From: Lu Fengqi <lufq.fnst@xxxxxxxxxxxxxx>
Introduce function should_check() to reduced duplicated tree block check
for fs/subvolume tree.
The idea is, we only check the fs/subvolue tree block if we have the
highest referencer rootid, according to extent tree.
In that case, we can skip a lot of fs/subvolume tree block check if
there are a lot of snapshots.
Although we will do a lot of extent tree search for it.
Signed-off-by: Lu Fengqi <lufq.fnst@xxxxxxxxxxxxxx>
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
---
cmds-check.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 90 insertions(+)
diff --git a/cmds-check.c b/cmds-check.c
index db6fc8e..92f8aa1 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -9554,6 +9554,96 @@ next:
return err;
}
+/*
+ * Helper function for later fs/subvol tree check.
+ * To determine if a tree block should be checked.
+ * This function will ensure only the directly referencer with lowest
+ * rootid to check a fs/subvolume tree block.
+ *
+ * Backref check at extent tree would detect error like missing subvolume
+ * tree, so we can do aggressive judgement to reduce duplicated check.
+ */
+static int should_check(struct btrfs_root *root, struct extent_buffer *eb)
+{
+ struct btrfs_root *extent_root = root->fs_info->extent_root;
+ struct btrfs_key key;
+ struct btrfs_path path;
+ struct extent_buffer *leaf;
+ int slot;
+ struct btrfs_extent_item *ei;
+ unsigned long ptr;
+ unsigned long end;
+ int type;
+ u32 item_size;
+ u64 offset;
+ struct btrfs_extent_inline_ref *iref;
+ int ret;
+
+ btrfs_init_path(&path);
+ key.objectid = btrfs_header_bytenr(eb);
+ key.type = BTRFS_METADATA_ITEM_KEY;
+ key.offset = (u64)-1;
+
+ /*
+ * Any failure in backref resolving means we can't determine
+ * who the tree block belongs to.
+ * So in that case, we need to check that tree block
+ */
+ ret = btrfs_search_slot(NULL, extent_root, &key, &path, 0, 0);
+ if (ret < 0)
+ goto need_check;
+
+ ret = btrfs_previous_extent_item(extent_root, &path,
+ btrfs_header_bytenr(eb));
+ if (ret)
+ goto need_check;
+
+ 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) {
+ iref = (struct btrfs_extent_inline_ref *)(ei + 1);
+ } else {
+ struct btrfs_tree_block_info *info;
+
+ info = (struct btrfs_tree_block_info *)(ei + 1);
+ iref = (struct btrfs_extent_inline_ref *)(info + 1);
+ }
+
+ 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);
+
+ /*
+ * We only check the tree block if current root is
+ * the lowest referencer of it.
+ */
+ if (type == BTRFS_TREE_BLOCK_REF_KEY &&
+ offset < root->objectid) {
+ btrfs_release_path(&path);
+ return 0;
+ }
+
+ ptr += btrfs_extent_inline_ref_size(type);
+ }
+ /*
+ * Normally we should also check keyed tree block ref,
+ * but that may be very time consuming.
+ * Inlined ref should already make us skip a lot of refs now.
+ * So skip search keyed tree block ref.
+ */
+
+need_check:
+ btrfs_release_path(&path);
+ return 1;
+}
+
static int btrfs_fsck_reinit_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root, int overwrite)
{
--
2.8.0
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