = 0;
+ lock_buffer(bh);
+ spin_lock(&journal->j_list_lock);
+ }
+ locked = 1;
+ }
+ /* We have to get bh_state lock. Again out of order, sigh. */
+ if (!inverted_lock(journal, bh)) {
+ jbd_lock_bh_state(bh);
+ spin_lock(&journal->j_list_lock);
+ }
+ /* Someone already cleaned up the buffer? */
+ if (!buffer_jbd(bh)
+ || jh->b_transaction != commit_transaction
+ || jh->b_jlist != BJ_SyncData) {
+ jbd_unlock_bh_state(bh);
+ if (locked)
+ unlock_buffer(bh);
+ BUFFER_TRACE(bh, "already cleaned up");
+ put_bh(bh);
+ continue;
+ }
+ if (locked && test_clear_buffer_dirty(bh)) {
+ BUFFER_TRACE(bh, "needs writeout, adding to array");
+ wbuf[bufs++] = bh;
+ __journal_file_buffer(jh, commit_transaction,
+ BJ_Locked);
+ jbd_unlock_bh_state(bh);
+ if (bufs == journal->j_wbufsize) {
+ spin_unlock(&journal->j_list_lock);
+ journal_do_submit_data(wbuf, bufs);
+ bufs = 0;
+ goto write_out_data;
+ }
+ }
+ else {
+ BUFFER_TRACE(bh, "writeout complete: unfile");
+ __journal_unfile_buffer(jh);
+ jbd_unlock_bh_state(bh);
+ if (locked)
+ unlock_buffer(bh);
+ journal_remove_journal_head(bh);
+ /* Once for our safety reference, once for
+ * journal_remove_journal_head() */
+ put_bh(bh);
+ put_bh(bh);
+ }
+
+ if (lock_need_resched(&journal->j_list_lock)) {
+ spin_unlock(&journal->j_list_lock);
+ goto write_out_data;
+ }
+ }
+ spin_unlock(&journal->j_list_lock);
+ journal_do_submit_data(wbuf, bufs);
+}
+
+/*
+ * journal_commit_transaction
+ *
+ * The primary function for committing a transaction to the log. This
+ * function is called by the journal thread to begin a complete commit.
+ */
+void journal_commit_transaction(journal_t *journal)
+{
+ transaction_t *commit_transaction;
+ struct journal_head *jh, *new_jh, *descriptor;
+ struct buffer_head **wbuf = journal->j_wbuf;
+ int bufs;
+ int flags;
+ int err;
+ unsigned long blocknr;
+ char *tagp = NULL;
+ journal_header_t *header;
+ journal_block_tag_t *tag = NULL;
+ int space_left = 0;
+ int first_tag = 0;
+ int tag_flag;
+ int i;
+
+ /*
+ * First job: lock down the current transaction and wait for
+ * all outstanding updates to complete.
+ */
+
+#ifdef COMMIT_STATS
+ spin_lock(&journal->j_list_lock);
+ summarise_journal_usage(journal);
+ spin_unlock(&journal->j_list_lock);
+#endif
+
+ /* Do we need to erase the effects of a prior journal_flush? */
+ if (journal->j_flags & JFS_FLUSHED) {
+ jbd_debug(3, "super block updated\n");
+ journal_update_superblock(journal, 1);
+ } else {
+ jbd_debug(3, "superblock not updated\n");
+ }
+
+ J_ASSERT(journal->j_running_transaction != NULL);
+ J_ASSERT(journal->j_committing_transaction == NULL);
+
+ commit_transaction = journal->j_running_transaction;
+ J_ASSERT(commit_transaction->t_state == T_RUNNING);
+
+ jbd_debug(1, "JBD: starting commit of transaction %d\n",
+ commit_transaction->t_tid);
+
+ spin_lock(&journal->j_state_lock);
+ commit_transaction->t_state = T_LOCKED;
+
+ spin_lock(&commit_transaction->t_handle_lock);
+ while (commit_transaction->t_updates) {
+ DEFINE_WAIT(wait);
+
+ prepare_to_wait(&journal->j_wait_updates, &wait,
+ TASK_UNINTERRUPTIBLE);
+ if (commit_transaction->t_updates) {
+ spin_unlock(&commit_transaction->t_handle_lock);
+ spin_unlock(&journal->j_state_lock);
+ schedule();
+ spin_lock(&journal->j_state_lock);
+ spin_lock(&commit_transaction->t_handle_lock);
+ }
+ finish_wait(&journal->j_wait_updates, &wait);
+ }
+ spin_unlock(&commit_transaction->t_handle_lock);
+
+ J_ASSERT (commit_transaction->t_outstanding_credits <=
+ journal->j_max_transaction_buffers);
+
+ /*
+ * First thing we are allowed to do is to discard any remaining
+ * BJ_Reserved buffers. Note, it is _not_ permissible to assume
+ * that there are no such buffers: if a large filesystem
+ * operation like a truncate needs to split itself over multiple
+ * transactions, then it may try to do a journal_restart() while
+ * there are still BJ_Reserved buffers outstanding. These must
+ * be released cleanly from the current transaction.
+ *
+ * In this case, the filesystem must still reserve write access
+ * again before modifying the buffer in the new transaction, but
+ * we do not require it to remember exactly which old buffers it
+ * has reserved. This is consistent with the existing behaviour
+ * that multiple journal_get_write_access() calls to the same
+ * buffer are perfectly permissable.
+ */
+ while (commit_transaction->t_reserved_list) {
+ jh = commit_transaction->t_reserved_list;
+ JBUFFER_TRACE(jh, "reserved, unused: refile");
+ /*
+ * A journal_get_undo_access()+journal_release_buffer() may
+ * leave undo-committed data.
+ */
+ if (jh->b_committed_data) {
+ struct buffer_head *bh = jh2bh(jh);
+
+ jbd_lock_bh_state(bh);
+ jbd_slab_free(jh->b_committed_data, bh->b_size);
+ jh->b_committed_data = NULL;
+ jbd_unlock_bh_state(bh);
+ }
+ journal_refile_buffer(journal, jh);
+ }
+
+ /*
+ * Now try to drop any written-back buffers from the journal's
+ * checkpoint lists. We do this *before* commit because it potentially
+ * frees some memory
+ */
+ spin_lock(&journal->j_list_lock);
+ __journal_clean_checkpoint_list(journal);
+ spin_unlock(&journal->j_list_lock);
+
+ jbd_debug (3, "JBD: commit phase 1\n");
+
+ /*
+ * Switch to a new revoke table.
+ */
+ journal_switch_revoke_table(journal);
+
+ commit_transaction->t_state = T_FLUSH;
+ journal->j_committing_transaction = commit_transaction;
+ journal->j_running_transaction = NULL;
+ commit_transaction->t_log_start = journal->j_head;
+ wake_up(&journal->j_wait_transaction_locked);
+ spin_unlock(&journal->j_state_lock);
+
+ jbd_debug (3, "JBD: commit phase 2\n");
+
+ /*
+ * First, drop modified flag: all accesses to the buffers
+ * will be tracked for a new trasaction only -bzzz
+ */
+ spin_lock(&journal->j_list_lock);
+ if (commit_transaction->t_buffers) {
+ new_jh = jh = commit_transaction->t_buffers->b_tnext;
+ do {
+ J_ASSERT_JH(new_jh, new_jh->b_modified == 1 ||
+ new_jh->b_modified == 0);
+ new_jh->b_modified = 0;
+ new_jh = new_jh->b_tnext;
+ } while (new_jh != jh);
+ }
+ spin_unlock(&journal->j_list_lock);
+
+ /*
+ * Now start flushing things to disk, in the order they appear
+ * on the transaction lists. Data blocks go first.
+ */
+ err = 0;
+ journal_submit_data_buffers(journal, commit_transaction);
+
+ /*
+ * Wait for all previously submitted IO to complete.
+ */
+ spin_lock(&journal->j_list_lock);
+ while (commit_transaction->t_locked_list) {
+ struct buffer_head *bh;
+
+ jh = commit_transaction->t_locked_list->b_tprev;
+ bh = jh2bh(jh);
+ get_bh(bh);
+ if (buffer_locked(bh)) {
+ spin_unlock(&journal->j_list_lock);
+ wait_on_buffer(bh);
+ if (unlikely(!buffer_uptodate(bh)))
+ err = -EIO;
+ spin_lock(&journal->j_list_lock);
+ }
+ if (!inverted_lock(journal, bh)) {
+ put_bh(bh);
+ spin_lock(&journal->j_list_lock);
+ continue;
+ }
+ if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) {
+ __journal_unfile_buffer(jh);
+ jbd_unlock_bh_state(bh);
+ journal_remove_journal_head(bh);
+ put_bh(bh);
+ } else {
+ jbd_unlock_bh_state(bh);
+ }
+ put_bh(bh);
+ cond_resched_lock(&journal->j_list_lock);
+ }
+ spin_unlock(&journal->j_list_lock);
+
+ if (err)
+ __journal_abort_hard(journal);
+
+ journal_write_revoke_records(journal, commit_transaction);
+
+ jbd_debug(3, "JBD: commit phase 2\n");
+
+ /*
+ * If we found any dirty or locked buffers, then we should have
+ * looped back up to the write_out_data label. If there weren't
+ * any then journal_clean_data_list should have wiped the list
+ * clean by now, so check that it is in fact empty.
+ */
+ J_ASSERT (commit_transaction->t_sync_datalist == NULL);
+
+ jbd_debug (3, "JBD: commit phase 3\n");
+
+ /*
+ * Way to go: we have now written out all of the data for a
+ * transaction! Now comes the tricky part: we need to write out
+ * metadata. Loop over the transaction's entire buffer list:
+ */
+ commit_transaction->t_state = T_COMMIT;
+
+ descriptor = NULL;
+ bufs = 0;
+ while (commit_transaction->t_buffers) {
+
+ /* Find the next buffer to be journaled... */
+
+ jh = commit_transaction->t_buffers;
+
+ /* If we're in abort mode, we just un-journal the buffer and
+ release it for background writing. */
+
+ if (is_journal_aborted(journal)) {
+ JBUFFER_TRACE(jh, "journal is aborting: refile");
+ journal_refile_buffer(journal, jh);
+ /* If that was the last one, we need to clean up
+ * any descriptor buffers which may have been
+ * already allocated, even if we are now
+ * aborting. */
+ if (!commit_transaction->t_buffers)
+ goto start_journal_io;
+ continue;
+ }
+
+ /* Make sure we have a descriptor block in which to
+ record the metadata buffer. */
+
+ if (!descriptor) {
+ struct buffer_head *bh;
+
+ J_ASSERT (bufs == 0);
+
+ jbd_debug(4, "JBD: get descriptor\n");
+
+ descriptor = journal_get_descriptor_buffer(journal);
+ if (!descriptor) {
+ __journal_abort_hard(journal);
+ continue;
+ }
+
+ bh = jh2bh(descriptor);
+ jbd_debug(4, "JBD: got buffer %llu (%p)\n",
+ (unsigned long long)bh->b_blocknr, bh->b_data);
+ header = (journal_header_t *)&bh->b_data[0];
+ header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
+ header->h_blocktype = cpu_to_be32(JFS_DESCRIPTOR_BLOCK);
+ header->h_sequence = cpu_to_be32(commit_transaction->t_tid);
+
+ tagp = &bh->b_data[sizeof(journal_header_t)];
+ space_left = bh->b_size - sizeof(journal_header_t);
+ first_tag = 1;
+ set_buffer_jwrite(bh);
+ set_buffer_dirty(bh);
+ wbuf[bufs++] = bh;
+
+ /* Record it so that we can wait for IO
+ completion later */
+ BUFFER_TRACE(bh, "ph3: file as descriptor");
+ journal_file_buffer(descriptor, commit_transaction,
+ BJ_LogCtl);
+ }
+
+ /* Where is the buffer to be written? */
+
+ err = journal_next_log_block(journal, &blocknr);
+ /* If the block mapping failed, just abandon the buffer
+ and repeat this loop: we'll fall into the
+ refile-on-abort condition above. */
+ if (err) {
+ __journal_abort_hard(journal);
+ continue;
+ }
+
+ /*
+ * start_this_handle() uses t_outstanding_credits to determine
+ * the free space in the log, but this counter is changed
+ * by journal_next_log_block() also.
+ */
+ commit_transaction->t_outstanding_credits--;
+
+ /* Bump b_count to prevent truncate from stumbling over
+ the shadowed buffer! @@@ This can go if we ever get
+ rid of the BJ_IO/BJ_Shadow pairing of buffers. */
+ atomic_inc(&jh2bh(jh)->b_count);
+
+ /* Make a temporary IO buffer with which to write it out
+ (this will requeue both the metadata buffer and the
+ temporary IO buffer). new_bh goes on BJ_IO*/
+
+ set_bit(BH_JWrite, &jh2bh(jh)->b_state);
+ /*
+ * akpm: journal_write_metadata_buffer() sets
+ * new_bh->b_transaction to commit_transaction.
+ * We need to clean this up before we release new_bh
+ * (which is of type BJ_IO)
+ */
+ JBUFFER_TRACE(jh, "ph3: write metadata");
+ flags = journal_write_metadata_buffer(commit_transaction,
+ jh, &new_jh, blocknr);
+ set_bit(BH_JWrite, &jh2bh(new_jh)->b_state);
+ wbuf[bufs++] = jh2bh(new_jh);
+
+ /* Record the new block's tag in the current descriptor
+ buffer */
+
+ tag_flag = 0;
+ if (flags & 1)
+ tag_flag |= JFS_FLAG_ESCAPE;
+ if (!first_tag)
+ tag_flag |= JFS_FLAG_SAME_UUID;
+
+ tag = (journal_block_tag_t *) tagp;
+ tag->t_blocknr = cpu_to_be32(jh2bh(jh)->b_blocknr);
+ tag->t_flags = cpu_to_be32(tag_flag);
+ tagp += sizeof(journal_block_tag_t);
+ space_left -= sizeof(journal_block_tag_t);
+
+ if (first_tag) {
+ memcpy (tagp, journal->j_uuid, 16);
+ tagp += 16;
+ space_left -= 16;
+ first_tag = 0;
+ }
+
+ /* If there's no more to do, or if the descriptor is full,
+ let the IO rip! */
+
+ if (bufs == journal->j_wbufsize ||
+ commit_transaction->t_buffers == NULL ||
+ space_left < sizeof(journal_block_tag_t) + 16) {
+
+ jbd_debug(4, "JBD: Submit %d IOs\n", bufs);
+
+ /* Write an end-of-descriptor marker before
+ submitting the IOs. "tag" still points to
+ the last tag we set up. */
+
+ tag->t_flags |= cpu_to_be32(JFS_FLAG_LAST_TAG);
+
+start_journal_io:
+ for (i = 0; i < bufs; i++) {
+ struct buffer_head *bh = wbuf[i];
+ lock_buffer(bh);
+ clear_buffer_dirty(bh);
+ set_buffer_uptodate(bh);
+ bh->b_end_io = journal_end_buffer_io_sync;
+ submit_bh(WRITE, bh);
+ }
+ cond_resched();
+
+ /* Force a new descriptor to be generated next
+ time round the loop. */
+ descriptor = NULL;
+ bufs = 0;
+ }
+ }
+
+ /* Lo and behold: we have just managed to send a transaction to
+ the log. Before we can commit it, wait for the IO so far to
+ complete. Control buffers being written are on the
+ transaction's t_log_list queue, and metadata buffers are on
+ the t_iobuf_list queue.
+
+ Wait for the buffers in reverse order. That way we are
+ less likely to be woken up until all IOs have completed, and
+ so we incur less scheduling load.
+ */
+
+ jbd_debug(3, "JBD: commit phase 4\n");
+
+ /*
+ * akpm: these are BJ_IO, and j_list_lock is not needed.
+ * See __journal_try_to_free_buffer.
+ */
+wait_for_iobuf:
+ while (commit_transaction->t_iobuf_list != NULL) {
+ struct buffer_head *bh;
+
+ jh = commit_transaction->t_iobuf_list->b_tprev;
+ bh = jh2bh(jh);
+ if (buffer_locked(bh)) {
+ wait_on_buffer(bh);
+ goto wait_for_iobuf;
+ }
+ if (cond_resched())
+ goto wait_for_iobuf;
+
+ if (unlikely(!buffer_uptodate(bh)))
+ err = -EIO;
+
+ clear_buffer_jwrite(bh);
+
+ JBUFFER_TRACE(jh, "ph4: unfile after journal write");
+ journal_unfile_buffer(journal, jh);
+
+ /*
+ * ->t_iobuf_list should contain only dummy buffer_heads
+ * which were created by journal_write_metadata_buffer().
+ */
+ BUFFER_TRACE(bh, "dumping temporary bh");
+ journal_put_journal_head(jh);
+ __brelse(bh);
+ J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
+ free_buffer_head(bh);
+
+ /* We also have to unlock and free the corresponding
+ shadowed buffer */
+ jh = commit_transaction->t_shadow_list->b_tprev;
+ bh = jh2bh(jh);
+ clear_bit(BH_JWrite, &bh->b_state);
+ J_ASSERT_BH(bh, buffer_jbddirty(bh));
+
+ /* The metadata is now released for reuse, but we need
+ to remember it against this transaction so that when
+ we finally commit, we can do any checkpointing
+ required. */
+ JBUFFER_TRACE(jh, "file as BJ_Forget");
+ journal_file_buffer(jh, commit_transaction, BJ_Forget);
+ /* Wake up any transactions which were waiting for this
+ IO to complete */
+ wake_up_bit(&bh->b_state, BH_Unshadow);
+ JBUFFER_TRACE(jh, "brelse shadowed buffer");
+ __brelse(bh);
+ }
+
+ J_ASSERT (commit_transaction->t_shadow_list == NULL);
+
+ jbd_debug(3, "JBD: commit phase 5\n");
+
+ /* Here we wait for the revoke record and descriptor record buffers */
+ wait_for_ctlbuf:
+ while (commit_transaction->t_log_list != NULL) {
+ struct buffer_head *bh;
+
+ jh = commit_transaction->t_log_list->b_tprev;
+ bh = jh2bh(jh);
+ if (buffer_locked(bh)) {
+ wait_on_buffer(bh);
+ goto wait_for_ctlbuf;
+ }
+ if (cond_resched())
+ goto wait_for_ctlbuf;
+
+ if (unlikely(!buffer_uptodate(bh)))
+ err = -EIO;
+
+ BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
+ clear_buffer_jwrite(bh);
+ journal_unfile_buffer(journal, jh);
+ journal_put_journal_head(jh);
+ __brelse(bh); /* One for getblk */
+ /* AKPM: bforget here */
+ }
+
+ jbd_debug(3, "JBD: commit phase 6\n");
+
+ if (journal_write_commit_record(journal, commit_transaction))
+ err = -EIO;
+
+ if (err)
+ __journal_abort_hard(journal);
+
+ /* End of a transaction! Finally, we can do checkpoint
+ processing: any buffers committed as a result of this
+ transaction can be removed from any checkpoint list it was on
+ before. */
+
+ jbd_debug(3, "JBD: commit phase 7\n");
+
+ J_ASSERT(commit_transaction->t_sync_datalist == NULL);
+ J_ASSERT(commit_transaction->t_buffers == NULL);
+ J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
+ J_ASSERT(commit_transaction->t_iobuf_list == NULL);
+ J_ASSERT(commit_transaction->t_shadow_list == NULL);
+ J_ASSERT(commit_transaction->t_log_list == NULL);
+
+restart_loop:
+ /*
+ * As there are other places (journal_unmap_buffer()) adding buffers
+ * to this list we have to be careful and hold the j_list_lock.
+ */
+ spin_lock(&journal->j_list_lock);
+ while (commit_transaction->t_forget) {
+ transaction_t *cp_transaction;
+ struct buffer_head *bh;
+
+ jh = commit_transaction->t_forget;
+ spin_unlock(&journal->j_list_lock);
+ bh = jh2bh(jh);
+ jbd_lock_bh_state(bh);
+ J_ASSERT_JH(jh, jh->b_transaction == commit_transaction ||
+ jh->b_transaction == journal->j_running_transaction);
+
+ /*
+ * If there is undo-protected committed data against
+ * this buffer, then we can remove it now. If it is a
+ * buffer needing such protection, the old frozen_data
+ * field now points to a committed version of the
+ * buffer, so rotate that field to the new committed
+ * data.
+ *
+ * Otherwise, we can just throw away the frozen data now.
+ */
+ if (jh->b_committed_data) {
+ jbd_slab_free(jh->b_committed_data, bh->b_size);
+ jh->b_committed_data = NULL;
+ if (jh->b_frozen_data) {
+ jh->b_committed_data = jh->b_frozen_data;
+ jh->b_frozen_data = NULL;
+ }
+ } else if (jh->b_frozen_data) {
+ jbd_slab_free(jh->b_frozen_data, bh->b_size);
+ jh->b_frozen_data = NULL;
+ }
+
+ spin_lock(&journal->j_list_lock);
+ cp_transaction = jh->b_cp_transaction;
+ if (cp_transaction) {
+ JBUFFER_TRACE(jh, "remove from old cp transaction");
+ __journal_remove_checkpoint(jh);
+ }
+
+ /* Only re-checkpoint the buffer_head if it is marked
+ * dirty. If the buffer was added to the BJ_Forget list
+ * by journal_forget, it may no longer be dirty and
+ * there's no point in keeping a checkpoint record for
+ * it. */
+
+ /* A buffer which has been freed while still being
+ * journaled by a previous transaction may end up still
+ * being dirty here, but we want to avoid writing back
+ * that buffer in the future now that the last use has
+ * been committed. That's not only a performance gain,
+ * it also stops aliasing problems if the buffer is left
+ * behind for writeback and gets reallocated for another
+ * use in a different page. */
+ if (buffer_freed(bh)) {
+ clear_buffer_freed(bh);
+ clear_buffer_jbddirty(bh);
+ }
+
+ if (buffer_jbddirty(bh)) {
+ JBUFFER_TRACE(jh, "add to new checkpointing trans");
+ __journal_insert_checkpoint(jh, commit_transaction);
+ JBUFFER_TRACE(jh, "refile for checkpoint writeback");
+ __journal_refile_buffer(jh);
+ jbd_unlock_bh_state(bh);
+ } else {
+ J_ASSERT_BH(bh, !buffer_dirty(bh));
+ /* The buffer on BJ_Forget list and not jbddirty means
+ * it has been freed by this transaction and hence it
+ * could not have been reallocated until this
+ * transaction has committed. *BUT* it could be
+ * reallocated once we have written all the data to
+ * disk and before we process the buffer on BJ_Forget
+ * list. */
+ JBUFFER_TRACE(jh, "refile or unfile freed buffer");
+ __journal_refile_buffer(jh);
+ if (!jh->b_transaction) {
+ jbd_unlock_bh_state(bh);
+ /* needs a brelse */
+ journal_remove_journal_head(bh);
+ release_buffer_page(bh);
+ } else
+ jbd_unlock_bh_state(bh);
+ }
+ cond_resched_lock(&journal->j_list_lock);
+ }
+ spin_unlock(&journal->j_list_lock);
+ /*
+ * This is a bit sleazy. We borrow j_list_lock to protect
+ * journal->j_committing_transaction in __journal_remove_checkpoint.
+ * Really, __journal_remove_checkpoint should be using j_state_lock but
+ * it's a bit hassle to hold that across __journal_remove_checkpoint
+ */
+ spin_lock(&journal->j_state_lock);
+ spin_lock(&journal->j_list_lock);
+ /*
+ * Now recheck if some buffers did not get attached to the transaction
+ * while the lock was dropped...
+ */
+ if (commit_transaction->t_forget) {
+ spin_unlock(&journal->j_list_lock);
+ spin_unlock(&journal->j_state_lock);
+ goto restart_loop;
+ }
+
+ /* Done with this transaction! */
+
+ jbd_debug(3, "JBD: commit phase 8\n");
+
+ J_ASSERT(commit_transaction->t_state == T_COMMIT);
+
+ commit_transaction->t_state = T_FINISHED;
+ J_ASSERT(commit_transaction == journal->j_committing_transaction);
+ journal->j_commit_sequence = commit_transaction->t_tid;
+ journal->j_committing_transaction = NULL;
+ spin_unlock(&journal->j_state_lock);
+
+ if (commit_transaction->t_checkpoint_list == NULL) {
+ __journal_drop_transaction(journal, commit_transaction);
+ } else {
+ if (journal->j_checkpoint_transactions == NULL) {
+ journal->j_checkpoint_transactions = commit_transaction;
+ commit_transaction->t_cpnext = commit_transaction;
+ commit_transaction->t_cpprev = commit_transaction;
+ } else {
+ commit_transaction->t_cpnext =
+ journal->j_checkpoint_transactions;
+ commit_transaction->t_cpprev =
+ commit_transaction->t_cpnext->t_cpprev;
+ commit_transaction->t_cpnext->t_cpprev =
+ commit_transaction;
+ commit_transaction->t_cpprev->t_cpnext =
+ commit_transaction;
+ }
+ }
+ spin_unlock(&journal->j_list_lock);
+
+ jbd_debug(1, "JBD: commit %d complete, head %d\n",
+ journal->j_commit_sequence, journal->j_tail_sequence);
+
+ wake_up(&journal->j_wait_done_commit);
+}
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
new file mode 100644
index 00000000000..c518dd8fe60
--- /dev/null
+++ b/fs/jbd2/journal.c
@@ -0,0 +1,2072 @@
+/*
+ * linux/fs/jbd/journal.c
+ *
+ * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
+ *
+ * Copyright 1998 Red Hat corp --- All Rights Reserved
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * Generic filesystem journal-writing code; part of the ext2fs
+ * journaling system.
