Re: [syzbot] [PATCH] bcachefs: fix last_seq and last_empty_seq in bch2_fs_journal_start()

syzbot
2024-05-16T01:53:35Z

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Subject: [PATCH] bcachefs: fix last_seq and last_empty_seq in bch2_fs_journal_start()
Author: cam.alvarez.i@gmail.com

#syz test
Values were left as the next possible sequence number when there were no
entries.

The fix involves updating the last_seq initial value and
setting last_empty_seq to cur_seq - 1.

Signed-off-by: Camila Alvarez <cam.alvarez.i@gmail.com>
---
fs/bcachefs/journal.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
index adec8e1ea73e..3835c458eec9 100644
--- a/fs/bcachefs/journal.c
+++ b/fs/bcachefs/journal.c
@@ -1196,7 +1196,7 @@ int bch2_fs_journal_start(struct journal *j, u64 cur_seq)
struct journal_replay *i, **_i;
struct genradix_iter iter;
bool had_entries = false;
- u64 last_seq = cur_seq, nr, seq;
+ u64 last_seq = cur_seq - 1, nr, seq;

genradix_for_each_reverse(&c->journal_entries, iter, _i) {
i = *_i;
@@ -1256,7 +1256,7 @@ int bch2_fs_journal_start(struct journal *j, u64 cur_seq)
}

if (!had_entries)
- j->last_empty_seq = cur_seq;
+ j->last_empty_seq = cur_seq - 1;

spin_lock(&j->lock);

--
2.34.1