Re: btrfs check --repair: ERROR: cannot read chunk root

[Qu Wenruo]

At 10/31/2016 02:25 PM, Marc MERLIN wrote:
On Mon, Oct 31, 2016 at 02:04:10PM +0800, Qu Wenruo wrote:
Sorry for asking, am I doing this wrong?
myth:~# dd if=/dev/mapper/crypt_bcache0 of=/tmp/dump1 bs=512 count=32
skip=26367830208
dd: reading `/dev/mapper/crypt_bcache0': Invalid argument
0+0 records in
0+0 records out
0 bytes (0 B) copied, 0.000401393 s, 0.0 kB/s

So, the underlying MD RAID5 are complaining about some wrong data, and
refuse to read out.

It seems that btrfs-progs can't handle read failure?
Maybe dm-error could emulate it.

And what about the 2nd range?

they both fail the same, but I wasn' tsure if I typed the wrong dd command
or not.

Strange, your command seems OK to me.

Does it has anything to do with your security setup or something like that?
Or is it related to dm-crypt or bcache?


But this reminds me, if dd can't read it, maybe btrfs-progs is the same.

Maybe only kernel can read dm-crypt device while user space tools can't 
access dm-crypt devices directly?

Thanks,
Qu


myth:~# btrfs fi df /mnt/mnt
Data, single: total=13.22TiB, used=13.19TiB
System, DUP: total=32.00MiB, used=1.42MiB
Metadata, DUP: total=74.00GiB, used=72.82GiB
GlobalReserve, single: total=512.00MiB, used=0.00B
myth:~# btrfs fi show
Label: 'DS5'  uuid: 6692cf4c-93d9-438c-ac30-5db6381dc4f2
        Total devices 1 FS bytes used 13.26TiB
        devid    1 size 14.55TiB used 13.36TiB path /dev/mapper/crypt_bcache0

For now, I mounted the filesystem and I'm running scrub on it to see how
much damage there is. It will take all night:
BTRFS warning (device dm-0): checksum error at logical 27886878720 on dev 
/dev/mapper/crypt_bcache0, sector 56580096, root 9461, inode 45837, offset 
15460089856, length 4096, links 1 (path: system/mlocate/mlocate.db)
BTRFS error (device dm-0): bdev /dev/mapper/crypt_bcache0 errs: wr 0, rd 0, 
flush 0, corrupt 1, gen 0
BTRFS error (device dm-0): unable to fixup (regular) error at logical 
27887009792 on dev /dev/mapper/crypt_bcache0
BTRFS error (device dm-0): bdev /dev/mapper/crypt_bcache0 errs: wr 0, rd 0, 
flush 0, corrupt 2, gen 0
BTRFS error (device dm-0): unable to fixup (regular) error at logical 
27886878720 on dev /dev/mapper/crypt_bcache0
BTRFS warning (device dm-0): checksum error at logical 27885961216 on dev 
/dev/mapper/crypt_bcache0, sector 56578304, root 9461, inode 45837, offset 
15459172352, length 4096, links 1 (path: system/mlocate/mlocate.db)
BTRFS warning (device dm-0): checksum error at logical 27885830144 on dev 
/dev/mapper/crypt_bcache0, sector 56578048, root 9461, inode 45837, offset 
15459041280, length 4096, links 1 (path: system/mlocate/mlocate.db)
BTRFS error (device dm-0): bdev /dev/mapper/crypt_bcache0 errs: wr 0, rd 0, 
flush 0, corrupt 3, gen 0
BTRFS error (device dm-0): unable to fixup (regular) error at logical 
27885830144 on dev /dev/mapper/crypt_bcache0
BTRFS error (device dm-0): bdev /dev/mapper/crypt_bcache0 errs: wr 0, rd 0, 
flush 0, corrupt 4, gen 0
BTRFS error (device dm-0): unable to fixup (regular) error at logical 
27885961216 on dev /dev/mapper/crypt_bcache0
BTRFS warning (device dm-0): checksum error at logical 27887013888 on dev 
/dev/mapper/crypt_bcache0, sector 56580360, root 9461, inode 45837, offset 
15460225024, length 4096, links 1 (path: system/mlocate/mlocate.db)
BTRFS error (device dm-0): bdev /dev/mapper/crypt_bcache0 errs: wr 0, rd 0, 
flush 0, corrupt 5, gen 0
BTRFS error (device dm-0): unable to fixup (regular) error at logical 
27887013888 on dev /dev/mapper/crypt_bcache0
BTRFS warning (device dm-0): checksum error at logical 27885834240 on dev 
/dev/mapper/crypt_bcache0, sector 56578056, root 9461, inode 45837, offset 
15459045376, length 4096, links 1 (path: system/mlocate/mlocate.db)
BTRFS error (device dm-0): bdev /dev/mapper/crypt_bcache0 errs: wr 0, rd 0, 
flush 0, corrupt 6, gen 0
BTRFS error (device dm-0): unable to fixup (regular) error at logical 
27885834240 on dev /dev/mapper/crypt_bcache0
BTRFS warning (device dm-0): checksum error at logical 27887017984 on dev 
/dev/mapper/crypt_bcache0, sector 56580368, root 9461, inode 45837, offset 
15460229120, length 4096, links 1 (path: system/mlocate/mlocate.db)
BTRFS error (device dm-0): bdev /dev/mapper/crypt_bcache0 errs: wr 0, rd 0, 
flush 0, corrupt 7, gen 0
BTRFS error (device dm-0): unable to fixup (regular) error at logical 
27887017984 on dev /dev/mapper/crypt_bcache0

So far, it looks like mnior damage limited to one file, I'll see tomorrow 
morning after it's done reading the whole array

And further more, all backup chunk root are in facts pointing to current
chunk root, so --chunk-root doesn't work at all.

Ah, ok, so there is nothing I can do at the moment until I get a new 
btrfs-progs, correct?

Thanks for your answers
Marc



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