linux-kernel - [GIT PULL] 9p cache=mmap regression fix (for 6.18-rc3)

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Message-ID: <aPgUaFE1oUq8e1F-@codewreck.org>
Date: Wed, 22 Oct 2025 08:16:56 +0900
From: Dominique Martinet <asmadeus@...ewreck.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Song Liu <song@...nel.org>, Andrii Nakryiko <andrii.nakryiko@...il.com>,
	Eric Van Hensbergen <ericvh@...nel.org>,
	Latchesar Ionkov <lucho@...kov.net>,
	Christian Schoenebeck <linux_oss@...debyte.com>,
	Tingmao Wang <m@...wtm.org>, Alexei Starovoitov <ast@...nel.org>,
	linux-kernel@...r.kernel.org, v9fs@...ts.linux.dev,
	bpf@...r.kernel.org
Subject: [GIT PULL] 9p cache=mmap regression fix (for 6.18-rc3)

Hi Linus,

We had a regression with cache=mmap that impacted quite a few people so
I'm sending a fix less than a couple of hours after making the commit.

If it turns out there are other side effects I'd suggest just reverting
commit 290434474c33 ("fs/9p: Refresh metadata in d_revalidate for
uncached mode too") first, but the fix is rather minimal so I think it's
ok to try falling forward -- let me know if you prefer a revert and I'll
send one instead (there's a minor conflict)

Thanks to Sung Liu for the minimal reproducer and testing, as well as
Alexei/Andrii and everyone else who looked at it.



The following changes since commit 211ddde0823f1442e4ad052a2f30f050145ccada:

  Linux 6.18-rc2 (2025-10-19 15:19:16 -1000)

are available in the Git repository at:

  https://github.com/martinetd/linux tags/9p-for-6.18-rc3

for you to fetch changes up to 2776e27d404684bc43acf023d7ca15255e96b3e3:

  fs/9p: don't use cached metadata in revalidate for cache=mmap (2025-10-22 08:04:05 +0900)

----------------------------------------------------------------
Fix regression with cache=mmap in 6.18-rc1

Will do some more testing as time allows but this fixes the immediate
issue minimally (only impacts cache=mmap), and is therefore an
improvement good enough to send right away.

----------------------------------------------------------------
Dominique Martinet (1):
      fs/9p: don't use cached metadata in revalidate for cache=mmap

 fs/9p/vfs_dentry.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

-- 
Dominique Martinet | Asmadeus