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-rw-r--r--Documentation/filesystems/ext4.txt2
-rw-r--r--fs/ext4/Kconfig1
-rw-r--r--fs/ext4/block_validity.c1
-rw-r--r--fs/ext4/extents.c28
-rw-r--r--fs/ext4/fsync.c16
-rw-r--r--fs/ext4/inode.c171
-rw-r--r--fs/ext4/mballoc.h1
-rw-r--r--fs/ext4/super.c6
-rw-r--r--fs/ext4/xattr.c2
-rw-r--r--fs/fs-writeback.c17
-rw-r--r--fs/jbd2/checkpoint.c15
-rw-r--r--fs/jbd2/commit.c19
-rw-r--r--fs/jbd2/journal.c2
-rw-r--r--include/linux/jbd2.h1
-rw-r--r--include/linux/writeback.h1
15 files changed, 189 insertions, 94 deletions
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index af6885c3c82..e1def1786e5 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -196,7 +196,7 @@ nobarrier This also requires an IO stack which can support
also be used to enable or disable barriers, for
consistency with other ext4 mount options.
-inode_readahead=n This tuning parameter controls the maximum
+inode_readahead_blks=n This tuning parameter controls the maximum
number of inode table blocks that ext4's inode
table readahead algorithm will pre-read into
the buffer cache. The default value is 32 blocks.
diff --git a/fs/ext4/Kconfig b/fs/ext4/Kconfig
index 9acf7e80813..9ed1bb1f319 100644
--- a/fs/ext4/Kconfig
+++ b/fs/ext4/Kconfig
@@ -28,6 +28,7 @@ config EXT4_FS
config EXT4_USE_FOR_EXT23
bool "Use ext4 for ext2/ext3 file systems"
+ depends on EXT4_FS
depends on EXT3_FS=n || EXT2_FS=n
default y
help
diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index 4df8621ec31..a60ab9aad57 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -16,7 +16,6 @@
#include <linux/module.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
-#include <linux/version.h>
#include <linux/blkdev.h>
#include <linux/mutex.h>
#include "ext4.h"
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 3a7928f825e..91ae46098ea 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3023,6 +3023,14 @@ out:
return err;
}
+static void unmap_underlying_metadata_blocks(struct block_device *bdev,
+ sector_t block, int count)
+{
+ int i;
+ for (i = 0; i < count; i++)
+ unmap_underlying_metadata(bdev, block + i);
+}
+
static int
ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
ext4_lblk_t iblock, unsigned int max_blocks,
@@ -3098,6 +3106,18 @@ out:
} else
allocated = ret;
set_buffer_new(bh_result);
+ /*
+ * if we allocated more blocks than requested
+ * we need to make sure we unmap the extra block
+ * allocated. The actual needed block will get
+ * unmapped later when we find the buffer_head marked
+ * new.
+ */
+ if (allocated > max_blocks) {
+ unmap_underlying_metadata_blocks(inode->i_sb->s_bdev,
+ newblock + max_blocks,
+ allocated - max_blocks);
+ }
map_out:
set_buffer_mapped(bh_result);
out1:
@@ -3190,7 +3210,13 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
* this situation is possible, though, _during_ tree modification;
* this is why assert can't be put in ext4_ext_find_extent()
*/
- BUG_ON(path[depth].p_ext == NULL && depth != 0);
+ if (path[depth].p_ext == NULL && depth != 0) {
+ ext4_error(inode->i_sb, __func__, "bad extent address "
+ "inode: %lu, iblock: %d, depth: %d",
+ inode->i_ino, iblock, depth);
+ err = -EIO;
+ goto out2;
+ }
eh = path[depth].p_hdr;
ex = path[depth].p_ext;
diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index 0b22497d92e..98bd140aad0 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -88,9 +88,21 @@ int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync)
return ext4_force_commit(inode->i_sb);
commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
- if (jbd2_log_start_commit(journal, commit_tid))
+ if (jbd2_log_start_commit(journal, commit_tid)) {
+ /*
+ * When the journal is on a different device than the
+ * fs data disk, we need to issue the barrier in
+ * writeback mode. (In ordered mode, the jbd2 layer
+ * will take care of issuing the barrier. In
+ * data=journal, all of the data blocks are written to
+ * the journal device.)
