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1 | /* | |
2 | * Copyright (C) 1991, 1992 Linus Torvalds | |
3 | * Copyright (C) 1994, Karl Keyte: Added support for disk statistics | |
4 | * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
5 | * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> | |
6 | * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> | |
7 | * - July2000 | |
8 | * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 | |
9 | */ | |
10 | ||
11 | /* | |
12 | * This handles all read/write requests to block devices | |
13 | */ | |
14 | #include <linux/kernel.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/backing-dev.h> | |
17 | #include <linux/bio.h> | |
18 | #include <linux/blkdev.h> | |
19 | #include <linux/highmem.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/kernel_stat.h> | |
22 | #include <linux/string.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/completion.h> | |
25 | #include <linux/slab.h> | |
26 | #include <linux/swap.h> | |
27 | #include <linux/writeback.h> | |
28 | #include <linux/task_io_accounting_ops.h> | |
29 | #include <linux/fault-inject.h> | |
30 | ||
31 | #define CREATE_TRACE_POINTS | |
32 | #include <trace/events/block.h> | |
33 | ||
34 | #include "blk.h" | |
35 | ||
36 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_remap); | |
37 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); | |
38 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); | |
39 | ||
40 | static int __make_request(struct request_queue *q, struct bio *bio); | |
41 | ||
42 | /* | |
43 | * For the allocated request tables | |
44 | */ | |
45 | static struct kmem_cache *request_cachep; | |
46 | ||
47 | /* | |
48 | * For queue allocation | |
49 | */ | |
50 | struct kmem_cache *blk_requestq_cachep; | |
51 | ||
52 | /* | |
53 | * Controlling structure to kblockd | |
54 | */ | |
55 | static struct workqueue_struct *kblockd_workqueue; | |
56 | ||
57 | static void drive_stat_acct(struct request *rq, int new_io) | |
58 | { | |
59 | struct hd_struct *part; | |
60 | int rw = rq_data_dir(rq); | |
61 | int cpu; | |
62 | ||
63 | if (!blk_do_io_stat(rq)) | |
64 | return; | |
65 | ||
66 | cpu = part_stat_lock(); | |
67 | part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); | |
68 | ||
69 | if (!new_io) | |
70 | part_stat_inc(cpu, part, merges[rw]); | |
71 | else { | |
72 | part_round_stats(cpu, part); | |
73 | part_inc_in_flight(part, rw); | |
74 | } | |
75 | ||
76 | part_stat_unlock(); | |
77 | } | |
78 | ||
79 | void blk_queue_congestion_threshold(struct request_queue *q) | |
80 | { | |
81 | int nr; | |
82 | ||
83 | nr = q->nr_requests - (q->nr_requests / 8) + 1; | |
84 | if (nr > q->nr_requests) | |
85 | nr = q->nr_requests; | |
86 | q->nr_congestion_on = nr; | |
87 | ||
88 | nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; | |
89 | if (nr < 1) | |
90 | nr = 1; | |
91 | q->nr_congestion_off = nr; | |
92 | } | |
93 | ||
94 | /** | |
95 | * blk_get_backing_dev_info - get the address of a queue's backing_dev_info | |
96 | * @bdev: device | |
97 | * | |
98 | * Locates the passed device's request queue and returns the address of its | |
99 | * backing_dev_info | |
100 | * | |
101 | * Will return NULL if the request queue cannot be located. | |
102 | */ | |
103 | struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) | |
104 | { | |
105 | struct backing_dev_info *ret = NULL; | |
106 | struct request_queue *q = bdev_get_queue(bdev); | |
107 | ||
108 | if (q) | |
109 | ret = &q->backing_dev_info; | |
110 | return ret; | |
111 | } | |
112 | EXPORT_SYMBOL(blk_get_backing_dev_info); | |
113 | ||
114 | void blk_rq_init(struct request_queue *q, struct request *rq) | |
115 | { | |
116 | memset(rq, 0, sizeof(*rq)); | |
117 | ||
118 | INIT_LIST_HEAD(&rq->queuelist); | |
119 | INIT_LIST_HEAD(&rq->timeout_list); | |
120 | rq->cpu = -1; | |
121 | rq->q = q; | |
122 | rq->__sector = (sector_t) -1; | |
123 | INIT_HLIST_NODE(&rq->hash); | |
124 | RB_CLEAR_NODE(&rq->rb_node); | |
125 | rq->cmd = rq->__cmd; | |
126 | rq->cmd_len = BLK_MAX_CDB; | |
127 | rq->tag = -1; | |
128 | rq->ref_count = 1; | |
129 | rq->start_time = jiffies; | |
130 | set_start_time_ns(rq); | |
131 | } | |
132 | EXPORT_SYMBOL(blk_rq_init); | |
133 | ||
134 | static void req_bio_endio(struct request *rq, struct bio *bio, | |
135 | unsigned int nbytes, int error) | |
136 | { | |
137 | struct request_queue *q = rq->q; | |
138 | ||
139 | if (&q->bar_rq != rq) { | |
140 | if (error) | |
141 | clear_bit(BIO_UPTODATE, &bio->bi_flags); | |
142 | else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) | |
143 | error = -EIO; | |
144 | ||
145 | if (unlikely(nbytes > bio->bi_size)) { | |
146 | printk(KERN_ERR "%s: want %u bytes done, %u left\n", | |
147 | __func__, nbytes, bio->bi_size); | |
148 | nbytes = bio->bi_size; | |
149 | } | |
150 | ||
151 | if (unlikely(rq->cmd_flags & REQ_QUIET)) | |
152 | set_bit(BIO_QUIET, &bio->bi_flags); | |
153 | ||
154 | bio->bi_size -= nbytes; | |
155 | bio->bi_sector += (nbytes >> 9); | |
156 | ||
157 | if (bio_integrity(bio)) | |
158 | bio_integrity_advance(bio, nbytes); | |
159 | ||
160 | if (bio->bi_size == 0) | |
161 | bio_endio(bio, error); | |
162 | } else { | |
163 | ||
164 | /* | |
165 | * Okay, this is the barrier request in progress, just | |
166 | * record the error; | |
167 | */ | |
168 | if (error && !q->orderr) | |
169 | q->orderr = error; | |
170 | } | |
171 | } | |
172 | ||
173 | void blk_dump_rq_flags(struct request *rq, char *msg) | |
174 | { | |
175 | int bit; | |
176 | ||
177 | printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg, | |
178 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, | |
179 | rq->cmd_flags); | |
180 | ||
181 | printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", | |
182 | (unsigned long long)blk_rq_pos(rq), | |
183 | blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); | |
184 | printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n", | |
185 | rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq)); | |
186 | ||
187 | if (rq->cmd_type == REQ_TYPE_BLOCK_PC) { | |
188 | printk(KERN_INFO " cdb: "); | |
189 | for (bit = 0; bit < BLK_MAX_CDB; bit++) | |
190 | printk("%02x ", rq->cmd[bit]); | |
191 | printk("\n"); | |
192 | } | |
193 | } | |
194 | EXPORT_SYMBOL(blk_dump_rq_flags); | |
195 | ||
196 | /* | |
197 | * "plug" the device if there are no outstanding requests: this will | |
198 | * force the transfer to start only after we have put all the requests | |
199 | * on the list. | |
200 | * | |
201 | * This is called with interrupts off and no requests on the queue and | |
202 | * with the queue lock held. | |
203 | */ | |
204 | void blk_plug_device(struct request_queue *q) | |
205 | { | |
206 | WARN_ON(!irqs_disabled()); | |
207 | ||
208 | /* | |
209 | * don't plug a stopped queue, it must be paired with blk_start_queue() | |
210 | * which will restart the queueing | |
211 | */ | |
212 | if (blk_queue_stopped(q)) | |
213 | return; | |
214 | ||
215 | if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) { | |
216 | mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); | |
217 | trace_block_plug(q); | |
218 | } | |
219 | } | |
220 | EXPORT_SYMBOL(blk_plug_device); | |
221 | ||
222 | /** | |
223 | * blk_plug_device_unlocked - plug a device without queue lock held | |
224 | * @q: The &struct request_queue to plug | |
225 | * | |
226 | * Description: | |
227 | * Like @blk_plug_device(), but grabs the queue lock and disables | |
228 | * interrupts. | |
229 | **/ | |
230 | void blk_plug_device_unlocked(struct request_queue *q) | |
231 | { | |
232 | unsigned long flags; | |
233 | ||
234 | spin_lock_irqsave(q->queue_lock, flags); | |
235 | blk_plug_device(q); | |
236 | spin_unlock_irqrestore(q->queue_lock, flags); | |
237 | } | |
238 | EXPORT_SYMBOL(blk_plug_device_unlocked); | |
239 | ||
240 | /* | |
241 | * remove the queue from the plugged list, if present. called with | |
242 | * queue lock held and interrupts disabled. | |
243 | */ | |
244 | int blk_remove_plug(struct request_queue *q) | |
245 | { | |
246 | WARN_ON(!irqs_disabled()); | |
247 | ||
248 | if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q)) | |
249 | return 0; | |
250 | ||
251 | del_timer(&q->unplug_timer); | |
252 | return 1; | |
253 | } | |
254 | EXPORT_SYMBOL(blk_remove_plug); | |
255 | ||
256 | /* | |
257 | * remove the plug and let it rip.. | |
258 | */ | |
259 | void __generic_unplug_device(struct request_queue *q) | |
260 | { | |
261 | if (unlikely(blk_queue_stopped(q))) | |
262 | return; | |
263 | if (!blk_remove_plug(q) && !blk_queue_nonrot(q)) | |
264 | return; | |
265 | ||
266 | q->request_fn(q); | |
267 | } | |
268 | ||
269 | /** | |
270 | * generic_unplug_device - fire a request queue | |
271 | * @q: The &struct request_queue in question | |
272 | * | |
273 | * Description: | |
274 | * Linux uses plugging to build bigger requests queues before letting | |
275 | * the device have at them. If a queue is plugged, the I/O scheduler | |
276 | * is still adding and merging requests on the queue. Once the queue | |
277 | * gets unplugged, the request_fn defined for the queue is invoked and | |
278 | * transfers started. | |
279 | **/ | |
280 | void generic_unplug_device(struct request_queue *q) | |
281 | { | |
282 | if (blk_queue_plugged(q)) { | |
283 | spin_lock_irq(q->queue_lock); | |
284 | __generic_unplug_device(q); | |
285 | spin_unlock_irq(q->queue_lock); | |
286 | } | |
287 | } | |
288 | EXPORT_SYMBOL(generic_unplug_device); | |
289 | ||
290 | static void blk_backing_dev_unplug(struct backing_dev_info *bdi, | |
291 | struct page *page) | |
292 | { | |
293 | struct request_queue *q = bdi->unplug_io_data; | |
294 | ||
295 | blk_unplug(q); | |
296 | } | |
297 | ||
298 | void blk_unplug_work(struct work_struct *work) | |
299 | { | |
300 | struct request_queue *q = | |
301 | container_of(work, struct request_queue, unplug_work); | |
302 | ||
303 | trace_block_unplug_io(q); | |
304 | q->unplug_fn(q); | |
305 | } | |
306 | ||
307 | void blk_unplug_timeout(unsigned long data) | |
308 | { | |
309 | struct request_queue *q = (struct request_queue *)data; | |
310 | ||
311 | trace_block_unplug_timer(q); | |
312 | kblockd_schedule_work(q, &q->unplug_work); | |
313 | } | |
314 | ||
315 | void blk_unplug(struct request_queue *q) | |
316 | { | |
317 | /* | |
318 | * devices don't necessarily have an ->unplug_fn defined | |
319 | */ | |
320 | if (q->unplug_fn) { | |
321 | trace_block_unplug_io(q); | |
322 | q->unplug_fn(q); | |
323 | } | |
324 | } | |
325 | EXPORT_SYMBOL(blk_unplug); | |
326 | ||
327 | /** | |
328 | * blk_start_queue - restart a previously stopped queue | |
329 | * @q: The &struct request_queue in question | |
330 | * | |
331 | * Description: | |
332 | * blk_start_queue() will clear the stop flag on the queue, and call | |
333 | * the request_fn for the queue if it was in a stopped state when | |
334 | * entered. Also see blk_stop_queue(). Queue lock must be held. | |
335 | **/ | |
336 | void blk_start_queue(struct request_queue *q) | |
337 | { | |
338 | WARN_ON(!irqs_disabled()); | |
339 | ||
340 | queue_flag_clear(QUEUE_FLAG_STOPPED, q); | |
341 | __blk_run_queue(q); | |
342 | } | |
343 | EXPORT_SYMBOL(blk_start_queue); | |
344 | ||
345 | /** | |
346 | * blk_stop_queue - stop a queue | |
347 | * @q: The &struct request_queue in question | |
348 | * | |
349 | * Description: | |
350 | * The Linux block layer assumes that a block driver will consume all | |
351 | * entries on the request queue when the request_fn strategy is called. | |
352 | * Often this will not happen, because of hardware limitations (queue | |
353 | * depth settings). If a device driver gets a 'queue full' response, | |
354 | * or if it simply chooses not to queue more I/O at one point, it can | |
