Btrfs-progs: add an option for specifying the root to restore

If the normal fs tree is hosed and the user has multiple subvolumes it's handy
to be able to specify just one of the subvolumes to restore.  It's also handy if
a user only wants to restore say /home instead of his entire disk.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

diff --git a/cmds-restore.c b/cmds-restore.c
index 4a14f93..467e5ef 100644 (file)
--- a/cmds-restore.c
+++ b/cmds-restore.c
@@ -773,13 +773,14 @@ int cmd_restore(int argc, char **argv)
        char dir_name[128];
        u64 tree_location = 0;
        u64 fs_location = 0;
+       u64 root_objectid = 0;
        int len;
        int ret;
        int opt;
        int super_mirror = 0;
        int find_dir = 0;
 
-       while ((opt = getopt(argc, argv, "sviot:u:df:")) != -1) {
+       while ((opt = getopt(argc, argv, "sviot:u:df:r:")) != -1) {
                switch (opt) {
                        case 's':
                                get_snaps = 1;
@@ -822,6 +823,14 @@ int cmd_restore(int argc, char **argv)
                        case 'd':
                                find_dir = 1;
                                break;
+                       case 'r':
+                               errno = 0;
+                               root_objectid = (u64)strtoll(optarg, NULL, 10);
+                               if (errno != 0) {
+                                       fprintf(stderr, "Root objectid not valid\n");
+                                       exit(1);
+                               }
+                               break;
                        default:
                                usage(cmd_restore_usage);
                }
@@ -852,8 +861,6 @@ int cmd_restore(int argc, char **argv)
                }
        }
 
-       printf("Root objectid is %Lu\n", root->objectid);
-
        memset(path_name, 0, 4096);
 
        strncpy(dir_name, argv[optind + 1], sizeof dir_name);
@@ -865,6 +872,23 @@ int cmd_restore(int argc, char **argv)
                dir_name[len] = '\0';
        }
 
+       if (root_objectid != 0) {
+               struct btrfs_root *orig_root = root;
+
+               key.objectid = root_objectid;
+               key.type = BTRFS_ROOT_ITEM_KEY;
+               key.offset = (u64)-1;
+               root = btrfs_read_fs_root(orig_root->fs_info, &key);
+               if (IS_ERR(root)) {
+                       fprintf(stderr, "Error reading root\n");
+                       root = orig_root;
+                       ret = 1;
+                       goto out;
+               }
+               key.type = 0;
+               key.offset = 0;
+       }
+
        if (find_dir) {
                ret = find_first_dir(root, &key.objectid);
                if (ret)
@@ -873,7 +897,7 @@ int cmd_restore(int argc, char **argv)
                key.objectid = BTRFS_FIRST_FREE_OBJECTID;
        }
 
-       ret = search_dir(root->fs_info->fs_root, &key, dir_name);
+       ret = search_dir(root, &key, dir_name);
 
 out:
        close_ctree(root);