Root/
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_bio_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 | |
68 | if (!new_io) { |
69 | part = rq->part; |
70 | part_stat_inc(cpu, part, merges[rw]); |
71 | } else { |
72 | part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); |
73 | if (!hd_struct_try_get(part)) { |
74 | /* |
75 | * The partition is already being removed, |
76 | * the request will be accounted on the disk only |
77 | * |
78 | * We take a reference on disk->part0 although that |
79 | * partition will never be deleted, so we can treat |
80 | * it as any other partition. |
81 | */ |
82 | part = &rq->rq_disk->part0; |
83 | hd_struct_get(part); |
84 | } |
85 | part_round_stats(cpu, part); |
86 | part_inc_in_flight(part, rw); |
87 | rq->part = part; |
88 | } |
89 | |
90 | part_stat_unlock(); |
91 | } |
92 | |
93 | void blk_queue_congestion_threshold(struct request_queue *q) |
94 | { |
95 | int nr; |
96 | |
97 | nr = q->nr_requests - (q->nr_requests / 8) + 1; |
98 | if (nr > q->nr_requests) |
99 | nr = q->nr_requests; |
100 | q->nr_congestion_on = nr; |
101 | |
102 | nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; |
103 | if (nr < 1) |
104 | nr = 1; |
105 | q->nr_congestion_off = nr; |
106 | } |
107 | |
108 | /** |
109 | * blk_get_backing_dev_info - get the address of a queue's backing_dev_info |
110 | * @bdev: device |
111 | * |
112 | * Locates the passed device's request queue and returns the address of its |
113 | * backing_dev_info |
114 | * |
115 | * Will return NULL if the request queue cannot be located. |
116 | */ |
117 | struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) |
118 | { |
119 | struct backing_dev_info *ret = NULL; |
120 | struct request_queue *q = bdev_get_queue(bdev); |
121 | |
122 | if (q) |
123 | ret = &q->backing_dev_info; |
124 | return ret; |
125 | } |
126 | EXPORT_SYMBOL(blk_get_backing_dev_info); |
127 | |
128 | void blk_rq_init(struct request_queue *q, struct request *rq) |
129 | { |
130 | memset(rq, 0, sizeof(*rq)); |
131 | |
132 | INIT_LIST_HEAD(&rq->queuelist); |
133 | INIT_LIST_HEAD(&rq->timeout_list); |
134 | rq->cpu = -1; |
135 | rq->q = q; |
136 | rq->__sector = (sector_t) -1; |
137 | INIT_HLIST_NODE(&rq->hash); |
138 | RB_CLEAR_NODE(&rq->rb_node); |
139 | rq->cmd = rq->__cmd; |
140 | rq->cmd_len = BLK_MAX_CDB; |
141 | rq->tag = -1; |
142 | rq->ref_count = 1; |
143 | rq->start_time = jiffies; |
144 | set_start_time_ns(rq); |
145 | rq->part = NULL; |
146 | } |
147 | EXPORT_SYMBOL(blk_rq_init); |
148 | |
149 | static void req_bio_endio(struct request *rq, struct bio *bio, |
150 | unsigned int nbytes, int error) |
151 | { |
152 | struct request_queue *q = rq->q; |
153 | |
154 | if (&q->flush_rq != rq) { |
155 | if (error) |
156 | clear_bit(BIO_UPTODATE, &bio->bi_flags); |
157 | else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) |
158 | error = -EIO; |
159 | |
160 | if (unlikely(nbytes > bio->bi_size)) { |
161 | printk(KERN_ERR "%s: want %u bytes done, %u left\n", |
162 | __func__, nbytes, bio->bi_size); |
163 | nbytes = bio->bi_size; |
164 | } |
165 | |
166 | if (unlikely(rq->cmd_flags & REQ_QUIET)) |
167 | set_bit(BIO_QUIET, &bio->bi_flags); |
168 | |
169 | bio->bi_size -= nbytes; |
170 | bio->bi_sector += (nbytes >> 9); |
171 | |
172 | if (bio_integrity(bio)) |
173 | bio_integrity_advance(bio, nbytes); |
174 | |
175 | if (bio->bi_size == 0) |
176 | bio_endio(bio, error); |
177 | } else { |
178 | /* |
179 | * Okay, this is the sequenced flush request in |
180 | * progress, just record the error; |
181 | */ |
182 | if (error && !q->flush_err) |
183 | q->flush_err = error; |
184 | } |
185 | } |
186 | |
187 | void blk_dump_rq_flags(struct request *rq, char *msg) |
188 | { |
189 | int bit; |
190 | |
191 | printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg, |
192 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, |
193 | rq->cmd_flags); |
194 | |
195 | printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", |
196 | (unsigned long long)blk_rq_pos(rq), |
197 | blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); |
198 | printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n", |
199 | rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq)); |
200 | |
201 | if (rq->cmd_type == REQ_TYPE_BLOCK_PC) { |
202 | printk(KERN_INFO " cdb: "); |
203 | for (bit = 0; bit < BLK_MAX_CDB; bit++) |
204 | printk("%02x ", rq->cmd[bit]); |
205 | printk("\n"); |
206 | } |
207 | } |
208 | EXPORT_SYMBOL(blk_dump_rq_flags); |
209 | |
210 | /* |
211 | * "plug" the device if there are no outstanding requests: this will |
212 | * force the transfer to start only after we have put all the requests |
213 | * on the list. |
214 | * |
215 | * This is called with interrupts off and no requests on the queue and |
216 | * with the queue lock held. |
217 | */ |
218 | void blk_plug_device(struct request_queue *q) |
219 | { |
220 | WARN_ON(!irqs_disabled()); |
221 | |
222 | /* |
223 | * don't plug a stopped queue, it must be paired with blk_start_queue() |
224 | * which will restart the queueing |
225 | */ |
226 | if (blk_queue_stopped(q)) |
227 | return; |
228 | |
229 | if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) { |
230 | mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); |
231 | trace_block_plug(q); |
232 | } |
233 | } |
234 | EXPORT_SYMBOL(blk_plug_device); |
235 | |
236 | /** |
237 | * blk_plug_device_unlocked - plug a device without queue lock held |
238 | * @q: The &struct request_queue to plug |
239 | * |
240 | * Description: |
241 | * Like @blk_plug_device(), but grabs the queue lock and disables |
242 | * interrupts. |
243 | **/ |
