[Virtio-fs] [PATCH v2 4/7] fuse: Add dedicated filesystem context ops for submounts

[Max Reitz]

On 04.06.21 18:11, Greg Kurz wrote:
> The creation of a submount is open-coded in fuse_dentry_automount().
> This brings a lot of complexity and we recently had to fix bugs
> because we weren't setting SB_BORN or because we were unlocking
> sb->s_umount before sb was fully configured. Most of these could
> have been avoided by using the mount API instead of open-coding.
>
> Basically, this means coming up with a proper ->get_tree()
> implementation for submounts and call vfs_get_tree(), or better
> fc_mount().
>
> The creation of the superblock for submounts is quite different from
> the root mount. Especially, it doesn't require to allocate a FUSE
> filesystem context, nor to parse parameters.
>
> Introduce a dedicated context ops for submounts to make this clear.
> This is just a placeholder for now, fuse_get_tree_submount() will
> be populated in a subsequent patch.
>
> Only visible change is that we stop allocating/freeing a useless FUSE
> filesystem context with submounts.
>
> Signed-off-by: Greg Kurz <groug at kaod.org>
> ---
>   fs/fuse/fuse_i.h    |  5 +++++
>   fs/fuse/inode.c     | 16 ++++++++++++++++
>   fs/fuse/virtio_fs.c |  3 +++
>   3 files changed, 24 insertions(+)

Reviewed-by: Max Reitz <mreitz at redhat.com>