Btrfs: Free correct pointer after using strsep

We must save and free the original kstrdup()'ed pointer
because strsep() modifies its first argument.
Signed-off-by: Tero Roponen <tero.roponen@gmail.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>

fs/btrfs/super.c

@@ -277,7 +277,7 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags,
 		struct btrfs_fs_devices **fs_devices)
 {
 	substring_t args[MAX_OPT_ARGS];
-	char *opts, *p;
+	char *opts, *orig, *p;
 	int error = 0;
 	int intarg;
 
@@ -291,6 +291,7 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags,
 	opts = kstrdup(options, GFP_KERNEL);
 	if (!opts)
 		return -ENOMEM;
+	orig = opts;
 
 	while ((p = strsep(&opts, ",")) != NULL) {
 		int token;
@@ -326,7 +327,7 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags,
 	}
 
  out_free_opts:
-	kfree(opts);
+	kfree(orig);
  out:
 	/*
 	 * If no subvolume name is specified we use the default one.  Allocate