linux-kernel - Re: [PATCH v2] fs: move fd_install() slowpath into a dedicated routine and provide commentary

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Message-ID: <CAGudoHGTOLXH=BtiU+ja9vbdR=cMCLFTDmtHtCNa32yka6huRg@mail.gmail.com>
Date: Wed, 12 Nov 2025 11:31:42 +0100
From: Mateusz Guzik <mjguzik@...il.com>
To: Christian Brauner <brauner@...nel.org>
Cc: jack@...e.cz, linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	viro@...iv.linux.org.uk
Subject: Re: [PATCH v2] fs: move fd_install() slowpath into a dedicated
 routine and provide commentary

this may get the dreaded missing arg description working, how about this on top:
diff --git a/fs/file.c b/fs/file.c
index 3f56890068aa..022e98525c65 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -641,8 +641,10 @@ void put_unused_fd(unsigned int fd)

 EXPORT_SYMBOL(put_unused_fd);

-/*
- * Install a file pointer in the fd array while it is being resized.
+/**
+ * fd_install_slowpath - install a file pointer in the fd array while
it is being resized
+ * @fd: file descriptor to install the file in
+ * @file: the file to install
  *
  * We need to make sure our update to the array does not get lost as
the resizing
  * thread can be copying the content as we modify it.

On Wed, Nov 12, 2025 at 10:30 AM Christian Brauner <brauner@...nel.org> wrote:
>
> On Mon, 10 Nov 2025 10:56:34 +0100, Mateusz Guzik wrote:
> > On stock kernel gcc 14 emits avoidable register spillage:
> >       endbr64
> >       call   ffffffff81374630 <__fentry__>
> >       push   %r13
> >       push   %r12
> >       push   %rbx
> >       sub    $0x8,%rsp
> >       [snip]
> >
> > [...]
>
> Applied to the vfs-6.19.misc branch of the vfs/vfs.git tree.
> Patches in the vfs-6.19.misc branch should appear in linux-next soon.
>
> Please report any outstanding bugs that were missed during review in a
> new review to the original patch series allowing us to drop it.
>
> It's encouraged to provide Acked-bys and Reviewed-bys even though the
> patch has now been applied. If possible patch trailers will be updated.
>
> Note that commit hashes shown below are subject to change due to rebase,
> trailer updates or similar. If in doubt, please check the listed branch.
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
> branch: vfs-6.19.misc
>
> [1/1] fs: move fd_install() slowpath into a dedicated routine and provide commentary
>       https://git.kernel.org/vfs/vfs/c/6ecf5292038e