All major distributions do support libseccomp version >= 2.3.0, so there
is no need to special-case on various architectures any longer.
Signed-off-by: NHelge Deller <deller@gmx.de>
Message-Id: <20190404183923.GA22347@ls3530.dellerweb.de>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Acked-by: NEduardo Otubo <otubo@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: NThomas Huth <thuth@redhat.com>

When running "make" in a build directory from the pre-Kconfig merge time,
the build process currently fails with:

 make: *** No rule to make target `.../default-configs/pci.mak',
  needed by `aarch64-softmmu/config-devices.mak'.  Stop.

To make sure that this problem at least goes away when the user runs
"configure" (or "sh config.status") again, we have to make sure that
we re-generate the .mak.d files. Thus remove the old stale files
while running the configure script.

Message-Id: <1552300145-12526-1-git-send-email-thuth@redhat.com>
Signed-off-by: NThomas Huth <thuth@redhat.com>

Without the -Wno-typedef-redefinition option, clang complains if a typedef
gets redefined in gnu99 mode (since this is officially a C11 feature). This
used to also happen with older versions of GCC, but since we've bumped our
minimum GCC version to 4.8, all versions of GCC that we support do not seem
to issue this warning in gnu99 mode anymore. So this has become a common
problem for people who only test their code with GCC - they do not notice
the issue until they submit their patches and suddenly patchew or a
maintainer complains.

Now that we do not urgently need to keep the code clean from typedef
redefintions anymore with recent versions of GCC, we can ease the
situation with clang, too, and simply shut these warnings off for good.
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Message-Id: <20190427154539.11336-1-thuth@redhat.com>
Signed-off-by: NThomas Huth <thuth@redhat.com>

The field is not used anymore, we can remove it.
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190422210448.2488-4-ehabkost@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> [on mingw64]
Reviewed-by: NThomas Huth <thuth@redhat.com>
Signed-off-by: NThomas Huth <thuth@redhat.com>

qtest_available() will always return 0 on non-POSIX systems.
It's simpler to just not compile the accelerator code on those
systems instead of relying on the AccelClass::available function.
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190422210448.2488-3-ehabkost@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> [on mingw64]
Reviewed-by: NThomas Huth <thuth@redhat.com>
Signed-off-by: NThomas Huth <thuth@redhat.com>

QTest has two parts: the server (-qtest) and the accelerator
(-machine accel=qtest).  The accelerator depends on CONFIG_POSIX
due to its usage of sigwait(), but the server doesn't.

Move the accel code to accel/qtest.c.  Later we will disable
compilation of accel/qtest.c on non-POSIX systems.
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190422210448.2488-2-ehabkost@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
[thuth: added fixup for MAINTAINERS file]
Signed-off-by: NThomas Huth <thuth@redhat.com>

So far we do not have any test coverage for TCI (the TCG interpreter) yet.
Thus let's add a CI pipeline that runs at least some basic TCG tests with
a TCI build, to make sure that there are no further regressions.
Signed-off-by: NThomas Huth <thuth@redhat.com>
Message-Id: <20190410123550.2362-1-thuth@redhat.com>

Pull request

# gpg: Signature made Wed 01 May 2019 21:24:16 BST
# gpg:                using RSA key F9B7ABDBBCACDF95BE76CBD07DEF8106AAFC390E
# gpg: Good signature from "John Snow (John Huston) <jsnow@redhat.com>" [full]
# Primary key fingerprint: FAEB 9711 A12C F475 812F  18F2 88A9 064D 1835 61EB
#      Subkey fingerprint: F9B7 ABDB BCAC DF95 BE76  CBD0 7DEF 8106 AAFC 390E

* remotes/jnsnow/tags/bitmaps-pull-request:
  docs/interop/bitmaps: rewrite and modernize doc
  Makefile: add nit-picky mode to sphinx-build
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

HMP pull

New gva2gpa command
delvm now uses hmp_handle_error so gets Error: prefix in messages

# gpg: Signature made Wed 01 May 2019 11:57:43 BST
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" [full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert/tags/pull-hmp-20190501:
  hmp: gva2gpa debug command
  hmp: delvm: use hmp_handle_error
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

This just about rewrites the entirety of the bitmaps.rst document to
make it consistent with the 4.0 release. I have added new features seen
in the 4.0 release, as well as tried to clarify some points that keep
coming up when discussing this feature both in-house and upstream.

It does not yet cover pull backups or migration details, but I intend to
keep extending this document to cover those cases.
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Reviewed-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190426221528.30293-3-jsnow@redhat.com
[Adjusted commit message. --js]
Signed-off-by: NJohn Snow <jsnow@redhat.com>

If we add references that don't resolve (or accidentally remove them),
it will be helpful to have warning messages alerting us to that.

