fuse: Fix crash if superblock of submount gets killed early

As soon as fuse_dentry_automount() does up_write(&sb->s_umount), the
superblock can theoretically be killed. If this happens before the
submount was added to the &fc->mounts list, fuse_mount_remove() later
crashes in list_del_init() because it assumes the submount to be
already there.

Add the submount before dropping sb->s_umount to fix the inconsistency.
It is okay to nest fc->killsb under sb->s_umount, we already do this
on the ->kill_sb() path.

Signed-off-by: Greg Kurz <[email protected]>
Fixes: bf109c64040f ("fuse: implement crossmounts")
Cc: [email protected] # v5.10+
Reviewed-by: Max Reitz <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>

0 files changed, 0 insertions, 0 deletions