Commit Graph

107 Commits

Author SHA1 Message Date
Kevin Wolf 98522f63f4 block: Add errp to bdrv_new()
This patch adds an errp parameter to bdrv_new() and updates all its
callers. The next patches will make use of this in order to check for
duplicate IDs. Most of the callers know that their ID is fine, so they
can simply assert that there is no error.

Behaviour doesn't change with this patch yet as bdrv_new() doesn't
actually assign errors to errp.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
2014-04-22 12:00:20 +02:00
Fam Zheng cd82b6fb4d iscsi: Remember to set ret for iscsi_open in error case
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-04-11 13:59:49 +02:00
Fam Zheng cbee81f6de iscsi: Don't set error if already set in iscsi_do_inquiry
This eliminates the possible assertion failure in error_setg().

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-04-04 14:11:34 +02:00
Paolo Bonzini c97ca29db0 iscsi: always query max WRITE SAME length
Max WRITE SAME length is also used when the UNMAP bit is zero, so it
should be queried even if LBPWS=0.  Same for the optimal transfer
length.

However, the write_zeroes_alignment only matters for UNMAP=1 so we
still restrict it to LBPWS=1.

Reviewed-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-04-03 13:10:53 +02:00
Paolo Bonzini b2f9c08a4f iscsi: ignore flushes on scsi-generic devices
Non-block SCSI devices do not support flushing, but we may still send
them requests via bdrv_flush_all.  Just ignore them.

Reviewed-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-04-03 13:10:45 +02:00
Paolo Bonzini 27898a5daa iscsi: recognize "invalid field" ASCQ from WRITE SAME command
Some targets may return "invalid field" as the ASCQ from WRITE SAME
if they support the command only without the UNMAP field.  Recognize
that, and return ENOTSUP just like for "invalid operation code".

Reviewed-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-04-03 13:10:32 +02:00
Kevin Wolf f47c3f5a80 iscsi: Use bs->sg for everything else than disks
The current iscsi block driver code makes the rather arbitrary decision
that TYPE_MEDIUM_CHANGER and TYPE_TAPE devices have bs->sg = 1 and all
other device types are disks.

Instead of this, check for TYPE_DISK to expose the disk interface and
make everything else bs->sg = 1. In particular, this includes devices
with TYPE_STORAGE_ARRAY, which is what LUN 0 of an iscsi target is.
(See https://bugzilla.redhat.com/show_bug.cgi?id=1067784 for the exact
scenario.)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
2014-03-05 16:58:20 +01:00
Peter Lieven d9738fd246 block/iscsi: fix segfault if writesame fails
commit fa6252b0 introduced a segfault because it tries
to read iTask.task->sense after iTask.task has been
freed.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-02-22 15:59:24 +01:00
Peter Lieven 24d3bd67ac block/iscsi: query for supported VPD pages
this patch ensures that we only query for block provisioning and
block limits vpd pages if they are advertised. It also cleans
up the inquiry code and eliminates some redundant code.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-02-22 10:02:23 +01:00
Peter Lieven 837c390137 block/iscsi: fix deadlock on scsi check condition
the retry logic was broken because the complete status
of the task structure was not reset. this resulted in
an infinite loop retrying the command over and over.

CC: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-02-22 10:02:23 +01:00
Paolo Bonzini f2917853f7 iscsi: correctly propagate errors in iscsi_open
Before:
    $ ./qemu-io-old
    qemu-io-old> open -r -o file.driver=iscsi,file.filename=foo
    Failed to parse URL : foo
    qemu-io-old: can't open device (null): Could not open 'foo': Invalid argument

After:
    $ ./qemu-io
    qemu-io> open -r -o file.driver=iscsi,file.filename=foo
    qemu-io: can't open device (null): Failed to parse URL : foo

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21 21:02:23 +01:00
Paolo Bonzini 35cb1748d5 iscsi: fix indentation
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21 21:02:23 +01:00
Peter Maydell 4c0c9bbe78 Merge remote-tracking branch 'remotes/qmp-unstable/queue/qmp' into staging
* remotes/qmp-unstable/queue/qmp:
  monitor: Add object_add class argument completion.
  monitor: Add object_del id argument completion.
  monitor: Add device_add device argument completion.
  monitor: Add device_del id argument completion.
  qmp: expose list of supported character device backends
  Use error_is_set() only when necessary
  QMP: allow JSON dict arguments in qmp-shell
  hmp: migrate command (without -d) now blocks correctly

Conflicts:
	blockdev.c

[PMM: resolved trivial conflict in blockdev.c]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-02-20 12:10:23 +00:00
Markus Armbruster 84d18f065f Use error_is_set() only when necessary
error_is_set(&var) is the same as var != NULL, but it takes
whole-program analysis to figure that out.  Unnecessarily hard for
optimizers, static checkers, and human readers.  Dumb it down to
obvious.