Further, turn those warnings into errors so we can be alerted to these
problems sooner rather than later.
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Reviewed-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190426221528.30293-2-jsnow@redhat.com
[adjusted commit message. --js]
Signed-off-by: NJohn Snow <jsnow@redhat.com>

Add a gva2gpa command purely for debug which performs
address translation on the gva, the existing gpa2hva
command can then also be used to find it in the qemu
userspace; e.g.

(qemu) info registers
.... RSP=ffffffff81c03e98
....
(qemu) gva2gpa 0xffffffff81c03e98
gpa: 0x1c03e98
(qemu) gpa2hva 0x1c03e98
Host virtual address for 0x1c03e98 (pc.ram) is 0x7f0599a03e98
(qemu) x/10x 0xffffffff81c03e98
ffffffff81c03e98: 0x81c03eb8 0xffffffff 0x8101ea3f 0xffffffff
ffffffff81c03ea8: 0x81d27b00 0xffffffff 0x00000000 0x00000000
ffffffff81c03eb8: 0x81c03ec8 0xffffffff

gdb -p ...qemu...
(gdb) x/10x 0x7f0599a03e98
0x7f0599a03e98:	0x81c03eb8	0xffffffff	0x8101ea3f	0xffffffff
0x7f0599a03ea8:	0x81d27b00	0xffffffff	0x00000000	0x00000000
0x7f0599a03eb8:	0x81c03ec8	0xffffffff
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190412152652.827-1-dgilbert@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>

This gives us the consistent 'Error:' prefix added in 66363e9a,
which helps users like libvirt who still need to scrape hmp error
messages to detect failure.
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>
Message-Id: <984634226fa14316641f31f84e7dd0bb770bd94c.1556141033.git.crobinso@redhat.com>
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>

Block layer patches:

- iotests: Fix output of qemu-io related tests
- Don't ignore bdrv_set_aio_context() for nodes with bs->drv = NUL
- vmdk: Set vmdk parent backing_format to vmdk
- qcow2: Preallocation fixes (especially for external data files)
- Add linear-buffer-based APIs (as wrappers around qiov-based ones)
- Various code cleanups and small corner case fixes

# gpg: Signature made Tue 30 Apr 2019 16:35:09 BST
# gpg:                using RSA key 7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream: (27 commits)
  block/qed: add missed coroutine_fn markers
  iotests: Check that images are in read-only mode after block-commit
  commit: Make base read-only if there is an early failure
  qemu-img: use buffer-based io
  block/stream: use buffer-based io
  block/commit: use buffer-based io
  block/backup: use buffer-based io
  block/parallels: use buffer-based io
  block/qed: use buffer-based io
  block/qcow: use buffer-based io
  block/qcow2: use buffer-based io
  block: introduce byte-based io helpers
  qcow2: Fix error handling in the compression code
  qcow2: Fix qcow2_make_empty() with external data file
  qemu-img: Make create hint at protocol options
  iotests: Perform the correct test in 082
  qcow2: Fix full preallocation with external data file
  qcow2: Add errp to preallocate_co()
  qcow2: Avoid COW during metadata preallocation
  qemu-img: Saner printing of large file sizes
  ...
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

qed_read_table and qed_write_table use coroutine-only interfaces but
are not marked coroutine_fn. Happily, they are called only from
coroutine context, so we only need to add missed markers.
Reported-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This tests the fix from the previous patch.
Signed-off-by: NAlberto Garcia <berto@igalia.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

You can reproduce this by passing an invalid filter-node-name (like
"1234") to block-commit. In this case the base image is put in
read-write mode but is never reset back to read-only.
Signed-off-by: NAlberto Garcia <berto@igalia.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Move to _co_ versions of io functions qed_read_table() and
qed_write_table(), as we use qemu_co_mutex_unlock()
anyway.
Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This patch fixes a few things in the way error codes are handled in
the qcow2 compression code:

a) qcow2_co_pwritev_compressed() expects qcow2_co_compress() to only
   return -1 or -2 on failure, but this is not correct. Since the
   change from qcow2_compress() to qcow2_co_compress() in commit
   ceb029cd the new code can also return -EINVAL (although
   there does not seem to exist any code path that would cause that
   error in the current implementation).

b) -1 and -2 are ad-hoc error codes defined in qcow2_compress().
   This patch replaces them with standard constants from errno.h.

c) Both qcow2_compress() and qcow2_co_do_compress() return a negative
   value on failure, but qcow2_co_pwritev_compressed() stores the
   value in an unsigned data type.
Signed-off-by: NAlberto Garcia <berto@igalia.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

make_completely_empty() is an optimisated path for bdrv_make_empty()
where completely new metadata is created inside the image file instead
of going through all clusters and discarding them. For an external data
file, however, we actually need to do discard operations on the data
file; just overwriting the qcow2 file doesn't get rid of the data.

