Commits 6a9ad15420 and 9004db48c0 added some
new text to qapi/migration.json which doesn't fit the stricter
indentation requirements imposed by the rST documentation generator.
Reindent those lines to the new standard.
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20200810195019.25427-2-peter.maydell@linaro.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Our current QAPI doc-comment markup allows section headers (introduced
with a leading '=' or '==') anywhere in a free-form documentation
comment. This works for Texinfo because the generator simply prints a
Texinfo section command at that point in the output stream. For rST
generation, since we're assembling a tree of docutils nodes, this is
awkward because a new section implies starting a new section node at
the top level of the tree and generating text into there.
Make section headers start a new free-form documentation block, so the
future rST document generator doesn't have to look at every line in
free-form blocks and handle headings in odd places.
This change makes no difference to the generated Texinfo.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200320091805.5585-3-armbru@redhat.com>
Section markup in definition documentation makes no sense and can
produce invalid Texinfo. Reject.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200320091805.5585-2-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
There are several problems here that can result in soft lockup,
depending on exactly where an interrupt or exception is delivered:
Include BIMM_FLAG in IFLAGS_TB_MASK, since it needs to follow D_FLAG.
Ensure that iflags is 0 when entering an interrupt/exception handler.
Add mb_cpu_synchronize_from_tb to restore iflags from tb->flags.
The change to t_sync_flags is cosmetic, but makes the code clearer.
This fixes the reported regression in acceptance/replay_kernel.py.
Fixes: 683a247ed7 ("target/microblaze: Store "current" iflags in insn_start")
Tested-by: Thomas Huth <thuth@redhat.com>
Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200904190842.2282109-2-richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
This is caught by "meson test", which complains about two tests with the
same name.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200904120342.11370-1-pbonzini@redhat.com>
Fixes: a2ce7dbd91 ("meson: convert tests/qtest to meson")
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Most jobs test the latest nettle library. This adds explicit coverage
for latest gcrypt using Fedora, and old gcrypt and nettle using
CentOS-7. The latter does a minimal tools-only build, as we only need to
validate that the crypto code builds and unit tests pass. Finally a job
disabling both nettle and gcrypt is provided to validate that gnutls
still works.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200901133050.381844-3-berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
If nettle is disabled and gcrypt enabled, the compiler and linker flags
needed for gcrypt are not passed.
Gnutls was also not added as a dependancy when gcrypt is enabled.
Attempting to add the library dependencies at the same time as the
source dependencies is error prone, as there are alot of different
rules for picking which sources to use, and some of the source files
use code level conditionals intead. It is thus clearer to add the
library dependencies separately.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200901133050.381844-2-berrange@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Now that we can use all our QEMU test containers in the gitlab-CI, we can
easily add some jobs that test cross-compilation for various architectures.
There is just only small ugliness: Since the shared runners on gitlab.com
are single-threaded, we have to split each compilation job into two parts
(--disable-user and --disable-system), and exclude some additional targets,
to avoid that the jobs are running too long and hitting the timeout of 1 h.
Message-Id: <20200823111757.72002-8-thuth@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
The linker of MinGW sometimes runs into the following problem:
libqemuutil.a(util_main-loop.c.obj): In function `qemu_fd_register':
/builds/huth/qemu/build/../util/main-loop.c:331: multiple definition of
`qemu_fd_register'
libqemuutil.a(stubs_fd-register.c.obj):/builds/huth/qemu/stubs/fd-register.c:5:
first defined here
collect2: error: ld returned 1 exit status
/builds/huth/qemu/rules.mak:88: recipe for target 'tests/test-timed-average.exe'
failed
qemu_fd_register() is defined in util/main-loop.c for WIN32, so let's simply
move the stub also there in the #else part of the corresponding #ifndef
to fix this problem.
Message-Id: <20200903054503.425435-1-thuth@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
When cross-compiling with MinGW, there are sometimes some weird linker
errors like:
ibqemuutil.a(util_main-loop.c.obj): In function `qemu_notify_event':
/builds/huth/qemu/build/../util/main-loop.c:139: multiple definition of
`qemu_notify_event'
libqemuutil.a(stubs_notify-event.c.obj):/builds/huth/qemu/stubs/notify-event.c:5:
first defined here
collect2: error: ld returned 1 exit status
/builds/huth/qemu/rules.mak:88: recipe for target 'tests/test-timed-average.exe'
failed
It seems like it works better when the qemu_timer_notify_cb() stub (which
calls qemu_notify_event()) is in a separate file - then we can also even
remove the qemu_notify_event() stub now.
