On 4.10.19 г. 12:31 ч., Qu Wenruo wrote:
> [BUG]
> When running btrfs/063 in a loop, we got the following random write time
> tree checker error:
>
> BTRFS critical (device dm-4): corrupt leaf: root=18446744073709551610
> block=33095680 slot=2 ino=307 file_offset=0, invalid previous key objectid,
> have 305 expect 307
> BTRFS info (device dm-4): leaf 33095680 gen 7 total ptrs 47 free space
> 12146 owner 18446744073709551610
> BTRFS info (device dm-4): refs 1 lock (w:0 r:0 bw:0 br:0 sw:0 sr:0)
> lock_owner 0 current 26176
> item 0 key (305 1 0) itemoff 16123 itemsize 160
> inode generation 0 size 0 mode 40777
> item 1 key (305 12 257) itemoff 16111 itemsize 12
> item 2 key (307 108 0) itemoff 16058 itemsize 53 <<<
> extent data disk bytenr 0 nr 0
> extent data offset 0 nr 614400 ram 671744
> item 3 key (307 108 614400) itemoff 16005 itemsize 53
> extent data disk bytenr 195342336 nr 57344
> extent data offset 0 nr 53248 ram 57344
> item 4 key (307 108 667648) itemoff 15952 itemsize 53
> extent data disk bytenr 194048000 nr 4096
> extent data offset 0 nr 4096 ram 4096
> [...]
> BTRFS error (device dm-4): block=33095680 write time tree block corruption
> detected
> BTRFS: error (device dm-4) in btrfs_commit_transaction:2332: errno=-5 IO
> failure (Error while writing out transaction)
> BTRFS info (device dm-4): forced readonly
> BTRFS warning (device dm-4): Skipping commit of aborted transaction.
> BTRFS info (device dm-4): use zlib compression, level 3
> BTRFS: error (device dm-4) in cleanup_transaction:1890: errno=-5 IO failure
>
> [CAUSE]
> Commit 59b0d030fb30 ("btrfs: tree-checker: Try to detect missing INODE_ITEM")
> assumes all XATTR_ITEM/DIR_INDEX/DIR_ITEM/INODE_REF/EXTENT_DATA items
> should have previous key with the same objectid as ino.
>
> But it's only true for fs trees. For log-tree, we can get above log tree
> block where an EXTENT_DATA item has no previous key with the same ino.
> As log tree only records modified items, it won't record unmodified
> items like INODE_ITEM.
>
> So this triggers write time tree check warning.
>
> [FIX]
> As a quick fix, check header owner to skip the previous key if it's not
> fs tree (log tree doesn't count as fs tree).
>
> This fix is only to be merged as a quick fix.
> There will be a more comprehensive fix to refactor the common check into
> one function.
>
> Reported-by: David Sterba <dste...@suse.com>
> Fixes: 59b0d030fb30 ("btrfs: tree-checker: Try to detect missing INODE_ITEM")
> Signed-off-by: Qu Wenruo <w...@suse.com>
It's not entirely clear why this bug manifests. My tests show that when
we write extents we always update the inode's c/m time so it's always
dirtied hence it's logged. OTOH when punching a hole the same thing is
valid.
Filipe, under what conditions should it be possible to log an
EXTENT_DATA item without first logging the inode it belongs to? It seems
using the usual write paths (e.g. buffered write and punchole) that's
impossible?
> ---
> fs/btrfs/tree-checker.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> index b8f82d9be9f0..5e34cd5e3e2e 100644
> --- a/fs/btrfs/tree-checker.c
> +++ b/fs/btrfs/tree-checker.c
> @@ -148,7 +148,8 @@ static int check_extent_data_item(struct extent_buffer
> *leaf,
> * But if objectids mismatch, it means we have a missing
> * INODE_ITEM.
> */
> - if (slot > 0 && prev_key->objectid != key->objectid) {
> + if (slot > 0 && is_fstree(btrfs_header_owner(leaf)) &&
> + prev_key->objectid != key->objectid) {
> file_extent_err(leaf, slot,
> "invalid previous key objectid, have %llu expect %llu",
> prev_key->objectid, key->objectid);
> @@ -322,7 +323,8 @@ static int check_dir_item(struct extent_buffer *leaf,
> u32 cur = 0;
>
> /* Same check as in check_extent_data_item() */
> - if (slot > 0 && prev_key->objectid != key->objectid) {
> + if (slot > 0 && is_fstree(btrfs_header_owner(leaf)) &&
> + prev_key->objectid != key->objectid) {
> dir_item_err(leaf, slot,
> "invalid previous key objectid, have %llu expect %llu",
> prev_key->objectid, key->objectid);
>
