From: Jan Kara <jack@suse.cz>
To: Ted Tso <tytso@mit.edu>
Cc: <linux-ext4@vger.kernel.org>, Jan Kara <jack@suse.cz>,
Hao Sun <sunhao.th@gmail.com>
Subject: [PATCH 2/2] ext4: Annotate data race in jbd2_journal_dirty_metadata()
Date: Tue, 6 Apr 2021 18:18:00 +0200 [thread overview]
Message-ID: <20210406161804.20150-2-jack@suse.cz> (raw)
In-Reply-To: <20210406161605.2504-1-jack@suse.cz>
Assertion checks in jbd2_journal_dirty_metadata() are known to be racy
but we don't want to be grabbing locks just for them. We thus recheck
them under b_state_lock only if it looks like they would fail. Annotate
the checks with data_race().
Reported-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/jbd2/transaction.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 398d1d9209e2..e8fc45fd751f 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1479,8 +1479,8 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
* crucial to catch bugs so let's do a reliable check until the
* lockless handling is fully proven.
*/
- if (jh->b_transaction != transaction &&
- jh->b_next_transaction != transaction) {
+ if (data_race(jh->b_transaction != transaction &&
+ jh->b_next_transaction != transaction)) {
spin_lock(&jh->b_state_lock);
J_ASSERT_JH(jh, jh->b_transaction == transaction ||
jh->b_next_transaction == transaction);
@@ -1488,8 +1488,8 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
}
if (jh->b_modified == 1) {
/* If it's in our transaction it must be in BJ_Metadata list. */
- if (jh->b_transaction == transaction &&
- jh->b_jlist != BJ_Metadata) {
+ if (data_race(jh->b_transaction == transaction &&
+ jh->b_jlist != BJ_Metadata)) {
spin_lock(&jh->b_state_lock);
if (jh->b_transaction == transaction &&
jh->b_jlist != BJ_Metadata)
--
2.26.2
next prev parent reply other threads:[~2021-04-06 16:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-06 16:17 [PATCH 0/2] ext4: Annotate two harmless KCSAN data races Jan Kara
2021-04-06 16:17 ` [PATCH 1/2] ext4: Annotate data race in start_this_handle() Jan Kara
2021-04-10 1:24 ` Theodore Ts'o
2021-04-06 16:18 ` Jan Kara [this message]
2021-04-10 1:24 ` [PATCH 2/2] ext4: Annotate data race in jbd2_journal_dirty_metadata() Theodore Ts'o
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