Re: [PATCH RFC v3 03/14] ext4: use sb_find_get_block_nonatomic() in ext4_get_inode_loc_noio()

[sashiko-bot@kernel.org]

> ext4_get_inode_loc_noio() looks the inode table block up with
> sb_find_get_block(). That's the atomic lookup. It serializes against
> try_to_free_buffers() with i_private_lock instead of the folio lock and
> gives up if the folio is being migrated. So it can report the block as
> not cached while it is.
> 
> For ext4_fc_snapshot_inode() that only means falling back to a full
> commit. But ext4_sync_inode_metadata() is going to use
> ext4_get_inode_loc_noio() to find the inode block that fsync() has to
> write out and there a dirty block must not be skipped.
> 
> ext4_fc_snapshot_inode() is the only caller and it can sleep. It runs
> under jbd2_journal_lock_updates() and allocates the snapshot with
> GFP_NOFS. So use sb_find_get_block_nonatomic() which takes the folio
> lock and waits for the migration instead.
> 
> Suggested-by: Jan Kara <jack@suse.cz>
> Cc: stable@vger.kernel.org # v7.3
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261109-work-inode-metadata_writeback-v3-0-91ac6c024018@kernel.org?part=3