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
  54     /**
  55      * If the callback is not NULL, it will be invoked when all the jobs
  56      * belonging to the same transaction complete; or upon this job's
  57      * completion if it is not in a transaction. Skipped if NULL.
  58      *
  59      * All jobs will complete with a call to either .commit() or .abort() but
  60      * never both.
  61      */
  62     void (*commit)(BlockJob *job);
  63
  64     /**
  65      * If the callback is not NULL, it will be invoked when any job in the
  66      * same transaction fails; or upon this job's failure (due to error or
  67      * cancellation) if it is not in a transaction. Skipped if NULL.
  68      *
  69      * All jobs will complete with a call to either .commit() or .abort() but
  70      * never both.
  71      */
  72     void (*abort)(BlockJob *job);
  73
  74     /**
  75      * If the callback is not NULL, it will be invoked when the job transitions
  76      * into the paused state.  Paused jobs must not perform any asynchronous
  77      * I/O or event loop activity.  This callback is used to quiesce jobs.
  78      */
  79     void coroutine_fn (*pause)(BlockJob *job);
  80
  81     /**
  82      * If the callback is not NULL, it will be invoked when the job transitions
  83      * out of the paused state.  Any asynchronous I/O or event loop activity
  84      * should be restarted from this callback.
  85      */
  86     void coroutine_fn (*resume)(BlockJob *job);
  87
  88     /*
  89      * If the callback is not NULL, it will be invoked before the job is
  90      * resumed in a new AioContext.  This is the place to move any resources
  91      * besides job->blk to the new AioContext.
  92      */
  93     void (*attached_aio_context)(BlockJob *job, AioContext *new_context);
  94 } BlockJobDriver;
  95
  96 /**
  97  * BlockJob:
  98  *
  99  * Long-running operation on a BlockDriverState.
 100  */
 101 struct BlockJob {
 102     /** The job type, including the job vtable.  */
 103     const BlockJobDriver *driver;
 104
 105     /** The block device on which the job is operating.  */
 106     BlockBackend *blk;
 107
 108     /**
 109      * The ID of the block job. Currently the BlockBackend name of the BDS
 110      * owning the job at the time when the job is started.
 111      *
 112      * TODO Decouple block job IDs from BlockBackend names
 113      */
 114     char *id;
 115
 116     /**
 117      * The coroutine that executes the job.  If not NULL, it is
 118      * reentered when busy is false and the job is cancelled.
 119      */
 120     Coroutine *co;
 121
 122     /**
 123      * Set to true if the job should cancel itself.  The flag must
 124      * always be tested just before toggling the busy flag from false
 125      * to true.  After a job has been cancelled, it should only yield
 126      * if #aio_poll will ("sooner or later") reenter the coroutine.
 127      */
 128     bool cancelled;
 129
 130     /**
 131      * Counter for pause request. If non-zero, the block job is either paused,
 132      * or if busy == true will pause itself as soon as possible.
 133      */
 134     int pause_count;
 135
 136     /**
 137      * Set to true if the job is paused by user.  Can be unpaused with the
 138      * block-job-resume QMP command.
 139      */
 140     bool user_paused;
 141
 142     /**
 143      * Set to false by the job while the coroutine has yielded and may be
 144      * re-entered by block_job_enter().  There may still be I/O or event loop
 145      * activity pending.
 146      */
 147     bool busy;
 148
 149     /**
 150      * Set to true by the job while it is in a quiescent state, where
 151      * no I/O or event loop activity is pending.
 152      */
 153     bool paused;
 154
 155     /**
 156      * Set to true when the job is ready to be completed.
 157      */
 158     bool ready;
 159
 160     /**
 161      * Set to true when the job has deferred work to the main loop.
 162      */
 163     bool deferred_to_main_loop;
 164
 165     /** Element of the list of block jobs */
 166     QLIST_ENTRY(BlockJob) job_list;
 167
 168     /** Status that is published by the query-block-jobs QMP API */
 169     BlockDeviceIoStatus iostatus;
 170
 171     /** Offset that is published by the query-block-jobs QMP API */
 172     int64_t offset;
 173
 174     /** Length that is published by the query-block-jobs QMP API */
 175     int64_t len;
 176
 177     /** Speed that was set with @block_job_set_speed.  */
 178     int64_t speed;
 179
 180     /** The completion function that will be called when the job completes.  */
 181     BlockCompletionFunc *cb;
 182
 183     /** Block other operations when block job is running */
 184     Error *blocker;
 185
 186     /** The opaque value that is passed to the completion function.  */
 187     void *opaque;
 188
 189     /** Reference count of the block job */
 190     int refcnt;
 191
 192     /* True if this job has reported completion by calling block_job_completed.
 193      */
 194     bool completed;
 195
 196     /* ret code passed to block_job_completed.
