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authorJan Kara <jack@suse.cz>2007-12-04 23:45:27 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-12-05 09:21:20 -0800
commitd4beaf4ab5f89496f2bcf67db62ad95d99bfeff6 (patch)
treeae6d005199017e9a0ade169fd69cb73d6c0ac88f /fs/jbd/checkpoint.c
parent369b8f5a70402d9fe77006cd0044c8a3fcd08430 (diff)
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jbd: Fix assertion failure in fs/jbd/checkpoint.c
Before we start committing a transaction, we call __journal_clean_checkpoint_list() to cleanup transaction's written-back buffers. If this call happens to remove all of them (and there were already some buffers), __journal_remove_checkpoint() will decide to free the transaction because it isn't (yet) a committing transaction and soon we fail some assertion - the transaction really isn't ready to be freed :). We change the check in __journal_remove_checkpoint() to free only a transaction in T_FINISHED state. The locking there is subtle though (as everywhere in JBD ;(). We use j_list_lock to protect the check and a subsequent call to __journal_drop_transaction() and do the same in the end of journal_commit_transaction() which is the only place where a transaction can get to T_FINISHED state. Probably I'm too paranoid here and such locking is not really necessary - checkpoint lists are processed only from log_do_checkpoint() where a transaction must be already committed to be processed or from __journal_clean_checkpoint_list() where kjournald itself calls it and thus transaction cannot change state either. Better be safe if something changes in future... Signed-off-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/jbd/checkpoint.c')
-rw-r--r--fs/jbd/checkpoint.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/fs/jbd/checkpoint.c b/fs/jbd/checkpoint.c
index 47552d4a632..0f69c416eeb 100644
--- a/fs/jbd/checkpoint.c
+++ b/fs/jbd/checkpoint.c
@@ -602,15 +602,15 @@ int __journal_remove_checkpoint(struct journal_head *jh)
/*
* 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!
+ * buffer off a running or committing transaction's checkpoing 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.
+ * The locking here around t_state 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");
+ if (transaction->t_state != T_FINISHED) {
+ JBUFFER_TRACE(jh, "belongs to running/committing transaction");
goto out;
}