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 } BlockJobDriver;
  74
  75 /**
  76  * BlockJob:
  77  *
  78  * Long-running operation on a BlockDriverState.
  79  */
  80 struct BlockJob {
  81     /** The job type, including the job vtable.  */
  82     const BlockJobDriver *driver;
  83
  84     /** The block device on which the job is operating.  */
  85     BlockBackend *blk;
  86
  87     /**
  88      * The ID of the block job. Currently the BlockBackend name of the BDS
  89      * owning the job at the time when the job is started.
  90      *
  91      * TODO Decouple block job IDs from BlockBackend names
  92      */
  93     char *id;
  94
  95     /**
  96      * The coroutine that executes the job.  If not NULL, it is
  97      * reentered when busy is false and the job is cancelled.
  98      */
  99     Coroutine *co;
 100
 101     /**
 102      * Set to true if the job should cancel itself.  The flag must
 103      * always be tested just before toggling the busy flag from false
 104      * to true.  After a job has been cancelled, it should only yield
 105      * if #aio_poll will ("sooner or later") reenter the coroutine.
 106      */
 107     bool cancelled;
 108
 109     /**
 110      * Counter for pause request. If non-zero, the block job is either paused,
 111      * or if busy == true will pause itself as soon as possible.
 112      */
 113     int pause_count;
 114
 115     /**
 116      * Set to true if the job is paused by user.  Can be unpaused with the
 117      * block-job-resume QMP command.
 118      */
 119     bool user_paused;
 120
 121     /**
 122      * Set to false by the job while it is in a quiescent state, where
 123      * no I/O is pending and the job has yielded on any condition
 124      * that is not detected by #aio_poll, such as a timer.
 125      */
 126     bool busy;
 127
 128     /**
 129      * Set to true when the job is ready to be completed.
 130      */
 131     bool ready;
 132
 133     /**
 134      * Set to true when the job has deferred work to the main loop.
 135      */
 136     bool deferred_to_main_loop;
 137
 138     /** Element of the list of block jobs */
 139     QLIST_ENTRY(BlockJob) job_list;
 140
 141     /** Status that is published by the query-block-jobs QMP API */
 142     BlockDeviceIoStatus iostatus;
 143
 144     /** Offset that is published by the query-block-jobs QMP API */
 145     int64_t offset;
 146
 147     /** Length that is published by the query-block-jobs QMP API */
 148     int64_t len;
 149
 150     /** Speed that was set with @block_job_set_speed.  */
 151     int64_t speed;
 152
 153     /** The completion function that will be called when the job completes.  */
 154     BlockCompletionFunc *cb;
 155
 156     /** Block other operations when block job is running */
 157     Error *blocker;
 158
 159     /** The opaque value that is passed to the completion function.  */
 160     void *opaque;
 161
 162     /** Reference count of the block job */
 163     int refcnt;
 164
 165     /* True if this job has reported completion by calling block_job_completed.
 166      */
 167     bool completed;
 168
 169     /* ret code passed to block_job_completed.
 170      */
 171     int ret;
 172
 173     /** Non-NULL if this job is part of a transaction */
 174     BlockJobTxn *txn;
 175     QLIST_ENTRY(BlockJob) txn_list;
 176 };
 177
 178 /**
 179  * block_job_next:
 180  * @job: A block job, or %NULL.
 181  *
 182  * Get the next element from the list of block jobs after @job, or the
 183  * first one if @job is %NULL.
 184  *
 185  * Returns the requested job, or %NULL if there are no more jobs left.
 186  */
 187 BlockJob *block_job_next(BlockJob *job);
 188
 189 /**
 190  * block_job_create:
 191  * @job_type: The class object for the newly-created job.
 192  * @bs: The block
 193  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 194  * @cb: Completion function for the job.
 195  * @opaque: Opaque pointer value passed to @cb.
 196  * @errp: Error object.
 197  *
 198  * Create a new long-running block device job and return it.  The job
 199  * will call @cb asynchronously when the job completes.  Note that
 200  * @bs may have been closed at the time the @cb it is called.  If
 201  * this is the case, the job may be reported as either cancelled or
 202  * completed.
 203  *
 204  * This function is not part of the public job interface; it should be
 205  * called from a wrapper that is specific to the job type.
