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docs/interop/qcow2: Improve bitmap flag in_use specification 

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metadata outdated, such as AUTO flag, which mirrors enabled/disabled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>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2019-03-11 21:51:44 +03:00 committed by John Snow
parent 796a3798ab
commit 2fd490c614
1 changed files with 6 additions and 3 deletions
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9
docs/interop/qcow2.txt
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@ -633,7 +633,10 @@ Structure of a bitmap directory entry:
Bit Bit
0: in_use 0: in_use
The bitmap was not saved correctly and may be 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contents may be outdated.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 1: auto
The bitmap must reflect all changes of the virtual The bitmap must reflect all changes of the virtual
@ -761,8 +764,8 @@ 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. 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 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 representation in RAM after each write or metadata change. Flag 'in_use'
bitmap is not synced. should be set while the bitmap is not synced.
In the image file the 'enabled' state is reflected by the 'auto' flag. If this 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 flag is set, the software must consider the bitmap as 'enabled' and start