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authorJan Kara <jack@suse.cz>2012-12-21 00:15:51 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-01-17 08:43:57 -0800
commit7c558b7eb837ca7bc014af2f5509be143c3c3670 (patch)
tree3fda987d2dee62aa3517630b7649ee63b31d9cf5 /fs/jbd2
parent8cbe63802ddac6b242e4a4293fc338fa7808272c (diff)
jbd2: fix assertion failure in jbd2_journal_flush()
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: yjwsignal@empal.com Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/jbd2')
-rw-r--r--fs/jbd2/transaction.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 9baa39ea6be..4ef2aae0e66 100644
--- 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;
}