244 | void blk_plug_device_unlocked(struct request_queue *q) |
245 | { |
246 | unsigned long flags; |
247 | |
248 | spin_lock_irqsave(q->queue_lock, flags); |
249 | blk_plug_device(q); |
250 | spin_unlock_irqrestore(q->queue_lock, flags); |
251 | } |
252 | EXPORT_SYMBOL(blk_plug_device_unlocked); |
253 | |
254 | /* |
255 | * remove the queue from the plugged list, if present. called with |
256 | * queue lock held and interrupts disabled. |
257 | */ |
258 | int blk_remove_plug(struct request_queue *q) |
259 | { |
260 | WARN_ON(!irqs_disabled()); |
261 | |
262 | if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q)) |
263 | return 0; |
264 | |
265 | del_timer(&q->unplug_timer); |
266 | return 1; |
267 | } |
268 | EXPORT_SYMBOL(blk_remove_plug); |
269 | |
270 | /* |
271 | * remove the plug and let it rip.. |
272 | */ |
273 | void __generic_unplug_device(struct request_queue *q) |
274 | { |
275 | if (unlikely(blk_queue_stopped(q))) |
276 | return; |
277 | if (!blk_remove_plug(q) && !blk_queue_nonrot(q)) |
278 | return; |
279 | |
280 | q->request_fn(q); |
281 | } |
282 | |
283 | /** |
284 | * generic_unplug_device - fire a request queue |
285 | * @q: The &struct request_queue in question |
286 | * |
287 | * Description: |
288 | * Linux uses plugging to build bigger requests queues before letting |
289 | * the device have at them. If a queue is plugged, the I/O scheduler |
290 | * is still adding and merging requests on the queue. Once the queue |
291 | * gets unplugged, the request_fn defined for the queue is invoked and |
292 | * transfers started. |
293 | **/ |
294 | void generic_unplug_device(struct request_queue *q) |
295 | { |
296 | if (blk_queue_plugged(q)) { |
297 | spin_lock_irq(q->queue_lock); |
298 | __generic_unplug_device(q); |
299 | spin_unlock_irq(q->queue_lock); |
300 | } |
301 | } |
302 | EXPORT_SYMBOL(generic_unplug_device); |
303 | |
304 | static void blk_backing_dev_unplug(struct backing_dev_info *bdi, |
305 | struct page *page) |
306 | { |
307 | struct request_queue *q = bdi->unplug_io_data; |
308 | |
309 | blk_unplug(q); |
310 | } |
311 | |
312 | void blk_unplug_work(struct work_struct *work) |
313 | { |
314 | struct request_queue *q = |
315 | container_of(work, struct request_queue, unplug_work); |
316 | |
317 | trace_block_unplug_io(q); |
318 | q->unplug_fn(q); |
319 | } |
320 | |
321 | void blk_unplug_timeout(unsigned long data) |
322 | { |
323 | struct request_queue *q = (struct request_queue *)data; |
324 | |
325 | trace_block_unplug_timer(q); |
326 | kblockd_schedule_work(q, &q->unplug_work); |
327 | } |
328 | |
329 | void blk_unplug(struct request_queue *q) |
330 | { |
331 | /* |
332 | * devices don't necessarily have an ->unplug_fn defined |
333 | */ |
334 | if (q->unplug_fn) { |
335 | trace_block_unplug_io(q); |
336 | q->unplug_fn(q); |
337 | } |
338 | } |
339 | EXPORT_SYMBOL(blk_unplug); |
340 | |
341 | /** |
342 | * blk_start_queue - restart a previously stopped queue |
343 | * @q: The &struct request_queue in question |
344 | * |
345 | * Description: |
346 | * blk_start_queue() will clear the stop flag on the queue, and call |
347 | * the request_fn for the queue if it was in a stopped state when |
348 | * entered. Also see blk_stop_queue(). Queue lock must be held. |
349 | **/ |
350 | void blk_start_queue(struct request_queue *q) |
351 | { |
352 | WARN_ON(!irqs_disabled()); |
353 | |
354 | queue_flag_clear(QUEUE_FLAG_STOPPED, q); |
355 | __blk_run_queue(q, false); |
356 | } |
357 | EXPORT_SYMBOL(blk_start_queue); |
358 | |
359 | /** |
360 | * blk_stop_queue - stop a queue |
361 | * @q: The &struct request_queue in question |
362 | * |
363 | * Description: |
364 | * The Linux block layer assumes that a block driver will consume all |
365 | * entries on the request queue when the request_fn strategy is called. |
366 | * Often this will not happen, because of hardware limitations (queue |
367 | * depth settings). If a device driver gets a 'queue full' response, |
368 | * or if it simply chooses not to queue more I/O at one point, it can |
369 | * call this function to prevent the request_fn from being called until |
370 | * the driver has signalled it's ready to go again. This happens by calling |
371 | * blk_start_queue() to restart queue operations. Queue lock must be held. |
372 | **/ |
373 | void blk_stop_queue(struct request_queue *q) |
374 | { |
375 | blk_remove_plug(q); |
376 | queue_flag_set(QUEUE_FLAG_STOPPED, q); |
377 | } |
378 | EXPORT_SYMBOL(blk_stop_queue); |
379 | |
380 | /** |
381 | * blk_sync_queue - cancel any pending callbacks on a queue |
382 | * @q: the queue |
383 | * |
384 | * Description: |
385 | * The block layer may perform asynchronous callback activity |
386 | * on a queue, such as calling the unplug function after a timeout. |
387 | * A block device may call blk_sync_queue to ensure that any |
388 | * such activity is cancelled, thus allowing it to release resources |
389 | * that the callbacks might use. The caller must already have made sure |
390 | * that its ->make_request_fn will not re-add plugging prior to calling |
391 | * this function. |
392 | * |
393 | */ |
394 | void blk_sync_queue(struct request_queue *q) |
395 | { |
396 | del_timer_sync(&q->unplug_timer); |
397 | del_timer_sync(&q->timeout); |
398 | cancel_work_sync(&q->unplug_work); |
399 | throtl_shutdown_timer_wq(q); |
400 | } |
401 | EXPORT_SYMBOL(blk_sync_queue); |
402 | |
403 | /** |
404 | * __blk_run_queue - run a single device queue |
405 | * @q: The queue to run |
406 | * @force_kblockd: Don't run @q->request_fn directly. Use kblockd. |
407 | * |
408 | * Description: |