+ */
+ if (ext4_should_writeback_data(inode) &&
+ (journal->j_fs_dev != journal->j_dev) &&
+ (journal->j_flags & JBD2_BARRIER))
+ blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
jbd2_log_wait_commit(journal, commit_tid);
- else if (journal->j_flags & JBD2_BARRIER)
+ } else if (journal->j_flags & JBD2_BARRIER)
blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
return ret;
}
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ab807963a61..84eeb8f515a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1043,43 +1043,47 @@ static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
return ext4_indirect_calc_metadata_amount(inode, blocks);
}
+/*
+ * Called with i_data_sem down, which is important since we can call
+ * ext4_discard_preallocations() from here.
+ */
static void ext4_da_update_reserve_space(struct inode *inode, int used)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
- int total, mdb, mdb_free, mdb_claim = 0;
-
- spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
- /* recalculate the number of metablocks still need to be reserved */
- total = EXT4_I(inode)->i_reserved_data_blocks - used;
- mdb = ext4_calc_metadata_amount(inode, total);
-
- /* figure out how many metablocks to release */
- BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
- mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;
-
- if (mdb_free) {
- /* Account for allocated meta_blocks */
- mdb_claim = EXT4_I(inode)->i_allocated_meta_blocks;
- BUG_ON(mdb_free < mdb_claim);
- mdb_free -= mdb_claim;
-
- /* update fs dirty blocks counter */
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ int mdb_free = 0;
+
+ spin_lock(&ei->i_block_reservation_lock);
+ if (unlikely(used > ei->i_reserved_data_blocks)) {
+ ext4_msg(inode->i_sb, KERN_NOTICE, "%s: ino %lu, used %d "
+ "with only %d reserved data blocks\n",
+ __func__, inode->i_ino, used,
+ ei->i_reserved_data_blocks);
+ WARN_ON(1);
+ used = ei->i_reserved_data_blocks;
+ }
+
+ /* Update per-inode reservations */
+ ei->i_reserved_data_blocks -= used;
+ used += ei->i_allocated_meta_blocks;
+ ei->i_reserved_meta_blocks -= ei->i_allocated_meta_blocks;
+ ei->i_allocated_meta_blocks = 0;
+ percpu_counter_sub(&sbi->s_dirtyblocks_counter, used);
+
+ if (ei->i_reserved_data_blocks == 0) {
+ /*
+ * We can release all of the reserved metadata blocks
+ * only when we have written all of the delayed
+ * allocation blocks.
+ */
+ mdb_free = ei->i_allocated_meta_blocks;
percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free);
- EXT4_I(inode)->i_allocated_meta_blocks = 0;
- EXT4_I(inode)->i_reserved_meta_blocks = mdb;
+ ei->i_allocated_meta_blocks = 0;
}
-
- /* update per-inode reservations */
- BUG_ON(used > EXT4_I(inode)->i_reserved_data_blocks);
- EXT4_I(inode)->i_reserved_data_blocks -= used;
- percpu_counter_sub(&sbi->s_dirtyblocks_counter, used + mdb_claim);
spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
- vfs_dq_claim_block(inode, used + mdb_claim);
-
- /*
- * free those over-booking quota for metadata blocks
- */
+ /* Update quota subsystem */
+ vfs_dq_claim_block(inode, used);
if (mdb_free)
vfs_dq_release_reservation_block(inode, mdb_free);
@@ -1088,7 +1092,8 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
* there aren't any writers on the inode, we can discard the
* inode's preallocations.
