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 ID of the block job. Currently the BlockBackend name of the BDS
  69      * owning the job at the time when the job is started.
  70      *
  71      * TODO Decouple block job IDs from BlockBackend names
  72      */
  73     char *id;
  74
  75     /**
  76      * The coroutine that executes the job.  If not NULL, it is
  77      * reentered when busy is false and the job is cancelled.
  78      */
  79     Coroutine *co;
  80
  81     /**
  82      * Set to true if the job should cancel itself.  The flag must
  83      * always be tested just before toggling the busy flag from false
  84      * to true.  After a job has been cancelled, it should only yield
  85      * if #aio_poll will ("sooner or later") reenter the coroutine.
  86      */
  87     bool cancelled;
  88
  89     /**
  90      * Counter for pause request. If non-zero, the block job is either paused,
  91      * or if busy == true will pause itself as soon as possible.
  92      */
  93     int pause_count;
  94
  95     /**
  96      * Set to true if the job is paused by user.  Can be unpaused with the
  97      * block-job-resume QMP command.
  98      */
  99     bool user_paused;
 100
 101     /**
 102      * Set to false by the job while it is in a quiescent state, where
 103      * no I/O is pending and the job has yielded on any condition
 104      * that is not detected by #aio_poll, such as a timer.
 105      */
 106     bool busy;
 107
 108     /**
 109      * Set to true when the job is ready to be completed.
 110      */
 111     bool ready;
 112
 113     /** Status that is published by the query-block-jobs QMP API */
 114     BlockDeviceIoStatus iostatus;
 115
 116     /** Offset that is published by the query-block-jobs QMP API */
 117     int64_t offset;
 118
 119     /** Length that is published by the query-block-jobs QMP API */
 120     int64_t len;
 121
 122     /** Speed that was set with @block_job_set_speed.  */
 123     int64_t speed;
 124
 125     /** The completion function that will be called when the job completes.  */
 126     BlockCompletionFunc *cb;
 127
 128     /** Block other operations when block job is running */
 129     Error *blocker;
 130
 131     /** The opaque value that is passed to the completion function.  */
 132     void *opaque;
 133 };
 134
 135 /**
 136  * block_job_create:
 137  * @job_type: The class object for the newly-created job.
 138  * @bs: The block
 139  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 140  * @cb: Completion function for the job.
 141  * @opaque: Opaque pointer value passed to @cb.
 142  * @errp: Error object.
 143  *
 144  * Create a new long-running block device job and return it.  The job
 145  * will call @cb asynchronously when the job completes.  Note that
 146  * @bs may have been closed at the time the @cb it is called.  If
 147  * this is the case, the job may be reported as either cancelled or
 148  * completed.
 149  *
 150  * This function is not part of the public job interface; it should be
 151  * called from a wrapper that is specific to the job type.
 152  */
 153 void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
 154                        int64_t speed, BlockCompletionFunc *cb,
 155                        void *opaque, Error **errp);
 156
 157 /**
 158  * block_job_sleep_ns:
 159  * @job: The job that calls the function.
 160  * @clock: The clock to sleep on.
 161  * @ns: How many nanoseconds to stop for.
 162  *
 163  * Put the job to sleep (assuming that it wasn't canceled) for @ns
 164  * nanoseconds.  Canceling the job will interrupt the wait immediately.
 165  */
 166 void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns);
 167
 168 /**
 169  * block_job_yield:
 170  * @job: The job that calls the function.
 171  *
 172  * Yield the block job coroutine.
 173  */
 174 void block_job_yield(BlockJob *job);
 175
 176 /**
 177  * block_job_release:
 178  * @bs: The block device.
 179  *
 180  * Release job resources when an error occurred or job completed.
 181  */
 182 void block_job_release(BlockDriverState *bs);
 183
 184 /**
 185  * block_job_completed:
 186  * @job: The job being completed.
 187  * @ret: The status code.
 188  *
 189  * Call the completion function that was registered at creation time, and
 190  * free @job.
 191  */
 192 void block_job_completed(BlockJob *job, int ret);
 193
 194 /**
 195  * block_job_set_speed:
 196  * @job: The job to set the speed for.
 197  * @speed: The new value
 198  * @errp: Error object.
 199  *
 200  * Set a rate-limiting parameter for the job; the actual meaning may
 201  * vary depending on the job type.
 202  */
 203 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
 204
 205 /**
 206  * block_job_cancel:
 207  * @job: The job to be canceled.
 208  *
 209  * Asynchronously cancel the specified job.
 210  */
 211 void block_job_cancel(BlockJob *job);
 212
 213 /**
 214  * block_job_complete:
 215  * @job: The job to be completed.
 216  * @errp: Error object.
 217  *
 218  * Asynchronously complete the specified job.
 219  */
 220 void block_job_complete(BlockJob *job, Error **errp);
 221
 222 /**
 223  * block_job_is_cancelled:
 224  * @job: The job being queried.