409 | * See @blk_run_queue. This variant must be called with the queue lock |
410 | * held and interrupts disabled. |
411 | * |
412 | */ |
413 | void __blk_run_queue(struct request_queue *q, bool force_kblockd) |
414 | { |
415 | blk_remove_plug(q); |
416 | |
417 | if (unlikely(blk_queue_stopped(q))) |
418 | return; |
419 | |
420 | if (elv_queue_empty(q)) |
421 | return; |
422 | |
423 | /* |
424 | * Only recurse once to avoid overrunning the stack, let the unplug |
425 | * handling reinvoke the handler shortly if we already got there. |
426 | */ |
427 | if (!force_kblockd && !queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { |
428 | q->request_fn(q); |
429 | queue_flag_clear(QUEUE_FLAG_REENTER, q); |
430 | } else { |
431 | queue_flag_set(QUEUE_FLAG_PLUGGED, q); |
432 | kblockd_schedule_work(q, &q->unplug_work); |
433 | } |
434 | } |
435 | EXPORT_SYMBOL(__blk_run_queue); |
436 | |
437 | /** |
438 | * blk_run_queue - run a single device queue |
439 | * @q: The queue to run |
440 | * |
441 | * Description: |
442 | * Invoke request handling on this queue, if it has pending work to do. |
443 | * May be used to restart queueing when a request has completed. |
444 | */ |
445 | void blk_run_queue(struct request_queue *q) |
446 | { |
447 | unsigned long flags; |
448 | |
449 | spin_lock_irqsave(q->queue_lock, flags); |
450 | __blk_run_queue(q, false); |
451 | spin_unlock_irqrestore(q->queue_lock, flags); |
452 | } |
453 | EXPORT_SYMBOL(blk_run_queue); |
454 | |
455 | void blk_put_queue(struct request_queue *q) |
456 | { |
457 | kobject_put(&q->kobj); |
458 | } |
459 | |
460 | void blk_cleanup_queue(struct request_queue *q) |
461 | { |
462 | /* |
463 | * We know we have process context here, so we can be a little |
464 | * cautious and ensure that pending block actions on this device |
465 | * are done before moving on. Going into this function, we should |
466 | * not have processes doing IO to this device. |
467 | */ |
468 | blk_sync_queue(q); |
469 | |
470 | del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer); |
471 | mutex_lock(&q->sysfs_lock); |
472 | queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q); |
473 | mutex_unlock(&q->sysfs_lock); |
474 | |
475 | if (q->elevator) |
476 | elevator_exit(q->elevator); |
477 | |
478 | blk_put_queue(q); |
479 | } |
480 | EXPORT_SYMBOL(blk_cleanup_queue); |
481 | |
482 | static int blk_init_free_list(struct request_queue *q) |
483 | { |
484 | struct request_list *rl = &q->rq; |
485 | |
486 | if (unlikely(rl->rq_pool)) |
487 | return 0; |
488 | |
489 | rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; |
490 | rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; |
491 | rl->elvpriv = 0; |
492 | init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); |
493 | init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); |
494 | |
495 | rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
496 | mempool_free_slab, request_cachep, q->node); |
497 | |
498 | if (!rl->rq_pool) |
499 | return -ENOMEM; |
500 | |
501 | return 0; |
502 | } |
503 | |
504 | struct request_queue *blk_alloc_queue(gfp_t gfp_mask) |
505 | { |
506 | return blk_alloc_queue_node(gfp_mask, -1); |
507 | } |
508 | EXPORT_SYMBOL(blk_alloc_queue); |
509 | |
510 | struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) |
511 | { |
512 | struct request_queue *q; |
513 | int err; |
514 | |
515 | q = kmem_cache_alloc_node(blk_requestq_cachep, |
516 | gfp_mask | __GFP_ZERO, node_id); |
517 | if (!q) |
518 | return NULL; |
519 | |
520 | q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; |
521 | q->backing_dev_info.unplug_io_data = q; |
522 | q->backing_dev_info.ra_pages = |
523 | (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; |
524 | q->backing_dev_info.state = 0; |
525 | q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; |
526 | q->backing_dev_info.name = "block"; |
527 | |
528 | err = bdi_init(&q->backing_dev_info); |
529 | if (err) { |
530 | kmem_cache_free(blk_requestq_cachep, q); |
531 | return NULL; |
532 | } |
533 | |
534 | if (blk_throtl_init(q)) { |
535 | kmem_cache_free(blk_requestq_cachep, q); |
536 | return NULL; |
537 | } |
538 | |
539 | setup_timer(&q->backing_dev_info.laptop_mode_wb_timer, |
540 | laptop_mode_timer_fn, (unsigned long) q); |
541 | init_timer(&q->unplug_timer); |
542 | setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); |
543 | INIT_LIST_HEAD(&q->timeout_list); |
544 | INIT_LIST_HEAD(&q->pending_flushes); |
545 | INIT_WORK(&q->unplug_work, blk_unplug_work); |
546 | |
547 | kobject_init(&q->kobj, &blk_queue_ktype); |
548 | |
549 | mutex_init(&q->sysfs_lock); |
550 | spin_lock_init(&q->__queue_lock); |
551 | |
552 | return q; |
553 | } |
554 | EXPORT_SYMBOL(blk_alloc_queue_node); |
555 | |
556 | /** |
557 | * blk_init_queue - prepare a request queue for use with a block device |
558 | * @rfn: The function to be called to process requests that have been |
559 | * placed on the queue. |
560 | * @lock: Request queue spin lock |
561 | * |
562 | * Description: |
563 | * If a block device wishes to use the standard request handling procedures, |
564 | * which sorts requests and coalesces adjacent requests, then it must |
565 | * call blk_init_queue(). The function @rfn will be called when there |
566 | * are requests on the queue that need to be processed. If the device |
567 | * supports plugging, then @rfn may not be called immediately when requests |
568 | * are available on the queue, but may be called at some time later instead. |
569 | * Plugged queues are generally unplugged when a buffer belonging to one |
570 | * of the requests on the queue is needed, or due to memory pressure. |
571 | * |
