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 } BlockJobDriver;
  54
  55 /**
  56  * BlockJob:
  57  *
  58  * Long-running operation on a BlockDriverState.
  59  */
  60 struct BlockJob {
  61     /** The job type, including the job vtable.  */
  62     const BlockJobDriver *driver;
  63
  64     /** The block device on which the job is operating.  */
  65     BlockDriverState *bs;
  66
  67     /**
  68      * The coroutine that executes the job.  If not NULL, it is
  69      * reentered when busy is false and the job is cancelled.
  70      */
  71     Coroutine *co;
  72
  73     /**
  74      * Set to true if the job should cancel itself.  The flag must
  75      * always be tested just before toggling the busy flag from false
  76      * to true.  After a job has been cancelled, it should only yield
  77      * if #aio_poll will ("sooner or later") reenter the coroutine.
  78      */
  79     bool cancelled;
  80
  81     /**
  82      * Set to true if the job is either paused, or will pause itself
  83      * as soon as possible (if busy == true).
  84      */
  85     bool paused;
  86
  87     /**
  88      * Set to false by the job while it is in a quiescent state, where
  89      * no I/O is pending and the job has yielded on any condition
  90      * that is not detected by #aio_poll, such as a timer.
  91      */
  92     bool busy;
  93
  94     /**
  95      * Set to true when the job is ready to be completed.
  96      */
  97     bool ready;
  98
  99     /** Status that is published by the query-block-jobs QMP API */
 100     BlockDeviceIoStatus iostatus;
 101
 102     /** Offset that is published by the query-block-jobs QMP API */
 103     int64_t offset;
 104
 105     /** Length that is published by the query-block-jobs QMP API */
 106     int64_t len;
 107
 108     /** Speed that was set with @block_job_set_speed.  */
 109     int64_t speed;
 110
 111     /** The completion function that will be called when the job completes.  */
 112     BlockCompletionFunc *cb;
 113
 114     /** Block other operations when block job is running */
 115     Error *blocker;
 116
 117     /** The opaque value that is passed to the completion function.  */
 118     void *opaque;
 119 };
 120
 121 /**
 122  * block_job_create:
 123  * @job_type: The class object for the newly-created job.
 124  * @bs: The block
 125  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 126  * @cb: Completion function for the job.
 127  * @opaque: Opaque pointer value passed to @cb.
 128  * @errp: Error object.
 129  *
 130  * Create a new long-running block device job and return it.  The job
 131  * will call @cb asynchronously when the job completes.  Note that
 132  * @bs may have been closed at the time the @cb it is called.  If
 133  * this is the case, the job may be reported as either cancelled or
 134  * completed.
 135  *
 136  * This function is not part of the public job interface; it should be
 137  * called from a wrapper that is specific to the job type.
 138  */
 139 void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
 140                        int64_t speed, BlockCompletionFunc *cb,
 141                        void *opaque, Error **errp);
 142
 143 /**
 144  * block_job_sleep_ns:
 145  * @job: The job that calls the function.
 146  * @clock: The clock to sleep on.
 147  * @ns: How many nanoseconds to stop for.
 148  *
 149  * Put the job to sleep (assuming that it wasn't canceled) for @ns
 150  * nanoseconds.  Canceling the job will interrupt the wait immediately.
 151  */
 152 void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns);
 153
 154 /**
 155  * block_job_yield:
 156  * @job: The job that calls the function.
 157  *
 158  * Yield the block job coroutine.
 159  */
 160 void block_job_yield(BlockJob *job);
 161
 162 /**
 163  * block_job_completed:
 164  * @job: The job being completed.
 165  * @ret: The status code.
 166  *
 167  * Call the completion function that was registered at creation time, and
 168  * free @job.
 169  */
 170 void block_job_completed(BlockJob *job, int ret);
 171
 172 /**
 173  * block_job_set_speed:
 174  * @job: The job to set the speed for.
 175  * @speed: The new value
 176  * @errp: Error object.
 177  *
 178  * Set a rate-limiting parameter for the job; the actual meaning may
 179  * vary depending on the job type.
 180  */
 181 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp);
 182
 183 /**
 184  * block_job_cancel:
 185  * @job: The job to be canceled.
 186  *
 187  * Asynchronously cancel the specified job.
 188  */
 189 void block_job_cancel(BlockJob *job);
 190
 191 /**
 192  * block_job_complete:
 193  * @job: The job to be completed.
 194  * @errp: Error object.
 195  *
 196  * Asynchronously complete the specified job.
 197  */
 198 void block_job_complete(BlockJob *job, Error **errp);
 199
 200 /**
 201  * block_job_is_cancelled:
 202  * @job: The job being queried.
