[PATCH 1/1] backing-file: convert to using fops->splice_write

[PATCH 1/1] backing-file: convert to using fops->splice_write

[ed.tsai]

From: Ed Tsai <ed.tsai@mediatek.com>

Filesystems may define their own splice write. Therefore, use the file
fops instead of invoking iter_file_splice_write() directly.

Signed-off-by: Ed Tsai <ed.tsai@mediatek.com>
---
 fs/backing-file.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/backing-file.c b/fs/backing-file.c
index afb557446c27..8860dac58c37 100644
--- a/fs/backing-file.c
+++ b/fs/backing-file.c
@@ -303,13 +303,16 @@ ssize_t backing_file_splice_write(struct pipe_inode_info *pipe,
 	if (WARN_ON_ONCE(!(out->f_mode & FMODE_BACKING)))
 		return -EIO;
 
+	if (!out->f_op->splice_write)
+		return -EINVAL;
+
 	ret = file_remove_privs(ctx->user_file);
 	if (ret)
 		return ret;
 
 	old_cred = override_creds(ctx->cred);
 	file_start_write(out);
-	ret = iter_file_splice_write(pipe, out, ppos, len, flags);
+	ret = out->f_op->splice_write(pipe, out, ppos, len, flags);
 	file_end_write(out);
 	revert_creds(old_cred);
 
-- 
2.18.0

Re: [PATCH 1/1] backing-file: convert to using fops->splice_write

[Amir Goldstein]

Christian,

Would you mind picking up this fix via the vfs tree?
The reason that the Fixes tag points to fuse passthrough patch is twofold:

1. fuse passthrough is a new user of backing_file_splice_write() which
    can have a fuse or overlayfs backing file with custom ->splice_write()
2. overlayfs can have a backing upper file which is a fuse passthrough
    file with a custom ->splice_write()

Thanks,
Amir.

On Mon, Jul 8, 2024 at 9:23 AM <ed.tsai@mediatek.com> wrote:
>
> From: Ed Tsai <ed.tsai@mediatek.com>
>
> Filesystems may define their own splice write. Therefore, use the file
> fops instead of invoking iter_file_splice_write() directly.
>

Fixes: 5ca73468612d ("fuse: implement splice read/write passthrough")
Reviewed-by: Amir Goldstein <amir73il@gmail.com>

> Signed-off-by: Ed Tsai <ed.tsai@mediatek.com>
> ---
>  fs/backing-file.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/backing-file.c b/fs/backing-file.c
> index afb557446c27..8860dac58c37 100644
> --- a/fs/backing-file.c
> +++ b/fs/backing-file.c
> @@ -303,13 +303,16 @@ ssize_t backing_file_splice_write(struct pipe_inode_info *pipe,
>         if (WARN_ON_ONCE(!(out->f_mode & FMODE_BACKING)))
>                 return -EIO;
>
> +       if (!out->f_op->splice_write)
> +               return -EINVAL;
> +
>         ret = file_remove_privs(ctx->user_file);
>         if (ret)
>                 return ret;
>
>         old_cred = override_creds(ctx->cred);
>         file_start_write(out);
> -       ret = iter_file_splice_write(pipe, out, ppos, len, flags);
> +       ret = out->f_op->splice_write(pipe, out, ppos, len, flags);
>         file_end_write(out);
>         revert_creds(old_cred);
>
> --
> 2.18.0
>

Re: [PATCH 1/1] backing-file: convert to using fops->splice_write

[Christian Brauner]

On Mon, 08 Jul 2024 15:22:06 +0800, ed.tsai@mediatek.com wrote:
> Filesystems may define their own splice write. Therefore, use the file
> fops instead of invoking iter_file_splice_write() directly.
> 
> 

Applied to the vfs.fixes branch of the vfs/vfs.git tree.
Patches in the vfs.fixes 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.fixes

[1/1] backing-file: convert to using fops->splice_write
      https://git.kernel.org/vfs/vfs/c/996b37da1e0f