572 | * @rfn is not required, or even expected, to remove all requests off the |
573 | * queue, but only as many as it can handle at a time. If it does leave |
574 | * requests on the queue, it is responsible for arranging that the requests |
575 | * get dealt with eventually. |
576 | * |
577 | * The queue spin lock must be held while manipulating the requests on the |
578 | * request queue; this lock will be taken also from interrupt context, so irq |
579 | * disabling is needed for it. |
580 | * |
581 | * Function returns a pointer to the initialized request queue, or %NULL if |
582 | * it didn't succeed. |
583 | * |
584 | * Note: |
585 | * blk_init_queue() must be paired with a blk_cleanup_queue() call |
586 | * when the block device is deactivated (such as at module unload). |
587 | **/ |
588 | |
589 | struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) |
590 | { |
591 | return blk_init_queue_node(rfn, lock, -1); |
592 | } |
593 | EXPORT_SYMBOL(blk_init_queue); |
594 | |
595 | struct request_queue * |
596 | blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) |
597 | { |
598 | struct request_queue *uninit_q, *q; |
599 | |
600 | uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id); |
601 | if (!uninit_q) |
602 | return NULL; |
603 | |
604 | q = blk_init_allocated_queue_node(uninit_q, rfn, lock, node_id); |
605 | if (!q) |
606 | blk_cleanup_queue(uninit_q); |
607 | |
608 | return q; |
609 | } |
610 | EXPORT_SYMBOL(blk_init_queue_node); |
611 | |
612 | struct request_queue * |
613 | blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, |
614 | spinlock_t *lock) |
615 | { |
616 | return blk_init_allocated_queue_node(q, rfn, lock, -1); |
617 | } |
618 | EXPORT_SYMBOL(blk_init_allocated_queue); |
619 | |
620 | struct request_queue * |
621 | blk_init_allocated_queue_node(struct request_queue *q, request_fn_proc *rfn, |
622 | spinlock_t *lock, int node_id) |
623 | { |
624 | if (!q) |
625 | return NULL; |
626 | |
627 | q->node = node_id; |
628 | if (blk_init_free_list(q)) |
629 | return NULL; |
630 | |
631 | q->request_fn = rfn; |
632 | q->prep_rq_fn = NULL; |
633 | q->unprep_rq_fn = NULL; |
634 | q->unplug_fn = generic_unplug_device; |
635 | q->queue_flags = QUEUE_FLAG_DEFAULT; |
636 | q->queue_lock = lock; |
637 | |
638 | /* |
639 | * This also sets hw/phys segments, boundary and size |
640 | */ |
641 | blk_queue_make_request(q, __make_request); |
642 | |
643 | q->sg_reserved_size = INT_MAX; |
644 | |
645 | /* |
646 | * all done |
647 | */ |
648 | if (!elevator_init(q, NULL)) { |
649 | blk_queue_congestion_threshold(q); |
650 | return q; |
651 | } |
652 | |
653 | return NULL; |
654 | } |
655 | EXPORT_SYMBOL(blk_init_allocated_queue_node); |
656 | |
657 | int blk_get_queue(struct request_queue *q) |
658 | { |
659 | if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { |
660 | kobject_get(&q->kobj); |
661 | return 0; |
662 | } |
663 | |
664 | return 1; |
665 | } |
666 | |
667 | static inline void blk_free_request(struct request_queue *q, struct request *rq) |
668 | { |
669 | if (rq->cmd_flags & REQ_ELVPRIV) |
670 | elv_put_request(q, rq); |
671 | mempool_free(rq, q->rq.rq_pool); |
672 | } |
673 | |
674 | static struct request * |
675 | blk_alloc_request(struct request_queue *q, int flags, int priv, gfp_t gfp_mask) |
676 | { |
677 | struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); |
678 | |
679 | if (!rq) |
680 | return NULL; |
681 | |
682 | blk_rq_init(q, rq); |
683 | |
684 | rq->cmd_flags = flags | REQ_ALLOCED; |
685 | |
686 | if (priv) { |
687 | if (unlikely(elv_set_request(q, rq, gfp_mask))) { |
688 | mempool_free(rq, q->rq.rq_pool); |
689 | return NULL; |
690 | } |
691 | rq->cmd_flags |= REQ_ELVPRIV; |
692 | } |
693 | |
694 | return rq; |
695 | } |
696 | |
697 | /* |
698 | * ioc_batching returns true if the ioc is a valid batching request and |
699 | * should be given priority access to a request. |
700 | */ |
701 | static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) |
702 | { |
703 | if (!ioc) |
704 | return 0; |
705 | |
706 | /* |
707 | * Make sure the process is able to allocate at least 1 request |
708 | * even if the batch times out, otherwise we could theoretically |
709 | * lose wakeups. |
710 | */ |
711 | return ioc->nr_batch_requests == q->nr_batching || |
712 | (ioc->nr_batch_requests > 0 |
713 | && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); |
714 | } |
715 | |
716 | /* |
717 | * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This |
718 | * will cause the process to be a "batcher" on all queues in the system. This |
719 | * is the behaviour we want though - once it gets a wakeup it should be given |
720 | * a nice run. |
721 | */ |
722 | static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) |
723 | { |
724 | if (!ioc || ioc_batching(q, ioc)) |
725 | return; |
726 | |
727 | ioc->nr_batch_requests = q->nr_batching; |
728 | ioc->last_waited = jiffies; |
729 | } |
730 | |
731 | static void __freed_request(struct request_queue *q, int sync) |
732 | { |
733 | struct request_list *rl = &q->rq; |
734 | |
735 | if (rl->count[sync] < queue_congestion_off_threshold(q)) |
736 | blk_clear_queue_congested(q, sync); |
737 | |
738 | if (rl->count[sync] + 1 <= q->nr_requests) { |
739 | if (waitqueue_active(&rl->wait[sync])) |
740 | wake_up(&rl->wait[sync]); |
741 | |
742 | blk_clear_queue_full(q, sync); |
743 | } |
744 | } |
745 | |
746 | /* |
747 | * A request has just been released. Account for it, update the full and |
748 | * congestion status, wake up any waiters. Called under q->queue_lock. |
749 | */ |
750 | static void freed_request(struct request_queue *q, int sync, int priv) |
