include/block/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/block.h"
  29
  30 /**
  31  * BlockJobDriver:
  32  *
  33  * A class type for block job driver.
  34  */
  35 typedef struct BlockJobDriver {
  36     /** Derived BlockJob struct size */
  37     size_t instance_size;
  38
  39     /** String describing the operation, part of query-block-jobs QMP API */
  40     BlockJobType 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
  45     /** Optional callback for job types that need to forward I/O status reset */
  46     void (*iostatus_reset)(BlockJob *job);
  47
  48     /**
  49      * Optional callback for job types whose completion must be triggered
  50      * manually.
  51      */
  52     void (*complete)(BlockJob *job, Error **errp);
  53 } BlockJobDriver;
  54
  55 /**
  56  * BlockJob:
  57  *
  58  * Long-running operation on a BlockDriverState.
  59  */
  60 struct BlockJob {
  61     /** The job type, including the job vtable.  */
  62     const BlockJobDriver *driver;
  63
  64     /** The block device on which the job is operating.  */
  65     BlockDriverState *bs;
  66
  67     /**
  68      * The coroutine that executes the job.  If not NULL, it is
  69      * reentered when busy is false and the job is cancelled.
  70      */
  71     Coroutine *co;
  72
  73     /**
  74      * Set to true if the job should cancel itself.  The flag must
  75      * always be tested just before toggling the busy flag from false
  76      * to true.  After a job has been cancelled, it should only yield
  77      * if #aio_poll will ("sooner or later") reenter the coroutine.
  78      */
  79     bool cancelled;
  80
  81     /**
  82      * Counter for pause request. If non-zero, the block job is either paused,
  83      * or if busy == true will pause itself as soon as possible.
  84      */
  85     int pause_count;
  86
  87     /**
  88      * Set to true if the job is paused by user.  Can be unpaused with the
  89      * block-job-resume QMP command.
  90      */
  91     bool user_paused;
  92
  93     /**
  94      * Set to false by the job while it is in a quiescent state, where
  95      * no I/O is pending and the job has yielded on any condition
  96      * that is not detected by #aio_poll, such as a timer.
  97      */
  98     bool busy;
  99
 100     /**
 101      * Set to true when the job is ready to be completed.
 102      */
 103     bool ready;
 104
 105     /** Status that is published by the query-block-jobs QMP API */
 106     BlockDeviceIoStatus iostatus;
 107
 108     /** Offset that is published by the query-block-jobs QMP API */
 109     int64_t offset;
 110
 111     /** Length that is published by the query-block-jobs QMP API */
 112     int64_t len;
 113
 114     /** Speed that was set with @block_job_set_speed.  */
 115     int64_t speed;
 116
 117     /** The completion function that will be called when the job completes.  */
 118     BlockCompletionFunc *cb;
 119
 120     /** Block other operations when block job is running */
 121     Error *blocker;
 122
 123     /** The opaque value that is passed to the completion function.  */
 124     void *opaque;
 125 };
 126
 127 /**
 128  * block_job_create:
 129  * @job_type: The class object for the newly-created job.
 130  * @bs: The block
 131  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 132  * @cb: Completion function for the job.
 133  * @opaque: Opaque pointer value passed to @cb.
 134  * @errp: Error object.
 135  *
 136  * Create a new long-running block device job and return it.  The job
 137  * will call @cb asynchronously when the job completes.  Note that
 138  * @bs may have been closed at the time the @cb it is called.  If
 139  * this is the case, the job may be reported as either cancelled or
 140  * completed.
 141  *
 142  * This function is not part of the public job interface; it should be
 143  * called from a wrapper that is specific to the job type.
 144  */
 145 void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
 146                        int64_t speed, BlockCompletionFunc *cb,
 147                        void *opaque, Error **errp);
 148
 149 /**
 150  * block_job_sleep_ns:
 151  * @job: The job that calls the function.
 152  * @clock: The clock to sleep on.
 153  * @ns: How many nanoseconds to stop for.
 154  *
 155  * Put the job to sleep (assuming that it wasn't canceled) for @ns
 156  * nanoseconds.  Canceling the job will interrupt the wait immediately.
 157  */
 158 void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns);
 159
 160 /**
 161  * block_job_yield:
 162  * @job: The job that calls the function.
 163  *
 164  * Yield the block job coroutine.
 165  */
 166 void block_job_yield(BlockJob *job);
 167
 168 /**
 169  * block_job_release:
 170  * @bs: The block device.
 171  *
 172  * Release job resources when an error occurred or job completed.
 173  */
 174 void block_job_release(BlockDriverState *bs);
 175
 176 /**
 177  * block_job_completed:
 178  * @job: The job being completed.
 179  * @ret: The status code.
 180  *
 181  * Call the completion function that was registered at creation time, and
 182  * free @job.
 183  */
 184 void block_job_completed(BlockJob *job, int ret);
 185
 186 /**
 187  * block_job_set_speed:
 188  * @job: The job to set the speed for.
 189  * @speed: The new value
 190  * @errp: Error object.
 191  *
 192  * Set a rate-limiting parameter for the job; the actual meaning may
 193  * vary depending on the job type.
 194  */
 195 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
 196
 197 /**
 198  * block_job_cancel:
 199  * @job: The job to be canceled.
 200  *
 201  * Asynchronously cancel the specified job.