 197      */
 198     int ret;
 199
 200     /** Non-NULL if this job is part of a transaction */
 201     BlockJobTxn *txn;
 202     QLIST_ENTRY(BlockJob) txn_list;
 203 };
 204
 205 /**
 206  * block_job_next:
 207  * @job: A block job, or %NULL.
 208  *
 209  * Get the next element from the list of block jobs after @job, or the
 210  * first one if @job is %NULL.
 211  *
 212  * Returns the requested job, or %NULL if there are no more jobs left.
 213  */
 214 BlockJob *block_job_next(BlockJob *job);
 215
 216 /**
 217  * block_job_create:
 218  * @job_type: The class object for the newly-created job.
 219  * @bs: The block
 220  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 221  * @cb: Completion function for the job.
 222  * @opaque: Opaque pointer value passed to @cb.
 223  * @errp: Error object.
 224  *
 225  * Create a new long-running block device job and return it.  The job
 226  * will call @cb asynchronously when the job completes.  Note that
 227  * @bs may have been closed at the time the @cb it is called.  If
 228  * this is the case, the job may be reported as either cancelled or
 229  * completed.
 230  *
 231  * This function is not part of the public job interface; it should be
 232  * called from a wrapper that is specific to the job type.
 233  */
 234 void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
 235                        int64_t speed, BlockCompletionFunc *cb,
 236                        void *opaque, Error **errp);
 237
 238 /**
 239  * block_job_sleep_ns:
 240  * @job: The job that calls the function.
 241  * @clock: The clock to sleep on.
 242  * @ns: How many nanoseconds to stop for.
 243  *
 244  * Put the job to sleep (assuming that it wasn't canceled) for @ns
 245  * nanoseconds.  Canceling the job will interrupt the wait immediately.
 246  */
 247 void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns);
 248
 249 /**
 250  * block_job_yield:
 251  * @job: The job that calls the function.
 252  *
 253  * Yield the block job coroutine.
 254  */
 255 void block_job_yield(BlockJob *job);
 256
 257 /**
 258  * block_job_ref:
 259  * @bs: The block device.
 260  *
 261  * Grab a reference to the block job. Should be paired with block_job_unref.
 262  */
 263 void block_job_ref(BlockJob *job);
 264
 265 /**
 266  * block_job_unref:
 267  * @bs: The block device.
 268  *
 269  * Release reference to the block job and release resources if it is the last
 270  * reference.
 271  */
 272 void block_job_unref(BlockJob *job);
 273
 274 /**
 275  * block_job_completed:
 276  * @job: The job being completed.
 277  * @ret: The status code.
 278  *
 279  * Call the completion function that was registered at creation time, and
 280  * free @job.
 281  */
 282 void block_job_completed(BlockJob *job, int ret);
 283
 284 /**
 285  * block_job_set_speed:
 286  * @job: The job to set the speed for.
 287  * @speed: The new value
 288  * @errp: Error object.
 289  *
 290  * Set a rate-limiting parameter for the job; the actual meaning may
 291  * vary depending on the job type.
 292  */
 293 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
 294
 295 /**
 296  * block_job_cancel:
 297  * @job: The job to be canceled.
 298  *
 299  * Asynchronously cancel the specified job.
 300  */
 301 void block_job_cancel(BlockJob *job);
 302
 303 /**
 304  * block_job_complete:
 305  * @job: The job to be completed.
 306  * @errp: Error object.
 307  *
 308  * Asynchronously complete the specified job.
 309  */
 310 void block_job_complete(BlockJob *job, Error **errp);
 311
 312 /**
 313  * block_job_is_cancelled:
 314  * @job: The job being queried.
 315  *
 316  * Returns whether the job is scheduled for cancellation.
 317  */
 318 bool block_job_is_cancelled(BlockJob *job);
 319
 320 /**
 321  * block_job_query:
 322  * @job: The job to get information about.
 323  *
 324  * Return information about a job.
 325  */
 326 BlockJobInfo *block_job_query(BlockJob *job);
 327
 328 /**
 329  * block_job_pause_point:
 330  * @job: The job that is ready to pause.
 331  *
 332  * Pause now if block_job_pause() has been called.  Block jobs that perform
 333  * lots of I/O must call this between requests so that the job can be paused.
 334  */
 335 void coroutine_fn block_job_pause_point(BlockJob *job);
 336
 337 /**
 338  * block_job_pause:
 339  * @job: The job to be paused.
 340  *
 341  * Asynchronously pause the specified job.
 342  */
 343 void block_job_pause(BlockJob *job);
 344
 345 /**
 346  * block_job_resume:
 347  * @job: The job to be resumed.
 348  *
 349  * Resume the specified job.  Must be paired with a preceding block_job_pause.
 350  */
 351 void block_job_resume(BlockJob *job);
 352
 353 /**
 354  * block_job_enter:
 355  * @job: The job to enter.
 356  *
 357  * Continue the specified job by entering the coroutine.
 358  */
 359 void block_job_enter(BlockJob *job);
 360
 361 /**
 362  * block_job_event_cancelled:
 363  * @job: The job whose information is requested.