751 | { |
752 | struct request_list *rl = &q->rq; |
753 | |
754 | rl->count[sync]--; |
755 | if (priv) |
756 | rl->elvpriv--; |
757 | |
758 | __freed_request(q, sync); |
759 | |
760 | if (unlikely(rl->starved[sync ^ 1])) |
761 | __freed_request(q, sync ^ 1); |
762 | } |
763 | |
764 | /* |
765 | * Get a free request, queue_lock must be held. |
766 | * Returns NULL on failure, with queue_lock held. |
767 | * Returns !NULL on success, with queue_lock *not held*. |
768 | */ |
769 | static struct request *get_request(struct request_queue *q, int rw_flags, |
770 | struct bio *bio, gfp_t gfp_mask) |
771 | { |
772 | struct request *rq = NULL; |
773 | struct request_list *rl = &q->rq; |
774 | struct io_context *ioc = NULL; |
775 | const bool is_sync = rw_is_sync(rw_flags) != 0; |
776 | int may_queue, priv; |
777 | |
778 | may_queue = elv_may_queue(q, rw_flags); |
779 | if (may_queue == ELV_MQUEUE_NO) |
780 | goto rq_starved; |
781 | |
782 | if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { |
783 | if (rl->count[is_sync]+1 >= q->nr_requests) { |
784 | ioc = current_io_context(GFP_ATOMIC, q->node); |
785 | /* |
786 | * The queue will fill after this allocation, so set |
787 | * it as full, and mark this process as "batching". |
788 | * This process will be allowed to complete a batch of |
789 | * requests, others will be blocked. |
790 | */ |
791 | if (!blk_queue_full(q, is_sync)) { |
792 | ioc_set_batching(q, ioc); |
793 | blk_set_queue_full(q, is_sync); |
794 | } else { |
795 | if (may_queue != ELV_MQUEUE_MUST |
796 | && !ioc_batching(q, ioc)) { |
797 | /* |
798 | * The queue is full and the allocating |
799 | * process is not a "batcher", and not |
800 | * exempted by the IO scheduler |
801 | */ |
802 | goto out; |
803 | } |
804 | } |
805 | } |
806 | blk_set_queue_congested(q, is_sync); |
807 | } |
808 | |
809 | /* |
810 | * Only allow batching queuers to allocate up to 50% over the defined |
811 | * limit of requests, otherwise we could have thousands of requests |
812 | * allocated with any setting of ->nr_requests |
813 | */ |
814 | if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) |
815 | goto out; |
816 | |
817 | rl->count[is_sync]++; |
818 | rl->starved[is_sync] = 0; |
819 | |
820 | priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
821 | if (priv) |
822 | rl->elvpriv++; |
823 | |
824 | if (blk_queue_io_stat(q)) |
825 | rw_flags |= REQ_IO_STAT; |
826 | spin_unlock_irq(q->queue_lock); |
827 | |
828 | rq = blk_alloc_request(q, rw_flags, priv, gfp_mask); |
829 | if (unlikely(!rq)) { |
830 | /* |
831 | * Allocation failed presumably due to memory. Undo anything |
832 | * we might have messed up. |
833 | * |
834 | * Allocating task should really be put onto the front of the |
835 | * wait queue, but this is pretty rare. |
836 | */ |
837 | spin_lock_irq(q->queue_lock); |
838 | freed_request(q, is_sync, priv); |
839 | |
840 | /* |
841 | * in the very unlikely event that allocation failed and no |
842 | * requests for this direction was pending, mark us starved |
843 | * so that freeing of a request in the other direction will |
844 | * notice us. another possible fix would be to split the |
845 | * rq mempool into READ and WRITE |
846 | */ |
847 | rq_starved: |
848 | if (unlikely(rl->count[is_sync] == 0)) |
849 | rl->starved[is_sync] = 1; |
850 | |
851 | goto out; |
852 | } |
853 | |
854 | /* |
855 | * ioc may be NULL here, and ioc_batching will be false. That's |
856 | * OK, if the queue is under the request limit then requests need |
857 | * not count toward the nr_batch_requests limit. There will always |
858 | * be some limit enforced by BLK_BATCH_TIME. |
859 | */ |
860 | if (ioc_batching(q, ioc)) |
861 | ioc->nr_batch_requests--; |
862 | |
863 | trace_block_getrq(q, bio, rw_flags & 1); |
864 | out: |
865 | return rq; |
866 | } |
867 | |
868 | /* |
869 | * No available requests for this queue, unplug the device and wait for some |
870 | * requests to become available. |
871 | * |
872 | * Called with q->queue_lock held, and returns with it unlocked. |
873 | */ |
874 | static struct request *get_request_wait(struct request_queue *q, int rw_flags, |
875 | struct bio *bio) |
876 | { |
877 | const bool is_sync = rw_is_sync(rw_flags) != 0; |
878 | struct request *rq; |
879 | |
880 | rq = get_request(q, rw_flags, bio, GFP_NOIO); |
881 | while (!rq) { |
882 | DEFINE_WAIT(wait); |
883 | struct io_context *ioc; |
884 | struct request_list *rl = &q->rq; |
885 | |
886 | prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, |
887 | TASK_UNINTERRUPTIBLE); |
888 | |
889 | trace_block_sleeprq(q, bio, rw_flags & 1); |
890 | |
891 | __generic_unplug_device(q); |
892 | spin_unlock_irq(q->queue_lock); |
893 | io_schedule(); |
894 | |
895 | /* |
896 | * After sleeping, we become a "batching" process and |
897 | * will be able to allocate at least one request, and |
898 | * up to a big batch of them for a small period time. |
899 | * See ioc_batching, ioc_set_batching |
900 | */ |
901 | ioc = current_io_context(GFP_NOIO, q->node); |
902 | ioc_set_batching(q, ioc); |
903 | |
904 | spin_lock_irq(q->queue_lock); |
905 | finish_wait(&rl->wait[is_sync], &wait); |
906 | |
907 | rq = get_request(q, rw_flags, bio, GFP_NOIO); |
908 | }; |
909 | |
910 | return rq; |
911 | } |
912 | |
913 | struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) |
914 | { |
915 | struct request *rq; |
916 | |
917 | BUG_ON(rw != READ && rw != WRITE); |
918 | |
919 | spin_lock_irq(q->queue_lock); |
920 | if (gfp_mask & __GFP_WAIT) { |
921 | rq = get_request_wait(q, rw, NULL); |
922 | } else { |
923 | rq = get_request(q, rw, NULL, gfp_mask); |