 202  */
 203 void block_job_cancel(BlockJob *job);
 204
 205 /**
 206  * block_job_complete:
 207  * @job: The job to be completed.
 208  * @errp: Error object.
 209  *
 210  * Asynchronously complete the specified job.
 211  */
 212 void block_job_complete(BlockJob *job, Error **errp);
 213
 214 /**
 215  * block_job_is_cancelled:
 216  * @job: The job being queried.
 217  *
 218  * Returns whether the job is scheduled for cancellation.
 219  */
 220 bool block_job_is_cancelled(BlockJob *job);
 221
 222 /**
 223  * block_job_query:
 224  * @job: The job to get information about.
 225  *
 226  * Return information about a job.
 227  */
 228 BlockJobInfo *block_job_query(BlockJob *job);
 229
 230 /**
 231  * block_job_pause:
 232  * @job: The job to be paused.
 233  *
 234  * Asynchronously pause the specified job.
 235  */
 236 void block_job_pause(BlockJob *job);
 237
 238 /**
 239  * block_job_resume:
 240  * @job: The job to be resumed.
 241  *
 242  * Resume the specified job.  Must be paired with a preceding block_job_pause.
 243  */
 244 void block_job_resume(BlockJob *job);
 245
 246 /**
 247  * block_job_enter:
 248  * @job: The job to enter.
 249  *
 250  * Continue the specified job by entering the coroutine.
 251  */
 252 void block_job_enter(BlockJob *job);
 253
 254 /**
 255  * block_job_event_cancelled:
 256  * @job: The job whose information is requested.
 257  *
 258  * Send a BLOCK_JOB_CANCELLED event for the specified job.
 259  */
 260 void block_job_event_cancelled(BlockJob *job);
 261
 262 /**
 263  * block_job_ready:
 264  * @job: The job which is now ready to complete.
 265  * @msg: Error message. Only present on failure.
 266  *
 267  * Send a BLOCK_JOB_COMPLETED event for the specified job.
 268  */
 269 void block_job_event_completed(BlockJob *job, const char *msg);
 270
 271 /**
 272  * block_job_ready:
 273  * @job: The job which is now ready to complete.
 274  *
 275  * Send a BLOCK_JOB_READY event for the specified job.
 276  */
 277 void block_job_event_ready(BlockJob *job);
 278
 279 /**
 280  * block_job_is_paused:
 281  * @job: The job being queried.
 282  *
 283  * Returns whether the job is currently paused, or will pause
 284  * as soon as it reaches a sleeping point.
 285  */
 286 bool block_job_is_paused(BlockJob *job);
 287
 288 /**
 289  * block_job_cancel_sync:
 290  * @job: The job to be canceled.
 291  *
 292  * Synchronously cancel the job.  The completion callback is called
 293  * before the function returns.  The job may actually complete
 294  * instead of canceling itself; the circumstances under which this
 295  * happens depend on the kind of job that is active.
 296  *
 297  * Returns the return value from the job if the job actually completed
 298  * during the call, or -ECANCELED if it was canceled.
 299  */
 300 int block_job_cancel_sync(BlockJob *job);
 301
 302 /**
 303  * block_job_complete_sync:
 304  * @job: The job to be completed.
 305  * @errp: Error object which may be set by block_job_complete(); this is not
 306  *        necessarily set on every error, the job return value has to be
 307  *        checked as well.
 308  *
 309  * Synchronously complete the job.  The completion callback is called before the
 310  * function returns, unless it is NULL (which is permissible when using this
 311  * function).
 312  *
 313  * Returns the return value from the job.
 314  */
 315 int block_job_complete_sync(BlockJob *job, Error **errp);
 316
 317 /**
 318  * block_job_iostatus_reset:
 319  * @job: The job whose I/O status should be reset.
 320  *
 321  * Reset I/O status on @job and on BlockDriverState objects it uses,
 322  * other than job->bs.
 323  */
 324 void block_job_iostatus_reset(BlockJob *job);
 325
 326 /**
 327  * block_job_error_action:
 328  * @job: The job to signal an error for.
 329  * @bs: The block device on which to set an I/O error.
 330  * @on_err: The error action setting.
 331  * @is_read: Whether the operation was a read.
 332  * @error: The error that was reported.
 333  *
 334  * Report an I/O error for a block job and possibly stop the VM.  Return the
 335  * action that was selected based on @on_err and @error.
 336  */
 337 BlockErrorAction block_job_error_action(BlockJob *job, BlockDriverState *bs,
 338                                         BlockdevOnError on_err,
 339                                         int is_read, int error);
 340
 341 typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque);
 342
 343 /**
 344  * block_job_defer_to_main_loop:
 345  * @job: The job
 346  * @fn: The function to run in the main loop
 347  * @opaque: The opaque value that is passed to @fn
 348  *
 349  * Execute a given function in the main loop with the BlockDriverState
 350  * AioContext acquired.  Block jobs must call bdrv_unref(), bdrv_close(), and
 351  * anything that uses bdrv_drain_all() in the main loop.
 352  *
 353  * The @job AioContext is held while @fn executes.
 354  */
 355 void block_job_defer_to_main_loop(BlockJob *job,
 356                                   BlockJobDeferToMainLoopFn *fn,
 357                                   void *opaque);
 358
 359 #endif