+ *
+ * This file manages journals: areas of disk reserved for logging
+ * transactional updates. This includes the kernel journaling thread
+ * which is responsible for scheduling updates to the log.
+ *
+ * We do not actually manage the physical storage of the journal in this
+ * file: that is left to a per-journal policy function, which allows us
+ * to store the journal within a filesystem-specified area for ext2
+ * journaling (ext2 can use a reserved inode for storing the log).
+ */
+
+#include <linux/module.h>
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/jbd.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/smp_lock.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/suspend.h>
+#include <linux/pagemap.h>
+#include <linux/kthread.h>
+#include <linux/poison.h>
+#include <linux/proc_fs.h>
+
+#include <asm/uaccess.h>
+#include <asm/page.h>
+
+EXPORT_SYMBOL(journal_start);
+EXPORT_SYMBOL(journal_restart);
+EXPORT_SYMBOL(journal_extend);
+EXPORT_SYMBOL(journal_stop);
+EXPORT_SYMBOL(journal_lock_updates);
+EXPORT_SYMBOL(journal_unlock_updates);
+EXPORT_SYMBOL(journal_get_write_access);
+EXPORT_SYMBOL(journal_get_create_access);
+EXPORT_SYMBOL(journal_get_undo_access);
+EXPORT_SYMBOL(journal_dirty_data);
+EXPORT_SYMBOL(journal_dirty_metadata);
+EXPORT_SYMBOL(journal_release_buffer);
+EXPORT_SYMBOL(journal_forget);
+#if 0
+EXPORT_SYMBOL(journal_sync_buffer);
+#endif
+EXPORT_SYMBOL(journal_flush);
+EXPORT_SYMBOL(journal_revoke);
+
+EXPORT_SYMBOL(journal_init_dev);
+EXPORT_SYMBOL(journal_init_inode);
+EXPORT_SYMBOL(journal_update_format);
+EXPORT_SYMBOL(journal_check_used_features);
+EXPORT_SYMBOL(journal_check_available_features);
+EXPORT_SYMBOL(journal_set_features);
+EXPORT_SYMBOL(journal_create);
+EXPORT_SYMBOL(journal_load);
+EXPORT_SYMBOL(journal_destroy);
+EXPORT_SYMBOL(journal_update_superblock);
+EXPORT_SYMBOL(journal_abort);
+EXPORT_SYMBOL(journal_errno);
+EXPORT_SYMBOL(journal_ack_err);
+EXPORT_SYMBOL(journal_clear_err);
+EXPORT_SYMBOL(log_wait_commit);
+EXPORT_SYMBOL(journal_start_commit);
+EXPORT_SYMBOL(journal_force_commit_nested);
+EXPORT_SYMBOL(journal_wipe);
+EXPORT_SYMBOL(journal_blocks_per_page);
+EXPORT_SYMBOL(journal_invalidatepage);
+EXPORT_SYMBOL(journal_try_to_free_buffers);
+EXPORT_SYMBOL(journal_force_commit);
+
+static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
+static void __journal_abort_soft (journal_t *journal, int errno);
+static int journal_create_jbd_slab(size_t slab_size);
+
+/*
+ * Helper function used to manage commit timeouts
+ */
+
+static void commit_timeout(unsigned long __data)
+{
+ struct task_struct * p = (struct task_struct *) __data;
+
+ wake_up_process(p);
+}
+
+/*
+ * kjournald: The main thread function used to manage a logging device
+ * journal.
+ *
+ * This kernel thread is responsible for two things:
+ *
+ * 1) COMMIT: Every so often we need to commit the current state of the
+ * filesystem to disk. The journal thread is responsible for writing
+ * all of the metadata buffers to disk.
+ *
+ * 2) CHECKPOINT: We cannot reuse a used section of the log file until all
+ * of the data in that part of the log has been rewritten elsewhere on
+ * the disk. Flushing these old buffers to reclaim space in the log is
+ * known as checkpointing, and this thread is responsible for that job.
+ */
+
+static int kjournald(void *arg)
+{
+ journal_t *journal = arg;
+ transaction_t *transaction;
+
+ /*
+ * Set up an interval timer which can be used to trigger a commit wakeup
+ * after the commit interval expires
+ */
+ setup_timer(&journal->j_commit_timer, commit_timeout,
+ (unsigned long)current);
+
+ /* Record that the journal thread is running */
+ journal->j_task = current;
+ wake_up(&journal->j_wait_done_commit);
+
+ printk(KERN_INFO "kjournald starting. Commit interval %ld seconds\n",
+ journal->j_commit_interval / HZ);
+
+ /*
+ * And now, wait forever for commit wakeup events.
+ */
+ spin_lock(&journal->j_state_lock);
+
+loop:
+ if (journal->j_flags & JFS_UNMOUNT)
+ goto end_loop;
+
+ jbd_debug(1, "commit_sequence=%d, commit_request=%d\n",
+ journal->j_commit_sequence, journal->j_commit_request);
+
+ if (journal->j_commit_sequence != journal->j_commit_request) {
+ jbd_debug(1, "OK, requests differ\n");
+ spin_unlock(&journal->j_state_lock);
+ del_timer_sync(&journal->j_commit_timer);
+ journal_commit_transaction(journal);
+ spin_lock(&journal->j_state_lock);
+ goto loop;
+ }
+
+ wake_up(&journal->j_wait_done_commit);
+ if (freezing(current)) {
+ /*
+ * The simpler the better. Flushing journal isn't a
+ * good idea, because that depends on threads that may
+ * be already stopped.
+ */
+ jbd_debug(1, "Now suspending kjournald\n");
+ spin_unlock(&journal->j_state_lock);
+ refrigerator();
+ spin_lock(&journal->j_state_lock);
+ } else {
+ /*
+ * We assume on resume that commits are already there,
+ * so we don't sleep
+ */
+ DEFINE_WAIT(wait);
+ int should_sleep = 1;
+
+ prepare_to_wait(&journal->j_wait_commit, &wait,
+ TASK_INTERRUPTIBLE);
+ if (journal->j_commit_sequence != journal->j_commit_request)
+ should_sleep = 0;
+ transaction = journal->j_running_transaction;
+ if (transaction && time_after_eq(jiffies,
+ transaction->t_expires))
+ should_sleep = 0;
+ if (journal->j_flags & JFS_UNMOUNT)
+ should_sleep = 0;
+ if (should_sleep) {
+ spin_unlock(&journal->j_state_lock);
+ schedule();
+ spin_lock(&journal->j_state_lock);
+ }
+ finish_wait(&journal->j_wait_commit, &wait);
+ }
+
+ jbd_debug(1, "kjournald wakes\n");
+
+ /*
+ * Were we woken up by a commit wakeup event?
+ */
+ transaction = journal->j_running_transaction;
+ if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
+ journal->j_commit_request = transaction->t_tid;
+ jbd_debug(1, "woke because of timeout\n");
+ }
+ goto loop;
+
+end_loop:
+ spin_unlock(&journal->j_state_lock);
+ del_timer_sync(&journal->j_commit_timer);
+ journal->j_task = NULL;
+ wake_up(&journal->j_wait_done_commit);
+ jbd_debug(1, "Journal thread exiting.\n");
+ return 0;
+}
+
+static void journal_start_thread(journal_t *journal)
+{
+ kthread_run(kjournald, journal, "kjournald");
+ wait_event(journal->j_wait_done_commit, journal->j_task != 0);
+}
+
+static void journal_kill_thread(journal_t *journal)
+{
+ spin_lock(&journal->j_state_lock);
+ journal->j_flags |= JFS_UNMOUNT;
+
+ while (journal->j_task) {
+ wake_up(&journal->j_wait_commit);
+ spin_unlock(&journal->j_state_lock);
+ wait_event(journal->j_wait_done_commit, journal->j_task == 0);
+ spin_lock(&journal->j_state_lock);
+ }
+ spin_unlock(&journal->j_state_lock);
+}
+
+/*
+ * journal_write_metadata_buffer: write a metadata buffer to the journal.
+ *
+ * Writes a metadata buffer to a given disk block. The actual IO is not
+ * performed but a new buffer_head is constructed which labels the data
+ * to be written with the correct destination disk block.
+ *
+ * Any magic-number escaping which needs to be done will cause a
+ * copy-out here. If the buffer happens to start with the
+ * JFS_MAGIC_NUMBER, then we can't write it to the log directly: the
+ * magic number is only written to the log for descripter blocks. In
+ * this case, we copy the data and replace the first word with 0, and we
+ * return a result code which indicates that this buffer needs to be
+ * marked as an escaped buffer in the corresponding log descriptor
+ * block. The missing word can then be restored when the block is read
+ * during recovery.
+ *
+ * If the source buffer has already been modified by a new transaction
+ * since we took the last commit snapshot, we use the frozen copy of
+ * that data for IO. If we end up using the existing buffer_head's data
+ * for the write, then we *have* to lock the buffer to prevent anyone
+ * else from using and possibly modifying it while the IO is in
+ * progress.
+ *
+ * The function returns a pointer to the buffer_heads to be used for IO.
+ *
+ * We assume that the journal has already been locked in this function.
+ *
+ * Return value:
+ * <0: Error
+ * >=0: Finished OK
+ *
+ * On success:
+ * Bit 0 set == escape performed on the data
+ * Bit 1 set == buffer copy-out performed (kfree the data after IO)
+ */
+
+int journal_write_metadata_buffer(transaction_t *transaction,
+ struct journal_head *jh_in,
+ struct journal_head **jh_out,
+ unsigned long blocknr)
+{
+ int need_copy_out = 0;
+ int done_copy_out = 0;
+ int do_escape = 0;
+ char *mapped_data;
+ struct buffer_head *new_bh;
+ struct journal_head *new_jh;
+ struct page *new_page;
+ unsigned int new_offset;
+ struct buffer_head *bh_in = jh2bh(jh_in);
+
+ /*
+ * The buffer really shouldn't be locked: only the current committing
+ * transaction is allowed to write it, so nobody else is allowed
+ * to do any IO.
+ *
+ * akpm: except if we're journalling data, and write() output is
+ * also part of a shared mapping, and another thread has
+ * decided to launch a writepage() against this buffer.
+ */
+ J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
+
+ new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
+
+ /*
+ * If a new transaction has already done a buffer copy-out, then
+ * we use that version of the data for the commit.
+ */
+ jbd_lock_bh_state(bh_in);
+repeat:
+ if (jh_in->b_frozen_data) {
+ done_copy_out = 1;
+ new_page = virt_to_page(jh_in->b_frozen_data);
+ new_offset = offset_in_page(jh_in->b_frozen_data);
+ } else {
+ new_page = jh2bh(jh_in)->b_page;
+ new_offset = offset_in_page(jh2bh(jh_in)->b_data);
+ }
+
+ mapped_data = kmap_atomic(new_page, KM_USER0);
+ /*
+ * Check for escaping
+ */
+ if (*((__be32 *)(mapped_data + new_offset)) ==
+ cpu_to_be32(JFS_MAGIC_NUMBER)) {
+ need_copy_out = 1;
+ do_escape = 1;
+ }
+ kunmap_atomic(mapped_data, KM_USER0);
+
+ /*
+ * Do we need to do a data copy?
+ */
+ if (need_copy_out && !done_copy_out) {
+ char *tmp;
+
+ jbd_unlock_bh_state(bh_in);
+ tmp = jbd_slab_alloc(bh_in->b_size, GFP_NOFS);
+ jbd_lock_bh_state(bh_in);
+ if (jh_in->b_frozen_data) {
+ jbd_slab_free(tmp, bh_in->b_size);
+ goto repeat;
+ }
+
+ jh_in->b_frozen_data = tmp;
+ mapped_data = kmap_atomic(new_page, KM_USER0);
+ memcpy(tmp, mapped_data + new_offset, jh2bh(jh_in)->b_size);
+ kunmap_atomic(mapped_data, KM_USER0);
+
+ new_page = virt_to_page(tmp);
+ new_offset = offset_in_page(tmp);
+ done_copy_out = 1;
+ }
+
+ /*
+ * Did we need to do an escaping? Now we've done all the
+ * copying, we can finally do so.
+ */
+ if (do_escape) {
+ mapped_data = kmap_atomic(new_page, KM_USER0);
+ *((unsigned int *)(mapped_data + new_offset)) = 0;
+ kunmap_atomic(mapped_data, KM_USER0);
+ }
+
+ /* keep subsequent assertions sane */
+ new_bh->b_state = 0;
+ init_buffer(new_bh, NULL, NULL);
+ atomic_set(&new_bh->b_count, 1);
+ jbd_unlock_bh_state(bh_in);
+
+ new_jh = journal_add_journal_head(new_bh); /* This sleeps */
+
+ set_bh_page(new_bh, new_page, new_offset);
+ new_jh->b_transaction = NULL;
+ new_bh->b_size = jh2bh(jh_in)->b_size;
+ new_bh->b_bdev = transaction->t_journal->j_dev;
+ new_bh->b_blocknr = blocknr;
+ set_buffer_mapped(new_bh);
+ set_buffer_dirty(new_bh);
+
+ *jh_out = new_jh;
+
+ /*
+ * The to-be-written buffer needs to get moved to the io queue,
+ * and the original buffer whose contents we are shadowing or
+ * copying is moved to the transaction's shadow queue.
+ */
+ JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
+ journal_file_buffer(jh_in, transaction, BJ_Shadow);
+ JBUFFER_TRACE(new_jh, "file as BJ_IO");
+ journal_file_buffer(new_jh, transaction, BJ_IO);
+
+ return do_escape | (done_copy_out << 1);
+}
+
+/*
+ * Allocation code for the journal file. Manage the space left in the
+ * journal, so that we can begin checkpointing when appropriate.
+ */
+
+/*
+ * __log_space_left: Return the number of free blocks left in the journal.
+ *
+ * Called with the journal already locked.
+ *
+ * Called under j_state_lock
+ */
+
+int __log_space_left(journal_t *journal)
+{
+ int left = journal->j_free;
+
+ assert_spin_locked(&journal->j_state_lock);
+
+ /*
+ * Be pessimistic here about the number of those free blocks which
+ * might be required for log descriptor control blocks.
+ */
+
+#define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */
+
+ left -= MIN_LOG_RESERVED_BLOCKS;
+
+ if (left <= 0)
+ return 0;
+ left -= (left >> 3);
+ return left;
+}
+
+/*
+ * Called under j_state_lock. Returns true if a transaction was started.
+ */
+int __log_start_commit(journal_t *journal, tid_t target)
+{
+ /*
+ * Are we already doing a recent enough commit?
+ */
+ if (!tid_geq(journal->j_commit_request, target)) {
+ /*
+ * We want a new commit: OK, mark the request and wakup the
+ * commit thread. We do _not_ do the commit ourselves.
+ */
+
+ journal->j_commit_request = target;
+ jbd_debug(1, "JBD: requesting commit %d/%d\n",
+ journal->j_commit_request,
+ journal->j_commit_sequence);
+ wake_up(&journal->j_wait_commit);
+ return 1;
+ }
+ return 0;
+}
+
+int log_start_commit(journal_t *journal, tid_t tid)
+{
+ int ret;
+
+ spin_lock(&journal->j_state_lock);
+ ret = __log_start_commit(journal, tid);
+ spin_unlock(&journal->j_state_lock);
+ return ret;
+}
+
+/*
+ * Force and wait upon a commit if the calling process is not within
+ * transaction. This is used for forcing out undo-protected data which contains
+ * bitmaps, when the fs is running out of space.
+ *
+ * We can only force the running transaction if we don't have an active handle;
+ * otherwise, we will deadlock.
+ *
+ * Returns true if a transaction was started.
+ */
+int journal_force_commit_nested(journal_t *journal)
+{
+ transaction_t *transaction = NULL;
+ tid_t tid;
+
+ spin_lock(&journal->j_state_lock);
+ if (journal->j_running_transaction && !current->journal_info) {
+ transaction = journal->j_running_transaction;
+ __log_start_commit(journal, transaction->t_tid);
+ } else if (journal->j_committing_transaction)
+ transaction = journal->j_committing_transaction;
+
+ if (!transaction) {
+ spin_unlock(&journal->j_state_lock);
+ return 0; /* Nothing to retry */
+ }
+
+ tid = transaction->t_tid;
+ spin_unlock(&journal->j_state_lock);
+ log_wait_commit(journal, tid);
+ return 1;
+}
+
+/*
+ * Start a commit of the current running transaction (if any). Returns true
+ * if a transaction was started, and fills its tid in at *ptid
+ */
+int journal_start_commit(journal_t *journal, tid_t *ptid)
+{
+ int ret = 0;
+
+ spin_lock(&journal->j_state_lock);
+ if (journal->j_running_transaction) {
+ tid_t tid = journal->j_running_transaction->t_tid;
+
+ ret = __log_start_commit(journal, tid);
+ if (ret && ptid)
+ *ptid = tid;
+ } else if (journal->j_committing_transaction && ptid) {
+ /*
+ * If ext3_write_super() recently started a commit, then we
+ * have to wait for completion of that transaction
+ */
+ *ptid = journal->j_committing_transaction->t_tid;
+ ret = 1;
+ }
+ spin_unlock(&journal->j_state_lock);
+ return ret;
+}
+
+/*
+ * Wait for a specified commit to complete.
+ * The caller may not hold the journal lock.
+ */
+int log_wait_commit(journal_t *journal, tid_t tid)
+{
+ int err = 0;
+
+#ifdef CONFIG_JBD_DEBUG
+ spin_lock(&journal->j_state_lock);
+ if (!tid_geq(journal->j_commit_request, tid)) {
+ printk(KERN_EMERG
+ "%s: error: j_commit_request=%d, tid=%d\n",
+ __FUNCTION__, journal->j_commit_request, tid);
+ }
+ spin_unlock(&journal->j_state_lock);
+#endif
+ spin_lock(&journal->j_state_lock);
+ while (tid_gt(tid, journal->j_commit_sequence)) {
+ jbd_debug(1, "JBD: want %d, j_commit_sequence=%d\n",
+ tid, journal->j_commit_sequence);
+ wake_up(&journal->j_wait_commit);
+ spin_unlock(&journal->j_state_lock);
+ wait_event(journal->j_wait_done_commit,
+ !tid_gt(tid, journal->j_commit_sequence));
+ spin_lock(&journal->j_state_lock);
+ }
+ spin_unlock(&journal->j_state_lock);
+
+ if (unlikely(is_journal_aborted(journal))) {
+ printk(KERN_EMERG "journal commit I/O error\n");
+ err = -EIO;
+ }
+ return err;
+}
+
+/*
+ * Log buffer allocation routines:
+ */
+
+int journal_next_log_block(journal_t *journal, unsigned long *retp)
+{
+ unsigned long blocknr;
+
+ spin_lock(&journal->j_state_lock);
+ J_ASSERT(journal->j_free > 1);
+
+ blocknr = journal->j_head;
+ journal->j_head++;
+ journal->j_free--;
+ if (journal->j_head == journal->j_last)
+ journal->j_head = journal->j_first;
+ spin_unlock(&journal->j_state_lock);
+ return journal_bmap(journal, blocknr, retp);
+}
+
+/*
+ * Conversion of logical to physical block numbers for the journal
+ *
+ * On external journals the journal blocks are identity-mapped, so
+ * this is a no-op. If needed, we can use j_blk_offset - everything is
+ * ready.
+ */
+int journal_bmap(journal_t *journal, unsigned long blocknr,
+ unsigned long *retp)
+{
+ int err = 0;
+ unsigned long ret;
+
+ if (journal->j_inode) {
+ ret = bmap(journal->j_inode, blocknr);
+ if (ret)
+ *retp = ret;
+ else {
+ char b[BDEVNAME_SIZE];
+
+ printk(KERN_ALERT "%s: journal block not found "
+ "at offset %lu on %s\n",
+ __FUNCTION__,
+ blocknr,
+ bdevname(journal->j_dev, b));
+ err = -EIO;
+ __journal_abort_soft(journal, err);
+ }
+ } else {
+ *retp = blocknr; /* +journal->j_blk_offset */
+ }
+ return err;
+}
+
+/*
+ * We play buffer_head aliasing tricks to write data/metadata blocks to
+ * the journal without copying their contents, but for journal
+ * descriptor blocks we do need to generate bona fide buffers.
+ *
+ * After the caller of journal_get_descriptor_buffer() has finished modifying
+ * the buffer's contents they really should run flush_dcache_page(bh->b_page).
+ * But we don't bother doing that, so there will be coherency problems with
+ * mmaps of blockdevs which hold live JBD-controlled filesystems.
+ */
+struct journal_head *journal_get_descriptor_buffer(journal_t *journal)
+{
+ struct buffer_head *bh;
+ unsigned long blocknr;
+ int err;
+
+ err = journal_next_log_block(journal, &blocknr);
+
+ if (err)
+ return NULL;
+
+ bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
+ lock_buffer(bh);
+ memset(bh->b_data, 0, journal->j_blocksize);
+ set_buffer_uptodate(bh);
+ unlock_buffer(bh);
+ BUFFER_TRACE(bh, "return this buffer");
+ return journal_add_journal_head(bh);
+}
+
+/*
+ * Management for journal control blocks: functions to create and
+ * destroy journal_t structures, and to initialise and read existing
+ * journal blocks from disk. */
+
+/* First: create and setup a journal_t object in memory. We initialise
+ * very few fields yet: that has to wait until we have created the
+ * journal structures from from scratch, or loaded them from disk. */
+
+static journal_t * journal_init_common (void)
+{
+ journal_t *journal;
+ int err;
+
+ journal = jbd_kmalloc(sizeof(*journal), GFP_KERNEL);
+ if (!journal)
+ goto fail;
+ memset(journal, 0, sizeof(*journal));
+
+ init_waitqueue_head(&journal->j_wait_transaction_locked);
+ init_waitqueue_head(&journal->j_wait_logspace);
+ init_waitqueue_head(&journal->j_wait_done_commit);
+ init_waitqueue_head(&journal->j_wait_checkpoint);
+ init_waitqueue_head(&journal->j_wait_commit);
+ init_waitqueue_head(&journal->j_wait_updates);
+ mutex_init(&journal->j_barrier);
+ mutex_init(&journal->j_checkpoint_mutex);
+ spin_lock_init(&journal->j_revoke_lock);
+ spin_lock_init(&journal->j_list_lock);
+ spin_lock_init(&journal->j_state_lock);
+
+ journal->j_commit_interval = (HZ * JBD_DEFAULT_MAX_COMMIT_AGE);
+
+ /* The journal is marked for error until we succeed with recovery! */
+ journal->j_flags = JFS_ABORT;
+
+ /* Set up a default-sized revoke table for the new mount. */
+ err = journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
+ if (err) {
+ kfree(journal);
+ goto fail;
+ }
+ return journal;
+fail:
+ return NULL;
+}
+
+/* journal_init_dev and journal_init_inode:
+ *
+ * Create a journal structure assigned some fixed set of disk blocks to
+ * the journal. We don't actually touch those disk blocks yet, but we
+ * need to set up all of the mapping information to tell the journaling
+ * system where the journal blocks are.
+ *
+ */
+
+/**
+ * journal_t * journal_init_dev() - creates an initialises a journal structure
+ * @bdev: Block device on which to create the journal
+ * @fs_dev: Device which hold journalled filesystem for this journal.
+ * @start: Block nr Start of journal.
+ * @len: Length of the journal in blocks.
+ * @blocksize: blocksize of journalling device
+ * @returns: a newly created journal_t *
+ *
+ * journal_init_dev creates a journal which maps a fixed contiguous
+ * range of blocks on an arbitrary block device.
