The NBD spec states that NBD_CMD_FLAG_REQ_ONE (which we currently
always use) should not reply with an extent larger than our request,
and that the server's response should be exactly one extent. Right
now, that means that if a server sends more than one extent, we treat
the server as broken, fail the block status request, and disconnect,
which prevents all further use of the block device. But while good
software should be strict in what it sends, it should be tolerant in
what it receives.
While trying to implement NBD_CMD_BLOCK_STATUS in nbdkit, we
temporarily had a non-compliant server sending too many extents in
spite of REQ_ONE. Oddly enough, 'qemu-img convert' with qemu 3.1
failed with a somewhat useful message:
qemu-img: Protocol error: invalid payload for NBD_REPLY_TYPE_BLOCK_STATUS
which then disappeared with commit d8b4bad8, on the grounds that an
error message flagged only at the time of coroutine teardown is
pointless, and instead we should rely on the actual failed API to
report an error - in other words, the 3.1 behavior was masking the
fact that qemu-img was not reporting an error. That has since been
fixed in the previous patch, where qemu-img convert now fails with:
qemu-img: error while reading block status of sector 0: Invalid argument
But even that is harsh. Since we already partially relaxed things in
commit acfd8f7a to tolerate a server that exceeds the cap (although
that change was made prior to the NBD spec actually putting a cap on
the extent length during REQ_ONE - in fact, the NBD spec change was
BECAUSE of the qemu behavior prior to that commit), it's not that much
harder to argue that we should also tolerate a server that sends too
many extents. But at the same time, it's nice to trace when we are
being tolerant of server non-compliance, in order to help server
writers fix their implementations to be more portable (if they refer
to our traces, rather than just stderr).
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190323212639.579-3-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
We know that the kernel implements a slow fallback code path for
BLKZEROOUT, so if BDRV_REQ_NO_FALLBACK is given, we shouldn't call it.
The other operations we call in the context of .bdrv_co_pwrite_zeroes
should usually be quick, so no modification should be needed for them.
If we ever notice that there are additional problematic cases, we can
still make these conditional as well.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Eric Blake <eblake@redhat.com>
Filter drivers that support .bdrv_co_pwrite_zeroes can safely advertise
BDRV_REQ_NO_FALLBACK because they just forward the request flags to
their child node.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Eric Blake <eblake@redhat.com>
For qemu-img convert, we want an operation that zeroes out the whole
image if this can be done efficiently, but that returns an error
otherwise so we don't write explicit zeroes and immediately overwrite
them with the real data, potentially doubling the amount of data to be
written.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Eric Blake <eblake@redhat.com>
There is only a single caller of bdrv_make_zero(), which is qemu-img
convert. If the function fails, we just fall back to a different method
of zeroing out blocks on the target image. There is no good reason to
print error messages on stderr when the higher level operation will
actually succeed.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Eric Blake <eblake@redhat.com>
Tracked down with cleanup-trace-events.pl. Funnies requiring manual
post-processing:
* block.c and blockdev.c trace points are in block/trace-events.
* hw/block/nvme.c uses the preprocessor to hide its trace point use
from cleanup-trace-events.pl.
* include/hw/xen/xen_common.h trace points are in hw/xen/trace-events.
* net/colo-compare and net/filter-rewriter.c use pseudo trace points
colo_compare_udp_miscompare and colo_filter_rewriter_debug to guard
debug code.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20190314180929.27722-5-armbru@redhat.com
Message-Id: <20190314180929.27722-5-armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
We spell out sub/dir/ in sub/dir/trace-events' comments pointing to
source files. That's because when trace-events got split up, the
comments were moved verbatim.
Delete the sub/dir/ part from these comments. Gets rid of several
misspellings.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190314180929.27722-3-armbru@redhat.com
Message-Id: <20190314180929.27722-3-armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Commit 509d39aa22 added support for read
only VMDKs of version 3.
This commit fixes the probe function to correctly handle descriptors of
version 3.
This commit has two effects:
1. We no longer need to supply '-f vmdk' when pointing to descriptor
files of version 3 in qemu/qemu-img command line arguments.
2. This fixes the scenario where a VMDK points to a parent version 3
descriptor file which is being probed as "raw" instead of "vmdk".
Reviewed-by: Arbel Moshe <arbel.moshe@oracle.com>
Reviewed-by: Mark Kanda <mark.kanda@oracle.com>
Signed-off-by: Shmuel Eiderman <shmuel.eiderman@oracle.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We were trying to check whether bdrv_open_blockdev_ref() returned
success, but accidentally checked the wrong variable. Spotted by
Coverity (CID 1399703).
