| @@ -10,103 +10,239 @@ struct blk_mq_tags; · 9 unmodified lines |
| 10 | 10 | struct blk_flush_queue; |
| 11 | 11 | |
| 12 | 12 | /** |
| 13 | | − * struct blk_mq_hw_ctx - State for a hardware queue facing the hardware block device |
| 13 | + * struct blk_mq_hw_ctx - State for a hardware queue facing the hardware |
| 14 | + * block device |
| 14 | 15 | */ |
| 15 | 16 | struct blk_mq_hw_ctx { |
| 16 | 17 | struct { |
| 18 | + /** @lock: Protects the dispatch list. */ |
| 17 | 19 | spinlock_t lock; |
| 20 | + /** |
| 21 | + * @dispatch: Used for requests that are ready to be |
| 22 | + * dispatched to the hardware but for some reason (e.g. lack of |
| 23 | + * resources) could not be sent to the hardware. As soon as the |
| 24 | + * driver can send new requests, requests at this list will |
| 25 | + * be sent first for a fairer dispatch. |
| 26 | + */ |
| 18 | 27 | struct list_head dispatch; |
| 19 | | − unsigned long state; /* BLK_MQ_S_* flags */ |
| 28 | + /** |
| 29 | + * @state: BLK_MQ_S_* flags. Defines the state of the hw |
| 30 | + * queue (active, scheduled to restart, stopped). |
| 31 | + */ |
| 32 | + unsigned long state; |
| 20 | 33 | } ____cacheline_aligned_in_smp; |
| 21 | 34 | |
| 35 | + /** |
| 36 | + * @run_work: Used for scheduling a hardware queue run at a later time. |
| 37 | + */ |
| 22 | 38 | struct delayed_work run_work; |
| 39 | + /** @cpumask: Map of available CPUs where this hctx can run. */ |
| 23 | 40 | cpumask_var_t cpumask; |
| 41 | + /** |
| 42 | + * @next_cpu: Used by blk_mq_hctx_next_cpu() for round-robin CPU |
| 43 | + * selection from @cpumask. |
| 44 | + */ |
| 24 | 45 | int next_cpu; |
| 46 | + /** |
| 47 | + * @next_cpu_batch: Counter of how many works left in the batch before |
| 48 | + * changing to the next CPU. |
| 49 | + */ |
| 25 | 50 | int next_cpu_batch; |
| 26 | 51 | |
| 27 | | − unsigned long flags; /* BLK_MQ_F_* flags */ |
| 52 | + /** @flags: BLK_MQ_F_* flags. Defines the behaviour of the queue. */ |
| 53 | + unsigned long flags; |
| 28 | 54 | |
| 55 | + /** |
| 56 | + * @sched_data: Pointer owned by the IO scheduler attached to a request |
| 57 | + * queue. It's up to the IO scheduler how to use this pointer. |
| 58 | + */ |
| 29 | 59 | void *sched_data; |
| 60 | + /** |
| 61 | + * @queue: Pointer to the request queue that owns this hardware context. |
| 62 | + */ |
| 30 | 63 | struct request_queue *queue; |
| 64 | + /** @fq: Queue of requests that need to perform a flush operation. */ |
| 31 | 65 | struct blk_flush_queue *fq; |
| 32 | 66 | |
| 67 | + /** |
| 68 | + * @driver_data: Pointer to data owned by the block driver that created |
| 69 | + * this hctx |
| 70 | + */ |
| 33 | 71 | void *driver_data; |
| 34 | 72 | |
| 73 | + /** |
| 74 | + * @ctx_map: Bitmap for each software queue. If bit is on, there is a |
| 75 | + * pending request in that software queue. |
| 76 | + */ |
| 35 | 77 | struct sbitmap ctx_map; |
| 36 | 78 | |
| 79 | + /** |
| 80 | + * @dispatch_from: Software queue to be used when no scheduler was |
| 81 | + * selected. |
| 82 | + */ |
| 37 | 83 | struct blk_mq_ctx *dispatch_from; |
| 84 | + /** |
| 85 | + * @dispatch_busy: Number used by blk_mq_update_dispatch_busy() to |
| 86 | + * decide if the hw_queue is busy using Exponential Weighted Moving |
| 87 | + * Average algorithm. |
| 88 | + */ |
| 38 | 89 | unsigned int dispatch_busy; |
| 39 | 90 | |
| 91 | + /** @type: HCTX_TYPE_* flags. Type of hardware queue. */ |
| 40 | 92 | unsigned short type; |
