From: Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com>
To: ocfs2-devel@oss.oracle.com
Cc: rajesh.sivaramasubramaniom@oracle.com
Subject: [Ocfs2-devel] [PATCH RFC 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head
Date: Thu, 30 Sep 2021 12:27:39 +0530 [thread overview]
Message-ID: <1632985059-11984-1-git-send-email-gautham.ananthakrishna@oracle.com> (raw)
Encountered a race between ocfs2_test_bg_bit_allocatable() and
jbd2_journal_put_journal_head() due to which ocfs2_test_bg_bit_allocatable()
dereferenced NULL pointer. When ocfs2_test_bg_bit_allocatable() called bh2jh(bg_bh),
the bg_bh->b_private was NULL as jbd2_journal_put_journal_head() raced and released
the journal_head from the buffer head. Needed to take bit lock for the bit
'BH_JournalHead' to fix this race.
Signed-off-by: Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com>
---
fs/ocfs2/suballoc.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 8521942..0e4e11b 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -1256,8 +1256,11 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
return 0;
- if (!buffer_jbd(bg_bh))
+ jbd_lock_bh_journal_head(bg_bh);
+ if (!buffer_jbd(bg_bh)){
+ jbd_unlock_bh_journal_head(bg_bh);
return 1;
+ }
jh = bh2jh(bg_bh);
spin_lock(&jh->b_state_lock);
@@ -1267,6 +1270,7 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
else
ret = 1;
spin_unlock(&jh->b_state_lock);
+ jbd_unlock_bh_journal_head(bg_bh);
return ret;
}
--
1.8.3.1
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next reply other threads:[~2021-10-08 15:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-30 6:57 Gautham Ananthakrishna [this message]
2021-10-05 11:54 [Ocfs2-devel] [PATCH RFC 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head Gautham Ananthakrishna
2021-10-08 6:39 ` Joseph Qi
2021-10-13 4:08 ` Gautham Ananthakrishna
2021-10-13 8:08 ` Joseph Qi
2021-10-19 14:14 ` Gautham Ananthakrishna
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