This patch is based on ideas from the patch "stubs: Remove qemu_notify_event()"
by Philippe Mathieu-Daudé and the patch "cpu-timers, icount: new modules" from
Claudio Fontana.
Message-Id: <20200902102433.304737-1-thuth@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
The whpx variable is currently initialized to "no" which causes the WHPX
check to skip the detection unless the user specified --enable-whpx.
Since the detection code should be able to figure it out correctly, let's
initialized the variable to "" on MinGW-builds for proper auto-detection
instead.
Message-Id: <20200804170055.2851-11-thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Stefan Weil <sw@weilnetz.de>
Message-Id: <20200823111757.72002-7-thuth@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
To compile-test the WHPX accelerator, we need to download these system
headers first (they are unfortunately not part of any released and
packaged MinGW toolchain yet).
Idea taken from another patch by Stefan Weil.
Message-Id: <20200804170055.2851-12-thuth@redhat.com>
Message-Id: <20200823111757.72002-6-thuth@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
test-image-locking.c uses the qemu_lock_fd_test() function which is
only available on POSIX-like systems.
Message-Id: <20200804170055.2851-4-thuth@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-Id: <20200823111757.72002-4-thuth@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Fixes the following compiling error:
../tests/test-util-filemonitor.c: In function 'test_file_monitor_events':
../tests/test-util-filemonitor.c:620:17: error: too many arguments to function 'mkdir'
620 | if (mkdir(pathsrc, 0700) < 0) {
| ^~~~~
In file included from C:/CI-Tools/msys64/mingw64/x86_64-w64-mingw32/include/unistd.h:10,
from C:/work/xemu/qemu/include/qemu/osdep.h:93,
from ../tests/test-util-filemonitor.c:21:
C:/CI-Tools/msys64/mingw64/x86_64-w64-mingw32/include/io.h:282:15: note: declared here
282 | int __cdecl mkdir (const char *) __MINGW_ATTRIB_DEPRECATED_MSVC2005;
| ^~~~~
Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Message-Id: <20200905203425.1470-1-luoyonggang@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
../tests/test-vmstate.c: In function 'int_cmp':
../tests/test-vmstate.c:884:5: error: unknown type name 'uint'; did you mean 'uInt'?
884 | uint ua = GPOINTER_TO_UINT(a);
| ^~~~
| uInt
../tests/test-vmstate.c:885:5: error: unknown type name 'uint'; did you mean 'uInt'?
885 | uint ub = GPOINTER_TO_UINT(b);
| ^~~~
| uInt
make: *** [Makefile.ninja:5461：tests/test-vmstate.exe.p/test-vmstate.c.obj] 错误 1
Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Message-Id: <20200905063813.1875-1-luoyonggang@gmail.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
complete_and_wait() and wait_ready() currently only work for mirror
jobs. Let them work for active commit jobs, too.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Flushing a qcow2 node must lead to the data-file node being flushed as
well.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Parts of the block layer treat BDS.backing_file as if it were whatever
the image header says (i.e., if it is a relative path, it is relative to
the overlay), other parts treat it like a cache for
bs->backing->bs->filename (relative paths are relative to the CWD).
Considering bs->backing->bs->filename exists, let us make it mean the
former.
Among other things, this now allows the user to specify a base when
using qemu-img to commit an image file in a directory that is not the
CWD (assuming, everything uses relative filenames).
Before this patch:
$ ./qemu-img create -f qcow2 foo/bot.qcow2 1M
$ ./qemu-img create -f qcow2 -b bot.qcow2 foo/mid.qcow2
$ ./qemu-img create -f qcow2 -b mid.qcow2 foo/top.qcow2
$ ./qemu-img commit -b mid.qcow2 foo/top.qcow2
qemu-img: Did not find 'mid.qcow2' in the backing chain of 'foo/top.qcow2'
$ ./qemu-img commit -b foo/mid.qcow2 foo/top.qcow2
qemu-img: Did not find 'foo/mid.qcow2' in the backing chain of 'foo/top.qcow2'
$ ./qemu-img commit -b $PWD/foo/mid.qcow2 foo/top.qcow2
qemu-img: Did not find '[...]/foo/mid.qcow2' in the backing chain of 'foo/top.qcow2'
After this patch:
$ ./qemu-img commit -b mid.qcow2 foo/top.qcow2
Image committed.
