+/*
+ * Check backrefs of a tree block given by @bytenr or @eb.
+ *
+ * @root: the root containing the @bytenr or @eb
+ * @eb: tree block extent buffer, can be NULL
+ * @bytenr: bytenr of the tree block to search
+ * @level: tree level of the tree block
+ * @owner: owner of the tree block
+ *
+ * Return >0 for any error found and output error message
+ * Return 0 for no error found
+ */
+static int check_tree_block_ref(struct btrfs_root *root,
+ struct extent_buffer *eb, u64 bytenr,
+ int level, u64 owner)
+{
+ struct btrfs_key key;
+ struct btrfs_root *extent_root = root->fs_info->extent_root;
+ struct btrfs_path path;
+ struct btrfs_extent_item *ei;
+ struct btrfs_extent_inline_ref *iref;
+ struct extent_buffer *leaf;
+ unsigned long end;
+ unsigned long ptr;
+ int slot;
+ int skinny_level;
+ int type;
+ u32 nodesize = root->nodesize;
+ u32 item_size;
+ u64 offset;
+ int found_ref = 0;
+ int err = 0;
+ int ret;
+
+ btrfs_init_path(&path);
+ key.objectid = bytenr;
+ if (btrfs_fs_incompat(root->fs_info,
+ BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA))
+ key.type = BTRFS_METADATA_ITEM_KEY;
+ else
+ key.type = BTRFS_EXTENT_ITEM_KEY;
+ key.offset = (u64)-1;
+
+ /* Search for the backref in extent tree */
+ ret = btrfs_search_slot(NULL, extent_root, &key, &path, 0, 0);
+ if (ret < 0) {
+ err |= BACKREF_MISSING;
+ goto out;
+ }
+ ret = btrfs_previous_extent_item(extent_root, &path, bytenr);
+ if (ret) {
+ err |= BACKREF_MISSING;
+ goto out;
+ }
+
+ leaf = path.nodes[0];
+ slot = path.slots[0];
+ btrfs_item_key_to_cpu(leaf, &key, slot);
+
+ ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
+
+ if (key.type == BTRFS_METADATA_ITEM_KEY) {
+ skinny_level = (int)key.offset;
+ iref = (struct btrfs_extent_inline_ref *)(ei + 1);
+ } else {
+ struct btrfs_tree_block_info *info;
+
+ info = (struct btrfs_tree_block_info *)(ei + 1);
+ skinny_level = btrfs_tree_block_level(leaf, info);
+ iref = (struct btrfs_extent_inline_ref *)(info + 1);
+ }
+
+ if (eb) {
+ u64 header_gen;
+ u64 extent_gen;
+
+ if (!(btrfs_extent_flags(leaf, ei) &
+ BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
+ error(
+ "extent[%llu %u] backref type mismatch, missing bit: %llx",
+ key.objectid, nodesize,
+ BTRFS_EXTENT_FLAG_TREE_BLOCK);
+ err = BACKREF_MISMATCH;
+ }
+ header_gen = btrfs_header_generation(eb);
+ extent_gen = btrfs_extent_generation(leaf, ei);
+ if (header_gen != extent_gen) {
+ error(
+ "extent[%llu %u] backref generation mismatch, wanted: %llu, have: %llu",
+ key.objectid, nodesize, header_gen,
+ extent_gen);
+ err = BACKREF_MISMATCH;
+ }
+ if (level != skinny_level) {
+ error(
+ "extent[%llu %u] level mismatch, wanted: %u, have: %u",
+ key.objectid, nodesize, level, skinny_level);
+ err = BACKREF_MISMATCH;
+ }
+ if (!is_fstree(owner) && btrfs_extent_refs(leaf, ei) != 1) {
+ error(
+ "extent[%llu %u] is referred by other roots than %llu",
+ key.objectid, nodesize, root->objectid);
+ err = BACKREF_MISMATCH;
+ }
+ }
+
+ /*
+ * Iterate the extent/metadata item to find the exact backref
+ */
+ item_size = btrfs_item_size_nr(leaf, slot);
+ ptr = (unsigned long)iref;
+ end = (unsigned long)ei + item_size;
+ while (ptr < end) {
+ iref = (struct btrfs_extent_inline_ref *)ptr;
+ type = btrfs_extent_inline_ref_type(leaf, iref);
+ offset = btrfs_extent_inline_ref_offset(leaf, iref);
+
+ if (type == BTRFS_TREE_BLOCK_REF_KEY &&
+ (offset == root->objectid || offset == owner)) {
+ found_ref = 1;
+ } else if (type == BTRFS_SHARED_BLOCK_REF_KEY) {
+ /* Check if the backref points to valid referencer */
+ found_ref = !check_tree_block_ref(root, NULL, offset,