*/
- if (!total && (atomic_read(&inode->i_writecount) == 0))
+ if ((ei->i_reserved_data_blocks == 0) &&
+ (atomic_read(&inode->i_writecount) == 0))
ext4_discard_preallocations(inode);
}
@@ -1801,7 +1806,8 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
{
int retries = 0;
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
- unsigned long md_needed, mdblocks, total = 0;
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ unsigned long md_needed, md_reserved, total = 0;
/*
* recalculate the amount of metadata blocks to reserve
@@ -1809,35 +1815,44 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
* worse case is one extent per block
*/
repeat:
- spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
- total = EXT4_I(inode)->i_reserved_data_blocks + nrblocks;
- mdblocks = ext4_calc_metadata_amount(inode, total);
- BUG_ON(mdblocks < EXT4_I(inode)->i_reserved_meta_blocks);
-
- md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks;
+ spin_lock(&ei->i_block_reservation_lock);
+ md_reserved = ei->i_reserved_meta_blocks;
+ md_needed = ext4_calc_metadata_amount(inode, nrblocks);
total = md_needed + nrblocks;
- spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+ spin_unlock(&ei->i_block_reservation_lock);
/*
* Make quota reservation here to prevent quota overflow
* later. Real quota accounting is done at pages writeout
* time.
*/
- if (vfs_dq_reserve_block(inode, total))
+ if (vfs_dq_reserve_block(inode, total)) {
+ /*
+ * We tend to badly over-estimate the amount of
+ * metadata blocks which are needed, so if we have
+ * reserved any metadata blocks, try to force out the
+ * inode and see if we have any better luck.
+ */
+ if (md_reserved && retries++ <= 3)
+ goto retry;
return -EDQUOT;
+ }
if (ext4_claim_free_blocks(sbi, total)) {
vfs_dq_release_reservation_block(inode, total);
if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
+ retry:
+ if (md_reserved)
+ write_inode_now(inode, (retries == 3));
yield();
goto repeat;
}
return -ENOSPC;
}
- spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
- EXT4_I(inode)->i_reserved_data_blocks += nrblocks;
- EXT4_I(inode)->i_reserved_meta_blocks += md_needed;
- spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+ spin_lock(&ei->i_block_reservation_lock);
+ ei->i_reserved_data_blocks += nrblocks;
+ ei->i_reserved_meta_blocks += md_needed;
+ spin_unlock(&ei->i_block_reservation_lock);
return 0; /* success */
}
@@ -1845,49 +1860,45 @@ repeat:
static void ext4_da_release_space(struct inode *inode, int to_free)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
- int total, mdb, mdb_free, release;
+ struct ext4_inode_info *ei = EXT4_I(inode);
if (!to_free)
return; /* Nothing to release, exit */
spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
- if (!EXT4_I(inode)->i_reserved_data_blocks) {
+ if (unlikely(to_free > ei->i_reserved_data_blocks)) {
/*
- * if there is no reserved blocks, but we try to free some
- * then the counter is messed up somewhere.
- * but since this function is called from invalidate
- * page, it's harmless to return without any action
+ * if there aren't enough reserved blocks, then the
+ * counter is messed up somewhere. Since this
+ * function is called from invalidate page, it's
+ * harmless to return without any action.
*/
- printk(KERN_INFO "ext4 delalloc try to release %d reserved "
- "blocks for inode %lu, but there is no reserved "
- "data blocks\n", to_free, inode->i_ino);
- spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
- return;
+ ext4_msg(inode->i_sb, KERN_NOTICE, "ext4_da_release_space: "
+ "ino %lu, to_free %d with only %d reserved "
+ "data blocks\n", inode->i_ino, to_free,
+ ei->i_reserved_data_blocks);
+ WARN_ON(1);
+ to_free = ei->i_reserved_data_blocks;
}
+ ei->i_reserved_data_blocks -= to_free;
- /* recalculate the number of metablocks still need to be reserved */
- total = EXT4_I(inode)->i_reserved_data_blocks - to_free;
- mdb = ext4_calc_metadata_amount(inode, total);
-
- /* figure out how many metablocks to release */
- BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
- mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;
-
- release = to_free + mdb_free;
-
- /* update fs dirty blocks counter for truncate case */
- percpu_counter_sub(&sbi->s_dirtyblocks_counter, release);
+ if (ei->i_reserved_data_blocks == 0) {
+ /*
+ * We can release all of the reserved metadata blocks
+ * only when we have written all of the delayed
+ * allocation blocks.
