qemu/include/block/blockjob.h
Kevin Wolf 8ccb9569a9 blockjob: Store device name at job creation
Some block jobs change the block device graph on completion. This means
that the device that owns the job and originally was addressed with its
device name may no longer be what the corresponding BlockBackend points
to.

Previously, the effects of bdrv_swap() ensured that the job was (at
least partially) transferred to the target image. Events that contain
the device name could still use bdrv_get_device_name(job->bs) and get
the same result.

After removing bdrv_swap(), this won't work any more. Instead, save the
device name at job creation and use that copy for QMP events and
anything else identifying the job.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2015-10-16 15:34:30 +02:00

368 lines
11 KiB
C

/*
* Declarations for long-running block device operations
*
* Copyright (c) 2011 IBM Corp.
* Copyright (c) 2012 Red Hat, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef BLOCKJOB_H
#define BLOCKJOB_H 1
#include "block/block.h"
/**
* BlockJobDriver:
*
* A class type for block job driver.
*/
typedef struct BlockJobDriver {
/** Derived BlockJob struct size */
size_t instance_size;
/** String describing the operation, part of query-block-jobs QMP API */
BlockJobType job_type;
/** Optional callback for job types that support setting a speed limit */
void (*set_speed)(BlockJob *job, int64_t speed, Error **errp);
/** Optional callback for job types that need to forward I/O status reset */
void (*iostatus_reset)(BlockJob *job);
/**
* Optional callback for job types whose completion must be triggered
* manually.
*/
void (*complete)(BlockJob *job, Error **errp);
} BlockJobDriver;
/**
* BlockJob:
*
* Long-running operation on a BlockDriverState.
*/
struct BlockJob {
/** The job type, including the job vtable. */
const BlockJobDriver *driver;
/** The block device on which the job is operating. */
BlockDriverState *bs;
/**
* The ID of the block job. Currently the BlockBackend name of the BDS
* owning the job at the time when the job is started.
*
* TODO Decouple block job IDs from BlockBackend names
*/
char *id;
/**
* The coroutine that executes the job. If not NULL, it is
* reentered when busy is false and the job is cancelled.
*/
Coroutine *co;
/**
* Set to true if the job should cancel itself. The flag must
* always be tested just before toggling the busy flag from false
* to true. After a job has been cancelled, it should only yield
* if #aio_poll will ("sooner or later") reenter the coroutine.
*/
bool cancelled;
/**
* Counter for pause request. If non-zero, the block job is either paused,
* or if busy == true will pause itself as soon as possible.
*/
int pause_count;
/**
* Set to true if the job is paused by user. Can be unpaused with the
* block-job-resume QMP command.
*/
bool user_paused;
/**
* Set to false by the job while it is in a quiescent state, where
* no I/O is pending and the job has yielded on any condition
* that is not detected by #aio_poll, such as a timer.
*/
bool busy;
/**
* Set to true when the job is ready to be completed.
*/
bool ready;
/** Status that is published by the query-block-jobs QMP API */
BlockDeviceIoStatus iostatus;
/** Offset that is published by the query-block-jobs QMP API */
int64_t offset;
/** Length that is published by the query-block-jobs QMP API */
int64_t len;
/** Speed that was set with @block_job_set_speed. */
int64_t speed;
/** The completion function that will be called when the job completes. */
BlockCompletionFunc *cb;
/** Block other operations when block job is running */
Error *blocker;
/** The opaque value that is passed to the completion function. */
void *opaque;
};
/**
* block_job_create:
* @job_type: The class object for the newly-created job.
* @bs: The block
* @speed: The maximum speed, in bytes per second, or 0 for unlimited.
* @cb: Completion function for the job.
* @opaque: Opaque pointer value passed to @cb.
* @errp: Error object.
*
* Create a new long-running block device job and return it. The job
* will call @cb asynchronously when the job completes. Note that
* @bs may have been closed at the time the @cb it is called. If
* this is the case, the job may be reported as either cancelled or
* completed.
*
* This function is not part of the public job interface; it should be
* called from a wrapper that is specific to the job type.
*/
void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
int64_t speed, BlockCompletionFunc *cb,
void *opaque, Error **errp);
/**
* block_job_sleep_ns:
* @job: The job that calls the function.
* @clock: The clock to sleep on.
* @ns: How many nanoseconds to stop for.
*
* Put the job to sleep (assuming that it wasn't canceled) for @ns
* nanoseconds. Canceling the job will interrupt the wait immediately.
*/
void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns);
/**
* block_job_yield:
* @job: The job that calls the function.
*
