path: root/fs/jbd/commit.c
diff options
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/commit.c
parentmm: fix XIP file writes (diff)
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/commit.c')
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c
index 8f1f2aa5fb39..610264b99a8e 100644
--- a/fs/jbd/commit.c
+++ b/fs/jbd/commit.c
@@ -858,10 +858,10 @@ restart_loop:
- * 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
+ * This is a bit sleazy. We use j_list_lock to protect transition
+ * of a transaction into T_FINISHED state and calling
+ * __journal_drop_transaction(). Otherwise we could race with
+ * other checkpointing code processing the transaction...