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
  26 #ifndef BLOCKJOB_H
  27 #define BLOCKJOB_H
  28
  29 #include "block/block.h"
  30
  31 /**
  32  * BlockJobDriver:
  33  *
  34  * A class type for block job driver.
  35  */
  36 typedef struct BlockJobDriver {
  37     /** Derived BlockJob struct size */
  38     size_t instance_size;
  39
  40     /** String describing the operation, part of query-block-jobs QMP API */
  41     BlockJobType job_type;
  42
  43     /** Optional callback for job types that support setting a speed limit */
  44     void (*set_speed)(BlockJob *job, int64_t speed, Error **errp);
  45
  46     /** Optional callback for job types that need to forward I/O status reset */
  47     void (*iostatus_reset)(BlockJob *job);
  48
  49     /**
  50      * Optional callback for job types whose completion must be triggered
  51      * manually.
  52      */
  53     void (*complete)(BlockJob *job, Error **errp);
  54
  55     /**
  56      * If the callback is not NULL, it will be invoked when all the jobs
  57      * belonging to the same transaction complete; or upon this job's
  58      * completion if it is not in a transaction. Skipped if NULL.
  59      *
  60      * All jobs will complete with a call to either .commit() or .abort() but
  61      * never both.
  62      */
  63     void (*commit)(BlockJob *job);
  64
  65     /**
  66      * If the callback is not NULL, it will be invoked when any job in the
  67      * same transaction fails; or upon this job's failure (due to error or
  68      * cancellation) if it is not in a transaction. Skipped if NULL.
  69      *
  70      * All jobs will complete with a call to either .commit() or .abort() but
  71      * never both.
  72      */
  73     void (*abort)(BlockJob *job);
  74
  75     /**
  76      * If the callback is not NULL, it will be invoked when the job transitions
  77      * into the paused state.  Paused jobs must not perform any asynchronous
  78      * I/O or event loop activity.  This callback is used to quiesce jobs.
  79      */
  80     void coroutine_fn (*pause)(BlockJob *job);
  81
  82     /**
  83      * If the callback is not NULL, it will be invoked when the job transitions
  84      * out of the paused state.  Any asynchronous I/O or event loop activity
  85      * should be restarted from this callback.
  86      */
  87     void coroutine_fn (*resume)(BlockJob *job);
  88
  89     /*
  90      * If the callback is not NULL, it will be invoked before the job is
  91      * resumed in a new AioContext.  This is the place to move any resources
  92      * besides job->blk to the new AioContext.
  93      */
  94     void (*attached_aio_context)(BlockJob *job, AioContext *new_context);
  95
  96     /*
  97      * If the callback is not NULL, it will be invoked when the job has to be
  98      * synchronously cancelled or completed; it should drain BlockDriverStates
  99      * as required to ensure progress.
 100      */
 101     void (*drain)(BlockJob *job);
 102 } BlockJobDriver;
 103
 104 /**
 105  * BlockJob:
 106  *
 107  * Long-running operation on a BlockDriverState.
 108  */
 109 struct BlockJob {
 110     /** The job type, including the job vtable.  */
 111     const BlockJobDriver *driver;
 112
 113     /** The block device on which the job is operating.  */
 114     BlockBackend *blk;
 115
 116     /**
 117      * The ID of the block job.
 118      */
 119     char *id;
 120
 121     /**
 122      * The coroutine that executes the job.  If not NULL, it is
 123      * reentered when busy is false and the job is cancelled.
 124      */
 125     Coroutine *co;
 126
 127     /**
 128      * Set to true if the job should cancel itself.  The flag must
 129      * always be tested just before toggling the busy flag from false
 130      * to true.  After a job has been cancelled, it should only yield
 131      * if #aio_poll will ("sooner or later") reenter the coroutine.
 132      */
 133     bool cancelled;
 134
 135     /**
 136      * Counter for pause request. If non-zero, the block job is either paused,
 137      * or if busy == true will pause itself as soon as possible.
 138      */
 139     int pause_count;
 140
 141     /**
 142      * Set to true if the job is paused by user.  Can be unpaused with the
 143      * block-job-resume QMP command.
