jbd2: don't read journal->j_commit_sequence without taking a lock

Take journal state lock before reading journal->j_commit_sequence. Signed-off-by: Harshad Shirwadkar <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Theodore Ts'o <[email protected]>
ambv · Nov 7, 2020 · 480f89d · 480f89d
1 parent 0ee66dd
commit 480f89d
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
@@ -734,10 +734,12 @@ int jbd2_fc_begin_commit(journal_t *journal, tid_t tid)
 	if (!journal->j_stats.ts_tid)
 		return -EINVAL;
 
-	if (tid <= journal->j_commit_sequence)
+	write_lock(&journal->j_state_lock);
+	if (tid <= journal->j_commit_sequence) {
+		write_unlock(&journal->j_state_lock);
 		return -EALREADY;
+	}
 
-	write_lock(&journal->j_state_lock);
 	if (journal->j_flags & JBD2_FULL_COMMIT_ONGOING ||
 	    (journal->j_flags & JBD2_FAST_COMMIT_ONGOING)) {
 		DEFINE_WAIT(wait);