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