+ *
+ */
+journal_t * journal_init_dev(struct block_device *bdev,
+ struct block_device *fs_dev,
+ int start, int len, int blocksize)
+{
+ journal_t *journal = journal_init_common();
+ struct buffer_head *bh;
+ int n;
+
+ if (!journal)
+ return NULL;
+
+ /* journal descriptor can store up to n blocks -bzzz */
+ journal->j_blocksize = blocksize;
+ n = journal->j_blocksize / sizeof(journal_block_tag_t);
+ journal->j_wbufsize = n;
+ journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
+ if (!journal->j_wbuf) {
+ printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
+ __FUNCTION__);
+ kfree(journal);
+ journal = NULL;
+ }
+ journal->j_dev = bdev;
+ journal->j_fs_dev = fs_dev;
+ journal->j_blk_offset = start;
+ journal->j_maxlen = len;
+
+ bh = __getblk(journal->j_dev, start, journal->j_blocksize);
+ J_ASSERT(bh != NULL);
+ journal->j_sb_buffer = bh;
+ journal->j_superblock = (journal_superblock_t *)bh->b_data;
+
+ return journal;
+}
+
+/**
+ * journal_t * journal_init_inode () - creates a journal which maps to a inode.
+ * @inode: An inode to create the journal in
+ *
+ * journal_init_inode creates a journal which maps an on-disk inode as
+ * the journal. The inode must exist already, must support bmap() and
+ * must have all data blocks preallocated.
+ */
+journal_t * journal_init_inode (struct inode *inode)
+{
+ struct buffer_head *bh;
+ journal_t *journal = journal_init_common();
+ int err;
+ int n;
+ unsigned long blocknr;
+
+ if (!journal)
+ return NULL;
+
+ journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev;
+ journal->j_inode = inode;
+ jbd_debug(1,
+ "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n",
+ journal, inode->i_sb->s_id, inode->i_ino,
+ (long long) inode->i_size,
+ inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
+
+ journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
+ journal->j_blocksize = inode->i_sb->s_blocksize;
+
+ /* journal descriptor can store up to n blocks -bzzz */
+ n = journal->j_blocksize / sizeof(journal_block_tag_t);
+ journal->j_wbufsize = n;
+ journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
+ if (!journal->j_wbuf) {
+ printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
+ __FUNCTION__);
+ kfree(journal);
+ return NULL;
+ }
+
+ err = journal_bmap(journal, 0, &blocknr);
+ /* If that failed, give up */
+ if (err) {
+ printk(KERN_ERR "%s: Cannnot locate journal superblock\n",
+ __FUNCTION__);
+ kfree(journal);
+ return NULL;
+ }
+
+ bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
+ J_ASSERT(bh != NULL);
+ journal->j_sb_buffer = bh;
+ journal->j_superblock = (journal_superblock_t *)bh->b_data;
+
+ return journal;
+}
+
+/*
+ * If the journal init or create aborts, we need to mark the journal
+ * superblock as being NULL to prevent the journal destroy from writing
+ * back a bogus superblock.
+ */
+static void journal_fail_superblock (journal_t *journal)
+{
+ struct buffer_head *bh = journal->j_sb_buffer;
+ brelse(bh);
+ journal->j_sb_buffer = NULL;
+}
+
+/*
+ * Given a journal_t structure, initialise the various fields for
+ * startup of a new journaling session. We use this both when creating
+ * a journal, and after recovering an old journal to reset it for
+ * subsequent use.
+ */
+
+static int journal_reset(journal_t *journal)
+{
+ journal_superblock_t *sb = journal->j_superblock;
+ unsigned long first, last;
+
+ first = be32_to_cpu(sb->s_first);
+ last = be32_to_cpu(sb->s_maxlen);
+
+ journal->j_first = first;
+ journal->j_last = last;
+
+ journal->j_head = first;
+ journal->j_tail = first;
+ journal->j_free = last - first;
+
+ journal->j_tail_sequence = journal->j_transaction_sequence;
+ journal->j_commit_sequence = journal->j_transaction_sequence - 1;
+ journal->j_commit_request = journal->j_commit_sequence;
+
+ journal->j_max_transaction_buffers = journal->j_maxlen / 4;
+
+ /* Add the dynamic fields and write it to disk. */
+ journal_update_superblock(journal, 1);
+ journal_start_thread(journal);
+ return 0;
+}
+
+/**
+ * int journal_create() - Initialise the new journal file
+ * @journal: Journal to create. This structure must have been initialised
+ *
+ * Given a journal_t structure which tells us which disk blocks we can
+ * use, create a new journal superblock and initialise all of the
+ * journal fields from scratch.
+ **/
+int journal_create(journal_t *journal)
+{
+ unsigned long blocknr;
+ struct buffer_head *bh;
+ journal_superblock_t *sb;
+ int i, err;
+
+ if (journal->j_maxlen < JFS_MIN_JOURNAL_BLOCKS) {
+ printk (KERN_ERR "Journal length (%d blocks) too short.\n",
+ journal->j_maxlen);
+ journal_fail_superblock(journal);
+ return -EINVAL;
+ }
+
+ if (journal->j_inode == NULL) {
+ /*
+ * We don't know what block to start at!
+ */
+ printk(KERN_EMERG
+ "%s: creation of journal on external device!\n",
+ __FUNCTION__);
+ BUG();
+ }
+
+ /* Zero out the entire journal on disk. We cannot afford to
+ have any blocks on disk beginning with JFS_MAGIC_NUMBER. */
+ jbd_debug(1, "JBD: Zeroing out journal blocks...\n");
+ for (i = 0; i < journal->j_maxlen; i++) {
+ err = journal_bmap(journal, i, &blocknr);
+ if (err)
+ return err;
+ bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
+ lock_buffer(bh);
+ memset (bh->b_data, 0, journal->j_blocksize);
+ BUFFER_TRACE(bh, "marking dirty");
+ mark_buffer_dirty(bh);
+ BUFFER_TRACE(bh, "marking uptodate");
+ set_buffer_uptodate(bh);
+ unlock_buffer(bh);
+ __brelse(bh);
+ }
+
+ sync_blockdev(journal->j_dev);
+ jbd_debug(1, "JBD: journal cleared.\n");
+
+ /* OK, fill in the initial static fields in the new superblock */
+ sb = journal->j_superblock;
+
+ sb->s_header.h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
+ sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2);
+
+ sb->s_blocksize = cpu_to_be32(journal->j_blocksize);
+ sb->s_maxlen = cpu_to_be32(journal->j_maxlen);
+ sb->s_first = cpu_to_be32(1);
+
+ journal->j_transaction_sequence = 1;
+
+ journal->j_flags &= ~JFS_ABORT;
+ journal->j_format_version = 2;
+
+ return journal_reset(journal);
+}
+
+/**
+ * void journal_update_superblock() - Update journal sb on disk.
+ * @journal: The journal to update.
+ * @wait: Set to '0' if you don't want to wait for IO completion.
+ *
+ * Update a journal's dynamic superblock fields and write it to disk,
+ * optionally waiting for the IO to complete.
+ */
+void journal_update_superblock(journal_t *journal, int wait)
+{
+ journal_superblock_t *sb = journal->j_superblock;
+ struct buffer_head *bh = journal->j_sb_buffer;
+
+ /*
+ * As a special case, if the on-disk copy is already marked as needing
+ * no recovery (s_start == 0) and there are no outstanding transactions
+ * in the filesystem, then we can safely defer the superblock update
+ * until the next commit by setting JFS_FLUSHED. This avoids
+ * attempting a write to a potential-readonly device.
+ */
+ if (sb->s_start == 0 && journal->j_tail_sequence ==
+ journal->j_transaction_sequence) {
+ jbd_debug(1,"JBD: Skipping superblock update on recovered sb "
+ "(start %ld, seq %d, errno %d)\n",
+ journal->j_tail, journal->j_tail_sequence,
+ journal->j_errno);
+ goto out;
+ }
+
+ spin_lock(&journal->j_state_lock);
+ jbd_debug(1,"JBD: updating superblock (start %ld, seq %d, errno %d)\n",
+ journal->j_tail, journal->j_tail_sequence, journal->j_errno);
+
+ sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
+ sb->s_start = cpu_to_be32(journal->j_tail);
+ sb->s_errno = cpu_to_be32(journal->j_errno);
+ spin_unlock(&journal->j_state_lock);
+
+ BUFFER_TRACE(bh, "marking dirty");
+ mark_buffer_dirty(bh);
+ if (wait)
+ sync_dirty_buffer(bh);
+ else
+ ll_rw_block(SWRITE, 1, &bh);
+
+out:
+ /* If we have just flushed the log (by marking s_start==0), then
+ * any future commit will have to be careful to update the
+ * superblock again to re-record the true start of the log. */
+
+ spin_lock(&journal->j_state_lock);
+ if (sb->s_start)
+ journal->j_flags &= ~JFS_FLUSHED;
+ else
+ journal->j_flags |= JFS_FLUSHED;
+ spin_unlock(&journal->j_state_lock);
+}
+
+/*
+ * Read the superblock for a given journal, performing initial
+ * validation of the format.
+ */
+
+static int journal_get_superblock(journal_t *journal)
+{
+ struct buffer_head *bh;
+ journal_superblock_t *sb;
+ int err = -EIO;
+
+ bh = journal->j_sb_buffer;
+
+ J_ASSERT(bh != NULL);
+ if (!buffer_uptodate(bh)) {
+ ll_rw_block(READ, 1, &bh);
+ wait_on_buffer(bh);
+ if (!buffer_uptodate(bh)) {
+ printk (KERN_ERR
+ "JBD: IO error reading journal superblock\n");
+ goto out;
+ }
+ }
+
+ sb = journal->j_superblock;
+
+ err = -EINVAL;
+
+ if (sb->s_header.h_magic != cpu_to_be32(JFS_MAGIC_NUMBER) ||
+ sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) {
+ printk(KERN_WARNING "JBD: no valid journal superblock found\n");
+ goto out;
+ }
+
+ switch(be32_to_cpu(sb->s_header.h_blocktype)) {
+ case JFS_SUPERBLOCK_V1:
+ journal->j_format_version = 1;
+ break;
+ case JFS_SUPERBLOCK_V2:
+ journal->j_format_version = 2;
+ break;
+ default:
+ printk(KERN_WARNING "JBD: unrecognised superblock format ID\n");
+ goto out;
+ }
+
+ if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen)
+ journal->j_maxlen = be32_to_cpu(sb->s_maxlen);
+ else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) {
+ printk (KERN_WARNING "JBD: journal file too short\n");
+ goto out;
+ }
+
+ return 0;
+
+out:
+ journal_fail_superblock(journal);
+ return err;
+}
+
+/*
+ * Load the on-disk journal superblock and read the key fields into the
+ * journal_t.
+ */
+
+static int load_superblock(journal_t *journal)
+{
+ int err;
+ journal_superblock_t *sb;
+
+ err = journal_get_superblock(journal);
+ if (err)
+ return err;
+
+ sb = journal->j_superblock;
+
+ journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
+ journal->j_tail = be32_to_cpu(sb->s_start);
+ journal->j_first = be32_to_cpu(sb->s_first);
+ journal->j_last = be32_to_cpu(sb->s_maxlen);
+ journal->j_errno = be32_to_cpu(sb->s_errno);
+
+ return 0;
+}
+
+
+/**
+ * int journal_load() - Read journal from disk.
+ * @journal: Journal to act on.
+ *
+ * Given a journal_t structure which tells us which disk blocks contain
+ * a journal, read the journal from disk to initialise the in-memory
+ * structures.
+ */
+int journal_load(journal_t *journal)
+{
+ int err;
+ journal_superblock_t *sb;
+
+ err = load_superblock(journal);
+ if (err)
+ return err;
+
+ sb = journal->j_superblock;
+ /* If this is a V2 superblock, then we have to check the
+ * features flags on it. */
+
+ if (journal->j_format_version >= 2) {
+ if ((sb->s_feature_ro_compat &
+ ~cpu_to_be32(JFS_KNOWN_ROCOMPAT_FEATURES)) ||
+ (sb->s_feature_incompat &
+ ~cpu_to_be32(JFS_KNOWN_INCOMPAT_FEATURES))) {
+ printk (KERN_WARNING
+ "JBD: Unrecognised features on journal\n");
+ return -EINVAL;
+ }
+ }
+
+ /*
+ * Create a slab for this blocksize
+ */
+ err = journal_create_jbd_slab(be32_to_cpu(sb->s_blocksize));
+ if (err)
+ return err;
+
+ /* Let the recovery code check whether it needs to recover any
+ * data from the journal. */
+ if (journal_recover(journal))
+ goto recovery_error;
+
+ /* OK, we've finished with the dynamic journal bits:
+ * reinitialise the dynamic contents of the superblock in memory
+ * and reset them on disk. */
+ if (journal_reset(journal))
+ goto recovery_error;
+
+ journal->j_flags &= ~JFS_ABORT;
+ journal->j_flags |= JFS_LOADED;
+ return 0;
+
+recovery_error:
+ printk (KERN_WARNING "JBD: recovery failed\n");
+ return -EIO;
+}
+
+/**
+ * void journal_destroy() - Release a journal_t structure.
+ * @journal: Journal to act on.
+ *
+ * Release a journal_t structure once it is no longer in use by the
+ * journaled object.
+ */
+void journal_destroy(journal_t *journal)
+{
+ /* Wait for the commit thread to wake up and die. */
+ journal_kill_thread(journal);
+
+ /* Force a final log commit */
+ if (journal->j_running_transaction)
+ journal_commit_transaction(journal);
+
+ /* Force any old transactions to disk */
+
+ /* Totally anal locking here... */
+ spin_lock(&journal->j_list_lock);
+ while (journal->j_checkpoint_transactions != NULL) {
+ spin_unlock(&journal->j_list_lock);
+ log_do_checkpoint(journal);
+ spin_lock(&journal->j_list_lock);
+ }
+
+ J_ASSERT(journal->j_running_transaction == NULL);
+ J_ASSERT(journal->j_committing_transaction == NULL);
+ J_ASSERT(journal->j_checkpoint_transactions == NULL);
+ spin_unlock(&journal->j_list_lock);
+
+ /* We can now mark the journal as empty. */
+ journal->j_tail = 0;
+ journal->j_tail_sequence = ++journal->j_transaction_sequence;
+ if (journal->j_sb_buffer) {
+ journal_update_superblock(journal, 1);
+ brelse(journal->j_sb_buffer);
+ }
+
+ if (journal->j_inode)
+ iput(journal->j_inode);
+ if (journal->j_revoke)
+ journal_destroy_revoke(journal);
+ kfree(journal->j_wbuf);
+ kfree(journal);
+}
+
+
+/**
+ *int journal_check_used_features () - Check if features specified are used.
+ * @journal: Journal to check.
+ * @compat: bitmask of compatible features
+ * @ro: bitmask of features that force read-only mount
+ * @incompat: bitmask of incompatible features
+ *
+ * Check whether the journal uses all of a given set of
+ * features. Return true (non-zero) if it does.
+ **/
+
+int journal_check_used_features (journal_t *journal, unsigned long compat,
+ unsigned long ro, unsigned long incompat)
+{
+ journal_superblock_t *sb;
+
+ if (!compat && !ro && !incompat)
+ return 1;
+ if (journal->j_format_version == 1)
+ return 0;
+
+ sb = journal->j_superblock;
+
+ if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
+ ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
+ ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
+ return 1;
+
+ return 0;
+}
+
+/**
+ * int journal_check_available_features() - Check feature set in journalling layer
+ * @journal: Journal to check.
+ * @compat: bitmask of compatible features
+ * @ro: bitmask of features that force read-only mount
+ * @incompat: bitmask of incompatible features
+ *
+ * Check whether the journaling code supports the use of
+ * all of a given set of features on this journal. Return true
+ * (non-zero) if it can. */
+
+int journal_check_available_features (journal_t *journal, unsigned long compat,
+ unsigned long ro, unsigned long incompat)
+{
+ journal_superblock_t *sb;
+
+ if (!compat && !ro && !incompat)
+ return 1;
+
+ sb = journal->j_superblock;
+
+ /* We can support any known requested features iff the
+ * superblock is in version 2. Otherwise we fail to support any
+ * extended sb features. */
+
+ if (journal->j_format_version != 2)
+ return 0;
+
+ if ((compat & JFS_KNOWN_COMPAT_FEATURES) == compat &&
+ (ro & JFS_KNOWN_ROCOMPAT_FEATURES) == ro &&
+ (incompat & JFS_KNOWN_INCOMPAT_FEATURES) == incompat)
+ return 1;
+
+ return 0;
+}
+
+/**
+ * int journal_set_features () - Mark a given journal feature in the superblock
+ * @journal: Journal to act on.
+ * @compat: bitmask of compatible features
+ * @ro: bitmask of features that force read-only mount
+ * @incompat: bitmask of incompatible features
+ *
+ * Mark a given journal feature as present on the
+ * superblock. Returns true if the requested features could be set.
+ *
+ */
+
+int journal_set_features (journal_t *journal, unsigned long compat,
+ unsigned long ro, unsigned long incompat)
+{
+ journal_superblock_t *sb;
+
+ if (journal_check_used_features(journal, compat, ro, incompat))
+ return 1;
+
+ if (!journal_check_available_features(journal, compat, ro, incompat))
+ return 0;
+
+ jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
+ compat, ro, incompat);
+
+ sb = journal->j_superblock;
+
+ sb->s_feature_compat |= cpu_to_be32(compat);
+ sb->s_feature_ro_compat |= cpu_to_be32(ro);
+ sb->s_feature_incompat |= cpu_to_be32(incompat);
+
+ return 1;
+}
+
+
+/**
+ * int journal_update_format () - Update on-disk journal structure.
+ * @journal: Journal to act on.
+ *
+ * Given an initialised but unloaded journal struct, poke about in the
+ * on-disk structure to update it to the most recent supported version.
+ */
+int journal_update_format (journal_t *journal)
+{
+ journal_superblock_t *sb;
+ int err;
+
+ err = journal_get_superblock(journal);
+ if (err)
+ return err;
+
+ sb = journal->j_superblock;
+
+ switch (be32_to_cpu(sb->s_header.h_blocktype)) {
+ case JFS_SUPERBLOCK_V2:
+ return 0;
+ case JFS_SUPERBLOCK_V1:
+ return journal_convert_superblock_v1(journal, sb);
+ default:
+ break;
+ }
+ return -EINVAL;
+}
+
+static int journal_convert_superblock_v1(journal_t *journal,
+ journal_superblock_t *sb)
+{
+ int offset, blocksize;
+ struct buffer_head *bh;
+
+ printk(KERN_WARNING
+ "JBD: Converting superblock from version 1 to 2.\n");
+
+ /* Pre-initialise new fields to zero */
+ offset = ((char *) &(sb->s_feature_compat)) - ((char *) sb);
+ blocksize = be32_to_cpu(sb->s_blocksize);
+ memset(&sb->s_feature_compat, 0, blocksize-offset);
+
+ sb->s_nr_users = cpu_to_be32(1);
+ sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2);
+ journal->j_format_version = 2;
+
+ bh = journal->j_sb_buffer;
+ BUFFER_TRACE(bh, "marking dirty");
+ mark_buffer_dirty(bh);
+ sync_dirty_buffer(bh);
+ return 0;
+}
+
+
+/**
+ * int journal_flush () - Flush journal
+ * @journal: Journal to act on.
+ *
+ * Flush all data for a given journal to disk and empty the journal.
+ * Filesystems can use this when remounting readonly to ensure that
+ * recovery does not need to happen on remount.
+ */
+
+int journal_flush(journal_t *journal)
+{
+ int err = 0;
+ transaction_t *transaction = NULL;
+ unsigned long old_tail;
+
+ spin_lock(&journal->j_state_lock);
+
+ /* Force everything buffered to the log... */
+ if (journal->j_running_transaction) {
+ transaction = journal->j_running_transaction;
+ __log_start_commit(journal, transaction->t_tid);
+ } else if (journal->j_committing_transaction)
+ transaction = journal->j_committing_transaction;
+
+ /* Wait for the log commit to complete... */
+ if (transaction) {
+ tid_t tid = transaction->t_tid;
+
+ spin_unlock(&journal->j_state_lock);
+ log_wait_commit(journal, tid);
+ } else {
+ spin_unlock(&journal->j_state_lock);
+ }
+
+ /* ...and flush everything in the log out to disk. */
+ spin_lock(&journal->j_list_lock);
+ while (!err && journal->j_checkpoint_transactions != NULL) {
+ spin_unlock(&journal->j_list_lock);
+ err = log_do_checkpoint(journal);
+ spin_lock(&journal->j_list_lock);
+ }
+ spin_unlock(&journal->j_list_lock);
+ cleanup_journal_tail(journal);
+
+ /* Finally, mark the journal as really needing no recovery.
+ * This sets s_start==0 in the underlying superblock, which is
+ * the magic code for a fully-recovered superblock. Any future
+ * commits of data to the journal will restore the current
+ * s_start value. */
+ spin_lock(&journal->j_state_lock);
+ old_tail = journal->j_tail;
+ journal->j_tail = 0;
+ spin_unlock(&journal->j_state_lock);
+ journal_update_superblock(journal, 1);
+ spin_lock(&journal->j_state_lock);
+ journal->j_tail = old_tail;
+
+ J_ASSERT(!journal->j_running_transaction);
+ J_ASSERT(!journal->j_committing_transaction);
+ J_ASSERT(!journal->j_checkpoint_transactions);
+ J_ASSERT(journal->j_head == journal->j_tail);
+ J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
+ spin_unlock(&journal->j_state_lock);
+ return err;
+}
+
+/**
+ * int journal_wipe() - Wipe journal contents
+ * @journal: Journal to act on.
+ * @write: flag (see below)
+ *
+ * Wipe out all of the contents of a journal, safely. This will produce
+ * a warning if the journal contains any valid recovery information.
+ * Must be called between journal_init_*() and journal_load().
+ *
+ * If 'write' is non-zero, then we wipe out the journal on disk; otherwise
+ * we merely suppress recovery.
+ */
+
+int journal_wipe(journal_t *journal, int write)
+{
+ journal_superblock_t *sb;
+ int err = 0;
+
+ J_ASSERT (!(journal->j_flags & JFS_LOADED));
+
+ err = load_superblock(journal);
+ if (err)
+ return err;
+
+ sb = journal->j_superblock;
+
+ if (!journal->j_tail)
+ goto no_recovery;
+
+ printk (KERN_WARNING "JBD: %s recovery information on journal\n",
+ write ? "Clearing" : "Ignoring");
+
+ err = journal_skip_recovery(journal);
+ if (write)
+ journal_update_superblock(journal, 1);
+
+ no_recovery:
+ return err;
+}
+
+/*
+ * journal_dev_name: format a character string to describe on what
+ * device this journal is present.
+ */
+
+static const char *journal_dev_name(journal_t *journal, char *buffer)
+{
+ struct block_device *bdev;
+
+ if (journal->j_inode)
+ bdev = journal->j_inode->i_sb->s_bdev;
+ else
+ bdev = journal->j_dev;
+
+ return bdevname(bdev, buffer);
+}
+
+/*
+ * Journal abort has very specific semantics, which we describe
+ * for journal abort.
+ *
+ * Two internal function, which provide abort to te jbd layer
+ * itself are here.
+ */
+
+/*
+ * Quick version for internal journal use (doesn't lock the journal).
+ * Aborts hard --- we mark the abort as occurred, but do _nothing_ else,
+ * and don't attempt to make any other journal updates.
+ */
+void __journal_abort_hard(journal_t *journal)
+{
+ transaction_t *transaction;
+ char b[BDEVNAME_SIZE];
+
+ if (journal->j_flags & JFS_ABORT)
+ return;
+
+ printk(KERN_ERR "Aborting journal on device %s.\n",
+ journal_dev_name(journal, b));
+
+ spin_lock(&journal->j_state_lock);
+ journal->j_flags |= JFS_ABORT;
+ transaction = journal->j_running_transaction;
+ if (transaction)
+ __log_start_commit(journal, transaction->t_tid);
+ spin_unlock(&journal->j_state_lock);
+}
+
+/* Soft abort: record the abort error status in the journal superblock,
+ * but don't do any other IO. */
+static void __journal_abort_soft (journal_t *journal, int errno)
+{
+ if (journal->j_flags & JFS_ABORT)
+ return;
+
+ if (!journal->j_errno)
+ journal->j_errno = errno;
+
+ __journal_abort_hard(journal);
+
+ if (errno)
+ journal_update_superblock(journal, 1);
+}
+
+/**
+ * void journal_abort () - Shutdown the journal immediately.
+ * @journal: the journal to shutdown.
+ * @errno: an error number to record in the journal indicating
+ * the reason for the shutdown.
+ *
+ * Perform a complete, immediate shutdown of the ENTIRE
+ * journal (not of a single transaction). This operation cannot be
+ * undone without closing and reopening the journal.
+ *
+ * The journal_abort function is intended to support higher level error
+ * recovery mechanisms such as the ext2/ext3 remount-readonly error
+ * mode.
+ *
+ * Journal abort has very specific semantics. Any existing dirty,
+ * unjournaled buffers in the main filesystem will still be written to
+ * disk by bdflush, but the journaling mechanism will be suspended
+ * immediately and no further transaction commits will be honoured.