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
While child_job_drained_begin() calls to job_pause(), the job doesn't
actually transition between states until it runs again and reaches a
pause point. This means bdrv_drained_begin() may return with some jobs
using the node still having 'busy == true'.
As a consequence, block_job_detach_aio_context() may get into a
deadlock, waiting for the job to be actually paused, while the coroutine
servicing the job is yielding and doesn't get the opportunity to get
scheduled again. This situation can be reproduced by issuing a
'block-commit' immediately followed by a 'device_del'.
To ensure bdrv_drained_begin() only returns when the jobs have been
paused, we change mirror_drained_poll() to only confirm it's quiesced
when job->paused == true and there aren't any in-flight requests, except
if we reached that point by a drained section initiated by the
mirror/commit job itself.
The other block jobs shouldn't need any changes, as the default
drained_poll() behavior is to only confirm it's quiesced if the job is
not busy or completed.
Signed-off-by: Sergio Lopez <slp@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* Add 'drop-cache=on|off' option to file-posix.c. The default is on.
Disabling the option fixes a QEMU 3.0.0 performance regression when live
migrating on the same host with cache.direct=off.
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Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging
Pull request
* Add 'drop-cache=on|off' option to file-posix.c. The default is on.
Disabling the option fixes a QEMU 3.0.0 performance regression when live
migrating on the same host with cache.direct=off.
# gpg: Signature made Wed 13 Mar 2019 11:07:48 GMT
# gpg: using RSA key 9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg: aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35 775A 9CA4 ABB3 81AB 73C8
* remotes/stefanha/tags/block-pull-request:
file-posix: add drop-cache=on|off option
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Commit dd577a26ff ("block/file-posix:
implement bdrv_co_invalidate_cache() on Linux") introduced page cache
invalidation so that cache.direct=off live migration is safe on Linux.
The invalidation takes a significant amount of time when the file is
large and present in the page cache. Normally this is not the case for
cross-host live migration but it can happen when migrating between QEMU
processes on the same host.
On same-host migration we don't need to invalidate pages for correctness
anyway, so an option to skip page cache invalidation is useful. I
investigated optimizing invalidation and detecting same-host migration,
but both are hard to achieve so a user-visible option will suffice.
As a bonus this option means that the cache invalidation feature will
now be detectable by libvirt via QMP schema introspection.
Suggested-by: Neil Skrypuch <neil@tembosocial.com>
Tested-by: Neil Skrypuch <neil@tembosocial.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20190307164941.3322-1-stefanha@redhat.com
Message-Id: <20190307164941.3322-1-stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
If we reopen a BlockDriverState and there is an option that is present
in bs->options but missing from the new set of options then we have to
return an error unless the driver is able to reset it to its default
value.
This patch adds a new 'mutable_opts' field to BlockDriver. This is
a list of runtime options that can be modified during reopen. If an
option in this list is unspecified on reopen then it must be reset (or
return an error).
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The bdrv_reopen_queue() function is used to create a queue with
the BDSs that are going to be reopened and their new options. Once
the queue is ready bdrv_reopen_multiple() is called to perform the
operation.
The original options from each one of the BDSs are kept, with the new
options passed to bdrv_reopen_queue() applied on top of them.
For "x-blockdev-reopen" we want a function that behaves much like
"blockdev-add". We want to ignore the previous set of options so that
only the ones actually specified by the user are applied, with the
rest having their default values.
One of the things that we need is a way to tell bdrv_reopen_queue()
whether we want to keep the old set of options or not, and that's what
this patch does. All current callers are setting this new parameter to
true and x-blockdev-reopen will set it to false.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Until now, with auto-read-only=on we tried to open the file read-write
first and if that failed, read-only was tried. This is actually not good
enough for libvirt, which gives QEMU SELinux permissions for read-write
only as soon as it actually intends to write to the image. So we need to
be able to switch between read-only and read-write at runtime.
This patch makes auto-read-only dynamic, i.e. the file is opened
read-only as long as no user of the node has requested write
permissions, but it is automatically reopened read-write as soon as the
first writer is attached. Conversely, if the last writer goes away, the
file is reopened read-only again.
bs->read_only is no longer set for auto-read-only=on files even if the
file descriptor is opened read-only because it will be transparently
upgraded as soon as a writer is attached. This changes the output of
qemu-iotests 232.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
In order to be able to dynamically reopen the file read-only or
read-write, depending on the users that are attached, we need to be able
to switch to a different file descriptor during the permission change.
