This is a note to let you know that I've just added the patch titled
jbd2: fix assertion failure in jbd2_journal_flush()
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
jbd2-fix-assertion-failure-in-jbd2_journal_flush.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From d7961c7fa4d2e3c3f12be67e21ba8799b5a7238a Mon Sep 17 00:00:00 2001
From: Jan Kara <[email protected]>
Date: Fri, 21 Dec 2012 00:15:51 -0500
Subject: jbd2: fix assertion failure in jbd2_journal_flush()
From: Jan Kara <[email protected]>
commit d7961c7fa4d2e3c3f12be67e21ba8799b5a7238a upstream.
The following race is possible between start_this_handle() and someone
calling jbd2_journal_flush().
Process A Process B
start_this_handle().
if (journal->j_barrier_count) # false
if (!journal->j_running_transaction) { #true
read_unlock(&journal->j_state_lock);
jbd2_journal_lock_updates()
jbd2_journal_flush()
write_lock(&journal->j_state_lock);
if (journal->j_running_transaction) {
# false
... wait for committing trans ...
write_unlock(&journal->j_state_lock);
...
write_lock(&journal->j_state_lock);
if (!journal->j_running_transaction) { # true
jbd2_get_transaction(journal, new_transaction);
write_unlock(&journal->j_state_lock);
goto repeat; # eventually blocks on j_barrier_count > 0
...
J_ASSERT(!journal->j_running_transaction);
# fails
We fix the race by rechecking j_barrier_count after reacquiring j_state_lock
in exclusive mode.
Reported-by: [email protected]
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: "Theodore Ts'o" <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/jbd2/transaction.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -178,7 +178,8 @@ repeat:
if (!new_transaction)
goto alloc_transaction;
write_lock(&journal->j_state_lock);
- if (!journal->j_running_transaction) {
+ if (!journal->j_running_transaction &&
+ !journal->j_barrier_count) {
jbd2_get_transaction(journal, new_transaction);
new_transaction = NULL;
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/jbd2-fix-assertion-failure-in-jbd2_journal_flush.patch
queue-3.0/udf-don-t-increment-lenextents-while-writing-to-a-hole.patch
queue-3.0/udf-fix-memory-leak-while-allocating-blocks-during-write.patch
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