 225  *
 226  * Returns whether the job is scheduled for cancellation.
 227  */
 228 bool block_job_is_cancelled(BlockJob *job);
 229
 230 /**
 231  * block_job_query:
 232  * @job: The job to get information about.
 233  *
 234  * Return information about a job.
 235  */
 236 BlockJobInfo *block_job_query(BlockJob *job);
 237
 238 /**
 239  * block_job_pause:
 240  * @job: The job to be paused.
 241  *
 242  * Asynchronously pause the specified job.
 243  */
 244 void block_job_pause(BlockJob *job);
 245
 246 /**
 247  * block_job_resume:
 248  * @job: The job to be resumed.
 249  *
 250  * Resume the specified job.  Must be paired with a preceding block_job_pause.
 251  */
 252 void block_job_resume(BlockJob *job);
 253
 254 /**
 255  * block_job_enter:
 256  * @job: The job to enter.
 257  *
 258  * Continue the specified job by entering the coroutine.
 259  */
 260 void block_job_enter(BlockJob *job);
 261
 262 /**
 263  * block_job_event_cancelled:
 264  * @job: The job whose information is requested.
 265  *
 266  * Send a BLOCK_JOB_CANCELLED event for the specified job.
 267  */
 268 void block_job_event_cancelled(BlockJob *job);
 269
 270 /**
 271  * block_job_ready:
 272  * @job: The job which is now ready to complete.
 273  * @msg: Error message. Only present on failure.
 274  *
 275  * Send a BLOCK_JOB_COMPLETED event for the specified job.
 276  */
 277 void block_job_event_completed(BlockJob *job, const char *msg);
 278
 279 /**
 280  * block_job_ready:
 281  * @job: The job which is now ready to complete.
 282  *
 283  * Send a BLOCK_JOB_READY event for the specified job.
 284  */
 285 void block_job_event_ready(BlockJob *job);
 286
 287 /**
 288  * block_job_is_paused:
 289  * @job: The job being queried.
 290  *
 291  * Returns whether the job is currently paused, or will pause
 292  * as soon as it reaches a sleeping point.
 293  */
 294 bool block_job_is_paused(BlockJob *job);
 295
 296 /**
 297  * block_job_cancel_sync:
 298  * @job: The job to be canceled.
 299  *
 300  * Synchronously cancel the job.  The completion callback is called
 301  * before the function returns.  The job may actually complete
 302  * instead of canceling itself; the circumstances under which this
 303  * happens depend on the kind of job that is active.
 304  *
 305  * Returns the return value from the job if the job actually completed
 306  * during the call, or -ECANCELED if it was canceled.
 307  */
 308 int block_job_cancel_sync(BlockJob *job);
 309
 310 /**
 311  * block_job_complete_sync:
 312  * @job: The job to be completed.
 313  * @errp: Error object which may be set by block_job_complete(); this is not
 314  *        necessarily set on every error, the job return value has to be
 315  *        checked as well.
 316  *
 317  * Synchronously complete the job.  The completion callback is called before the
 318  * function returns, unless it is NULL (which is permissible when using this
 319  * function).
 320  *
 321  * Returns the return value from the job.
 322  */
 323 int block_job_complete_sync(BlockJob *job, Error **errp);
 324
 325 /**
 326  * block_job_iostatus_reset:
 327  * @job: The job whose I/O status should be reset.
 328  *
 329  * Reset I/O status on @job and on BlockDriverState objects it uses,
 330  * other than job->bs.
 331  */
 332 void block_job_iostatus_reset(BlockJob *job);
 333
 334 /**
 335  * block_job_error_action:
 336  * @job: The job to signal an error for.
 337  * @bs: The block device on which to set an I/O error.
 338  * @on_err: The error action setting.
 339  * @is_read: Whether the operation was a read.
 340  * @error: The error that was reported.
 341  *
 342  * Report an I/O error for a block job and possibly stop the VM.  Return the
 343  * action that was selected based on @on_err and @error.
 344  */
 345 BlockErrorAction block_job_error_action(BlockJob *job, BlockDriverState *bs,
 346                                         BlockdevOnError on_err,
 347                                         int is_read, int error);
 348
 349 typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque);
 350
 351 /**
 352  * block_job_defer_to_main_loop:
 353  * @job: The job
 354  * @fn: The function to run in the main loop
 355  * @opaque: The opaque value that is passed to @fn
 356  *
 357  * Execute a given function in the main loop with the BlockDriverState
 358  * AioContext acquired.  Block jobs must call bdrv_unref(), bdrv_close(), and
 359  * anything that uses bdrv_drain_all() in the main loop.
 360  *
 361  * The @job AioContext is held while @fn executes.
 362  */
 363 void block_job_defer_to_main_loop(BlockJob *job,
 364                                   BlockJobDeferToMainLoopFn *fn,
 365                                   void *opaque);
 366
 367 #endif