+ level + 1, owner);
+ }
+
+ if (found_ref)
+ break;
+ ptr += btrfs_extent_inline_ref_size(type);
+ }
+
+ /*
+ * Inlined extent item doesn't have what we need, check
+ * TREE_BLOCK_REF_KEY
+ */
+ if (!found_ref) {
+ btrfs_release_path(&path);
+ key.objectid = bytenr;
+ key.type = BTRFS_TREE_BLOCK_REF_KEY;
+ key.offset = root->objectid;
+
+ ret = btrfs_search_slot(NULL, extent_root, &key, &path, 0, 0);
+ if (!ret)
+ found_ref = 1;
+ }
+ if (!found_ref)
+ err |= BACKREF_MISSING;
+out:
+ btrfs_release_path(&path);
+ if (eb && (err & BACKREF_MISSING))
+ error("extent[%llu %u] backref lost (owner: %llu, level: %u)",
+ bytenr, nodesize, owner, level);
+ return err;
+}
+
+/*
+ * Check EXTENT_DATA item, mainly for its dbackref in extent tree
+ *
+ * Return >0 any error found and output error message
+ * Return 0 for no error found
+ */
+static int check_extent_data_item(struct btrfs_root *root,
+ struct extent_buffer *eb, int slot)
+{
+ struct btrfs_file_extent_item *fi;
+ struct btrfs_path path;
+ struct btrfs_root *extent_root = root->fs_info->extent_root;
+ struct btrfs_key fi_key;
+ struct btrfs_key dbref_key;
+ struct extent_buffer *leaf;
+ struct btrfs_extent_item *ei;
+ struct btrfs_extent_inline_ref *iref;
+ struct btrfs_extent_data_ref *dref;
+ u64 owner;
+ u64 file_extent_gen;
+ u64 disk_bytenr;
+ u64 disk_num_bytes;
+ u64 extent_num_bytes;
+ u64 extent_flags;
+ u64 extent_gen;
+ u32 item_size;
+ unsigned long end;
+ unsigned long ptr;
+ int type;
+ u64 ref_root;
+ int found_dbackref = 0;
+ int err = 0;
+ int ret;
+
+ btrfs_item_key_to_cpu(eb, &fi_key, slot);
+ fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
+ file_extent_gen = btrfs_file_extent_generation(eb, fi);
+
+ /* Nothing to check for hole and inline data extents */
+ if (btrfs_file_extent_type(eb, fi) == BTRFS_FILE_EXTENT_INLINE ||
+ btrfs_file_extent_disk_bytenr(eb, fi) == 0)
+ return 0;
+
+ disk_bytenr = btrfs_file_extent_disk_bytenr(eb, fi);
+ disk_num_bytes = btrfs_file_extent_disk_num_bytes(eb, fi);
+ extent_num_bytes = btrfs_file_extent_num_bytes(eb, fi);
+
+ /* Check unaligned disk_num_bytes and num_bytes */
+ if (!IS_ALIGNED(disk_num_bytes, root->sectorsize)) {
+ error(
+"file extent [%llu, %llu] has unaligned disk num bytes: %llu, should be aligned to %u",
+ fi_key.objectid, fi_key.offset, disk_num_bytes,
+ root->sectorsize);
+ err |= BYTES_UNALIGNED;
+ } else {
+ data_bytes_allocated += disk_num_bytes;
+ }
+ if (!IS_ALIGNED(extent_num_bytes, root->sectorsize)) {
+ error(
+"file extent [%llu, %llu] has unaligned num bytes: %llu, should be aligned to %u",
+ fi_key.objectid, fi_key.offset, extent_num_bytes,
+ root->sectorsize);
+ err |= BYTES_UNALIGNED;
+ } else {
+ data_bytes_referenced += extent_num_bytes;
+ }
+ owner = btrfs_header_owner(eb);
+
+ /* Check the extent item of the file extent in extent tree */
+ btrfs_init_path(&path);
+ dbref_key.objectid = btrfs_file_extent_disk_bytenr(eb, fi);
+ dbref_key.type = BTRFS_EXTENT_ITEM_KEY;
+ dbref_key.offset = btrfs_file_extent_disk_num_bytes(eb, fi);
+
+ ret = btrfs_search_slot(NULL, extent_root, &dbref_key, &path, 0, 0);
+ if (ret) {
+ err |= BACKREF_MISSING;
+ goto error;
+ }
+
+ leaf = path.nodes[0];
+ slot = path.slots[0];
+ ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
+
+ extent_flags = btrfs_extent_flags(leaf, ei);
+ extent_gen = btrfs_extent_generation(leaf, ei);
+
+ if (!(extent_flags & BTRFS_EXTENT_FLAG_DATA)) {
+ error(
+ "extent[%llu %llu] backref type mismatch, wanted bit: %llx",
+ disk_bytenr, disk_num_bytes,
+ BTRFS_EXTENT_FLAG_DATA);
+ err |= BACKREF_MISMATCH;
+ }
