When draining a block node, we recurse to its parent and for subtree drains also to its children. A single AIO_WAIT_WHILE() is then used to wait for bdrv_drain_poll() to become true, which depends on all of the nodes we recursed to. However, if the respective child or parent becomes quiescent and calls bdrv_wakeup(), only the AioWait of the child/parent is checked, while AIO_WAIT_WHILE() depends on the AioWait of the original node. Fix this by using a single AioWait for all callers of AIO_WAIT_WHILE(). This may mean that the draining thread gets a few more unnecessary wakeups because an unrelated operation got completed, but we already wake it up when something _could_ have changed rather than only if it has certainly changed. Apart from that, drain is a slow path anyway. In theory it would be possible to use wakeups more selectively and still correctly, but the gains are likely not worth the additional complexity. In fact, this patch is a nice simplification for some places in the code. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
168 lines
4.8 KiB
C
168 lines
4.8 KiB
C
/*
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* Declarations for long-running block device operations
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*
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* Copyright (c) 2011 IBM Corp.
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* Copyright (c) 2012 Red Hat, Inc.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#ifndef BLOCKJOB_H
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#define BLOCKJOB_H
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#include "qemu/job.h"
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#include "block/block.h"
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#include "qemu/ratelimit.h"
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#define BLOCK_JOB_SLICE_TIME 100000000ULL /* ns */
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typedef struct BlockJobDriver BlockJobDriver;
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/**
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* BlockJob:
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*
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* Long-running operation on a BlockDriverState.
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*/
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typedef struct BlockJob {
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/** Data belonging to the generic Job infrastructure */
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Job job;
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/** The block device on which the job is operating. */
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BlockBackend *blk;
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/** Status that is published by the query-block-jobs QMP API */
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BlockDeviceIoStatus iostatus;
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/** Speed that was set with @block_job_set_speed. */
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int64_t speed;
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/** Rate limiting data structure for implementing @speed. */
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RateLimit limit;
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/** Block other operations when block job is running */
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Error *blocker;
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/** Called when a cancelled job is finalised. */
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Notifier finalize_cancelled_notifier;
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/** Called when a successfully completed job is finalised. */
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Notifier finalize_completed_notifier;
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/** Called when the job transitions to PENDING */
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Notifier pending_notifier;
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/** Called when the job transitions to READY */
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Notifier ready_notifier;
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/** Called when the job coroutine yields or terminates */
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Notifier idle_notifier;
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/** BlockDriverStates that are involved in this block job */
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GSList *nodes;
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} BlockJob;
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/**
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* block_job_next:
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* @job: A block job, or %NULL.
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*
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* Get the next element from the list of block jobs after @job, or the
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* first one if @job is %NULL.
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*
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* Returns the requested job, or %NULL if there are no more jobs left.
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*/
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BlockJob *block_job_next(BlockJob *job);
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/**
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* block_job_get:
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* @id: The id of the block job.
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*
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* Get the block job identified by @id (which must not be %NULL).
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*
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* Returns the requested job, or %NULL if it doesn't exist.
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*/
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BlockJob *block_job_get(const char *id);
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/**
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* block_job_add_bdrv:
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* @job: A block job
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* @name: The name to assign to the new BdrvChild
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* @bs: A BlockDriverState that is involved in @job
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* @perm, @shared_perm: Permissions to request on the node
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*
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* Add @bs to the list of BlockDriverState that are involved in
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* @job. This means that all operations will be blocked on @bs while
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* @job exists.
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*/
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int block_job_add_bdrv(BlockJob *job, const char *name, BlockDriverState *bs,
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uint64_t perm, uint64_t shared_perm, Error **errp);
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/**
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* block_job_remove_all_bdrv:
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* @job: The block job
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*
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* Remove all BlockDriverStates from the list of nodes that are involved in the
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* job. This removes the blockers added with block_job_add_bdrv().
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*/
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void block_job_remove_all_bdrv(BlockJob *job);
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/**
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* block_job_set_speed:
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* @job: The job to set the speed for.
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* @speed: The new value
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* @errp: Error object.
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*
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* Set a rate-limiting parameter for the job; the actual meaning may
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* vary depending on the job type.
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*/
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void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
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/**
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* block_job_query:
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* @job: The job to get information about.
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*
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* Return information about a job.
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*/
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BlockJobInfo *block_job_query(BlockJob *job, Error **errp);
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/**
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* block_job_iostatus_reset:
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* @job: The job whose I/O status should be reset.
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*
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* Reset I/O status on @job and on BlockDriverState objects it uses,
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* other than job->blk.
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*/
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void block_job_iostatus_reset(BlockJob *job);
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/**
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* block_job_is_internal:
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* @job: The job to determine if it is user-visible or not.
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*
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* Returns true if the job should not be visible to the management layer.
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*/
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bool block_job_is_internal(BlockJob *job);
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/**
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* block_job_driver:
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*
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* Returns the driver associated with a block job.
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*/
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const BlockJobDriver *block_job_driver(BlockJob *job);
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#endif
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