924 | if (!rq) |
925 | spin_unlock_irq(q->queue_lock); |
926 | } |
927 | /* q->queue_lock is unlocked at this point */ |
928 | |
929 | return rq; |
930 | } |
931 | EXPORT_SYMBOL(blk_get_request); |
932 | |
933 | /** |
934 | * blk_make_request - given a bio, allocate a corresponding struct request. |
935 | * @q: target request queue |
936 | * @bio: The bio describing the memory mappings that will be submitted for IO. |
937 | * It may be a chained-bio properly constructed by block/bio layer. |
938 | * @gfp_mask: gfp flags to be used for memory allocation |
939 | * |
940 | * blk_make_request is the parallel of generic_make_request for BLOCK_PC |
941 | * type commands. Where the struct request needs to be farther initialized by |
942 | * the caller. It is passed a &struct bio, which describes the memory info of |
943 | * the I/O transfer. |
944 | * |
945 | * The caller of blk_make_request must make sure that bi_io_vec |
946 | * are set to describe the memory buffers. That bio_data_dir() will return |
947 | * the needed direction of the request. (And all bio's in the passed bio-chain |
948 | * are properly set accordingly) |
949 | * |
950 | * If called under none-sleepable conditions, mapped bio buffers must not |
951 | * need bouncing, by calling the appropriate masked or flagged allocator, |
952 | * suitable for the target device. Otherwise the call to blk_queue_bounce will |
953 | * BUG. |
954 | * |
955 | * WARNING: When allocating/cloning a bio-chain, careful consideration should be |
956 | * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for |
957 | * anything but the first bio in the chain. Otherwise you risk waiting for IO |
958 | * completion of a bio that hasn't been submitted yet, thus resulting in a |
959 | * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead |
960 | * of bio_alloc(), as that avoids the mempool deadlock. |
961 | * If possible a big IO should be split into smaller parts when allocation |
962 | * fails. Partial allocation should not be an error, or you risk a live-lock. |
963 | */ |
964 | struct request *blk_make_request(struct request_queue *q, struct bio *bio, |
965 | gfp_t gfp_mask) |
966 | { |
967 | struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask); |
968 | |
969 | if (unlikely(!rq)) |
970 | return ERR_PTR(-ENOMEM); |
971 | |
972 | for_each_bio(bio) { |
973 | struct bio *bounce_bio = bio; |
974 | int ret; |
975 | |
976 | blk_queue_bounce(q, &bounce_bio); |
977 | ret = blk_rq_append_bio(q, rq, bounce_bio); |
978 | if (unlikely(ret)) { |
979 | blk_put_request(rq); |
980 | return ERR_PTR(ret); |
981 | } |
982 | } |
983 | |
984 | return rq; |
985 | } |
986 | EXPORT_SYMBOL(blk_make_request); |
987 | |
988 | /** |
989 | * blk_requeue_request - put a request back on queue |
990 | * @q: request queue where request should be inserted |
991 | * @rq: request to be inserted |
992 | * |
993 | * Description: |
994 | * Drivers often keep queueing requests until the hardware cannot accept |
995 | * more, when that condition happens we need to put the request back |
996 | * on the queue. Must be called with queue lock held. |
997 | */ |
998 | void blk_requeue_request(struct request_queue *q, struct request *rq) |
999 | { |
1000 | blk_delete_timer(rq); |
1001 | blk_clear_rq_complete(rq); |
1002 | trace_block_rq_requeue(q, rq); |
1003 | |
1004 | if (blk_rq_tagged(rq)) |
1005 | blk_queue_end_tag(q, rq); |
1006 | |
1007 | BUG_ON(blk_queued_rq(rq)); |
1008 | |
1009 | elv_requeue_request(q, rq); |
1010 | } |
1011 | EXPORT_SYMBOL(blk_requeue_request); |
1012 | |
1013 | /** |
1014 | * blk_insert_request - insert a special request into a request queue |
1015 | * @q: request queue where request should be inserted |
1016 | * @rq: request to be inserted |
1017 | * @at_head: insert request at head or tail of queue |
1018 | * @data: private data |
1019 | * |
1020 | * Description: |
1021 | * Many block devices need to execute commands asynchronously, so they don't |
1022 | * block the whole kernel from preemption during request execution. This is |
1023 | * accomplished normally by inserting aritficial requests tagged as |
1024 | * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them |
1025 | * be scheduled for actual execution by the request queue. |
1026 | * |
1027 | * We have the option of inserting the head or the tail of the queue. |
1028 | * Typically we use the tail for new ioctls and so forth. We use the head |
1029 | * of the queue for things like a QUEUE_FULL message from a device, or a |
1030 | * host that is unable to accept a particular command. |
1031 | */ |
1032 | void blk_insert_request(struct request_queue *q, struct request *rq, |
1033 | int at_head, void *data) |
1034 | { |
1035 | int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; |
1036 | unsigned long flags; |
1037 | |
1038 | /* |
1039 | * tell I/O scheduler that this isn't a regular read/write (ie it |
1040 | * must not attempt merges on this) and that it acts as a soft |
1041 | * barrier |
1042 | */ |
1043 | rq->cmd_type = REQ_TYPE_SPECIAL; |
1044 | |
1045 | rq->special = data; |
1046 | |
1047 | spin_lock_irqsave(q->queue_lock, flags); |
1048 | |
1049 | /* |
1050 | * If command is tagged, release the tag |
1051 | */ |
1052 | if (blk_rq_tagged(rq)) |
1053 | blk_queue_end_tag(q, rq); |
1054 | |
1055 | drive_stat_acct(rq, 1); |
1056 | __elv_add_request(q, rq, where, 0); |
1057 | __blk_run_queue(q, false); |
1058 | spin_unlock_irqrestore(q->queue_lock, flags); |
1059 | } |
1060 | EXPORT_SYMBOL(blk_insert_request); |
1061 | |
1062 | static void part_round_stats_single(int cpu, struct hd_struct *part, |
1063 | unsigned long now) |
1064 | { |