+
+ if (file_extent_gen < extent_gen) {
+ error(
+"extent[%llu %llu] backref generation mismatch, wanted: <=%llu, have: %llu",
+ disk_bytenr, disk_num_bytes, file_extent_gen,
+ extent_gen);
+ err |= BACKREF_MISMATCH;
+ }
+
+ /* Check data backref inside that extent item */
+ item_size = btrfs_item_size_nr(leaf, path.slots[0]);
+ iref = (struct btrfs_extent_inline_ref *)(ei + 1);
+ ptr = (unsigned long)iref;
+ end = (unsigned long)ei + item_size;
+ while (ptr < end) {
+ iref = (struct btrfs_extent_inline_ref *)ptr;
+ type = btrfs_extent_inline_ref_type(leaf, iref);
+ dref = (struct btrfs_extent_data_ref *)(&iref->offset);
+
+ if (type == BTRFS_EXTENT_DATA_REF_KEY) {
+ ref_root = btrfs_extent_data_ref_root(leaf, dref);
+ if (ref_root == owner || ref_root == root->objectid)
+ found_dbackref = 1;
+ } else if (type == BTRFS_SHARED_DATA_REF_KEY) {
+ found_dbackref = !check_tree_block_ref(root, NULL,
+ btrfs_extent_inline_ref_offset(leaf, iref),
+ 0, owner);
+ }
+
+ if (found_dbackref)
+ break;
+ ptr += btrfs_extent_inline_ref_size(type);
+ }
+
+ /* Didn't found inlined data backref, try EXTENT_DATA_REF_KEY */
+ if (!found_dbackref) {
+ btrfs_release_path(&path);
+
+ btrfs_init_path(&path);
+ dbref_key.objectid = btrfs_file_extent_disk_bytenr(eb, fi);
+ dbref_key.type = BTRFS_EXTENT_DATA_REF_KEY;
+ dbref_key.offset = hash_extent_data_ref(root->objectid,
+ fi_key.objectid, fi_key.offset);
+
+ ret = btrfs_search_slot(NULL, root->fs_info->extent_root,
+ &dbref_key, &path, 0, 0);
+ if (!ret)
+ found_dbackref = 1;
+ }
+
+ if (!found_dbackref)
+ err |= BACKREF_MISSING;
+error:
+ btrfs_release_path(&path);
+ if (err & BACKREF_MISSING) {
+ error("data extent[%llu %llu] backref lost",
+ disk_bytenr, disk_num_bytes);
+ }
+ return err;
+}
+
+/*
+ * Get real tree block level for the case like shared block
+ * Return >= 0 as tree level
+ * Return <0 for error
+ */
+static int query_tree_block_level(struct btrfs_fs_info *fs_info, u64 bytenr)
+{
+ struct extent_buffer *eb;
+ struct btrfs_path path;
+ struct btrfs_key key;
+ struct btrfs_extent_item *ei;
+ u64 flags;
+ u64 transid;
+ u32 nodesize = btrfs_super_nodesize(fs_info->super_copy);
+ u8 backref_level;
+ u8 header_level;
+ int ret;
+
+ /* Search extent tree for extent generation and level */
+ key.objectid = bytenr;
+ key.type = BTRFS_METADATA_ITEM_KEY;
+ key.offset = (u64)-1;
+
+ btrfs_init_path(&path);
+ ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, &path, 0, 0);
+ if (ret < 0)
+ goto release_out;
+ ret = btrfs_previous_extent_item(fs_info->extent_root, &path, bytenr);
+ if (ret < 0)
+ goto release_out;
+ if (ret > 0) {
+ ret = -ENOENT;
+ goto release_out;
+ }
+
+ btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
+ ei = btrfs_item_ptr(path.nodes[0], path.slots[0],
+ struct btrfs_extent_item);
+ flags = btrfs_extent_flags(path.nodes[0], ei);
+ if (!(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
+ ret = -ENOENT;
+ goto release_out;
+ }
+
+ /* Get transid for later read_tree_block() check */
+ transid = btrfs_extent_generation(path.nodes[0], ei);
+
+ /* Get backref level as one source */
+ if (key.type == BTRFS_METADATA_ITEM_KEY) {
+ backref_level = key.offset;
+ } else {
+ struct btrfs_tree_block_info *info;
+
+ info = (struct btrfs_tree_block_info *)(ei + 1);
+ backref_level = btrfs_tree_block_level(path.nodes[0], info);
+ }
+ btrfs_release_path(&path);
+
+ /* Get level from tree block as an alternative source */
+ eb = read_tree_block_fs_info(fs_info, bytenr, nodesize, transid);
+ if (!extent_buffer_uptodate(eb)) {
+ free_extent_buffer(eb);
+ return -EIO;
+ }
