Take the completion of automount into new helper

... and shift it from namei.c to namespace.c
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/internal.h

@@ -70,6 +70,7 @@ extern void mnt_set_mountpoint(struct vfsmount *, struct dentry *,
 extern void release_mounts(struct list_head *);
 extern void umount_tree(struct vfsmount *, int, struct list_head *);
 extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int);
+extern int finish_automount(struct vfsmount *, struct path *);
 extern int do_add_mount(struct vfsmount *, struct path *, int);
 extern void mnt_clear_expiry(struct vfsmount *);
 

fs/namei.c

@@ -923,37 +923,13 @@ static int follow_automount(struct path *path, unsigned flags,
 	if (!mnt) /* mount collision */
 		return 0;
 
-	/* The new mount record should have at least 2 refs to prevent it being
-	 * expired before we get a chance to add it
-	 */
-	BUG_ON(mnt_get_count(mnt) < 2);
-
-	if (mnt->mnt_sb == path->mnt->mnt_sb &&
-	    mnt->mnt_root == path->dentry) {
-		mnt_clear_expiry(mnt);
-		mntput(mnt);
-		mntput(mnt);
-		return -ELOOP;
-	}
+	err = finish_automount(mnt, path);
 
-	/* We need to add the mountpoint to the parent.  The filesystem may
-	 * have placed it on an expiry list, and so we need to make sure it
-	 * won't be expired under us if do_add_mount() fails (do_add_mount()
-	 * will eat a reference unconditionally).
-	 */
-	mntget(mnt);
-	err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
 	switch (err) {
 	case -EBUSY:
 		/* Someone else made a mount here whilst we were busy */
-		err = 0;
-	default:
-		mnt_clear_expiry(mnt);
-		mntput(mnt);
-		mntput(mnt);
-		return err;
+		return 0;
 	case 0:
-		mntput(mnt);
 		dput(path->dentry);
 		if (*need_mntput)
 			mntput(path->mnt);
@@ -961,7 +937,10 @@ static int follow_automount(struct path *path, unsigned flags,
 		path->dentry = dget(mnt->mnt_root);
 		*need_mntput = true;
 		return 0;
+	default:
+		return err;
 	}
+
 }
 
 /*

fs/namespace.c

@@ -1895,6 +1895,39 @@ static int do_new_mount(struct path *path, char *type, int flags,
 	return do_add_mount(mnt, path, mnt_flags);
 }
 
+int finish_automount(struct vfsmount *m, struct path *path)
+{
+	int err;
+	/* The new mount record should have at least 2 refs to prevent it being
+	 * expired before we get a chance to add it
+	 */
+	BUG_ON(mnt_get_count(m) < 2);
+
+	if (m->mnt_sb == path->mnt->mnt_sb &&
+	    m->mnt_root == path->dentry) {
+		mnt_clear_expiry(m);
+		mntput(m);
+		mntput(m);
+		return -ELOOP;
+	}
+
+	/* We need to add the mountpoint to the parent.  The filesystem may
+	 * have placed it on an expiry list, and so we need to make sure it
+	 * won't be expired under us if do_add_mount() fails (do_add_mount()
+	 * will eat a reference unconditionally).
+	 */
+	mntget(m);
+	err = do_add_mount(m, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
+	if (err) {
+		mnt_clear_expiry(m);
+		mntput(m);
+		mntput(m);
+	} else {
+		mntput(m);
+	}
+	return err;
+}
+
 /*
  * add a mount into a namespace's mount tree
  * - this unconditionally eats one of the caller's references to newmnt.