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     /** The opaque value that is passed to the completion function.  */
 192     void *opaque;
 193
 194     /** Reference count of the block job */
 195     int refcnt;
 196
 197     /* True if this job has reported completion by calling block_job_completed.
 198      */
 199     bool completed;
 200
 201     /* ret code passed to block_job_completed.
 202      */
 203     int ret;
 204
 205     /** Non-NULL if this job is part of a transaction */
 206     BlockJobTxn *txn;
 207     QLIST_ENTRY(BlockJob) txn_list;
 208 };
 209
 210 /**
 211  * block_job_next:
 212  * @job: A block job, or %NULL.
 213  *
 214  * Get the next element from the list of block jobs after @job, or the
 215  * first one if @job is %NULL.
 216  *
 217  * Returns the requested job, or %NULL if there are no more jobs left.
 218  */
 219 BlockJob *block_job_next(BlockJob *job);
 220
 221 /**
 222  * block_job_get:
 223  * @id: The id of the block job.
 224  *
 225  * Get the block job identified by @id (which must not be %NULL).
 226  *
 227  * Returns the requested job, or %NULL if it doesn't exist.
 228  */
 229 BlockJob *block_job_get(const char *id);
 230
 231 /**
 232  * block_job_create:
 233  * @job_id: The id of the newly-created job, or %NULL to have one
 234  * generated automatically.
 235  * @job_type: The class object for the newly-created job.
 236  * @bs: The block
 237  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 238  * @cb: Completion function for the job.
 239  * @opaque: Opaque pointer value passed to @cb.
 240  * @errp: Error object.
 241  *
 242  * Create a new long-running block device job and return it.  The job
 243  * will call @cb asynchronously when the job completes.  Note that
 244  * @bs may have been closed at the time the @cb it is called.  If
 245  * this is the case, the job may be reported as either cancelled or
 246  * completed.
 247  *
 248  * This function is not part of the public job interface; it should be
 249  * called from a wrapper that is specific to the job type.
 250  */
 251 void *block_job_create(const char *job_id, const BlockJobDriver *driver,
 252                        BlockDriverState *bs, int64_t speed,
 253                        BlockCompletionFunc *cb, void *opaque, Error **errp);
 254
 255 /**
 256  * block_job_sleep_ns:
 257  * @job: The job that calls the function.
 258  * @clock: The clock to sleep on.
 259  * @ns: How many nanoseconds to stop for.
 260  *
 261  * Put the job to sleep (assuming that it wasn't canceled) for @ns
 262  * nanoseconds.  Canceling the job will interrupt the wait immediately.
 263  */
 264 void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns);
 265
 266 /**
 267  * block_job_yield:
 268  * @job: The job that calls the function.
 269  *
 270  * Yield the block job coroutine.
 271  */
 272 void block_job_yield(BlockJob *job);
 273
 274 /**
 275  * block_job_ref:
 276  * @bs: The block device.
 277  *
 278  * Grab a reference to the block job. Should be paired with block_job_unref.
 279  */
 280 void block_job_ref(BlockJob *job);
 281
 282 /**
 283  * block_job_unref:
 284  * @bs: The block device.
 285  *
 286  * Release reference to the block job and release resources if it is the last
 287  * reference.
 288  */
 289 void block_job_unref(BlockJob *job);
 290
 291 /**
 292  * block_job_completed:
 293  * @job: The job being completed.
 294  * @ret: The status code.
 295  *
 296  * Call the completion function that was registered at creation time, and
 297  * free @job.
 298  */
 299 void block_job_completed(BlockJob *job, int ret);
 300
 301 /**
 302  * block_job_set_speed:
 303  * @job: The job to set the speed for.
 304  * @speed: The new value
 305  * @errp: Error object.
 306  *
 307  * Set a rate-limiting parameter for the job; the actual meaning may
 308  * vary depending on the job type.
 309  */
 310 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
 311
 312 /**
 313  * block_job_cancel:
 314  * @job: The job to be canceled.
 315  *
 316  * Asynchronously cancel the specified job.
 317  */
 318 void block_job_cancel(BlockJob *job);
 319
 320 /**
 321  * block_job_complete:
 322  * @job: The job to be completed.
 323  * @errp: Error object.
 324  *
 325  * Asynchronously complete the specified job.
 326  */
 327 void block_job_complete(BlockJob *job, Error **errp);
 328
 329 /**
 330  * block_job_is_cancelled:
 331  * @job: The job being queried.
 332  *
 333  * Returns whether the job is scheduled for cancellation.
 334  */
 335 bool block_job_is_cancelled(BlockJob *job);
 336
 337 /**
 338  * block_job_query:
 339  * @job: The job to get information about.
 340  *
 341  * Return information about a job.
 342  */
 343 BlockJobInfo *block_job_query(BlockJob *job);
 344
 345 /**
 346  * block_job_pause_point:
 347  * @job: The job that is ready to pause.
 348  *
 349  * Pause now if block_job_pause() has been called.  Block jobs that perform
 350  * lots of I/O must call this between requests so that the job can be paused.
 351  */
 352 void coroutine_fn block_job_pause_point(BlockJob *job);
 353
 354 /**
 355  * block_job_pause:
 356  * @job: The job to be paused.
 357  *
 358  * Asynchronously pause the specified job.
 359  */
 360 void block_job_pause(BlockJob *job);
 361
 362 /**
 363  * block_job_resume:
 364  * @job: The job to be resumed.
