vfs: simple_set_mnt() should return void

simple_set_mnt() is defined as returning 'int' but always returns 0.
Callers assume simple_set_mnt() never fails and don't properly cleanup if
it were to _ever_ fail.  For instance, get_sb_single() and get_sb_nodev()
should:

        up_write(sb->s_unmount);
        deactivate_super(sb);

if simple_set_mnt() fails.

Since simple_set_mnt() never fails, would be cleaner if it did not
return anything.

[[email protected]: fix build]
Signed-off-by: Sukadev Bhattiprolu <[email protected]>
Acked-by: Serge Hallyn <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Al Viro <[email protected]>

drivers/mtd/mtdsuper.c

@@ -81,13 +81,16 @@ static int get_sb_mtd_aux(struct file_system_type *fs_type, int flags,
 
 	/* go */
 	sb->s_flags |= MS_ACTIVE;
-	return simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+
+	return 0;
 
 	/* new mountpoint for an already mounted superblock */
 already_mounted:
 	DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
 	      mtd->index, mtd->name);
-	ret = simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+	ret = 0;
 	goto out_put;
 
 out_error:

fs/9p/vfs_super.c

@@ -168,8 +168,9 @@ static int v9fs_get_sb(struct file_system_type *fs_type, int flags,
 	p9stat_free(st);
 	kfree(st);
 
-P9_DPRINTK(P9_DEBUG_VFS, " return simple set mount\n");
-	return simple_set_mnt(mnt, sb);
+P9_DPRINTK(P9_DEBUG_VFS, " simple set mount, return 0\n");
+	simple_set_mnt(mnt, sb);
+	return 0;
 
 release_sb:
 	if (sb) {

fs/cifs/cifsfs.c

@@ -606,7 +606,8 @@ cifs_get_sb(struct file_system_type *fs_type,
 		return rc;
 	}
 	sb->s_flags |= MS_ACTIVE;
-	return simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+	return 0;
 }
 
 static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,

fs/devpts/inode.c

@@ -454,7 +454,8 @@ static int get_init_pts_sb(struct file_system_type *fs_type, int flags,
 		s->s_flags |= MS_ACTIVE;
 	}
 	do_remount_sb(s, flags, data, 0);
-	return simple_set_mnt(mnt, s);
+	simple_set_mnt(mnt, s);
+	return 0;
 }
 
 /*

fs/libfs.c

@@ -242,7 +242,8 @@ int get_sb_pseudo(struct file_system_type *fs_type, char *name,
 	d_instantiate(dentry, root);
 	s->s_root = dentry;
 	s->s_flags |= MS_ACTIVE;
-	return simple_set_mnt(mnt, s);
+	simple_set_mnt(mnt, s);
+	return 0;
 
 Enomem:
 	up_write(&s->s_umount);

fs/namespace.c

@@ -397,11 +397,10 @@ static void __mnt_unmake_readonly(struct vfsmount *mnt)
 	spin_unlock(&vfsmount_lock);
 }
 
-int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
+void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
 {
 	mnt->mnt_sb = sb;
 	mnt->mnt_root = dget(sb->s_root);
-	return 0;
 }
 
 EXPORT_SYMBOL(simple_set_mnt);

fs/proc/root.c

@@ -83,7 +83,8 @@ static int proc_get_sb(struct file_system_type *fs_type,
 		ns->proc_mnt = mnt;
 	}
 
-	return simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+	return 0;
 }
 
 static void proc_kill_sb(struct super_block *sb)

fs/super.c

@@ -831,7 +831,8 @@ int get_sb_bdev(struct file_system_type *fs_type,
 		bdev->bd_super = s;
 	}
 
-	return simple_set_mnt(mnt, s);
+	simple_set_mnt(mnt, s);
+	return 0;
 
 error_s:
 	error = PTR_ERR(s);
@@ -877,7 +878,8 @@ int get_sb_nodev(struct file_system_type *fs_type,
 		return error;
 	}
 	s->s_flags |= MS_ACTIVE;
-	return simple_set_mnt(mnt, s);
+	simple_set_mnt(mnt, s);
+	return 0;
 }
 
 EXPORT_SYMBOL(get_sb_nodev);
@@ -909,7 +911,8 @@ int get_sb_single(struct file_system_type *fs_type,
 		s->s_flags |= MS_ACTIVE;
 	}
 	do_remount_sb(s, flags, data, 0);
-	return simple_set_mnt(mnt, s);
+	simple_set_mnt(mnt, s);
+	return 0;
 }
 
 EXPORT_SYMBOL(get_sb_single);

fs/ubifs/super.c

@@ -2034,7 +2034,8 @@ static int ubifs_get_sb(struct file_system_type *fs_type, int flags,
 	/* 'fill_super()' opens ubi again so we must close it here */
 	ubi_close_volume(ubi);
 
-	return simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+	return 0;
 
 out_deact:
 	up_write(&sb->s_umount);

include/linux/fs.h

@@ -1719,7 +1719,7 @@ struct super_block *sget(struct file_system_type *type,
 extern int get_sb_pseudo(struct file_system_type *, char *,
 	const struct super_operations *ops, unsigned long,
 	struct vfsmount *mnt);
-extern int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb);
+extern void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb);
 int __put_super_and_need_restart(struct super_block *sb);
 
 /* Alas, no aliases. Too much hassle with bringing module.h everywhere */

kernel/cgroup.c

@@ -1071,7 +1071,8 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
 		mutex_unlock(&cgroup_mutex);
 	}
 
-	return simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+	return 0;
 
  free_cg_links:
 	free_cg_links(&tmp_cg_links);