vfs: Use sget_fc() for pseudo-filesystems

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/libfs.c

@@ -237,17 +237,11 @@ static const struct super_operations simple_super_operations = {
 	.statfs		= simple_statfs,
 };
 
-static int pseudo_fs_get_tree(struct fs_context *fc)
+static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc)
 {
 	struct pseudo_fs_context *ctx = fc->fs_private;
-	struct super_block *s;
 	struct inode *root;
 
-	s = sget_userns(fc->fs_type, NULL, set_anon_super, SB_KERNMOUNT|SB_NOUSER,
-			&init_user_ns, NULL);
-	if (IS_ERR(s))
-		return PTR_ERR(s);
-
 	s->s_maxbytes = MAX_LFS_FILESIZE;
 	s->s_blocksize = PAGE_SIZE;
 	s->s_blocksize_bits = PAGE_SHIFT;
@@ -257,7 +251,8 @@ static int pseudo_fs_get_tree(struct fs_context *fc)
 	s->s_time_gran = 1;
 	root = new_inode(s);
 	if (!root)
-		goto Enomem;
+		return -ENOMEM;
+
 	/*
 	 * since this is the first inode, make it number 1. New inodes created
 	 * after this must take care not to collide with it (by passing
@@ -268,15 +263,14 @@ static int pseudo_fs_get_tree(struct fs_context *fc)
 	root->i_atime = root->i_mtime = root->i_ctime = current_time(root);
 	s->s_root = d_make_root(root);
 	if (!s->s_root)
-		goto Enomem;
-	s->s_d_op = ctx->dops;
-	s->s_flags |= SB_ACTIVE;
-	fc->root = dget(s->s_root);
-	return 0;
-
-Enomem:
-	deactivate_locked_super(s);
 		return -ENOMEM;
+	s->s_d_op = ctx->dops;
+	return 0;
+}
+
+static int pseudo_fs_get_tree(struct fs_context *fc)
+{
+	return vfs_get_super(fc, vfs_get_independent_super, pseudo_fs_fill_super);
 }
 
 static void pseudo_fs_free(struct fs_context *fc)
@@ -303,6 +297,8 @@ struct pseudo_fs_context *init_pseudo(struct fs_context *fc,
 		ctx->magic = magic;
 		fc->fs_private = ctx;
 		fc->ops = &pseudo_fs_context_ops;
+		fc->sb_flags |= SB_NOUSER;
+		fc->global = true;
 	}
 	return ctx;
 }