blockjob.h

   1 /*
   2  * Declarations for long-running block device operations
   3  *
   4  * Copyright (c) 2011 IBM Corp.
   5  * Copyright (c) 2012 Red Hat, Inc.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  */
  25 #ifndef BLOCKJOB_H
  26 #define BLOCKJOB_H 1
  27
  28 #include "block.h"
  29
  30 /**
  31  * BlockJobType:
  32  *
  33  * A class type for block job objects.
  34  */
  35 typedef struct BlockJobType {
  36     /** Derived BlockJob struct size */
  37     size_t instance_size;
  38
  39     /** String describing the operation, part of query-block-jobs QMP API */
  40     const char *job_type;
  41
  42     /** Optional callback for job types that support setting a speed limit */
  43     void (*set_speed)(BlockJob *job, int64_t speed, Error **errp);
  44 } BlockJobType;
  45
  46 /**
  47  * BlockJob:
  48  *
  49  * Long-running operation on a BlockDriverState.
  50  */
  51 struct BlockJob {
  52     /** The job type, including the job vtable.  */
  53     const BlockJobType *job_type;
  54
  55     /** The block device on which the job is operating.  */
  56     BlockDriverState *bs;
  57
  58     /**
  59      * The coroutine that executes the job.  If not NULL, it is
  60      * reentered when busy is false and the job is cancelled.
  61      */
  62     Coroutine *co;
  63
  64     /**
  65      * Set to true if the job should cancel itself.  The flag must
  66      * always be tested just before toggling the busy flag from false
  67      * to true.  After a job has been cancelled, it should only yield
  68      * if #qemu_aio_wait will ("sooner or later") reenter the coroutine.
  69      */
  70     bool cancelled;
  71
  72     /**
  73      * Set to true if the job is either paused, or will pause itself
  74      * as soon as possible (if busy == true).
  75      */
  76     bool paused;
  77
  78     /**
  79      * Set to false by the job while it is in a quiescent state, where
  80      * no I/O is pending and the job has yielded on any condition
  81      * that is not detected by #qemu_aio_wait, such as a timer.
  82      */
  83     bool busy;
  84
  85     /** Offset that is published by the query-block-jobs QMP API */
  86     int64_t offset;
  87
  88     /** Length that is published by the query-block-jobs QMP API */
  89     int64_t len;
  90
  91     /** Speed that was set with @block_job_set_speed.  */
  92     int64_t speed;
  93
  94     /** The completion function that will be called when the job completes.  */
  95     BlockDriverCompletionFunc *cb;
  96
  97     /** The opaque value that is passed to the completion function.  */
  98     void *opaque;
  99 };
 100
 101 /**
 102  * block_job_create:
 103  * @job_type: The class object for the newly-created job.
 104  * @bs: The block
 105  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 106  * @cb: Completion function for the job.
 107  * @opaque: Opaque pointer value passed to @cb.
 108  * @errp: Error object.
 109  *
 110  * Create a new long-running block device job and return it.  The job
 111  * will call @cb asynchronously when the job completes.  Note that
 112  * @bs may have been closed at the time the @cb it is called.  If
 113  * this is the case, the job may be reported as either cancelled or
 114  * completed.
 115  *
 116  * This function is not part of the public job interface; it should be
 117  * called from a wrapper that is specific to the job type.
 118  */
 119 void *block_job_create(const BlockJobType *job_type, BlockDriverState *bs,
 120                        int64_t speed, BlockDriverCompletionFunc *cb,
 121                        void *opaque, Error **errp);
 122
 123 /**
 124  * block_job_sleep_ns:
 125  * @job: The job that calls the function.
 126  * @clock: The clock to sleep on.
 127  * @ns: How many nanoseconds to stop for.
 128  *
 129  * Put the job to sleep (assuming that it wasn't canceled) for @ns
 130  * nanoseconds.  Canceling the job will interrupt the wait immediately.
 131  */
 132 void block_job_sleep_ns(BlockJob *job, QEMUClock *clock, int64_t ns);
 133
 134 /**
 135  * block_job_complete:
 136  * @job: The job being completed.
 137  * @ret: The status code.
 138  *
 139  * Call the completion function that was registered at creation time, and
 140  * free @job.
 141  */
 142 void block_job_complete(BlockJob *job, int ret);
 143
 144 /**
 145  * block_job_set_speed:
 146  * @job: The job to set the speed for.
 147  * @speed: The new value
 148  * @errp: Error object.
 149  *
 150  * Set a rate-limiting parameter for the job; the actual meaning may
 151  * vary depending on the job type.
 152  */
 153 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
 154
 155 /**
 156  * block_job_cancel:
 157  * @job: The job to be canceled.
 158  *
 159  * Asynchronously cancel the specified job.
 160  */
 161 void block_job_cancel(BlockJob *job);
 162
 163 /**
 164  * block_job_is_cancelled:
 165  * @job: The job being queried.
 166  *
 167  * Returns whether the job is scheduled for cancellation.
 168  */
 169 bool block_job_is_cancelled(BlockJob *job);
 170
 171 /**
 172  * block_job_query:
 173  * @job: The job to get information about.
 174  *
 175  * Return information about a job.
 176  */
 177 BlockJobInfo *block_job_query(BlockJob *job);
 178
 179 /**
 180  * block_job_pause:
 181  * @job: The job to be paused.
 182  *
 183  * Asynchronously pause the specified job.
 184  */
 185 void block_job_pause(BlockJob *job);
 186
 187 /**
 188  * block_job_resume:
 189  * @job: The job to be resumed.
 190  *
 191  * Resume the specified job.
 192  */
 193 void block_job_resume(BlockJob *job);
 194
 195 /**
 196  * block_job_is_paused:
 197  * @job: The job being queried.
 198  *
 199  * Returns whether the job is currently paused, or will pause
 200  * as soon as it reaches a sleeping point.
 201  */
 202 bool block_job_is_paused(BlockJob *job);
 203
 204 /**
 205  * block_job_cancel_sync:
 206  * @job: The job to be canceled.
 207  *
 208  * Synchronously cancel the job.  The completion callback is called
 209  * before the function returns.  The job may actually complete
 210  * instead of canceling itself; the circumstances under which this
 211  * happens depend on the kind of job that is active.
 212  *
 213  * Returns the return value from the job if the job actually completed
 214  * during the call, or -ECANCELED if it was canceled.
 215  */
 216 int block_job_cancel_sync(BlockJob *job);
 217
 218 #endif