saner calling conventions for ->d_automount()

Currently the calling conventions for ->d_automount() instances have
an odd wart - returned new mount to be attached is expected to have
refcount 2.

That kludge is intended to make sure that mark_mounts_for_expiry() called
before we get around to attaching that new mount to the tree won't decide
to take it out.  finish_automount() drops the extra reference after it's
done with attaching mount to the tree - or drops the reference twice in
case of error.  ->d_automount() instances have rather counterintuitive
boilerplate in them.

There's a much simpler approach: have mark_mounts_for_expiry() skip the
mounts that are yet to be mounted.  And to hell with grabbing/dropping
those extra references.  Makes for simpler correctness analysis, at that...

Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Acked-by: David Howells <dhowells@redhat.com>
Tested-by: David Howells <dhowells@redhat.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 0 insertions, 3 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 83ac192e7fdd..05d8584fd3b9 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -319,9 +319,6 @@ static struct vfsmount *fuse_dentry_automount(struct path *path)
 
 	/* Create the submount */
 	mnt = fc_mount(fsc);
-	if (!IS_ERR(mnt))
-		mntget(mnt);
-
 	put_fs_context(fsc);
 	return mnt;
 }