[Gluster-devel] Spurious termination of fuse invalidation notifier thread
xhernandez at datalab.es
Mon Sep 5 07:16:43 UTC 2016
On 03/09/16 05:42, Raghavendra Gowdappa wrote:
> Hi Xavi/Kaleb/Pranith,
> During few of our older conversations (like , but not only one), some of you had reported that the thread which writes invalidation notifications (of inodes, entries) to /dev/fuse terminates spuriously. Csaba tried to reproduce the issue, but without success. It would be helpful if you provide any information on reproducer and/or possible reasons for the behavior.
I didn't found what really caused the problem. I only saw the
termination message on a production server after some days working but
hadn't had the opportunity to debug it.
Looking at the code, the only conclusion I got is that the result from
the write to /dev/fuse was unexpected. The patch solves this and I
haven't seen the problem again.
The old code only manages ENOENT error. It exits the thread for any
other error. I guess that in some situations a write to /dev/fuse can
return other "non fatal" errors.
As a guess, I think it may be a failure in an entry invalidation.
Looking at the code of fuse, it may return ENOTDIR if parent of the
entry is not a directory and some race happens doing rm/create while
sending invalidations in the background. Another possibility is
ENOTEMPTY if the entry references a non empty directory (again probably
caused by races between user mode operations and background
invalidations). Anyway this is only a guess, I have no more information.
>  http://review.gluster.org/#/c/13274/1/xlators/mount/fuse/src/fuse-bridge.c
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