+ */
+ to_free += ei->i_allocated_meta_blocks;
+ ei->i_allocated_meta_blocks = 0;
+ }
- /* update per-inode reservations */
- BUG_ON(to_free > EXT4_I(inode)->i_reserved_data_blocks);
- EXT4_I(inode)->i_reserved_data_blocks -= to_free;
+ /* update fs dirty blocks counter */
+ percpu_counter_sub(&sbi->s_dirtyblocks_counter, to_free);
- BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
- EXT4_I(inode)->i_reserved_meta_blocks = mdb;
spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
- vfs_dq_release_reservation_block(inode, release);
+ vfs_dq_release_reservation_block(inode, to_free);
}
static void ext4_da_page_release_reservation(struct page *page,
@@ -2967,8 +2978,7 @@ retry:
out_writepages:
if (!no_nrwrite_index_update)
wbc->no_nrwrite_index_update = 0;
- if (wbc->nr_to_write > nr_to_writebump)
- wbc->nr_to_write -= nr_to_writebump;
+ wbc->nr_to_write -= nr_to_writebump;
wbc->range_start = range_start;
trace_ext4_da_writepages_result(inode, wbc, ret, pages_written);
return ret;
@@ -2993,11 +3003,18 @@ static int ext4_nonda_switch(struct super_block *sb)
if (2 * free_blocks < 3 * dirty_blocks ||
free_blocks < (dirty_blocks + EXT4_FREEBLOCKS_WATERMARK)) {
/*
- * free block count is less that 150% of dirty blocks
- * or free blocks is less that watermark
+ * free block count is less than 150% of dirty blocks
+ * or free blocks is less than watermark
*/
return 1;
}
+ /*
+ * Even if we don't switch but are nearing capacity,
+ * start pushing delalloc when 1/2 of free blocks are dirty.
+ */
+ if (free_blocks < 2 * dirty_blocks)
+ writeback_inodes_sb_if_idle(sb);
+
return 0;
}
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index 0ca811061bc..436521cae45 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -17,7 +17,6 @@
#include <linux/proc_fs.h>
#include <linux/pagemap.h>
#include <linux/seq_file.h>
-#include <linux/version.h>
#include <linux/blkdev.h>
#include <linux/mutex.h>
#include "ext4_jbd2.h"
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 6ed9aa91f27..7cccb35c0f4 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2174,9 +2174,9 @@ static ssize_t lifetime_write_kbytes_show(struct ext4_attr *a,
struct super_block *sb = sbi->s_buddy_cache->i_sb;
return snprintf(buf, PAGE_SIZE, "%llu\n",
- sbi->s_kbytes_written +
+ (unsigned long long)(sbi->s_kbytes_written +
((part_stat_read(sb->s_bdev->bd_part, sectors[1]) -
- EXT4_SB(sb)->s_sectors_written_start) >> 1));
+ EXT4_SB(sb)->s_sectors_written_start) >> 1)));
}
static ssize_t inode_readahead_blks_store(struct ext4_attr *a,
@@ -4005,6 +4005,7 @@ static inline void unregister_as_ext2(void)
{
unregister_filesystem(&ext2_fs_type);
}
+MODULE_ALIAS("ext2");
#else
static inline void register_as_ext2(void) { }
static inline void unregister_as_ext2(void) { }
@@ -4031,6 +4032,7 @@ static inline void unregister_as_ext3(void)
{
unregister_filesystem(&ext3_fs_type);
}
+MODULE_ALIAS("ext3");
#else
static inline void register_as_ext3(void) { }
static inline void unregister_as_ext3(void) { }
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 83218bebbc7..f3a2f7ed45a 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1332,6 +1332,8 @@ retry:
goto cleanup;
kfree(b_entry_name);
kfree(buffer);
+ b_entry_name = NULL;
+ buffer = NULL;
brelse(is->iloc.bh);
kfree(is);
kfree(bs);
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 49bc1b8e8f1..f6c2155e002 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1187,6 +1187,23 @@ void writeback_inodes_sb(struct super_block *sb)
EXPORT_SYMBOL(writeback_inodes_sb);
/**
+ * writeback_inodes_sb_if_idle - start writeback if none underway
+ * @sb: the superblock
+ *
+ * Invoke writeback_inodes_sb if no writeback is currently underway.
+ * Returns 1 if writeback was started, 0 if not.
