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     BlockDriverState *bs;
  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     /** Status that is published by the query-block-jobs QMP API */
 134     BlockDeviceIoStatus iostatus;
 135
 136     /** Offset that is published by the query-block-jobs QMP API */
 137     int64_t offset;
 138
 139     /** Length that is published by the query-block-jobs QMP API */
 140     int64_t len;
 141
 142     /** Speed that was set with @block_job_set_speed.  */
 143     int64_t speed;
 144
 145     /** The completion function that will be called when the job completes.  */
 146     BlockCompletionFunc *cb;
 147
 148     /** Block other operations when block job is running */
 149     Error *blocker;
 150
 151     /** The opaque value that is passed to the completion function.  */
 152     void *opaque;
 153
 154     /** Reference count of the block job */
 155     int refcnt;
 156
 157     /* True if this job has reported completion by calling block_job_completed.
 158      */
 159     bool completed;
 160
 161     /* ret code passed to block_job_completed.
 162      */
 163     int ret;
 164
 165     /** Non-NULL if this job is part of a transaction */
 166     BlockJobTxn *txn;
 167     QLIST_ENTRY(BlockJob) txn_list;
 168 };
 169
 170 /**
 171  * block_job_create:
 172  * @job_type: The class object for the newly-created job.
 173  * @bs: The block
 174  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 175  * @cb: Completion function for the job.
 176  * @opaque: Opaque pointer value passed to @cb.
 177  * @errp: Error object.
 178  *
 179  * Create a new long-running block device job and return it.  The job
 180  * will call @cb asynchronously when the job completes.  Note that
 181  * @bs may have been closed at the time the @cb it is called.  If
 182  * this is the case, the job may be reported as either cancelled or
 183  * completed.
 184  *
 185  * This function is not part of the public job interface; it should be
 186  * called from a wrapper that is specific to the job type.
 187  */
 188 void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
 189                        int64_t speed, BlockCompletionFunc *cb,
 190                        void *opaque, Error **errp);
 191
 192 /**
 193  * block_job_sleep_ns:
 194  * @job: The job that calls the function.
 195  * @clock: The clock to sleep on.
 196  * @ns: How many nanoseconds to stop for.
 197  *
 198  * Put the job to sleep (assuming that it wasn't canceled) for @ns
 199  * nanoseconds.  Canceling the job will interrupt the wait immediately.
 200  */
 201 void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns);
 202
 203 /**
 204  * block_job_yield:
 205  * @job: The job that calls the function.
 206  *
 207  * Yield the block job coroutine.
 208  */
 209 void block_job_yield(BlockJob *job);
 210
 211 /**
 212  * block_job_ref:
 213  * @bs: The block device.
 214  *
 215  * Grab a reference to the block job. Should be paired with block_job_unref.
 216  */
 217 void block_job_ref(BlockJob *job);
 218
 219 /**
 220  * block_job_unref:
 221  * @bs: The block device.
 222  *
 223  * Release reference to the block job and release resources if it is the last
 224  * reference.
 225  */
 226 void block_job_unref(BlockJob *job);
 227
 228 /**
 229  * block_job_completed:
 230  * @job: The job being completed.
 231  * @ret: The status code.
 232  *
 233  * Call the completion function that was registered at creation time, and
 234  * free @job.
 235  */
 236 void block_job_completed(BlockJob *job, int ret);
 237
 238 /**
 239  * block_job_set_speed:
 240  * @job: The job to set the speed for.
 241  * @speed: The new value
 242  * @errp: Error object.
 243  *
 244  * Set a rate-limiting parameter for the job; the actual meaning may
 245  * vary depending on the job type.
 246  */
 247 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
 248
 249 /**
 250  * block_job_cancel:
 251  * @job: The job to be canceled.
 252  *
 253  * Asynchronously cancel the specified job.
 254  */
 255 void block_job_cancel(BlockJob *job);
 256
 257 /**
 258  * block_job_complete:
 259  * @job: The job to be completed.
 260  * @errp: Error object.
 261  *
 262  * Asynchronously complete the specified job.
 263  */
 264 void block_job_complete(BlockJob *job, Error **errp);
 265
 266 /**
 267  * block_job_is_cancelled:
 268  * @job: The job being queried.
 269  *
 270  * Returns whether the job is scheduled for cancellation.
 271  */
 272 bool block_job_is_cancelled(BlockJob *job);
 273
 274 /**
 275  * block_job_query:
 276  * @job: The job to get information about.
 277  *
 278  * Return information about a job.
 279  */
 280 BlockJobInfo *block_job_query(BlockJob *job);
 281
 282 /**
 283  * block_job_pause:
 284  * @job: The job to be paused.
 285  *
 286  * Asynchronously pause the specified job.
 287  */
 288 void block_job_pause(BlockJob *job);
 289
 290 /**
 291  * block_job_resume:
 292  * @job: The job to be resumed.
 293  *
 294  * Resume the specified job.  Must be paired with a preceding block_job_pause.
 295  */
 296 void block_job_resume(BlockJob *job);
 297
 298 /**
 299  * block_job_enter:
 300  * @job: The job to enter.
 301  *
 302  * Continue the specified job by entering the coroutine.