Gets rid of several dozen Coverity false positives.

Note that the obvious form is already used in many places.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-02-17 11:57:23 -05:00
Jeff Cody 28f106afb3 block: Add notes to iSCSI's .bdrv_open and .bdrv_reopen_prepare
iSCSI currently does not need to do any actions to support the
current usage of bdrv_reopen().  However, it is important to note
a couple of things: 1.) A connection will not be re-established to
an iSCSI target, and 2.) If iscsi_open() is changed to parse 'flags',
then iscsi_reopen_prepare() may need to be more than a stub.

In light of the above, this commit adds comments above both of the
functions to bring attention to these facts.

Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-02-14 13:38:35 +01:00
Peter Lieven 5d259fc7da block/iscsi: always fill bs->bl.opt_transfer_length
the opt_transfer_length has nothing to do with logical
block provisioning stuff so always copy it from
the block limits VPD page.

Reported-By: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-09 09:12:38 +01:00
Anthony Liguori e9f526ab7b Merge remote-tracking branch 'bonzini/scsi-next' into staging
* bonzini/scsi-next:
  scsi: Support TEST UNIT READY in the dummy LUN0
  block: add .bdrv_reopen_prepare() stub for iscsi
  virtio-scsi: Prevent assertion on missed events
  virtio-scsi: Cleanup of I/Os that never started
  scsi: Assign cancel_io vector for scsi_disk_emulate_ops

Conflicts:
	block/iscsi.c

aliguori: resolve trivial merge conflict in block/iscsi.c

Signed-off-by: Anthony Liguori <aliguori@amazon.com>
2014-01-24 15:50:14 -08:00
Paolo Bonzini 2c9880c45e iscsi: Set bs->request_alignment
The iSCSI backend already gets the block size from the READ CAPACITY
command it sends.  Save it so that the generic block layer gets it
too.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
2014-01-24 17:40:03 +01:00
Kevin Wolf d34682cd4a block: Move initialisation of BlockLimits to bdrv_refresh_limits()
This function separates filling the BlockLimits from bdrv_open(), which
allows it to call it from other operations which may change the limits
(e.g. modifications to the backing file chain or bdrv_reopen)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
2014-01-24 17:40:01 +01:00
Peter Lieven 92397116a6 block/iscsi: return -ENOMEM if an async call fails immediately
if an async libiscsi call fails directly it can only be due
to an out of memory condition. All other errors are returned
through the callback.

Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22 12:07:16 +01:00
Jeff Cody dc6afb99b3 block: add .bdrv_reopen_prepare() stub for iscsi
To suppport reopen(), the .bdrv_reopen_prepare() stub must exist.
iSCSI does not have anything that needs to be done to support reopen,
so we can just implement the _prepare() stub.

Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-01-15 10:44:52 +01:00
Edgar E. Iglesias 133fe77437 Merge remote branch 'luiz/queue/qmp' into qmpq
* luiz/queue/qmp:
  migration: qmp_migrate(): keep working after syntax error
  qerror: Remove assert_no_error()
  qemu-option: Remove qemu_opts_create_nofail
  target-i386: Remove assert_no_error usage
  hw: Remove assert_no_error usages
  qdev: Delete dead code
  error: Add error_abort
  monitor: add object-add (QMP) and object_add (HMP) command
  monitor: add object-del (QMP) and object_del (HMP) command
  qom: catch errors in object_property_add_child
  qom: fix leak for objects created with -object
  rng: initialize file descriptor to -1
  qemu-monitor: HMP cpu-add wrapper
  vl: add missing transition debug->finish_migrate

Message-Id: 1389045795-18706-1-git-send-email-lcapitulino@redhat.com
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
2014-01-14 12:10:08 +10:00
Anthony Liguori eedc1a5db5 Merge remote-tracking branch 'bonzini/scsi-next' into staging
* bonzini/scsi-next:
  scsi-disk: add UNMAP limits to block limits VPD page
  block/iscsi: use a bh to schedule co reentrance

Message-id: 1387720926-11421-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Anthony Liguori <aliguori@amazon.com>
2014-01-10 11:05:17 -08:00
Peter Crosthwaite 87ea75d5e1 qemu-option: Remove qemu_opts_create_nofail
This is a boiler-plate _nofail variant of qemu_opts_create. Remove and
use error_abort in call sites.

null/0 arguments needs to be added for the id and fail_if_exists fields
in affected callsites due to argument inconsistency between the normal and
no_fail variants.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-01-06 15:02:30 -05:00
Stefan Weil 219c252193 block/iscsi: Fix compilation for libiscsi 1.4.0 (API change)
Function iscsi_read10_task got additional parameters starting with version
libiscsi 1.5.0.

libiscsi 1.4.0 is still widely used (Debian wheezy, jessie and other Linux
distributions currently provide packages for QEMU which use it), so we
still need support for this older API.

