btrfs-progs: subvol: change set-default to also accept path

[platform/upstream/btrfs-progs.git] / cmds-subvolume.c

diff --git a/cmds-subvolume.c b/cmds-subvolume.c
index e7caa05..dc626a6 100644 (file)
--- a/cmds-subvolume.c
+++ b/cmds-subvolume.c
@@ -858,8 +858,11 @@ out:
 }
 
 static const char * const cmd_subvol_set_default_usage[] = {
+       "btrfs subvolume set-default <subvolume>\n"
        "btrfs subvolume set-default <subvolid> <path>",
-       "Set the default subvolume of a filesystem",
+       "Set the default subvolume of the filesystem mounted as default.",
+       "The subvolume can be specified by its path,",
+       "or the pair of subvolume id and path to the filesystem.",
        NULL
 };
 
@@ -873,17 +876,43 @@ static int cmd_subvol_set_default(int argc, char **argv)
 
        clean_args_no_options(argc, argv, cmd_subvol_set_default_usage);
 
-       if (check_argc_exact(argc - optind, 2))
+       if (check_argc_min(argc - optind, 1) ||
+                       check_argc_max(argc - optind, 2))
                usage(cmd_subvol_set_default_usage);
 
-       subvolid = argv[optind];
-       path = argv[optind + 1];
+       if (argc - optind == 1) {
+               /* path to the subvolume is specified */
+               path = argv[optind];
 
-       objectid = arg_strtou64(subvolid);
+               ret = test_issubvolume(path);
+               if (ret < 0) {
+                       error("stat error: %s", strerror(-ret));
+                       return 1;
+               } else if (!ret) {
+                       error("'%s' is not a subvolume", path);
+                       return 1;
+               }
 
-       fd = btrfs_open_dir(path, &dirstream, 1);
-       if (fd < 0)
-               return 1;
+               fd = btrfs_open_dir(path, &dirstream, 1);
+               if (fd < 0)
+                       return 1;
+
+               ret = lookup_path_rootid(fd, &objectid);
+               if (ret) {
+                       error("unable to get subvol id: %s", strerror(-ret));
+                       close_file_or_dir(fd, dirstream);
+                       return 1;
+               }
+       } else {
+               /* subvol id and path to the filesystem are specified */
+               subvolid = argv[optind];
+               path = argv[optind + 1];
+               objectid = arg_strtou64(subvolid);
+
+               fd = btrfs_open_dir(path, &dirstream, 1);
+               if (fd < 0)
+                       return 1;
+       }
 
        ret = ioctl(fd, BTRFS_IOC_DEFAULT_SUBVOL, &objectid);
        e = errno;