@@ -313,6 +313,15 @@ struct root_item_info {
struct cache_extent cache_extent;
};
+/*
+ * Error bit for low memory mode check.
+ *
+ * Current no caller cares about it yet.
+ * Just as an internal use error classification
+ */
+#define BACKREF_MISSING (1 << 0) /* Backref missing in extent tree */
+#define BACKREF_MISMATCH (1 << 1) /* Backref exists but mismatch */
+
static void *print_status_check(void *p)
{
struct task_ctx *priv = p;
@@ -8402,6 +8411,158 @@ loop:
goto again;
}
+/*
+ * Check backrefs of a tree block given by @bytenr or @eb.
+ *
+ * @root: the root containin 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] backret lost(owner: %llu, level: %u)",
+ bytenr, nodesize, owner, level);
+ return err;
+}
+
static int btrfs_fsck_reinit_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root, int overwrite)
{