If you have the chain 'base.qcow2 <- top.qcow2' and want to merge a
bitmap from top into base, qemu-img was failing with:
qemu-img: Could not open 'top.qcow2': Could not open backing file: Failed to get shared "write" lock
Is another process using the image [base.qcow2]?
The easiest fix is to not open the entire backing chain of either
image (source or destination); after all, the point of 'qemu-img
bitmap' is solely to manipulate bitmaps directly within a single qcow2
image, and this is made more precise if we don't pay attention to
other images in the chain that may happen to have a bitmap by the same
name.
However, note that on a case-by-case analysis, there _are_ times where
we treat it as a feature that we can access a bitmap from a backing
layer in association with an overlay BDS. A demonstration of this is
using NBD to expose both an overlay BDS (for constant contents) and a
bitmap (for learning which blocks are interesting) during an
incremental backup:
Base <- Active <- Temporary
\--block job ->/
where Temporary is being fed by a backup 'sync=none' job. When
exposing Temporary over NBD, referring to a bitmap that lives only in
Active is less effort than having to copy a bitmap into Temporary [1].
So the testsuite additions in this patch check both where bitmaps get
allocated (the qemu-img info output), and that qemu-nbd is indeed able
to access a bitmap inherited from the backing chain since it is a
different use case than 'qemu-img bitmap'.
[1] Full disclosure: prior to the recent commit 374eedd1c4 and
friends, we were NOT able to see bitmaps through filters, which meant
that we actually did not have nice clean semantics for uniformly being
able to pick up bitmaps from anywhere in the backing chain (seen as a
change in behavior between qemu 4.1 and 4.2 at commit 00e30f05de, when
block-copy swapped from a one-off to a filter). Which means libvirt
was already coded to copy bitmaps around for the sake of older qemu,
even though modern qemu no longer needs it. Oh well.
Fixes: http://bugzilla.redhat.com/1877209
Reported-by: Eyal Shenitzky <eshenitz@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200914191009.644842-1-eblake@redhat.com>
[eblake: more commit message tweaks, per Max Reitz review]
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
820c6bee53 added testing of qcow2.py into 291, and it breaks 291
with external data file. Actually, 291 is bad place for qcow2.py
testing, better add a separate test.
For now, drop qcow2.py testing from 291 to fix the regression.
Fixes: 820c6bee53
Reported-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200618154052.8629-1-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Fixes: 5d72c68b49
Fixes: cf2d1203dc
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200617104822.27525-6-mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Depending on the granularity of holes and amount of metadata consumed
by a file, the 'disk size:' number of 'qemu-img info' is not reliable.
Adjust our test to use a different set of filters to avoid spurious
failures.
Reported-by: Kevin Wolf <kwolf@redhat.com>
Fixes: cf2d1203dc
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200608195629.3299649-1-eblake@redhat.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>
[eblake: fix merge conflict]
Signed-off-by: Eric Blake <eblake@redhat.com>
Add class for bitmap extension and dump its fields. Further work is to
dump bitmap directory.
Test new functionality inside 291 iotest.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200606081806.23897-14-vsementsov@virtuozzo.com>
[eblake: fix iotest output]
Signed-off-by: Eric Blake <eblake@redhat.com>
Add a new test covering the 'qemu-img bitmap' subcommand, as well as
'qemu-img convert --bitmaps', both added in recent patches.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200521192137.1120211-6-eblake@redhat.com>
Eric Blake
Vladimir Sementsov-Ogievskiy
Max Reitz