The necessary slow path with an explicit discard operation already
exists for other cases. Use it for external data files, too.

Cc: qemu-stable@nongnu.org
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

qemu-img create allows giving just a format and "-o help" to get a list
of the options supported by that format.  Users may not realize that the
protocol level may offer even more options, which they only get to see
by specifying a filename.

This patch adds a note to hint at that fact.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

In the "amend" section of 082, we perform a single "convert" test
(namely "convert -o help").  That does not make sense, especially
because we have done exactly that "convert" test earlier in 082 already.

Replacing "convert" by "amend" yields an error, which is correct because
there is no point in "amend" having a default format.  The user has to
either specify the format, or give a file for qemu-img to probe.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

preallocate_co() already gave the data file the full size without
forwarding the requested preallocation mode to the protocol. When
bdrv_co_truncate() was called later with the preallocation mode, the
file didn't actually grow any more, so the data file stayed unallocated
even if full preallocation was requested.

Pass the right preallocation mode to preallocate_co() and remove the
second bdrv_co_truncate() to fix this. As a side effect, the ugly
one-byte write in preallocate_co() is replaced with a truncate call,
now leaving the last block unallocated on the protocol level as it
should be.

Cc: qemu-stable@nongnu.org
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

We'll add a bdrv_co_truncate() call in the next patch which can return
an Error that we don't want to discard. So add an errp parameter to
preallocate_co().

Cc: qemu-stable@nongnu.org
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Limiting the allocation to INT_MAX bytes isn't particularly clever
because it means that the final cluster will be a partial cluster which
will be completed through a COW operation. This results in unnecessary
data read and write requests which lead to an unwanted non-sparse
filesystem block for metadata preallocation.

Align the maximum allocation size down to the cluster size to avoid this
situation.

Cc: qemu-stable@nongnu.org
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Disk sizes close to INT64_MAX cause overflow, for some pretty
ridiculous output:

  $ ./nbdkit -U - memory size=$((2**63 - 512)) --run 'qemu-img info $nbd'
  image: nbd+unix://?socket=/tmp/nbdkitHSAzNz/socket
  file format: raw
  virtual size: -8388607T (9223372036854775296 bytes)
  disk size: unavailable

But there's no reason to have two separate implementations of integer
to human-readable abbreviation, where one has overflow and stops at
'T', while the other avoids overflow and goes all the way to 'E'. With
this patch, the output now claims 8EiB instead of -8388607T, which
really is the correct rounding of largest file size supported by qemu
(we could go 511 bytes larger if we used byte-accurate sizing instead
of rounding up to the next sector boundary, but that wouldn't change
the human-readable result).

Quite a few iotests need updates to expected output to match.
Reported-by: NRichard W.M. Jones <rjones@redhat.com>
Signed-off-by: NEric Blake <eblake@redhat.com>
Tested-by: NRichard W.M. Jones <rjones@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Reviewed-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Tested-by: NMax Reitz <mreitz@redhat.com>

When extracting a human-readable size formatter, we changed 'uint64_t
div' pre-patch to 'unsigned long div' post-patch. Which breaks on
32-bit platforms, resulting in 'inf' instead of intended values larger
than 999GB.

Fixes: 22951aaa
CC: qemu-stable@nongnu.org
Reported-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Using IEC binary prefixes in order to make the code more readable,
with the exception of DEFAULT_LOG_SIZE because it's passed to
stringify().
Signed-off-by: NStefano Garzarella <sgarzare@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NJohn Snow <jsnow@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

IEC binary prefixes are already defined in "qemu/units.h",
so we can remove redundant definitions in "block/vhdx.h".
Signed-off-by: NStefano Garzarella <sgarzare@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NJohn Snow <jsnow@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Commit b69864e5 ("vmdk: Support version=3 in VMDK descriptor files")
fixed the probe function to correctly guess vmdk descriptors with
version=3.

This solves the issue where vmdk snapshot with parent vmdk descriptor
containing "version=3" would be treated as raw instead vmdk.

In the future case where a new vmdk version is introduced, we will again
experience this issue, even if the user will provide "-f vmdk" it will
only apply to the tip image and not to the underlying "misprobed" parent
image.

The code in vmdk.c already assumes that the backing file of vmdk must be
vmdk (see vmdk_is_cid_valid which returns 0 if backing file is not
vmdk).

So let's make it official by supplying the backing_format as vmdk.
Reviewed-by: NMark Kanda <mark.kanda@oracle.com>
Reviewed-By: NLiran Alon <liran.alon@oracle.com>
Reviewed-by: NArbel Moshe <arbel.moshe@oracle.com>
Signed-off-by: NShmuel Eiderman <shmuel.eiderman@oracle.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <fam@euphon.net>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Concurrent IO becomes serial IO because of the qemu Coroutine lock,
which reduce IO performance severely.

