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