 364  *
 365  * Send a BLOCK_JOB_CANCELLED event for the specified job.
 366  */
 367 void block_job_event_cancelled(BlockJob *job);
 368
 369 /**
 370  * block_job_ready:
 371  * @job: The job which is now ready to complete.
 372  * @msg: Error message. Only present on failure.
 373  *
 374  * Send a BLOCK_JOB_COMPLETED event for the specified job.
 375  */
 376 void block_job_event_completed(BlockJob *job, const char *msg);
 377
 378 /**
 379  * block_job_ready:
 380  * @job: The job which is now ready to complete.
 381  *
 382  * Send a BLOCK_JOB_READY event for the specified job.
 383  */
 384 void block_job_event_ready(BlockJob *job);
 385
 386 /**
 387  * block_job_cancel_sync:
 388  * @job: The job to be canceled.
 389  *
 390  * Synchronously cancel the job.  The completion callback is called
 391  * before the function returns.  The job may actually complete
 392  * instead of canceling itself; the circumstances under which this
 393  * happens depend on the kind of job that is active.
 394  *
 395  * Returns the return value from the job if the job actually completed
 396  * during the call, or -ECANCELED if it was canceled.
 397  */
 398 int block_job_cancel_sync(BlockJob *job);
 399
 400 /**
 401  * block_job_cancel_sync_all:
 402  *
 403  * Synchronously cancels all jobs using block_job_cancel_sync().
 404  */
 405 void block_job_cancel_sync_all(void);
 406
 407 /**
 408  * block_job_complete_sync:
 409  * @job: The job to be completed.
 410  * @errp: Error object which may be set by block_job_complete(); this is not
 411  *        necessarily set on every error, the job return value has to be
 412  *        checked as well.
 413  *
 414  * Synchronously complete the job.  The completion callback is called before the
 415  * function returns, unless it is NULL (which is permissible when using this
 416  * function).
 417  *
 418  * Returns the return value from the job.
 419  */
 420 int block_job_complete_sync(BlockJob *job, Error **errp);
 421
 422 /**
 423  * block_job_iostatus_reset:
 424  * @job: The job whose I/O status should be reset.
 425  *
 426  * Reset I/O status on @job and on BlockDriverState objects it uses,
 427  * other than job->blk.
 428  */
 429 void block_job_iostatus_reset(BlockJob *job);
 430
 431 /**
 432  * block_job_error_action:
 433  * @job: The job to signal an error for.
 434  * @on_err: The error action setting.
 435  * @is_read: Whether the operation was a read.
 436  * @error: The error that was reported.
 437  *
 438  * Report an I/O error for a block job and possibly stop the VM.  Return the
 439  * action that was selected based on @on_err and @error.
 440  */
 441 BlockErrorAction block_job_error_action(BlockJob *job, BlockdevOnError on_err,
 442                                         int is_read, int error);
 443
 444 typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque);
 445
 446 /**
 447  * block_job_defer_to_main_loop:
 448  * @job: The job
 449  * @fn: The function to run in the main loop
 450  * @opaque: The opaque value that is passed to @fn
 451  *
 452  * Execute a given function in the main loop with the BlockDriverState
 453  * AioContext acquired.  Block jobs must call bdrv_unref(), bdrv_close(), and
 454  * anything that uses bdrv_drain_all() in the main loop.
 455  *
 456  * The @job AioContext is held while @fn executes.
 457  */
 458 void block_job_defer_to_main_loop(BlockJob *job,
 459                                   BlockJobDeferToMainLoopFn *fn,
 460                                   void *opaque);
 461
 462 /**
 463  * block_job_txn_new:
 464  *
 465  * Allocate and return a new block job transaction.  Jobs can be added to the
 466  * transaction using block_job_txn_add_job().
 467  *
 468  * The transaction is automatically freed when the last job completes or is
 469  * cancelled.
 470  *
 471  * All jobs in the transaction either complete successfully or fail/cancel as a
 472  * group.  Jobs wait for each other before completing.  Cancelling one job
 473  * cancels all jobs in the transaction.
 474  */
 475 BlockJobTxn *block_job_txn_new(void);
 476
 477 /**
 478  * block_job_txn_unref:
 479  *
 480  * Release a reference that was previously acquired with block_job_txn_add_job
 481  * or block_job_txn_new. If it's the last reference to the object, it will be
 482  * freed.
 483  */
 484 void block_job_txn_unref(BlockJobTxn *txn);
 485
 486 /**
 487  * block_job_txn_add_job:
 488  * @txn: The transaction (may be NULL)
 489  * @job: Job to add to the transaction
 490  *
 491  * Add @job to the transaction.  The @job must not already be in a transaction.
 492  * The caller must call either block_job_txn_unref() or block_job_completed()
 493  * to release the reference that is automatically grabbed here.
 494  */
 495 void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job);
 496
 497 #endif