Re: [PATCH 13/13] ext4: allow large folios for encrypted files

[sashiko-bot@kernel.org]

> Encrypted filesystems keep their folio order at s_min_folio_order,
> because the read path could not handle a folio that covers a data
> unit number wraparound.  The read path now sends such folios to the
> buffer_head based path, so drop the restriction and give large folios
> to all encrypted files, including the ones whose block size is not
> larger than the page size.
> 
> Writes and direct I/O don't need the same treatment: ext4_writepages()
> checks fscrypt_mergeable_bio() for every block, so a write bio never
> spans a wraparound, and the bios of direct I/O are cut at the block
> size.
> 
> Performance:
> 
> Hardware: 96-core machine, 3.84T NVMe, 512G memory
> Filesystem: ext4 with a 4k block size, encryption on the fallback path
> 
> Buffered sequential writes (1G, fsync) in MiB/s; medians of 3 runs.
> 
>   bs      Before     After    gain
>   ----    ------    ------    ----
>   4k        1118      1162     +4%
>   16k       1260      1756    +39%
>   64k       1272      1977    +55%
>   256k      1308      2081    +59%
>   1M        1260      1455    +15%
> 
> Signed-off-by: Baokun Li <libaokun@linux.alibaba.com>

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

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Sashiko AI review · https://sashiko.dev/#/patchset/20261011170958.1759230-1-libaokun@linux.alibaba.com?part=13