 206  */
 207 void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
 208                        int64_t speed, BlockCompletionFunc *cb,
 209                        void *opaque, Error **errp);
 210
 211 /**
 212  * block_job_sleep_ns:
 213  * @job: The job that calls the function.
 214  * @clock: The clock to sleep on.
 215  * @ns: How many nanoseconds to stop for.
 216  *
 217  * Put the job to sleep (assuming that it wasn't canceled) for @ns
 218  * nanoseconds.  Canceling the job will interrupt the wait immediately.
 219  */
 220 void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns);
 221
 222 /**
 223  * block_job_yield:
 224  * @job: The job that calls the function.
 225  *
 226  * Yield the block job coroutine.
 227  */
 228 void block_job_yield(BlockJob *job);
 229
 230 /**
 231  * block_job_ref:
 232  * @bs: The block device.
 233  *
 234  * Grab a reference to the block job. Should be paired with block_job_unref.
 235  */
 236 void block_job_ref(BlockJob *job);
 237
 238 /**
 239  * block_job_unref:
 240  * @bs: The block device.
 241  *
 242  * Release reference to the block job and release resources if it is the last
 243  * reference.
 244  */
 245 void block_job_unref(BlockJob *job);
 246
 247 /**
 248  * block_job_completed:
 249  * @job: The job being completed.
 250  * @ret: The status code.
 251  *
 252  * Call the completion function that was registered at creation time, and
 253  * free @job.
 254  */
 255 void block_job_completed(BlockJob *job, int ret);
 256
 257 /**
 258  * block_job_set_speed:
 259  * @job: The job to set the speed for.
 260  * @speed: The new value
 261  * @errp: Error object.
 262  *
 263  * Set a rate-limiting parameter for the job; the actual meaning may
 264  * vary depending on the job type.
 265  */
 266 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
 267
 268 /**
 269  * block_job_cancel:
 270  * @job: The job to be canceled.
 271  *
 272  * Asynchronously cancel the specified job.
 273  */
 274 void block_job_cancel(BlockJob *job);
 275
 276 /**
 277  * block_job_complete:
 278  * @job: The job to be completed.
 279  * @errp: Error object.
 280  *
 281  * Asynchronously complete the specified job.
 282  */
 283 void block_job_complete(BlockJob *job, Error **errp);
 284
 285 /**
 286  * block_job_is_cancelled:
 287  * @job: The job being queried.
 288  *
 289  * Returns whether the job is scheduled for cancellation.
 290  */
 291 bool block_job_is_cancelled(BlockJob *job);
 292
 293 /**
 294  * block_job_query:
 295  * @job: The job to get information about.
 296  *
 297  * Return information about a job.
 298  */
 299 BlockJobInfo *block_job_query(BlockJob *job);
 300
 301 /**
 302  * block_job_pause:
 303  * @job: The job to be paused.
 304  *
 305  * Asynchronously pause the specified job.
 306  */
 307 void block_job_pause(BlockJob *job);
 308
 309 /**
 310  * block_job_resume:
 311  * @job: The job to be resumed.
 312  *
 313  * Resume the specified job.  Must be paired with a preceding block_job_pause.
 314  */
 315 void block_job_resume(BlockJob *job);
 316
 317 /**
 318  * block_job_enter:
 319  * @job: The job to enter.
 320  *
 321  * Continue the specified job by entering the coroutine.
 322  */
 323 void block_job_enter(BlockJob *job);
 324
 325 /**
 326  * block_job_event_cancelled:
 327  * @job: The job whose information is requested.
 328  *
 329  * Send a BLOCK_JOB_CANCELLED event for the specified job.
 330  */
 331 void block_job_event_cancelled(BlockJob *job);
 332
 333 /**
 334  * block_job_ready:
 335  * @job: The job which is now ready to complete.
 336  * @msg: Error message. Only present on failure.
 337  *
 338  * Send a BLOCK_JOB_COMPLETED event for the specified job.
 339  */
 340 void block_job_event_completed(BlockJob *job, const char *msg);
 341
 342 /**
 343  * block_job_ready:
 344  * @job: The job which is now ready to complete.
 345  *
 346  * Send a BLOCK_JOB_READY event for the specified job.
 347  */
 348 void block_job_event_ready(BlockJob *job);
 349
 350 /**
 351  * block_job_is_paused:
 352  * @job: The job being queried.