| 93 | + /** @nr_ctx: Number of software queues. */ |
| 41 | 94 | unsigned short nr_ctx; |
| 95 | + /** @ctxs: Array of software queues. */ |
| 42 | 96 | struct blk_mq_ctx **ctxs; |
| 43 | 97 | |
| 98 | + /** @dispatch_wait_lock: Lock for dispatch_wait queue. */ |
| 44 | 99 | spinlock_t dispatch_wait_lock; |
| 100 | + /** |
| 101 | + * @dispatch_wait: Waitqueue to put requests when there is no tag |
| 102 | + * available at the moment, to wait for another try in the future. |
| 103 | + */ |
| 45 | 104 | wait_queue_entry_t dispatch_wait; |
| 105 | + |
| 106 | + /** |
| 107 | + * @wait_index: Index of next available dispatch_wait queue to insert |
| 108 | + * requests. |
| 109 | + */ |
| 46 | 110 | atomic_t wait_index; |
| 47 | 111 | |
| 112 | + /** |
| 113 | + * @tags: Tags owned by the block driver. A tag at this set is only |
| 114 | + * assigned when a request is dispatched from a hardware queue. |
| 115 | + */ |
| 48 | 116 | struct blk_mq_tags *tags; |
| 117 | + /** |
| 118 | + * @sched_tags: Tags owned by I/O scheduler. If there is an I/O |
| 119 | + * scheduler associated with a request queue, a tag is assigned when |
| 120 | + * that request is allocated. Else, this member is not used. |
| 121 | + */ |
| 49 | 122 | struct blk_mq_tags *sched_tags; |
| 50 | 123 | |
| 124 | + /** @queued: Number of queued requests. */ |
| 51 | 125 | unsigned long queued; |
| 126 | + /** @run: Number of dispatched requests. */ |
| 52 | 127 | unsigned long run; |
| 53 | 128 | #define BLK_MQ_MAX_DISPATCH_ORDER 7 |
| 129 | + /** @dispatched: Number of dispatch requests by queue. */ |
| 54 | 130 | unsigned long dispatched[BLK_MQ_MAX_DISPATCH_ORDER]; |
| 55 | 131 | |
| 132 | + /** @numa_node: NUMA node the storage adapter has been connected to. */ |
| 56 | 133 | unsigned int numa_node; |
| 134 | + /** @queue_num: Index of this hardware queue. */ |
| 57 | 135 | unsigned int queue_num; |
| 58 | 136 | |
| 137 | + /** |
| 138 | + * @nr_active: Number of active requests. Only used when a tag set is |
| 139 | + * shared across request queues. |
| 140 | + */ |
| 59 | 141 | atomic_t nr_active; |
| 60 | 142 | |
| 143 | + /** @cpuhp_dead: List to store request if some CPU die. */ |
| 61 | 144 | struct hlist_node cpuhp_dead; |
| 145 | + /** @kobj: Kernel object for sysfs. */ |
| 62 | 146 | struct kobject kobj; |
| 63 | 147 | |
| 148 | + /** @poll_considered: Count times blk_poll() was called. */ |
| 64 | 149 | unsigned long poll_considered; |
| 150 | + /** @poll_invoked: Count how many requests blk_poll() polled. */ |
| 65 | 151 | unsigned long poll_invoked; |
| 152 | + /** @poll_success: Count how many polled requests were completed. */ |
| 66 | 153 | unsigned long poll_success; |
| 67 | 154 | |
| 68 | 155 | #ifdef CONFIG_BLK_DEBUG_FS |
| 156 | + /** |
| 157 | + * @debugfs_dir: debugfs directory for this hardware queue. Named |
| 158 | + * as cpu<cpu_number>. |
| 159 | + */ |
| 69 | 160 | struct dentry *debugfs_dir; |
| 161 | + /** @sched_debugfs_dir: debugfs directory for the scheduler. */ |
| 70 | 162 | struct dentry *sched_debugfs_dir; |
| 71 | 163 | #endif |
| 72 | 164 | |
| 165 | + /** @hctx_list: List of all hardware queues. */ |
| 73 | 166 | struct list_head hctx_list; |
| 74 | 167 | |
| 75 | | − /* Must be the last member - see also blk_mq_hw_ctx_size(). */ |
| 168 | + /** |
| 169 | + * @srcu: Sleepable RCU. Use as lock when type of the hardware queue is |
| 170 | + * blocking (BLK_MQ_F_BLOCKING). Must be the last member - see also |
