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btrfs-progs: check: introduce function to check referencer for data backref

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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>
This commit is contained in:
Lu Fengqi 2016-04-23 16:58:24 +08:00 committed by David Sterba
parent 1035ca5118
commit 4e6bbaebb8
1 changed files with 100 additions and 0 deletions
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100
cmds-check.c
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@ -9077,6 +9077,106 @@ 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)
{