Reviewed-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-12-20 09:11:58 +01:00
Peter Lieven 8b9dfe9098 block/iscsi: use a bh to schedule co reentrance
this fixes a potential segfault and performance regression.

If the coroutine is reentered directly in the iscsi_co_generic_cb
iscsi_process_{read,write} are interrupted and reentered any
time later. One the one hand this could happen after an iscsi_close
where the iscsi context is already gone (segfault). On the
other hand this limits the number of processed callbacks
in each aio_dispatch to one (potential performance regression).

Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-12-16 11:25:51 +01:00
Peter Lieven 063c3378a9 block/iscsi: introduce bdrv_co_{readv, writev, flush_to_disk}
this converts read, write and flush functions from aio to coroutines
eliminating almost 200 lines of code.

The requirement for libiscsi is bumped to version 1.4.0 which was
released in may 2012.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-12-09 11:28:16 +01:00
Peter Lieven 7572ddc8db block/iscsi: set bs->bl.opt_transfer_length
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-12-05 11:45:24 +01:00
Peter Lieven 1c0704a556 block/iscsi: set bdi->cluster_size
this patch aims to set bdi->cluster_size to the internal page size
of the iscsi target so that enabled callers can align requests
properly.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-12-05 11:45:24 +01:00
Paolo Bonzini fa6252b056 block/iscsi: check WRITE SAME support differently depending on MAY_UNMAP
The current check is right for MAY_UNMAP=1.  For MAY_UNMAP=0, just
try and fall back to regular writes as soon as a WRITE SAME command
fails.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-12-03 15:26:49 +01:00
Peter Lieven 2af8a1a704 block/iscsi: updated copyright
added myself to reflect recent work on the iscsi block driver.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-12-03 15:26:49 +01:00
Peter Lieven 4b52498e62 block/iscsi: remove .bdrv_has_zero_init
since commit 3ac21627 the default value changed to 0.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-12-03 15:26:49 +01:00
Peter Lieven d4cd961507 iscsi: add bdrv_co_write_zeroes
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-11-28 10:30:52 +01:00
Peter Lieven 01a6a238a3 iscsi: simplify iscsi_co_discard
now that bdrv_co_discard can handle limits we do not need
the request split logic here anymore.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-11-28 10:30:52 +01:00
Peter Lieven ba6c59191f iscsi: set limits in BlockDriverState
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-11-28 10:30:52 +01:00
Peter Lieven 186d4f2b1d block/iscsi: add .bdrv_get_info
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-11-28 10:30:51 +01:00
Stefan Weil 73f395fa88 misc: New spelling fixes in comments
compatiblity -> compatibility
continously -> continuously
existance -> existence
usefull -> useful
shoudl -> should

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2013-10-26 13:01:57 +04:00
Peter Lieven 24c7608a5d block/iscsi: reenable iscsi_co_get_block_status
Commit f35c934a accidently disabled iscsi_co_get_block_status for all
libiscsi versions. Its not possible to check for enumeration constants
in the C preprocessor. This patch changes the check to the preprocessor
constant LIBISCSI_FEATURE_IOVECTOR which was introduced shortly after
get_lba_status support was added to libiscsi.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-10-09 10:43:42 +02:00
Benoît Canet 030be32184 block: introduce BlockDriver.bdrv_needs_filename to enable some drivers.
Some drivers will have driver specifics options but no filename.
This new bool allow the block layer to treat them correctly.

The .bdrv_needs_filename is set in drivers not having .bdrv_parse_filename and
not having .bdrv_open.

The first exception to this rule will be the quorum driver.

