Change in ovirt-hosted-engine-ha[ovirt-hosted-engine-ha-1.3]: 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>
(cherry picked from commit 8b1e39ea7583d8a542cfaa3e67b7da3e788a008a)
---
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:
  Martin Sivák: Verified; Looks good to me, approved; Passed CI tests



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Gerrit-MessageType: merged
Gerrit-Change-Id: I31912300b27a2ae215e2462114012676b43cb017
Gerrit-PatchSet: 1
Gerrit-Project: ovirt-hosted-engine-ha
Gerrit-Branch: ovirt-hosted-engine-ha-1.3
Gerrit-Owner: Martin Sivák <msivak at redhat.com>
Gerrit-Reviewer: Martin Sivák <msivak at redhat.com>
Gerrit-Reviewer: gerrit-hooks <automation at ovirt.org>