On 04/25/2016 11:48 PM, Qu Wenruo wrote:
From: Lu Fengqi <lufq.fnst@xxxxxxxxxxxxxx>
Introduce a new function check_tree_block_backref() to check if a
backref points to correct referencer.
Signed-off-by: Lu Fengqi <lufq.fnst@xxxxxxxxxxxxxx>
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
---
cmds-check.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 95 insertions(+)
diff --git a/cmds-check.c b/cmds-check.c
index 6633b6e..81dd4f3 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -323,6 +323,8 @@ struct root_item_info {
#define MISSING_BACKREF (1 << 0) /* Completely no backref in extent tree */
#define BAD_BACKREF (1 << 1) /* Backref mismatch */
#define UNALIGNED_BYTES (1 << 2) /* Some bytes are not aligned */
+#define MISSING_REFERENCER (1 << 3) /* Referencer not found */
+#define BAD_REFERENCER (1 << 4) /* Referencer found, but not mismatch */
static void *print_status_check(void *p)
{
@@ -8736,6 +8738,99 @@ out:
return ret;
}
+/*
+ * Check if a tree block backref is valid (points to valid tree block)
+ * if level == -1, level will be resolved
+ */
+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 = MISSING_REFERENCER;
+ 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 |= MISSING_REFERENCER;
+ goto out;
+ }
+
+ /* Read out the tree block to get item/node key */
+ eb = read_tree_block(root, bytenr, root->nodesize, 0);
+ /* Impossible, as tree block query has read out the tree block */
+ if (!extent_buffer_uptodate(eb)) {
+ err |= MISSING_REFERENCER;
+ 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 |= MISSING_REFERENCER;
+ 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 |= BAD_REFERENCER;
+ }
+ 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 |= BAD_REFERENCER;
+ }
+
+release_out:
+ btrfs_release_path(&path);
+out:
+ if (err & MISSING_REFERENCER) {
+ 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;
Sigh I missed this at first, if you are doing flags don't return
negative numbers. Fix this and then you can add my reviewed-by. Thanks,
Josef
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