1065 | if (now == part->stamp) |
1066 | return; |
1067 | |
1068 | if (part_in_flight(part)) { |
1069 | __part_stat_add(cpu, part, time_in_queue, |
1070 | part_in_flight(part) * (now - part->stamp)); |
1071 | __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); |
1072 | } |
1073 | part->stamp = now; |
1074 | } |
1075 | |
1076 | /** |
1077 | * part_round_stats() - Round off the performance stats on a struct disk_stats. |
1078 | * @cpu: cpu number for stats access |
1079 | * @part: target partition |
1080 | * |
1081 | * The average IO queue length and utilisation statistics are maintained |
1082 | * by observing the current state of the queue length and the amount of |
1083 | * time it has been in this state for. |
1084 | * |
1085 | * Normally, that accounting is done on IO completion, but that can result |
1086 | * in more than a second's worth of IO being accounted for within any one |
1087 | * second, leading to >100% utilisation. To deal with that, we call this |
1088 | * function to do a round-off before returning the results when reading |
1089 | * /proc/diskstats. This accounts immediately for all queue usage up to |
1090 | * the current jiffies and restarts the counters again. |
1091 | */ |
1092 | void part_round_stats(int cpu, struct hd_struct *part) |
1093 | { |
1094 | unsigned long now = jiffies; |
1095 | |
1096 | if (part->partno) |
1097 | part_round_stats_single(cpu, &part_to_disk(part)->part0, now); |
1098 | part_round_stats_single(cpu, part, now); |
1099 | } |
1100 | EXPORT_SYMBOL_GPL(part_round_stats); |
1101 | |
1102 | /* |
1103 | * queue lock must be held |
1104 | */ |
1105 | void __blk_put_request(struct request_queue *q, struct request *req) |
1106 | { |
1107 | if (unlikely(!q)) |
1108 | return; |
1109 | if (unlikely(--req->ref_count)) |
1110 | return; |
1111 | |
1112 | elv_completed_request(q, req); |
1113 | |
1114 | /* this is a bio leak */ |
1115 | WARN_ON(req->bio != NULL); |
1116 | |
1117 | /* |
1118 | * Request may not have originated from ll_rw_blk. if not, |
1119 | * it didn't come out of our reserved rq pools |
1120 | */ |
1121 | if (req->cmd_flags & REQ_ALLOCED) { |
1122 | int is_sync = rq_is_sync(req) != 0; |
1123 | int priv = req->cmd_flags & REQ_ELVPRIV; |
1124 | |
1125 | BUG_ON(!list_empty(&req->queuelist)); |
1126 | BUG_ON(!hlist_unhashed(&req->hash)); |
1127 | |
1128 | blk_free_request(q, req); |
1129 | freed_request(q, is_sync, priv); |
1130 | } |
1131 | } |
1132 | EXPORT_SYMBOL_GPL(__blk_put_request); |
1133 | |
1134 | void blk_put_request(struct request *req) |
1135 | { |
1136 | unsigned long flags; |
1137 | struct request_queue *q = req->q; |
1138 | |
1139 | spin_lock_irqsave(q->queue_lock, flags); |
1140 | __blk_put_request(q, req); |
1141 | spin_unlock_irqrestore(q->queue_lock, flags); |
1142 | } |
1143 | EXPORT_SYMBOL(blk_put_request); |
1144 | |
1145 | /** |
1146 | * blk_add_request_payload - add a payload to a request |
1147 | * @rq: request to update |
1148 | * @page: page backing the payload |
1149 | * @len: length of the payload. |
1150 | * |
1151 | * This allows to later add a payload to an already submitted request by |
1152 | * a block driver. The driver needs to take care of freeing the payload |
1153 | * itself. |
1154 | * |
1155 | * Note that this is a quite horrible hack and nothing but handling of |
1156 | * discard requests should ever use it. |
1157 | */ |
1158 | void blk_add_request_payload(struct request *rq, struct page *page, |
1159 | unsigned int len) |
1160 | { |
1161 | struct bio *bio = rq->bio; |
1162 | |
1163 | bio->bi_io_vec->bv_page = page; |
1164 | bio->bi_io_vec->bv_offset = 0; |
1165 | bio->bi_io_vec->bv_len = len; |
1166 | |
1167 | bio->bi_size = len; |
1168 | bio->bi_vcnt = 1; |
1169 | bio->bi_phys_segments = 1; |
1170 | |
1171 | rq->__data_len = rq->resid_len = len; |
1172 | rq->nr_phys_segments = 1; |
1173 | rq->buffer = bio_data(bio); |
1174 | } |
1175 | EXPORT_SYMBOL_GPL(blk_add_request_payload); |
1176 | |
1177 | void init_request_from_bio(struct request *req, struct bio *bio) |
1178 | { |
1179 | req->cpu = bio->bi_comp_cpu; |
1180 | req->cmd_type = REQ_TYPE_FS; |
1181 | |
1182 | req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK; |
1183 | if (bio->bi_rw & REQ_RAHEAD) |
1184 | req->cmd_flags |= REQ_FAILFAST_MASK; |
1185 | |
1186 | req->errors = 0; |
1187 | req->__sector = bio->bi_sector; |
1188 | req->ioprio = bio_prio(bio); |
1189 | blk_rq_bio_prep(req->q, req, bio); |
1190 | } |
1191 | |
1192 | /* |
1193 | * Only disabling plugging for non-rotational devices if it does tagging |
1194 | * as well, otherwise we do need the proper merging |
1195 | */ |
1196 | static inline bool queue_should_plug(struct request_queue *q) |
1197 | { |
1198 | return !(blk_queue_nonrot(q) && blk_queue_tagged(q)); |
1199 | } |
1200 | |
1201 | static int __make_request(struct request_queue *q, struct bio *bio) |
1202 | { |
1203 | struct request *req; |
1204 | int el_ret; |
1205 | unsigned int bytes = bio->bi_size; |
1206 | const unsigned short prio = bio_prio(bio); |
1207 | const bool sync = !!(bio->bi_rw & REQ_SYNC); |
1208 | const bool unplug = !!(bio->bi_rw & REQ_UNPLUG); |
1209 | const unsigned long ff = bio->bi_rw & REQ_FAILFAST_MASK; |
1210 | int where = ELEVATOR_INSERT_SORT; |
1211 | int rw_flags; |
1212 | |
1213 | /* |
1214 | * low level driver can indicate that it wants pages above a |
1215 | * certain limit bounced to low memory (ie for highmem, or even |
1216 | * ISA dma in theory) |
1217 | */ |
1218 | blk_queue_bounce(q, &bio); |
1219 | |
1220 | spin_lock_irq(q->queue_lock); |
1221 | |
1222 | if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { |
