The following changes since commit 508ba0f7e2092d3ca56e3f75e894d52d8b94818e:

Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20171109' into staging (2017-11-13 11:41:47 +0000)

are available in the git repository at:

git://github.com/stefanha/qemu.git tags/block-pull-request

for you to fetch changes up to 0761562687e0d8135310a94b1d3e08376387c027:

qemu-iotests: Test I/O limits with removable media (2017-11-13 15:46:26 +0000)

The following disk I/O throttling fixes solve recent bugs.

Alberto Garcia (3):

block: Check for inserted BlockDriverState in blk_io_limits_disable()

block: Leave valid throttle timers when removing a BDS from a backend

qemu-iotests: Test I/O limits with removable media

throttle-groups: drain before detaching ThrottleState

Zhengui (1):

block: all I/O should be completed before removing throttle timers.

block/block-backend.c | 36 ++++++++++++++++++---------

block/throttle-groups.c | 6 +++++

tests/qemu-iotests/093 | 62 ++++++++++++++++++++++++++++++++++++++++++++++

tests/qemu-iotests/093.out | 4 +--

4 files changed, 94 insertions(+), 14 deletions(-)

2.13.6

From: Alberto Garcia <berto@igalia.com>

If a BlockBackend has I/O limits set then its ThrottleGroupMember

structure uses the AioContext from its attached BlockDriverState.

Those two contexts must be kept in sync manually. This is not

ideal and will be fixed in the future by removing the throttling

configuration from the BlockBackend and storing it in an implicit

filter node instead, but for now we have to live with this.

When you remove the BlockDriverState from the backend then the

throttle timers are destroyed. If a new BlockDriverState is later

inserted then they are created again using the new AioContext.

There are a couple of problems with this:

a) The code manipulates the timers directly, leaving the

ThrottleGroupMember.aio_context field in an inconsisent state.

b) If you remove the I/O limits (e.g by destroying the backend)

when the timers are gone then throttle_group_unregister_tgm()

will attempt to destroy them again, crashing QEMU.

While b) could be fixed easily by allowing the timers to be freed

twice, this would result in a situation in which we can no longer

guarantee that a valid ThrottleState has a valid AioContext and

timers.

This patch ensures that the timers and AioContext are always valid

when I/O limits are set, regardless of whether the BlockBackend has a

BlockDriverState inserted or not.

[Fixed "There'a" typo as suggested by Max Reitz <mreitz@redhat.com>

block/block-backend.c | 16 ++++++++--------

1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c

--- a/block/block-backend.c

+++ b/block/block-backend.c

@@ -XXX,XX +XXX,XX @@ BlockBackend *blk_by_public(BlockBackendPublic *public)

*/

void blk_remove_bs(BlockBackend *blk)

+ ThrottleGroupMember *tgm = &blk->public.throttle_group_member;

BlockDriverState *bs;

- ThrottleTimers *tt;

notifier_list_notify(&blk->remove_bs_notifiers, blk);

- if (blk->public.throttle_group_member.throttle_state) {

- tt = &blk->public.throttle_group_member.throttle_timers;

+ if (tgm->throttle_state) {

bs = blk_bs(blk);

bdrv_drained_begin(bs);

- throttle_timers_detach_aio_context(tt);

+ throttle_group_detach_aio_context(tgm);

+ throttle_group_attach_aio_context(tgm, qemu_get_aio_context());

bdrv_drained_end(bs);

@@ -XXX,XX +XXX,XX @@ void blk_remove_bs(BlockBackend *blk)

*/

int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp)

{

+ ThrottleGroupMember *tgm = &blk->public.throttle_group_member;

blk->root = bdrv_root_attach_child(bs, "root", &child_root,

blk->perm, blk->shared_perm, blk, errp);

if (blk->root == NULL) {

@@ -XXX,XX +XXX,XX @@ int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp)

bdrv_ref(bs);

notifier_list_notify(&blk->insert_bs_notifiers, blk);

- if (blk->public.throttle_group_member.throttle_state) {

- throttle_timers_attach_aio_context(

- &blk->public.throttle_group_member.throttle_timers,

- bdrv_get_aio_context(bs));

+ if (tgm->throttle_state) {

+ throttle_group_detach_aio_context(tgm);

+ throttle_group_attach_aio_context(tgm, bdrv_get_aio_context(bs));

return 0;

2.13.6

From: Alberto Garcia <berto@igalia.com>

This test hotplugs a CD drive to a VM and checks that I/O limits can

be set only when the drive has media inserted and that they are kept

when the media is replaced.

This also tests the removal of a device with valid I/O limits set but

no media inserted. This involves deleting and disabling the limits

of a BlockBackend without BlockDriverState, a scenario that has been

crashing until the fixes from the last couple of patches.