This interacts with reopen, which also creates a new file descriptor and
performs permission changes internally. In this case, the permission
change code must reuse the reopen file descriptor instead of creating a
third one.
In turn, reopen can drop its code to copy file locks to the new file
descriptor because that is now done when applying the new permissions.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
There is no reason why we can take locks on the new file descriptor only
in raw_reopen_commit() where error handling isn't possible any more.
Instead, we can already do this in raw_reopen_prepare().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We'll want to access the file descriptor in the reopen_state while
processing permission changes in the context of the repoen.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Drop x- and x_ prefixes for latency histograms and update version to
4.0
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Since we now load all bitmaps into memory anyway, we can just truncate
them in-memory and then flush them back to disk. Just in case, we will
still check and enforce that this shortcut is valid -- i.e. that any
bitmap described on-disk is indeed in-memory and can be modified.
If there are any inconsistent bitmaps, we refuse to allow the truncate
as we do not actually load these bitmaps into memory, and it isn't safe
or reasonable to attempt to truncate corrupted data.
Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190311185147.52309-4-vsementsov@virtuozzo.com
[vsementsov: drop bitmap flushing, fix block comments style]
Signed-off-by: John Snow <jsnow@redhat.com>
We are going to allow image resize when there are persistent bitmaps.
It may lead to appearing of inconsistent bitmaps (IN_USE=1) with
inconsistent size. But we still want to load them as inconsistent.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190311185147.52309-3-vsementsov@virtuozzo.com
Signed-off-by: John Snow <jsnow@redhat.com>
Commit a88b179f introduced the ability to set and query bitmap
persistence, but with an atypical spelling.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-id: 20190308205845.25734-1-eblake@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Set the inconsistent bit on load instead of rejecting such bitmaps.
There is no way to un-set it; the only option is to delete the bitmap.
Obvervations:
- bitmap loading does not need to update the header for in_use bitmaps.
- inconsistent bitmaps don't need to have their data loaded; they're
glorified corruption sentinels.
- bitmap saving does not need to save inconsistent bitmaps back to disk.
- bitmap reopening DOES need to drop the readonly flag from inconsistent
bitmaps to allow reopening of qcow2 files with non-qemu-owned bitmaps
being eventually flushed back to disk.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20190301191545.8728-8-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
We didn't do any state checking on source bitmaps at all,
so this adds inconsistent and busy checks. readonly is
allowed, so you can still copy a readonly bitmap to a new
destination to use it for operations like drive-backup.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190301191545.8728-7-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Instead of checking against busy, inconsistent, or read only directly,
use a check function with permissions bits that let us streamline the
checks without reproducing them in many places.
Included in this patch are permissions changes that simply add the
inconsistent check to existing permissions call spots, without
addressing existing bugs.
In general, this means that busy+readonly checks become BDRV_BITMAP_DEFAULT,
which checks against all three conditions. busy-only checks become
BDRV_BITMAP_ALLOW_RO.
Notably, remove allows inconsistent bitmaps, so it doesn't follow the pattern.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190301191545.8728-4-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Even though the status field is deprecated, we still have to support
it for a few more releases. Since this is a very new kind of bitmap
state, it makes sense for it to have its own status field.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190301191545.8728-3-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Add an inconsistent bit to dirty-bitmaps that allows us to report a bitmap as
persistent but potentially inconsistent, i.e. if we find bitmaps on a qcow2
that have been marked as "in use".
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190301191545.8728-2-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Simply move the big status enum comment block to above the status
function, and document it as being deprecated. The whole confusing
block can get deleted in three releases time.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190223000614.13894-9-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
These mean the same thing now. Unify them and rename the merged call
bdrv_dirty_bitmap_busy to indicate semantically what we are describing,
as well as help disambiguate from the various _locked and _unlocked
versions of bitmap helpers that refer to mutex locks.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190223000614.13894-8-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Instead of implying a user_locked/busy status, make it explicit.
Now, bitmaps in use by migration, NBD or backup operations
are all treated the same way with the same code paths.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190223000614.13894-7-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Currently, the enabled predicate means something like:
"the QAPI status of the bitmap is ACTIVE."
After this patch, it should mean exclusively:
"This bitmap is recording guest writes, and is allowed to do so."
In many places, this is how this predicate was already used.
Internal usages of the bitmap QPI can call user_locked to find out if
the bitmap is in use by an operation.
To accommodate this, modify the create_successor routine to now
explicitly disable the parent bitmap at creation time.
Justifications:
1. bdrv_dirty_bitmap_status suffers no change from the lack of
1:1 parity with the new predicates because of the order in which
the predicates are checked. This is now only for compatibility.