+ *
+ * Any dirty, journaled buffers will be written back to disk without
+ * hitting the journal. Atomicity cannot be guaranteed on an aborted
+ * filesystem, but we _do_ attempt to leave as much data as possible
+ * behind for fsck to use for cleanup.
+ *
+ * Any attempt to get a new transaction handle on a journal which is in
+ * ABORT state will just result in an -EROFS error return. A
+ * journal_stop on an existing handle will return -EIO if we have
+ * entered abort state during the update.
+ *
+ * Recursive transactions are not disturbed by journal abort until the
+ * final journal_stop, which will receive the -EIO error.
+ *
+ * Finally, the journal_abort call allows the caller to supply an errno
+ * which will be recorded (if possible) in the journal superblock. This
+ * allows a client to record failure conditions in the middle of a
+ * transaction without having to complete the transaction to record the
+ * failure to disk. ext3_error, for example, now uses this
+ * functionality.
+ *
+ * Errors which originate from within the journaling layer will NOT
+ * supply an errno; a null errno implies that absolutely no further
+ * writes are done to the journal (unless there are any already in
+ * progress).
+ *
+ */
+
+void journal_abort(journal_t *journal, int errno)
+{
+ __journal_abort_soft(journal, errno);
+}
+
+/**
+ * int journal_errno () - returns the journal's error state.
+ * @journal: journal to examine.
+ *
+ * This is the errno numbet set with journal_abort(), the last
+ * time the journal was mounted - if the journal was stopped
+ * without calling abort this will be 0.
+ *
+ * If the journal has been aborted on this mount time -EROFS will
+ * be returned.
+ */
+int journal_errno(journal_t *journal)
+{
+ int err;
+
+ spin_lock(&journal->j_state_lock);
+ if (journal->j_flags & JFS_ABORT)
+ err = -EROFS;
+ else
+ err = journal->j_errno;
+ spin_unlock(&journal->j_state_lock);
+ return err;
+}
+
+/**
+ * int journal_clear_err () - clears the journal's error state
+ * @journal: journal to act on.
+ *
+ * An error must be cleared or Acked to take a FS out of readonly
+ * mode.
+ */
+int journal_clear_err(journal_t *journal)
+{
+ int err = 0;
+
+ spin_lock(&journal->j_state_lock);
+ if (journal->j_flags & JFS_ABORT)
+ err = -EROFS;
+ else
+ journal->j_errno = 0;
+ spin_unlock(&journal->j_state_lock);
+ return err;
+}
+
+/**
+ * void journal_ack_err() - Ack journal err.
+ * @journal: journal to act on.
+ *
+ * An error must be cleared or Acked to take a FS out of readonly
+ * mode.
+ */
+void journal_ack_err(journal_t *journal)
+{
+ spin_lock(&journal->j_state_lock);
+ if (journal->j_errno)
+ journal->j_flags |= JFS_ACK_ERR;
+ spin_unlock(&journal->j_state_lock);
+}
+
+int journal_blocks_per_page(struct inode *inode)
+{
+ return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
+}
+
+/*
+ * Simple support for retrying memory allocations. Introduced to help to
+ * debug different VM deadlock avoidance strategies.
+ */
+void * __jbd_kmalloc (const char *where, size_t size, gfp_t flags, int retry)
+{
+ return kmalloc(size, flags | (retry ? __GFP_NOFAIL : 0));
+}
+
+/*
+ * jbd slab management: create 1k, 2k, 4k, 8k slabs as needed
+ * and allocate frozen and commit buffers from these slabs.
+ *
+ * Reason for doing this is to avoid, SLAB_DEBUG - since it could
+ * cause bh to cross page boundary.
+ */
+
+#define JBD_MAX_SLABS 5
+#define JBD_SLAB_INDEX(size) (size >> 11)
+
+static kmem_cache_t *jbd_slab[JBD_MAX_SLABS];
+static const char *jbd_slab_names[JBD_MAX_SLABS] = {
+ "jbd_1k", "jbd_2k", "jbd_4k", NULL, "jbd_8k"
+};
+
+static void journal_destroy_jbd_slabs(void)
+{
+ int i;
+
+ for (i = 0; i < JBD_MAX_SLABS; i++) {
+ if (jbd_slab[i])
+ kmem_cache_destroy(jbd_slab[i]);
+ jbd_slab[i] = NULL;
+ }
+}
+
+static int journal_create_jbd_slab(size_t slab_size)
+{
+ int i = JBD_SLAB_INDEX(slab_size);
+
+ BUG_ON(i >= JBD_MAX_SLABS);
+
+ /*
+ * Check if we already have a slab created for this size
+ */
+ if (jbd_slab[i])
+ return 0;
+
+ /*
+ * Create a slab and force alignment to be same as slabsize -
+ * this will make sure that allocations won't cross the page
+ * boundary.
+ */
+ jbd_slab[i] = kmem_cache_create(jbd_slab_names[i],
+ slab_size, slab_size, 0, NULL, NULL);
+ if (!jbd_slab[i]) {
+ printk(KERN_EMERG "JBD: no memory for jbd_slab cache\n");
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+void * jbd_slab_alloc(size_t size, gfp_t flags)
+{
+ int idx;
+
+ idx = JBD_SLAB_INDEX(size);
+ BUG_ON(jbd_slab[idx] == NULL);
+ return kmem_cache_alloc(jbd_slab[idx], flags | __GFP_NOFAIL);
+}
+
+void jbd_slab_free(void *ptr, size_t size)
+{
+ int idx;
+
+ idx = JBD_SLAB_INDEX(size);
+ BUG_ON(jbd_slab[idx] == NULL);
+ kmem_cache_free(jbd_slab[idx], ptr);
+}
+
+/*
+ * Journal_head storage management
+ */
+static kmem_cache_t *journal_head_cache;
+#ifdef CONFIG_JBD_DEBUG
+static atomic_t nr_journal_heads = ATOMIC_INIT(0);
+#endif
+
+static int journal_init_journal_head_cache(void)
+{
+ int retval;
+
+ J_ASSERT(journal_head_cache == 0);
+ journal_head_cache = kmem_cache_create("journal_head",
+ sizeof(struct journal_head),
+ 0, /* offset */
+ 0, /* flags */
+ NULL, /* ctor */
+ NULL); /* dtor */
+ retval = 0;
+ if (journal_head_cache == 0) {
+ retval = -ENOMEM;
+ printk(KERN_EMERG "JBD: no memory for journal_head cache\n");
+ }
+ return retval;
+}
+
+static void journal_destroy_journal_head_cache(void)
+{
+ J_ASSERT(journal_head_cache != NULL);
+ kmem_cache_destroy(journal_head_cache);
+ journal_head_cache = NULL;
+}
+
+/*
+ * journal_head splicing and dicing
+ */
+static struct journal_head *journal_alloc_journal_head(void)
+{
+ struct journal_head *ret;
+ static unsigned long last_warning;
+
+#ifdef CONFIG_JBD_DEBUG
+ atomic_inc(&nr_journal_heads);
+#endif
+ ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS);
+ if (ret == 0) {
+ jbd_debug(1, "out of memory for journal_head\n");
+ if (time_after(jiffies, last_warning + 5*HZ)) {
+ printk(KERN_NOTICE "ENOMEM in %s, retrying.\n",
+ __FUNCTION__);
+ last_warning = jiffies;
+ }
+ while (ret == 0) {
+ yield();
+ ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS);
+ }
+ }
+ return ret;
+}
+
+static void journal_free_journal_head(struct journal_head *jh)
+{
+#ifdef CONFIG_JBD_DEBUG
+ atomic_dec(&nr_journal_heads);
+ memset(jh, JBD_POISON_FREE, sizeof(*jh));
+#endif
+ kmem_cache_free(journal_head_cache, jh);
+}
+
+/*
+ * A journal_head is attached to a buffer_head whenever JBD has an
+ * interest in the buffer.
+ *
+ * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
+ * is set. This bit is tested in core kernel code where we need to take
+ * JBD-specific actions. Testing the zeroness of ->b_private is not reliable
+ * there.
+ *
+ * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
+ *
+ * When a buffer has its BH_JBD bit set it is immune from being released by
+ * core kernel code, mainly via ->b_count.
+ *
+ * A journal_head may be detached from its buffer_head when the journal_head's
+ * b_transaction, b_cp_transaction and b_next_transaction pointers are NULL.
+ * Various places in JBD call journal_remove_journal_head() to indicate that the
+ * journal_head can be dropped if needed.
+ *
+ * Various places in the kernel want to attach a journal_head to a buffer_head
+ * _before_ attaching the journal_head to a transaction. To protect the
+ * journal_head in this situation, journal_add_journal_head elevates the
+ * journal_head's b_jcount refcount by one. The caller must call
+ * journal_put_journal_head() to undo this.
+ *
+ * So the typical usage would be:
+ *
+ * (Attach a journal_head if needed. Increments b_jcount)
+ * struct journal_head *jh = journal_add_journal_head(bh);
+ * ...
+ * jh->b_transaction = xxx;
+ * journal_put_journal_head(jh);
+ *
+ * Now, the journal_head's b_jcount is zero, but it is safe from being released
+ * because it has a non-zero b_transaction.
+ */
+
+/*
+ * Give a buffer_head a journal_head.
+ *
+ * Doesn't need the journal lock.
+ * May sleep.
+ */
+struct journal_head *journal_add_journal_head(struct buffer_head *bh)
+{
+ struct journal_head *jh;
+ struct journal_head *new_jh = NULL;
+
+repeat:
+ if (!buffer_jbd(bh)) {
+ new_jh = journal_alloc_journal_head();
+ memset(new_jh, 0, sizeof(*new_jh));
+ }
+
+ jbd_lock_bh_journal_head(bh);
+ if (buffer_jbd(bh)) {
+ jh = bh2jh(bh);
+ } else {
+ J_ASSERT_BH(bh,
+ (atomic_read(&bh->b_count) > 0) ||
+ (bh->b_page && bh->b_page->mapping));
+
+ if (!new_jh) {
+ jbd_unlock_bh_journal_head(bh);
+ goto repeat;
+ }
+
+ jh = new_jh;
+ new_jh = NULL; /* We consumed it */
+ set_buffer_jbd(bh);
+ bh->b_private = jh;
+ jh->b_bh = bh;
+ get_bh(bh);
+ BUFFER_TRACE(bh, "added journal_head");
+ }
+ jh->b_jcount++;
+ jbd_unlock_bh_journal_head(bh);
+ if (new_jh)
+ journal_free_journal_head(new_jh);
+ return bh->b_private;
+}
+
+/*
+ * Grab a ref against this buffer_head's journal_head. If it ended up not
+ * having a journal_head, return NULL
+ */
+struct journal_head *journal_grab_journal_head(struct buffer_head *bh)
+{
+ struct journal_head *jh = NULL;
+
+ jbd_lock_bh_journal_head(bh);
+ if (buffer_jbd(bh)) {
+ jh = bh2jh(bh);
+ jh->b_jcount++;
+ }
+ jbd_unlock_bh_journal_head(bh);
+ return jh;
+}
+
+static void __journal_remove_journal_head(struct buffer_head *bh)
+{
+ struct journal_head *jh = bh2jh(bh);
+
+ J_ASSERT_JH(jh, jh->b_jcount >= 0);
+
+ get_bh(bh);
+ if (jh->b_jcount == 0) {
+ if (jh->b_transaction == NULL &&
+ jh->b_next_transaction == NULL &&
+ jh->b_cp_transaction == NULL) {
+ J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
+ J_ASSERT_BH(bh, buffer_jbd(bh));
+ J_ASSERT_BH(bh, jh2bh(jh) == bh);
+ BUFFER_TRACE(bh, "remove journal_head");
+ if (jh->b_frozen_data) {
+ printk(KERN_WARNING "%s: freeing "
+ "b_frozen_data\n",
+ __FUNCTION__);
+ jbd_slab_free(jh->b_frozen_data, bh->b_size);
+ }
+ if (jh->b_committed_data) {
+ printk(KERN_WARNING "%s: freeing "
+ "b_committed_data\n",
+ __FUNCTION__);
+ jbd_slab_free(jh->b_committed_data, bh->b_size);
+ }
+ bh->b_private = NULL;
+ jh->b_bh = NULL; /* debug, really */
+ clear_buffer_jbd(bh);
+ __brelse(bh);
+ journal_free_journal_head(jh);
+ } else {
+ BUFFER_TRACE(bh, "journal_head was locked");
+ }
+ }
+}
+
+/*
+ * journal_remove_journal_head(): if the buffer isn't attached to a transaction
+ * and has a zero b_jcount then remove and release its journal_head. If we did
+ * see that the buffer is not used by any transaction we also "logically"
+ * decrement ->b_count.
+ *
+ * We in fact take an additional increment on ->b_count as a convenience,
+ * because the caller usually wants to do additional things with the bh
+ * after calling here.
+ * The caller of journal_remove_journal_head() *must* run __brelse(bh) at some
+ * time. Once the caller has run __brelse(), the buffer is eligible for
+ * reaping by try_to_free_buffers().
+ */
+void journal_remove_journal_head(struct buffer_head *bh)
+{
+ jbd_lock_bh_journal_head(bh);
+ __journal_remove_journal_head(bh);
+ jbd_unlock_bh_journal_head(bh);
+}
+
+/*
+ * Drop a reference on the passed journal_head. If it fell to zero then try to
+ * release the journal_head from the buffer_head.
+ */
+void journal_put_journal_head(struct journal_head *jh)
+{
+ struct buffer_head *bh = jh2bh(jh);
+
+ jbd_lock_bh_journal_head(bh);
+ J_ASSERT_JH(jh, jh->b_jcount > 0);
+ --jh->b_jcount;
+ if (!jh->b_jcount && !jh->b_transaction) {
+ __journal_remove_journal_head(bh);
+ __brelse(bh);
+ }
+ jbd_unlock_bh_journal_head(bh);
+}
+
+/*
+ * /proc tunables
+ */
+#if defined(CONFIG_JBD_DEBUG)
+int journal_enable_debug;
+EXPORT_SYMBOL(journal_enable_debug);
+#endif
+
+#if defined(CONFIG_JBD_DEBUG) && defined(CONFIG_PROC_FS)
+
+static struct proc_dir_entry *proc_jbd_debug;
+
+static int read_jbd_debug(char *page, char **start, off_t off,
+ int count, int *eof, void *data)
+{
+ int ret;
+
+ ret = sprintf(page + off, "%d\n", journal_enable_debug);
+ *eof = 1;
+ return ret;
+}
+
+static int write_jbd_debug(struct file *file, const char __user *buffer,
+ unsigned long count, void *data)
+{
+ char buf[32];
+
+ if (count > ARRAY_SIZE(buf) - 1)
+ count = ARRAY_SIZE(buf) - 1;
+ if (copy_from_user(buf, buffer, count))
+ return -EFAULT;
+ buf[ARRAY_SIZE(buf) - 1] = '\0';
+ journal_enable_debug = simple_strtoul(buf, NULL, 10);
+ return count;
+}
+
+#define JBD_PROC_NAME "sys/fs/jbd-debug"
+
+static void __init create_jbd_proc_entry(void)
+{
+ proc_jbd_debug = create_proc_entry(JBD_PROC_NAME, 0644, NULL);
+ if (proc_jbd_debug) {
+ /* Why is this so hard? */
+ proc_jbd_debug->read_proc = read_jbd_debug;
+ proc_jbd_debug->write_proc = write_jbd_debug;
+ }
+}
+
+static void __exit remove_jbd_proc_entry(void)
+{
+ if (proc_jbd_debug)
+ remove_proc_entry(JBD_PROC_NAME, NULL);
+}
+
+#else
+
+#define create_jbd_proc_entry() do {} while (0)
+#define remove_jbd_proc_entry() do {} while (0)
+
+#endif
+
+kmem_cache_t *jbd_handle_cache;
+
+static int __init journal_init_handle_cache(void)
+{
+ jbd_handle_cache = kmem_cache_create("journal_handle",
+ sizeof(handle_t),
+ 0, /* offset */
+ 0, /* flags */
+ NULL, /* ctor */
+ NULL); /* dtor */
+ if (jbd_handle_cache == NULL) {
+ printk(KERN_EMERG "JBD: failed to create handle cache\n");
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+static void journal_destroy_handle_cache(void)
+{
+ if (jbd_handle_cache)
+ kmem_cache_destroy(jbd_handle_cache);
+}
+
+/*
+ * Module startup and shutdown
+ */
+
+static int __init journal_init_caches(void)
+{
+ int ret;
+
+ ret = journal_init_revoke_caches();
+ if (ret == 0)
+ ret = journal_init_journal_head_cache();
+ if (ret == 0)
+ ret = journal_init_handle_cache();
+ return ret;
+}
+
+static void journal_destroy_caches(void)
+{
+ journal_destroy_revoke_caches();
+ journal_destroy_journal_head_cache();
+ journal_destroy_handle_cache();
+ journal_destroy_jbd_slabs();
+}
+
+static int __init journal_init(void)
+{
+ int ret;
+
+ BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
+
+ ret = journal_init_caches();
+ if (ret != 0)
+ journal_destroy_caches();
+ create_jbd_proc_entry();
+ return ret;
+}
+
+static void __exit journal_exit(void)
+{
+#ifdef CONFIG_JBD_DEBUG
+ int n = atomic_read(&nr_journal_heads);
+ if (n)
+ printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
+#endif
+ remove_jbd_proc_entry();
+ journal_destroy_caches();
+}
+
+MODULE_LICENSE("GPL");
+module_init(journal_init);
+module_exit(journal_exit);
+
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
new file mode 100644
index 00000000000..11563fe2a52
--- /dev/null
+++ b/fs/jbd2/recovery.c
@@ -0,0 +1,592 @@
+/*
+ * linux/fs/recovery.c
+ *
+ * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
+ *
+ * Copyright 1999-2000 Red Hat Software --- All Rights Reserved
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * Journal recovery routines for the generic filesystem journaling code;
+ * part of the ext2fs journaling system.
+ */
+
+#ifndef __KERNEL__
+#include "jfs_user.h"
+#else
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/jbd.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#endif
+
+/*
+ * Maintain information about the progress of the recovery job, so that
+ * the different passes can carry information between them.
+ */
+struct recovery_info
+{
+ tid_t start_transaction;
+ tid_t end_transaction;
+
+ int nr_replays;
+ int nr_revokes;
+ int nr_revoke_hits;
+};
+
+enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
+static int do_one_pass(journal_t *journal,
+ struct recovery_info *info, enum passtype pass);
+static int scan_revoke_records(journal_t *, struct buffer_head *,
+ tid_t, struct recovery_info *);
+
+#ifdef __KERNEL__
+
+/* Release readahead buffers after use */
+static void journal_brelse_array(struct buffer_head *b[], int n)
+{
+ while (--n >= 0)
+ brelse (b[n]);
+}
+
+
+/*
+ * When reading from the journal, we are going through the block device
+ * layer directly and so there is no readahead being done for us. We
+ * need to implement any readahead ourselves if we want it to happen at
+ * all. Recovery is basically one long sequential read, so make sure we
+ * do the IO in reasonably large chunks.
+ *
+ * This is not so critical that we need to be enormously clever about
+ * the readahead size, though. 128K is a purely arbitrary, good-enough
+ * fixed value.
+ */
+
+#define MAXBUF 8
+static int do_readahead(journal_t *journal, unsigned int start)
+{
+ int err;
+ unsigned int max, nbufs, next;
+ unsigned long blocknr;
+ struct buffer_head *bh;
+
+ struct buffer_head * bufs[MAXBUF];
+
+ /* Do up to 128K of readahead */
+ max = start + (128 * 1024 / journal->j_blocksize);
+ if (max > journal->j_maxlen)
+ max = journal->j_maxlen;
+
+ /* Do the readahead itself. We'll submit MAXBUF buffer_heads at
+ * a time to the block device IO layer. */
+
+ nbufs = 0;
+
+ for (next = start; next < max; next++) {
+ err = journal_bmap(journal, next, &blocknr);
+
+ if (err) {
+ printk (KERN_ERR "JBD: bad block at offset %u\n",
+ next);
+ goto failed;
+ }
+
+ bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
+ if (!bh) {
+ err = -ENOMEM;
+ goto failed;
+ }
+
+ if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
+ bufs[nbufs++] = bh;
+ if (nbufs == MAXBUF) {
+ ll_rw_block(READ, nbufs, bufs);
+ journal_brelse_array(bufs, nbufs);
+ nbufs = 0;
+ }
+ } else
+ brelse(bh);
+ }
+
+ if (nbufs)
+ ll_rw_block(READ, nbufs, bufs);
+ err = 0;
+
+failed:
+ if (nbufs)
+ journal_brelse_array(bufs, nbufs);
+ return err;
+}
+
+#endif /* __KERNEL__ */
+
+
+/*
+ * Read a block from the journal
+ */
+
+static int jread(struct buffer_head **bhp, journal_t *journal,
+ unsigned int offset)
+{
+ int err;
+ unsigned long blocknr;
+ struct buffer_head *bh;
+
+ *bhp = NULL;
+
+ if (offset >= journal->j_maxlen) {
+ printk(KERN_ERR "JBD: corrupted journal superblock\n");
+ return -EIO;
+ }
+
+ err = journal_bmap(journal, offset, &blocknr);
+
+ if (err) {
+ printk (KERN_ERR "JBD: bad block at offset %u\n",
+ offset);
+ return err;
+ }
+
+ bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
+ if (!bh)
+ return -ENOMEM;
+
+ if (!buffer_uptodate(bh)) {
+ /* If this is a brand new buffer, start readahead.
+ Otherwise, we assume we are already reading it. */
+ if (!buffer_req(bh))
+ do_readahead(journal, offset);
+ wait_on_buffer(bh);
+ }
+
+ if (!buffer_uptodate(bh)) {
+ printk (KERN_ERR "JBD: Failed to read block at offset %u\n",
+ offset);
+ brelse(bh);
+ return -EIO;
+ }
+
+ *bhp = bh;
+ return 0;
+}
+
+
+/*
+ * Count the number of in-use tags in a journal descriptor block.
+ */
+
+static int count_tags(struct buffer_head *bh, int size)
+{
+ char * tagp;
+ journal_block_tag_t * tag;
+ int nr = 0;
+
+ tagp = &bh->b_data[sizeof(journal_header_t)];
+
+ while ((tagp - bh->b_data + sizeof(journal_block_tag_t)) <= size) {
+ tag = (journal_block_tag_t *) tagp;
+
+ nr++;
+ tagp += sizeof(journal_block_tag_t);
+ if (!(tag->t_flags & cpu_to_be32(JFS_FLAG_SAME_UUID)))
+ tagp += 16;
+
+ if (tag->t_flags & cpu_to_be32(JFS_FLAG_LAST_TAG))
+ break;
+ }
+
+ return nr;
+}
+
+
+/* Make sure we wrap around the log correctly! */
+#define wrap(journal, var) \
+do { \
+ if (var >= (journal)->j_last) \
+ var -= ((journal)->j_last - (journal)->j_first); \
+} while (0)
+
+/**
+ * journal_recover - recovers a on-disk journal
+ * @journal: the journal to recover
+ *
+ * The primary function for recovering the log contents when mounting a
+ * journaled device.
+ *
+ * Recovery is done in three passes. In the first pass, we look for the
+ * end of the log. In the second, we assemble the list of revoke
+ * blocks. In the third and final pass, we replay any un-revoked blocks
+ * in the log.
+ */
+int journal_recover(journal_t *journal)
+{
+ int err;
+ journal_superblock_t * sb;
+
+ struct recovery_info info;
+
+ memset(&info, 0, sizeof(info));
+ sb = journal->j_superblock;
+
+ /*
+ * The journal superblock's s_start field (the current log head)
+ * is always zero if, and only if, the journal was cleanly
+ * unmounted.
+ */
+
+ if (!sb->s_start) {
+ jbd_debug(1, "No recovery required, last transaction %d\n",
+ be32_to_cpu(sb->s_sequence));
+ journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
+ return 0;
+ }
+
+ err = do_one_pass(journal, &info, PASS_SCAN);
+ if (!err)
+ err = do_one_pass(journal, &info, PASS_REVOKE);
+ if (!err)
+ err = do_one_pass(journal, &info, PASS_REPLAY);
+
+ jbd_debug(0, "JBD: recovery, exit status %d, "
+ "recovered transactions %u to %u\n",
+ err, info.start_transaction, info.end_transaction);
+ jbd_debug(0, "JBD: Replayed %d and revoked %d/%d blocks\n",
+ info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
+
+ /* Restart the log at the next transaction ID, thus invalidating
+ * any existing commit records in the log. */
+ journal->j_transaction_sequence = ++info.end_transaction;
+
+ journal_clear_revoke(journal);
+ sync_blockdev(journal->j_fs_dev);
+ return err;
+}
+
+/**
+ * journal_skip_recovery - Start journal and wipe exiting records
+ * @journal: journal to startup
+ *
+ * Locate any valid recovery information from the journal and set up the
+ * journal structures in memory to ignore it (presumably because the
+ * caller has evidence that it is out of date).