[Python PEP8 fixup: "Don't use spaces are the = sign when used to

indicate a keyword argument or a default parameter value"

--Stefan]

Signed-off-by: Alberto Garcia <berto@igalia.com>

Reviewed-by: Max Reitz <mreitz@redhat.com>

Message-id: 071eb397118ed207c5a7f01d58766e415ee18d6a.1510339534.git.berto@igalia.com

tests/qemu-iotests/093 | 62 ++++++++++++++++++++++++++++++++++++++++++++++

tests/qemu-iotests/093.out | 4 +--

2 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/tests/qemu-iotests/093 b/tests/qemu-iotests/093

index XXXXXXX..XXXXXXX 100755

--- a/tests/qemu-iotests/093

+++ b/tests/qemu-iotests/093

@@ -XXX,XX +XXX,XX @@ class ThrottleTestGroupNames(iotests.QMPTestCase):

groupname = "group%d" % i

self.verify_name(devname, groupname)

+class ThrottleTestRemovableMedia(iotests.QMPTestCase):

+ def setUp(self):

+ self.vm = iotests.VM()

+ if iotests.qemu_default_machine == 's390-ccw-virtio':

+ self.vm.add_device("virtio-scsi-ccw,id=virtio-scsi")

+ else:

+ self.vm.add_device("virtio-scsi-pci,id=virtio-scsi")

+ self.vm.launch()

+

+ def tearDown(self):

+ self.vm.shutdown()

+

+ def test_removable_media(self):

+ # Add a couple of dummy nodes named cd0 and cd1

+ result = self.vm.qmp("blockdev-add", driver="null-aio",

+ node_name="cd0")

+ self.assert_qmp(result, 'return', {})

+ result = self.vm.qmp("blockdev-add", driver="null-aio",

+ node_name="cd1")

+ self.assert_qmp(result, 'return', {})

+

+ # Attach a CD drive with cd0 inserted

+ result = self.vm.qmp("device_add", driver="scsi-cd",

+ id="dev0", drive="cd0")

+ self.assert_qmp(result, 'return', {})

+

+ # Set I/O limits

+ args = { "id": "dev0", "iops": 100, "iops_rd": 0, "iops_wr": 0,

+ "bps": 50, "bps_rd": 0, "bps_wr": 0 }

+ result = self.vm.qmp("block_set_io_throttle", conv_keys=False, **args)

+ self.assert_qmp(result, 'return', {})

+

+ # Check that the I/O limits have been set

+ result = self.vm.qmp("query-block")

+ self.assert_qmp(result, 'return[0]/inserted/iops', 100)

+ self.assert_qmp(result, 'return[0]/inserted/bps', 50)

+

+ # Now eject cd0 and insert cd1

+ result = self.vm.qmp("blockdev-open-tray", id='dev0')

+ self.assert_qmp(result, 'return', {})

+ result = self.vm.qmp("x-blockdev-remove-medium", id='dev0')

+ self.assert_qmp(result, 'return', {})

+ result = self.vm.qmp("x-blockdev-insert-medium", id='dev0', node_name='cd1')

+ self.assert_qmp(result, 'return', {})

+

+ # Check that the I/O limits are still the same

+ result = self.vm.qmp("query-block")

+ self.assert_qmp(result, 'return[0]/inserted/iops', 100)

+ self.assert_qmp(result, 'return[0]/inserted/bps', 50)

+

+ # Eject cd1

+ result = self.vm.qmp("x-blockdev-remove-medium", id='dev0')

+ self.assert_qmp(result, 'return', {})

+

+ # Check that we can't set limits if the device has no medium

+ result = self.vm.qmp("block_set_io_throttle", conv_keys=False, **args)

+ self.assert_qmp(result, 'error/class', 'GenericError')

+

+ # Remove the CD drive

+ result = self.vm.qmp("device_del", id='dev0')

+ self.assert_qmp(result, 'return', {})

+

if __name__ == '__main__':

iotests.main(supported_fmts=["raw"])

diff --git a/tests/qemu-iotests/093.out b/tests/qemu-iotests/093.out

--- a/tests/qemu-iotests/093.out

+++ b/tests/qemu-iotests/093.out

@@ -XXX,XX +XXX,XX @@

-.......

+........

----------------------------------------------------------------------

-Ran 7 tests

+Ran 8 tests

OK

2.13.6

From: Alberto Garcia <berto@igalia.com>

When you set I/O limits using block_set_io_throttle or the command

line throttling.* options they are kept in the BlockBackend regardless

of whether a BlockDriverState is attached to the backend or not.

Therefore when removing the limits using blk_io_limits_disable() we

need to check if there's a BDS before attempting to drain it, else it

will crash QEMU. This can be reproduced very easily using HMP:

(qemu) drive_add 0 if=none,throttling.iops-total=5000

(qemu) drive_del none0

block/block-backend.c | 14 ++++++++++----

1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c

--- a/block/block-backend.c

+++ b/block/block-backend.c

@@ -XXX,XX +XXX,XX @@ void blk_set_io_limits(BlockBackend *blk, ThrottleConfig *cfg)

void blk_io_limits_disable(BlockBackend *blk)

{

- assert(blk->public.throttle_group_member.throttle_state);

- bdrv_drained_begin(blk_bs(blk));

- throttle_group_unregister_tgm(&blk->public.throttle_group_member);

- bdrv_drained_end(blk_bs(blk));

+ BlockDriverState *bs = blk_bs(blk);

+ ThrottleGroupMember *tgm = &blk->public.throttle_group_member;

+ assert(tgm->throttle_state);

+ if (bs) {

+ bdrv_drained_begin(bs);

+ }

+ throttle_group_unregister_tgm(tgm);

+ if (bs) {

+ bdrv_drained_end(bs);

+ }

2.13.6