 144      */
 145     bool user_paused;
 146
 147     /**
 148      * Set to false by the job while the coroutine has yielded and may be
 149      * re-entered by block_job_enter().  There may still be I/O or event loop
 150      * activity pending.
 151      */
 152     bool busy;
 153
 154     /**
 155      * Set to true by the job while it is in a quiescent state, where
 156      * no I/O or event loop activity is pending.
 157      */
 158     bool paused;
 159
 160     /**
 161      * Set to true when the job is ready to be completed.
 162      */
 163     bool ready;
 164
 165     /**
 166      * Set to true when the job has deferred work to the main loop.
 167      */
 168     bool deferred_to_main_loop;
 169
 170     /** Element of the list of block jobs */
 171     QLIST_ENTRY(BlockJob) job_list;
 172
 173     /** Status that is published by the query-block-jobs QMP API */
 174     BlockDeviceIoStatus iostatus;
 175
 176     /** Offset that is published by the query-block-jobs QMP API */
 177     int64_t offset;
 178
 179     /** Length that is published by the query-block-jobs QMP API */
 180     int64_t len;
 181
 182     /** Speed that was set with @block_job_set_speed.  */
 183     int64_t speed;
 184
 185     /** The completion function that will be called when the job completes.  */
 186     BlockCompletionFunc *cb;
 187
 188     /** Block other operations when block job is running */
 189     Error *blocker;
 190
 191     /** BlockDriverStates that are involved in this block job */
 192     GSList *nodes;
 193
 194     /** The opaque value that is passed to the completion function.  */
 195     void *opaque;
 196
 197     /** Reference count of the block job */
 198     int refcnt;
 199
 200     /* True if this job has reported completion by calling block_job_completed.
 201      */
 202     bool completed;
 203
 204     /* ret code passed to block_job_completed.
 205      */
 206     int ret;
 207
 208     /** Non-NULL if this job is part of a transaction */
 209     BlockJobTxn *txn;
 210     QLIST_ENTRY(BlockJob) txn_list;
 211 };
 212
 213 /**
 214  * block_job_next:
 215  * @job: A block job, or %NULL.
 216  *
 217  * Get the next element from the list of block jobs after @job, or the
 218  * first one if @job is %NULL.
 219  *
 220  * Returns the requested job, or %NULL if there are no more jobs left.
 221  */
 222 BlockJob *block_job_next(BlockJob *job);
 223
 224 /**
 225  * block_job_get:
 226  * @id: The id of the block job.
 227  *
 228  * Get the block job identified by @id (which must not be %NULL).
 229  *
 230  * Returns the requested job, or %NULL if it doesn't exist.
 231  */
 232 BlockJob *block_job_get(const char *id);
 233
 234 /**
 235  * block_job_create:
 236  * @job_id: The id of the newly-created job, or %NULL to have one
 237  * generated automatically.
 238  * @job_type: The class object for the newly-created job.
 239  * @bs: The block
 240  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 241  * @cb: Completion function for the job.
 242  * @opaque: Opaque pointer value passed to @cb.
 243  * @errp: Error object.
 244  *
 245  * Create a new long-running block device job and return it.  The job
 246  * will call @cb asynchronously when the job completes.  Note that
 247  * @bs may have been closed at the time the @cb it is called.  If
 248  * this is the case, the job may be reported as either cancelled or
 249  * completed.
 250  *
 251  * This function is not part of the public job interface; it should be
 252  * called from a wrapper that is specific to the job type.
 253  */
 254 void *block_job_create(const char *job_id, const BlockJobDriver *driver,
 255                        BlockDriverState *bs, int64_t speed,
 256                        BlockCompletionFunc *cb, void *opaque, Error **errp);
 257
 258 /**
 259  * block_job_add_bdrv:
 260  * @job: A block job
 261  * @bs: A BlockDriverState that is involved in @job
 262  *
 263  * Add @bs to the list of BlockDriverState that are involved in
 264  * @job. This means that all operations will be blocked on @bs while
 265  * @job exists.
 266  */
 267 void block_job_add_bdrv(BlockJob *job, BlockDriverState *bs);
 268
 269 /**
 270  * block_job_sleep_ns:
 271  * @job: The job that calls the function.
 272  * @clock: The clock to sleep on.
 273  * @ns: How many nanoseconds to stop for.