 203  *
 204  * Returns whether the job is scheduled for cancellation.
 205  */
 206 bool block_job_is_cancelled(BlockJob *job);
 207
 208 /**
 209  * block_job_query:
 210  * @job: The job to get information about.
 211  *
 212  * Return information about a job.
 213  */
 214 BlockJobInfo *block_job_query(BlockJob *job);
 215
 216 /**
 217  * block_job_pause:
 218  * @job: The job to be paused.
 219  *
 220  * Asynchronously pause the specified job.
 221  */
 222 void block_job_pause(BlockJob *job);
 223
 224 /**
 225  * block_job_resume:
 226  * @job: The job to be resumed.
 227  *
 228  * Resume the specified job.
 229  */
 230 void block_job_resume(BlockJob *job);
 231
 232 /**
 233  * block_job_event_cancelled:
 234  * @job: The job whose information is requested.
 235  *
 236  * Send a BLOCK_JOB_CANCELLED event for the specified job.
 237  */
 238 void block_job_event_cancelled(BlockJob *job);
 239
 240 /**
 241  * block_job_ready:
 242  * @job: The job which is now ready to complete.
 243  * @msg: Error message. Only present on failure.
 244  *
 245  * Send a BLOCK_JOB_COMPLETED event for the specified job.
 246  */
 247 void block_job_event_completed(BlockJob *job, const char *msg);
 248
 249 /**
 250  * block_job_ready:
 251  * @job: The job which is now ready to complete.
 252  *
 253  * Send a BLOCK_JOB_READY event for the specified job.
 254  */
 255 void block_job_event_ready(BlockJob *job);
 256
 257 /**
 258  * block_job_is_paused:
 259  * @job: The job being queried.
 260  *
 261  * Returns whether the job is currently paused, or will pause
 262  * as soon as it reaches a sleeping point.
 263  */
 264 bool block_job_is_paused(BlockJob *job);
 265
 266 /**
 267  * block_job_cancel_sync:
 268  * @job: The job to be canceled.
 269  *
 270  * Synchronously cancel the job.  The completion callback is called
 271  * before the function returns.  The job may actually complete
 272  * instead of canceling itself; the circumstances under which this
 273  * happens depend on the kind of job that is active.
 274  *
 275  * Returns the return value from the job if the job actually completed
 276  * during the call, or -ECANCELED if it was canceled.
 277  */
 278 int block_job_cancel_sync(BlockJob *job);
 279
 280 /**
 281  * block_job_complete_sync:
 282  * @job: The job to be completed.
 283  * @errp: Error object which may be set by block_job_complete(); this is not
 284  *        necessarily set on every error, the job return value has to be
 285  *        checked as well.
 286  *
 287  * Synchronously complete the job.  The completion callback is called before the
 288  * function returns, unless it is NULL (which is permissible when using this
 289  * function).
 290  *
 291  * Returns the return value from the job.
 292  */
 293 int block_job_complete_sync(BlockJob *job, Error **errp);
 294
 295 /**
 296  * block_job_iostatus_reset:
 297  * @job: The job whose I/O status should be reset.
 298  *
 299  * Reset I/O status on @job and on BlockDriverState objects it uses,
 300  * other than job->bs.
 301  */
 302 void block_job_iostatus_reset(BlockJob *job);
 303
 304 /**
 305  * block_job_error_action:
 306  * @job: The job to signal an error for.
 307  * @bs: The block device on which to set an I/O error.
 308  * @on_err: The error action setting.
 309  * @is_read: Whether the operation was a read.
 310  * @error: The error that was reported.
 311  *
 312  * Report an I/O error for a block job and possibly stop the VM.  Return the
 313  * action that was selected based on @on_err and @error.
 314  */
 315 BlockErrorAction block_job_error_action(BlockJob *job, BlockDriverState *bs,
 316                                         BlockdevOnError on_err,
 317                                         int is_read, int error);
 318
 319 typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque);
 320
 321 /**
 322  * block_job_defer_to_main_loop:
 323  * @job: The job
 324  * @fn: The function to run in the main loop
 325  * @opaque: The opaque value that is passed to @fn
 326  *
 327  * Execute a given function in the main loop with the BlockDriverState
 328  * AioContext acquired.  Block jobs must call bdrv_unref(), bdrv_close(), and
 329  * anything that uses bdrv_drain_all() in the main loop.
 330  *
 331  * The @job AioContext is held while @fn executes.
 332  */
 333 void block_job_defer_to_main_loop(BlockJob *job,
 334                                   BlockJobDeferToMainLoopFn *fn,
 335                                   void *opaque);
 336
 337 #endif