355 | * call this function to prevent the request_fn from being called until | |
356 | * the driver has signalled it's ready to go again. This happens by calling | |
357 | * blk_start_queue() to restart queue operations. Queue lock must be held. | |
358 | **/ | |
359 | void blk_stop_queue(struct request_queue *q) | |
360 | { | |
361 | blk_remove_plug(q); | |
362 | queue_flag_set(QUEUE_FLAG_STOPPED, q); | |
363 | } | |
364 | EXPORT_SYMBOL(blk_stop_queue); | |
365 | ||
366 | /** | |
367 | * blk_sync_queue - cancel any pending callbacks on a queue | |
368 | * @q: the queue | |
369 | * | |
370 | * Description: | |
371 | * The block layer may perform asynchronous callback activity | |
372 | * on a queue, such as calling the unplug function after a timeout. | |
373 | * A block device may call blk_sync_queue to ensure that any | |
374 | * such activity is cancelled, thus allowing it to release resources | |
375 | * that the callbacks might use. The caller must already have made sure | |
376 | * that its ->make_request_fn will not re-add plugging prior to calling | |
377 | * this function. | |
378 | * | |
379 | */ | |
380 | void blk_sync_queue(struct request_queue *q) | |
381 | { | |
382 | del_timer_sync(&q->unplug_timer); | |
383 | del_timer_sync(&q->timeout); | |
384 | cancel_work_sync(&q->unplug_work); | |
385 | throtl_shutdown_timer_wq(q); | |
386 | } | |
387 | EXPORT_SYMBOL(blk_sync_queue); | |
388 | ||
389 | /** | |
390 | * __blk_run_queue - run a single device queue | |
391 | * @q: The queue to run | |
392 | * | |
393 | * Description: | |
394 | * See @blk_run_queue. This variant must be called with the queue lock | |
395 | * held and interrupts disabled. | |
396 | * | |
397 | */ | |
398 | void __blk_run_queue(struct request_queue *q) | |
399 | { | |
400 | blk_remove_plug(q); | |
401 | ||
402 | if (unlikely(blk_queue_stopped(q))) | |
403 | return; | |
404 | ||
405 | if (elv_queue_empty(q)) | |
406 | return; | |
407 | ||
408 | /* | |
409 | * Only recurse once to avoid overrunning the stack, let the unplug | |
410 | * handling reinvoke the handler shortly if we already got there. | |
411 | */ | |
412 | if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { | |
413 | q->request_fn(q); | |
414 | queue_flag_clear(QUEUE_FLAG_REENTER, q); | |
415 | } else { | |
416 | queue_flag_set(QUEUE_FLAG_PLUGGED, q); | |
417 | kblockd_schedule_work(q, &q->unplug_work); | |
418 | } | |
419 | } | |
420 | EXPORT_SYMBOL(__blk_run_queue); | |
421 | ||
422 | /** | |
423 | * blk_run_queue - run a single device queue | |
424 | * @q: The queue to run | |
425 | * | |
426 | * Description: | |
427 | * Invoke request handling on this queue, if it has pending work to do. | |
428 | * May be used to restart queueing when a request has completed. | |
429 | */ | |
430 | void blk_run_queue(struct request_queue *q) | |
431 | { | |
432 | unsigned long flags; | |
433 | ||
434 | spin_lock_irqsave(q->queue_lock, flags); | |
435 | __blk_run_queue(q); | |
436 | spin_unlock_irqrestore(q->queue_lock, flags); | |
437 | } | |
438 | EXPORT_SYMBOL(blk_run_queue); | |
439 | ||
440 | void blk_put_queue(struct request_queue *q) | |
441 | { | |
442 | kobject_put(&q->kobj); | |
443 | } | |
444 | ||
445 | void blk_cleanup_queue(struct request_queue *q) | |
446 | { | |
447 | /* | |
448 | * We know we have process context here, so we can be a little | |
449 | * cautious and ensure that pending block actions on this device | |
450 | * are done before moving on. Going into this function, we should | |
451 | * not have processes doing IO to this device. | |
452 | */ | |
453 | blk_sync_queue(q); | |
454 | ||
455 | del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer); | |
456 | mutex_lock(&q->sysfs_lock); | |
457 | queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q); | |
458 | mutex_unlock(&q->sysfs_lock); | |
459 | ||
460 | if (q->elevator) | |
461 | elevator_exit(q->elevator); | |
462 | ||
463 | blk_throtl_exit(q); | |
464 | ||
465 | blk_put_queue(q); | |
466 | } | |
467 | EXPORT_SYMBOL(blk_cleanup_queue); | |
468 | ||
469 | static int blk_init_free_list(struct request_queue *q) | |
470 | { | |
471 | struct request_list *rl = &q->rq; | |
472 | ||
473 | if (unlikely(rl->rq_pool)) | |
474 | return 0; | |
475 | ||
476 | rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; | |
477 | rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; | |
478 | rl->elvpriv = 0; | |
479 | init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); | |
480 | init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); | |
481 | ||
482 | rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, | |
483 | mempool_free_slab, request_cachep, q->node); | |
484 | ||
485 | if (!rl->rq_pool) | |
486 | return -ENOMEM; | |
487 | ||
488 | return 0; | |
489 | } | |
490 | ||
491 | struct request_queue *blk_alloc_queue(gfp_t gfp_mask) | |
492 | { | |
493 | return blk_alloc_queue_node(gfp_mask, -1); | |
494 | } | |
495 | EXPORT_SYMBOL(blk_alloc_queue); | |
496 | ||
497 | struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) | |
498 | { | |
499 | struct request_queue *q; | |
500 | int err; | |
501 | ||
502 | q = kmem_cache_alloc_node(blk_requestq_cachep, | |
503 | gfp_mask | __GFP_ZERO, node_id); | |
504 | if (!q) | |
505 | return NULL; | |
506 | ||
507 | q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; | |
508 | q->backing_dev_info.unplug_io_data = q; | |
509 | q->backing_dev_info.ra_pages = | |
510 | (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; | |
511 | q->backing_dev_info.state = 0; | |
512 | q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; | |
513 | q->backing_dev_info.name = "block"; | |
514 | ||
515 | err = bdi_init(&q->backing_dev_info); | |
516 | if (err) { | |
517 | kmem_cache_free(blk_requestq_cachep, q); | |
518 | return NULL; | |
519 | } | |
520 | ||
521 | if (blk_throtl_init(q)) { | |
522 | kmem_cache_free(blk_requestq_cachep, q); | |
523 | return NULL; | |
524 | } | |
525 | ||
526 | setup_timer(&q->backing_dev_info.laptop_mode_wb_timer, | |
527 | laptop_mode_timer_fn, (unsigned long) q); | |
528 | init_timer(&q->unplug_timer); | |
529 | setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); | |
530 | INIT_LIST_HEAD(&q->timeout_list); | |
531 | INIT_WORK(&q->unplug_work, blk_unplug_work); | |
532 | ||
533 | kobject_init(&q->kobj, &blk_queue_ktype); | |
534 | ||
535 | mutex_init(&q->sysfs_lock); | |
536 | spin_lock_init(&q->__queue_lock); | |
537 | ||
538 | return q; | |
539 | } | |
540 | EXPORT_SYMBOL(blk_alloc_queue_node); | |
541 | ||
542 | /** | |
543 | * blk_init_queue - prepare a request queue for use with a block device | |
544 | * @rfn: The function to be called to process requests that have been | |
545 | * placed on the queue. | |
546 | * @lock: Request queue spin lock | |
547 | * | |
548 | * Description: | |
549 | * If a block device wishes to use the standard request handling procedures, | |
550 | * which sorts requests and coalesces adjacent requests, then it must | |
551 | * call blk_init_queue(). The function @rfn will be called when there | |
552 | * are requests on the queue that need to be processed. If the device | |
553 | * supports plugging, then @rfn may not be called immediately when requests | |
554 | * are available on the queue, but may be called at some time later instead. | |
555 | * Plugged queues are generally unplugged when a buffer belonging to one | |
556 | * of the requests on the queue is needed, or due to memory pressure. | |
557 | * | |
558 | * @rfn is not required, or even expected, to remove all requests off the | |
559 | * queue, but only as many as it can handle at a time. If it does leave | |
560 | * requests on the queue, it is responsible for arranging that the requests | |
561 | * get dealt with eventually. | |
562 | * | |
563 | * The queue spin lock must be held while manipulating the requests on the | |
564 | * request queue; this lock will be taken also from interrupt context, so irq | |
565 | * disabling is needed for it. | |
566 | * | |
567 | * Function returns a pointer to the initialized request queue, or %NULL if | |
568 | * it didn't succeed. | |
569 | * | |
570 | * Note: | |
571 | * blk_init_queue() must be paired with a blk_cleanup_queue() call | |
572 | * when the block device is deactivated (such as at module unload). | |
573 | **/ | |
574 | ||
575 | struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) | |
576 | { | |
577 | return blk_init_queue_node(rfn, lock, -1); | |
578 | } | |
579 | EXPORT_SYMBOL(blk_init_queue); | |
580 | ||
581 | struct request_queue * | |
582 | blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) | |
583 | { | |
584 | struct request_queue *uninit_q, *q; | |
585 | ||
586 | uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id); | |
587 | if (!uninit_q) | |
588 | return NULL; | |
589 | ||
590 | q = blk_init_allocated_queue_node(uninit_q, rfn, lock, node_id); | |
591 | if (!q) | |
592 | blk_cleanup_queue(uninit_q); | |
593 | ||
594 | return q; | |
595 | } | |
596 | EXPORT_SYMBOL(blk_init_queue_node); | |
597 | ||
598 | struct request_queue * | |
599 | blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, | |
600 | spinlock_t *lock) | |
601 | { | |
602 | return blk_init_allocated_queue_node(q, rfn, lock, -1); | |
603 | } | |
604 | EXPORT_SYMBOL(blk_init_allocated_queue); | |
605 | ||
606 | struct request_queue * | |
607 | blk_init_allocated_queue_node(struct request_queue *q, request_fn_proc *rfn, | |
608 | spinlock_t *lock, int node_id) | |
609 | { | |
610 | if (!q) | |
611 | return NULL; | |
612 | ||
613 | q->node = node_id; | |
614 | if (blk_init_free_list(q)) | |
615 | return NULL; | |
616 | ||
617 | q->request_fn = rfn; | |
618 | q->prep_rq_fn = NULL; | |
619 | q->unprep_rq_fn = NULL; | |
620 | q->unplug_fn = generic_unplug_device; | |
621 | q->queue_flags = QUEUE_FLAG_DEFAULT; | |
622 | q->queue_lock = lock; | |
623 | ||
624 | /* | |
625 | * This also sets hw/phys segments, boundary and size | |
626 | */ | |
627 | blk_queue_make_request(q, __make_request); | |
628 | ||
629 | q->sg_reserved_size = INT_MAX; | |
630 | ||
631 | /* | |
632 | * all done | |
633 | */ | |
634 | if (!elevator_init(q, NULL)) { | |
635 | blk_queue_congestion_threshold(q); | |
636 | return q; | |
637 | } | |
638 | ||
639 | return NULL; | |
640 | } | |
641 | EXPORT_SYMBOL(blk_init_allocated_queue_node); | |
642 | ||
643 | int blk_get_queue(struct request_queue *q) | |
644 | { | |
645 | if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { | |
646 | kobject_get(&q->kobj); | |
647 | return 0; | |
648 | } | |
649 | ||
650 | return 1; | |
651 | } | |
652 | ||
653 | static inline void blk_free_request(struct request_queue *q, struct request *rq) | |
654 | { | |
655 | if (rq->cmd_flags & REQ_ELVPRIV) | |
656 | elv_put_request(q, rq); | |
657 | mempool_free(rq, q->rq.rq_pool); | |
658 | } | |
659 | ||
660 | static struct request * | |
661 | blk_alloc_request(struct request_queue *q, int flags, int priv, gfp_t gfp_mask) | |
662 | { | |
663 | struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); | |
664 | ||
665 | if (!rq) | |
666 | return NULL; | |
667 | ||
668 | blk_rq_init(q, rq); | |
669 | ||
670 | rq->cmd_flags = flags | REQ_ALLOCED; | |
671 | ||
672 | if (priv) { | |
673 | if (unlikely(elv_set_request(q, rq, gfp_mask))) { | |
674 | mempool_free(rq, q->rq.rq_pool); | |
675 | return NULL; | |
676 | } | |
677 | rq->cmd_flags |= REQ_ELVPRIV; | |
678 | } | |
679 | ||
680 | return rq; | |
681 | } | |
682 | ||
683 | /* | |
684 | * ioc_batching returns true if the ioc is a valid batching request and | |
685 | * should be given priority access to a request. | |
686 | */ | |
687 | static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) | |
688 | { | |
689 | if (!ioc) | |
690 | return 0; | |
691 | ||
