[Bugs] [Bug 1375959] Files not being opened with o_direct flag during random read operation ( Glusterfs 3.8.2)

[bugzilla at redhat.com]

https://bugzilla.redhat.com/show_bug.cgi?id=1375959

Krutika Dhananjay <kdhananj at redhat.com> changed:

           What    |Removed                     |Added
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              Flags|                            |needinfo?(shberry at redhat.co
                   |                            |m)



--- Comment #9 from Krutika Dhananjay <kdhananj at redhat.com> ---
So I checked the strace output again. The moment I disable open-behind, I start
to see O_DIRECT in the strace logs. I grepped for other invocations of open()
and realised there are all these files opened with O_WRONLY flag (without
O_DIRECT of course) with a lot of pwrites being invoked on their fds. Took me a
while to realise that these are filenames with patterns fio_bw*.log,
fio_clat*.log, fio_lat*.log, etc - in other words log files created by fio
itself which were ending up on the glusterfs mount point.

Possible dumb question inbound - Shekhar, did you invoke the fio command when
your current working directory was the glusterfs mount point itself? I made
that mistake today which is why I saw the same results as you did. :)

Could you please confirm this?

I ran the test again now, this time from $HOME. Disabling open-behind caused
things to work for me.

The bug report however is still valid, I will send out a patch to make
open-behind handle O_DIRECT. Meanwhile you can work around the issue by
disabling open-behind for now.

-Krutika

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