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_id: The id of the newly-created job, or %NULL to have one
 227  * generated automatically.
 228  * @job_type: The class object for the newly-created job.
 229  * @bs: The block
 230  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 231  * @cb: Completion function for the job.
 232  * @opaque: Opaque pointer value passed to @cb.
 233  * @errp: Error object.
 234  *
 235  * Create a new long-running block device job and return it.  The job
 236  * will call @cb asynchronously when the job completes.  Note that
 237  * @bs may have been closed at the time the @cb it is called.  If
 238  * this is the case, the job may be reported as either cancelled or
 239  * completed.
 240  *
 241  * This function is not part of the public job interface; it should be
 242  * called from a wrapper that is specific to the job type.
 243  */
 244 void *block_job_create(const char *job_id, const BlockJobDriver *driver,
 245                        BlockDriverState *bs, int64_t speed,
 246                        BlockCompletionFunc *cb, void *opaque, Error **errp);
 247
 248 /**
 249  * block_job_sleep_ns:
 250  * @job: The job that calls the function.
 251  * @clock: The clock to sleep on.
 252  * @ns: How many nanoseconds to stop for.
 253  *
 254  * Put the job to sleep (assuming that it wasn't canceled) for @ns
 255  * nanoseconds.  Canceling the job will interrupt the wait immediately.
 256  */
 257 void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns);
 258
 259 /**
 260  * block_job_yield:
 261  * @job: The job that calls the function.
 262  *
 263  * Yield the block job coroutine.
 264  */
 265 void block_job_yield(BlockJob *job);
 266
 267 /**
 268  * block_job_ref:
 269  * @bs: The block device.
 270  *
 271  * Grab a reference to the block job. Should be paired with block_job_unref.
 272  */
 273 void block_job_ref(BlockJob *job);
 274
 275 /**
 276  * block_job_unref:
 277  * @bs: The block device.
 278  *
 279  * Release reference to the block job and release resources if it is the last
 280  * reference.
 281  */
 282 void block_job_unref(BlockJob *job);
 283
 284 /**
 285  * block_job_completed:
 286  * @job: The job being completed.
 287  * @ret: The status code.
 288  *
 289  * Call the completion function that was registered at creation time, and
 290  * free @job.
 291  */
 292 void block_job_completed(BlockJob *job, int ret);
 293
 294 /**
 295  * block_job_set_speed:
 296  * @job: The job to set the speed for.
 297  * @speed: The new value
 298  * @errp: Error object.
 299  *
 300  * Set a rate-limiting parameter for the job; the actual meaning may
 301  * vary depending on the job type.
 302  */
 303 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
 304
 305 /**
 306  * block_job_cancel:
 307  * @job: The job to be canceled.
 308  *
 309  * Asynchronously cancel the specified job.
 310  */
 311 void block_job_cancel(BlockJob *job);
 312
 313 /**
 314  * block_job_complete:
 315  * @job: The job to be completed.
 316  * @errp: Error object.
 317  *
 318  * Asynchronously complete the specified job.
 319  */
 320 void block_job_complete(BlockJob *job, Error **errp);
 321
 322 /**
 323  * block_job_is_cancelled:
 324  * @job: The job being queried.
 325  *
 326  * Returns whether the job is scheduled for cancellation.
 327  */
 328 bool block_job_is_cancelled(BlockJob *job);
 329
 330 /**
 331  * block_job_query:
 332  * @job: The job to get information about.
 333  *
 334  * Return information about a job.
 335  */
 336 BlockJobInfo *block_job_query(BlockJob *job);
 337
 338 /**
 339  * block_job_pause_point:
 340  * @job: The job that is ready to pause.
 341  *
 342  * Pause now if block_job_pause() has been called.  Block jobs that perform
 343  * lots of I/O must call this between requests so that the job can be paused.
 344  */
 345 void coroutine_fn block_job_pause_point(BlockJob *job);
 346
 347 /**
 348  * block_job_pause:
 349  * @job: The job to be paused.
 350  *
 351  * Asynchronously pause the specified job.
 352  */
 353 void block_job_pause(BlockJob *job);
 354
 355 /**
 356  * block_job_resume:
 357  * @job: The job to be resumed.
 358  *
 359  * Resume the specified job.  Must be paired with a preceding block_job_pause.
 360  */
 361 void block_job_resume(BlockJob *job);
 362
 363 /**
 364  * block_job_enter:
 365  * @job: The job to enter.
 366  *
 367  * Continue the specified job by entering the coroutine.
 368  */
 369 void block_job_enter(BlockJob *job);
 370
 371 /**
 372  * block_job_event_cancelled:
 373  * @job: The job whose information is requested.
 374  *
 375  * Send a BLOCK_JOB_CANCELLED event for the specified job.