| 171 | + * blk_mq_hw_ctx_size(). |
| 172 | + */ |
| 76 | 173 | struct srcu_struct srcu[0]; |
| 77 | 174 | }; |
| 78 | 175 | |
| 176 | +/** |
| 177 | + * struct blk_mq_queue_map - Map software queues to hardware queues |
| 178 | + * @mq_map: CPU ID to hardware queue index map. This is an array |
| 179 | + * with nr_cpu_ids elements. Each element has a value in the range |
| 180 | + * [@queue_offset, @queue_offset + @nr_queues). |
| 181 | + * @nr_queues: Number of hardware queues to map CPU IDs onto. |
| 182 | + * @queue_offset: First hardware queue to map onto. Used by the PCIe NVMe |
| 183 | + * driver to map each hardware queue type (enum hctx_type) onto a distinct |
| 184 | + * set of hardware queues. |
| 185 | + */ |
| 79 | 186 | struct blk_mq_queue_map { |
| 80 | 187 | unsigned int *mq_map; |
| 81 | 188 | unsigned int nr_queues; |
| 82 | 189 | unsigned int queue_offset; |
| 83 | 190 | }; |
| 84 | 191 | |
| 192 | +/** |
| 193 | + * enum hctx_type - Type of hardware queue |
| 194 | + * @HCTX_TYPE_DEFAULT: All I/O not otherwise accounted for. |
| 195 | + * @HCTX_TYPE_READ: Just for READ I/O. |
| 196 | + * @HCTX_TYPE_POLL: Polled I/O of any kind. |
| 197 | + * @HCTX_MAX_TYPES: Number of types of hctx. |
| 198 | + */ |
| 85 | 199 | enum hctx_type { |
| 86 | | − HCTX_TYPE_DEFAULT, /* all I/O not otherwise accounted for */ |
| 87 | | − HCTX_TYPE_READ, /* just for READ I/O */ |
| 88 | | − HCTX_TYPE_POLL, /* polled I/O of any kind */ |
| 200 | + HCTX_TYPE_DEFAULT, |
| 201 | + HCTX_TYPE_READ, |
| 202 | + HCTX_TYPE_POLL, |
| 89 | 203 | |
| 90 | 204 | HCTX_MAX_TYPES, |
| 91 | 205 | }; |
| 92 | 206 | |
| 207 | +/** |
| 208 | + * struct blk_mq_tag_set - tag set that can be shared between request queues |
| 209 | + * @map: One or more ctx -> hctx mappings. One map exists for each |
| 210 | + * hardware queue type (enum hctx_type) that the driver wishes |
| 211 | + * to support. There are no restrictions on maps being of the |
| 212 | + * same size, and it's perfectly legal to share maps between |
| 213 | + * types. |
| 214 | + * @nr_maps: Number of elements in the @map array. A number in the range |
| 215 | + * [1, HCTX_MAX_TYPES]. |
| 216 | + * @ops: Pointers to functions that implement block driver behavior. |
| 217 | + * @nr_hw_queues: Number of hardware queues supported by the block driver that |
| 218 | + * owns this data structure. |
| 219 | + * @queue_depth: Number of tags per hardware queue, reserved tags included. |
| 220 | + * @reserved_tags: Number of tags to set aside for BLK_MQ_REQ_RESERVED tag |
| 221 | + * allocations. |
| 222 | + * @cmd_size: Number of additional bytes to allocate per request. The block |
| 223 | + * driver owns these additional bytes. |
| 224 | + * @numa_node: NUMA node the storage adapter has been connected to. |
| 225 | + * @timeout: Request processing timeout in jiffies. |
| 226 | + * @flags: Zero or more BLK_MQ_F_* flags. |
| 227 | + * @driver_data: Pointer to data owned by the block driver that created this |
| 228 | + * tag set. |
| 229 | + * @tags: Tag sets. One tag set per hardware queue. Has @nr_hw_queues |
| 230 | + * elements. |
| 231 | + * @tag_list_lock: Serializes tag_list accesses. |
| 232 | + * @tag_list: List of the request queues that use this tag set. See also |
| 233 | + * request_queue.tag_set_list. |
| 234 | + */ |
| 93 | 235 | struct blk_mq_tag_set { |
| 94 | | − /* |
| 95 | | − * map[] holds ctx -> hctx mappings, one map exists for each type |
