btrfs-progs: enhance error handling of __free_extent()

check/main.c

@@ -3550,6 +3550,11 @@ static int check_root_refs(struct btrfs_root *root,
 				 */
 				if (!rec->found_root_item)
 					continue;
+				if (opt_check_repair) {
+					ret = repair_subvol_orphan_item(gfs_info, rec->objectid);
+					if (!ret)
+						continue;
+				}
 				errors++;
 				fprintf(stderr, "fs tree %llu missing orphan item\n", rec->objectid);
 			}

check/mode-common.c

@@ -1672,3 +1672,36 @@ int check_and_repair_super_num_devs(struct btrfs_fs_info *fs_info)
 	printf("Successfully reset super num devices to %u\n", found_devs);
 	return 0;
 }
+
+int repair_subvol_orphan_item(struct btrfs_fs_info *fs_info, u64 rootid)
+{
+	struct btrfs_root *tree_root = fs_info->tree_root;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_path path = { 0 };
+	int ret;
+
+	trans = btrfs_start_transaction(tree_root, 1);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		errno = -ret;
+		error_msg(ERROR_MSG_START_TRANS, "%m");
+		return ret;
+	}
+	ret = btrfs_add_orphan_item(trans, tree_root, &path, rootid);
+	btrfs_release_path(&path);
+	if (ret < 0) {
+		errno = -ret;
+		error("failed to insert orphan item for subvolume %llu: %m", rootid);
+		btrfs_abort_transaction(trans, ret);
+		btrfs_commit_transaction(trans, tree_root);
+		return ret;
+	}
+	ret = btrfs_commit_transaction(trans, tree_root);
+	if (ret < 0) {
+		errno = -ret;
+		error_msg(ERROR_MSG_COMMIT_TRANS, "%m");
+		return ret;
+	}
+	printf("Added back missing orphan item for subvolume %llu\n", rootid);
+	return 0;
+}

check/mode-common.h

@@ -197,5 +197,6 @@ int repair_dev_item_bytes_used(struct btrfs_fs_info *fs_info,
 int fill_csum_tree(struct btrfs_trans_handle *trans, bool search_fs_tree);
 
 int check_and_repair_super_num_devs(struct btrfs_fs_info *fs_info);
+int repair_subvol_orphan_item(struct btrfs_fs_info *fs_info, u64 rootid);
 
 #endif

check/mode-lowmem.c

@@ -5569,9 +5569,16 @@ static int check_btrfs_root(struct btrfs_root *root, int check_all)
 	 * If this tree is a subvolume (not a reloc tree) and has no refs, there
 	 * should be an orphan item for it, or this subvolume will never be deleted.
 	 */
-	if (btrfs_root_refs(root_item) == 0 && is_fstree(btrfs_root_id(root))) {
-		if (!has_orphan_item(root->fs_info->tree_root,
-				     btrfs_root_id(root))) {
+	if (btrfs_root_refs(root_item) == 0 && is_fstree(btrfs_root_id(root)) &&
+	    !has_orphan_item(root->fs_info->tree_root, btrfs_root_id(root))) {
+		bool repaired = false;
+
+		if (opt_check_repair) {
+			ret = repair_subvol_orphan_item(root->fs_info, btrfs_root_id(root));
+			if (!ret)
+				repaired = true;
+		}
+		if (!repaired) {
 			error("missing orphan item for root %lld", btrfs_root_id(root));
 			err |= REFERENCER_MISSING;
 		}

kernel-shared/extent-tree.c

@@ -1980,90 +1980,86 @@ static int __free_extent(struct btrfs_trans_handle *trans,
 				    bytenr, num_bytes, parent,
 				    root_objectid, owner_objectid,
 				    owner_offset);
-	if (ret == 0) {
-		extent_slot = path->slots[0];
-		while (extent_slot >= 0) {
-			btrfs_item_key_to_cpu(path->nodes[0], &key,
-					      extent_slot);
-			if (key.objectid != bytenr)
-				break;
-			if (key.type == BTRFS_EXTENT_ITEM_KEY &&
-			    key.offset == num_bytes) {
-				found_extent = 1;
-				break;
-			}
-			if (key.type == BTRFS_METADATA_ITEM_KEY &&
-			    key.offset == owner_objectid) {
-				found_extent = 1;
-				break;
-			}
-			if (path->slots[0] - extent_slot > 5)
-				break;
-			extent_slot--;
+	if (ret) {
+		error("unable to find ref byte nr %llu parent %llu root %llu  owner %llu offset %llu ret %d\n",
+		       bytenr, parent, root_objectid, owner_objectid,
+		       owner_offset, ret);
+		if (path->nodes[0]) {
+			printf("path->slots[0]: %d path->nodes[0]:\n", path->slots[0]);
+			btrfs_print_leaf(path->nodes[0]);
 		}
-		if (!found_extent) {
-			BUG_ON(iref);
-			ret = remove_extent_backref(trans, extent_root, path,
-						    NULL, refs_to_drop,
-						    is_data);
-			BUG_ON(ret);
-			btrfs_release_path(path);
+		ret = -EIO;
+		goto fail;
+	}
+	extent_slot = path->slots[0];
+	while (extent_slot >= 0) {
+		btrfs_item_key_to_cpu(path->nodes[0], &key,
+				      extent_slot);
+		if (key.objectid != bytenr)
+			break;
+		if (key.type == BTRFS_EXTENT_ITEM_KEY &&
+		    key.offset == num_bytes) {
+			found_extent = 1;
+			break;
+		}
+		if (key.type == BTRFS_METADATA_ITEM_KEY &&
+		    key.offset == owner_objectid) {
+			found_extent = 1;
+			break;
+		}
+		if (path->slots[0] - extent_slot > 5)
+			break;
+		extent_slot--;
+	}
+	if (!found_extent) {
+		BUG_ON(iref);
+		ret = remove_extent_backref(trans, extent_root, path,
+					    NULL, refs_to_drop,
+					    is_data);
+		BUG_ON(ret);
+		btrfs_release_path(path);
 