 274  *
 275  * Put the job to sleep (assuming that it wasn't canceled) for @ns
 276  * nanoseconds.  Canceling the job will interrupt the wait immediately.
 277  */
 278 void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns);
 279
 280 /**
 281  * block_job_yield:
 282  * @job: The job that calls the function.
 283  *
 284  * Yield the block job coroutine.
 285  */
 286 void block_job_yield(BlockJob *job);
 287
 288 /**
 289  * block_job_ref:
 290  * @bs: The block device.
 291  *
 292  * Grab a reference to the block job. Should be paired with block_job_unref.
 293  */
 294 void block_job_ref(BlockJob *job);
 295
 296 /**
 297  * block_job_unref:
 298  * @bs: The block device.
 299  *
 300  * Release reference to the block job and release resources if it is the last
 301  * reference.
 302  */
 303 void block_job_unref(BlockJob *job);
 304
 305 /**
 306  * block_job_completed:
 307  * @job: The job being completed.
 308  * @ret: The status code.
 309  *
 310  * Call the completion function that was registered at creation time, and
 311  * free @job.
 312  */
 313 void block_job_completed(BlockJob *job, int ret);
 314
 315 /**
 316  * block_job_set_speed:
 317  * @job: The job to set the speed for.
 318  * @speed: The new value
 319  * @errp: Error object.
 320  *
 321  * Set a rate-limiting parameter for the job; the actual meaning may
 322  * vary depending on the job type.
 323  */
 324 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
 325
 326 /**
 327  * block_job_cancel:
 328  * @job: The job to be canceled.
 329  *
 330  * Asynchronously cancel the specified job.
 331  */
 332 void block_job_cancel(BlockJob *job);
 333
 334 /**
 335  * block_job_complete:
 336  * @job: The job to be completed.
 337  * @errp: Error object.
 338  *
 339  * Asynchronously complete the specified job.
 340  */
 341 void block_job_complete(BlockJob *job, Error **errp);
 342
 343 /**
 344  * block_job_is_cancelled:
 345  * @job: The job being queried.
 346  *
 347  * Returns whether the job is scheduled for cancellation.
 348  */
 349 bool block_job_is_cancelled(BlockJob *job);
 350
 351 /**
 352  * block_job_query:
 353  * @job: The job to get information about.
 354  *
 355  * Return information about a job.
 356  */
 357 BlockJobInfo *block_job_query(BlockJob *job);
 358
 359 /**
 360  * block_job_pause_point:
 361  * @job: The job that is ready to pause.
 362  *
 363  * Pause now if block_job_pause() has been called.  Block jobs that perform
 364  * lots of I/O must call this between requests so that the job can be paused.
 365  */
 366 void coroutine_fn block_job_pause_point(BlockJob *job);
 367
 368 /**
 369  * block_job_pause:
 370  * @job: The job to be paused.
 371  *
 372  * Asynchronously pause the specified job.
 373  */
 374 void block_job_pause(BlockJob *job);
 375
 376 /**
 377  * block_job_resume:
 378  * @job: The job to be resumed.
 379  *
 380  * Resume the specified job.  Must be paired with a preceding block_job_pause.
 381  */
 382 void block_job_resume(BlockJob *job);
 383
 384 /**
 385  * block_job_enter:
 386  * @job: The job to enter.
 387  *
 388  * Continue the specified job by entering the coroutine.
 389  */
 390 void block_job_enter(BlockJob *job);
 391
 392 /**
 393  * block_job_event_cancelled:
 394  * @job: The job whose information is requested.
 395  *
 396  * Send a BLOCK_JOB_CANCELLED event for the specified job.
 397  */
 398 void block_job_event_cancelled(BlockJob *job);
 399
 400 /**
 401  * block_job_ready:
 402  * @job: The job which is now ready to complete.
 403  * @msg: Error message. Only present on failure.
 404  *
 405  * Send a BLOCK_JOB_COMPLETED event for the specified job.
 406  */
 407 void block_job_event_completed(BlockJob *job, const char *msg);
 408
 409 /**
 410  * block_job_ready:
 411  * @job: The job which is now ready to complete.
 412  *
 413  * Send a BLOCK_JOB_READY event for the specified job.