692 | /* | |
693 | * Make sure the process is able to allocate at least 1 request | |
694 | * even if the batch times out, otherwise we could theoretically | |
695 | * lose wakeups. | |
696 | */ | |
697 | return ioc->nr_batch_requests == q->nr_batching || | |
698 | (ioc->nr_batch_requests > 0 | |
699 | && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); | |
700 | } | |
701 | ||
702 | /* | |
703 | * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This | |
704 | * will cause the process to be a "batcher" on all queues in the system. This | |
705 | * is the behaviour we want though - once it gets a wakeup it should be given | |
706 | * a nice run. | |
707 | */ | |
708 | static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) | |
709 | { | |
710 | if (!ioc || ioc_batching(q, ioc)) | |
711 | return; | |
712 | ||
713 | ioc->nr_batch_requests = q->nr_batching; | |
714 | ioc->last_waited = jiffies; | |
715 | } | |
716 | ||
717 | static void __freed_request(struct request_queue *q, int sync) | |
718 | { | |
719 | struct request_list *rl = &q->rq; | |
720 | ||
721 | if (rl->count[sync] < queue_congestion_off_threshold(q)) | |
722 | blk_clear_queue_congested(q, sync); | |
723 | ||
724 | if (rl->count[sync] + 1 <= q->nr_requests) { | |
725 | if (waitqueue_active(&rl->wait[sync])) | |
726 | wake_up(&rl->wait[sync]); | |
727 | ||
728 | blk_clear_queue_full(q, sync); | |
729 | } | |
730 | } | |
731 | ||
732 | /* | |
733 | * A request has just been released. Account for it, update the full and | |
734 | * congestion status, wake up any waiters. Called under q->queue_lock. | |
735 | */ | |
736 | static void freed_request(struct request_queue *q, int sync, int priv) | |
737 | { | |
738 | struct request_list *rl = &q->rq; | |
739 | ||
740 | rl->count[sync]--; | |
741 | if (priv) | |
742 | rl->elvpriv--; | |
743 | ||
744 | __freed_request(q, sync); | |
745 | ||
746 | if (unlikely(rl->starved[sync ^ 1])) | |
747 | __freed_request(q, sync ^ 1); | |
748 | } | |
749 | ||
750 | /* | |
751 | * Get a free request, queue_lock must be held. | |
752 | * Returns NULL on failure, with queue_lock held. | |
753 | * Returns !NULL on success, with queue_lock *not held*. | |
754 | */ | |
755 | static struct request *get_request(struct request_queue *q, int rw_flags, | |
756 | struct bio *bio, gfp_t gfp_mask) | |
757 | { | |
758 | struct request *rq = NULL; | |
759 | struct request_list *rl = &q->rq; | |
760 | struct io_context *ioc = NULL; | |
761 | const bool is_sync = rw_is_sync(rw_flags) != 0; | |
762 | int may_queue, priv; | |
763 | ||
764 | may_queue = elv_may_queue(q, rw_flags); | |
765 | if (may_queue == ELV_MQUEUE_NO) | |
766 | goto rq_starved; | |
767 | ||
768 | if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { | |
769 | if (rl->count[is_sync]+1 >= q->nr_requests) { | |
770 | ioc = current_io_context(GFP_ATOMIC, q->node); | |
771 | /* | |
772 | * The queue will fill after this allocation, so set | |
773 | * it as full, and mark this process as "batching". | |
774 | * This process will be allowed to complete a batch of | |
775 | * requests, others will be blocked. | |
776 | */ | |
777 | if (!blk_queue_full(q, is_sync)) { | |
778 | ioc_set_batching(q, ioc); | |
779 | blk_set_queue_full(q, is_sync); | |
780 | } else { | |
781 | if (may_queue != ELV_MQUEUE_MUST | |
782 | && !ioc_batching(q, ioc)) { | |
783 | /* | |
784 | * The queue is full and the allocating | |
785 | * process is not a "batcher", and not | |
786 | * exempted by the IO scheduler | |
787 | */ | |
788 | goto out; | |
789 | } | |
790 | } | |
791 | } | |
792 | blk_set_queue_congested(q, is_sync); | |
793 | } | |
794 | ||
795 | /* | |
796 | * Only allow batching queuers to allocate up to 50% over the defined | |
797 | * limit of requests, otherwise we could have thousands of requests | |
798 | * allocated with any setting of ->nr_requests | |
799 | */ | |
800 | if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) | |
801 | goto out; | |
802 | ||
803 | rl->count[is_sync]++; | |
804 | rl->starved[is_sync] = 0; | |
805 | ||
806 | priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); | |
807 | if (priv) | |
808 | rl->elvpriv++; | |
809 | ||
810 | if (blk_queue_io_stat(q)) | |
811 | rw_flags |= REQ_IO_STAT; | |
812 | spin_unlock_irq(q->queue_lock); | |
813 | ||
814 | rq = blk_alloc_request(q, rw_flags, priv, gfp_mask); | |
815 | if (unlikely(!rq)) { | |
816 | /* | |
817 | * Allocation failed presumably due to memory. Undo anything | |
818 | * we might have messed up. | |
819 | * | |
820 | * Allocating task should really be put onto the front of the | |
821 | * wait queue, but this is pretty rare. | |
822 | */ | |
823 | spin_lock_irq(q->queue_lock); | |
824 | freed_request(q, is_sync, priv); | |
825 | ||
826 | /* | |
827 | * in the very unlikely event that allocation failed and no | |
828 | * requests for this direction was pending, mark us starved | |
829 | * so that freeing of a request in the other direction will | |
830 | * notice us. another possible fix would be to split the | |
831 | * rq mempool into READ and WRITE | |
832 | */ | |
833 | rq_starved: | |
834 | if (unlikely(rl->count[is_sync] == 0)) | |
835 | rl->starved[is_sync] = 1; | |
836 | ||
837 | goto out; | |
838 | } | |
839 | ||
840 | /* | |
841 | * ioc may be NULL here, and ioc_batching will be false. That's | |
842 | * OK, if the queue is under the request limit then requests need | |
843 | * not count toward the nr_batch_requests limit. There will always | |
844 | * be some limit enforced by BLK_BATCH_TIME. | |
845 | */ | |
846 | if (ioc_batching(q, ioc)) | |
847 | ioc->nr_batch_requests--; | |
848 | ||
849 | trace_block_getrq(q, bio, rw_flags & 1); | |
850 | out: | |
851 | return rq; | |
852 | } | |
853 | ||
854 | /* | |
855 | * No available requests for this queue, unplug the device and wait for some | |
856 | * requests to become available. | |
857 | * | |
858 | * Called with q->queue_lock held, and returns with it unlocked. | |
859 | */ | |
860 | static struct request *get_request_wait(struct request_queue *q, int rw_flags, | |
861 | struct bio *bio) | |
862 | { | |
863 | const bool is_sync = rw_is_sync(rw_flags) != 0; | |
864 | struct request *rq; | |
865 | ||
866 | rq = get_request(q, rw_flags, bio, GFP_NOIO); | |
867 | while (!rq) { | |
868 | DEFINE_WAIT(wait); | |
869 | struct io_context *ioc; | |
870 | struct request_list *rl = &q->rq; | |
871 | ||
872 | prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, | |
873 | TASK_UNINTERRUPTIBLE); | |
874 | ||
875 | trace_block_sleeprq(q, bio, rw_flags & 1); | |
876 | ||
877 | __generic_unplug_device(q); | |
878 | spin_unlock_irq(q->queue_lock); | |
879 | io_schedule(); | |
880 | ||
881 | /* | |
882 | * After sleeping, we become a "batching" process and | |
883 | * will be able to allocate at least one request, and | |
884 | * up to a big batch of them for a small period time. | |
885 | * See ioc_batching, ioc_set_batching | |
886 | */ | |
887 | ioc = current_io_context(GFP_NOIO, q->node); | |
888 | ioc_set_batching(q, ioc); | |
889 | ||
890 | spin_lock_irq(q->queue_lock); | |
891 | finish_wait(&rl->wait[is_sync], &wait); | |
892 | ||
893 | rq = get_request(q, rw_flags, bio, GFP_NOIO); | |
894 | }; | |
895 | ||
896 | return rq; | |
897 | } | |
898 | ||
899 | struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) | |
900 | { | |
901 | struct request *rq; | |
902 | ||
903 | BUG_ON(rw != READ && rw != WRITE); | |
904 | ||
905 | spin_lock_irq(q->queue_lock); | |
906 | if (gfp_mask & __GFP_WAIT) { | |
907 | rq = get_request_wait(q, rw, NULL); | |
908 | } else { | |
909 | rq = get_request(q, rw, NULL, gfp_mask); | |
910 | if (!rq) | |
911 | spin_unlock_irq(q->queue_lock); | |
912 | } | |
913 | /* q->queue_lock is unlocked at this point */ | |
914 | ||
915 | return rq; | |
916 | } | |
917 | EXPORT_SYMBOL(blk_get_request); | |
918 | ||
919 | /** | |
920 | * blk_make_request - given a bio, allocate a corresponding struct request. | |
921 | * @q: target request queue | |
922 | * @bio: The bio describing the memory mappings that will be submitted for IO. | |
923 | * It may be a chained-bio properly constructed by block/bio layer. | |
924 | * @gfp_mask: gfp flags to be used for memory allocation | |
925 | * | |
926 | * blk_make_request is the parallel of generic_make_request for BLOCK_PC | |
927 | * type commands. Where the struct request needs to be farther initialized by | |
928 | * the caller. It is passed a &struct bio, which describes the memory info of | |
929 | * the I/O transfer. | |
930 | * | |
931 | * The caller of blk_make_request must make sure that bi_io_vec | |
932 | * are set to describe the memory buffers. That bio_data_dir() will return | |
933 | * the needed direction of the request. (And all bio's in the passed bio-chain | |
934 | * are properly set accordingly) | |
935 | * | |
936 | * If called under none-sleepable conditions, mapped bio buffers must not | |
937 | * need bouncing, by calling the appropriate masked or flagged allocator, | |
938 | * suitable for the target device. Otherwise the call to blk_queue_bounce will | |
939 | * BUG. | |
940 | * | |
941 | * WARNING: When allocating/cloning a bio-chain, careful consideration should be | |
942 | * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for | |
943 | * anything but the first bio in the chain. Otherwise you risk waiting for IO | |
944 | * completion of a bio that hasn't been submitted yet, thus resulting in a | |
945 | * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead | |
946 | * of bio_alloc(), as that avoids the mempool deadlock. | |
947 | * If possible a big IO should be split into smaller parts when allocation | |
948 | * fails. Partial allocation should not be an error, or you risk a live-lock. | |
949 | */ | |
950 | struct request *blk_make_request(struct request_queue *q, struct bio *bio, | |
951 | gfp_t gfp_mask) | |
952 | { | |
953 | struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask); | |
954 | ||
955 | if (unlikely(!rq)) | |
956 | return ERR_PTR(-ENOMEM); | |
957 | ||
958 | for_each_bio(bio) { | |
959 | struct bio *bounce_bio = bio; | |
960 | int ret; | |
961 | ||
962 | blk_queue_bounce(q, &bounce_bio); | |
963 | ret = blk_rq_append_bio(q, rq, bounce_bio); | |
964 | if (unlikely(ret)) { | |
965 | blk_put_request(rq); | |
966 | return ERR_PTR(ret); | |
967 | } | |
968 | } | |
969 | ||
970 | return rq; | |
971 | } | |
972 | EXPORT_SYMBOL(blk_make_request); | |
973 | ||
974 | /** | |
975 | * blk_requeue_request - put a request back on queue | |
976 | * @q: request queue where request should be inserted | |
977 | * @rq: request to be inserted | |
978 | * | |
979 | * Description: | |
980 | * Drivers often keep queueing requests until the hardware cannot accept | |
981 | * more, when that condition happens we need to put the request back | |
982 | * on the queue. Must be called with queue lock held. | |
983 | */ | |
984 | void blk_requeue_request(struct request_queue *q, struct request *rq) | |
985 | { | |
986 | blk_delete_timer(rq); | |
987 | blk_clear_rq_complete(rq); | |
988 | trace_block_rq_requeue(q, rq); | |
989 | ||
990 | if (blk_rq_tagged(rq)) | |
991 | blk_queue_end_tag(q, rq); | |
992 | ||
993 | BUG_ON(blk_queued_rq(rq)); | |
994 | ||
995 | elv_requeue_request(q, rq); | |
996 | } | |
997 | EXPORT_SYMBOL(blk_requeue_request); | |
998 | ||
999 | /** | |
1000 | * blk_insert_request - insert a special request into a request queue | |
1001 | * @q: request queue where request should be inserted | |
1002 | * @rq: request to be inserted | |
1003 | * @at_head: insert request at head or tail of queue | |
1004 | * @data: private data | |
1005 | * | |
1006 | * Description: | |
1007 | * Many block devices need to execute commands asynchronously, so they don't | |
