* Re: [PATCH v3] f2fs: do not support mmap write for large folio
[not found] ` <adaasm42rLxRY2GN@google.com>
@ 2026-04-09 5:40 ` Christoph Hellwig
2026-04-10 1:15 ` Jaegeuk Kim
0 siblings, 1 reply; 2+ messages in thread
From: Christoph Hellwig @ 2026-04-09 5:40 UTC (permalink / raw)
To: Jaegeuk Kim; +Cc: linux-kernel, linux-f2fs-devel, linux-fsdevel, linux-mm
[adding back fsdevel and mm to the discussion]
On Wed, Apr 08, 2026 at 06:13:06PM +0000, Jaegeuk Kim wrote:
> Let's check mmap writes onto the large folio, since we don't support writing
> large folios.
What does this fix? As state in the previous round of discussion f2fs
only support large folios for immutable files, how do you get ->mkwrite
called for them.
The only way I can think of that is when clearing the immutable flag,
but simply rejecting writes with SIGBUS after that seems like it's
breaking the expected API, and I don't see handling for normal writes
after that either.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v3] f2fs: do not support mmap write for large folio
2026-04-09 5:40 ` [PATCH v3] f2fs: do not support mmap write for large folio Christoph Hellwig
@ 2026-04-10 1:15 ` Jaegeuk Kim
0 siblings, 0 replies; 2+ messages in thread
From: Jaegeuk Kim @ 2026-04-10 1:15 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: linux-kernel, linux-f2fs-devel, linux-fsdevel, linux-mm
On 04/08, Christoph Hellwig wrote:
> [adding back fsdevel and mm to the discussion]
>
> On Wed, Apr 08, 2026 at 06:13:06PM +0000, Jaegeuk Kim wrote:
> > Let's check mmap writes onto the large folio, since we don't support writing
> > large folios.
>
> What does this fix? As state in the previous round of discussion f2fs
> only support large folios for immutable files, how do you get ->mkwrite
> called for them.
I'm approaching this as a safeguard first, since in any buggy case, this will
crash the filesystem.
>
> The only way I can think of that is when clearing the immutable flag,
> but simply rejecting writes with SIGBUS after that seems like it's
> breaking the expected API, and I don't see handling for normal writes
> after that either.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-04-09 5:40 ` [PATCH v3] f2fs: do not support mmap write for large folio Christoph Hellwig
2026-04-10 1:15 ` Jaegeuk Kim
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