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Message-ID: <cf7d1a86-b1e4-08ee-0d99-0b3f2823fb47@macbook-pro-de-camila.local>
Date: Mon, 27 May 2024 15:25:39 -0400 (-04)
From: Camila Alvarez Inostroza <cam.alvarez.i@...il.com>
To: Camila Alvarez <cam.alvarez.i@...il.com>
cc: Kent Overstreet <kent.overstreet@...ux.dev>,
Brian Foster <bfoster@...hat.com>, linux-bcachefs@...r.kernel.org,
linux-kernel@...r.kernel.org,
syzbot+10b936c5eaee2819b49b@...kaller.appspotmail.com
Subject: Re: [PATCH v2] bcachefs: fix last_seq and last_empty_seq in
bch2_fs_journal_start()
Hello,
I was wondering if you had had the time to take a look at this.
Please let me know if there's something I'm missing.
Thanks!
On Sun, 19 May 2024, Camila Alvarez wrote:
> 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.
>
> Reported-by: syzbot+10b936c5eaee2819b49b@...kaller.appspotmail.com
> Signed-off-by: Camila Alvarez <cam.alvarez.i@...il.com>
> ---
> Changes in v2:
> - Introduce a new variable to distinguish the last sequence number, from
> the last written sequence number
> - Abstract `cur_seq - 1` into a variable named `last_seq`
> - Reference to the last sequence number are changed from `cur_seq - 1`
> to `last_seq`
> ---
> fs/bcachefs/journal.c | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
> index adec8e1ea73e..99fc32f0382d 100644
> --- a/fs/bcachefs/journal.c
> +++ b/fs/bcachefs/journal.c
> @@ -1195,8 +1195,8 @@ int bch2_fs_journal_start(struct journal *j, u64 cur_seq)
> struct journal_entry_pin_list *p;
> struct journal_replay *i, **_i;
> struct genradix_iter iter;
> - bool had_entries = false;
> - u64 last_seq = cur_seq, nr, seq;
> + bool had_entries = false;
> + u64 last_written_seq = cur_seq - 1, last_seq = cur_seq - 1, nr, seq;
>
> genradix_for_each_reverse(&c->journal_entries, iter, _i) {
> i = *_i;
> @@ -1204,11 +1204,11 @@ int bch2_fs_journal_start(struct journal *j, u64 cur_seq)
> if (journal_replay_ignore(i))
> continue;
>
> - last_seq = le64_to_cpu(i->j.last_seq);
> + last_written_seq = le64_to_cpu(i->j.last_seq);
> break;
> }
>
> - nr = cur_seq - last_seq;
> + nr = cur_seq - last_written_seq;
>
> if (nr + 1 > j->pin.size) {
> free_fifo(&j->pin);
> @@ -1219,14 +1219,14 @@ int bch2_fs_journal_start(struct journal *j, u64 cur_seq)
> }
> }
>
> - j->replay_journal_seq = last_seq;
> + j->replay_journal_seq = last_written_seq;
> j->replay_journal_seq_end = cur_seq;
> - j->last_seq_ondisk = last_seq;
> - j->flushed_seq_ondisk = cur_seq - 1;
> - j->seq_ondisk = cur_seq - 1;
> - j->pin.front = last_seq;
> + j->last_seq_ondisk = last_written_seq;
> + j->flushed_seq_ondisk = last_seq;
> + j->seq_ondisk = last_seq;
> + j->pin.front = last_written_seq;
> j->pin.back = cur_seq;
> - atomic64_set(&j->seq, cur_seq - 1);
> + atomic64_set(&j->seq, last_seq);
>
> fifo_for_each_entry_ptr(p, &j->pin, seq)
> journal_pin_list_init(p, 1);
> @@ -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 = last_seq;
>
> spin_lock(&j->lock);
>
> --
> 2.34.1
>
>
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