btrfs-progs: Allow debug-tree to be executed on regular file.

The commit 1bad43fbe0 ("btrfs-progs: refine btrfs-debug-tree error
prompt when a mount point given")
add judgement on btrfs-debug-tree to restrict only block device to be
executed on, but the command can also be used on regular file, so add
regular file support for the judgement.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

btrfs-debug-tree.c

@@ -180,8 +180,9 @@ int main(int ac, char **av)
 		print_usage();
 
 	ret = check_arg_type(av[optind]);
-	if (ret != BTRFS_ARG_BLKDEV) {
-		fprintf(stderr, "'%s' is not a block device\n", av[optind]);
+	if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
+		fprintf(stderr, "'%s' is not a block device or regular file\n",
+			av[optind]);
 		exit(1);
 	}
 

utils.c

@@ -854,13 +854,23 @@ int is_mount_point(const char *path)
 	return ret;
 }
 
+static int is_reg_file(const char *path)
+{
+	struct stat statbuf;
+
+	if (stat(path, &statbuf) < 0)
+		return -errno;
+	return S_ISREG(statbuf.st_mode);
+}
+
 /*
  * This function checks if the given input parameter is
  * an uuid or a path
- * return -1: some error in the given input
- * return 0: unknow input
- * return 1: given input is uuid
- * return 2: given input is path
+ * return <0 : some error in the given input
+ * return BTRFS_ARG_UNKNOWN:	unknown input
+ * return BTRFS_ARG_UUID:	given input is uuid
+ * return BTRFS_ARG_MNTPOINT:	given input is path
+ * return BTRFS_ARG_REG:	given input is regular file
  */
 int check_arg_type(const char *input)
 {
@@ -877,6 +887,9 @@ int check_arg_type(const char *input)
 		if (is_mount_point(path) == 1)
 			return BTRFS_ARG_MNTPOINT;
 
+		if (is_reg_file(path))
+			return BTRFS_ARG_REG;
+
 		return BTRFS_ARG_UNKNOWN;
 	}
 

utils.h

@@ -35,6 +35,7 @@
 #define BTRFS_ARG_MNTPOINT	1
 #define BTRFS_ARG_UUID		2
 #define BTRFS_ARG_BLKDEV	3
+#define BTRFS_ARG_REG		4
 
 #define BTRFS_UUID_UNPARSED_SIZE	37