+ * This function does'nt appear to be exorted..
+ *
+ * We perform one pass over the journal to allow us to tell the user how
+ * much recovery information is being erased, and to let us initialise
+ * the journal transaction sequence numbers to the next unused ID.
+ */
+int journal_skip_recovery(journal_t *journal)
+{
+ int err;
+ journal_superblock_t * sb;
+
+ struct recovery_info info;
+
+ memset (&info, 0, sizeof(info));
+ sb = journal->j_superblock;
+
+ err = do_one_pass(journal, &info, PASS_SCAN);
+
+ if (err) {
+ printk(KERN_ERR "JBD: error %d scanning journal\n", err);
+ ++journal->j_transaction_sequence;
+ } else {
+#ifdef CONFIG_JBD_DEBUG
+ int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence);
+#endif
+ jbd_debug(0,
+ "JBD: ignoring %d transaction%s from the journal.\n",
+ dropped, (dropped == 1) ? "" : "s");
+ journal->j_transaction_sequence = ++info.end_transaction;
+ }
+
+ journal->j_tail = 0;
+ return err;
+}
+
+static int do_one_pass(journal_t *journal,
+ struct recovery_info *info, enum passtype pass)
+{
+ unsigned int first_commit_ID, next_commit_ID;
+ unsigned long next_log_block;
+ int err, success = 0;
+ journal_superblock_t * sb;
+ journal_header_t * tmp;
+ struct buffer_head * bh;
+ unsigned int sequence;
+ int blocktype;
+
+ /* Precompute the maximum metadata descriptors in a descriptor block */
+ int MAX_BLOCKS_PER_DESC;
+ MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t))
+ / sizeof(journal_block_tag_t));
+
+ /*
+ * First thing is to establish what we expect to find in the log
+ * (in terms of transaction IDs), and where (in terms of log
+ * block offsets): query the superblock.
+ */
+
+ sb = journal->j_superblock;
+ next_commit_ID = be32_to_cpu(sb->s_sequence);
+ next_log_block = be32_to_cpu(sb->s_start);
+
+ first_commit_ID = next_commit_ID;
+ if (pass == PASS_SCAN)
+ info->start_transaction = first_commit_ID;
+
+ jbd_debug(1, "Starting recovery pass %d\n", pass);
+
+ /*
+ * Now we walk through the log, transaction by transaction,
+ * making sure that each transaction has a commit block in the
+ * expected place. Each complete transaction gets replayed back
+ * into the main filesystem.
+ */
+
+ while (1) {
+ int flags;
+ char * tagp;
+ journal_block_tag_t * tag;
+ struct buffer_head * obh;
+ struct buffer_head * nbh;
+
+ cond_resched(); /* We're under lock_kernel() */
+
+ /* If we already know where to stop the log traversal,
+ * check right now that we haven't gone past the end of
+ * the log. */
+
+ if (pass != PASS_SCAN)
+ if (tid_geq(next_commit_ID, info->end_transaction))
+ break;
+
+ jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
+ next_commit_ID, next_log_block, journal->j_last);
+
+ /* Skip over each chunk of the transaction looking
+ * either the next descriptor block or the final commit
+ * record. */
+
+ jbd_debug(3, "JBD: checking block %ld\n", next_log_block);
+ err = jread(&bh, journal, next_log_block);
+ if (err)
+ goto failed;
+
+ next_log_block++;
+ wrap(journal, next_log_block);
+
+ /* What kind of buffer is it?
+ *
+ * If it is a descriptor block, check that it has the
+ * expected sequence number. Otherwise, we're all done
+ * here. */
+
+ tmp = (journal_header_t *)bh->b_data;
+
+ if (tmp->h_magic != cpu_to_be32(JFS_MAGIC_NUMBER)) {
+ brelse(bh);
+ break;
+ }
+
+ blocktype = be32_to_cpu(tmp->h_blocktype);
+ sequence = be32_to_cpu(tmp->h_sequence);
+ jbd_debug(3, "Found magic %d, sequence %d\n",
+ blocktype, sequence);
+
+ if (sequence != next_commit_ID) {
+ brelse(bh);
+ break;
+ }
+
+ /* OK, we have a valid descriptor block which matches
+ * all of the sequence number checks. What are we going
+ * to do with it? That depends on the pass... */
+
+ switch(blocktype) {
+ case JFS_DESCRIPTOR_BLOCK:
+ /* If it is a valid descriptor block, replay it
+ * in pass REPLAY; otherwise, just skip over the
+ * blocks it describes. */
+ if (pass != PASS_REPLAY) {
+ next_log_block +=
+ count_tags(bh, journal->j_blocksize);
+ wrap(journal, next_log_block);
+ brelse(bh);
+ continue;
+ }
+
+ /* A descriptor block: we can now write all of
+ * the data blocks. Yay, useful work is finally
+ * getting done here! */
+
+ tagp = &bh->b_data[sizeof(journal_header_t)];
+ while ((tagp - bh->b_data +sizeof(journal_block_tag_t))
+ <= journal->j_blocksize) {
+ unsigned long io_block;
+
+ tag = (journal_block_tag_t *) tagp;
+ flags = be32_to_cpu(tag->t_flags);
+
+ io_block = next_log_block++;
+ wrap(journal, next_log_block);
+ err = jread(&obh, journal, io_block);
+ if (err) {
+ /* Recover what we can, but
+ * report failure at the end. */
+ success = err;
+ printk (KERN_ERR
+ "JBD: IO error %d recovering "
+ "block %ld in log\n",
+ err, io_block);
+ } else {
+ unsigned long blocknr;
+
+ J_ASSERT(obh != NULL);
+ blocknr = be32_to_cpu(tag->t_blocknr);
+
+ /* If the block has been
+ * revoked, then we're all done
+ * here. */
+ if (journal_test_revoke
+ (journal, blocknr,
+ next_commit_ID)) {
+ brelse(obh);
+ ++info->nr_revoke_hits;
+ goto skip_write;
+ }
+
+ /* Find a buffer for the new
+ * data being restored */
+ nbh = __getblk(journal->j_fs_dev,
+ blocknr,
+ journal->j_blocksize);
+ if (nbh == NULL) {
+ printk(KERN_ERR
+ "JBD: Out of memory "
+ "during recovery.\n");
+ err = -ENOMEM;
+ brelse(bh);
+ brelse(obh);
+ goto failed;
+ }
+
+ lock_buffer(nbh);
+ memcpy(nbh->b_data, obh->b_data,
+ journal->j_blocksize);
+ if (flags & JFS_FLAG_ESCAPE) {
+ *((__be32 *)bh->b_data) =
+ cpu_to_be32(JFS_MAGIC_NUMBER);
+ }
+
+ BUFFER_TRACE(nbh, "marking dirty");
+ set_buffer_uptodate(nbh);
+ mark_buffer_dirty(nbh);
+ BUFFER_TRACE(nbh, "marking uptodate");
+ ++info->nr_replays;
+ /* ll_rw_block(WRITE, 1, &nbh); */
+ unlock_buffer(nbh);
+ brelse(obh);
+ brelse(nbh);
+ }
+
+ skip_write:
+ tagp += sizeof(journal_block_tag_t);
+ if (!(flags & JFS_FLAG_SAME_UUID))
+ tagp += 16;
+
+ if (flags & JFS_FLAG_LAST_TAG)
+ break;
+ }
+
+ brelse(bh);
+ continue;
+
+ case JFS_COMMIT_BLOCK:
+ /* Found an expected commit block: not much to
+ * do other than move on to the next sequence
+ * number. */
+ brelse(bh);
+ next_commit_ID++;
+ continue;
+
+ case JFS_REVOKE_BLOCK:
+ /* If we aren't in the REVOKE pass, then we can
+ * just skip over this block. */
+ if (pass != PASS_REVOKE) {
+ brelse(bh);
+ continue;
+ }
+
+ err = scan_revoke_records(journal, bh,
+ next_commit_ID, info);
+ brelse(bh);
+ if (err)
+ goto failed;
+ continue;
+
+ default:
+ jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
+ blocktype);
+ brelse(bh);
+ goto done;
+ }
+ }
+
+ done:
+ /*
+ * We broke out of the log scan loop: either we came to the
+ * known end of the log or we found an unexpected block in the
+ * log. If the latter happened, then we know that the "current"
+ * transaction marks the end of the valid log.
+ */
+
+ if (pass == PASS_SCAN)
+ info->end_transaction = next_commit_ID;
+ else {
+ /* It's really bad news if different passes end up at
+ * different places (but possible due to IO errors). */
+ if (info->end_transaction != next_commit_ID) {
+ printk (KERN_ERR "JBD: recovery pass %d ended at "
+ "transaction %u, expected %u\n",
+ pass, next_commit_ID, info->end_transaction);
+ if (!success)
+ success = -EIO;
+ }
+ }
+
+ return success;
+
+ failed:
+ return err;
+}
+
+
+/* Scan a revoke record, marking all blocks mentioned as revoked. */
+
+static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
+ tid_t sequence, struct recovery_info *info)
+{
+ journal_revoke_header_t *header;
+ int offset, max;
+
+ header = (journal_revoke_header_t *) bh->b_data;
+ offset = sizeof(journal_revoke_header_t);
+ max = be32_to_cpu(header->r_count);
+
+ while (offset < max) {
+ unsigned long blocknr;
+ int err;
+
+ blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
+ offset += 4;
+ err = journal_set_revoke(journal, blocknr, sequence);
+ if (err)
+ return err;
+ ++info->nr_revokes;
+ }
+ return 0;
+}
diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c
new file mode 100644
index 00000000000..c532429d8d9
--- /dev/null
+++ b/fs/jbd2/revoke.c
@@ -0,0 +1,703 @@
+/*
+ * linux/fs/revoke.c
+ *
+ * Written by Stephen C. Tweedie <sct@redhat.com>, 2000
+ *
+ * Copyright 2000 Red Hat corp --- All Rights Reserved
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * Journal revoke routines for the generic filesystem journaling code;
+ * part of the ext2fs journaling system.
+ *
+ * Revoke is the mechanism used to prevent old log records for deleted
+ * metadata from being replayed on top of newer data using the same
+ * blocks. The revoke mechanism is used in two separate places:
+ *
+ * + Commit: during commit we write the entire list of the current
+ * transaction's revoked blocks to the journal
+ *
+ * + Recovery: during recovery we record the transaction ID of all
+ * revoked blocks. If there are multiple revoke records in the log
+ * for a single block, only the last one counts, and if there is a log
+ * entry for a block beyond the last revoke, then that log entry still
+ * gets replayed.
+ *
+ * We can get interactions between revokes and new log data within a
+ * single transaction:
+ *
+ * Block is revoked and then journaled:
+ * The desired end result is the journaling of the new block, so we
+ * cancel the revoke before the transaction commits.
+ *
+ * Block is journaled and then revoked:
+ * The revoke must take precedence over the write of the block, so we
+ * need either to cancel the journal entry or to write the revoke
+ * later in the log than the log block. In this case, we choose the
+ * latter: journaling a block cancels any revoke record for that block
+ * in the current transaction, so any revoke for that block in the
+ * transaction must have happened after the block was journaled and so
+ * the revoke must take precedence.
+ *
+ * Block is revoked and then written as data:
+ * The data write is allowed to succeed, but the revoke is _not_
+ * cancelled. We still need to prevent old log records from
+ * overwriting the new data. We don't even need to clear the revoke
+ * bit here.
+ *
+ * Revoke information on buffers is a tri-state value:
+ *
+ * RevokeValid clear: no cached revoke status, need to look it up
+ * RevokeValid set, Revoked clear:
+ * buffer has not been revoked, and cancel_revoke
+ * need do nothing.
+ * RevokeValid set, Revoked set:
+ * buffer has been revoked.
+ */
+
+#ifndef __KERNEL__
+#include "jfs_user.h"
+#else
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/jbd.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/smp_lock.h>
+#include <linux/init.h>
+#endif
+
+static kmem_cache_t *revoke_record_cache;
+static kmem_cache_t *revoke_table_cache;
+
+/* Each revoke record represents one single revoked block. During
+ journal replay, this involves recording the transaction ID of the
+ last transaction to revoke this block. */
+
+struct jbd_revoke_record_s
+{
+ struct list_head hash;
+ tid_t sequence; /* Used for recovery only */
+ unsigned long blocknr;
+};
+
+
+/* The revoke table is just a simple hash table of revoke records. */
+struct jbd_revoke_table_s
+{
+ /* It is conceivable that we might want a larger hash table
+ * for recovery. Must be a power of two. */
+ int hash_size;
+ int hash_shift;
+ struct list_head *hash_table;
+};
+
+
+#ifdef __KERNEL__
+static void write_one_revoke_record(journal_t *, transaction_t *,
+ struct journal_head **, int *,
+ struct jbd_revoke_record_s *);
+static void flush_descriptor(journal_t *, struct journal_head *, int);
+#endif
+
+/* Utility functions to maintain the revoke table */
+
+/* Borrowed from buffer.c: this is a tried and tested block hash function */
+static inline int hash(journal_t *journal, unsigned long block)
+{
+ struct jbd_revoke_table_s *table = journal->j_revoke;
+ int hash_shift = table->hash_shift;
+
+ return ((block << (hash_shift - 6)) ^
+ (block >> 13) ^
+ (block << (hash_shift - 12))) & (table->hash_size - 1);
+}
+
+static int insert_revoke_hash(journal_t *journal, unsigned long blocknr,
+ tid_t seq)
+{
+ struct list_head *hash_list;
+ struct jbd_revoke_record_s *record;
+
+repeat:
+ record = kmem_cache_alloc(revoke_record_cache, GFP_NOFS);
+ if (!record)
+ goto oom;
+
+ record->sequence = seq;
+ record->blocknr = blocknr;
+ hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
+ spin_lock(&journal->j_revoke_lock);
+ list_add(&record->hash, hash_list);
+ spin_unlock(&journal->j_revoke_lock);
+ return 0;
+
+oom:
+ if (!journal_oom_retry)
+ return -ENOMEM;
+ jbd_debug(1, "ENOMEM in %s, retrying\n", __FUNCTION__);
+ yield();
+ goto repeat;
+}
+
+/* Find a revoke record in the journal's hash table. */
+
+static struct jbd_revoke_record_s *find_revoke_record(journal_t *journal,
+ unsigned long blocknr)
+{
+ struct list_head *hash_list;
+ struct jbd_revoke_record_s *record;
+
+ hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
+
+ spin_lock(&journal->j_revoke_lock);
+ record = (struct jbd_revoke_record_s *) hash_list->next;
+ while (&(record->hash) != hash_list) {
+ if (record->blocknr == blocknr) {
+ spin_unlock(&journal->j_revoke_lock);
+ return record;
+ }
+ record = (struct jbd_revoke_record_s *) record->hash.next;
+ }
+ spin_unlock(&journal->j_revoke_lock);
+ return NULL;
+}
+
+int __init journal_init_revoke_caches(void)
+{
+ revoke_record_cache = kmem_cache_create("revoke_record",
+ sizeof(struct jbd_revoke_record_s),
+ 0, SLAB_HWCACHE_ALIGN, NULL, NULL);
+ if (revoke_record_cache == 0)
+ return -ENOMEM;
+
+ revoke_table_cache = kmem_cache_create("revoke_table",
+ sizeof(struct jbd_revoke_table_s),
+ 0, 0, NULL, NULL);
+ if (revoke_table_cache == 0) {
+ kmem_cache_destroy(revoke_record_cache);
+ revoke_record_cache = NULL;
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+void journal_destroy_revoke_caches(void)
+{
+ kmem_cache_destroy(revoke_record_cache);
+ revoke_record_cache = NULL;
+ kmem_cache_destroy(revoke_table_cache);
+ revoke_table_cache = NULL;
+}
+
+/* Initialise the revoke table for a given journal to a given size. */
+
+int journal_init_revoke(journal_t *journal, int hash_size)
+{
+ int shift, tmp;
+
+ J_ASSERT (journal->j_revoke_table[0] == NULL);
+
+ shift = 0;
+ tmp = hash_size;
+ while((tmp >>= 1UL) != 0UL)
+ shift++;
+
+ journal->j_revoke_table[0] = kmem_cache_alloc(revoke_table_cache, GFP_KERNEL);
+ if (!journal->j_revoke_table[0])
+ return -ENOMEM;
+ journal->j_revoke = journal->j_revoke_table[0];
+
+ /* Check that the hash_size is a power of two */
+ J_ASSERT ((hash_size & (hash_size-1)) == 0);
+
+ journal->j_revoke->hash_size = hash_size;
+
+ journal->j_revoke->hash_shift = shift;
+
+ journal->j_revoke->hash_table =
+ kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
+ if (!journal->j_revoke->hash_table) {
+ kmem_cache_free(revoke_table_cache, journal->j_revoke_table[0]);
+ journal->j_revoke = NULL;
+ return -ENOMEM;
+ }
+
+ for (tmp = 0; tmp < hash_size; tmp++)
+ INIT_LIST_HEAD(&journal->j_revoke->hash_table[tmp]);
+
+ journal->j_revoke_table[1] = kmem_cache_alloc(revoke_table_cache, GFP_KERNEL);
+ if (!journal->j_revoke_table[1]) {
+ kfree(journal->j_revoke_table[0]->hash_table);
+ kmem_cache_free(revoke_table_cache, journal->j_revoke_table[0]);
+ return -ENOMEM;
+ }
+
+ journal->j_revoke = journal->j_revoke_table[1];
+
+ /* Check that the hash_size is a power of two */
+ J_ASSERT ((hash_size & (hash_size-1)) == 0);
+
+ journal->j_revoke->hash_size = hash_size;
+
+ journal->j_revoke->hash_shift = shift;
+
+ journal->j_revoke->hash_table =
+ kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
+ if (!journal->j_revoke->hash_table) {
+ kfree(journal->j_revoke_table[0]->hash_table);
+ kmem_cache_free(revoke_table_cache, journal->j_revoke_table[0]);
+ kmem_cache_free(revoke_table_cache, journal->j_revoke_table[1]);
+ journal->j_revoke = NULL;
+ return -ENOMEM;
+ }
+
+ for (tmp = 0; tmp < hash_size; tmp++)
+ INIT_LIST_HEAD(&journal->j_revoke->hash_table[tmp]);
+
+ spin_lock_init(&journal->j_revoke_lock);
+
+ return 0;
+}
+
+/* Destoy a journal's revoke table. The table must already be empty! */
+
+void journal_destroy_revoke(journal_t *journal)
+{
+ struct jbd_revoke_table_s *table;
+ struct list_head *hash_list;
+ int i;
+
+ table = journal->j_revoke_table[0];
+ if (!table)
+ return;
+
+ for (i=0; i<table->hash_size; i++) {
+ hash_list = &table->hash_table[i];
+ J_ASSERT (list_empty(hash_list));
+ }
+
+ kfree(table->hash_table);
+ kmem_cache_free(revoke_table_cache, table);
+ journal->j_revoke = NULL;
+
+ table = journal->j_revoke_table[1];
+ if (!table)
+ return;
+
+ for (i=0; i<table->hash_size; i++) {
+ hash_list = &table->hash_table[i];
+ J_ASSERT (list_empty(hash_list));
+ }
+
+ kfree(table->hash_table);
+ kmem_cache_free(revoke_table_cache, table);
+ journal->j_revoke = NULL;
+}
+
+
+#ifdef __KERNEL__
+
+/*
+ * journal_revoke: revoke a given buffer_head from the journal. This
+ * prevents the block from being replayed during recovery if we take a
+ * crash after this current transaction commits. Any subsequent
+ * metadata writes of the buffer in this transaction cancel the
+ * revoke.
+ *
+ * Note that this call may block --- it is up to the caller to make
+ * sure that there are no further calls to journal_write_metadata
+ * before the revoke is complete. In ext3, this implies calling the
+ * revoke before clearing the block bitmap when we are deleting
+ * metadata.
+ *
+ * Revoke performs a journal_forget on any buffer_head passed in as a
+ * parameter, but does _not_ forget the buffer_head if the bh was only
+ * found implicitly.
+ *
+ * bh_in may not be a journalled buffer - it may have come off
+ * the hash tables without an attached journal_head.
+ *
+ * If bh_in is non-zero, journal_revoke() will decrement its b_count
+ * by one.
+ */
+
+int journal_revoke(handle_t *handle, unsigned long blocknr,
+ struct buffer_head *bh_in)
+{
+ struct buffer_head *bh = NULL;
+ journal_t *journal;
+ struct block_device *bdev;
+ int err;
+
+ might_sleep();
+ if (bh_in)
+ BUFFER_TRACE(bh_in, "enter");
+
+ journal = handle->h_transaction->t_journal;
+ if (!journal_set_features(journal, 0, 0, JFS_FEATURE_INCOMPAT_REVOKE)){
+ J_ASSERT (!"Cannot set revoke feature!");
+ return -EINVAL;
+ }
+
+ bdev = journal->j_fs_dev;
+ bh = bh_in;
+
+ if (!bh) {
+ bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
+ if (bh)
+ BUFFER_TRACE(bh, "found on hash");
+ }
+#ifdef JBD_EXPENSIVE_CHECKING
+ else {
+ struct buffer_head *bh2;
+
+ /* If there is a different buffer_head lying around in
+ * memory anywhere... */
+ bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize);
+ if (bh2) {
+ /* ... and it has RevokeValid status... */
+ if (bh2 != bh && buffer_revokevalid(bh2))
+ /* ...then it better be revoked too,
+ * since it's illegal to create a revoke
+ * record against a buffer_head which is
+ * not marked revoked --- that would
+ * risk missing a subsequent revoke
+ * cancel. */
+ J_ASSERT_BH(bh2, buffer_revoked(bh2));
+ put_bh(bh2);
+ }
+ }
+#endif
+
+ /* We really ought not ever to revoke twice in a row without
+ first having the revoke cancelled: it's illegal to free a
+ block twice without allocating it in between! */
+ if (bh) {
+ if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
+ "inconsistent data on disk")) {
+ if (!bh_in)
+ brelse(bh);
+ return -EIO;
+ }
+ set_buffer_revoked(bh);
+ set_buffer_revokevalid(bh);
+ if (bh_in) {
+ BUFFER_TRACE(bh_in, "call journal_forget");
+ journal_forget(handle, bh_in);
+ } else {
+ BUFFER_TRACE(bh, "call brelse");
+ __brelse(bh);
+ }
+ }
+
+ jbd_debug(2, "insert revoke for block %lu, bh_in=%p\n", blocknr, bh_in);
+ err = insert_revoke_hash(journal, blocknr,
+ handle->h_transaction->t_tid);
+ BUFFER_TRACE(bh_in, "exit");
+ return err;
+}
+
+/*
+ * Cancel an outstanding revoke. For use only internally by the
+ * journaling code (called from journal_get_write_access).
+ *
+ * We trust buffer_revoked() on the buffer if the buffer is already
+ * being journaled: if there is no revoke pending on the buffer, then we
+ * don't do anything here.
+ *
+ * This would break if it were possible for a buffer to be revoked and
+ * discarded, and then reallocated within the same transaction. In such
+ * a case we would have lost the revoked bit, but when we arrived here
+ * the second time we would still have a pending revoke to cancel. So,
+ * do not trust the Revoked bit on buffers unless RevokeValid is also
+ * set.
+ *
+ * The caller must have the journal locked.