 353  *
 354  * Returns whether the job is currently paused, or will pause
 355  * as soon as it reaches a sleeping point.
 356  */
 357 bool block_job_is_paused(BlockJob *job);
 358
 359 /**
 360  * block_job_cancel_sync:
 361  * @job: The job to be canceled.
 362  *
 363  * Synchronously cancel the job.  The completion callback is called
 364  * before the function returns.  The job may actually complete
 365  * instead of canceling itself; the circumstances under which this
 366  * happens depend on the kind of job that is active.
 367  *
 368  * Returns the return value from the job if the job actually completed
 369  * during the call, or -ECANCELED if it was canceled.
 370  */
 371 int block_job_cancel_sync(BlockJob *job);
 372
 373 /**
 374  * block_job_cancel_sync_all:
 375  *
 376  * Synchronously cancels all jobs using block_job_cancel_sync().
 377  */
 378 void block_job_cancel_sync_all(void);
 379
 380 /**
 381  * block_job_complete_sync:
 382  * @job: The job to be completed.
 383  * @errp: Error object which may be set by block_job_complete(); this is not
 384  *        necessarily set on every error, the job return value has to be
 385  *        checked as well.
 386  *
 387  * Synchronously complete the job.  The completion callback is called before the
 388  * function returns, unless it is NULL (which is permissible when using this
 389  * function).
 390  *
 391  * Returns the return value from the job.
 392  */
 393 int block_job_complete_sync(BlockJob *job, Error **errp);
 394
 395 /**
 396  * block_job_iostatus_reset:
 397  * @job: The job whose I/O status should be reset.
 398  *
 399  * Reset I/O status on @job and on BlockDriverState objects it uses,
 400  * other than job->blk.
 401  */
 402 void block_job_iostatus_reset(BlockJob *job);
 403
 404 /**
 405  * block_job_error_action:
 406  * @job: The job to signal an error for.
 407  * @on_err: The error action setting.
 408  * @is_read: Whether the operation was a read.
 409  * @error: The error that was reported.
 410  *
 411  * Report an I/O error for a block job and possibly stop the VM.  Return the
 412  * action that was selected based on @on_err and @error.
 413  */
 414 BlockErrorAction block_job_error_action(BlockJob *job, BlockdevOnError on_err,
 415                                         int is_read, int error);
 416
 417 typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque);
 418
 419 /**
 420  * block_job_defer_to_main_loop:
 421  * @job: The job
 422  * @fn: The function to run in the main loop
 423  * @opaque: The opaque value that is passed to @fn
 424  *
 425  * Execute a given function in the main loop with the BlockDriverState
 426  * AioContext acquired.  Block jobs must call bdrv_unref(), bdrv_close(), and
 427  * anything that uses bdrv_drain_all() in the main loop.
 428  *
 429  * The @job AioContext is held while @fn executes.
 430  */
 431 void block_job_defer_to_main_loop(BlockJob *job,
 432                                   BlockJobDeferToMainLoopFn *fn,
 433                                   void *opaque);
 434
 435 /**
 436  * block_job_txn_new:
 437  *
 438  * Allocate and return a new block job transaction.  Jobs can be added to the
 439  * transaction using block_job_txn_add_job().
 440  *
 441  * The transaction is automatically freed when the last job completes or is
 442  * cancelled.
 443  *
 444  * All jobs in the transaction either complete successfully or fail/cancel as a
 445  * group.  Jobs wait for each other before completing.  Cancelling one job
 446  * cancels all jobs in the transaction.
 447  */
 448 BlockJobTxn *block_job_txn_new(void);
 449
 450 /**
 451  * block_job_txn_unref:
 452  *
 453  * Release a reference that was previously acquired with block_job_txn_add_job
 454  * or block_job_txn_new. If it's the last reference to the object, it will be
 455  * freed.
 456  */
 457 void block_job_txn_unref(BlockJobTxn *txn);
 458
 459 /**
 460  * block_job_txn_add_job:
 461  * @txn: The transaction (may be NULL)
 462  * @job: Job to add to the transaction
 463  *
 464  * Add @job to the transaction.  The @job must not already be in a transaction.
 465  * The caller must call either block_job_txn_unref() or block_job_completed()
 466  * to release the reference that is automatically grabbed here.
 467  */
 468 void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job);
 469
 470 #endif