Re: corruption: yet another one after deleting a ro snapshot

[Christoph Anton Mitterer <calestyo@scientia.net>]

[-- Attachment #1: Type: text/plain, Size: 7155 bytes --]

On Thu, 2017-01-12 at 10:38 +0800, Qu Wenruo wrote:
> IIRC, RO mount won't continue background deletion.
I see.


> Would you please try 4.9 btrfs-progs?

Done now, see results (lowmem and original mode) below:

# btrfs version
btrfs-progs v4.9

# btrfs check /dev/nbd0 ; echo $?
Checking filesystem on /dev/nbd0
UUID: 326d292d-f97b-43ca-b1e8-c722d3474719
checking extents
ref mismatch on [37765120 16384] extent item 0, found 1
Backref 37765120 parent 6403 root 6403 not found in extent tree
backpointer mismatch on [37765120 16384]
owner ref check failed [37765120 16384]
ref mismatch on [51200000 16384] extent item 0, found 1
Backref 51200000 parent 6403 root 6403 not found in extent tree
backpointer mismatch on [51200000 16384]
owner ref check failed [51200000 16384]
ref mismatch on [78135296 16384] extent item 0, found 1
Backref 78135296 parent 6403 root 6403 not found in extent tree
backpointer mismatch on [78135296 16384]
owner ref check failed [78135296 16384]
ref mismatch on [5960381235200 16384] extent item 0, found 1
Backref 5960381235200 parent 6403 root 6403 not found in extent tree
backpointer mismatch on [5960381235200 16384]
checking free space cache
checking fs roots
checking csums
checking root refs
found 7483995824128 bytes used err is 0
total csum bytes: 7296183880
total tree bytes: 10875944960
total fs tree bytes: 2035286016
total extent tree bytes: 1015988224
btree space waste bytes: 920641324
file data blocks allocated: 8267656339456
 referenced 8389440876544
0


# btrfs check --mode=lowmem /dev/nbd0 ; echo $?
Checking filesystem on /dev/nbd0
UUID: 326d292d-f97b-43ca-b1e8-c722d3474719
checking extents
ERROR: block group[74117545984 1073741824] used 1073741824 but extent items used 0
ERROR: block group[239473786880 1073741824] used 1073741824 but extent items used 1207959552
ERROR: block group[500393050112 1073741824] used 1073741824 but extent items used 1207959552
ERROR: block group[581997428736 1073741824] used 1073741824 but extent items used 0
ERROR: block group[626557714432 1073741824] used 1073741824 but extent items used 0
ERROR: block group[668433645568 1073741824] used 1073741824 but extent items used 0
ERROR: block group[948680261632 1073741824] used 1073741824 but extent items used 0
ERROR: block group[982503129088 1073741824] used 1073741824 but extent items used 0
ERROR: block group[1039411445760 1073741824] used 1073741824 but extent items used 0
ERROR: block group[1054443831296 1073741824] used 1073741824 but extent items used 1207959552
ERROR: block group[1190809042944 1073741824] used 1073741824 but extent items used 0
ERROR: block group[1279392743424 1073741824] used 1073741824 but extent items used 0
ERROR: block group[1481256206336 1073741824] used 1073741824 but extent items used 0
ERROR: block group[1620842643456 1073741824] used 1073741824 but extent items used 1207959552
ERROR: block group[1914511032320 1073741824] used 1073741824 but extent items used 1207959552
ERROR: block group[3055361720320 1073741824] used 1073741824 but extent items used 0
ERROR: block group[3216422993920 1073741824] used 1073741824 but extent items used 0
ERROR: block group[3670615785472 1073741824] used 1073741824 but extent items used 1207959552
ERROR: block group[3801612288000 1073741824] used 1073741824 but extent items used 1207959552
ERROR: block group[3828455833600 1073741824] used 1073741824 but extent items used 1207959552
ERROR: block group[4250973241344 1073741824] used 1073741824 but extent items used 0
ERROR: block group[4261710659584 1073741824] used 1073741824 but extent items used 1074266112
ERROR: block group[4392707162112 1073741824] used 1073741824 but extent items used 0
ERROR: block group[4558063403008 1073741824] used 1073741824 but extent items used 0
ERROR: block group[4607455526912 1073741824] used 1073741824 but extent items used 0
ERROR: block group[4635372814336 1073741824] used 1073741824 but extent items used 0
ERROR: block group[4640204652544 1073741824] used 1073741824 but extent items used 0
ERROR: block group[4642352136192 1073741824] used 1073741824 but extent items used 1207959552
ERROR: block group[4681006841856 1073741824] used 1073741824 but extent items used 0
ERROR: block group[5063795802112 1073741824] used 1073741824 but extent items used 0
ERROR: block group[5171169984512 1073741824] used 1073741824 but extent items used 1207959552
ERROR: block group[5216267141120 1073741824] used 1073741824 but extent items used 1207959552
ERROR: block group[5290355326976 1073741824] used 1073741824 but extent items used 0
ERROR: block group[5445511020544 1073741824] used 1073741824 but extent items used 1074266112
ERROR: block group[6084387405824 1073741824] used 1073741824 but extent items used 0
ERROR: block group[6104788500480 1073741824] used 1073741824 but extent items used 0
ERROR: block group[6878956355584 1073741824] used 1073741824 but extent items used 0
ERROR: block group[6997067956224 1073741824] used 1073741824 but extent items used 0
ERROR: block group[7702516334592 1073741824] used 1073741824 but extent items used 0
ERROR: block group[8051482427392 1073741824] used 1073741824 but extent items used 1084751872
ERROR: block group[8116980678656 1073741824] used 1073217536 but extent items used 0
ERROR: extent[5960381235200 16384] backref lost (owner: 6403, level: 1)
ERROR: check node failed root 6403 bytenr 5960381235200 level 1, force continue check
ERROR: extent[51200000 16384] backref lost (owner: 257, level: 1)
ERROR: check node failed root 6403 bytenr 51200000 level 1, force continue check
ERROR: extent[37765120 16384] backref lost (owner: 257, level: 1)
ERROR: check node failed root 6403 bytenr 37765120 level 1, force continue check
ERROR: extent[78135296 16384] backref lost (owner: 257, level: 1)
ERROR: check node failed root 6403 bytenr 78135296 level 1, force continue check
ERROR: errors found in extent allocation tree or chunk allocation
checking free space cache
checking fs roots
found 7483995758592 bytes used err is -5
total csum bytes: 7296183880
total tree bytes: 11018780672
total fs tree bytes: 2178121728
total extent tree bytes: 1015988224
btree space waste bytes: 936782513
file data blocks allocated: 9157658292224
 referenced 9292573106176
1


It's the same fs as I was talking before, I just had to do it via NBD.


> But, I'm still not sure whether it's a false alert or a *REAL*
> corruption.
> 
> Even it may cause problem and corrupt your data, I still hope you
> could 
> do a rw mount and trigger a btrfs fi sync.
> 
> If it's a false alert, we can fix it then with ease.
> Or, it's a really big problem.

So what should I do next (as said, this is just a backup for me, so
while it would be annoying to recreate it (because nearly the full
8TiB) I could do it without any problem)... in terms of debugging this
issue?

Shall I rw-mount the fs and do sync and wait and retry? Or is there
anything else that you want me to try before in order to get the kernel
bug (if any) or btrfs-progs bug nailed down?


Cheers,
Chris.

[-- Attachment #2: smime.p7s --]
[-- Type: application/x-pkcs7-signature, Size: 5930 bytes --]