1008 | * block the whole kernel from preemption during request execution. This is | |
1009 | * accomplished normally by inserting aritficial requests tagged as | |
1010 | * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them | |
1011 | * be scheduled for actual execution by the request queue. | |
1012 | * | |
1013 | * We have the option of inserting the head or the tail of the queue. | |
1014 | * Typically we use the tail for new ioctls and so forth. We use the head | |
1015 | * of the queue for things like a QUEUE_FULL message from a device, or a | |
1016 | * host that is unable to accept a particular command. | |
1017 | */ | |
1018 | void blk_insert_request(struct request_queue *q, struct request *rq, | |
1019 | int at_head, void *data) | |
1020 | { | |
1021 | int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; | |
1022 | unsigned long flags; | |
1023 | ||
1024 | /* | |
1025 | * tell I/O scheduler that this isn't a regular read/write (ie it | |
1026 | * must not attempt merges on this) and that it acts as a soft | |
1027 | * barrier | |
1028 | */ | |
1029 | rq->cmd_type = REQ_TYPE_SPECIAL; | |
1030 | ||
1031 | rq->special = data; | |
1032 | ||
1033 | spin_lock_irqsave(q->queue_lock, flags); | |
1034 | ||
1035 | /* | |
1036 | * If command is tagged, release the tag | |
1037 | */ | |
1038 | if (blk_rq_tagged(rq)) | |
1039 | blk_queue_end_tag(q, rq); | |
1040 | ||
1041 | drive_stat_acct(rq, 1); | |
1042 | __elv_add_request(q, rq, where, 0); | |
1043 | __blk_run_queue(q); | |
1044 | spin_unlock_irqrestore(q->queue_lock, flags); | |
1045 | } | |
1046 | EXPORT_SYMBOL(blk_insert_request); | |
1047 | ||
1048 | /* | |
1049 | * add-request adds a request to the linked list. | |
1050 | * queue lock is held and interrupts disabled, as we muck with the | |
1051 | * request queue list. | |
1052 | */ | |
1053 | static inline void add_request(struct request_queue *q, struct request *req) | |
1054 | { | |
1055 | drive_stat_acct(req, 1); | |
1056 | ||
1057 | /* | |
1058 | * elevator indicated where it wants this request to be | |
1059 | * inserted at elevator_merge time | |
1060 | */ | |
1061 | __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0); | |
1062 | } | |
1063 | ||
1064 | static void part_round_stats_single(int cpu, struct hd_struct *part, | |
1065 | unsigned long now) | |
1066 | { | |
1067 | if (now == part->stamp) | |
1068 | return; | |
1069 | ||
1070 | if (part_in_flight(part)) { | |
1071 | __part_stat_add(cpu, part, time_in_queue, | |
1072 | part_in_flight(part) * (now - part->stamp)); | |
1073 | __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); | |
1074 | } | |
1075 | part->stamp = now; | |
1076 | } | |
1077 | ||
1078 | /** | |
1079 | * part_round_stats() - Round off the performance stats on a struct disk_stats. | |
1080 | * @cpu: cpu number for stats access | |
1081 | * @part: target partition | |
1082 | * | |
1083 | * The average IO queue length and utilisation statistics are maintained | |
1084 | * by observing the current state of the queue length and the amount of | |
1085 | * time it has been in this state for. | |
1086 | * | |
1087 | * Normally, that accounting is done on IO completion, but that can result | |
1088 | * in more than a second's worth of IO being accounted for within any one | |
1089 | * second, leading to >100% utilisation. To deal with that, we call this | |
1090 | * function to do a round-off before returning the results when reading | |
1091 | * /proc/diskstats. This accounts immediately for all queue usage up to | |
1092 | * the current jiffies and restarts the counters again. | |
1093 | */ | |
1094 | void part_round_stats(int cpu, struct hd_struct *part) | |
1095 | { | |
1096 | unsigned long now = jiffies; | |
1097 | ||
1098 | if (part->partno) | |
1099 | part_round_stats_single(cpu, &part_to_disk(part)->part0, now); | |
1100 | part_round_stats_single(cpu, part, now); | |
1101 | } | |
1102 | EXPORT_SYMBOL_GPL(part_round_stats); | |
1103 | ||
1104 | /* | |
1105 | * queue lock must be held | |
1106 | */ | |
1107 | void __blk_put_request(struct request_queue *q, struct request *req) | |
1108 | { | |
1109 | if (unlikely(!q)) | |
1110 | return; | |
1111 | if (unlikely(--req->ref_count)) | |
1112 | return; | |
1113 | ||
1114 | elv_completed_request(q, req); | |
1115 | ||
1116 | /* this is a bio leak */ | |
1117 | WARN_ON(req->bio != NULL); | |
1118 | ||
1119 | /* | |
1120 | * Request may not have originated from ll_rw_blk. if not, | |
1121 | * it didn't come out of our reserved rq pools | |
1122 | */ | |
1123 | if (req->cmd_flags & REQ_ALLOCED) { | |
1124 | int is_sync = rq_is_sync(req) != 0; | |
1125 | int priv = req->cmd_flags & REQ_ELVPRIV; | |
1126 | ||
1127 | BUG_ON(!list_empty(&req->queuelist)); | |
1128 | BUG_ON(!hlist_unhashed(&req->hash)); | |
1129 | ||
1130 | blk_free_request(q, req); | |
1131 | freed_request(q, is_sync, priv); | |
1132 | } | |
1133 | } | |
1134 | EXPORT_SYMBOL_GPL(__blk_put_request); | |
1135 | ||
1136 | void blk_put_request(struct request *req) | |
1137 | { | |
1138 | unsigned long flags; | |
1139 | struct request_queue *q = req->q; | |
1140 | ||
1141 | spin_lock_irqsave(q->queue_lock, flags); | |
1142 | __blk_put_request(q, req); | |
1143 | spin_unlock_irqrestore(q->queue_lock, flags); | |
1144 | } | |
1145 | EXPORT_SYMBOL(blk_put_request); | |
1146 | ||
1147 | /** | |
1148 | * blk_add_request_payload - add a payload to a request | |
1149 | * @rq: request to update | |
1150 | * @page: page backing the payload | |
1151 | * @len: length of the payload. | |
1152 | * | |
1153 | * This allows to later add a payload to an already submitted request by | |
1154 | * a block driver. The driver needs to take care of freeing the payload | |
1155 | * itself. | |
1156 | * | |
1157 | * Note that this is a quite horrible hack and nothing but handling of | |
1158 | * discard requests should ever use it. | |
1159 | */ | |
1160 | void blk_add_request_payload(struct request *rq, struct page *page, | |
1161 | unsigned int len) | |
1162 | { | |
1163 | struct bio *bio = rq->bio; | |
1164 | ||
1165 | bio->bi_io_vec->bv_page = page; | |
1166 | bio->bi_io_vec->bv_offset = 0; | |
1167 | bio->bi_io_vec->bv_len = len; | |
1168 | ||
1169 | bio->bi_size = len; | |
1170 | bio->bi_vcnt = 1; | |
1171 | bio->bi_phys_segments = 1; | |
1172 | ||
1173 | rq->__data_len = rq->resid_len = len; | |
1174 | rq->nr_phys_segments = 1; | |
1175 | rq->buffer = bio_data(bio); | |
1176 | } | |
1177 | EXPORT_SYMBOL_GPL(blk_add_request_payload); | |
1178 | ||
1179 | void init_request_from_bio(struct request *req, struct bio *bio) | |
1180 | { | |
1181 | req->cpu = bio->bi_comp_cpu; | |
1182 | req->cmd_type = REQ_TYPE_FS; | |
1183 | ||
1184 | req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK; | |
1185 | if (bio->bi_rw & REQ_RAHEAD) | |
1186 | req->cmd_flags |= REQ_FAILFAST_MASK; | |
1187 | ||
1188 | req->errors = 0; | |
1189 | req->__sector = bio->bi_sector; | |
1190 | req->ioprio = bio_prio(bio); | |
1191 | blk_rq_bio_prep(req->q, req, bio); | |
1192 | } | |
1193 | ||
1194 | /* | |
1195 | * Only disabling plugging for non-rotational devices if it does tagging | |
1196 | * as well, otherwise we do need the proper merging | |
1197 | */ | |
1198 | static inline bool queue_should_plug(struct request_queue *q) | |
1199 | { | |
1200 | return !(blk_queue_nonrot(q) && blk_queue_tagged(q)); | |
1201 | } | |
1202 | ||
1203 | static int __make_request(struct request_queue *q, struct bio *bio) | |
1204 | { | |
1205 | struct request *req; | |
1206 | int el_ret; | |
1207 | unsigned int bytes = bio->bi_size; | |
1208 | const unsigned short prio = bio_prio(bio); | |
1209 | const bool sync = (bio->bi_rw & REQ_SYNC); | |
1210 | const bool unplug = (bio->bi_rw & REQ_UNPLUG); | |
1211 | const unsigned int ff = bio->bi_rw & REQ_FAILFAST_MASK; | |
1212 | int rw_flags; | |
1213 | ||
1214 | if ((bio->bi_rw & REQ_HARDBARRIER) && | |
1215 | (q->next_ordered == QUEUE_ORDERED_NONE)) { | |
1216 | bio_endio(bio, -EOPNOTSUPP); | |
1217 | return 0; | |
1218 | } | |
1219 | /* | |
1220 | * low level driver can indicate that it wants pages above a | |
1221 | * certain limit bounced to low memory (ie for highmem, or even | |
1222 | * ISA dma in theory) | |
1223 | */ | |
1224 | blk_queue_bounce(q, &bio); | |
1225 | ||
1226 | spin_lock_irq(q->queue_lock); | |
1227 | ||
1228 | if (unlikely((bio->bi_rw & REQ_HARDBARRIER)) || elv_queue_empty(q)) | |
1229 | goto get_rq; | |
1230 | ||
1231 | el_ret = elv_merge(q, &req, bio); | |
1232 | switch (el_ret) { | |
1233 | case ELEVATOR_BACK_MERGE: | |
1234 | BUG_ON(!rq_mergeable(req)); | |
1235 | ||
1236 | if (!ll_back_merge_fn(q, req, bio)) | |
1237 | break; | |
1238 | ||
1239 | trace_block_bio_backmerge(q, bio); | |
1240 | ||
1241 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) | |
1242 | blk_rq_set_mixed_merge(req); | |
1243 | ||
1244 | req->biotail->bi_next = bio; | |
1245 | req->biotail = bio; | |
1246 | req->__data_len += bytes; | |
1247 | req->ioprio = ioprio_best(req->ioprio, prio); | |
1248 | if (!blk_rq_cpu_valid(req)) | |
1249 | req->cpu = bio->bi_comp_cpu; | |
1250 | drive_stat_acct(req, 0); | |
1251 | elv_bio_merged(q, req, bio); | |
1252 | if (!attempt_back_merge(q, req)) | |
1253 | elv_merged_request(q, req, el_ret); | |
1254 | goto out; | |
1255 | ||
1256 | case ELEVATOR_FRONT_MERGE: | |
1257 | BUG_ON(!rq_mergeable(req)); | |
1258 | ||
1259 | if (!ll_front_merge_fn(q, req, bio)) | |
1260 | break; | |
1261 | ||
1262 | trace_block_bio_frontmerge(q, bio); | |
1263 | ||
1264 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) { | |
1265 | blk_rq_set_mixed_merge(req); | |
1266 | req->cmd_flags &= ~REQ_FAILFAST_MASK; | |
1267 | req->cmd_flags |= ff; | |
1268 | } | |
1269 | ||
1270 | bio->bi_next = req->bio; | |
1271 | req->bio = bio; | |
1272 | ||
1273 | /* | |
1274 | * may not be valid. if the low level driver said | |
1275 | * it didn't need a bounce buffer then it better | |
1276 | * not touch req->buffer either... | |
1277 | */ | |
1278 | req->buffer = bio_data(bio); | |
1279 | req->__sector = bio->bi_sector; | |
1280 | req->__data_len += bytes; | |
1281 | req->ioprio = ioprio_best(req->ioprio, prio); | |
1282 | if (!blk_rq_cpu_valid(req)) | |
1283 | req->cpu = bio->bi_comp_cpu; | |
1284 | drive_stat_acct(req, 0); | |
1285 | elv_bio_merged(q, req, bio); | |
1286 | if (!attempt_front_merge(q, req)) | |
1287 | elv_merged_request(q, req, el_ret); | |
1288 | goto out; | |
1289 | ||
1290 | /* ELV_NO_MERGE: elevator says don't/can't merge. */ | |
1291 | default: | |
1292 | ; | |
1293 | } | |
1294 | ||
1295 | get_rq: | |
1296 | /* | |
1297 | * This sync check and mask will be re-done in init_request_from_bio(), | |
1298 | * but we need to set it earlier to expose the sync flag to the | |
1299 | * rq allocator and io schedulers. | |
1300 | */ | |
1301 | rw_flags = bio_data_dir(bio); | |
1302 | if (sync) | |
1303 | rw_flags |= REQ_SYNC; | |
1304 | ||
1305 | /* | |
1306 | * Grab a free request. This is might sleep but can not fail. | |
1307 | * Returns with the queue unlocked. | |
1308 | */ | |
1309 | req = get_request_wait(q, rw_flags, bio); | |
1310 | ||
1311 | /* | |
1312 | * After dropping the lock and possibly sleeping here, our request | |
1313 | * may now be mergeable after it had proven unmergeable (above). | |
1314 | * We don't worry about that case for efficiency. It won't happen | |
1315 | * often, and the elevators are able to handle it. | |
1316 | */ | |
1317 | init_request_from_bio(req, bio); | |
1318 | ||
1319 | spin_lock_irq(q->queue_lock); | |
1320 | if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) || | |
1321 | bio_flagged(bio, BIO_CPU_AFFINE)) | |
1322 | req->cpu = blk_cpu_to_group(smp_processor_id()); | |
1323 | if (queue_should_plug(q) && elv_queue_empty(q)) | |
1324 | blk_plug_device(q); | |
