[Gluster-users] I/O error repaired only by owner or root access

[Dan Bretherton]

On 02/25/2013 03:49 PM, Shawn Nock wrote:
> Dan Bretherton <d.a.bretherton at reading.ac.uk> writes:
>
>> Hello Rajesh- Here are the permissions.  The path in question is a
>> directory.
>>
>> [sms05dab at jupiter ~]$ ls -ld /users/gcs/WORK/ORCA1/ORCA1-R07-MEAN/Ctl
>> drwxr-xr-x 60 vq901510 nemo 110592 Feb 23 04:37
>> /users/gcs/WORK/ORCA1/ORCA1-R07-MEAN/Ctl [sms05dab at jupiter ~]$ ls -ld
>> /users/gcs/WORK/ORCA1/ORCA1-R07-MEAN lrwxrwxrwx 1 gcs nemo 49 Feb 1
>> 2012 /users/gcs/WORK/ORCA1/ORCA1-R07-MEAN ->
>> /data/pegasus/users/gcs/WORK/ORCA1/ORCA1-R07-MEAN [sms05dab at jupiter
>> ~]$ ls -ld /data/pegasus/users/gcs/WORK/ORCA1/ORCA1-R07-MEAN
>> drwxr-xr-x 27 gcs nemo 99210 Feb 23 03:14
>> /data/pegasus/users/gcs/WORK/ORCA1/ORCA1-R07-MEAN
>>
>> As you can see the parent directory in this case was a symlink but
>> that's not significant.  I ran the "ls -l" commands using my account -
>> sms05dab, but the problem was originally reported by user vq901510.
>> until I did "ls -l" as root neither of us could access the directory,
>> because the parent directory was owned by user gcs.  Usually the
>> problem is related to ownership of the file or directory itself.  This
>> is the first time I have seen the I/O error caused by parent directory
>> permissions.
>>
>> This problem seems to have started following an add-brick operation a
>> few weeks ago, after which I started "gluster volume rebalance
>> <VOLNAME> fix-layout" (which is still running). It occurred to me that
>> the problem could be related to link files, many of which need to be
>> rewritten following add-brick operations.  This could explain why the
>> ownership of the parent directory is significant, because users
>> sms05dab and vq901510 don't have permission to write in the parent
>> directory owned by user gcs.  Normally this wouldn't be a problem
>> because only read access to other users' data is required, but it
>> appears as though read access was being denied because the new link
>> file couldn't be written by unprivileged users.  Is this a plausible
>> explanation of the I/O error do you think?
> This sounds like my recent bug:
> https://bugzilla.redhat.com/show_bug.cgi?id=913699
>
> In the bug, I said that writing on the fuse mount of one of the brick
> servers fixed the problem.... but those were the only hosts I was
> attempting access as root.
>
Thanks Shawn. To confirm that we are seeing the same bug I will try 
accessing affected files from a FUSE mount on a server the next time it 
happens.
-Dan.

--
Dan Bretherton
ESSC Computer System Manager
Department of Meteorology
Harry Pitt Building, 3 Earley Gate
University of Reading
Reading, RG6 7BE (or RG6 6AL for postal service deliveries)
UK
Tel. +44 118 378 5205, Fax: +44 118 378 6413
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