 303  */
 304 void block_job_enter(BlockJob *job);
 305
 306 /**
 307  * block_job_event_cancelled:
 308  * @job: The job whose information is requested.
 309  *
 310  * Send a BLOCK_JOB_CANCELLED event for the specified job.
 311  */
 312 void block_job_event_cancelled(BlockJob *job);
 313
 314 /**
 315  * block_job_ready:
 316  * @job: The job which is now ready to complete.
 317  * @msg: Error message. Only present on failure.
 318  *
 319  * Send a BLOCK_JOB_COMPLETED event for the specified job.
 320  */
 321 void block_job_event_completed(BlockJob *job, const char *msg);
 322
 323 /**
 324  * block_job_ready:
 325  * @job: The job which is now ready to complete.
 326  *
 327  * Send a BLOCK_JOB_READY event for the specified job.
 328  */
 329 void block_job_event_ready(BlockJob *job);
 330
 331 /**
 332  * block_job_is_paused:
 333  * @job: The job being queried.
 334  *
 335  * Returns whether the job is currently paused, or will pause
 336  * as soon as it reaches a sleeping point.
 337  */
 338 bool block_job_is_paused(BlockJob *job);
 339
 340 /**
 341  * block_job_cancel_sync:
 342  * @job: The job to be canceled.
 343  *
 344  * Synchronously cancel the job.  The completion callback is called
 345  * before the function returns.  The job may actually complete
 346  * instead of canceling itself; the circumstances under which this
 347  * happens depend on the kind of job that is active.
 348  *
 349  * Returns the return value from the job if the job actually completed
 350  * during the call, or -ECANCELED if it was canceled.
 351  */
 352 int block_job_cancel_sync(BlockJob *job);
 353
 354 /**
 355  * block_job_complete_sync:
 356  * @job: The job to be completed.
 357  * @errp: Error object which may be set by block_job_complete(); this is not
 358  *        necessarily set on every error, the job return value has to be
 359  *        checked as well.
 360  *
 361  * Synchronously complete the job.  The completion callback is called before the
 362  * function returns, unless it is NULL (which is permissible when using this
 363  * function).
 364  *
 365  * Returns the return value from the job.
 366  */
 367 int block_job_complete_sync(BlockJob *job, Error **errp);
 368
 369 /**
 370  * block_job_iostatus_reset:
 371  * @job: The job whose I/O status should be reset.
 372  *
 373  * Reset I/O status on @job and on BlockDriverState objects it uses,
 374  * other than job->bs.
 375  */
 376 void block_job_iostatus_reset(BlockJob *job);
 377
 378 /**
 379  * block_job_error_action:
 380  * @job: The job to signal an error for.
 381  * @bs: The block device on which to set an I/O error.
 382  * @on_err: The error action setting.
 383  * @is_read: Whether the operation was a read.
 384  * @error: The error that was reported.
 385  *
 386  * Report an I/O error for a block job and possibly stop the VM.  Return the
 387  * action that was selected based on @on_err and @error.
 388  */
 389 BlockErrorAction block_job_error_action(BlockJob *job, BlockDriverState *bs,
 390                                         BlockdevOnError on_err,
 391                                         int is_read, int error);
 392
 393 typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque);
 394
 395 /**
 396  * block_job_defer_to_main_loop:
 397  * @job: The job
 398  * @fn: The function to run in the main loop
 399  * @opaque: The opaque value that is passed to @fn
 400  *
 401  * Execute a given function in the main loop with the BlockDriverState
 402  * AioContext acquired.  Block jobs must call bdrv_unref(), bdrv_close(), and
 403  * anything that uses bdrv_drain_all() in the main loop.
 404  *
 405  * The @job AioContext is held while @fn executes.
 406  */
 407 void block_job_defer_to_main_loop(BlockJob *job,
 408                                   BlockJobDeferToMainLoopFn *fn,
 409                                   void *opaque);
 410
 411 /**
 412  * block_job_txn_new:
 413  *
 414  * Allocate and return a new block job transaction.  Jobs can be added to the
 415  * transaction using block_job_txn_add_job().
 416  *
 417  * The transaction is automatically freed when the last job completes or is
 418  * cancelled.
 419  *
 420  * All jobs in the transaction either complete successfully or fail/cancel as a
 421  * group.  Jobs wait for each other before completing.  Cancelling one job
 422  * cancels all jobs in the transaction.
 423  */
 424 BlockJobTxn *block_job_txn_new(void);
 425
 426 /**
 427  * block_job_txn_unref:
 428  *
 429  * Release a reference that was previously acquired with block_job_txn_add_job
 430  * or block_job_txn_new. If it's the last reference to the object, it will be
 431  * freed.
 432  */
 433 void block_job_txn_unref(BlockJobTxn *txn);
 434
 435 /**
 436  * block_job_txn_add_job:
 437  * @txn: The transaction (may be NULL)
 438  * @job: Job to add to the transaction
 439  *
 440  * Add @job to the transaction.  The @job must not already be in a transaction.
 441  * The caller must call either block_job_txn_unref() or block_job_completed()
 442  * to release the reference that is automatically grabbed here.
 443  */
 444 void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job);
 445
 446 #endif