$ ./qemu-img commit -b foo/mid.qcow2 foo/top.qcow2
qemu-img: Did not find 'foo/mid.qcow2' in the backing chain of 'foo/top.qcow2'
$ ./qemu-img commit -b $PWD/foo/mid.qcow2 foo/top.qcow2
Image committed.
With this change, bdrv_find_backing_image() must look at whether the
user has overridden a BDS's backing file. If so, it can no longer use
bs->backing_file, but must instead compare the given filename against
the backing node's filename directly.
Note that this changes the QAPI output for a node's backing_file. We
had very inconsistent output there (sometimes what the image header
said, sometimes the actual filename of the backing image). This
inconsistent output was effectively useless, so we have to decide one
way or the other. Considering that bs->backing_file usually at runtime
contained the path to the image relative to qemu's CWD (or absolute),
this patch changes QAPI's backing_file to always report the
bs->backing->bs->filename from now on. If you want to receive the image
header information, you have to refer to full-backing-filename.
This necessitates a change to iotest 228. The interesting information
it really wanted is the image header, and it can get that now, but it
has to use full-backing-filename instead of backing_file. Because of
this patch's changes to bs->backing_file's behavior, we also need some
reference output changes.
Along with the changes to bs->backing_file, stop updating
BDS.backing_format in bdrv_backing_attach() as well. This way,
ImageInfo's backing-filename and backing-filename-format fields will
represent what the image header says and nothing else.
iotest 245 changes in behavior: With the backing node no longer
overriding the parent node's backing_file string, you can now omit the
@backing option when reopening a node with neither a default nor a
current backing file even if it used to have a backing node at some
point.
273 also changes: The base image is opened without a format layer, so
ImageInfo.backing-filename-format used to report "file" for the base
image's overlay after blockdev-snapshot. However, the image header
never says "file" anywhere, so it now reports $IMGFMT.
Signed-off-by: Max Reitz <mreitz@redhat.com>
With bdrv_filter_bs(), we can easily handle this default filter behavior
in bdrv_co_block_status().
blkdebug wants to have an additional assertion, so it keeps its own
implementation, except bdrv_co_block_status_from_file() needs to be
inlined there.
Suggested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
We have to perform an active commit whenever the top node has a parent
that has taken the WRITE permission on it.
This means that block-commit's @backing-file parameter is no longer
allowed for such nodes, and that users will have to issue a
block-job-complete command. Neither should pose a problem in practice,
because this case was basically just broken until now.
(Since this commit already touches block-commit's documentation, it also
moves up the chunk explaining general block-commit behavior that for
some reason was situated under @backing-file.)
Signed-off-by: Max Reitz <mreitz@redhat.com>
We want to make it explicit where bs->backing is used, and we have done
so. The old role of backing_bs() is now effectively taken by
bdrv_cow_bs().
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
This changes iotest 204's output, because blkdebug on top of a COW node
used to make qemu-img map disregard the rest of the backing chain (the
backing chain was broken by the filter). With this patch, the
allocation in the base image is reported correctly.
Signed-off-by: Max Reitz <mreitz@redhat.com>
When looking for a dirty bitmap to share, we should handle filters by
just including them in the search (so they do not break backing chains).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
This includes some permission limiting (for example, we only need to
take the RESIZE permission if the base is smaller than the top).
Signed-off-by: Max Reitz <mreitz@redhat.com>
This includes some permission limiting (for example, we only need to
take the RESIZE permission for active commits where the base is smaller
than the top).
base_overlay is introduced so we can query bdrv_is_allocated_above() on
it - we cannot do that with base itself, because a filter's block_status
is the same as its child node, so if there are filters on base,
bdrv_is_allocated_above() on base would return information including
base.
Use this opportunity to rename qmp_drive_mirror()'s "source" BDS to
"target_backing_bs", because that is what it really refers to.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
query-block, query-named-block-nodes, and query-blockstats now return
any filtered child under "backing", not just bs->backing or COW
children. This is so that filters do not interrupt the reported backing
chain. This changes the output for iotest 184, as the throttled node
now appears as a backing child.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
It makes no sense to report the block stats of a purely metadata-storing
child in query-blockstats. So if the primary child does not have any
data, try to find a unique data-storing child.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
This allows us to differentiate between filters and nodes with COW
backing files: Filters cannot be used as overlays at all (for this
function).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
It is trivial, so we might as well do it.