 414  */
 415 void block_job_event_ready(BlockJob *job);
 416
 417 /**
 418  * block_job_cancel_sync:
 419  * @job: The job to be canceled.
 420  *
 421  * Synchronously cancel the job.  The completion callback is called
 422  * before the function returns.  The job may actually complete
 423  * instead of canceling itself; the circumstances under which this
 424  * happens depend on the kind of job that is active.
 425  *
 426  * Returns the return value from the job if the job actually completed
 427  * during the call, or -ECANCELED if it was canceled.
 428  */
 429 int block_job_cancel_sync(BlockJob *job);
 430
 431 /**
 432  * block_job_cancel_sync_all:
 433  *
 434  * Synchronously cancels all jobs using block_job_cancel_sync().
 435  */
 436 void block_job_cancel_sync_all(void);
 437
 438 /**
 439  * block_job_complete_sync:
 440  * @job: The job to be completed.
 441  * @errp: Error object which may be set by block_job_complete(); this is not
 442  *        necessarily set on every error, the job return value has to be
 443  *        checked as well.
 444  *
 445  * Synchronously complete the job.  The completion callback is called before the
 446  * function returns, unless it is NULL (which is permissible when using this
 447  * function).
 448  *
 449  * Returns the return value from the job.
 450  */
 451 int block_job_complete_sync(BlockJob *job, Error **errp);
 452
 453 /**
 454  * block_job_iostatus_reset:
 455  * @job: The job whose I/O status should be reset.
 456  *
 457  * Reset I/O status on @job and on BlockDriverState objects it uses,
 458  * other than job->blk.
 459  */
 460 void block_job_iostatus_reset(BlockJob *job);
 461
 462 /**
 463  * block_job_error_action:
 464  * @job: The job to signal an error for.
 465  * @on_err: The error action setting.
 466  * @is_read: Whether the operation was a read.
 467  * @error: The error that was reported.
 468  *
 469  * Report an I/O error for a block job and possibly stop the VM.  Return the
 470  * action that was selected based on @on_err and @error.
 471  */
 472 BlockErrorAction block_job_error_action(BlockJob *job, BlockdevOnError on_err,
 473                                         int is_read, int error);
 474
 475 typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque);
 476
 477 /**
 478  * block_job_defer_to_main_loop:
 479  * @job: The job
 480  * @fn: The function to run in the main loop
 481  * @opaque: The opaque value that is passed to @fn
 482  *
 483  * Execute a given function in the main loop with the BlockDriverState
 484  * AioContext acquired.  Block jobs must call bdrv_unref(), bdrv_close(), and
 485  * anything that uses bdrv_drain_all() in the main loop.
 486  *
 487  * The @job AioContext is held while @fn executes.
 488  */
 489 void block_job_defer_to_main_loop(BlockJob *job,
 490                                   BlockJobDeferToMainLoopFn *fn,
 491                                   void *opaque);
 492
 493 /**
 494  * block_job_txn_new:
 495  *
 496  * Allocate and return a new block job transaction.  Jobs can be added to the
 497  * transaction using block_job_txn_add_job().
 498  *
 499  * The transaction is automatically freed when the last job completes or is
 500  * cancelled.
 501  *
 502  * All jobs in the transaction either complete successfully or fail/cancel as a
 503  * group.  Jobs wait for each other before completing.  Cancelling one job
 504  * cancels all jobs in the transaction.
 505  */
 506 BlockJobTxn *block_job_txn_new(void);
 507
 508 /**
 509  * block_job_txn_unref:
 510  *
 511  * Release a reference that was previously acquired with block_job_txn_add_job
 512  * or block_job_txn_new. If it's the last reference to the object, it will be
 513  * freed.
 514  */
 515 void block_job_txn_unref(BlockJobTxn *txn);
 516
 517 /**
 518  * block_job_txn_add_job:
 519  * @txn: The transaction (may be NULL)
 520  * @job: Job to add to the transaction
 521  *
 522  * Add @job to the transaction.  The @job must not already be in a transaction.
 523  * The caller must call either block_job_txn_unref() or block_job_completed()
 524  * to release the reference that is automatically grabbed here.
 525  */
 526 void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job);
 527
 528 #endif