+ */
+int journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
+{
+ struct jbd_revoke_record_s *record;
+ journal_t *journal = handle->h_transaction->t_journal;
+ int need_cancel;
+ int did_revoke = 0; /* akpm: debug */
+ struct buffer_head *bh = jh2bh(jh);
+
+ jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
+
+ /* Is the existing Revoke bit valid? If so, we trust it, and
+ * only perform the full cancel if the revoke bit is set. If
+ * not, we can't trust the revoke bit, and we need to do the
+ * full search for a revoke record. */
+ if (test_set_buffer_revokevalid(bh)) {
+ need_cancel = test_clear_buffer_revoked(bh);
+ } else {
+ need_cancel = 1;
+ clear_buffer_revoked(bh);
+ }
+
+ if (need_cancel) {
+ record = find_revoke_record(journal, bh->b_blocknr);
+ if (record) {
+ jbd_debug(4, "cancelled existing revoke on "
+ "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
+ spin_lock(&journal->j_revoke_lock);
+ list_del(&record->hash);
+ spin_unlock(&journal->j_revoke_lock);
+ kmem_cache_free(revoke_record_cache, record);
+ did_revoke = 1;
+ }
+ }
+
+#ifdef JBD_EXPENSIVE_CHECKING
+ /* There better not be one left behind by now! */
+ record = find_revoke_record(journal, bh->b_blocknr);
+ J_ASSERT_JH(jh, record == NULL);
+#endif
+
+ /* Finally, have we just cleared revoke on an unhashed
+ * buffer_head? If so, we'd better make sure we clear the
+ * revoked status on any hashed alias too, otherwise the revoke
+ * state machine will get very upset later on. */
+ if (need_cancel) {
+ struct buffer_head *bh2;
+ bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
+ if (bh2) {
+ if (bh2 != bh)
+ clear_buffer_revoked(bh2);
+ __brelse(bh2);
+ }
+ }
+ return did_revoke;
+}
+
+/* journal_switch_revoke table select j_revoke for next transaction
+ * we do not want to suspend any processing until all revokes are
+ * written -bzzz
+ */
+void journal_switch_revoke_table(journal_t *journal)
+{
+ int i;
+
+ if (journal->j_revoke == journal->j_revoke_table[0])
+ journal->j_revoke = journal->j_revoke_table[1];
+ else
+ journal->j_revoke = journal->j_revoke_table[0];
+
+ for (i = 0; i < journal->j_revoke->hash_size; i++)
+ INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
+}
+
+/*
+ * Write revoke records to the journal for all entries in the current
+ * revoke hash, deleting the entries as we go.
+ *
+ * Called with the journal lock held.
+ */
+
+void journal_write_revoke_records(journal_t *journal,
+ transaction_t *transaction)
+{
+ struct journal_head *descriptor;
+ struct jbd_revoke_record_s *record;
+ struct jbd_revoke_table_s *revoke;
+ struct list_head *hash_list;
+ int i, offset, count;
+
+ descriptor = NULL;
+ offset = 0;
+ count = 0;
+
+ /* select revoke table for committing transaction */
+ revoke = journal->j_revoke == journal->j_revoke_table[0] ?
+ journal->j_revoke_table[1] : journal->j_revoke_table[0];
+
+ for (i = 0; i < revoke->hash_size; i++) {
+ hash_list = &revoke->hash_table[i];
+
+ while (!list_empty(hash_list)) {
+ record = (struct jbd_revoke_record_s *)
+ hash_list->next;
+ write_one_revoke_record(journal, transaction,
+ &descriptor, &offset,
+ record);
+ count++;
+ list_del(&record->hash);
+ kmem_cache_free(revoke_record_cache, record);
+ }
+ }
+ if (descriptor)
+ flush_descriptor(journal, descriptor, offset);
+ jbd_debug(1, "Wrote %d revoke records\n", count);
+}
+
+/*
+ * Write out one revoke record. We need to create a new descriptor
+ * block if the old one is full or if we have not already created one.
+ */
+
+static void write_one_revoke_record(journal_t *journal,
+ transaction_t *transaction,
+ struct journal_head **descriptorp,
+ int *offsetp,
+ struct jbd_revoke_record_s *record)
+{
+ struct journal_head *descriptor;
+ int offset;
+ journal_header_t *header;
+
+ /* If we are already aborting, this all becomes a noop. We
+ still need to go round the loop in
+ journal_write_revoke_records in order to free all of the
+ revoke records: only the IO to the journal is omitted. */
+ if (is_journal_aborted(journal))
+ return;
+
+ descriptor = *descriptorp;
+ offset = *offsetp;
+
+ /* Make sure we have a descriptor with space left for the record */
+ if (descriptor) {
+ if (offset == journal->j_blocksize) {
+ flush_descriptor(journal, descriptor, offset);
+ descriptor = NULL;
+ }
+ }
+
+ if (!descriptor) {
+ descriptor = journal_get_descriptor_buffer(journal);
+ if (!descriptor)
+ return;
+ header = (journal_header_t *) &jh2bh(descriptor)->b_data[0];
+ header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
+ header->h_blocktype = cpu_to_be32(JFS_REVOKE_BLOCK);
+ header->h_sequence = cpu_to_be32(transaction->t_tid);
+
+ /* Record it so that we can wait for IO completion later */
+ JBUFFER_TRACE(descriptor, "file as BJ_LogCtl");
+ journal_file_buffer(descriptor, transaction, BJ_LogCtl);
+
+ offset = sizeof(journal_revoke_header_t);
+ *descriptorp = descriptor;
+ }
+
+ * ((__be32 *)(&jh2bh(descriptor)->b_data[offset])) =
+ cpu_to_be32(record->blocknr);
+ offset += 4;
+ *offsetp = offset;
+}
+
+/*
+ * Flush a revoke descriptor out to the journal. If we are aborting,
+ * this is a noop; otherwise we are generating a buffer which needs to
+ * be waited for during commit, so it has to go onto the appropriate
+ * journal buffer list.
+ */
+
+static void flush_descriptor(journal_t *journal,
+ struct journal_head *descriptor,
+ int offset)
+{
+ journal_revoke_header_t *header;
+ struct buffer_head *bh = jh2bh(descriptor);
+
+ if (is_journal_aborted(journal)) {
+ put_bh(bh);
+ return;
+ }
+
+ header = (journal_revoke_header_t *) jh2bh(descriptor)->b_data;
+ header->r_count = cpu_to_be32(offset);
+ set_buffer_jwrite(bh);
+ BUFFER_TRACE(bh, "write");
+ set_buffer_dirty(bh);
+ ll_rw_block(SWRITE, 1, &bh);
+}
+#endif
+
+/*
+ * Revoke support for recovery.
+ *
+ * Recovery needs to be able to:
+ *
+ * record all revoke records, including the tid of the latest instance
+ * of each revoke in the journal
+ *
+ * check whether a given block in a given transaction should be replayed
+ * (ie. has not been revoked by a revoke record in that or a subsequent
+ * transaction)
+ *
+ * empty the revoke table after recovery.
+ */
+
+/*
+ * First, setting revoke records. We create a new revoke record for
+ * every block ever revoked in the log as we scan it for recovery, and
+ * we update the existing records if we find multiple revokes for a
+ * single block.
+ */
+
+int journal_set_revoke(journal_t *journal,
+ unsigned long blocknr,
+ tid_t sequence)
+{
+ struct jbd_revoke_record_s *record;
+
+ record = find_revoke_record(journal, blocknr);
+ if (record) {
+ /* If we have multiple occurrences, only record the
+ * latest sequence number in the hashed record */
+ if (tid_gt(sequence, record->sequence))
+ record->sequence = sequence;
+ return 0;
+ }
+ return insert_revoke_hash(journal, blocknr, sequence);
+}
+
+/*
+ * Test revoke records. For a given block referenced in the log, has
+ * that block been revoked? A revoke record with a given transaction
+ * sequence number revokes all blocks in that transaction and earlier
+ * ones, but later transactions still need replayed.
+ */
+
+int journal_test_revoke(journal_t *journal,
+ unsigned long blocknr,
+ tid_t sequence)
+{
+ struct jbd_revoke_record_s *record;
+
+ record = find_revoke_record(journal, blocknr);
+ if (!record)
+ return 0;
+ if (tid_gt(sequence, record->sequence))
+ return 0;
+ return 1;
+}
+
+/*
+ * Finally, once recovery is over, we need to clear the revoke table so
+ * that it can be reused by the running filesystem.
+ */
+
+void journal_clear_revoke(journal_t *journal)
+{
+ int i;
+ struct list_head *hash_list;
+ struct jbd_revoke_record_s *record;
+ struct jbd_revoke_table_s *revoke;
+
+ revoke = journal->j_revoke;
+
+ for (i = 0; i < revoke->hash_size; i++) {
+ hash_list = &revoke->hash_table[i];
+ while (!list_empty(hash_list)) {
+ record = (struct jbd_revoke_record_s*) hash_list->next;
+ list_del(&record->hash);
+ kmem_cache_free(revoke_record_cache, record);
+ }
+ }
+}
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
new file mode 100644
index 00000000000..e1b3c8af4d1
--- /dev/null
+++ b/fs/jbd2/transaction.c
@@ -0,0 +1,2080 @@
+/*
+ * linux/fs/transaction.c
+ *
+ * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
+ *
+ * Copyright 1998 Red Hat corp --- All Rights Reserved
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * Generic filesystem transaction handling code; part of the ext2fs
+ * journaling system.
+ *
+ * This file manages transactions (compound commits managed by the
+ * journaling code) and handles (individual atomic operations by the
+ * filesystem).
+ */
+
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/jbd.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/timer.h>
+#include <linux/smp_lock.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+
+/*
+ * get_transaction: obtain a new transaction_t object.
+ *
+ * Simply allocate and initialise a new transaction. Create it in
+ * RUNNING state and add it to the current journal (which should not
+ * have an existing running transaction: we only make a new transaction
+ * once we have started to commit the old one).
+ *
+ * Preconditions:
+ * The journal MUST be locked. We don't perform atomic mallocs on the
+ * new transaction and we can't block without protecting against other
+ * processes trying to touch the journal while it is in transition.
+ *
+ * Called under j_state_lock
+ */
+
+static transaction_t *
+get_transaction(journal_t *journal, transaction_t *transaction)
+{
+ transaction->t_journal = journal;
+ transaction->t_state = T_RUNNING;
+ transaction->t_tid = journal->j_transaction_sequence++;
+ transaction->t_expires = jiffies + journal->j_commit_interval;
+ spin_lock_init(&transaction->t_handle_lock);
+
+ /* Set up the commit timer for the new transaction. */
+ journal->j_commit_timer.expires = transaction->t_expires;
+ add_timer(&journal->j_commit_timer);
+
+ J_ASSERT(journal->j_running_transaction == NULL);
+ journal->j_running_transaction = transaction;
+
+ return transaction;
+}
+
+/*
+ * Handle management.
+ *
+ * A handle_t is an object which represents a single atomic update to a
+ * filesystem, and which tracks all of the modifications which form part
+ * of that one update.
+ */
+
+/*
+ * start_this_handle: Given a handle, deal with any locking or stalling
+ * needed to make sure that there is enough journal space for the handle
+ * to begin. Attach the handle to a transaction and set up the
+ * transaction's buffer credits.
+ */
+
+static int start_this_handle(journal_t *journal, handle_t *handle)
+{
+ transaction_t *transaction;
+ int needed;
+ int nblocks = handle->h_buffer_credits;
+ transaction_t *new_transaction = NULL;
+ int ret = 0;
+
+ if (nblocks > journal->j_max_transaction_buffers) {
+ printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
+ current->comm, nblocks,
+ journal->j_max_transaction_buffers);
+ ret = -ENOSPC;
+ goto out;
+ }
+
+alloc_transaction:
+ if (!journal->j_running_transaction) {
+ new_transaction = jbd_kmalloc(sizeof(*new_transaction),
+ GFP_NOFS);
+ if (!new_transaction) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ memset(new_transaction, 0, sizeof(*new_transaction));
+ }
+
+ jbd_debug(3, "New handle %p going live.\n", handle);
+
+repeat:
+
+ /*
+ * We need to hold j_state_lock until t_updates has been incremented,
+ * for proper journal barrier handling
+ */
+ spin_lock(&journal->j_state_lock);
+repeat_locked:
+ if (is_journal_aborted(journal) ||
+ (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) {
+ spin_unlock(&journal->j_state_lock);
+ ret = -EROFS;
+ goto out;
+ }
+
+ /* Wait on the journal's transaction barrier if necessary */
+ if (journal->j_barrier_count) {
+ spin_unlock(&journal->j_state_lock);
+ wait_event(journal->j_wait_transaction_locked,
+ journal->j_barrier_count == 0);
+ goto repeat;
+ }
+
+ if (!journal->j_running_transaction) {
+ if (!new_transaction) {
+ spin_unlock(&journal->j_state_lock);
+ goto alloc_transaction;
+ }
+ get_transaction(journal, new_transaction);
+ new_transaction = NULL;
+ }
+
+ transaction = journal->j_running_transaction;
+
+ /*
+ * If the current transaction is locked down for commit, wait for the
+ * lock to be released.
+ */
+ if (transaction->t_state == T_LOCKED) {
+ DEFINE_WAIT(wait);
+
+ prepare_to_wait(&journal->j_wait_transaction_locked,
+ &wait, TASK_UNINTERRUPTIBLE);
+ spin_unlock(&journal->j_state_lock);
+ schedule();
+ finish_wait(&journal->j_wait_transaction_locked, &wait);
+ goto repeat;
+ }
+
+ /*
+ * If there is not enough space left in the log to write all potential
+ * buffers requested by this operation, we need to stall pending a log
+ * checkpoint to free some more log space.
+ */
+ spin_lock(&transaction->t_handle_lock);
+ needed = transaction->t_outstanding_credits + nblocks;
+
+ if (needed > journal->j_max_transaction_buffers) {
+ /*
+ * If the current transaction is already too large, then start
+ * to commit it: we can then go back and attach this handle to
+ * a new transaction.
+ */
+ DEFINE_WAIT(wait);
+
+ jbd_debug(2, "Handle %p starting new commit...\n", handle);
+ spin_unlock(&transaction->t_handle_lock);
+ prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
+ TASK_UNINTERRUPTIBLE);
+ __log_start_commit(journal, transaction->t_tid);
+ spin_unlock(&journal->j_state_lock);
+ schedule();
+ finish_wait(&journal->j_wait_transaction_locked, &wait);
+ goto repeat;
+ }
+
+ /*
+ * The commit code assumes that it can get enough log space
+ * without forcing a checkpoint. This is *critical* for
+ * correctness: a checkpoint of a buffer which is also
+ * associated with a committing transaction creates a deadlock,
+ * so commit simply cannot force through checkpoints.
+ *
+ * We must therefore ensure the necessary space in the journal
+ * *before* starting to dirty potentially checkpointed buffers
+ * in the new transaction.
+ *
+ * The worst part is, any transaction currently committing can
+ * reduce the free space arbitrarily. Be careful to account for
+ * those buffers when checkpointing.
+ */
+
+ /*
+ * @@@ AKPM: This seems rather over-defensive. We're giving commit
+ * a _lot_ of headroom: 1/4 of the journal plus the size of
+ * the committing transaction. Really, we only need to give it
+ * committing_transaction->t_outstanding_credits plus "enough" for
+ * the log control blocks.
+ * Also, this test is inconsitent with the matching one in
+ * journal_extend().
+ */
+ if (__log_space_left(journal) < jbd_space_needed(journal)) {
+ jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
+ spin_unlock(&transaction->t_handle_lock);
+ __log_wait_for_space(journal);
+ goto repeat_locked;
+ }
+
+ /* OK, account for the buffers that this operation expects to
+ * use and add the handle to the running transaction. */
+
+ handle->h_transaction = transaction;
+ transaction->t_outstanding_credits += nblocks;
+ transaction->t_updates++;
+ transaction->t_handle_count++;
+ jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
+ handle, nblocks, transaction->t_outstanding_credits,
+ __log_space_left(journal));
+ spin_unlock(&transaction->t_handle_lock);
+ spin_unlock(&journal->j_state_lock);
+out:
+ if (unlikely(new_transaction)) /* It's usually NULL */
+ kfree(new_transaction);
+ return ret;
+}
+
+/* Allocate a new handle. This should probably be in a slab... */
+static handle_t *new_handle(int nblocks)
+{
+ handle_t *handle = jbd_alloc_handle(GFP_NOFS);
+ if (!handle)
+ return NULL;
+ memset(handle, 0, sizeof(*handle));
+ handle->h_buffer_credits = nblocks;
+ handle->h_ref = 1;
+
+ return handle;
+}
+
+/**
+ * handle_t *journal_start() - Obtain a new handle.
+ * @journal: Journal to start transaction on.
+ * @nblocks: number of block buffer we might modify
+ *
+ * We make sure that the transaction can guarantee at least nblocks of
+ * modified buffers in the log. We block until the log can guarantee
+ * that much space.
+ *
+ * This function is visible to journal users (like ext3fs), so is not
+ * called with the journal already locked.
+ *
+ * Return a pointer to a newly allocated handle, or NULL on failure
+ */
+handle_t *journal_start(journal_t *journal, int nblocks)
+{
+ handle_t *handle = journal_current_handle();
+ int err;
+
+ if (!journal)
+ return ERR_PTR(-EROFS);
+
+ if (handle) {
+ J_ASSERT(handle->h_transaction->t_journal == journal);
+ handle->h_ref++;
+ return handle;
+ }
+
+ handle = new_handle(nblocks);
+ if (!handle)
+ return ERR_PTR(-ENOMEM);
+
+ current->journal_info = handle;
+
+ err = start_this_handle(journal, handle);
+ if (err < 0) {
+ jbd_free_handle(handle);
+ current->journal_info = NULL;
+ handle = ERR_PTR(err);
+ }
+ return handle;
+}
+
+/**
+ * int journal_extend() - extend buffer credits.
+ * @handle: handle to 'extend'
+ * @nblocks: nr blocks to try to extend by.
+ *
+ * Some transactions, such as large extends and truncates, can be done
+ * atomically all at once or in several stages. The operation requests
+ * a credit for a number of buffer modications in advance, but can
+ * extend its credit if it needs more.
+ *
+ * journal_extend tries to give the running handle more buffer credits.
+ * It does not guarantee that allocation - this is a best-effort only.
+ * The calling process MUST be able to deal cleanly with a failure to
+ * extend here.
+ *
+ * Return 0 on success, non-zero on failure.
+ *
+ * return code < 0 implies an error
+ * return code > 0 implies normal transaction-full status.
+ */
+int journal_extend(handle_t *handle, int nblocks)
+{
+ transaction_t *transaction = handle->h_transaction;
+ journal_t *journal = transaction->t_journal;
+ int result;
+ int wanted;
+
+ result = -EIO;
+ if (is_handle_aborted(handle))
+ goto out;
+
+ result = 1;
+
+ spin_lock(&journal->j_state_lock);
+
+ /* Don't extend a locked-down transaction! */
+ if (handle->h_transaction->t_state != T_RUNNING) {
+ jbd_debug(3, "denied handle %p %d blocks: "
+ "transaction not running\n", handle, nblocks);
+ goto error_out;
+ }
+
+ spin_lock(&transaction->t_handle_lock);
+ wanted = transaction->t_outstanding_credits + nblocks;
+
+ if (wanted > journal->j_max_transaction_buffers) {
+ jbd_debug(3, "denied handle %p %d blocks: "
+ "transaction too large\n", handle, nblocks);
+ goto unlock;
+ }
+
+ if (wanted > __log_space_left(journal)) {
+ jbd_debug(3, "denied handle %p %d blocks: "
+ "insufficient log space\n", handle, nblocks);
+ goto unlock;
+ }
+
+ handle->h_buffer_credits += nblocks;
+ transaction->t_outstanding_credits += nblocks;
+ result = 0;
+
+ jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
+unlock:
+ spin_unlock(&transaction->t_handle_lock);
+error_out:
+ spin_unlock(&journal->j_state_lock);
+out:
+ return result;
+}
+
+
+/**
+ * int journal_restart() - restart a handle .
+ * @handle: handle to restart
+ * @nblocks: nr credits requested
+ *
+ * Restart a handle for a multi-transaction filesystem
+ * operation.
+ *
+ * If the journal_extend() call above fails to grant new buffer credits
+ * to a running handle, a call to journal_restart will commit the
+ * handle's transaction so far and reattach the handle to a new
+ * transaction capabable of guaranteeing the requested number of
+ * credits.
+ */
+
+int journal_restart(handle_t *handle, int nblocks)
+{
+ transaction_t *transaction = handle->h_transaction;
+ journal_t *journal = transaction->t_journal;
+ int ret;
+
+ /* If we've had an abort of any type, don't even think about
+ * actually doing the restart! */
+ if (is_handle_aborted(handle))
+ return 0;
+
+ /*
+ * First unlink the handle from its current transaction, and start the
+ * commit on that.
+ */
+ J_ASSERT(transaction->t_updates > 0);
+ J_ASSERT(journal_current_handle() == handle);
+
+ spin_lock(&journal->j_state_lock);
+ spin_lock(&transaction->t_handle_lock);
+ transaction->t_outstanding_credits -= handle->h_buffer_credits;
+ transaction->t_updates--;
+
+ if (!transaction->t_updates)
+ wake_up(&journal->j_wait_updates);
+ spin_unlock(&transaction->t_handle_lock);
+
+ jbd_debug(2, "restarting handle %p\n", handle);
+ __log_start_commit(journal, transaction->t_tid);
+ spin_unlock(&journal->j_state_lock);
+
+ handle->h_buffer_credits = nblocks;
+ ret = start_this_handle(journal, handle);
+ return ret;
+}
+
+
+/**
+ * void journal_lock_updates () - establish a transaction barrier.
+ * @journal: Journal to establish a barrier on.
+ *
+ * This locks out any further updates from being started, and blocks
+ * until all existing updates have completed, returning only once the
+ * journal is in a quiescent state with no updates running.
+ *
+ * The journal lock should not be held on entry.
+ */
+void journal_lock_updates(journal_t *journal)
+{
+ DEFINE_WAIT(wait);
+
+ spin_lock(&journal->j_state_lock);
+ ++journal->j_barrier_count;
+
+ /* Wait until there are no running updates */
+ while (1) {
+ transaction_t *transaction = journal->j_running_transaction;
+
+ if (!transaction)
+ break;
+
+ spin_lock(&transaction->t_handle_lock);
+ if (!transaction->t_updates) {
+ spin_unlock(&transaction->t_handle_lock);
+ break;
+ }
+ prepare_to_wait(&journal->j_wait_updates, &wait,
+ TASK_UNINTERRUPTIBLE);
+ spin_unlock(&transaction->t_handle_lock);
+ spin_unlock(&journal->j_state_lock);
+ schedule();
+ finish_wait(&journal->j_wait_updates, &wait);
+ spin_lock(&journal->j_state_lock);
+ }
+ spin_unlock(&journal->j_state_lock);
+
+ /*
+ * We have now established a barrier against other normal updates, but
+ * we also need to barrier against other journal_lock_updates() calls
+ * to make sure that we serialise special journal-locked operations
+ * too.
+ */
+ mutex_lock(&journal->j_barrier);
+}
+
+/**
+ * void journal_unlock_updates (journal_t* journal) - release barrier
+ * @journal: Journal to release the barrier on.
+ *
+ * Release a transaction barrier obtained with journal_lock_updates().
+ *
+ * Should be called without the journal lock held.
+ */
+void journal_unlock_updates (journal_t *journal)
+{
+ J_ASSERT(journal->j_barrier_count != 0);
+
+ mutex_unlock(&journal->j_barrier);
+ spin_lock(&journal->j_state_lock);
+ --journal->j_barrier_count;
+ spin_unlock(&journal->j_state_lock);
+ wake_up(&journal->j_wait_transaction_locked);
+}
+
+/*
+ * Report any unexpected dirty buffers which turn up. Normally those
+ * indicate an error, but they can occur if the user is running (say)
+ * tune2fs to modify the live filesystem, so we need the option of
+ * continuing as gracefully as possible. #
+ *
+ * The caller should already hold the journal lock and
+ * j_list_lock spinlock: most callers will need those anyway
+ * in order to probe the buffer's journaling state safely.
+ */
+static void jbd_unexpected_dirty_buffer(struct journal_head *jh)
+{
+ int jlist;
+
+ /* If this buffer is one which might reasonably be dirty
+ * --- ie. data, or not part of this journal --- then
+ * we're OK to leave it alone, but otherwise we need to
+ * move the dirty bit to the journal's own internal
+ * JBDDirty bit. */
+ jlist = jh->b_jlist;
+
+ if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
+ jlist == BJ_Shadow || jlist == BJ_Forget) {
+ struct buffer_head *bh = jh2bh(jh);
+
+ if (test_clear_buffer_dirty(bh))
+ set_buffer_jbddirty(bh);
+ }
+}
+
+/*
+ * If the buffer is already part of the current transaction, then there
+ * is nothing we need to do. If it is already part of a prior
+ * transaction which we are still committing to disk, then we need to
+ * make sure that we do not overwrite the old copy: we do copy-out to
+ * preserve the copy going to disk. We also account the buffer against
+ * the handle's metadata buffer credits (unless the buffer is already
+ * part of the transaction, that is).
+ *
+ */
+static int
+do_get_write_access(handle_t *handle, struct journal_head *jh,
+ int force_copy)
+{
+ struct buffer_head *bh;
+ transaction_t *transaction;
+ journal_t *journal;
+ int error;
+ char *frozen_buffer = NULL;
+ int need_copy = 0;
+
+ if (is_handle_aborted(handle))
+ return -EROFS;
+
+ transaction = handle->h_transaction;
+ journal = transaction->t_journal;
+
+ jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
+
+ JBUFFER_TRACE(jh, "entry");
+repeat:
+ bh = jh2bh(jh);
+
+ /* @@@ Need to check for errors here at some point. */
+
+ lock_buffer(bh);
+ jbd_lock_bh_state(bh);
+
+ /* We now hold the buffer lock so it is safe to query the buffer
+ * state. Is the buffer dirty?