| 96 | | − * that the driver wishes to support. There are no restrictions |
| 97 | | − * on maps being of the same size, and it's perfectly legal to |
| 98 | | − * share maps between types. |
| 99 | | − */ |
| 100 | 236 | struct blk_mq_queue_map map[HCTX_MAX_TYPES]; |
| 101 | | − unsigned int nr_maps; /* nr entries in map[] */ |
| 237 | + unsigned int nr_maps; |
| 102 | 238 | const struct blk_mq_ops *ops; |
| 103 | | − unsigned int nr_hw_queues; /* nr hw queues across maps */ |
| 104 | | − unsigned int queue_depth; /* max hw supported */ |
| 239 | + unsigned int nr_hw_queues; |
| 240 | + unsigned int queue_depth; |
| 105 | 241 | unsigned int reserved_tags; |
| 106 | | − unsigned int cmd_size; /* per-request extra data */ |
| 242 | + unsigned int cmd_size; |
| 107 | 243 | int numa_node; |
| 108 | 244 | unsigned int timeout; |
| 109 | | − unsigned int flags; /* BLK_MQ_F_* */ |
| 245 | + unsigned int flags; |
| 110 | 246 | void *driver_data; |
| 111 | 247 | |
| 112 | 248 | struct blk_mq_tags **tags; |
| @@ -115,6 +251,12 @@ struct blk_mq_tag_set { · 2 unmodified lines |
| 115 | 251 | struct list_head tag_list; |
| 116 | 252 | }; |
| 117 | 253 | |
| 254 | +/** |
| 255 | + * struct blk_mq_queue_data - Data about a request inserted in a queue |
| 256 | + * |
| 257 | + * @rq: Request pointer. |
| 258 | + * @last: If it is the last request in the queue. |
| 259 | + */ |
| 118 | 260 | struct blk_mq_queue_data { |
| 119 | 261 | struct request *rq; |
| 120 | 262 | bool last; |
| @@ -142,81 +284,101 @@ typedef bool (busy_fn)(struct request_queue *); · 21 unmodified lines |
| 142 | 284 | typedef void (complete_fn)(struct request *); |
| 143 | 285 | typedef void (cleanup_rq_fn)(struct request *); |
| 144 | 286 | |
| 145 | | − |
| 287 | +/** |
| 288 | + * struct blk_mq_ops - Callback functions that implements block driver |
| 289 | + * behaviour. |
| 290 | + */ |
| 146 | 291 | struct blk_mq_ops { |
| 147 | | − /* |
| 148 | | − * Queue request |
| 292 | + /** |
| 293 | + * @queue_rq: Queue a new request from block IO. |
| 149 | 294 | */ |
| 150 | 295 | queue_rq_fn *queue_rq; |
| 151 | 296 | |
| 152 | | − /* |
| 153 | | − * If a driver uses bd->last to judge when to submit requests to |
| 154 | | − * hardware, it must define this function. In case of errors that |
| 155 | | − * make us stop issuing further requests, this hook serves the |
| 297 | + /** |
| 298 | + * @commit_rqs: If a driver uses bd->last to judge when to submit |
| 299 | + * requests to hardware, it must define this function. In case of errors |
| 300 | + * that make us stop issuing further requests, this hook serves the |
| 156 | 301 | * purpose of kicking the hardware (which the last request otherwise |
| 157 | 302 | * would have done). |
| 158 | 303 | */ |
| 159 | 304 | commit_rqs_fn *commit_rqs; |
| 160 | 305 | |
| 161 | | − /* |
| 162 | | − * Reserve budget before queue request, once .queue_rq is |
| 306 | + /** |
| 307 | + * @get_budget: Reserve budget before queue request, once .queue_rq is |
| 163 | 308 | * run, it is driver's responsibility to release the |
| 164 | 309 | * reserved budget. Also we have to handle failure case |
| 165 | 310 | * of .get_budget for avoiding I/O deadlock. |
| 166 | 311 | */ |
| 167 | 312 | get_budget_fn *get_budget; |
| 313 | + /** |
| 314 | + * @put_budget: Release the reserved budget. |
| 315 | + */ |
| 168 | 316 | put_budget_fn *put_budget; |
| 169 | 317 | |
| 170 | | − /* |
| 171 | | − * Called on request timeout |