2. bdrv_set_dirty() is unchanged: pre-patch, it was skipping bitmaps that were
disabled or had a successor, while post-patch it is only skipping bitmaps
that are disabled. To accommodate this, create_successor now ensures that
any bitmap with a successor is explicitly disabled.
3. qcow2_store_persistent_dirty_bitmaps: No functional change. This function
cares only about the literal enabled bit, and makes no effort to check if
the bitmap is in-use or not. After this patch there are still no ways to
produce an enabled bitmap with a successor.
4. block_dirty_bitmap_enable_prepare
block_dirty_bitmap_disable_prepare
init_dirty_bitmap_migration
nbd_export_new
These functions care about the literal enabled bit,
and already check user_locked separately.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190223000614.13894-5-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
bdrv_set_dirty_bitmap and bdrv_reset_dirty_bitmap are only used as an
internal API by the mirror and migration areas of our code. These
calls modify the bitmap, but do so at the behest of QEMU and not the
guest.
Presently, these bitmaps are always "enabled" anyway, but there's no
reason they have to be.
Modify these internal APIs to drop this assertion.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190223000614.13894-4-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
"Frozen" was a good description a long time ago, but it isn't adequate now.
Rename the frozen predicate to has_successor to make the semantics of the
predicate more clear to outside callers.
In the process, remove some calls to frozen() that no longer semantically
make sense. For bdrv_enable_dirty_bitmap_locked and
bdrv_disable_dirty_bitmap_locked, it doesn't make sense to prohibit QEMU
internals from performing this action when we only wished to prohibit QMP
users from issuing these commands. All of the QMP API commands for bitmap
manipulation already check against user_locked() to prohibit these actions.
Several other assertions really want to check that the bitmap isn't in-use
by another operation -- use the bitmap_user_locked function for this instead,
which presently also checks for has_successor. This leaves some redundant
checks of has_successor through different helpers that are addressed in
forthcoming patches.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190223000614.13894-3-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
The current API allows us to report a single status, which we've defined as:
Frozen: has a successor, treated as qmp_locked, may or may not be enabled.
Locked: no successor, qmp_locked. may or may not be enabled.
Disabled: Not frozen or locked, disabled.
Active: Not frozen, locked, or disabled.
The problem is that both "Frozen" and "Locked" mean nearly the same thing,
and that both of them do not intuit whether they are recording guest writes
or not.
This patch deprecates that status field and introduces two orthogonal
properties instead to replace it.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190223000614.13894-2-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
The glfs_*_async() functions do a callback once finished. This callback
has changed its arguments, pre- and post-stat structures have been
added. This makes it possible to improve caching, which is useful for
Samba and NFS-Ganesha, but not so much for QEMU. Gluster 6 is the first
release that includes these new arguments.
With an additional detection in ./configure, the new arguments can
conditionally get included in the glfs_io_cbk handler.
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
New versions of Glusters libgfapi.so have an updated glfs_ftruncate()
function that returns additional 'struct stat' structures to enable
advanced caching of attributes. This is useful for file servers, not so
much for QEMU. Nevertheless, the API has changed and needs to be
adopted.
Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Some Linux specific code is missing guards, leading to
build failure on OSX:
$ sudo brew install libiscsi
$ ./configure && make
[...]
CC block/iscsi.o
qemu/block/iscsi.c:338:24: error: 'iscsi_aiocb_info' defined but not used [-Werror=unused-const-variable=]
static const AIOCBInfo iscsi_aiocb_info = {
^~~~~~~~~~~~~~~~
qemu/block/iscsi.c:168:1: error: 'iscsi_schedule_bh' defined but not used [-Werror=unused-function]
iscsi_schedule_bh(IscsiAIOCB *acb)
^~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
Add guards to restrict this code for Linux.
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190220000553.28438-1-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Provide an option to force QEMU to always keep the external data file
consistent as a standalone read-only raw image.
At the moment, this means making sure that write_zeroes requests are
forwarded to the data file instead of just updating the metadata, and
checking that no backing file is used.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Rather than requiring that the external data file node is passed
explicitly when creating the qcow2 node, store the filename in the
designated header extension during .bdrv_create and read it from there
as a default during .bdrv_open.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
For external data files, data clusters must be excluded from the
refcount calculations. Instead, an implicit refcount of 1 is assumed for
the COPIED flag.
Compressed clusters and internal snapshots are incompatible with
external data files, so print an error if they are in use for images
with an external data file.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Internal snapshots and an external data file are incompatible because
snapshots require refcounting and non-linear mapping. Return an error
for all of the snapshot operations if an external data file is in use.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
