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authorJan Kara <jack@suse.cz>2008-01-29 07:58:27 +0300
committerTheodore Ts'o <tytso@mit.edu>2008-01-29 07:58:27 +0300
commitf5a7a6b0d9b6af7d46124ed3f6b3995225cb62d0 (patch)
treecbb2bc79a488461bf3bec9b60d15e21717dc8360 /fs/jbd2/checkpoint.c
parent36df53f4a3e445175fc1e9d7f433599482ec6d7f (diff)
downloadlinux-f5a7a6b0d9b6af7d46124ed3f6b3995225cb62d0.tar.xz
jbd2: Fix assertion failure in fs/jbd2/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>
Diffstat (limited to 'fs/jbd2/checkpoint.c')
-rw-r--r--fs/jbd2/checkpoint.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index 3fccde7ba008..7e958c86242f 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -602,15 +602,15 @@ int __jbd2_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 jbd2_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;
}