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block: Replace in_use with operation blocker

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This drops BlockDriverState.in_use with op_blockers:

  - Call bdrv_op_block_all in place of bdrv_set_in_use(bs, 1).

  - Call bdrv_op_unblock_all in place of bdrv_set_in_use(bs, 0).

  - Check bdrv_op_is_blocked() in place of bdrv_in_use(bs).

    The specific types are used, e.g. in place of starting block backup,
    bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP, ...).

    There is one exception in block_job_create, where
    bdrv_op_blocker_is_empty() is used, because we don't know the operation
    type here. This doesn't matter because in a few commits away we will drop
    the check and move it to callers that _do_ know the type.

  - Check bdrv_op_blocker_is_empty() in place of assert(!bs->in_use).

Note: there is only bdrv_op_block_all and bdrv_op_unblock_all callers at
this moment. So although the checks are specific to op types, this
changes can still be seen as identical logic with previously with
in_use. The difference is error message are improved because of blocker
error info.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Fam Zheng 2014-05-23 21:29:43 +08:00 • committed by Stefan Hajnoczi
parent fbe40ff780
commit 3718d8ab65
8 changed files with 45 additions and 43 deletions
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18
hw/block/dataplane/virtio-blk.c
View file

@ -70,6 +70,9 @@ struct VirtIOBlockDataPlane {
queue */
unsigned int num_reqs;
/* Operation blocker on BDS */
Error *blocker;
};
/* Raise an interrupt to signal guest, if necessary */
@ -350,6 +353,7 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
{
VirtIOBlockDataPlane *s;
int fd;
Error *local_err = NULL;
*dataplane = NULL;
@ -372,9 +376,10 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
/* If dataplane is (re-)enabled while the guest is running there could be
* block jobs that can conflict.
*/
if (bdrv_in_use(blk->conf.bs)) {
error_setg(errp,
"cannot start dataplane thread while device is in use");
if (bdrv_op_is_blocked(blk->conf.bs, BLOCK_OP_TYPE_DATAPLANE, &local_err)) {
error_report("cannot start dataplane thread: %s",
error_get_pretty(local_err));
error_free(local_err);
return;
}
@ -406,8 +411,8 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
}
s->ctx = iothread_get_aio_context(s->iothread);
/* Prevent block operations that conflict with data plane thread */
bdrv_set_in_use(blk->conf.bs, 1);
error_setg(&s->blocker, "block device is in use by data plane");
bdrv_op_block_all(blk->conf.bs, s->blocker);
*dataplane = s;
}
@ -420,7 +425,8 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
}
virtio_blk_data_plane_stop(s);
bdrv_set_in_use(s->blk->conf.bs, 0);
bdrv_op_unblock_all(s->blk->conf.bs, s->blocker);
error_free(s->blocker);
object_unref(OBJECT(s->iothread));
g_free(s);
}