Re: btrfs random filesystem corruption in kernel 3.17

[David Arendt <admin@prnet.org>]

>From my own experience and based on what other people are saying, I
think there is a random btrfs filesystem corruption problem in kernel
3.17 at least related to snapshots, therefore I decided to post using
another subject to draw attention from people not concerned about btrfs
send to it. More information can be found in the brtfs send posts.

Did the filesystem you tried to balance contain snapshots ? Read only ones ?

On 10/13/2014 07:22 PM, Rich Freeman wrote:
> On Sun, Oct 12, 2014 at 7:11 AM, David Arendt <admin@prnet.org> wrote:
>> This weekend I finally had time to try btrfs send again on the newly
>> created fs. Now I am running into another problem:
>>
>> btrfs send returns: ERROR: send ioctl failed with -12: Cannot allocate
>> memory
>>
>> In dmesg I see only the following output:
>>
>> parent transid verify failed on 21325004800 wanted 2620 found 8325
>>
> I'm not using send at all, but I've been running into parent transid
> verify failed messages where the wanted is way smaller than the found
> when trying to balance a raid1 after adding a new drive.  Originally I
> had gotten a BUG, and after reboot the drive finished balancing
> (interestingly enough without moving any chunks to the new drive -
> just consolidating everything on the old drives), and then when I try
> to do another balance I get:
> [ 4426.987177] BTRFS info (device sdc2): relocating block group
> 10367073779712 flags 17
> [ 4446.287998] BTRFS info (device sdc2): found 13 extents
> [ 4451.330887] parent transid verify failed on 10063286579200 wanted
> 987432 found 993678
> [ 4451.350663] parent transid verify failed on 10063286579200 wanted
> 987432 found 993678
>
> The btrfs program itself outputs:
> btrfs balance start -v /data
> Dumping filters: flags 0x7, state 0x0, force is off
>   DATA (flags 0x0): balancing
>   METADATA (flags 0x0): balancing
>   SYSTEM (flags 0x0): balancing
> ERROR: error during balancing '/data' - Cannot allocate memory
> There may be more info in syslog - try dmesg | tail
>
> This is also on 3.17.  This may be completely unrelated, but it seemed
> similar enough to be worth mentioning.
>
> The filesystem otherwise seems to work fine, other than the new drive
> not having any data on it:
> Label: 'datafs'  uuid: cd074207-9bc3-402d-bee8-6a8c77d56959
>         Total devices 6 FS bytes used 2.16TiB
>         devid    1 size 2.73TiB used 2.40TiB path /dev/sdc2
>         devid    2 size 931.32GiB used 695.03GiB path /dev/sda2
>         devid    3 size 931.32GiB used 700.00GiB path /dev/sdb2
>         devid    4 size 931.32GiB used 700.00GiB path /dev/sdd2
>         devid    5 size 931.32GiB used 699.00GiB path /dev/sde2
>         devid    6 size 2.73TiB used 0.00 path /dev/sdf2
>
> This is btrfs-progs-3.16.2.
>
> --
> Rich