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authorLu Fengqi <lufq.fnst@cn.fujitsu.com>2016-04-23 16:58:24 +0800
committerDavid Sterba <dsterba@suse.com>2016-06-13 10:39:00 +0200
commit5843d41912d2d97c9ae4e7417ca23892c1e90956 (patch)
tree1460b310ec52ef63bb39e2620bad141ef443b960
parenta6fdfb8aaba795823217adf2838673cc4656d8ca (diff)
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btrfs-progs: check: introduce function to check referencer for data backref
Introduce new function check_extent_data_backref() to search referencer for a given data backref. Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
-rw-r--r--cmds-check.c100
1 files changed, 100 insertions, 0 deletions
diff --git a/cmds-check.c b/cmds-check.c
index 23c300b..a1921d5 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -8940,6 +8940,106 @@ out:
return 0;
}
+/*
+ * Check referencer for normal (inlined) data ref
+ * If len == 0, it will be resolved by searching in extent tree
+ */
+static int check_extent_data_backref(struct btrfs_fs_info *fs_info,
+ u64 root_id, u64 objectid, u64 offset,
+ u64 bytenr, u64 len, u32 count)
+{
+ struct btrfs_root *root;
+ struct btrfs_root *extent_root = fs_info->extent_root;
+ struct btrfs_key key;
+ struct btrfs_path path;
+ struct extent_buffer *leaf;
+ struct btrfs_file_extent_item *fi;
+ u32 found_count = 0;
+ int slot;
+ int ret = 0;
+
+ if (!len) {
+ key.objectid = bytenr;
+ key.type = BTRFS_EXTENT_ITEM_KEY;
+ key.offset = (u64)-1;
+
+ btrfs_init_path(&path);
+ ret = btrfs_search_slot(NULL, extent_root, &key, &path, 0, 0);
+ if (ret < 0)
+ goto out;
+ ret = btrfs_previous_extent_item(extent_root, &path, bytenr);
+ if (ret)
+ goto out;
+ btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
+ if (key.objectid != bytenr ||
+ key.type != BTRFS_EXTENT_ITEM_KEY)
+ goto out;
+ len = key.offset;
+ btrfs_release_path(&path);
+ }
+ key.objectid = root_id;
+ btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
+ key.offset = (u64)-1;
+ btrfs_init_path(&path);
+
+ root = btrfs_read_fs_root(fs_info, &key);
+ if (IS_ERR(root))
+ goto out;
+
+ key.objectid = objectid;
+ key.type = BTRFS_EXTENT_DATA_KEY;
+ /*
+ * It can be nasty as data backref offset is
+ * file offset - file extent offset, which is smaller or
+ * equal to original backref offset. The only special case is
+ * overflow. So we need to special check and do further search.
+ */
+ key.offset = offset & (1ULL << 63) ? 0 : offset;
+
+ ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+ if (ret < 0)
+ goto out;
+
+ /*
+ * Search afterwards to get correct one
+ * NOTE: As we must do a comprehensive check on the data backref to
+ * make sure the dref count also matches, we must iterate all file
+ * extents for that inode.
+ */
+ while (1) {
+ leaf = path.nodes[0];
+ slot = path.slots[0];
+
+ btrfs_item_key_to_cpu(leaf, &key, slot);
+ if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
+ break;
+ fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
+ /*
+ * Except normal disk bytenr and disk num bytes, we still
+ * need to do extra check on dbackref offset as
+ * dbackref offset = file_offset - file_extent_offset
+ */
+ if (btrfs_file_extent_disk_bytenr(leaf, fi) == bytenr &&
+ btrfs_file_extent_disk_num_bytes(leaf, fi) == len &&
+ (u64)(key.offset - btrfs_file_extent_offset(leaf, fi)) ==
+ offset)
+ found_count++;
+
+ ret = btrfs_next_item(root, &path);
+ if (ret)
+ break;
+ }
+out:
+ btrfs_release_path(&path);
+ if (found_count != count) {
+ error(
+"extent[%llu, %llu] referencer count mismatch (root: %llu, owner: %llu, offset: %llu) wanted: %u, have: %u",
+ bytenr, len, root_id, objectid, offset, count, found_count);
+ return REFERENCER_MISSING;
+ }
+ return 0;
+}
+
static int btrfs_fsck_reinit_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root, int overwrite)
{