+ */
+int writeback_inodes_sb_if_idle(struct super_block *sb)
+{
+ if (!writeback_in_progress(sb->s_bdi)) {
+ writeback_inodes_sb(sb);
+ return 1;
+ } else
+ return 0;
+}
+EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
+
+/**
* sync_inodes_sb - sync sb inode pages
* @sb: the superblock
*
diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index ca0f5eb62b2..88684937095 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -22,6 +22,7 @@
#include <linux/jbd2.h>
#include <linux/errno.h>
#include <linux/slab.h>
+#include <linux/blkdev.h>
#include <trace/events/jbd2.h>
/*
@@ -515,6 +516,20 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
journal->j_tail_sequence = first_tid;
journal->j_tail = blocknr;
spin_unlock(&journal->j_state_lock);
+
+ /*
+ * If there is an external journal, we need to make sure that
+ * any data blocks that were recently written out --- perhaps
+ * by jbd2_log_do_checkpoint() --- are flushed out before we
+ * drop the transactions from the external journal. It's
+ * unlikely this will be necessary, especially with a
+ * appropriately sized journal, but we need this to guarantee
+ * correctness. Fortunately jbd2_cleanup_journal_tail()
+ * doesn't get called all that often.
+ */
+ if ((journal->j_fs_dev != journal->j_dev) &&
+ (journal->j_flags & JBD2_BARRIER))
+ blkdev_issue_flush(journal->j_fs_dev, NULL);
if (!(journal->j_flags & JBD2_ABORT))
jbd2_journal_update_superblock(journal, 1);
return 0;
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 6a10238d2c6..1bc74b6f26d 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -259,6 +259,7 @@ static int journal_submit_data_buffers(journal_t *journal,
ret = err;
spin_lock(&journal->j_list_lock);
J_ASSERT(jinode->i_transaction == commit_transaction);
+ commit_transaction->t_flushed_data_blocks = 1;
jinode->i_flags &= ~JI_COMMIT_RUNNING;
wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
}
@@ -708,8 +709,17 @@ start_journal_io:
}
}
- /* Done it all: now write the commit record asynchronously. */
+ /*
+ * If the journal is not located on the file system device,
+ * then we must flush the file system device before we issue
+ * the commit record
+ */
+ if (commit_transaction->t_flushed_data_blocks &&
+ (journal->j_fs_dev != journal->j_dev) &&
+ (journal->j_flags & JBD2_BARRIER))
+ blkdev_issue_flush(journal->j_fs_dev, NULL);
+ /* Done it all: now write the commit record asynchronously. */
if (JBD2_HAS_INCOMPAT_FEATURE(journal,
JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
err = journal_submit_commit_record(journal, commit_transaction,
@@ -720,13 +730,6 @@ start_journal_io:
blkdev_issue_flush(journal->j_dev, NULL);
}
- /*
- * This is the right place to wait for data buffers both for ASYNC
- * and !ASYNC commit. If commit is ASYNC, we need to wait only after
- * the commit block went to disk (which happens above). If commit is
- * SYNC, we need to wait for data buffers before we start writing
- * commit block, which happens below in such setting.
- */
err = journal_finish_inode_data_buffers(journal, commit_transaction);
if (err) {
printk(KERN_WARNING
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 17af879e6e9..ac0d027595d 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -814,7 +814,7 @@ static journal_t * journal_init_common (void)
journal_t *journal;
int err;
- journal = kzalloc(sizeof(*journal), GFP_KERNEL|__GFP_NOFAIL);
+ journal = kzalloc(sizeof(*journal), GFP_KERNEL);
if (!journal)
goto fail;
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index f1011f7f3d4..638ce4554c7 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -653,6 +653,7 @@ struct transaction_s
* waiting for it to finish.
*/
unsigned int t_synchronous_commit:1;
+ unsigned int t_flushed_data_blocks:1;
/*
* For use by the filesystem to store fs-specific data
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index c18c008f4bb..76e8903cd20 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -70,6 +70,7 @@ struct writeback_control {
struct bdi_writeback;
int inode_wait(void *);
void writeback_inodes_sb(struct super_block *);
+int writeback_inodes_sb_if_idle(struct super_block *);
void sync_inodes_sb(struct super_block *);
void writeback_inodes_wbc(struct writeback_control *wbc);
long wb_do_writeback(struct bdi_writeback *wb, int force_wait);