 365  *
 366  * Resume the specified job.  Must be paired with a preceding block_job_pause.
 367  */
 368 void block_job_resume(BlockJob *job);
 369
 370 /**
 371  * block_job_enter:
 372  * @job: The job to enter.
 373  *
 374  * Continue the specified job by entering the coroutine.
 375  */
 376 void block_job_enter(BlockJob *job);
 377
 378 /**
 379  * block_job_event_cancelled:
 380  * @job: The job whose information is requested.
 381  *
 382  * Send a BLOCK_JOB_CANCELLED event for the specified job.
 383  */
 384 void block_job_event_cancelled(BlockJob *job);
 385
 386 /**
 387  * block_job_ready:
 388  * @job: The job which is now ready to complete.
 389  * @msg: Error message. Only present on failure.
 390  *
 391  * Send a BLOCK_JOB_COMPLETED event for the specified job.
 392  */
 393 void block_job_event_completed(BlockJob *job, const char *msg);
 394
 395 /**
 396  * block_job_ready:
 397  * @job: The job which is now ready to complete.
 398  *
 399  * Send a BLOCK_JOB_READY event for the specified job.
 400  */
 401 void block_job_event_ready(BlockJob *job);
 402
 403 /**
 404  * block_job_cancel_sync:
 405  * @job: The job to be canceled.
 406  *
 407  * Synchronously cancel the job.  The completion callback is called
 408  * before the function returns.  The job may actually complete
 409  * instead of canceling itself; the circumstances under which this
 410  * happens depend on the kind of job that is active.
 411  *
 412  * Returns the return value from the job if the job actually completed
 413  * during the call, or -ECANCELED if it was canceled.
 414  */
 415 int block_job_cancel_sync(BlockJob *job);
 416
 417 /**
 418  * block_job_cancel_sync_all:
 419  *
 420  * Synchronously cancels all jobs using block_job_cancel_sync().
 421  */
 422 void block_job_cancel_sync_all(void);
 423
 424 /**
 425  * block_job_complete_sync:
 426  * @job: The job to be completed.
 427  * @errp: Error object which may be set by block_job_complete(); this is not
 428  *        necessarily set on every error, the job return value has to be
 429  *        checked as well.
 430  *
 431  * Synchronously complete the job.  The completion callback is called before the
 432  * function returns, unless it is NULL (which is permissible when using this
 433  * function).
 434  *
 435  * Returns the return value from the job.
 436  */
 437 int block_job_complete_sync(BlockJob *job, Error **errp);
 438
 439 /**
 440  * block_job_iostatus_reset:
 441  * @job: The job whose I/O status should be reset.
 442  *
 443  * Reset I/O status on @job and on BlockDriverState objects it uses,
 444  * other than job->blk.
 445  */
 446 void block_job_iostatus_reset(BlockJob *job);
 447
 448 /**
 449  * block_job_error_action:
 450  * @job: The job to signal an error for.
 451  * @on_err: The error action setting.
 452  * @is_read: Whether the operation was a read.
 453  * @error: The error that was reported.
 454  *
 455  * Report an I/O error for a block job and possibly stop the VM.  Return the
 456  * action that was selected based on @on_err and @error.
 457  */
 458 BlockErrorAction block_job_error_action(BlockJob *job, BlockdevOnError on_err,
 459                                         int is_read, int error);
 460
 461 typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque);
 462
 463 /**
 464  * block_job_defer_to_main_loop:
 465  * @job: The job
 466  * @fn: The function to run in the main loop
 467  * @opaque: The opaque value that is passed to @fn
 468  *
 469  * Execute a given function in the main loop with the BlockDriverState
 470  * AioContext acquired.  Block jobs must call bdrv_unref(), bdrv_close(), and
 471  * anything that uses bdrv_drain_all() in the main loop.
 472  *
 473  * The @job AioContext is held while @fn executes.
 474  */
 475 void block_job_defer_to_main_loop(BlockJob *job,
 476                                   BlockJobDeferToMainLoopFn *fn,
 477                                   void *opaque);
 478
 479 /**
 480  * block_job_txn_new:
 481  *
 482  * Allocate and return a new block job transaction.  Jobs can be added to the
 483  * transaction using block_job_txn_add_job().
 484  *
 485  * The transaction is automatically freed when the last job completes or is
 486  * cancelled.
 487  *
 488  * All jobs in the transaction either complete successfully or fail/cancel as a
 489  * group.  Jobs wait for each other before completing.  Cancelling one job
 490  * cancels all jobs in the transaction.
 491  */
 492 BlockJobTxn *block_job_txn_new(void);
 493
 494 /**
 495  * block_job_txn_unref:
 496  *
 497  * Release a reference that was previously acquired with block_job_txn_add_job
 498  * or block_job_txn_new. If it's the last reference to the object, it will be
 499  * freed.
 500  */
 501 void block_job_txn_unref(BlockJobTxn *txn);
 502
 503 /**
 504  * block_job_txn_add_job:
 505  * @txn: The transaction (may be NULL)
 506  * @job: Job to add to the transaction
 507  *
 508  * Add @job to the transaction.  The @job must not already be in a transaction.
 509  * The caller must call either block_job_txn_unref() or block_job_completed()
 510  * to release the reference that is automatically grabbed here.
 511  */
 512 void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job);
 513
 514 #endif