[ceph-users] CephFS: clients hanging on write with ceph-fuse

Andras Pataki apataki at flatironinstitute.org
Fri Nov 3 12:48:43 PDT 2017


I've tested  the 12.2.1 fuse client - and it also reproduces the problem 
unfortunately.  Investigating the code that accesses the file system, it 
looks like multiple processes from multiple nodes write to the same file 
concurrently, but to different byte ranges of it.  Unfortunately the 
problem happens some hours into the run of the code, so I can't really 
run the MDS or fuse with a very high debug level that long.  Well, 
perhaps fuse I could run with a higher debug level on the nodes in 
question if that helps.

Andras


On 11/03/2017 12:29 AM, Gregory Farnum wrote:
> Either ought to work fine.
>
> On Thu, Nov 2, 2017 at 4:58 PM Andras Pataki 
> <apataki at flatironinstitute.org <mailto:apataki at flatironinstitute.org>> 
> wrote:
>
>     I'm planning to test the newer ceph-fuse tomorrow.  Would it be
>     better to stay with the Jewel 10.2.10 client, or would the 12.2.1
>     Luminous client be better (even though the back-end is Jewel for now)?
>
>
>     Andras
>
>
>
>     On 11/02/2017 05:54 PM, Gregory Farnum wrote:
>>     Have you tested on the new ceph-fuse? This does sound vaguely
>>     familiar and is an issue I'd generally expect to have the fix
>>     backported for, once it was identified.
>>
>>     On Thu, Nov 2, 2017 at 11:40 AM Andras Pataki
>>     <apataki at flatironinstitute.org
>>     <mailto:apataki at flatironinstitute.org>> wrote:
>>
>>         We've been running into a strange problem with Ceph using
>>         ceph-fuse and
>>         the filesystem. All the back end nodes are on 10.2.10, the
>>         fuse clients
>>         are on 10.2.7.
>>
>>         After some hours of runs, some processes get stuck waiting
>>         for fuse like:
>>
>>         [root at worker1144 ~]# cat /proc/58193/stack
>>         [<ffffffffa08cd241>] wait_answer_interruptible+0x91/0xe0 [fuse]
>>         [<ffffffffa08cd653>] __fuse_request_send+0x253/0x2c0 [fuse]
>>         [<ffffffffa08cd6d2>] fuse_request_send+0x12/0x20 [fuse]
>>         [<ffffffffa08d69d6>] fuse_send_write+0xd6/0x110 [fuse]
>>         [<ffffffffa08d84d5>] fuse_perform_write+0x2f5/0x5a0 [fuse]
>>         [<ffffffffa08d8a21>] fuse_file_aio_write+0x2a1/0x340 [fuse]
>>         [<ffffffff811fdfbd>] do_sync_write+0x8d/0xd0
>>         [<ffffffff811fe82d>] vfs_write+0xbd/0x1e0
>>         [<ffffffff811ff34f>] SyS_write+0x7f/0xe0
>>         [<ffffffff816975c9>] system_call_fastpath+0x16/0x1b
>>         [<ffffffffffffffff>] 0xffffffffffffffff
>>
>>         The cluster is healthy (all OSDs up, no slow requests,
>>         etc.).  More
>>         details of my investigation efforts are in the bug report I
>>         just submitted:
>>         http://tracker.ceph.com/issues/22008
>>
>>         It looks like the fuse client is asking for some caps that it
>>         never
>>         thinks it receives from the MDS, so the thread waiting for
>>         those caps on
>>         behalf of the writing client never wakes up.  The restart of
>>         the MDS
>>         fixes the problem (since ceph-fuse re-negotiates caps).
>>
>>         Any ideas/suggestions?
>>
>>         Andras
>>
>>         _______________________________________________
>>         ceph-users mailing list
>>         ceph-users at lists.ceph.com <mailto:ceph-users at lists.ceph.com>
>>         http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>
>

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