Signed-off-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-09-25 16:21:28 +02:00
Anthony Liguori f3ca508f00 Merge remote-tracking branch 'bonzini/scsi-next' into staging
# By Hervé Poussineau (5) and Stefan Weil (1)
# Via Paolo Bonzini
* bonzini/scsi-next:
  block/iscsi: Drop iscsi_co_get_block_status for older versions of libiscsi
  lsi: add 53C810 variant
  lsi: remove todo
  lsi: ignore write accesses to CTEST0 registers
  lsi: check ssid versus sdid only if ssid is valid
  lsi: use constant name instead of its value
2013-09-23 11:52:32 -05:00
Stefan Weil f35c934a5a block/iscsi: Drop iscsi_co_get_block_status for older versions of libiscsi
Debian wheezy includes libiscsi-dev 1.4.0 which does not provide
SCSI_PROVISIONING_TYPE_DEALLOCATED. Drop iscsi_co_get_block_status
in this case to allow compilation without errors.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-09-18 01:28:50 +02:00
Anthony Liguori 5dc11192b2 Merge remote-tracking branch 'kwolf/for-anthony' into staging
# By Max Reitz (16) and others
# Via Kevin Wolf
* kwolf/for-anthony: (33 commits)
  qemu-iotests: Fix test 038
  block: Assert validity of BdrvActionOps
  qemu-iotests: Cleanup test image in test number 007
  qemu-img: fix invalid JSON
  coroutine: add ./configure --disable-coroutine-pool
  qemu-iotests: Adjustments due to error propagation
  qcow2: Use Error parameter
  qemu-img create: Emit filename on error
  block: Error parameter for create functions
  block: Error parameter for open functions
  bdrv: Use "Error" for creating images
  bdrv: Use "Error" for opening images
  qemu-iotests: add 057 internal snapshot for block device test case
  hmp: add interface hmp_snapshot_delete_blkdev_internal
  hmp: add interface hmp_snapshot_blkdev_internal
  qmp: add interface blockdev-snapshot-delete-internal-sync
  qmp: add interface blockdev-snapshot-internal-sync
  qmp: add internal snapshot support in qmp_transaction
  snapshot: distinguish id and name in snapshot delete
  snapshot: new function bdrv_snapshot_find_by_id_and_name()
  ...

Message-id: 1379073063-14963-1-git-send-email-kwolf@redhat.com
2013-09-17 09:51:40 -05:00
Peter Lieven 65f3e33964 iscsi: split discard requests in multiple parts
Replace .bdrv_aio_discard with .bdrv_co_discard so that discard
requests can be split in multiple parts, each for a small amount
of sectors.

This is useful because we expose a generic API with no limit
on the amount of sectors that can be unmapped in one request.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-09-12 13:14:19 +02:00
Max Reitz d5124c00d8 bdrv: Use "Error" for creating images
Add an Error ** parameter to BlockDriver.bdrv_create to allow more
specific error messages.

Signed-off-by: Max Reitz <mreitz@redhat.com>
2013-09-12 10:12:48 +02:00
Max Reitz 015a1036a7 bdrv: Use "Error" for opening images
Add an Error ** parameter to BlockDriver.bdrv_open and
BlockDriver.bdrv_file_open to allow more specific error messages.

Signed-off-by: Max Reitz <mreitz@redhat.com>
2013-09-12 10:12:47 +02:00
Peter Lieven 54a5c1d5db iscsi: add .bdrv_get_block_status
this patch adds a coroutine for .bdrv_co_block_status as well as
a generic framework that can be used to build coroutines in block/iscsi.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-09-12 08:46:21 +02:00
Peter Lieven f18a7cbb09 iscsi: add logical block provisioning information to iscsilun
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-09-12 08:46:21 +02:00
Paolo Bonzini 5accc8408f scsi: prefer UUID to VM name for the initiator name
The UUID is unique even across multiple hosts, thus it is
better than a VM name even if it is less user-friendly.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-09-12 08:46:21 +02:00
Fam Zheng 4f6fd3491c block: make bdrv_delete() static
Manage BlockDriverState lifecycle with refcnt, so bdrv_delete() is no
longer public and should be called by bdrv_unref() if refcnt is
decreased to 0.

This is an identical change because effectively, there's no multiple
reference of BDS now: no caller of bdrv_ref() yet, only bdrv_new() sets
bs->refcnt to 1, so all bdrv_unref() now actually delete the BDS.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-09-06 15:25:08 +02:00
Fam Zheng 13c91cb7e2 iscsi: use bdrv_new() instead of stack structure
BlockDriverState structure needs bdrv_new() to initialize refcnt, don't
allocate a local structure variable and memset to 0, becasue with coming
refcnt implementation, bdrv_unref will crash if bs->refcnt not
initialized to 1.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-09-06 15:25:08 +02:00