-			key.objectid = bytenr;
+		key.objectid = bytenr;
 
-			if (skinny_metadata) {
-				key.type = BTRFS_METADATA_ITEM_KEY;
-				key.offset = owner_objectid;
-			} else {
-				key.type = BTRFS_EXTENT_ITEM_KEY;
-				key.offset = num_bytes;
-			}
+		if (skinny_metadata) {
+			key.type = BTRFS_METADATA_ITEM_KEY;
+			key.offset = owner_objectid;
+		} else {
+			key.type = BTRFS_EXTENT_ITEM_KEY;
+			key.offset = num_bytes;
+		}
 
+		ret = btrfs_search_slot(trans, extent_root,
+					&key, path, -1, 1);
+		if (ret > 0 && skinny_metadata && path->slots[0]) {
+			path->slots[0]--;
+			btrfs_item_key_to_cpu(path->nodes[0],
+					      &key,
+					      path->slots[0]);
+			if (key.objectid == bytenr &&
+			    key.type == BTRFS_EXTENT_ITEM_KEY &&
+			    key.offset == num_bytes)
+				ret = 0;
+		}
+
+		if (ret > 0 && skinny_metadata) {
+			skinny_metadata = 0;
+			btrfs_release_path(path);
+			key.type = BTRFS_EXTENT_ITEM_KEY;
+			key.offset = num_bytes;
 			ret = btrfs_search_slot(trans, extent_root,
 						&key, path, -1, 1);
-			if (ret > 0 && skinny_metadata && path->slots[0]) {
-				path->slots[0]--;
-				btrfs_item_key_to_cpu(path->nodes[0],
-						      &key,
-						      path->slots[0]);
-				if (key.objectid == bytenr &&
-				    key.type == BTRFS_EXTENT_ITEM_KEY &&
-				    key.offset == num_bytes)
-					ret = 0;
-			}
-
-			if (ret > 0 && skinny_metadata) {
-				skinny_metadata = 0;
-				btrfs_release_path(path);
-				key.type = BTRFS_EXTENT_ITEM_KEY;
-				key.offset = num_bytes;
-				ret = btrfs_search_slot(trans, extent_root,
-							&key, path, -1, 1);
-			}
+		}
 
-			if (ret) {
-				printk(KERN_ERR "umm, got %d back from search"
-				       ", was looking for %llu\n", ret,
-				       (unsigned long long)bytenr);
-				btrfs_print_leaf(path->nodes[0]);
-			}
-			BUG_ON(ret);
-			extent_slot = path->slots[0];
+		if (ret) {
+			printk(KERN_ERR "umm, got %d back from search"
+			       ", was looking for %llu\n", ret,
+			       (unsigned long long)bytenr);
+			btrfs_print_leaf(path->nodes[0]);
 		}
-	} else {
-		printk(KERN_ERR "btrfs unable to find ref byte nr %llu "
-		       "parent %llu root %llu  owner %llu offset %llu\n",
-		       (unsigned long long)bytenr,
-		       (unsigned long long)parent,
-		       (unsigned long long)root_objectid,
-		       (unsigned long long)owner_objectid,
-		       (unsigned long long)owner_offset);
-		printf("path->slots[0]: %d path->nodes[0]:\n", path->slots[0]);
-		btrfs_print_leaf(path->nodes[0]);
-		ret = -EIO;
-		goto fail;
+		BUG_ON(ret);
+		extent_slot = path->slots[0];
 	}
-
 	leaf = path->nodes[0];
 	item_size = btrfs_item_size(leaf, extent_slot);
 	if (item_size < sizeof(*ei)) {