From 0b5f477725d2652d671b42238ea58dbbdd4763a9 Mon Sep 17 00:00:00 2001
From: John Snow <jsnow@redhat.com>
Date: Wed, 3 Apr 2019 22:42:49 +0200
Subject: [PATCH 154/163] docs/interop/qcow2: Improve bitmap flag in_use
 specification

RH-Author: John Snow <jsnow@redhat.com>
Message-id: <20190403224253.5251-2-jsnow@redhat.com>
Patchwork-id: 85437
O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 1/5] docs/interop/qcow2: Improve bitmap flag in_use specification
Bugzilla: 1666884
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: Sergio Lopez Pascual <slp@redhat.com>

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

We already use (we didn't notice it) IN_USE flag for marking bitmap
metadata outdated, such as AUTO flag, which mirrors enabled/disabled
bitmaps. Now we are going to support bitmap resize, so it's good to
write IN_USE meaning with more details.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190311185147.52309-2-vsementsov@virtuozzo.com
Signed-off-by: John Snow <jsnow@redhat.com>
(cherry picked from commit 2fd490c614500fc669386eaf8710cd2d015f548e)
Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 docs/interop/qcow2.txt | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/docs/interop/qcow2.txt b/docs/interop/qcow2.txt
index feb711f..cba1787 100644
--- a/docs/interop/qcow2.txt
+++ b/docs/interop/qcow2.txt
@@ -555,7 +555,10 @@ Structure of a bitmap directory entry:
                     Bit
                       0: in_use
                          The bitmap was not saved correctly and may be
-                         inconsistent.
+                         inconsistent. Although the bitmap metadata is still
+                         well-formed from a qcow2 perspective, the metadata
+                         (such as the auto flag or bitmap size) or data
+                         contents may be outdated.
 
                       1: auto
                          The bitmap must reflect all changes of the virtual
@@ -683,8 +686,8 @@ corresponding range of the virtual disk (see above) was written to while the
 bitmap was 'enabled'. An unset bit means that this range was not written to.
 
 The software doesn't have to sync the bitmap in the image file with its
-representation in RAM after each write. Flag 'in_use' should be set while the
-bitmap is not synced.
+representation in RAM after each write or metadata change. Flag 'in_use'
+should be set while the bitmap is not synced.
 
 In the image file the 'enabled' state is reflected by the 'auto' flag. If this
 flag is set, the software must consider the bitmap as 'enabled' and start
-- 
1.8.3.1