vfs: Convert pipe to use the new mount API

Convert the pipe filesystem to the new internal mount API as the old
one will be obsoleted and removed.  This allows greater flexibility in
communication of mount parameters between userspace, the VFS and the
filesystem.

See Documentation/filesystems/mount_api.txt for more information.
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/pipe.c

@@ -14,6 +14,7 @@
 #include <linux/fs.h>
 #include <linux/log2.h>
 #include <linux/mount.h>
+#include <linux/pseudo_fs.h>
 #include <linux/magic.h>
 #include <linux/pipe_fs_i.h>
 #include <linux/uio.h>
@@ -1182,16 +1183,20 @@ static const struct super_operations pipefs_ops = {
  * any operations on the root directory. However, we need a non-trivial
  * d_name - pipe: will go nicely and kill the special-casing in procfs.
  */
-static struct dentry *pipefs_mount(struct file_system_type *fs_type,
-			 int flags, const char *dev_name, void *data)
+
+static int pipefs_init_fs_context(struct fs_context *fc)
 {
-	return mount_pseudo(fs_type, &pipefs_ops,
-			&pipefs_dentry_operations, PIPEFS_MAGIC);
+	struct pseudo_fs_context *ctx = init_pseudo(fc, PIPEFS_MAGIC);
+	if (!ctx)
+		return -ENOMEM;
+	ctx->ops = &pipefs_ops;
+	ctx->dops = &pipefs_dentry_operations;
+	return 0;
 }
 
 static struct file_system_type pipe_fs_type = {
 	.name		= "pipefs",
-	.mount		= pipefs_mount,
+	.init_fs_context = pipefs_init_fs_context,
 	.kill_sb	= kill_anon_super,
 };