Re: [PATCH RFC 2/3] fs: add vfs_cmd_create()

[Christoph Hellwig <hch@lst.de>]

On Tue, Aug 01, 2023 at 03:09:01PM +0200, Christian Brauner wrote:
> Split the steps to create a superblock into a tiny helper. This will
> make the next patch easier to follow.
> 
> Signed-off-by: Christian Brauner <brauner@kernel.org>
> ---
>  fs/fsopen.c | 45 +++++++++++++++++++++++++++++++--------------
>  1 file changed, 31 insertions(+), 14 deletions(-)
> 
> diff --git a/fs/fsopen.c b/fs/fsopen.c
> index fc9d2d9fd234..af2ff05dcee5 100644
> --- a/fs/fsopen.c
> +++ b/fs/fsopen.c
> @@ -209,6 +209,36 @@ SYSCALL_DEFINE3(fspick, int, dfd, const char __user *, path, unsigned int, flags
>  	return ret;
>  }
>  
> +static int vfs_cmd_create(struct fs_context *fc)
> +{
> +	struct super_block *sb;
> +	int ret;
> +
> +	if (fc->phase != FS_CONTEXT_CREATE_PARAMS)
> +		return -EBUSY;
> +
> +	if (!mount_capable(fc))
> +		return -EPERM;
> +
> +	fc->phase = FS_CONTEXT_CREATING;
> +
> +	ret = vfs_get_tree(fc);
> +	if (ret)
> +		return ret;

The error handling here now fails to set FS_CONTEXT_FAILED.

Also at a very minimum I'd also want a helper for the reconfigure
case to mirror this one.  But I think the whole sys_fsconfig and
vfs_fsconfig_locked combination is a complete and utter mess and
should be split into one top-level handler by cmd with a bunch of
shared helper instead of this spaghetti code.