1325 | add_request(q, req); | |
1326 | out: | |
1327 | if (unplug || !queue_should_plug(q)) | |
1328 | __generic_unplug_device(q); | |
1329 | spin_unlock_irq(q->queue_lock); | |
1330 | return 0; | |
1331 | } | |
1332 | ||
1333 | /* | |
1334 | * If bio->bi_dev is a partition, remap the location | |
1335 | */ | |
1336 | static inline void blk_partition_remap(struct bio *bio) | |
1337 | { | |
1338 | struct block_device *bdev = bio->bi_bdev; | |
1339 | ||
1340 | if (bio_sectors(bio) && bdev != bdev->bd_contains) { | |
1341 | struct hd_struct *p = bdev->bd_part; | |
1342 | ||
1343 | bio->bi_sector += p->start_sect; | |
1344 | bio->bi_bdev = bdev->bd_contains; | |
1345 | ||
1346 | trace_block_remap(bdev_get_queue(bio->bi_bdev), bio, | |
1347 | bdev->bd_dev, | |
1348 | bio->bi_sector - p->start_sect); | |
1349 | } | |
1350 | } | |
1351 | ||
1352 | static void handle_bad_sector(struct bio *bio) | |
1353 | { | |
1354 | char b[BDEVNAME_SIZE]; | |
1355 | ||
1356 | printk(KERN_INFO "attempt to access beyond end of device\n"); | |
1357 | printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", | |
1358 | bdevname(bio->bi_bdev, b), | |
1359 | bio->bi_rw, | |
1360 | (unsigned long long)bio->bi_sector + bio_sectors(bio), | |
1361 | (long long)(bio->bi_bdev->bd_inode->i_size >> 9)); | |
1362 | ||
1363 | set_bit(BIO_EOF, &bio->bi_flags); | |
1364 | } | |
1365 | ||
1366 | #ifdef CONFIG_FAIL_MAKE_REQUEST | |
1367 | ||
1368 | static DECLARE_FAULT_ATTR(fail_make_request); | |
1369 | ||
1370 | static int __init setup_fail_make_request(char *str) | |
1371 | { | |
1372 | return setup_fault_attr(&fail_make_request, str); | |
1373 | } | |
1374 | __setup("fail_make_request=", setup_fail_make_request); | |
1375 | ||
1376 | static int should_fail_request(struct bio *bio) | |
1377 | { | |
1378 | struct hd_struct *part = bio->bi_bdev->bd_part; | |
1379 | ||
1380 | if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail) | |
1381 | return should_fail(&fail_make_request, bio->bi_size); | |
1382 | ||
1383 | return 0; | |
1384 | } | |
1385 | ||
1386 | static int __init fail_make_request_debugfs(void) | |
1387 | { | |
1388 | return init_fault_attr_dentries(&fail_make_request, | |
1389 | "fail_make_request"); | |
1390 | } | |
1391 | ||
1392 | late_initcall(fail_make_request_debugfs); | |
1393 | ||
1394 | #else /* CONFIG_FAIL_MAKE_REQUEST */ | |
1395 | ||
1396 | static inline int should_fail_request(struct bio *bio) | |
1397 | { | |
1398 | return 0; | |
1399 | } | |
1400 | ||
1401 | #endif /* CONFIG_FAIL_MAKE_REQUEST */ | |
1402 | ||
1403 | /* | |
1404 | * Check whether this bio extends beyond the end of the device. | |
1405 | */ | |
1406 | static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) | |
1407 | { | |
1408 | sector_t maxsector; | |
1409 | ||
1410 | if (!nr_sectors) | |
1411 | return 0; | |
1412 | ||
1413 | /* Test device or partition size, when known. */ | |
1414 | maxsector = bio->bi_bdev->bd_inode->i_size >> 9; | |
1415 | if (maxsector) { | |
1416 | sector_t sector = bio->bi_sector; | |
1417 | ||
1418 | if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { | |
1419 | /* | |
1420 | * This may well happen - the kernel calls bread() | |
1421 | * without checking the size of the device, e.g., when | |
1422 | * mounting a device. | |
1423 | */ | |
1424 | handle_bad_sector(bio); | |
1425 | return 1; | |
1426 | } | |
1427 | } | |
1428 | ||
1429 | return 0; | |
1430 | } | |
1431 | ||
1432 | /** | |
1433 | * generic_make_request - hand a buffer to its device driver for I/O | |
1434 | * @bio: The bio describing the location in memory and on the device. | |
1435 | * | |
1436 | * generic_make_request() is used to make I/O requests of block | |
1437 | * devices. It is passed a &struct bio, which describes the I/O that needs | |
1438 | * to be done. | |
1439 | * | |
1440 | * generic_make_request() does not return any status. The | |
1441 | * success/failure status of the request, along with notification of | |
1442 | * completion, is delivered asynchronously through the bio->bi_end_io | |
1443 | * function described (one day) else where. | |
1444 | * | |
1445 | * The caller of generic_make_request must make sure that bi_io_vec | |
1446 | * are set to describe the memory buffer, and that bi_dev and bi_sector are | |
1447 | * set to describe the device address, and the | |
1448 | * bi_end_io and optionally bi_private are set to describe how | |
1449 | * completion notification should be signaled. | |
1450 | * | |
1451 | * generic_make_request and the drivers it calls may use bi_next if this | |
1452 | * bio happens to be merged with someone else, and may change bi_dev and | |
1453 | * bi_sector for remaps as it sees fit. So the values of these fields | |
1454 | * should NOT be depended on after the call to generic_make_request. | |
1455 | */ | |
1456 | static inline void __generic_make_request(struct bio *bio) | |
1457 | { | |
1458 | struct request_queue *q; | |
1459 | sector_t old_sector; | |
1460 | int ret, nr_sectors = bio_sectors(bio); | |
1461 | dev_t old_dev; | |
1462 | int err = -EIO; | |
1463 | ||
1464 | might_sleep(); | |
1465 | ||
1466 | if (bio_check_eod(bio, nr_sectors)) | |
1467 | goto end_io; | |
1468 | ||
1469 | /* | |
1470 | * Resolve the mapping until finished. (drivers are | |
1471 | * still free to implement/resolve their own stacking | |
1472 | * by explicitly returning 0) | |
1473 | * | |
1474 | * NOTE: we don't repeat the blk_size check for each new device. | |
1475 | * Stacking drivers are expected to know what they are doing. | |
1476 | */ | |
1477 | old_sector = -1; | |
1478 | old_dev = 0; | |
1479 | do { | |
1480 | char b[BDEVNAME_SIZE]; | |
1481 | ||
1482 | q = bdev_get_queue(bio->bi_bdev); | |
1483 | if (unlikely(!q)) { | |
1484 | printk(KERN_ERR | |
1485 | "generic_make_request: Trying to access " | |
1486 | "nonexistent block-device %s (%Lu)\n", | |
1487 | bdevname(bio->bi_bdev, b), | |
1488 | (long long) bio->bi_sector); | |
1489 | goto end_io; | |
1490 | } | |
1491 | ||
1492 | if (unlikely(!(bio->bi_rw & REQ_DISCARD) && | |
1493 | nr_sectors > queue_max_hw_sectors(q))) { | |
1494 | printk(KERN_ERR "bio too big device %s (%u > %u)\n", | |
1495 | bdevname(bio->bi_bdev, b), | |
1496 | bio_sectors(bio), | |
1497 | queue_max_hw_sectors(q)); | |
1498 | goto end_io; | |
1499 | } | |
1500 | ||
1501 | if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) | |
1502 | goto end_io; | |
1503 | ||
1504 | if (should_fail_request(bio)) | |
1505 | goto end_io; | |
1506 | ||
1507 | /* | |
1508 | * If this device has partitions, remap block n | |
1509 | * of partition p to block n+start(p) of the disk. | |
1510 | */ | |
1511 | blk_partition_remap(bio); | |
1512 | ||
1513 | if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) | |
1514 | goto end_io; | |
1515 | ||
1516 | if (old_sector != -1) | |
1517 | trace_block_remap(q, bio, old_dev, old_sector); | |
1518 | ||
1519 | old_sector = bio->bi_sector; | |
1520 | old_dev = bio->bi_bdev->bd_dev; | |
1521 | ||
1522 | if (bio_check_eod(bio, nr_sectors)) | |
1523 | goto end_io; | |
1524 | ||
1525 | if ((bio->bi_rw & REQ_DISCARD) && | |
1526 | (!blk_queue_discard(q) || | |
1527 | ((bio->bi_rw & REQ_SECURE) && | |
1528 | !blk_queue_secdiscard(q)))) { | |
1529 | err = -EOPNOTSUPP; | |
1530 | goto end_io; | |
1531 | } | |
1532 | ||
1533 | blk_throtl_bio(q, &bio); | |
1534 | ||
1535 | /* | |
1536 | * If bio = NULL, bio has been throttled and will be submitted | |
1537 | * later. | |
1538 | */ | |
1539 | if (!bio) | |
1540 | break; | |
1541 | ||
1542 | trace_block_bio_queue(q, bio); | |
1543 | ||
1544 | ret = q->make_request_fn(q, bio); | |
1545 | } while (ret); | |
1546 | ||
1547 | return; | |
1548 | ||
1549 | end_io: | |
1550 | bio_endio(bio, err); | |
1551 | } | |
1552 | ||
1553 | /* | |
1554 | * We only want one ->make_request_fn to be active at a time, | |
1555 | * else stack usage with stacked devices could be a problem. | |
1556 | * So use current->bio_list to keep a list of requests | |
1557 | * submited by a make_request_fn function. | |
1558 | * current->bio_list is also used as a flag to say if | |
1559 | * generic_make_request is currently active in this task or not. | |
1560 | * If it is NULL, then no make_request is active. If it is non-NULL, | |
1561 | * then a make_request is active, and new requests should be added | |
1562 | * at the tail | |
1563 | */ | |
1564 | void generic_make_request(struct bio *bio) | |
1565 | { | |
1566 | struct bio_list bio_list_on_stack; | |
1567 | ||
1568 | if (current->bio_list) { | |
1569 | /* make_request is active */ | |
1570 | bio_list_add(current->bio_list, bio); | |
1571 | return; | |
1572 | } | |
1573 | /* following loop may be a bit non-obvious, and so deserves some | |
1574 | * explanation. | |
1575 | * Before entering the loop, bio->bi_next is NULL (as all callers | |
1576 | * ensure that) so we have a list with a single bio. | |
1577 | * We pretend that we have just taken it off a longer list, so | |
1578 | * we assign bio_list to a pointer to the bio_list_on_stack, | |
1579 | * thus initialising the bio_list of new bios to be | |
1580 | * added. __generic_make_request may indeed add some more bios | |
1581 | * through a recursive call to generic_make_request. If it | |
1582 | * did, we find a non-NULL value in bio_list and re-enter the loop | |
1583 | * from the top. In this case we really did just take the bio | |
1584 | * of the top of the list (no pretending) and so remove it from | |
1585 | * bio_list, and call into __generic_make_request again. | |
1586 | * | |
1587 | * The loop was structured like this to make only one call to | |
1588 | * __generic_make_request (which is important as it is large and | |
1589 | * inlined) and to keep the structure simple. | |
1590 | */ | |
1591 | BUG_ON(bio->bi_next); | |
1592 | bio_list_init(&bio_list_on_stack); | |
1593 | current->bio_list = &bio_list_on_stack; | |
1594 | do { | |
1595 | __generic_make_request(bio); | |
1596 | bio = bio_list_pop(current->bio_list); | |
1597 | } while (bio); | |
1598 | current->bio_list = NULL; /* deactivate */ | |
1599 | } | |
1600 | EXPORT_SYMBOL(generic_make_request); | |
1601 | ||
1602 | /** | |
1603 | * submit_bio - submit a bio to the block device layer for I/O | |
1604 | * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) | |
1605 | * @bio: The &struct bio which describes the I/O | |
1606 | * | |
1607 | * submit_bio() is very similar in purpose to generic_make_request(), and | |
1608 | * uses that function to do most of the work. Both are fairly rough | |
1609 | * interfaces; @bio must be presetup and ready for I/O. | |
1610 | * | |
1611 | */ | |
1612 | void submit_bio(int rw, struct bio *bio) | |
1613 | { | |
1614 | int count = bio_sectors(bio); | |
1615 | ||
1616 | bio->bi_rw |= rw; | |
1617 | ||
1618 | /* | |
1619 | * If it's a regular read/write or a barrier with data attached, | |
1620 | * go through the normal accounting stuff before submission. | |
1621 | */ | |
1622 | if (bio_has_data(bio) && !(rw & REQ_DISCARD)) { | |
1623 | if (rw & WRITE) { | |
1624 | count_vm_events(PGPGOUT, count); | |
1625 | } else { | |
1626 | task_io_account_read(bio->bi_size); | |
1627 | count_vm_events(PGPGIN, count); | |
1628 | } | |
1629 | ||
1630 | if (unlikely(block_dump)) { | |
1631 | char b[BDEVNAME_SIZE]; | |
1632 | printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", | |
1633 | current->comm, task_pid_nr(current), | |
1634 | (rw & WRITE) ? "WRITE" : "READ", | |
1635 | (unsigned long long)bio->bi_sector, | |
1636 | bdevname(bio->bi_bdev, b), | |
1637 | count); | |
1638 | } | |
1639 | } | |
1640 | ||
1641 | generic_make_request(bio); | |
1642 | } | |
1643 | EXPORT_SYMBOL(submit_bio); | |
1644 | ||
1645 | /** | |
1646 | * blk_rq_check_limits - Helper function to check a request for the queue limit | |
