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authorJan Kara <jack@suse.cz>2012-12-21 00:15:51 -0500
committerTheodore Ts'o <tytso@mit.edu>2012-12-21 00:15:51 -0500
commitd7961c7fa4d2e3c3f12be67e21ba8799b5a7238a (patch)
tree3341ce3bdff7f2283e18f0cb02c438f421d746b0
parent261cb20cb2f0737a247aaf08dff7eb065e3e5b66 (diff)
downloadop-kernel-dev-d7961c7fa4d2e3c3f12be67e21ba8799b5a7238a.zip
op-kernel-dev-d7961c7fa4d2e3c3f12be67e21ba8799b5a7238a.tar.gz
jbd2: fix assertion failure in jbd2_journal_flush()
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> Cc: stable@vger.kernel.org
-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 deffd94..cd4485d 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;
}
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