| 318 | + /** |
| 319 | + * @timeout: Called on request timeout. |
| 172 | 320 | */ |
| 173 | 321 | timeout_fn *timeout; |
| 174 | 322 | |
| 175 | | − /* |
| 176 | | − * Called to poll for completion of a specific tag. |
| 323 | + /** |
| 324 | + * @poll: Called to poll for completion of a specific tag. |
| 177 | 325 | */ |
| 178 | 326 | poll_fn *poll; |
| 179 | 327 | |
| 328 | + /** |
| 329 | + * @complete: Mark the request as complete. |
| 330 | + */ |
| 180 | 331 | complete_fn *complete; |
| 181 | 332 | |
| 182 | | − /* |
| 183 | | − * Called when the block layer side of a hardware queue has been |
| 184 | | − * set up, allowing the driver to allocate/init matching structures. |
| 185 | | − * Ditto for exit/teardown. |
| 333 | + /** |
| 334 | + * @init_hctx: Called when the block layer side of a hardware queue has |
| 335 | + * been set up, allowing the driver to allocate/init matching |
| 336 | + * structures. |
| 186 | 337 | */ |
| 187 | 338 | init_hctx_fn *init_hctx; |
| 339 | + /** |
| 340 | + * @exit_hctx: Ditto for exit/teardown. |
| 341 | + */ |
| 188 | 342 | exit_hctx_fn *exit_hctx; |
| 189 | 343 | |
| 190 | | − /* |
| 191 | | − * Called for every command allocated by the block layer to allow |
| 192 | | − * the driver to set up driver specific data. |
| 344 | + /** |
| 345 | + * @init_request: Called for every command allocated by the block layer |
| 346 | + * to allow the driver to set up driver specific data. |
| 193 | 347 | * |
| 194 | 348 | * Tag greater than or equal to queue_depth is for setting up |
| 195 | 349 | * flush request. |
| 196 | | − * |
| 197 | | − * Ditto for exit/teardown. |
| 198 | 350 | */ |
| 199 | 351 | init_request_fn *init_request; |
| 352 | + /** |
| 353 | + * @exit_request: Ditto for exit/teardown. |
| 354 | + */ |
| 200 | 355 | exit_request_fn *exit_request; |
| 201 | | − /* Called from inside blk_get_request() */ |
| 356 | + |
| 357 | + /** |
| 358 | + * @initialize_rq_fn: Called from inside blk_get_request(). |
| 359 | + */ |
| 202 | 360 | void (*initialize_rq_fn)(struct request *rq); |
| 203 | 361 | |
| 204 | | − /* |
| 205 | | − * Called before freeing one request which isn't completed yet, |
| 206 | | − * and usually for freeing the driver private data |
| 362 | + /** |
| 363 | + * @cleanup_rq: Called before freeing one request which isn't completed |
| 364 | + * yet, and usually for freeing the driver private data. |
| 207 | 365 | */ |
| 208 | 366 | cleanup_rq_fn *cleanup_rq; |
| 209 | 367 | |
| 210 | | − /* |
| 211 | | − * If set, returns whether or not this queue currently is busy |
| 368 | + /** |
| 369 | + * @busy: If set, returns whether or not this queue currently is busy. |
| 212 | 370 | */ |
| 213 | 371 | busy_fn *busy; |
| 214 | 372 | |
| 373 | + /** |
| 374 | + * @map_queues: This allows drivers specify their own queue mapping by |
| 375 | + * overriding the setup-time function that builds the mq_map. |
| 376 | + */ |
| 215 | 377 | map_queues_fn *map_queues; |
| 216 | 378 | |
| 217 | 379 | #ifdef CONFIG_BLK_DEBUG_FS |
| 218 | | − /* |
| 219 | | − * Used by the debugfs implementation to show driver-specific |
| 380 | + /** |
| 381 | + * @show_rq: Used by the debugfs implementation to show driver-specific |
| 220 | 382 | * information about a request. |
| 221 | 383 | */ |
| 222 | 384 | void (*show_rq)(struct seq_file *m, struct request *rq); |
| @@ -262,7 +424,6 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set); · 39 unmodified lines |
