Re: [PATCH] jbd2: don't start a fast commit while the journal is marked empty

[sashiko-bot@kernel.org]

> From: Daejun Park <daejun7.park@samsung.com>
> 
> jbd2_journal_flush() checkpoints everything, and
> jbd2_mark_journal_empty() then writes the journal superblock with
> s_start == 0 and the fast commit feature cleared. It sets JBD2_FLUSHED
> so that the next commit writes the log tail and the feature back, but
> only jbd2_journal_commit_transaction() looks at that flag. A fast commit
> started before the next full commit writes its blocks while the
> superblock on disk still says the log is empty: jbd2_journal_recover()
> returns at once and the fast commit is never replayed.
> 
> On ext4 with -O fast_commit this happens after ext4_freeze(), and after
> a remount to read-only, which flushes the journal in
> ext4_mark_recovery_complete(), once the file system is read-write again.
> EXT4_IOC_CHECKPOINT and online resize flush it as well. An fsync that a
> [ ... ]
> as it does for the existing check.
> 
> Fixes: ff780b91efe9 ("jbd2: add fast commit machinery")
> Cc: stable@vger.kernel.org
> Signed-off-by: Daejun Park <daejun7.park@samsung.com>

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

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Sashiko AI review · https://sashiko.dev/#/patchset/20261007-jbd2-fc-after-flush-v1-1-548bd91cd959@samsung.com?part=1