1647 | * @q: the queue | |
1648 | * @rq: the request being checked | |
1649 | * | |
1650 | * Description: | |
1651 | * @rq may have been made based on weaker limitations of upper-level queues | |
1652 | * in request stacking drivers, and it may violate the limitation of @q. | |
1653 | * Since the block layer and the underlying device driver trust @rq | |
1654 | * after it is inserted to @q, it should be checked against @q before | |
1655 | * the insertion using this generic function. | |
1656 | * | |
1657 | * This function should also be useful for request stacking drivers | |
1658 | * in some cases below, so export this fuction. | |
1659 | * Request stacking drivers like request-based dm may change the queue | |
1660 | * limits while requests are in the queue (e.g. dm's table swapping). | |
1661 | * Such request stacking drivers should check those requests agaist | |
1662 | * the new queue limits again when they dispatch those requests, | |
1663 | * although such checkings are also done against the old queue limits | |
1664 | * when submitting requests. | |
1665 | */ | |
1666 | int blk_rq_check_limits(struct request_queue *q, struct request *rq) | |
1667 | { | |
1668 | if (rq->cmd_flags & REQ_DISCARD) | |
1669 | return 0; | |
1670 | ||
1671 | if (blk_rq_sectors(rq) > queue_max_sectors(q) || | |
1672 | blk_rq_bytes(rq) > queue_max_hw_sectors(q) << 9) { | |
1673 | printk(KERN_ERR "%s: over max size limit.\n", __func__); | |
1674 | return -EIO; | |
1675 | } | |
1676 | ||
1677 | /* | |
1678 | * queue's settings related to segment counting like q->bounce_pfn | |
1679 | * may differ from that of other stacking queues. | |
1680 | * Recalculate it to check the request correctly on this queue's | |
1681 | * limitation. | |
1682 | */ | |
1683 | blk_recalc_rq_segments(rq); | |
1684 | if (rq->nr_phys_segments > queue_max_segments(q)) { | |
1685 | printk(KERN_ERR "%s: over max segments limit.\n", __func__); | |
1686 | return -EIO; | |
1687 | } | |
1688 | ||
1689 | return 0; | |
1690 | } | |
1691 | EXPORT_SYMBOL_GPL(blk_rq_check_limits); | |
1692 | ||
1693 | /** | |
1694 | * blk_insert_cloned_request - Helper for stacking drivers to submit a request | |
1695 | * @q: the queue to submit the request | |
1696 | * @rq: the request being queued | |
1697 | */ | |
1698 | int blk_insert_cloned_request(struct request_queue *q, struct request *rq) | |
1699 | { | |
1700 | unsigned long flags; | |
1701 | ||
1702 | if (blk_rq_check_limits(q, rq)) | |
1703 | return -EIO; | |
1704 | ||
1705 | #ifdef CONFIG_FAIL_MAKE_REQUEST | |
1706 | if (rq->rq_disk && rq->rq_disk->part0.make_it_fail && | |
1707 | should_fail(&fail_make_request, blk_rq_bytes(rq))) | |
1708 | return -EIO; | |
1709 | #endif | |
1710 | ||
1711 | spin_lock_irqsave(q->queue_lock, flags); | |
1712 | ||
1713 | /* | |
1714 | * Submitting request must be dequeued before calling this function | |
1715 | * because it will be linked to another request_queue | |
1716 | */ | |
1717 | BUG_ON(blk_queued_rq(rq)); | |
1718 | ||
1719 | drive_stat_acct(rq, 1); | |
1720 | __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); | |
1721 | ||
1722 | spin_unlock_irqrestore(q->queue_lock, flags); | |
1723 | ||
1724 | return 0; | |
1725 | } | |
1726 | EXPORT_SYMBOL_GPL(blk_insert_cloned_request); | |
1727 | ||
1728 | /** | |
1729 | * blk_rq_err_bytes - determine number of bytes till the next failure boundary | |
1730 | * @rq: request to examine | |
1731 | * | |
1732 | * Description: | |
1733 | * A request could be merge of IOs which require different failure | |
1734 | * handling. This function determines the number of bytes which | |
1735 | * can be failed from the beginning of the request without | |
1736 | * crossing into area which need to be retried further. | |
1737 | * | |
1738 | * Return: | |
1739 | * The number of bytes to fail. | |
1740 | * | |
1741 | * Context: | |
1742 | * queue_lock must be held. | |
1743 | */ | |
1744 | unsigned int blk_rq_err_bytes(const struct request *rq) | |
1745 | { | |
1746 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
1747 | unsigned int bytes = 0; | |
1748 | struct bio *bio; | |
1749 | ||
1750 | if (!(rq->cmd_flags & REQ_MIXED_MERGE)) | |
1751 | return blk_rq_bytes(rq); | |
1752 | ||
1753 | /* | |
1754 | * Currently the only 'mixing' which can happen is between | |
1755 | * different fastfail types. We can safely fail portions | |
1756 | * which have all the failfast bits that the first one has - | |
1757 | * the ones which are at least as eager to fail as the first | |
1758 | * one. | |
1759 | */ | |
1760 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
1761 | if ((bio->bi_rw & ff) != ff) | |
1762 | break; | |
1763 | bytes += bio->bi_size; | |
1764 | } | |
1765 | ||
1766 | /* this could lead to infinite loop */ | |
1767 | BUG_ON(blk_rq_bytes(rq) && !bytes); | |
1768 | return bytes; | |
1769 | } | |
1770 | EXPORT_SYMBOL_GPL(blk_rq_err_bytes); | |
1771 | ||
1772 | static void blk_account_io_completion(struct request *req, unsigned int bytes) | |
1773 | { | |
1774 | if (blk_do_io_stat(req)) { | |
1775 | const int rw = rq_data_dir(req); | |
1776 | struct hd_struct *part; | |
1777 | int cpu; | |
1778 | ||
1779 | cpu = part_stat_lock(); | |
1780 | part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req)); | |
1781 | part_stat_add(cpu, part, sectors[rw], bytes >> 9); | |
1782 | part_stat_unlock(); | |
1783 | } | |
1784 | } | |
1785 | ||
1786 | static void blk_account_io_done(struct request *req) | |
1787 | { | |
1788 | /* | |
1789 | * Account IO completion. bar_rq isn't accounted as a normal | |
1790 | * IO on queueing nor completion. Accounting the containing | |
1791 | * request is enough. | |
1792 | */ | |
1793 | if (blk_do_io_stat(req) && req != &req->q->bar_rq) { | |
1794 | unsigned long duration = jiffies - req->start_time; | |
1795 | const int rw = rq_data_dir(req); | |
1796 | struct hd_struct *part; | |
1797 | int cpu; | |
1798 | ||
1799 | cpu = part_stat_lock(); | |
1800 | part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req)); | |
1801 | ||
1802 | part_stat_inc(cpu, part, ios[rw]); | |
1803 | part_stat_add(cpu, part, ticks[rw], duration); | |
1804 | part_round_stats(cpu, part); | |
1805 | part_dec_in_flight(part, rw); | |
1806 | ||
1807 | part_stat_unlock(); | |
1808 | } | |
1809 | } | |
1810 | ||
1811 | /** | |
1812 | * blk_peek_request - peek at the top of a request queue | |
1813 | * @q: request queue to peek at | |
1814 | * | |
1815 | * Description: | |
1816 | * Return the request at the top of @q. The returned request | |
1817 | * should be started using blk_start_request() before LLD starts | |
1818 | * processing it. | |
1819 | * | |
1820 | * Return: | |
1821 | * Pointer to the request at the top of @q if available. Null | |
1822 | * otherwise. | |
1823 | * | |
1824 | * Context: | |
1825 | * queue_lock must be held. | |
1826 | */ | |
1827 | struct request *blk_peek_request(struct request_queue *q) | |
1828 | { | |
1829 | struct request *rq; | |
1830 | int ret; | |
1831 | ||
1832 | while ((rq = __elv_next_request(q)) != NULL) { | |
1833 | if (!(rq->cmd_flags & REQ_STARTED)) { | |
1834 | /* | |
1835 | * This is the first time the device driver | |
1836 | * sees this request (possibly after | |
1837 | * requeueing). Notify IO scheduler. | |
1838 | */ | |
1839 | if (rq->cmd_flags & REQ_SORTED) | |
1840 | elv_activate_rq(q, rq); | |
1841 | ||
1842 | /* | |
1843 | * just mark as started even if we don't start | |
1844 | * it, a request that has been delayed should | |
1845 | * not be passed by new incoming requests | |
1846 | */ | |
1847 | rq->cmd_flags |= REQ_STARTED; | |
1848 | trace_block_rq_issue(q, rq); | |
1849 | } | |
1850 | ||
1851 | if (!q->boundary_rq || q->boundary_rq == rq) { | |
1852 | q->end_sector = rq_end_sector(rq); | |
1853 | q->boundary_rq = NULL; | |
1854 | } | |
1855 | ||
1856 | if (rq->cmd_flags & REQ_DONTPREP) | |
1857 | break; | |
1858 | ||
1859 | if (q->dma_drain_size && blk_rq_bytes(rq)) { | |
1860 | /* | |
1861 | * make sure space for the drain appears we | |
1862 | * know we can do this because max_hw_segments | |
1863 | * has been adjusted to be one fewer than the | |
1864 | * device can handle | |
1865 | */ | |
1866 | rq->nr_phys_segments++; | |
1867 | } | |
1868 | ||
1869 | if (!q->prep_rq_fn) | |
1870 | break; | |
1871 | ||
1872 | ret = q->prep_rq_fn(q, rq); | |
1873 | if (ret == BLKPREP_OK) { | |
1874 | break; | |
1875 | } else if (ret == BLKPREP_DEFER) { | |
1876 | /* | |
1877 | * the request may have been (partially) prepped. | |
1878 | * we need to keep this request in the front to | |
1879 | * avoid resource deadlock. REQ_STARTED will | |
1880 | * prevent other fs requests from passing this one. | |
1881 | */ | |
1882 | if (q->dma_drain_size && blk_rq_bytes(rq) && | |
1883 | !(rq->cmd_flags & REQ_DONTPREP)) { | |
1884 | /* | |
1885 | * remove the space for the drain we added | |
1886 | * so that we don't add it again | |
1887 | */ | |
1888 | --rq->nr_phys_segments; | |
1889 | } | |
1890 | ||
1891 | rq = NULL; | |
1892 | break; | |
1893 | } else if (ret == BLKPREP_KILL) { | |
1894 | rq->cmd_flags |= REQ_QUIET; | |
1895 | /* | |
1896 | * Mark this request as started so we don't trigger | |
1897 | * any debug logic in the end I/O path. | |
1898 | */ | |
1899 | blk_start_request(rq); | |
1900 | __blk_end_request_all(rq, -EIO); | |
1901 | } else { | |
1902 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); | |
1903 | break; | |
1904 | } | |
1905 | } | |
1906 | ||
1907 | return rq; | |
1908 | } | |
1909 | EXPORT_SYMBOL(blk_peek_request); | |
1910 | ||
1911 | void blk_dequeue_request(struct request *rq) | |
1912 | { | |
1913 | struct request_queue *q = rq->q; | |
1914 | ||
1915 | BUG_ON(list_empty(&rq->queuelist)); | |
1916 | BUG_ON(ELV_ON_HASH(rq)); | |
1917 | ||
1918 | list_del_init(&rq->queuelist); | |
1919 | ||
1920 | /* | |
1921 | * the time frame between a request being removed from the lists | |
1922 | * and to it is freed is accounted as io that is in progress at | |
1923 | * the driver side. | |
1924 | */ | |
1925 | if (blk_account_rq(rq)) { | |
1926 | q->in_flight[rq_is_sync(rq)]++; | |
1927 | set_io_start_time_ns(rq); | |
1928 | } | |
1929 | } | |
1930 | ||
1931 | /** | |
1932 | * blk_start_request - start request processing on the driver | |
1933 | * @req: request to dequeue | |
1934 | * | |
1935 | * Description: | |
1936 | * Dequeue @req and start timeout timer on it. This hands off the | |
1937 | * request to the driver. | |
1938 | * | |
1939 | * Block internal functions which don't want to start timer should | |
1940 | * call blk_dequeue_request(). | |
1941 | * | |
1942 | * Context: | |
1943 | * queue_lock must be held. | |
1944 | */ | |
1945 | void blk_start_request(struct request *req) | |
1946 | { | |
1947 | blk_dequeue_request(req); | |
1948 | ||
1949 | /* | |
1950 | * We are now handing the request to the hardware, initialize | |
1951 | * resid_len to full count and add the timeout handler. | |
1952 | */ | |
1953 | req->resid_len = blk_rq_bytes(req); | |
1954 | if (unlikely(blk_bidi_rq(req))) | |
1955 | req->next_rq->resid_len = blk_rq_bytes(req->next_rq); | |
1956 | ||
1957 | blk_add_timer(req); | |
1958 | } | |
1959 | EXPORT_SYMBOL(blk_start_request); | |
1960 | ||
1961 | /** | |
1962 | * blk_fetch_request - fetch a request from a request queue | |
1963 | * @q: request queue to fetch a request from | |
1964 | * | |
1965 | * Description: | |
1966 | * Return the request at the top of @q. The request is started on | |
1967 | * return and LLD can start processing it immediately. | |
1968 | * | |
1969 | * Return: | |
1970 | * Pointer to the request at the top of @q if available. Null | |
1971 | * otherwise. | |
1972 | * | |
1973 | * Context: | |
1974 | * queue_lock must be held. | |