+ *
+ * If so, there are two possibilities. The buffer may be
+ * non-journaled, and undergoing a quite legitimate writeback.
+ * Otherwise, it is journaled, and we don't expect dirty buffers
+ * in that state (the buffers should be marked JBD_Dirty
+ * instead.) So either the IO is being done under our own
+ * control and this is a bug, or it's a third party IO such as
+ * dump(8) (which may leave the buffer scheduled for read ---
+ * ie. locked but not dirty) or tune2fs (which may actually have
+ * the buffer dirtied, ugh.) */
+
+ if (buffer_dirty(bh)) {
+ /*
+ * First question: is this buffer already part of the current
+ * transaction or the existing committing transaction?
+ */
+ if (jh->b_transaction) {
+ J_ASSERT_JH(jh,
+ jh->b_transaction == transaction ||
+ jh->b_transaction ==
+ journal->j_committing_transaction);
+ if (jh->b_next_transaction)
+ J_ASSERT_JH(jh, jh->b_next_transaction ==
+ transaction);
+ }
+ /*
+ * In any case we need to clean the dirty flag and we must
+ * do it under the buffer lock to be sure we don't race
+ * with running write-out.
+ */
+ JBUFFER_TRACE(jh, "Unexpected dirty buffer");
+ jbd_unexpected_dirty_buffer(jh);
+ }
+
+ unlock_buffer(bh);
+
+ error = -EROFS;
+ if (is_handle_aborted(handle)) {
+ jbd_unlock_bh_state(bh);
+ goto out;
+ }
+ error = 0;
+
+ /*
+ * The buffer is already part of this transaction if b_transaction or
+ * b_next_transaction points to it
+ */
+ if (jh->b_transaction == transaction ||
+ jh->b_next_transaction == transaction)
+ goto done;
+
+ /*
+ * If there is already a copy-out version of this buffer, then we don't
+ * need to make another one
+ */
+ if (jh->b_frozen_data) {
+ JBUFFER_TRACE(jh, "has frozen data");
+ J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
+ jh->b_next_transaction = transaction;
+ goto done;
+ }
+
+ /* Is there data here we need to preserve? */
+
+ if (jh->b_transaction && jh->b_transaction != transaction) {
+ JBUFFER_TRACE(jh, "owned by older transaction");
+ J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
+ J_ASSERT_JH(jh, jh->b_transaction ==
+ journal->j_committing_transaction);
+
+ /* There is one case we have to be very careful about.
+ * If the committing transaction is currently writing
+ * this buffer out to disk and has NOT made a copy-out,
+ * then we cannot modify the buffer contents at all
+ * right now. The essence of copy-out is that it is the
+ * extra copy, not the primary copy, which gets
+ * journaled. If the primary copy is already going to
+ * disk then we cannot do copy-out here. */
+
+ if (jh->b_jlist == BJ_Shadow) {
+ DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
+ wait_queue_head_t *wqh;
+
+ wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
+
+ JBUFFER_TRACE(jh, "on shadow: sleep");
+ jbd_unlock_bh_state(bh);
+ /* commit wakes up all shadow buffers after IO */
+ for ( ; ; ) {
+ prepare_to_wait(wqh, &wait.wait,
+ TASK_UNINTERRUPTIBLE);
+ if (jh->b_jlist != BJ_Shadow)
+ break;
+ schedule();
+ }
+ finish_wait(wqh, &wait.wait);
+ goto repeat;
+ }
+
+ /* Only do the copy if the currently-owning transaction
+ * still needs it. If it is on the Forget list, the
+ * committing transaction is past that stage. The
+ * buffer had better remain locked during the kmalloc,
+ * but that should be true --- we hold the journal lock
+ * still and the buffer is already on the BUF_JOURNAL
+ * list so won't be flushed.
+ *
+ * Subtle point, though: if this is a get_undo_access,
+ * then we will be relying on the frozen_data to contain
+ * the new value of the committed_data record after the
+ * transaction, so we HAVE to force the frozen_data copy
+ * in that case. */
+
+ if (jh->b_jlist != BJ_Forget || force_copy) {
+ JBUFFER_TRACE(jh, "generate frozen data");
+ if (!frozen_buffer) {
+ JBUFFER_TRACE(jh, "allocate memory for buffer");
+ jbd_unlock_bh_state(bh);
+ frozen_buffer =
+ jbd_slab_alloc(jh2bh(jh)->b_size,
+ GFP_NOFS);
+ if (!frozen_buffer) {
+ printk(KERN_EMERG
+ "%s: OOM for frozen_buffer\n",
+ __FUNCTION__);
+ JBUFFER_TRACE(jh, "oom!");
+ error = -ENOMEM;
+ jbd_lock_bh_state(bh);
+ goto done;
+ }
+ goto repeat;
+ }
+ jh->b_frozen_data = frozen_buffer;
+ frozen_buffer = NULL;
+ need_copy = 1;
+ }
+ jh->b_next_transaction = transaction;
+ }
+
+
+ /*
+ * Finally, if the buffer is not journaled right now, we need to make
+ * sure it doesn't get written to disk before the caller actually
+ * commits the new data
+ */
+ if (!jh->b_transaction) {
+ JBUFFER_TRACE(jh, "no transaction");
+ J_ASSERT_JH(jh, !jh->b_next_transaction);
+ jh->b_transaction = transaction;
+ JBUFFER_TRACE(jh, "file as BJ_Reserved");
+ spin_lock(&journal->j_list_lock);
+ __journal_file_buffer(jh, transaction, BJ_Reserved);
+ spin_unlock(&journal->j_list_lock);
+ }
+
+done:
+ if (need_copy) {
+ struct page *page;
+ int offset;
+ char *source;
+
+ J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
+ "Possible IO failure.\n");
+ page = jh2bh(jh)->b_page;
+ offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
+ source = kmap_atomic(page, KM_USER0);
+ memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
+ kunmap_atomic(source, KM_USER0);
+ }
+ jbd_unlock_bh_state(bh);
+
+ /*
+ * If we are about to journal a buffer, then any revoke pending on it is
+ * no longer valid
+ */
+ journal_cancel_revoke(handle, jh);
+
+out:
+ if (unlikely(frozen_buffer)) /* It's usually NULL */
+ jbd_slab_free(frozen_buffer, bh->b_size);
+
+ JBUFFER_TRACE(jh, "exit");
+ return error;
+}
+
+/**
+ * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
+ * @handle: transaction to add buffer modifications to
+ * @bh: bh to be used for metadata writes
+ * @credits: variable that will receive credits for the buffer
+ *
+ * Returns an error code or 0 on success.
+ *
+ * In full data journalling mode the buffer may be of type BJ_AsyncData,
+ * because we're write()ing a buffer which is also part of a shared mapping.
+ */
+
+int journal_get_write_access(handle_t *handle, struct buffer_head *bh)
+{
+ struct journal_head *jh = journal_add_journal_head(bh);
+ int rc;
+
+ /* We do not want to get caught playing with fields which the
+ * log thread also manipulates. Make sure that the buffer
+ * completes any outstanding IO before proceeding. */
+ rc = do_get_write_access(handle, jh, 0);
+ journal_put_journal_head(jh);
+ return rc;
+}
+
+
+/*
+ * When the user wants to journal a newly created buffer_head
+ * (ie. getblk() returned a new buffer and we are going to populate it
+ * manually rather than reading off disk), then we need to keep the
+ * buffer_head locked until it has been completely filled with new
+ * data. In this case, we should be able to make the assertion that
+ * the bh is not already part of an existing transaction.
+ *
+ * The buffer should already be locked by the caller by this point.
+ * There is no lock ranking violation: it was a newly created,
+ * unlocked buffer beforehand. */
+
+/**
+ * int journal_get_create_access () - notify intent to use newly created bh
+ * @handle: transaction to new buffer to
+ * @bh: new buffer.
+ *
+ * Call this if you create a new bh.
+ */
+int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
+{
+ transaction_t *transaction = handle->h_transaction;
+ journal_t *journal = transaction->t_journal;
+ struct journal_head *jh = journal_add_journal_head(bh);
+ int err;
+
+ jbd_debug(5, "journal_head %p\n", jh);
+ err = -EROFS;
+ if (is_handle_aborted(handle))
+ goto out;
+ err = 0;
+
+ JBUFFER_TRACE(jh, "entry");
+ /*
+ * The buffer may already belong to this transaction due to pre-zeroing
+ * in the filesystem's new_block code. It may also be on the previous,
+ * committing transaction's lists, but it HAS to be in Forget state in
+ * that case: the transaction must have deleted the buffer for it to be
+ * reused here.
+ */
+ jbd_lock_bh_state(bh);
+ spin_lock(&journal->j_list_lock);
+ J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
+ jh->b_transaction == NULL ||
+ (jh->b_transaction == journal->j_committing_transaction &&
+ jh->b_jlist == BJ_Forget)));
+
+ J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
+ J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
+
+ if (jh->b_transaction == NULL) {
+ jh->b_transaction = transaction;
+ JBUFFER_TRACE(jh, "file as BJ_Reserved");
+ __journal_file_buffer(jh, transaction, BJ_Reserved);
+ } else if (jh->b_transaction == journal->j_committing_transaction) {
+ JBUFFER_TRACE(jh, "set next transaction");
+ jh->b_next_transaction = transaction;
+ }
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+
+ /*
+ * akpm: I added this. ext3_alloc_branch can pick up new indirect
+ * blocks which contain freed but then revoked metadata. We need
+ * to cancel the revoke in case we end up freeing it yet again
+ * and the reallocating as data - this would cause a second revoke,
+ * which hits an assertion error.
+ */
+ JBUFFER_TRACE(jh, "cancelling revoke");
+ journal_cancel_revoke(handle, jh);
+ journal_put_journal_head(jh);
+out:
+ return err;
+}
+
+/**
+ * int journal_get_undo_access() - Notify intent to modify metadata with
+ * non-rewindable consequences
+ * @handle: transaction
+ * @bh: buffer to undo
+ * @credits: store the number of taken credits here (if not NULL)
+ *
+ * Sometimes there is a need to distinguish between metadata which has
+ * been committed to disk and that which has not. The ext3fs code uses
+ * this for freeing and allocating space, we have to make sure that we
+ * do not reuse freed space until the deallocation has been committed,
+ * since if we overwrote that space we would make the delete
+ * un-rewindable in case of a crash.
+ *
+ * To deal with that, journal_get_undo_access requests write access to a
+ * buffer for parts of non-rewindable operations such as delete
+ * operations on the bitmaps. The journaling code must keep a copy of
+ * the buffer's contents prior to the undo_access call until such time
+ * as we know that the buffer has definitely been committed to disk.
+ *
+ * We never need to know which transaction the committed data is part
+ * of, buffers touched here are guaranteed to be dirtied later and so
+ * will be committed to a new transaction in due course, at which point
+ * we can discard the old committed data pointer.
+ *
+ * Returns error number or 0 on success.
+ */
+int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
+{
+ int err;
+ struct journal_head *jh = journal_add_journal_head(bh);
+ char *committed_data = NULL;
+
+ JBUFFER_TRACE(jh, "entry");
+
+ /*
+ * Do this first --- it can drop the journal lock, so we want to
+ * make sure that obtaining the committed_data is done
+ * atomically wrt. completion of any outstanding commits.
+ */
+ err = do_get_write_access(handle, jh, 1);
+ if (err)
+ goto out;
+
+repeat:
+ if (!jh->b_committed_data) {
+ committed_data = jbd_slab_alloc(jh2bh(jh)->b_size, GFP_NOFS);
+ if (!committed_data) {
+ printk(KERN_EMERG "%s: No memory for committed data\n",
+ __FUNCTION__);
+ err = -ENOMEM;
+ goto out;
+ }
+ }
+
+ jbd_lock_bh_state(bh);
+ if (!jh->b_committed_data) {
+ /* Copy out the current buffer contents into the
+ * preserved, committed copy. */
+ JBUFFER_TRACE(jh, "generate b_committed data");
+ if (!committed_data) {
+ jbd_unlock_bh_state(bh);
+ goto repeat;
+ }
+
+ jh->b_committed_data = committed_data;
+ committed_data = NULL;
+ memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
+ }
+ jbd_unlock_bh_state(bh);
+out:
+ journal_put_journal_head(jh);
+ if (unlikely(committed_data))
+ jbd_slab_free(committed_data, bh->b_size);
+ return err;
+}
+
+/**
+ * int journal_dirty_data() - mark a buffer as containing dirty data which
+ * needs to be flushed before we can commit the
+ * current transaction.
+ * @handle: transaction
+ * @bh: bufferhead to mark
+ *
+ * The buffer is placed on the transaction's data list and is marked as
+ * belonging to the transaction.
+ *
+ * Returns error number or 0 on success.
+ *
+ * journal_dirty_data() can be called via page_launder->ext3_writepage
+ * by kswapd.
+ */
+int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
+{
+ journal_t *journal = handle->h_transaction->t_journal;
+ int need_brelse = 0;
+ struct journal_head *jh;
+
+ if (is_handle_aborted(handle))
+ return 0;
+
+ jh = journal_add_journal_head(bh);
+ JBUFFER_TRACE(jh, "entry");
+
+ /*
+ * The buffer could *already* be dirty. Writeout can start
+ * at any time.
+ */
+ jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
+
+ /*
+ * What if the buffer is already part of a running transaction?
+ *
+ * There are two cases:
+ * 1) It is part of the current running transaction. Refile it,
+ * just in case we have allocated it as metadata, deallocated
+ * it, then reallocated it as data.
+ * 2) It is part of the previous, still-committing transaction.
+ * If all we want to do is to guarantee that the buffer will be
+ * written to disk before this new transaction commits, then
+ * being sure that the *previous* transaction has this same
+ * property is sufficient for us! Just leave it on its old
+ * transaction.
+ *
+ * In case (2), the buffer must not already exist as metadata
+ * --- that would violate write ordering (a transaction is free
+ * to write its data at any point, even before the previous
+ * committing transaction has committed). The caller must
+ * never, ever allow this to happen: there's nothing we can do
+ * about it in this layer.
+ */
+ jbd_lock_bh_state(bh);
+ spin_lock(&journal->j_list_lock);
+ if (jh->b_transaction) {
+ JBUFFER_TRACE(jh, "has transaction");
+ if (jh->b_transaction != handle->h_transaction) {
+ JBUFFER_TRACE(jh, "belongs to older transaction");
+ J_ASSERT_JH(jh, jh->b_transaction ==
+ journal->j_committing_transaction);
+
+ /* @@@ IS THIS TRUE ? */
+ /*
+ * Not any more. Scenario: someone does a write()
+ * in data=journal mode. The buffer's transaction has
+ * moved into commit. Then someone does another
+ * write() to the file. We do the frozen data copyout
+ * and set b_next_transaction to point to j_running_t.
+ * And while we're in that state, someone does a
+ * writepage() in an attempt to pageout the same area
+ * of the file via a shared mapping. At present that
+ * calls journal_dirty_data(), and we get right here.
+ * It may be too late to journal the data. Simply
+ * falling through to the next test will suffice: the
+ * data will be dirty and wil be checkpointed. The
+ * ordering comments in the next comment block still
+ * apply.
+ */
+ //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
+
+ /*
+ * If we're journalling data, and this buffer was
+ * subject to a write(), it could be metadata, forget
+ * or shadow against the committing transaction. Now,
+ * someone has dirtied the same darn page via a mapping
+ * and it is being writepage()'d.
+ * We *could* just steal the page from commit, with some
+ * fancy locking there. Instead, we just skip it -
+ * don't tie the page's buffers to the new transaction
+ * at all.
+ * Implication: if we crash before the writepage() data
+ * is written into the filesystem, recovery will replay
+ * the write() data.
+ */
+ if (jh->b_jlist != BJ_None &&
+ jh->b_jlist != BJ_SyncData &&
+ jh->b_jlist != BJ_Locked) {
+ JBUFFER_TRACE(jh, "Not stealing");
+ goto no_journal;
+ }
+
+ /*
+ * This buffer may be undergoing writeout in commit. We
+ * can't return from here and let the caller dirty it
+ * again because that can cause the write-out loop in
+ * commit to never terminate.
+ */
+ if (buffer_dirty(bh)) {
+ get_bh(bh);
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ need_brelse = 1;
+ sync_dirty_buffer(bh);
+ jbd_lock_bh_state(bh);
+ spin_lock(&journal->j_list_lock);
+ /* The buffer may become locked again at any
+ time if it is redirtied */
+ }
+
+ /* journal_clean_data_list() may have got there first */
+ if (jh->b_transaction != NULL) {
+ JBUFFER_TRACE(jh, "unfile from commit");
+ __journal_temp_unlink_buffer(jh);
+ /* It still points to the committing
+ * transaction; move it to this one so
+ * that the refile assert checks are
+ * happy. */
+ jh->b_transaction = handle->h_transaction;
+ }
+ /* The buffer will be refiled below */
+
+ }
+ /*
+ * Special case --- the buffer might actually have been
+ * allocated and then immediately deallocated in the previous,
+ * committing transaction, so might still be left on that
+ * transaction's metadata lists.
+ */
+ if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
+ JBUFFER_TRACE(jh, "not on correct data list: unfile");
+ J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
+ __journal_temp_unlink_buffer(jh);
+ jh->b_transaction = handle->h_transaction;
+ JBUFFER_TRACE(jh, "file as data");
+ __journal_file_buffer(jh, handle->h_transaction,
+ BJ_SyncData);
+ }
+ } else {
+ JBUFFER_TRACE(jh, "not on a transaction");
+ __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
+ }
+no_journal:
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ if (need_brelse) {
+ BUFFER_TRACE(bh, "brelse");
+ __brelse(bh);
+ }
+ JBUFFER_TRACE(jh, "exit");
+ journal_put_journal_head(jh);
+ return 0;
+}
+
+/**
+ * int journal_dirty_metadata() - mark a buffer as containing dirty metadata
+ * @handle: transaction to add buffer to.
+ * @bh: buffer to mark
+ *
+ * mark dirty metadata which needs to be journaled as part of the current
+ * transaction.
+ *
+ * The buffer is placed on the transaction's metadata list and is marked
+ * as belonging to the transaction.
+ *
+ * Returns error number or 0 on success.
+ *
+ * Special care needs to be taken if the buffer already belongs to the
+ * current committing transaction (in which case we should have frozen
+ * data present for that commit). In that case, we don't relink the
+ * buffer: that only gets done when the old transaction finally
+ * completes its commit.
+ */
+int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
+{
+ transaction_t *transaction = handle->h_transaction;
+ journal_t *journal = transaction->t_journal;
+ struct journal_head *jh = bh2jh(bh);
+
+ jbd_debug(5, "journal_head %p\n", jh);
+ JBUFFER_TRACE(jh, "entry");
+ if (is_handle_aborted(handle))
+ goto out;
+
+ jbd_lock_bh_state(bh);
+
+ if (jh->b_modified == 0) {
+ /*
+ * This buffer's got modified and becoming part
+ * of the transaction. This needs to be done
+ * once a transaction -bzzz
+ */
+ jh->b_modified = 1;
+ J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
+ handle->h_buffer_credits--;
+ }
+
+ /*
+ * fastpath, to avoid expensive locking. If this buffer is already
+ * on the running transaction's metadata list there is nothing to do.
+ * Nobody can take it off again because there is a handle open.
+ * I _think_ we're OK here with SMP barriers - a mistaken decision will
+ * result in this test being false, so we go in and take the locks.
+ */
+ if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
+ JBUFFER_TRACE(jh, "fastpath");
+ J_ASSERT_JH(jh, jh->b_transaction ==
+ journal->j_running_transaction);
+ goto out_unlock_bh;
+ }
+
+ set_buffer_jbddirty(bh);
+
+ /*
+ * Metadata already on the current transaction list doesn't
+ * need to be filed. Metadata on another transaction's list must
+ * be committing, and will be refiled once the commit completes:
+ * leave it alone for now.
+ */
+ if (jh->b_transaction != transaction) {
+ JBUFFER_TRACE(jh, "already on other transaction");
+ J_ASSERT_JH(jh, jh->b_transaction ==
+ journal->j_committing_transaction);
+ J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
+ /* And this case is illegal: we can't reuse another
+ * transaction's data buffer, ever. */
+ goto out_unlock_bh;
+ }
+
+ /* That test should have eliminated the following case: */
+ J_ASSERT_JH(jh, jh->b_frozen_data == 0);
+
+ JBUFFER_TRACE(jh, "file as BJ_Metadata");
+ spin_lock(&journal->j_list_lock);
+ __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
+ spin_unlock(&journal->j_list_lock);
+out_unlock_bh:
+ jbd_unlock_bh_state(bh);
+out:
+ JBUFFER_TRACE(jh, "exit");
+ return 0;
+}
+
+/*
+ * journal_release_buffer: undo a get_write_access without any buffer
+ * updates, if the update decided in the end that it didn't need access.
+ *
+ */
+void
+journal_release_buffer(handle_t *handle, struct buffer_head *bh)
+{
+ BUFFER_TRACE(bh, "entry");
+}
+
+/**
+ * void journal_forget() - bforget() for potentially-journaled buffers.
+ * @handle: transaction handle
+ * @bh: bh to 'forget'
+ *
+ * We can only do the bforget if there are no commits pending against the
+ * buffer. If the buffer is dirty in the current running transaction we
+ * can safely unlink it.
+ *
+ * bh may not be a journalled buffer at all - it may be a non-JBD
+ * buffer which came off the hashtable. Check for this.
+ *
+ * Decrements bh->b_count by one.
+ *
+ * Allow this call even if the handle has aborted --- it may be part of
+ * the caller's cleanup after an abort.
+ */
+int journal_forget (handle_t *handle, struct buffer_head *bh)
+{
+ transaction_t *transaction = handle->h_transaction;
+ journal_t *journal = transaction->t_journal;
+ struct journal_head *jh;
+ int drop_reserve = 0;
+ int err = 0;
+
+ BUFFER_TRACE(bh, "entry");
+
+ jbd_lock_bh_state(bh);
+ spin_lock(&journal->j_list_lock);
+
+ if (!buffer_jbd(bh))
+ goto not_jbd;
+ jh = bh2jh(bh);
+
+ /* Critical error: attempting to delete a bitmap buffer, maybe?
+ * Don't do any jbd operations, and return an error. */
+ if (!J_EXPECT_JH(jh, !jh->b_committed_data,
+ "inconsistent data on disk")) {
+ err = -EIO;
+ goto not_jbd;
+ }
+
+ /*
+ * The buffer's going from the transaction, we must drop
+ * all references -bzzz
+ */
+ jh->b_modified = 0;
+
+ if (jh->b_transaction == handle->h_transaction) {
+ J_ASSERT_JH(jh, !jh->b_frozen_data);
+
+ /* If we are forgetting a buffer which is already part
+ * of this transaction, then we can just drop it from
+ * the transaction immediately. */
+ clear_buffer_dirty(bh);
+ clear_buffer_jbddirty(bh);
+
+ JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
+
+ drop_reserve = 1;
+
+ /*
+ * We are no longer going to journal this buffer.
+ * However, the commit of this transaction is still
+ * important to the buffer: the delete that we are now
+ * processing might obsolete an old log entry, so by
+ * committing, we can satisfy the buffer's checkpoint.
+ *
+ * So, if we have a checkpoint on the buffer, we should
+ * now refile the buffer on our BJ_Forget list so that
+ * we know to remove the checkpoint after we commit.
+ */
+
+ if (jh->b_cp_transaction) {
+ __journal_temp_unlink_buffer(jh);
+ __journal_file_buffer(jh, transaction, BJ_Forget);
+ } else {
+ __journal_unfile_buffer(jh);
+ journal_remove_journal_head(bh);
+ __brelse(bh);
+ if (!buffer_jbd(bh)) {
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ __bforget(bh);
+ goto drop;
+ }
+ }
+ } else if (jh->b_transaction) {
+ J_ASSERT_JH(jh, (jh->b_transaction ==
+ journal->j_committing_transaction));
+ /* However, if the buffer is still owned by a prior
+ * (committing) transaction, we can't drop it yet... */
+ JBUFFER_TRACE(jh, "belongs to older transaction");
+ /* ... but we CAN drop it from the new transaction if we
+ * have also modified it since the original commit. */
+
+ if (jh->b_next_transaction) {
+ J_ASSERT(jh->b_next_transaction == transaction);
+ jh->b_next_transaction = NULL;
+ drop_reserve = 1;
+ }
+ }
+
+not_jbd:
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ __brelse(bh);
+drop:
+ if (drop_reserve) {
+ /* no need to reserve log space for this block -bzzz */
+ handle->h_buffer_credits++;
+ }
+ return err;
+}
+
+/**
+ * int journal_stop() - complete a transaction
+ * @handle: tranaction to complete.
