Re: [PATCH v2] ext4: don't fail journal recovery on an incomplete fast commit

[sashiko-bot@kernel.org]

> If the system crashes while the first fast commit after a full commit is
> being written, the fast commit area can hold the head of that fast
> commit without a valid tail.  ext4_fc_replay_scan() treats this as an
> error as long as no valid tail has been seen: an invalid tag length or
> an unknown tag returns -ECANCELED, a tail with a wrong tid or checksum
> returns -EFSBADCRC.  jbd2_journal_recover() then fails, the file system
> can be mounted neither read-write nor read-only, and the regular journal
> transactions committed before the fast commit are not replayed either:
> 
>   JBD2: journal recovery failed
>   EXT4-fs (sdb): error loading journal
> 
> The tail is written last and fsync() does not return before it has
> completed, so an incomplete fast commit was never reported as durable.
> Handle it like jbd2 handles a transaction without a valid commit block:
> [ ... ]
> which case the full commit is now replayed as well.
> 
> Fixes: 8016e29f4362 ("ext4: fast commit recovery path")
> Assisted-by: Claude Opus 5.5
> Signed-off-by: Hsiu-Hsien Lee <swinds24@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261007040829.2074386-1-swinds24@gmail.com?part=1