+ header_level = btrfs_header_level(eb);
+ free_extent_buffer(eb);
+
+ if (header_level != backref_level)
+ return -EIO;
+ return header_level;
+
+release_out:
+ btrfs_release_path(&path);
+ return ret;
+}
+
+/*
+ * Check if a tree block backref is valid (points to a valid tree block)
+ * if level == -1, level will be resolved
+ * Return >0 for any error found and print error message
+ */
+static int check_tree_block_backref(struct btrfs_fs_info *fs_info, u64 root_id,
+ u64 bytenr, int level)
+{
+ struct btrfs_root *root;
+ struct btrfs_key key;
+ struct btrfs_path path;
+ struct extent_buffer *eb;
+ struct extent_buffer *node;
+ u32 nodesize = btrfs_super_nodesize(fs_info->super_copy);
+ int err = 0;
+ int ret;
+
+ /* Query level for level == -1 special case */
+ if (level == -1)
+ level = query_tree_block_level(fs_info, bytenr);
+ if (level < 0) {
+ err |= REFERENCER_MISSING;
+ goto out;
+ }
+
+ key.objectid = root_id;
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ key.offset = (u64)-1;
+
+ root = btrfs_read_fs_root(fs_info, &key);
+ if (IS_ERR(root)) {
+ err |= REFERENCER_MISSING;
+ goto out;
+ }
+
+ /* Read out the tree block to get item/node key */
+ eb = read_tree_block(root, bytenr, root->nodesize, 0);
+ if (!extent_buffer_uptodate(eb)) {
+ err |= REFERENCER_MISSING;
+ free_extent_buffer(eb);
+ goto out;
+ }
+
+ /* Empty tree, no need to check key */
+ if (!btrfs_header_nritems(eb) && !level) {
+ free_extent_buffer(eb);
+ goto out;
+ }
+
+ if (level)
+ btrfs_node_key_to_cpu(eb, &key, 0);
+ else
+ btrfs_item_key_to_cpu(eb, &key, 0);
+
+ free_extent_buffer(eb);
+
+ btrfs_init_path(&path);
+ /* Search with the first key, to ensure we can reach it */
+ ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+ if (ret) {
+ err |= REFERENCER_MISSING;
+ goto release_out;
+ }
+
+ node = path.nodes[level];
+ if (btrfs_header_bytenr(node) != bytenr) {
+ error(
+ "extent [%llu %d] referencer bytenr mismatch, wanted: %llu, have: %llu",
+ bytenr, nodesize, bytenr,
+ btrfs_header_bytenr(node));
+ err |= REFERENCER_MISMATCH;
+ }
+ if (btrfs_header_level(node) != level) {
+ error(
+ "extent [%llu %d] referencer level mismatch, wanted: %d, have: %d",
+ bytenr, nodesize, level,
+ btrfs_header_level(node));
+ err |= REFERENCER_MISMATCH;
+ }
+
+release_out:
+ btrfs_release_path(&path);
+out:
+ if (err & REFERENCER_MISSING) {
+ if (level < 0)
+ error("extent [%llu %d] lost referencer (owner: %llu)",
+ bytenr, nodesize, root_id);
+ else
+ error(
+ "extent [%llu %d] lost referencer (owner: %llu, level: %u)",
+ bytenr, nodesize, root_id, level);
+ }
+
+ return err;
+}
+
+/*
+ * Check referencer for shared block backref
+ * If level == -1, this function will resolve the level.
+ */
+static int check_shared_block_backref(struct btrfs_fs_info *fs_info,
+ u64 parent, u64 bytenr, int level)
+{
+ struct extent_buffer *eb;
+ u32 nodesize = btrfs_super_nodesize(fs_info->super_copy);
+ u32 nr;
+ int found_parent = 0;
+ int i;
+
+ eb = read_tree_block_fs_info(fs_info, parent, nodesize, 0);
+ if (!extent_buffer_uptodate(eb))
+ goto out;
+
+ if (level == -1)
+ level = query_tree_block_level(fs_info, bytenr);
+ if (level < 0)
+ goto out;
+
+ if (level + 1 != btrfs_header_level(eb))
+ goto out;
+
+ nr = btrfs_header_nritems(eb);
+ for (i = 0; i < nr; i++) {
+ if (bytenr == btrfs_node_blockptr(eb, i)) {
+ found_parent = 1;
+ break;
+ }
+ }
+out:
+ free_extent_buffer(eb);
+ if (!found_parent) {
+ error(
+ "shared extent[%llu %u] lost its parent (parent: %llu, level: %u)",
+ bytenr, nodesize, parent, level);
+ return REFERENCER_MISSING;
+ }
+ return 0;
+}
+