Messages in this thread | | | Date | Wed, 22 Jul 2015 10:09:23 +1000 | From | Dave Chinner <> | Subject | Re: [RFC PATCH] block: xfs: dm thin: train XFS to give up on retrying IO if thinp is out of space |
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On Tue, Jul 21, 2015 at 01:47:53PM -0400, Mike Snitzer wrote: > On Tue, Jul 21 2015 at 11:34am -0400, Eric Sandeen <sandeen@redhat.com> wrote: > > On 7/20/15 5:36 PM, Dave Chinner wrote: > > The issue we had discussed previously is that there is no agreement > > across block devices about whether ENOSPC is a permanent or temporary > > condition. Asking the admin to tune the fs to each block device's > > behavior sucks, IMHO. > > It does suck, but it beats the alternative of XFS continuing to do > nothing about the problem.
Just a comment on that: doing nothing is better than doing the wrong thing and being stuck with it forever. :)
> Disucssing more with Vivek, might be that XFS would be best served to > model what dm-thinp has provided with its 'no_space_timeout'. It > defaults to queueing IO for 60 seconds, once the timeout expires the > queued IOs getted errored. If set to 0 dm-thinp will queue IO > indefinitely.
Yes, that's exactly what I proposed in the thread I referenced in my previous email, and what got stuck on the bikeshed wall because of these concerns about knob twiddling:
http://oss.sgi.com/archives/xfs/2015-02/msg00346.html
| e.g. if we need configurable error handling, it needs to be | configurable for different error types, and it needs to be | configurable on a per-mount basis. And it needs to be configurable | at runtime, not just at mount time. That kind of leads to using | sysfs for this. e.g. for each error type we ned to handle different | behaviour for: | | $ cat /sys/fs/xfs/vda/meta_write_errors/enospc/type | [transient] permanent | $ cat /sys/fs/xfs/vda/meta_write_errors/enospc/perm_timeout_seconds | 300 | $ cat | /sys/fs/xfs/vda/meta_write_errors/enospc/perm_max_retry_attempts | 50 | $ cat | /sys/fs/xfs/vda/meta_write_errors/enospc/transient_fail_at_umount | 1
I've rebased this patchset, and I'm cleaning it up now, so in a few days I'll have something for review, likely for the 4.3 merge window....
Cheers,
Dave. -- Dave Chinner david@fromorbit.com
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