1975 | */ | |
1976 | struct request *blk_fetch_request(struct request_queue *q) | |
1977 | { | |
1978 | struct request *rq; | |
1979 | ||
1980 | rq = blk_peek_request(q); | |
1981 | if (rq) | |
1982 | blk_start_request(rq); | |
1983 | return rq; | |
1984 | } | |
1985 | EXPORT_SYMBOL(blk_fetch_request); | |
1986 | ||
1987 | /** | |
1988 | * blk_update_request - Special helper function for request stacking drivers | |
1989 | * @req: the request being processed | |
1990 | * @error: %0 for success, < %0 for error | |
1991 | * @nr_bytes: number of bytes to complete @req | |
1992 | * | |
1993 | * Description: | |
1994 | * Ends I/O on a number of bytes attached to @req, but doesn't complete | |
1995 | * the request structure even if @req doesn't have leftover. | |
1996 | * If @req has leftover, sets it up for the next range of segments. | |
1997 | * | |
1998 | * This special helper function is only for request stacking drivers | |
1999 | * (e.g. request-based dm) so that they can handle partial completion. | |
2000 | * Actual device drivers should use blk_end_request instead. | |
2001 | * | |
2002 | * Passing the result of blk_rq_bytes() as @nr_bytes guarantees | |
2003 | * %false return from this function. | |
2004 | * | |
2005 | * Return: | |
2006 | * %false - this request doesn't have any more data | |
2007 | * %true - this request has more data | |
2008 | **/ | |
2009 | bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) | |
2010 | { | |
2011 | int total_bytes, bio_nbytes, next_idx = 0; | |
2012 | struct bio *bio; | |
2013 | ||
2014 | if (!req->bio) | |
2015 | return false; | |
2016 | ||
2017 | trace_block_rq_complete(req->q, req); | |
2018 | ||
2019 | /* | |
2020 | * For fs requests, rq is just carrier of independent bio's | |
2021 | * and each partial completion should be handled separately. | |
2022 | * Reset per-request error on each partial completion. | |
2023 | * | |
2024 | * TODO: tj: This is too subtle. It would be better to let | |
2025 | * low level drivers do what they see fit. | |
2026 | */ | |
2027 | if (req->cmd_type == REQ_TYPE_FS) | |
2028 | req->errors = 0; | |
2029 | ||
2030 | if (error && req->cmd_type == REQ_TYPE_FS && | |
2031 | !(req->cmd_flags & REQ_QUIET)) { | |
2032 | printk(KERN_ERR "end_request: I/O error, dev %s, sector %llu\n", | |
2033 | req->rq_disk ? req->rq_disk->disk_name : "?", | |
2034 | (unsigned long long)blk_rq_pos(req)); | |
2035 | } | |
2036 | ||
2037 | blk_account_io_completion(req, nr_bytes); | |
2038 | ||
2039 | total_bytes = bio_nbytes = 0; | |
2040 | while ((bio = req->bio) != NULL) { | |
2041 | int nbytes; | |
2042 | ||
2043 | if (nr_bytes >= bio->bi_size) { | |
2044 | req->bio = bio->bi_next; | |
2045 | nbytes = bio->bi_size; | |
2046 | req_bio_endio(req, bio, nbytes, error); | |
2047 | next_idx = 0; | |
2048 | bio_nbytes = 0; | |
2049 | } else { | |
2050 | int idx = bio->bi_idx + next_idx; | |
2051 | ||
2052 | if (unlikely(idx >= bio->bi_vcnt)) { | |
2053 | blk_dump_rq_flags(req, "__end_that"); | |
2054 | printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n", | |
2055 | __func__, idx, bio->bi_vcnt); | |
2056 | break; | |
2057 | } | |
2058 | ||
2059 | nbytes = bio_iovec_idx(bio, idx)->bv_len; | |
2060 | BIO_BUG_ON(nbytes > bio->bi_size); | |
2061 | ||
2062 | /* | |
2063 | * not a complete bvec done | |
2064 | */ | |
2065 | if (unlikely(nbytes > nr_bytes)) { | |
2066 | bio_nbytes += nr_bytes; | |
2067 | total_bytes += nr_bytes; | |
2068 | break; | |
2069 | } | |
2070 | ||
2071 | /* | |
2072 | * advance to the next vector | |
2073 | */ | |
2074 | next_idx++; | |
2075 | bio_nbytes += nbytes; | |
2076 | } | |
2077 | ||
2078 | total_bytes += nbytes; | |
2079 | nr_bytes -= nbytes; | |
2080 | ||
2081 | bio = req->bio; | |
2082 | if (bio) { | |
2083 | /* | |
2084 | * end more in this run, or just return 'not-done' | |
2085 | */ | |
2086 | if (unlikely(nr_bytes <= 0)) | |
2087 | break; | |
2088 | } | |
2089 | } | |
2090 | ||
2091 | /* | |
2092 | * completely done | |
2093 | */ | |
2094 | if (!req->bio) { | |
2095 | /* | |
2096 | * Reset counters so that the request stacking driver | |
2097 | * can find how many bytes remain in the request | |
2098 | * later. | |
2099 | */ | |
2100 | req->__data_len = 0; | |
2101 | return false; | |
2102 | } | |
2103 | ||
2104 | /* | |
2105 | * if the request wasn't completed, update state | |
2106 | */ | |
2107 | if (bio_nbytes) { | |
2108 | req_bio_endio(req, bio, bio_nbytes, error); | |
2109 | bio->bi_idx += next_idx; | |
2110 | bio_iovec(bio)->bv_offset += nr_bytes; | |
2111 | bio_iovec(bio)->bv_len -= nr_bytes; | |
2112 | } | |
2113 | ||
2114 | req->__data_len -= total_bytes; | |
2115 | req->buffer = bio_data(req->bio); | |
2116 | ||
2117 | /* update sector only for requests with clear definition of sector */ | |
2118 | if (req->cmd_type == REQ_TYPE_FS || (req->cmd_flags & REQ_DISCARD)) | |
2119 | req->__sector += total_bytes >> 9; | |
2120 | ||
2121 | /* mixed attributes always follow the first bio */ | |
2122 | if (req->cmd_flags & REQ_MIXED_MERGE) { | |
2123 | req->cmd_flags &= ~REQ_FAILFAST_MASK; | |
2124 | req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK; | |
2125 | } | |
2126 | ||
2127 | /* | |
2128 | * If total number of sectors is less than the first segment | |
2129 | * size, something has gone terribly wrong. | |
2130 | */ | |
2131 | if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { | |
2132 | printk(KERN_ERR "blk: request botched\n"); | |
2133 | req->__data_len = blk_rq_cur_bytes(req); | |
2134 | } | |
2135 | ||
2136 | /* recalculate the number of segments */ | |
2137 | blk_recalc_rq_segments(req); | |
2138 | ||
2139 | return true; | |
2140 | } | |
2141 | EXPORT_SYMBOL_GPL(blk_update_request); | |
2142 | ||
2143 | static bool blk_update_bidi_request(struct request *rq, int error, | |
2144 | unsigned int nr_bytes, | |
2145 | unsigned int bidi_bytes) | |
2146 | { | |
2147 | if (blk_update_request(rq, error, nr_bytes)) | |
2148 | return true; | |
2149 | ||
2150 | /* Bidi request must be completed as a whole */ | |
2151 | if (unlikely(blk_bidi_rq(rq)) && | |
2152 | blk_update_request(rq->next_rq, error, bidi_bytes)) | |
2153 | return true; | |
2154 | ||
2155 | if (blk_queue_add_random(rq->q)) | |
2156 | add_disk_randomness(rq->rq_disk); | |
2157 | ||
2158 | return false; | |
2159 | } | |
2160 | ||
2161 | /** | |
2162 | * blk_unprep_request - unprepare a request | |
2163 | * @req: the request | |
2164 | * | |
2165 | * This function makes a request ready for complete resubmission (or | |
2166 | * completion). It happens only after all error handling is complete, | |
2167 | * so represents the appropriate moment to deallocate any resources | |
2168 | * that were allocated to the request in the prep_rq_fn. The queue | |
2169 | * lock is held when calling this. | |
2170 | */ | |
2171 | void blk_unprep_request(struct request *req) | |
2172 | { | |
2173 | struct request_queue *q = req->q; | |
2174 | ||
2175 | req->cmd_flags &= ~REQ_DONTPREP; | |
2176 | if (q->unprep_rq_fn) | |
2177 | q->unprep_rq_fn(q, req); | |
2178 | } | |
2179 | EXPORT_SYMBOL_GPL(blk_unprep_request); | |
2180 | ||
2181 | /* | |
2182 | * queue lock must be held | |
2183 | */ | |
2184 | static void blk_finish_request(struct request *req, int error) | |
2185 | { | |
2186 | if (blk_rq_tagged(req)) | |
2187 | blk_queue_end_tag(req->q, req); | |
2188 | ||
2189 | BUG_ON(blk_queued_rq(req)); | |
2190 | ||
2191 | if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS) | |
2192 | laptop_io_completion(&req->q->backing_dev_info); | |
2193 | ||
2194 | blk_delete_timer(req); | |
2195 | ||
2196 | if (req->cmd_flags & REQ_DONTPREP) | |
2197 | blk_unprep_request(req); | |
2198 | ||
2199 | ||
2200 | blk_account_io_done(req); | |
2201 | ||
2202 | if (req->end_io) | |
2203 | req->end_io(req, error); | |
2204 | else { | |
2205 | if (blk_bidi_rq(req)) | |
2206 | __blk_put_request(req->next_rq->q, req->next_rq); | |
2207 | ||
2208 | __blk_put_request(req->q, req); | |
2209 | } | |
2210 | } | |
2211 | ||
2212 | /** | |
2213 | * blk_end_bidi_request - Complete a bidi request | |
2214 | * @rq: the request to complete | |
2215 | * @error: %0 for success, < %0 for error | |
2216 | * @nr_bytes: number of bytes to complete @rq | |
2217 | * @bidi_bytes: number of bytes to complete @rq->next_rq | |
2218 | * | |
2219 | * Description: | |
2220 | * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. | |
2221 | * Drivers that supports bidi can safely call this member for any | |
2222 | * type of request, bidi or uni. In the later case @bidi_bytes is | |
2223 | * just ignored. | |
2224 | * | |
2225 | * Return: | |
2226 | * %false - we are done with this request | |
2227 | * %true - still buffers pending for this request | |
2228 | **/ | |
2229 | static bool blk_end_bidi_request(struct request *rq, int error, | |
2230 | unsigned int nr_bytes, unsigned int bidi_bytes) | |
2231 | { | |
2232 | struct request_queue *q = rq->q; | |
2233 | unsigned long flags; | |
2234 | ||
2235 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) | |
2236 | return true; | |
2237 | ||
2238 | spin_lock_irqsave(q->queue_lock, flags); | |
2239 | blk_finish_request(rq, error); | |
2240 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2241 | ||
2242 | return false; | |
2243 | } | |
2244 | ||
2245 | /** | |
2246 | * __blk_end_bidi_request - Complete a bidi request with queue lock held | |
2247 | * @rq: the request to complete | |
2248 | * @error: %0 for success, < %0 for error | |
2249 | * @nr_bytes: number of bytes to complete @rq | |
2250 | * @bidi_bytes: number of bytes to complete @rq->next_rq | |
2251 | * | |
2252 | * Description: | |
2253 | * Identical to blk_end_bidi_request() except that queue lock is | |
2254 | * assumed to be locked on entry and remains so on return. | |
2255 | * | |
2256 | * Return: | |
2257 | * %false - we are done with this request | |
2258 | * %true - still buffers pending for this request | |
2259 | **/ | |
2260 | static bool __blk_end_bidi_request(struct request *rq, int error, | |
2261 | unsigned int nr_bytes, unsigned int bidi_bytes) | |
2262 | { | |
2263 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) | |
2264 | return true; | |
2265 | ||
2266 | blk_finish_request(rq, error); | |
2267 | ||
2268 | return false; | |
2269 | } | |
2270 | ||
2271 | /** | |
2272 | * blk_end_request - Helper function for drivers to complete the request. | |
2273 | * @rq: the request being processed | |
2274 | * @error: %0 for success, < %0 for error | |
2275 | * @nr_bytes: number of bytes to complete | |
2276 | * | |
2277 | * Description: | |
2278 | * Ends I/O on a number of bytes attached to @rq. | |
2279 | * If @rq has leftover, sets it up for the next range of segments. | |
2280 | * | |
2281 | * Return: | |
2282 | * %false - we are done with this request | |
2283 | * %true - still buffers pending for this request | |
2284 | **/ | |
2285 | bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes) | |
2286 | { | |
2287 | return blk_end_bidi_request(rq, error, nr_bytes, 0); | |
2288 | } | |
2289 | EXPORT_SYMBOL(blk_end_request); | |
2290 | ||
2291 | /** | |
2292 | * blk_end_request_all - Helper function for drives to finish the request. | |
2293 | * @rq: the request to finish | |
2294 | * @error: %0 for success, < %0 for error | |
2295 | * | |
2296 | * Description: | |
2297 | * Completely finish @rq. | |
2298 | */ | |
2299 | void blk_end_request_all(struct request *rq, int error) | |
2300 | { | |
2301 | bool pending; | |
2302 | unsigned int bidi_bytes = 0; | |
2303 | ||
2304 | if (unlikely(blk_bidi_rq(rq))) | |
2305 | bidi_bytes = blk_rq_bytes(rq->next_rq); | |
2306 | ||
2307 | pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); | |
2308 | BUG_ON(pending); | |
2309 | } | |
2310 | EXPORT_SYMBOL(blk_end_request_all); | |
