Btrfs-progs: give restore a list roots option

Since restore has the ability to open really really screwed up file systems, add
a list roots option to it so we can still get the contents of the tree root on a
horribly broken fs.  Thanks,

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

diff --git a/cmds-restore.c b/cmds-restore.c
index e71a28f..c75e187 100644 (file)
--- a/cmds-restore.c
+++ b/cmds-restore.c
@@ -770,9 +770,70 @@ next:
        return 0;
 }
 
-static struct btrfs_root *open_fs(const char *dev, u64 root_location, int super_mirror)
+static int do_list_roots(struct btrfs_root *root)
 {
-       struct btrfs_root *root;
+       struct btrfs_key key;
+       struct btrfs_key found_key;
+       struct btrfs_disk_key disk_key;
+       struct btrfs_path *path;
+       struct extent_buffer *leaf;
+       struct btrfs_root_item ri;
+       unsigned long offset;
+       int slot;
+       int ret;
+
+       root = root->fs_info->tree_root;
+       path = btrfs_alloc_path();
+       if (!path) {
+               fprintf(stderr, "Failed to alloc path\n");
+               return -1;
+       }
+
+       key.offset = 0;
+       key.objectid = 0;
+       key.type = BTRFS_ROOT_ITEM_KEY;
+
+       ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+       if (ret < 0) {
+               fprintf(stderr, "Failed to do search %d\n", ret);
+               btrfs_free_path(path);
+               return -1;
+       }
+
+       while (1) {
+               leaf = path->nodes[0];
+               slot = path->slots[0];
+               if (slot >= btrfs_header_nritems(leaf)) {
+                       ret = btrfs_next_leaf(root, path);
+                       if (ret)
+                               break;
+                       leaf = path->nodes[0];
+                       slot = path->slots[0];
+               }
+               btrfs_item_key(leaf, &disk_key, slot);
+               btrfs_disk_key_to_cpu(&found_key, &disk_key);
+               if (btrfs_key_type(&found_key) != BTRFS_ROOT_ITEM_KEY) {
+                       path->slots[0]++;
+                       continue;
+               }
+
+               offset = btrfs_item_ptr_offset(leaf, slot);
+               read_extent_buffer(leaf, &ri, offset, sizeof(ri));
+               printf(" tree ");
+               btrfs_print_key(&disk_key);
+               printf(" %Lu level %d\n", btrfs_root_bytenr(&ri),
+                      btrfs_root_level(&ri));
+               path->slots[0]++;
+       }
+       btrfs_free_path(path);
+
+       return 0;
+}
+
+static struct btrfs_root *open_fs(const char *dev, u64 root_location,
+                                 int super_mirror, int list_roots)
+{
+       struct btrfs_root *root = NULL;
        u64 bytenr;
        int i;
 
@@ -780,11 +841,19 @@ static struct btrfs_root *open_fs(const char *dev, u64 root_location, int super_
                bytenr = btrfs_sb_offset(i);
                root = open_ctree_recovery(dev, bytenr, root_location);
                if (root)
-                       return root;
+                       break;
                fprintf(stderr, "Could not open root, trying backup super\n");
        }
 
-       return NULL;
+       if (root && list_roots) {
+               int ret = do_list_roots(root);
+               if (ret) {
+                       close_ctree(root);
+                       root = NULL;
+               }
+       }
+
+       return root;
 }
 
 static int find_first_dir(struct btrfs_root *root, u64 *objectid)
@@ -875,8 +944,9 @@ int cmd_restore(int argc, char **argv)
        int opt;
        int super_mirror = 0;
        int find_dir = 0;
+       int list_roots = 0;
 
-       while ((opt = getopt(argc, argv, "sviot:u:df:r:")) != -1) {
+       while ((opt = getopt(argc, argv, "sviot:u:df:r:l")) != -1) {
                switch (opt) {
                        case 's':
                                get_snaps = 1;
@@ -927,12 +997,17 @@ int cmd_restore(int argc, char **argv)
                                        exit(1);
                                }
                                break;
+                       case 'l':
+                               list_roots = 1;
+                               break;
                        default:
                                usage(cmd_restore_usage);
                }
        }
 
-       if (optind + 1 >= argc)
+       if (!list_roots && optind + 1 >= argc)
+               usage(cmd_restore_usage);
+       else if (list_roots && optind >= argc)
                usage(cmd_restore_usage);
 
        if ((ret = check_mounted(argv[optind])) < 0) {
@@ -944,10 +1019,13 @@ int cmd_restore(int argc, char **argv)
                return 1;
        }
 
-       root = open_fs(argv[optind], tree_location, super_mirror);
+       root = open_fs(argv[optind], tree_location, super_mirror, list_roots);
        if (root == NULL)
                return 1;
 
+       if (list_roots)
+               goto out;
+
        if (fs_location != 0) {
                free_extent_buffer(root->node);
                root->node = read_tree_block(root, fs_location, 4096, 0);