vfs: Convert zsmalloc to use the new mount API

Convert the zsmalloc 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: Minchan Kim <minchan@kernel.org>
cc: Nitin Gupta <ngupta@vflare.org>
cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
cc: linux-mm@kvack.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

mm/zsmalloc.c

@@ -52,6 +52,7 @@
 #include <linux/zsmalloc.h>
 #include <linux/zpool.h>
 #include <linux/mount.h>
+#include <linux/pseudo_fs.h>
 #include <linux/migrate.h>
 #include <linux/pagemap.h>
 #include <linux/fs.h>
@@ -1814,15 +1815,14 @@ static void lock_zspage(struct zspage *zspage)
 	} while ((page = get_next_page(page)) != NULL);
 }
 
-static struct dentry *zs_mount(struct file_system_type *fs_type,
-				int flags, const char *dev_name, void *data)
+static int zs_init_fs_context(struct fs_context *fc)
 {
-	return mount_pseudo(fs_type, NULL, NULL, ZSMALLOC_MAGIC);
+	return init_pseudo(fc, ZSMALLOC_MAGIC) ? 0 : -ENOMEM;
 }
 
 static struct file_system_type zsmalloc_fs = {
 	.name		= "zsmalloc",
-	.mount		= zs_mount,
+	.init_fs_context = zs_init_fs_context,
 	.kill_sb	= kill_anon_super,
 };