Re: Input/output error on newly created file

[Nikolaus Rath <Nikolaus@rath.org>]

*ping*

Anyone any idea?

Best,
-Nikolaus

On May 09 2016, Nikolaus Rath <Nikolaus@rath.org> wrote:
> On May 09 2016, Filipe Manana <fdmanana@gmail.com> wrote:
>> On Sun, May 8, 2016 at 11:18 PM, Nikolaus Rath <Nikolaus@rath.org> wrote:
>>> Hello,
>>>
>>> I just created an innocent 10 MB on a btrfs file system, yet my attempt
>>> to read it a few seconds later (and ever since), just gives:
>>>
>>> $ ls -l in-progress/mysterious-io-error
>>> -rw-rw-r-- 1 nikratio nikratio 10485760 May  8 14:41 in-progress/mysterious-io-error
>>> $ cat in-progress/mysterious-io-error
>>> cat: in-progress/mysterious-io-error: Input/output error
>>
>> If you unmount and mount again the filesystem, does it happen again?
>
> After rebooting, the previously unaccessible file can now be read. But I
> cannot tell if it contains the right data.
>
> However, I just encountered the same problem with another, freshly
> created file.
>
>> How did you create the file?
>
> In Python 3. The equivalent code is more or less:
>
> with open('file.dat', 'wb+') as fh:
>      for buf in generate_data():
>          fh.write(buf) # bufsize is about 128 kB
>
>
> However, I should note that there is a lot of activity in this
> file system (it contains my home directory), so the above alone will
> probably not reproduce the problem.
>
> That said, so far both the problematic files were created by the same
> application (S3QL, of which luckily I am also the maintainer).
>
>
>> Does fsck reports any issues?
>
> Do you mean btrfsck? It actually has a lot to say:
>
> checking extents
> checking free space cache
> checking fs roots
> root 5 inode 3149867 errors 400, nbytes wrong
> root 5 inode 3150237 errors 400, nbytes wrong
> root 5 inode 3150238 errors 400, nbytes wrong
> root 5 inode 3150242 errors 400, nbytes wrong
> root 5 inode 3150260 errors 400, nbytes wrong
> [...]
> root 5 inode 15595011 errors 400, nbytes wrong
> root 5 inode 15595016 errors 400, nbytes wrong
> Checking filesystem on /dev/mapper/vg0-nikratio_crypt
> UUID: 8742472d-a9b0-4ab6-b67a-5d21f14f7a38
> found 263648960636 bytes used err is 1
> total csum bytes: 395314372
> total tree bytes: 908644352
> total fs tree bytes: 352735232
> total extent tree bytes: 95039488
> btree space waste bytes: 156301160
> file data blocks allocated: 675209801728
>  referenced 410351722496
> Btrfs v3.17
>
> However, the inode of the problematic file (16186241) is not
> mentioned. But I guess this is not surprising, because also for this
> file, I can read the contents after remounting.
>
>
> Best,
> -Nikolaus
>
>
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