vfs: Convert binfmt_misc to use the new mount API

Convert the binfmt_misc 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: Alexander Viro <viro@zeniv.linux.org.uk>
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Author: dhowells

fs/binfmt_misc.c

@@ -22,6 +22,7 @@
 #include <linux/pagemap.h>
 #include <linux/namei.h>
 #include <linux/mount.h>
+#include <linux/fs_context.h>
 #include <linux/syscalls.h>
 #include <linux/fs.h>
 #include <linux/uaccess.h>
@@ -820,7 +821,7 @@ static const struct super_operations s_ops = {
 	.evict_inode	= bm_evict_inode,
 };
 
-static int bm_fill_super(struct super_block *sb, void *data, int silent)
+static int bm_fill_super(struct super_block *sb, struct fs_context *fc)
 {
 	int err;
 	static const struct tree_descr bm_files[] = {
@@ -835,10 +836,19 @@ static int bm_fill_super(struct super_block *sb, void *data, int silent)
 	return err;
 }
 
-static struct dentry *bm_mount(struct file_system_type *fs_type,
-	int flags, const char *dev_name, void *data)
+static int bm_get_tree(struct fs_context *fc)
 {
-	return mount_single(fs_type, flags, data, bm_fill_super);
+	return get_tree_single(fc, bm_fill_super);
+}
+
+static const struct fs_context_operations bm_context_ops = {
+	.get_tree	= bm_get_tree,
+};
+
+static int bm_init_fs_context(struct fs_context *fc)
+{
+	fc->ops = &bm_context_ops;
+	return 0;
 }
 
 static struct linux_binfmt misc_format = {
@@ -849,7 +859,7 @@ static struct linux_binfmt misc_format = {
 static struct file_system_type bm_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "binfmt_misc",
-	.mount		= bm_mount,
+	.init_fs_context = bm_init_fs_context,
 	.kill_sb	= kill_litter_super,
 };
 MODULE_ALIAS_FS("binfmt_misc");