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: [email protected]
Signed-off-by: Camila Alvarez <[email protected]>
---
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
On Wed, May 15, 2024 at 11:19:20PM -0400, 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.
I think this is correct, but we should try to come up with some better
assertions or something to make the code clearer; we don't want off by
ones to lurk so easily.
Could you give it some thought?
>
> Reported-by: [email protected]
> Signed-off-by: Camila Alvarez <[email protected]>
> ---
> 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
>
On Sun, 19 May 2024, Kent Overstreet wrote:
> On Wed, May 15, 2024 at 11:19:20PM -0400, 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.
>
> I think this is correct, but we should try to come up with some better
> assertions or something to make the code clearer; we don't want off by
> ones to lurk so easily.
>
> Could you give it some thought?
>
You're right. I think the code is written in a confusing way. In
particular it seems that cur_seq - 1 is used all over the place.
I believe we can abstract cur_seq - 1 in an independent variable (since
it represents the actual last sequence number), that should make it
clearer.
I'll share an updated version of the patch.
Thanks for the response!
>>
>> Reported-by: [email protected]
>> Signed-off-by: Camila Alvarez <[email protected]>
>> ---
>> 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
>>
>