Remove _filter_actual_image_size from iotest 184, so we get to see the
result in its reference output.
Signed-off-by: Max Reitz <mreitz@redhat.com>
There are two practical problems with bdrv_get_allocated_file_size()'s
default right now:
(1) For drivers with children, we should generally sum all their sizes
instead of just passing the request through to bs->file. The latter
is good for filters, but not so much for format drivers.
(2) Filters need not have bs->file, so we should actually go to the
filtered child instead of hard-coding bs->file.
Fix this by splitting the default implementation into three branches:
(1) For filter drivers: Return the size of the filtered child
(2) For protocol drivers: Return -ENOTSUP, because the default
implementation cannot make a guess
(3) For other drivers: Sum all data-bearing children's sizes
Signed-off-by: Max Reitz <mreitz@redhat.com>
When looking for a blkdebug node (which implements debug breakpoints),
use bdrv_primary_bs() to iterate through the graph, because that is
where a blkdebug node would be.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
If the top node's driver does not provide snapshot functionality and we
want to fall back to a node down the chain, we need to snapshot all
non-COW children. For simplicity's sake, just do not fall back if there
is more than one such child. Furthermore, we really only can fall back
to bs->file and bs->backing, because bdrv_snapshot_goto() has to modify
the child link (notably, set it to NULL).
Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
If a node whose driver does not provide VM state functions has a
metadata child, the VM state should probably go there; if it is a
filter, the VM state should probably go there. It follows that we
should generally go down to the primary child.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
bdrv_refresh_filename() and the kind of related bdrv_dirname() should
look to the primary child when they wish to copy the underlying file's
filename.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Instead of looking at just bs->file and bs->backing, we should look at
all children that could end up receiving forwarded requests.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Before HEAD^, we needed this because bdrv_co_flush() by itself would
only flush bs->file. With HEAD^, bdrv_co_flush() will flush all
children on which a WRITE or WRITE_UNCHANGED permission has been taken.
Thus, vmdk no longer needs to do it itself.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
If the driver does not support .bdrv_co_flush() so bdrv_co_flush()
itself has to flush the children of the given node, it should not flush
just bs->file->bs, but in fact all children that might have been written
to (judging from the permissions taken on them).
This is a bug fix for qcow2 images with an external data file, as they
so far did not flush that data_file node.
In any case, the BLKDBG_EVENT() should be emitted on the primary child,
because that is where a blkdebug node would be if there is any.
Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reopening a node's backing child needs a bit of special handling because
the "backing" child has different defaults than all other children
(among other things). Adding filter support here is a bit more
difficult than just using the child access functions. In fact, we often
have to directly use bs->backing because these functions are about the
"backing" child (which may or may not be the COW backing file).
Signed-off-by: Max Reitz <mreitz@redhat.com>
The condition modified here is not about potentially filtered children,
but only about COW sources (i.e. traditional backing files).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Use child access functions when iterating through backing chains so
filters do not break the chain.
In addition, bdrv_find_overlay() will now always return the actual
overlay; that is, it will never return a filter node but only one with a
COW backing file (there may be filter nodes between that node and @bs).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Because of the (not so recent anymore) changes that make the stream job
independent of the base node and instead track the node above it, we
have to split that "bottom" node into two cases: The bottom COW node,
and the node directly above the base node (which may be an R/W filter
or the bottom COW node).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Places that use patterns like
if (bs->drv->is_filter && bs->file) {
... something about bs->file->bs ...
}
should be
BlockDriverState *filtered = bdrv_filter_bs(bs);
if (filtered) {
... something about @filtered ...
}
instead.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Filters cannot compress data themselves but they have to implement
.bdrv_co_pwritev_compressed() still (or they cannot forward compressed
writes). Therefore, checking whether
bs->drv->bdrv_co_pwritev_compressed is non-NULL is not sufficient to
know whether the node can actually handle compressed writes. This
function looks down the filter chain to see whether there is a
non-filter that can actually convert the compressed writes into
compressed data (and thus normal writes).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