| 262 | 424 | void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule); |
| 263 | 425 | |
| 264 | 426 | void blk_mq_free_request(struct request *rq); |
| 265 | | −bool blk_mq_can_queue(struct blk_mq_hw_ctx *); |
| 266 | 427 | |
| 267 | 428 | bool blk_mq_queue_inflight(struct request_queue *q); |
| 268 | 429 | |
| @@ -301,9 +462,25 @@ static inline u16 blk_mq_unique_tag_to_tag(u32 unique_tag) · 32 unmodified lines |
| 301 | 462 | return unique_tag & BLK_MQ_UNIQUE_TAG_MASK; |
| 302 | 463 | } |
| 303 | 464 | |
| 465 | +/** |
| 466 | + * blk_mq_rq_state() - read the current MQ_RQ_* state of a request |
| 467 | + * @rq: target request. |
| 468 | + */ |
| 469 | +static inline enum mq_rq_state blk_mq_rq_state(struct request *rq) |
| 470 | +{ |
| 471 | + return READ_ONCE(rq->state); |
| 472 | +} |
| 473 | + |
| 474 | +static inline int blk_mq_request_started(struct request *rq) |
| 475 | +{ |
| 476 | + return blk_mq_rq_state(rq) != MQ_RQ_IDLE; |
| 477 | +} |
| 478 | + |
| 479 | +static inline int blk_mq_request_completed(struct request *rq) |
| 480 | +{ |
| 481 | + return blk_mq_rq_state(rq) == MQ_RQ_COMPLETE; |
| 482 | +} |
| 304 | 483 | |
| 305 | | −int blk_mq_request_started(struct request *rq); |
| 306 | | −int blk_mq_request_completed(struct request *rq); |
| 307 | 484 | void blk_mq_start_request(struct request *rq); |
| 308 | 485 | void blk_mq_end_request(struct request *rq, blk_status_t error); |
| 309 | 486 | void __blk_mq_end_request(struct request *rq, blk_status_t error); |
| @@ -324,7 +501,7 @@ void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async); · 14 unmodified lines |
| 324 | 501 | void blk_mq_quiesce_queue(struct request_queue *q); |
| 325 | 502 | void blk_mq_unquiesce_queue(struct request_queue *q); |
| 326 | 503 | void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs); |
| 327 | | −bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async); |
| 504 | +void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async); |
| 328 | 505 | void blk_mq_run_hw_queues(struct request_queue *q, bool async); |
| 329 | 506 | void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset, |
| 330 | 507 | busy_tag_iter_fn *fn, void *priv); |
| @@ -343,14 +520,29 @@ void blk_mq_quiesce_queue_nowait(struct request_queue *q); · 12 unmodified lines |
| 343 | 520 | |
| 344 | 521 | unsigned int blk_mq_rq_cpu(struct request *rq); |
| 345 | 522 | |
| 346 | | −/* |
| 523 | +/** |
| 524 | + * blk_mq_rq_from_pdu - cast a PDU to a request |
| 525 | + * @pdu: the PDU (Protocol Data Unit) to be casted |
| 526 | + * |
| 527 | + * Return: request |
| 528 | + * |
| 347 | 529 | * Driver command data is immediately after the request. So subtract request |
| 348 | | − * size to get back to the original request, add request size to get the PDU. |
| 530 | + * size to get back to the original request. |
| 349 | 531 | */ |
| 350 | 532 | static inline struct request *blk_mq_rq_from_pdu(void *pdu) |
| 351 | 533 | { |
| 352 | 534 | return pdu - sizeof(struct request); |
| 353 | 535 | } |
| 536 | + |
| 537 | +/** |
| 538 | + * blk_mq_rq_to_pdu - cast a request to a PDU |
| 539 | + * @rq: the request to be casted |
| 540 | + * |
| 541 | + * Return: pointer to the PDU |
| 542 | + * |
| 543 | + * Driver command data is immediately after the request. So add request to get |
| 544 | + * the PDU. |
| 545 | + */ |
| 354 | 546 | static inline void *blk_mq_rq_to_pdu(struct request *rq) |
| 355 | 547 | { |
| 356 | 548 | return rq + 1; |