+ *
+ * All done for a particular handle.
+ *
+ * There is not much action needed here. We just return any remaining
+ * buffer credits to the transaction and remove the handle. The only
+ * complication is that we need to start a commit operation if the
+ * filesystem is marked for synchronous update.
+ *
+ * journal_stop itself will not usually return an error, but it may
+ * do so in unusual circumstances. In particular, expect it to
+ * return -EIO if a journal_abort has been executed since the
+ * transaction began.
+ */
+int journal_stop(handle_t *handle)
+{
+ transaction_t *transaction = handle->h_transaction;
+ journal_t *journal = transaction->t_journal;
+ int old_handle_count, err;
+ pid_t pid;
+
+ J_ASSERT(transaction->t_updates > 0);
+ J_ASSERT(journal_current_handle() == handle);
+
+ if (is_handle_aborted(handle))
+ err = -EIO;
+ else
+ err = 0;
+
+ if (--handle->h_ref > 0) {
+ jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
+ handle->h_ref);
+ return err;
+ }
+
+ jbd_debug(4, "Handle %p going down\n", handle);
+
+ /*
+ * Implement synchronous transaction batching. If the handle
+ * was synchronous, don't force a commit immediately. Let's
+ * yield and let another thread piggyback onto this transaction.
+ * Keep doing that while new threads continue to arrive.
+ * It doesn't cost much - we're about to run a commit and sleep
+ * on IO anyway. Speeds up many-threaded, many-dir operations
+ * by 30x or more...
+ *
+ * But don't do this if this process was the most recent one to
+ * perform a synchronous write. We do this to detect the case where a
+ * single process is doing a stream of sync writes. No point in waiting
+ * for joiners in that case.
+ */
+ pid = current->pid;
+ if (handle->h_sync && journal->j_last_sync_writer != pid) {
+ journal->j_last_sync_writer = pid;
+ do {
+ old_handle_count = transaction->t_handle_count;
+ schedule_timeout_uninterruptible(1);
+ } while (old_handle_count != transaction->t_handle_count);
+ }
+
+ current->journal_info = NULL;
+ spin_lock(&journal->j_state_lock);
+ spin_lock(&transaction->t_handle_lock);
+ transaction->t_outstanding_credits -= handle->h_buffer_credits;
+ transaction->t_updates--;
+ if (!transaction->t_updates) {
+ wake_up(&journal->j_wait_updates);
+ if (journal->j_barrier_count)
+ wake_up(&journal->j_wait_transaction_locked);
+ }
+
+ /*
+ * If the handle is marked SYNC, we need to set another commit
+ * going! We also want to force a commit if the current
+ * transaction is occupying too much of the log, or if the
+ * transaction is too old now.
+ */
+ if (handle->h_sync ||
+ transaction->t_outstanding_credits >
+ journal->j_max_transaction_buffers ||
+ time_after_eq(jiffies, transaction->t_expires)) {
+ /* Do this even for aborted journals: an abort still
+ * completes the commit thread, it just doesn't write
+ * anything to disk. */
+ tid_t tid = transaction->t_tid;
+
+ spin_unlock(&transaction->t_handle_lock);
+ jbd_debug(2, "transaction too old, requesting commit for "
+ "handle %p\n", handle);
+ /* This is non-blocking */
+ __log_start_commit(journal, transaction->t_tid);
+ spin_unlock(&journal->j_state_lock);
+
+ /*
+ * Special case: JFS_SYNC synchronous updates require us
+ * to wait for the commit to complete.
+ */
+ if (handle->h_sync && !(current->flags & PF_MEMALLOC))
+ err = log_wait_commit(journal, tid);
+ } else {
+ spin_unlock(&transaction->t_handle_lock);
+ spin_unlock(&journal->j_state_lock);
+ }
+
+ jbd_free_handle(handle);
+ return err;
+}
+
+/**int journal_force_commit() - force any uncommitted transactions
+ * @journal: journal to force
+ *
+ * For synchronous operations: force any uncommitted transactions
+ * to disk. May seem kludgy, but it reuses all the handle batching
+ * code in a very simple manner.
+ */
+int journal_force_commit(journal_t *journal)
+{
+ handle_t *handle;
+ int ret;
+
+ handle = journal_start(journal, 1);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ } else {
+ handle->h_sync = 1;
+ ret = journal_stop(handle);
+ }
+ return ret;
+}
+
+/*
+ *
+ * List management code snippets: various functions for manipulating the
+ * transaction buffer lists.
+ *
+ */
+
+/*
+ * Append a buffer to a transaction list, given the transaction's list head
+ * pointer.
+ *
+ * j_list_lock is held.
+ *
+ * jbd_lock_bh_state(jh2bh(jh)) is held.
+ */
+
+static inline void
+__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
+{
+ if (!*list) {
+ jh->b_tnext = jh->b_tprev = jh;
+ *list = jh;
+ } else {
+ /* Insert at the tail of the list to preserve order */
+ struct journal_head *first = *list, *last = first->b_tprev;
+ jh->b_tprev = last;
+ jh->b_tnext = first;
+ last->b_tnext = first->b_tprev = jh;
+ }
+}
+
+/*
+ * Remove a buffer from a transaction list, given the transaction's list
+ * head pointer.
+ *
+ * Called with j_list_lock held, and the journal may not be locked.
+ *
+ * jbd_lock_bh_state(jh2bh(jh)) is held.
+ */
+
+static inline void
+__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
+{
+ if (*list == jh) {
+ *list = jh->b_tnext;
+ if (*list == jh)
+ *list = NULL;
+ }
+ jh->b_tprev->b_tnext = jh->b_tnext;
+ jh->b_tnext->b_tprev = jh->b_tprev;
+}
+
+/*
+ * Remove a buffer from the appropriate transaction list.
+ *
+ * Note that this function can *change* the value of
+ * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
+ * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller
+ * is holding onto a copy of one of thee pointers, it could go bad.
+ * Generally the caller needs to re-read the pointer from the transaction_t.
+ *
+ * Called under j_list_lock. The journal may not be locked.
+ */
+void __journal_temp_unlink_buffer(struct journal_head *jh)
+{
+ struct journal_head **list = NULL;
+ transaction_t *transaction;
+ struct buffer_head *bh = jh2bh(jh);
+
+ J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
+ transaction = jh->b_transaction;
+ if (transaction)
+ assert_spin_locked(&transaction->t_journal->j_list_lock);
+
+ J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
+ if (jh->b_jlist != BJ_None)
+ J_ASSERT_JH(jh, transaction != 0);
+
+ switch (jh->b_jlist) {
+ case BJ_None:
+ return;
+ case BJ_SyncData:
+ list = &transaction->t_sync_datalist;
+ break;
+ case BJ_Metadata:
+ transaction->t_nr_buffers--;
+ J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
+ list = &transaction->t_buffers;
+ break;
+ case BJ_Forget:
+ list = &transaction->t_forget;
+ break;
+ case BJ_IO:
+ list = &transaction->t_iobuf_list;
+ break;
+ case BJ_Shadow:
+ list = &transaction->t_shadow_list;
+ break;
+ case BJ_LogCtl:
+ list = &transaction->t_log_list;
+ break;
+ case BJ_Reserved:
+ list = &transaction->t_reserved_list;
+ break;
+ case BJ_Locked:
+ list = &transaction->t_locked_list;
+ break;
+ }
+
+ __blist_del_buffer(list, jh);
+ jh->b_jlist = BJ_None;
+ if (test_clear_buffer_jbddirty(bh))
+ mark_buffer_dirty(bh); /* Expose it to the VM */
+}
+
+void __journal_unfile_buffer(struct journal_head *jh)
+{
+ __journal_temp_unlink_buffer(jh);
+ jh->b_transaction = NULL;
+}
+
+void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
+{
+ jbd_lock_bh_state(jh2bh(jh));
+ spin_lock(&journal->j_list_lock);
+ __journal_unfile_buffer(jh);
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(jh2bh(jh));
+}
+
+/*
+ * Called from journal_try_to_free_buffers().
+ *
+ * Called under jbd_lock_bh_state(bh)
+ */
+static void
+__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
+{
+ struct journal_head *jh;
+
+ jh = bh2jh(bh);
+
+ if (buffer_locked(bh) || buffer_dirty(bh))
+ goto out;
+
+ if (jh->b_next_transaction != 0)
+ goto out;
+
+ spin_lock(&journal->j_list_lock);
+ if (jh->b_transaction != 0 && jh->b_cp_transaction == 0) {
+ if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
+ /* A written-back ordered data buffer */
+ JBUFFER_TRACE(jh, "release data");
+ __journal_unfile_buffer(jh);
+ journal_remove_journal_head(bh);
+ __brelse(bh);
+ }
+ } else if (jh->b_cp_transaction != 0 && jh->b_transaction == 0) {
+ /* written-back checkpointed metadata buffer */
+ if (jh->b_jlist == BJ_None) {
+ JBUFFER_TRACE(jh, "remove from checkpoint list");
+ __journal_remove_checkpoint(jh);
+ journal_remove_journal_head(bh);
+ __brelse(bh);
+ }
+ }
+ spin_unlock(&journal->j_list_lock);
+out:
+ return;
+}
+
+
+/**
+ * int journal_try_to_free_buffers() - try to free page buffers.
+ * @journal: journal for operation
+ * @page: to try and free
+ * @unused_gfp_mask: unused
+ *
+ *
+ * For all the buffers on this page,
+ * if they are fully written out ordered data, move them onto BUF_CLEAN
+ * so try_to_free_buffers() can reap them.
+ *
+ * This function returns non-zero if we wish try_to_free_buffers()
+ * to be called. We do this if the page is releasable by try_to_free_buffers().
+ * We also do it if the page has locked or dirty buffers and the caller wants
+ * us to perform sync or async writeout.
+ *
+ * This complicates JBD locking somewhat. We aren't protected by the
+ * BKL here. We wish to remove the buffer from its committing or
+ * running transaction's ->t_datalist via __journal_unfile_buffer.
+ *
+ * This may *change* the value of transaction_t->t_datalist, so anyone
+ * who looks at t_datalist needs to lock against this function.
+ *
+ * Even worse, someone may be doing a journal_dirty_data on this
+ * buffer. So we need to lock against that. journal_dirty_data()
+ * will come out of the lock with the buffer dirty, which makes it
+ * ineligible for release here.
+ *
+ * Who else is affected by this? hmm... Really the only contender
+ * is do_get_write_access() - it could be looking at the buffer while
+ * journal_try_to_free_buffer() is changing its state. But that
+ * cannot happen because we never reallocate freed data as metadata
+ * while the data is part of a transaction. Yes?
+ */
+int journal_try_to_free_buffers(journal_t *journal,
+ struct page *page, gfp_t unused_gfp_mask)
+{
+ struct buffer_head *head;
+ struct buffer_head *bh;
+ int ret = 0;
+
+ J_ASSERT(PageLocked(page));
+
+ head = page_buffers(page);
+ bh = head;
+ do {
+ struct journal_head *jh;
+
+ /*
+ * We take our own ref against the journal_head here to avoid
+ * having to add tons of locking around each instance of
+ * journal_remove_journal_head() and journal_put_journal_head().
+ */
+ jh = journal_grab_journal_head(bh);
+ if (!jh)
+ continue;
+
+ jbd_lock_bh_state(bh);
+ __journal_try_to_free_buffer(journal, bh);
+ journal_put_journal_head(jh);
+ jbd_unlock_bh_state(bh);
+ if (buffer_jbd(bh))
+ goto busy;
+ } while ((bh = bh->b_this_page) != head);
+ ret = try_to_free_buffers(page);
+busy:
+ return ret;
+}
+
+/*
+ * This buffer is no longer needed. If it is on an older transaction's
+ * checkpoint list we need to record it on this transaction's forget list
+ * to pin this buffer (and hence its checkpointing transaction) down until
+ * this transaction commits. If the buffer isn't on a checkpoint list, we
+ * release it.
+ * Returns non-zero if JBD no longer has an interest in the buffer.
+ *
+ * Called under j_list_lock.
+ *
+ * Called under jbd_lock_bh_state(bh).
+ */
+static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
+{
+ int may_free = 1;
+ struct buffer_head *bh = jh2bh(jh);
+
+ __journal_unfile_buffer(jh);
+
+ if (jh->b_cp_transaction) {
+ JBUFFER_TRACE(jh, "on running+cp transaction");
+ __journal_file_buffer(jh, transaction, BJ_Forget);
+ clear_buffer_jbddirty(bh);
+ may_free = 0;
+ } else {
+ JBUFFER_TRACE(jh, "on running transaction");
+ journal_remove_journal_head(bh);
+ __brelse(bh);
+ }
+ return may_free;
+}
+
+/*
+ * journal_invalidatepage
+ *
+ * This code is tricky. It has a number of cases to deal with.
+ *
+ * There are two invariants which this code relies on:
+ *
+ * i_size must be updated on disk before we start calling invalidatepage on the
+ * data.
+ *
+ * This is done in ext3 by defining an ext3_setattr method which
+ * updates i_size before truncate gets going. By maintaining this
+ * invariant, we can be sure that it is safe to throw away any buffers
+ * attached to the current transaction: once the transaction commits,
+ * we know that the data will not be needed.
+ *
+ * Note however that we can *not* throw away data belonging to the
+ * previous, committing transaction!
+ *
+ * Any disk blocks which *are* part of the previous, committing
+ * transaction (and which therefore cannot be discarded immediately) are
+ * not going to be reused in the new running transaction
+ *
+ * The bitmap committed_data images guarantee this: any block which is
+ * allocated in one transaction and removed in the next will be marked
+ * as in-use in the committed_data bitmap, so cannot be reused until
+ * the next transaction to delete the block commits. This means that
+ * leaving committing buffers dirty is quite safe: the disk blocks
+ * cannot be reallocated to a different file and so buffer aliasing is
+ * not possible.
+ *
+ *
+ * The above applies mainly to ordered data mode. In writeback mode we
+ * don't make guarantees about the order in which data hits disk --- in
+ * particular we don't guarantee that new dirty data is flushed before
+ * transaction commit --- so it is always safe just to discard data
+ * immediately in that mode. --sct
+ */
+
+/*
+ * The journal_unmap_buffer helper function returns zero if the buffer
+ * concerned remains pinned as an anonymous buffer belonging to an older
+ * transaction.
+ *
+ * We're outside-transaction here. Either or both of j_running_transaction
+ * and j_committing_transaction may be NULL.
+ */
+static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
+{
+ transaction_t *transaction;
+ struct journal_head *jh;
+ int may_free = 1;
+ int ret;
+
+ BUFFER_TRACE(bh, "entry");
+
+ /*
+ * It is safe to proceed here without the j_list_lock because the
+ * buffers cannot be stolen by try_to_free_buffers as long as we are
+ * holding the page lock. --sct
+ */
+
+ if (!buffer_jbd(bh))
+ goto zap_buffer_unlocked;
+
+ spin_lock(&journal->j_state_lock);
+ jbd_lock_bh_state(bh);
+ spin_lock(&journal->j_list_lock);
+
+ jh = journal_grab_journal_head(bh);
+ if (!jh)
+ goto zap_buffer_no_jh;
+
+ transaction = jh->b_transaction;
+ if (transaction == NULL) {
+ /* First case: not on any transaction. If it
+ * has no checkpoint link, then we can zap it:
+ * it's a writeback-mode buffer so we don't care
+ * if it hits disk safely. */
+ if (!jh->b_cp_transaction) {
+ JBUFFER_TRACE(jh, "not on any transaction: zap");
+ goto zap_buffer;
+ }
+
+ if (!buffer_dirty(bh)) {
+ /* bdflush has written it. We can drop it now */
+ goto zap_buffer;
+ }
+
+ /* OK, it must be in the journal but still not
+ * written fully to disk: it's metadata or
+ * journaled data... */
+
+ if (journal->j_running_transaction) {
+ /* ... and once the current transaction has
+ * committed, the buffer won't be needed any
+ * longer. */
+ JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
+ ret = __dispose_buffer(jh,
+ journal->j_running_transaction);
+ journal_put_journal_head(jh);
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ spin_unlock(&journal->j_state_lock);
+ return ret;
+ } else {
+ /* There is no currently-running transaction. So the
+ * orphan record which we wrote for this file must have
+ * passed into commit. We must attach this buffer to
+ * the committing transaction, if it exists. */
+ if (journal->j_committing_transaction) {
+ JBUFFER_TRACE(jh, "give to committing trans");
+ ret = __dispose_buffer(jh,
+ journal->j_committing_transaction);
+ journal_put_journal_head(jh);
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ spin_unlock(&journal->j_state_lock);
+ return ret;
+ } else {
+ /* The orphan record's transaction has
+ * committed. We can cleanse this buffer */
+ clear_buffer_jbddirty(bh);
+ goto zap_buffer;
+ }
+ }
+ } else if (transaction == journal->j_committing_transaction) {
+ if (jh->b_jlist == BJ_Locked) {
+ /*
+ * The buffer is on the committing transaction's locked
+ * list. We have the buffer locked, so I/O has
+ * completed. So we can nail the buffer now.
+ */
+ may_free = __dispose_buffer(jh, transaction);
+ goto zap_buffer;
+ }
+ /*
+ * If it is committing, we simply cannot touch it. We
+ * can remove it's next_transaction pointer from the
+ * running transaction if that is set, but nothing
+ * else. */
+ JBUFFER_TRACE(jh, "on committing transaction");
+ set_buffer_freed(bh);
+ if (jh->b_next_transaction) {
+ J_ASSERT(jh->b_next_transaction ==
+ journal->j_running_transaction);
+ jh->b_next_transaction = NULL;
+ }
+ journal_put_journal_head(jh);
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ spin_unlock(&journal->j_state_lock);
+ return 0;
+ } else {
+ /* Good, the buffer belongs to the running transaction.
+ * We are writing our own transaction's data, not any
+ * previous one's, so it is safe to throw it away
+ * (remember that we expect the filesystem to have set
+ * i_size already for this truncate so recovery will not
+ * expose the disk blocks we are discarding here.) */
+ J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
+ may_free = __dispose_buffer(jh, transaction);
+ }
+
+zap_buffer:
+ journal_put_journal_head(jh);
+zap_buffer_no_jh:
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ spin_unlock(&journal->j_state_lock);
+zap_buffer_unlocked:
+ clear_buffer_dirty(bh);
+ J_ASSERT_BH(bh, !buffer_jbddirty(bh));
+ clear_buffer_mapped(bh);
+ clear_buffer_req(bh);
+ clear_buffer_new(bh);
+ bh->b_bdev = NULL;
+ return may_free;
+}
+
+/**
+ * void journal_invalidatepage()
+ * @journal: journal to use for flush...
+ * @page: page to flush
+ * @offset: length of page to invalidate.
+ *
+ * Reap page buffers containing data after offset in page.
+ *
+ */
+void journal_invalidatepage(journal_t *journal,
+ struct page *page,
+ unsigned long offset)
+{
+ struct buffer_head *head, *bh, *next;
+ unsigned int curr_off = 0;
+ int may_free = 1;
+
+ if (!PageLocked(page))
+ BUG();
+ if (!page_has_buffers(page))
+ return;
+
+ /* We will potentially be playing with lists other than just the
+ * data lists (especially for journaled data mode), so be
+ * cautious in our locking. */
+
+ head = bh = page_buffers(page);
+ do {
+ unsigned int next_off = curr_off + bh->b_size;
+ next = bh->b_this_page;
+
+ if (offset <= curr_off) {
+ /* This block is wholly outside the truncation point */
+ lock_buffer(bh);
+ may_free &= journal_unmap_buffer(journal, bh);
+ unlock_buffer(bh);
+ }
+ curr_off = next_off;
+ bh = next;
+
+ } while (bh != head);
+
+ if (!offset) {
+ if (may_free && try_to_free_buffers(page))
+ J_ASSERT(!page_has_buffers(page));
+ }
+}
+
+/*
+ * File a buffer on the given transaction list.
+ */
+void __journal_file_buffer(struct journal_head *jh,
+ transaction_t *transaction, int jlist)
+{
+ struct journal_head **list = NULL;
+ int was_dirty = 0;
+ struct buffer_head *bh = jh2bh(jh);
+
+ J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
+ assert_spin_locked(&transaction->t_journal->j_list_lock);
+
+ J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
+ J_ASSERT_JH(jh, jh->b_transaction == transaction ||
+ jh->b_transaction == 0);
+
+ if (jh->b_transaction && jh->b_jlist == jlist)
+ return;
+
+ /* The following list of buffer states needs to be consistent
+ * with __jbd_unexpected_dirty_buffer()'s handling of dirty
+ * state. */
+
+ if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
+ jlist == BJ_Shadow || jlist == BJ_Forget) {
+ if (test_clear_buffer_dirty(bh) ||
+ test_clear_buffer_jbddirty(bh))
+ was_dirty = 1;
+ }
+
+ if (jh->b_transaction)
+ __journal_temp_unlink_buffer(jh);
+ jh->b_transaction = transaction;
+
+ switch (jlist) {
+ case BJ_None:
+ J_ASSERT_JH(jh, !jh->b_committed_data);
+ J_ASSERT_JH(jh, !jh->b_frozen_data);
+ return;
+ case BJ_SyncData:
+ list = &transaction->t_sync_datalist;
+ break;
+ case BJ_Metadata:
+ transaction->t_nr_buffers++;
+ list = &transaction->t_buffers;
+ break;
+ case BJ_Forget:
+ list = &transaction->t_forget;
+ break;
+ case BJ_IO:
+ list = &transaction->t_iobuf_list;
+ break;
+ case BJ_Shadow:
+ list = &transaction->t_shadow_list;
+ break;
+ case BJ_LogCtl:
+ list = &transaction->t_log_list;
+ break;
+ case BJ_Reserved:
+ list = &transaction->t_reserved_list;
+ break;
+ case BJ_Locked:
+ list = &transaction->t_locked_list;
+ break;
+ }
+
+ __blist_add_buffer(list, jh);
+ jh->b_jlist = jlist;
+
+ if (was_dirty)
+ set_buffer_jbddirty(bh);
+}
+
+void journal_file_buffer(struct journal_head *jh,
+ transaction_t *transaction, int jlist)
+{
+ jbd_lock_bh_state(jh2bh(jh));
+ spin_lock(&transaction->t_journal->j_list_lock);
+ __journal_file_buffer(jh, transaction, jlist);
+ spin_unlock(&transaction->t_journal->j_list_lock);
+ jbd_unlock_bh_state(jh2bh(jh));
+}
+
+/*
+ * Remove a buffer from its current buffer list in preparation for
+ * dropping it from its current transaction entirely. If the buffer has
+ * already started to be used by a subsequent transaction, refile the
+ * buffer on that transaction's metadata list.
+ *
+ * Called under journal->j_list_lock
+ *
+ * Called under jbd_lock_bh_state(jh2bh(jh))
+ */
+void __journal_refile_buffer(struct journal_head *jh)
+{
+ int was_dirty;
+ struct buffer_head *bh = jh2bh(jh);
+
+ J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
+ if (jh->b_transaction)
+ assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
+
+ /* If the buffer is now unused, just drop it. */
+ if (jh->b_next_transaction == NULL) {
+ __journal_unfile_buffer(jh);
+ return;
+ }
+
+ /*
+ * It has been modified by a later transaction: add it to the new
+ * transaction's metadata list.
+ */
+
+ was_dirty = test_clear_buffer_jbddirty(bh);
+ __journal_temp_unlink_buffer(jh);
+ jh->b_transaction = jh->b_next_transaction;
+ jh->b_next_transaction = NULL;
+ __journal_file_buffer(jh, jh->b_transaction,
+ was_dirty ? BJ_Metadata : BJ_Reserved);
+ J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
+
+ if (was_dirty)
+ set_buffer_jbddirty(bh);
+}
+
+/*
+ * For the unlocked version of this call, also make sure that any
+ * hanging journal_head is cleaned up if necessary.
+ *
+ * __journal_refile_buffer is usually called as part of a single locked
+ * operation on a buffer_head, in which the caller is probably going to
+ * be hooking the journal_head onto other lists. In that case it is up
+ * to the caller to remove the journal_head if necessary. For the
+ * unlocked journal_refile_buffer call, the caller isn't going to be
+ * doing anything else to the buffer so we need to do the cleanup
+ * ourselves to avoid a jh leak.
+ *
+ * *** The journal_head may be freed by this call! ***
+ */
+void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
+{
+ struct buffer_head *bh = jh2bh(jh);
+
+ jbd_lock_bh_state(bh);
+ spin_lock(&journal->j_list_lock);
+
+ __journal_refile_buffer(jh);
+ jbd_unlock_bh_state(bh);
+ journal_remove_journal_head(bh);
+
+ spin_unlock(&journal->j_list_lock);
+ __brelse(bh);
+}