2311 | ||
2312 | /** | |
2313 | * blk_end_request_cur - Helper function to finish the current request chunk. | |
2314 | * @rq: the request to finish the current chunk for | |
2315 | * @error: %0 for success, < %0 for error | |
2316 | * | |
2317 | * Description: | |
2318 | * Complete the current consecutively mapped chunk from @rq. | |
2319 | * | |
2320 | * Return: | |
2321 | * %false - we are done with this request | |
2322 | * %true - still buffers pending for this request | |
2323 | */ | |
2324 | bool blk_end_request_cur(struct request *rq, int error) | |
2325 | { | |
2326 | return blk_end_request(rq, error, blk_rq_cur_bytes(rq)); | |
2327 | } | |
2328 | EXPORT_SYMBOL(blk_end_request_cur); | |
2329 | ||
2330 | /** | |
2331 | * blk_end_request_err - Finish a request till the next failure boundary. | |
2332 | * @rq: the request to finish till the next failure boundary for | |
2333 | * @error: must be negative errno | |
2334 | * | |
2335 | * Description: | |
2336 | * Complete @rq till the next failure boundary. | |
2337 | * | |
2338 | * Return: | |
2339 | * %false - we are done with this request | |
2340 | * %true - still buffers pending for this request | |
2341 | */ | |
2342 | bool blk_end_request_err(struct request *rq, int error) | |
2343 | { | |
2344 | WARN_ON(error >= 0); | |
2345 | return blk_end_request(rq, error, blk_rq_err_bytes(rq)); | |
2346 | } | |
2347 | EXPORT_SYMBOL_GPL(blk_end_request_err); | |
2348 | ||
2349 | /** | |
2350 | * __blk_end_request - Helper function for drivers to complete the request. | |
2351 | * @rq: the request being processed | |
2352 | * @error: %0 for success, < %0 for error | |
2353 | * @nr_bytes: number of bytes to complete | |
2354 | * | |
2355 | * Description: | |
2356 | * Must be called with queue lock held unlike blk_end_request(). | |
2357 | * | |
2358 | * Return: | |
2359 | * %false - we are done with this request | |
2360 | * %true - still buffers pending for this request | |
2361 | **/ | |
2362 | bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) | |
2363 | { | |
2364 | return __blk_end_bidi_request(rq, error, nr_bytes, 0); | |
2365 | } | |
2366 | EXPORT_SYMBOL(__blk_end_request); | |
2367 | ||
2368 | /** | |
2369 | * __blk_end_request_all - Helper function for drives to finish the request. | |
2370 | * @rq: the request to finish | |
2371 | * @error: %0 for success, < %0 for error | |
2372 | * | |
2373 | * Description: | |
2374 | * Completely finish @rq. Must be called with queue lock held. | |
2375 | */ | |
2376 | void __blk_end_request_all(struct request *rq, int error) | |
2377 | { | |
2378 | bool pending; | |
2379 | unsigned int bidi_bytes = 0; | |
2380 | ||
2381 | if (unlikely(blk_bidi_rq(rq))) | |
2382 | bidi_bytes = blk_rq_bytes(rq->next_rq); | |
2383 | ||
2384 | pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); | |
2385 | BUG_ON(pending); | |
2386 | } | |
2387 | EXPORT_SYMBOL(__blk_end_request_all); | |
2388 | ||
2389 | /** | |
2390 | * __blk_end_request_cur - Helper function to finish the current request chunk. | |
2391 | * @rq: the request to finish the current chunk for | |
2392 | * @error: %0 for success, < %0 for error | |
2393 | * | |
2394 | * Description: | |
2395 | * Complete the current consecutively mapped chunk from @rq. Must | |
2396 | * be called with queue lock held. | |
2397 | * | |
2398 | * Return: | |
2399 | * %false - we are done with this request | |
2400 | * %true - still buffers pending for this request | |
2401 | */ | |
2402 | bool __blk_end_request_cur(struct request *rq, int error) | |
2403 | { | |
2404 | return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); | |
2405 | } | |
2406 | EXPORT_SYMBOL(__blk_end_request_cur); | |
2407 | ||
2408 | /** | |
2409 | * __blk_end_request_err - Finish a request till the next failure boundary. | |
2410 | * @rq: the request to finish till the next failure boundary for | |
2411 | * @error: must be negative errno | |
2412 | * | |
2413 | * Description: | |
2414 | * Complete @rq till the next failure boundary. Must be called | |
2415 | * with queue lock held. | |
2416 | * | |
2417 | * Return: | |
2418 | * %false - we are done with this request | |
2419 | * %true - still buffers pending for this request | |
2420 | */ | |
2421 | bool __blk_end_request_err(struct request *rq, int error) | |
2422 | { | |
2423 | WARN_ON(error >= 0); | |
2424 | return __blk_end_request(rq, error, blk_rq_err_bytes(rq)); | |
2425 | } | |
2426 | EXPORT_SYMBOL_GPL(__blk_end_request_err); | |
2427 | ||
2428 | void blk_rq_bio_prep(struct request_queue *q, struct request *rq, | |
2429 | struct bio *bio) | |
2430 | { | |
2431 | /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */ | |
2432 | rq->cmd_flags |= bio->bi_rw & REQ_WRITE; | |
2433 | ||
2434 | if (bio_has_data(bio)) { | |
2435 | rq->nr_phys_segments = bio_phys_segments(q, bio); | |
2436 | rq->buffer = bio_data(bio); | |
2437 | } | |
2438 | rq->__data_len = bio->bi_size; | |
2439 | rq->bio = rq->biotail = bio; | |
2440 | ||
2441 | if (bio->bi_bdev) | |
2442 | rq->rq_disk = bio->bi_bdev->bd_disk; | |
2443 | } | |
2444 | ||
2445 | #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE | |
2446 | /** | |
2447 | * rq_flush_dcache_pages - Helper function to flush all pages in a request | |
2448 | * @rq: the request to be flushed | |
2449 | * | |
2450 | * Description: | |
2451 | * Flush all pages in @rq. | |
2452 | */ | |
2453 | void rq_flush_dcache_pages(struct request *rq) | |
2454 | { | |
2455 | struct req_iterator iter; | |
2456 | struct bio_vec *bvec; | |
2457 | ||
2458 | rq_for_each_segment(bvec, rq, iter) | |
2459 | flush_dcache_page(bvec->bv_page); | |
2460 | } | |
2461 | EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); | |
2462 | #endif | |
2463 | ||
2464 | /** | |
2465 | * blk_lld_busy - Check if underlying low-level drivers of a device are busy | |
2466 | * @q : the queue of the device being checked | |
2467 | * | |
2468 | * Description: | |
2469 | * Check if underlying low-level drivers of a device are busy. | |
2470 | * If the drivers want to export their busy state, they must set own | |
2471 | * exporting function using blk_queue_lld_busy() first. | |
2472 | * | |
2473 | * Basically, this function is used only by request stacking drivers | |
2474 | * to stop dispatching requests to underlying devices when underlying | |
2475 | * devices are busy. This behavior helps more I/O merging on the queue | |
2476 | * of the request stacking driver and prevents I/O throughput regression | |
2477 | * on burst I/O load. | |
2478 | * | |
2479 | * Return: | |
2480 | * 0 - Not busy (The request stacking driver should dispatch request) | |
2481 | * 1 - Busy (The request stacking driver should stop dispatching request) | |
2482 | */ | |
2483 | int blk_lld_busy(struct request_queue *q) | |
2484 | { | |
2485 | if (q->lld_busy_fn) | |
2486 | return q->lld_busy_fn(q); | |
2487 | ||
2488 | return 0; | |
2489 | } | |
2490 | EXPORT_SYMBOL_GPL(blk_lld_busy); | |
2491 | ||
2492 | /** | |
2493 | * blk_rq_unprep_clone - Helper function to free all bios in a cloned request | |
2494 | * @rq: the clone request to be cleaned up | |
2495 | * | |
2496 | * Description: | |
2497 | * Free all bios in @rq for a cloned request. | |
2498 | */ | |
2499 | void blk_rq_unprep_clone(struct request *rq) | |
2500 | { | |
2501 | struct bio *bio; | |
2502 | ||
2503 | while ((bio = rq->bio) != NULL) { | |
2504 | rq->bio = bio->bi_next; | |
2505 | ||
2506 | bio_put(bio); | |
2507 | } | |
2508 | } | |
2509 | EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); | |
2510 | ||
2511 | /* | |
2512 | * Copy attributes of the original request to the clone request. | |
2513 | * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied. | |
2514 | */ | |
2515 | static void __blk_rq_prep_clone(struct request *dst, struct request *src) | |
2516 | { | |
2517 | dst->cpu = src->cpu; | |
2518 | dst->cmd_flags = (rq_data_dir(src) | REQ_NOMERGE); | |
2519 | if (src->cmd_flags & REQ_DISCARD) | |
2520 | dst->cmd_flags |= REQ_DISCARD; | |
2521 | dst->cmd_type = src->cmd_type; | |
2522 | dst->__sector = blk_rq_pos(src); | |
2523 | dst->__data_len = blk_rq_bytes(src); | |
2524 | dst->nr_phys_segments = src->nr_phys_segments; | |
2525 | dst->ioprio = src->ioprio; | |
2526 | dst->extra_len = src->extra_len; | |
2527 | } | |
2528 | ||
2529 | /** | |
2530 | * blk_rq_prep_clone - Helper function to setup clone request | |
2531 | * @rq: the request to be setup | |
2532 | * @rq_src: original request to be cloned | |
2533 | * @bs: bio_set that bios for clone are allocated from | |
2534 | * @gfp_mask: memory allocation mask for bio | |
2535 | * @bio_ctr: setup function to be called for each clone bio. | |
2536 | * Returns %0 for success, non %0 for failure. | |
2537 | * @data: private data to be passed to @bio_ctr | |
2538 | * | |
2539 | * Description: | |
2540 | * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. | |
2541 | * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense) | |
2542 | * are not copied, and copying such parts is the caller's responsibility. | |
2543 | * Also, pages which the original bios are pointing to are not copied | |
2544 | * and the cloned bios just point same pages. | |
2545 | * So cloned bios must be completed before original bios, which means | |
2546 | * the caller must complete @rq before @rq_src. | |
2547 | */ | |
2548 | int blk_rq_prep_clone(struct request *rq, struct request *rq_src, | |
2549 | struct bio_set *bs, gfp_t gfp_mask, | |
2550 | int (*bio_ctr)(struct bio *, struct bio *, void *), | |
2551 | void *data) | |
2552 | { | |
2553 | struct bio *bio, *bio_src; | |
2554 | ||
2555 | if (!bs) | |
2556 | bs = fs_bio_set; | |
2557 | ||
2558 | blk_rq_init(NULL, rq); | |
2559 | ||
2560 | __rq_for_each_bio(bio_src, rq_src) { | |
2561 | bio = bio_alloc_bioset(gfp_mask, bio_src->bi_max_vecs, bs); | |
2562 | if (!bio) | |
2563 | goto free_and_out; | |
2564 | ||
2565 | __bio_clone(bio, bio_src); | |
2566 | ||
2567 | if (bio_integrity(bio_src) && | |
2568 | bio_integrity_clone(bio, bio_src, gfp_mask, bs)) | |
2569 | goto free_and_out; | |
2570 | ||
2571 | if (bio_ctr && bio_ctr(bio, bio_src, data)) | |
2572 | goto free_and_out; | |
2573 | ||
2574 | if (rq->bio) { | |
2575 | rq->biotail->bi_next = bio; | |
2576 | rq->biotail = bio; | |
2577 | } else | |
2578 | rq->bio = rq->biotail = bio; | |
2579 | } | |
2580 | ||
2581 | __blk_rq_prep_clone(rq, rq_src); | |
2582 | ||
2583 | return 0; | |
2584 | ||
2585 | free_and_out: | |
2586 | if (bio) | |
2587 | bio_free(bio, bs); | |
2588 | blk_rq_unprep_clone(rq); | |
2589 | ||
2590 | return -ENOMEM; | |
2591 | } | |
2592 | EXPORT_SYMBOL_GPL(blk_rq_prep_clone); | |
2593 | ||
2594 | int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) | |
2595 | { | |
2596 | return queue_work(kblockd_workqueue, work); | |
2597 | } | |
2598 | EXPORT_SYMBOL(kblockd_schedule_work); | |
2599 | ||
2600 | int kblockd_schedule_delayed_work(struct request_queue *q, | |
2601 | struct delayed_work *dwork, unsigned long delay) | |
2602 | { | |
2603 | return queue_delayed_work(kblockd_workqueue, dwork, delay); | |
2604 | } | |
2605 | EXPORT_SYMBOL(kblockd_schedule_delayed_work); | |
2606 | ||
2607 | int __init blk_dev_init(void) | |
2608 | { | |
2609 | BUILD_BUG_ON(__REQ_NR_BITS > 8 * | |
2610 | sizeof(((struct request *)0)->cmd_flags)); | |
2611 | ||
2612 | kblockd_workqueue = create_workqueue("kblockd"); | |
2613 | if (!kblockd_workqueue) | |
2614 | panic("Failed to create kblockd\n"); | |
2615 | ||
2616 | request_cachep = kmem_cache_create("blkdev_requests", | |
2617 | sizeof(struct request), 0, SLAB_PANIC, NULL); | |
2618 | ||
2619 | blk_requestq_cachep = kmem_cache_create("blkdev_queue", | |
2620 | sizeof(struct request_queue), 0, SLAB_PANIC, NULL); | |
2621 | ||
2622 | return 0; | |
2623 | } |