Change in ovirt-hosted-engine-ha[master]: Use SYNC DIRECT IO everywhere to make sure all hosts see the...

[msivak at redhat.com]

Martin Sivák has submitted this change and it was merged.

Change subject: Use SYNC DIRECT IO everywhere to make sure all hosts see the same data
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Use SYNC DIRECT IO everywhere to make sure all hosts see the same data

We did remove direct io for LVM based backends as Python did not
supported that properly (http://bugs.python.org/issue5396).

The issue with direct io is that it requires page aligned buffers
for writes and reads. Python can't ensure that.

This patch uses a very nice workaround from
http://www.alexonlinux.com/direct-io-in-python that proposed to
use mmap to get the buffer. MMAPped memory is page aligned and
Python can use it for reads and writes.

Change-Id: I31912300b27a2ae215e2462114012676b43cb017
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1277079
Signed-off-by: Martin Sivak <msivak at redhat.com>
---
M ovirt_hosted_engine_ha/broker/storage_broker.py
M ovirt_hosted_engine_ha/lib/storage_backends.py
M ovirt_hosted_engine_ha/lib/util.py
3 files changed, 67 insertions(+), 25 deletions(-)

Approvals:
  Sandro Bonazzola: Looks good to me, but someone else must approve
  Martin Sivák: Verified; Looks good to me, approved; Passed CI tests



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Gerrit-MessageType: merged
Gerrit-Change-Id: I31912300b27a2ae215e2462114012676b43cb017
Gerrit-PatchSet: 9
Gerrit-Project: ovirt-hosted-engine-ha
Gerrit-Branch: master
Gerrit-Owner: Martin Sivák <msivak at redhat.com>
Gerrit-Reviewer: Adam Litke <alitke at redhat.com>
Gerrit-Reviewer: Allon Mureinik <amureini at redhat.com>
Gerrit-Reviewer: Federico Simoncelli <fsimonce at redhat.com>
Gerrit-Reviewer: Jenkins CI
Gerrit-Reviewer: Martin Sivák <msivak at redhat.com>
Gerrit-Reviewer: Nir Soffer <nsoffer at redhat.com>
Gerrit-Reviewer: Roy Golan <rgolan at redhat.com>
Gerrit-Reviewer: Sandro Bonazzola <sbonazzo at redhat.com>
Gerrit-Reviewer: Simone Tiraboschi <stirabos at redhat.com>
Gerrit-Reviewer: Tal Nisan <tnisan at redhat.com>
Gerrit-Reviewer: gerrit-hooks <automation at ovirt.org>