* Yield the block job coroutine.
*/
void block_job_yield(BlockJob *job);
/**
* block_job_release:
* @bs: The block device.
*
* Release job resources when an error occurred or job completed.
*/
void block_job_release(BlockDriverState *bs);
/**
* block_job_completed:
* @job: The job being completed.
* @ret: The status code.
*
* Call the completion function that was registered at creation time, and
* free @job.
*/
void block_job_completed(BlockJob *job, int ret);
/**
* block_job_set_speed:
* @job: The job to set the speed for.
* @speed: The new value
* @errp: Error object.
*
* Set a rate-limiting parameter for the job; the actual meaning may
* vary depending on the job type.
*/
void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
/**
* block_job_cancel:
* @job: The job to be canceled.
*
* Asynchronously cancel the specified job.
*/
void block_job_cancel(BlockJob *job);
/**
* block_job_complete:
* @job: The job to be completed.
* @errp: Error object.
*
* Asynchronously complete the specified job.
*/
void block_job_complete(BlockJob *job, Error **errp);
/**
* block_job_is_cancelled:
* @job: The job being queried.
*
* Returns whether the job is scheduled for cancellation.
*/
bool block_job_is_cancelled(BlockJob *job);
/**
* block_job_query:
* @job: The job to get information about.
*
* Return information about a job.
*/
BlockJobInfo *block_job_query(BlockJob *job);
/**
* block_job_pause:
* @job: The job to be paused.
*
* Asynchronously pause the specified job.
*/
void block_job_pause(BlockJob *job);
/**
* block_job_resume:
* @job: The job to be resumed.
*
* Resume the specified job. Must be paired with a preceding block_job_pause.
*/
void block_job_resume(BlockJob *job);
/**
* block_job_enter:
* @job: The job to enter.
*
* Continue the specified job by entering the coroutine.
*/
void block_job_enter(BlockJob *job);
/**
* block_job_event_cancelled:
* @job: The job whose information is requested.
*
* Send a BLOCK_JOB_CANCELLED event for the specified job.
*/
void block_job_event_cancelled(BlockJob *job);
/**
* block_job_ready:
* @job: The job which is now ready to complete.
* @msg: Error message. Only present on failure.
*
* Send a BLOCK_JOB_COMPLETED event for the specified job.
*/
void block_job_event_completed(BlockJob *job, const char *msg);
/**
* block_job_ready:
* @job: The job which is now ready to complete.
*
* Send a BLOCK_JOB_READY event for the specified job.
*/
void block_job_event_ready(BlockJob *job);
/**
* block_job_is_paused:
* @job: The job being queried.
*
* Returns whether the job is currently paused, or will pause
* as soon as it reaches a sleeping point.
*/
bool block_job_is_paused(BlockJob *job);
/**
* block_job_cancel_sync:
* @job: The job to be canceled.
*
* Synchronously cancel the job. The completion callback is called
* before the function returns. The job may actually complete
* instead of canceling itself; the circumstances under which this
* happens depend on the kind of job that is active.
*
* Returns the return value from the job if the job actually completed
* during the call, or -ECANCELED if it was canceled.
*/
int block_job_cancel_sync(BlockJob *job);
/**
* block_job_complete_sync:
* @job: The job to be completed.
* @errp: Error object which may be set by block_job_complete(); this is not
* necessarily set on every error, the job return value has to be
* checked as well.
*
* Synchronously complete the job. The completion callback is called before the
* function returns, unless it is NULL (which is permissible when using this
* function).
*
* Returns the return value from the job.
*/
int block_job_complete_sync(BlockJob *job, Error **errp);
/**
* block_job_iostatus_reset:
* @job: The job whose I/O status should be reset.
*
* Reset I/O status on @job and on BlockDriverState objects it uses,
* other than job->bs.
*/
void block_job_iostatus_reset(BlockJob *job);
/**
* block_job_error_action:
* @job: The job to signal an error for.
* @bs: The block device on which to set an I/O error.
* @on_err: The error action setting.
* @is_read: Whether the operation was a read.
* @error: The error that was reported.
*
* Report an I/O error for a block job and possibly stop the VM. Return the
* action that was selected based on @on_err and @error.
*/
BlockErrorAction block_job_error_action(BlockJob *job, BlockDriverState *bs,
BlockdevOnError on_err,
int is_read, int error);
typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque);
/**
* block_job_defer_to_main_loop:
* @job: The job
* @fn: The function to run in the main loop
* @opaque: The opaque value that is passed to @fn
*
* Execute a given function in the main loop with the BlockDriverState
* AioContext acquired. Block jobs must call bdrv_unref(), bdrv_close(), and
* anything that uses bdrv_drain_all() in the main loop.
*
* The @job AioContext is held while @fn executes.
*/
void block_job_defer_to_main_loop(BlockJob *job,
BlockJobDeferToMainLoopFn *fn,
void *opaque);
#endif