 376  */
 377 void block_job_event_cancelled(BlockJob *job);
 378
 379 /**
 380  * block_job_ready:
 381  * @job: The job which is now ready to complete.
 382  * @msg: Error message. Only present on failure.
 383  *
 384  * Send a BLOCK_JOB_COMPLETED event for the specified job.
 385  */
 386 void block_job_event_completed(BlockJob *job, const char *msg);
 387
 388 /**
 389  * block_job_ready:
 390  * @job: The job which is now ready to complete.
 391  *
 392  * Send a BLOCK_JOB_READY event for the specified job.
 393  */
 394 void block_job_event_ready(BlockJob *job);
 395
 396 /**
 397  * block_job_cancel_sync:
 398  * @job: The job to be canceled.
 399  *
 400  * Synchronously cancel the job.  The completion callback is called
 401  * before the function returns.  The job may actually complete
 402  * instead of canceling itself; the circumstances under which this
 403  * happens depend on the kind of job that is active.
 404  *
 405  * Returns the return value from the job if the job actually completed
 406  * during the call, or -ECANCELED if it was canceled.
 407  */
 408 int block_job_cancel_sync(BlockJob *job);
 409
 410 /**
 411  * block_job_cancel_sync_all:
 412  *
 413  * Synchronously cancels all jobs using block_job_cancel_sync().
 414  */
 415 void block_job_cancel_sync_all(void);
 416
 417 /**
 418  * block_job_complete_sync:
 419  * @job: The job to be completed.
 420  * @errp: Error object which may be set by block_job_complete(); this is not
 421  *        necessarily set on every error, the job return value has to be
 422  *        checked as well.
 423  *
 424  * Synchronously complete the job.  The completion callback is called before the
 425  * function returns, unless it is NULL (which is permissible when using this
 426  * function).
 427  *
 428  * Returns the return value from the job.
 429  */
 430 int block_job_complete_sync(BlockJob *job, Error **errp);
 431
 432 /**
 433  * block_job_iostatus_reset:
 434  * @job: The job whose I/O status should be reset.
 435  *
 436  * Reset I/O status on @job and on BlockDriverState objects it uses,
 437  * other than job->blk.
 438  */
 439 void block_job_iostatus_reset(BlockJob *job);
 440
 441 /**
 442  * block_job_error_action:
 443  * @job: The job to signal an error for.
 444  * @on_err: The error action setting.
 445  * @is_read: Whether the operation was a read.
 446  * @error: The error that was reported.
 447  *
 448  * Report an I/O error for a block job and possibly stop the VM.  Return the
 449  * action that was selected based on @on_err and @error.
 450  */
 451 BlockErrorAction block_job_error_action(BlockJob *job, BlockdevOnError on_err,
 452                                         int is_read, int error);
 453
 454 typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque);
 455
 456 /**
 457  * block_job_defer_to_main_loop:
 458  * @job: The job
 459  * @fn: The function to run in the main loop
 460  * @opaque: The opaque value that is passed to @fn
 461  *
 462  * Execute a given function in the main loop with the BlockDriverState
 463  * AioContext acquired.  Block jobs must call bdrv_unref(), bdrv_close(), and
 464  * anything that uses bdrv_drain_all() in the main loop.
 465  *
 466  * The @job AioContext is held while @fn executes.
 467  */
 468 void block_job_defer_to_main_loop(BlockJob *job,
 469                                   BlockJobDeferToMainLoopFn *fn,
 470                                   void *opaque);
 471
 472 /**
 473  * block_job_txn_new:
 474  *
 475  * Allocate and return a new block job transaction.  Jobs can be added to the
 476  * transaction using block_job_txn_add_job().
 477  *
 478  * The transaction is automatically freed when the last job completes or is
 479  * cancelled.
 480  *
 481  * All jobs in the transaction either complete successfully or fail/cancel as a
 482  * group.  Jobs wait for each other before completing.  Cancelling one job
 483  * cancels all jobs in the transaction.
 484  */
 485 BlockJobTxn *block_job_txn_new(void);
 486
 487 /**
 488  * block_job_txn_unref:
 489  *
 490  * Release a reference that was previously acquired with block_job_txn_add_job
 491  * or block_job_txn_new. If it's the last reference to the object, it will be
 492  * freed.
 493  */
 494 void block_job_txn_unref(BlockJobTxn *txn);
 495
 496 /**
 497  * block_job_txn_add_job:
 498  * @txn: The transaction (may be NULL)
 499  * @job: Job to add to the transaction
 500  *
 501  * Add @job to the transaction.  The @job must not already be in a transaction.
 502  * The caller must call either block_job_txn_unref() or block_job_completed()
 503  * to release the reference that is automatically grabbed here.
 504  */
 505 void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job);
 506
 507 #endif