So unlock Coroutine lock before bdrv_co_pwritev and
bdrv_co_preadv to fix it.
Signed-off-by: NZhengui li <lizhengui@huawei.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Even for block nodes with bs->drv == NULL, we can't just ignore a
bdrv_set_aio_context() call. Leaving the node in its old context can
mean that it's still in an iothread context in bdrv_close_all() during
shutdown, resulting in an attempted unlock of the AioContext lock which
we don't hold.

This is an example stack trace of a related crash:

 #0  0x00007ffff59da57f in raise () at /lib64/libc.so.6
 #1  0x00007ffff59c4895 in abort () at /lib64/libc.so.6
 #2  0x0000555555b97b1e in error_exit (err=<optimized out>, msg=msg@entry=0x555555d386d0 <__func__.19059> "qemu_mutex_unlock_impl") at util/qemu-thread-posix.c:36
 #3  0x0000555555b97f7f in qemu_mutex_unlock_impl (mutex=mutex@entry=0x5555568002f0, file=file@entry=0x555555d378df "util/async.c", line=line@entry=507) at util/qemu-thread-posix.c:97
 #4  0x0000555555b92f55 in aio_context_release (ctx=ctx@entry=0x555556800290) at util/async.c:507
 #5  0x0000555555b05cf8 in bdrv_prwv_co (child=child@entry=0x7fffc80012f0, offset=offset@entry=131072, qiov=qiov@entry=0x7fffffffd4f0, is_write=is_write@entry=true, flags=flags@entry=0)
         at block/io.c:833
 #6  0x0000555555b060a9 in bdrv_pwritev (qiov=0x7fffffffd4f0, offset=131072, child=0x7fffc80012f0) at block/io.c:990
 #7  0x0000555555b060a9 in bdrv_pwrite (child=0x7fffc80012f0, offset=131072, buf=<optimized out>, bytes=<optimized out>) at block/io.c:990
 #8  0x0000555555ae172b in qcow2_cache_entry_flush (bs=bs@entry=0x555556810680, c=c@entry=0x5555568cc740, i=i@entry=0) at block/qcow2-cache.c:51
 #9  0x0000555555ae18dd in qcow2_cache_write (bs=bs@entry=0x555556810680, c=0x5555568cc740) at block/qcow2-cache.c:248
 #10 0x0000555555ae15de in qcow2_cache_flush (bs=0x555556810680, c=<optimized out>) at block/qcow2-cache.c:259
 #11 0x0000555555ae16b1 in qcow2_cache_flush_dependency (c=0x5555568a1700, c=0x5555568a1700, bs=0x555556810680) at block/qcow2-cache.c:194
 #12 0x0000555555ae16b1 in qcow2_cache_entry_flush (bs=bs@entry=0x555556810680, c=c@entry=0x5555568a1700, i=i@entry=0) at block/qcow2-cache.c:194
 #13 0x0000555555ae18dd in qcow2_cache_write (bs=bs@entry=0x555556810680, c=0x5555568a1700) at block/qcow2-cache.c:248
 #14 0x0000555555ae15de in qcow2_cache_flush (bs=bs@entry=0x555556810680, c=<optimized out>) at block/qcow2-cache.c:259
 #15 0x0000555555ad242c in qcow2_inactivate (bs=bs@entry=0x555556810680) at block/qcow2.c:2124
 #16 0x0000555555ad2590 in qcow2_close (bs=0x555556810680) at block/qcow2.c:2153
 #17 0x0000555555ab0c62 in bdrv_close (bs=0x555556810680) at block.c:3358
 #18 0x0000555555ab0c62 in bdrv_delete (bs=0x555556810680) at block.c:3542
 #19 0x0000555555ab0c62 in bdrv_unref (bs=0x555556810680) at block.c:4598
 #20 0x0000555555af4d72 in blk_remove_bs (blk=blk@entry=0x5555568103d0) at block/block-backend.c:785
 #21 0x0000555555af4dbb in blk_remove_all_bs () at block/block-backend.c:483
 #22 0x0000555555aae02f in bdrv_close_all () at block.c:3412
 #23 0x00005555557f9796 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at vl.c:4776

The reproducer I used is a qcow2 image on gluster volume, where the
virtual disk size (4 GB) is larger than the gluster volume size (64M),
so we can easily trigger an ENOSPC. This backend is assigned to a
virtio-blk device using an iothread, and then from the guest a
'dd if=/dev/zero of=/dev/vda bs=1G count=1' causes the VM to stop
because of an I/O error. qemu_gluster_co_flush_to_disk() sets
bs->drv = NULL on error, so when virtio-blk stops the dataplane, the
block nodes stay in the iothread AioContext. A 'quit' monitor command
issued from this paused state crashes the process.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1631227
Cc: qemu-stable@nongnu.org
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>