Re: [PATCH] btrfs: relocation: output warning message for leftover v1 space cache before aborting current data balance

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2020/12/29 下午7:08, Stéphane Lesimple wrote:
> December 29, 2020 11:31 AM, "Qu Wenruo" <quwenruo.btrfs@gmx.com> wrote:
>
>>> # btrfs ins dump-tree -t root /dev/mapper/luks-tank-mdata | grep EXTENT_DA
>>> item 27 key (51933 EXTENT_DATA 0) itemoff 9854 itemsize 53
>>> item 12 key (72271 EXTENT_DATA 0) itemoff 14310 itemsize 53
>>> item 25 key (74907 EXTENT_DATA 0) itemoff 12230 itemsize 53
>>
>> Mind to dump all those related inodes?
>>
>> E.g:
>>
>> $ btrfs ins dump-tree -t root <dev> | gerp 51933 -C 10
>
> Sure. I added -w to avoid grepping big numbers just containing the digits 51933:
>
> # btrfs ins dump-tree -t root /dev/mapper/luks-tank-mdata | grep 51933 -C 10 -w
>                  generation 2614632 root_dirid 256 bytenr 42705449811968 level 2 refs 1
>                  lastsnap 2614456 byte_limit 0 bytes_used 101154816 flags 0x1(RDONLY)
>                  uuid 1100ff6c-45fa-824d-ad93-869c94a87c7b
>                  parent_uuid 8bb8a884-ea4f-d743-8b0c-b6fdecbc397c
>                  ctransid 1337630 otransid 1249372 stransid 0 rtransid 0
>                  ctime 1554266422.693480985 (2019-04-03 06:40:22)
>                  otime 1547877605.465117667 (2019-01-19 07:00:05)
>                  drop key (0 UNKNOWN.0 0) level 0
>          item 25 key (51098 ROOT_BACKREF 5) itemoff 10067 itemsize 42
>                  root backref key dirid 534 sequence 22219 name 20190119_070006_hourly.7
>          item 26 key (51933 INODE_ITEM 0) itemoff 9907 itemsize 160
>                  generation 0 transid 1517381 size 262144 nbytes 30553407488
>                  block group 0 mode 100600 links 1 uid 0 gid 0 rdev 0
>                  sequence 116552 flags 0x1b(NODATASUM|NODATACOW|NOCOMPRESS|PREALLOC)
>                  atime 0.0 (1970-01-01 01:00:00)
>                  ctime 1567904822.739884119 (2019-09-08 03:07:02)
>                  mtime 0.0 (1970-01-01 01:00:00)
>                  otime 0.0 (1970-01-01 01:00:00)
>          item 27 key (51933 EXTENT_DATA 0) itemoff 9854 itemsize 53
>                  generation 1517381 type 2 (prealloc)
>                  prealloc data disk byte 34626327621632 nr 262144
>                  prealloc data offset 0 nr 262144
>          item 28 key (52262 ROOT_ITEM 0) itemoff 9415 itemsize 439
>                  generation 2618893 root_dirid 256 bytenr 42677048360960 level 3 refs 1
>                  lastsnap 2618893 byte_limit 0 bytes_used 5557338112 flags 0x0(none)
>                  uuid d0d4361f-d231-6d40-8901-fe506e4b2b53
>                  ctransid 2618893 otransid 1277275 stransid 0 rtransid 0
>                  ctime 1609211576.181355141 (2020-12-29 04:12:56)
>                  otime 1550343531.349394412 (2019-02-16 19:58:51)
>
>> The point here is to show if we have INODE_ITEM here for the inode number.
>
> I think we do, if I understand the output correctly!
>
>> Although above ins dump should work, I just want to be extra sure about
>> where the -ENOENT comes from.
>>
>> Would you mind to test the following debug output?
>
> Here you go:
>
> [  438.260483] BTRFS info (device dm-10): balance: start -dvrange=34625344765952..34625344765953
> [  438.269018] BTRFS info (device dm-10): relocating block group 34625344765952 flags data|raid1
> [  450.439609] BTRFS info (device dm-10): found 167 extents, stage: move data extents
> [  451.026349] delete_v1_space_cache: no FILE_EXTENT found, leaf start=42676709441536 data_bytenr=34626327621632

This means the leaf returned by find_all_leafs() is not correct?!

Would you please try this one? (Need to clean up previous diff first):
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 19b7db8b2117..c4baffa78c0b 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2932,8 +2932,10 @@ static int delete_block_group_cache(struct
btrfs_fs_info *fs_info,
                 goto truncate;

         inode = btrfs_iget(fs_info->sb, ino, root);
-       if (IS_ERR(inode))
+       if (IS_ERR(inode)) {
+               pr_info("%s: no inode item found for ino %llu\n",
__func__, ino);
                 return -ENOENT;
+       }

  truncate:
         ret = btrfs_check_trunc_cache_free_space(fs_info,
@@ -2986,8 +2988,12 @@ static int delete_v1_space_cache(struct
extent_buffer *leaf,
                         break;
                 }
         }
-       if (!found)
+       if (!found) {
+               pr_info("%s: no FILE_EXTENT found, leaf start=%llu
data_bytenr=%llu\n",
+                       __func__, leaf->start, data_bytenr);
+               btrfs_print_leaf(leaf);
                 return -ENOENT;
+       }
         ret = delete_block_group_cache(leaf->fs_info, block_group, NULL,
                                         space_cache_ino);
         return ret;

Thanks,
Qu
> [  451.026353] BTRFS warning (device dm-10): leftover v1 space cache found, please use btrfs-check --clear-space-cache v1 to clean it up
> [  463.501781] BTRFS info (device dm-10): balance: ended with status: -2
>
> Regards,
>
> Stéphane.
>