On Sun, Mar 23, 2025 at 07:34:59PM +0800, Nanzhe Zhao wrote:
> I've recently been studying your patch 'f2fs: Remove uses of
> writepage'. I understand the rationale behind it, especially with the
> page cache and file I/O increasingly adopting folios in place of the
> traditional page structure. This trend indeed renders the legacy
> `writepage` function in file systems not only unnecessary but
> potentially detrimental. This is particularly true for file systems
> like F2FS, which, as you know, has already fully implemented the
> `writepages` function for all its `address_space_operations`.
>
> However, as you've pointed out, the `pageout` function within vmscan,
> which `kswapd` uses for dirty page writeback, doesn't currently
> support calling the file system's
> `address_space_operations->writepages`. I was wondering if you have
> any plans to improve this situation, and if so, could you perhaps
> share some insights into the general direction or approach you might
> be considering?
commit 21b4ee7029c9
Author: Dave Chinner <dchin...@redhat.com>
Date: Tue Aug 10 18:33:41 2021 -0700
xfs: drop ->writepage completely
->writepage is only used in one place - single page writeback from
memory reclaim. We only allow such writeback from kswapd, not from
direct memory reclaim, and so it is rarely used. When it comes from
kswapd, it is effectively random dirty page shoot-down, which is
horrible for IO patterns. We will already have background writeback
trying to clean all the dirty pages in memory as efficiently as
possible, so having kswapd interrupt our well formed IO stream only
slows things down. So get rid of xfs_vm_writepage() completely.
Signed-off-by: Dave Chinner <dchin...@redhat.com>
[djwong: forward port to 5.15]
Reviewed-by: Darrick J. Wong <djw...@kernel.org>
Signed-off-by: Darrick J. Wong <djw...@kernel.org>
https://lore.kernel.org/linux-fsdevel/20181109151239.gd9...@infradead.org/
There's probably some other good documentation around why we're doing
this, but this is all I have handy.
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