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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 08:46:23 -0800
commit3a06c3ff07f7a00a48edbe264987cc33f409a6d5 (patch)
treedbf4c80057f376a36cd9b600feb4150481fb9ecf /fs
parent7b563c7c8d2297ee7063b69c151e741b3d4b6eac (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')
-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 a74ba4659549..6873d2476715 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -209,7 +209,8 @@ 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;
}