1223 | where = ELEVATOR_INSERT_FRONT; |
1224 | goto get_rq; |
1225 | } |
1226 | |
1227 | if (elv_queue_empty(q)) |
1228 | goto get_rq; |
1229 | |
1230 | el_ret = elv_merge(q, &req, bio); |
1231 | switch (el_ret) { |
1232 | case ELEVATOR_BACK_MERGE: |
1233 | BUG_ON(!rq_mergeable(req)); |
1234 | |
1235 | if (!ll_back_merge_fn(q, req, bio)) |
1236 | break; |
1237 | |
1238 | trace_block_bio_backmerge(q, bio); |
1239 | |
1240 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) |
1241 | blk_rq_set_mixed_merge(req); |
1242 | |
1243 | req->biotail->bi_next = bio; |
1244 | req->biotail = bio; |
1245 | req->__data_len += bytes; |
1246 | req->ioprio = ioprio_best(req->ioprio, prio); |
1247 | if (!blk_rq_cpu_valid(req)) |
1248 | req->cpu = bio->bi_comp_cpu; |
1249 | drive_stat_acct(req, 0); |
1250 | elv_bio_merged(q, req, bio); |
1251 | if (!attempt_back_merge(q, req)) |
1252 | elv_merged_request(q, req, el_ret); |
1253 | goto out; |
1254 | |
1255 | case ELEVATOR_FRONT_MERGE: |
1256 | BUG_ON(!rq_mergeable(req)); |
1257 | |
1258 | if (!ll_front_merge_fn(q, req, bio)) |
1259 | break; |
1260 | |
1261 | trace_block_bio_frontmerge(q, bio); |
1262 | |
1263 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) { |
1264 | blk_rq_set_mixed_merge(req); |
1265 | req->cmd_flags &= ~REQ_FAILFAST_MASK; |
1266 | req->cmd_flags |= ff; |
1267 | } |
1268 | |
1269 | bio->bi_next = req->bio; |
1270 | req->bio = bio; |
1271 | |
1272 | /* |
1273 | * may not be valid. if the low level driver said |
1274 | * it didn't need a bounce buffer then it better |
1275 | * not touch req->buffer either... |
1276 | */ |
1277 | req->buffer = bio_data(bio); |
1278 | req->__sector = bio->bi_sector; |
1279 | req->__data_len += bytes; |
1280 | req->ioprio = ioprio_best(req->ioprio, prio); |
1281 | if (!blk_rq_cpu_valid(req)) |
1282 | req->cpu = bio->bi_comp_cpu; |
1283 | drive_stat_acct(req, 0); |
1284 | elv_bio_merged(q, req, bio); |
1285 | if (!attempt_front_merge(q, req)) |
1286 | elv_merged_request(q, req, el_ret); |
1287 | goto out; |
1288 | |
1289 | /* ELV_NO_MERGE: elevator says don't/can't merge. */ |
1290 | default: |
1291 | ; |
1292 | } |
1293 | |
1294 | get_rq: |
1295 | /* |
1296 | * This sync check and mask will be re-done in init_request_from_bio(), |
1297 | * but we need to set it earlier to expose the sync flag to the |
1298 | * rq allocator and io schedulers. |
1299 | */ |
1300 | rw_flags = bio_data_dir(bio); |
1301 | if (sync) |
1302 | rw_flags |= REQ_SYNC; |
1303 | |
1304 | /* |
1305 | * Grab a free request. This is might sleep but can not fail. |
1306 | * Returns with the queue unlocked. |
1307 | */ |
1308 | req = get_request_wait(q, rw_flags, bio); |
1309 | |
1310 | /* |
1311 | * After dropping the lock and possibly sleeping here, our request |
1312 | * may now be mergeable after it had proven unmergeable (above). |
1313 | * We don't worry about that case for efficiency. It won't happen |
1314 | * often, and the elevators are able to handle it. |
1315 | */ |
1316 | init_request_from_bio(req, bio); |
1317 | |
1318 | spin_lock_irq(q->queue_lock); |
1319 | if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) || |
1320 | bio_flagged(bio, BIO_CPU_AFFINE)) |
1321 | req->cpu = blk_cpu_to_group(smp_processor_id()); |
1322 | if (queue_should_plug(q) && elv_queue_empty(q)) |
1323 | blk_plug_device(q); |
1324 | |
1325 | /* insert the request into the elevator */ |
1326 | drive_stat_acct(req, 1); |
1327 | __elv_add_request(q, req, where, 0); |
1328 | out: |
1329 | if (unplug || !queue_should_plug(q)) |
1330 | __generic_unplug_device(q); |
1331 | spin_unlock_irq(q->queue_lock); |
1332 | return 0; |
1333 | } |
1334 | |
1335 | /* |
1336 | * If bio->bi_dev is a partition, remap the location |
1337 | */ |
1338 | static inline void blk_partition_remap(struct bio *bio) |
1339 | { |
1340 | struct block_device *bdev = bio->bi_bdev; |
1341 | |
1342 | if (bio_sectors(bio) && bdev != bdev->bd_contains) { |
1343 | struct hd_struct *p = bdev->bd_part; |
1344 | |
1345 | bio->bi_sector += p->start_sect; |
1346 | bio->bi_bdev = bdev->bd_contains; |
1347 | |
1348 | trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio, |
1349 | bdev->bd_dev, |
1350 | bio->bi_sector - p->start_sect); |
1351 | } |
1352 | } |
1353 | |
1354 | static void handle_bad_sector(struct bio *bio) |
1355 | { |
1356 | char b[BDEVNAME_SIZE]; |
1357 | |
1358 | printk(KERN_INFO "attempt to access beyond end of device\n"); |
1359 | printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", |
1360 | bdevname(bio->bi_bdev, b), |
1361 | bio->bi_rw, |
1362 | (unsigned long long)bio->bi_sector + bio_sectors(bio), |
1363 | (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9)); |
1364 | |
1365 | set_bit(BIO_EOF, &bio->bi_flags); |
1366 | } |
1367 | |
1368 | #ifdef CONFIG_FAIL_MAKE_REQUEST |
1369 | |
1370 | static DECLARE_FAULT_ATTR(fail_make_request); |
1371 | |
1372 | static int __init setup_fail_make_request(char *str) |
1373 | { |
1374 | return setup_fault_attr(&fail_make_request, str); |
1375 | } |
1376 | __setup("fail_make_request=", setup_fail_make_request); |
1377 | |
1378 | static int should_fail_request(struct bio *bio) |
1379 | { |
1380 | struct hd_struct *part = bio->bi_bdev->bd_part; |
1381 | |
1382 | if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail) |
1383 | return should_fail(&fail_make_request, bio->bi_size); |
1384 | |
1385 | return 0; |
1386 | } |
1387 | |
1388 | static int __init fail_make_request_debugfs(void) |
1389 | { |
1390 | return init_fault_attr_dentries(&fail_make_request, |
1391 | "fail_make_request"); |
1392 | } |
1393 | |
1394 | late_initcall(fail_make_request_debugfs); |
1395 | |
1396 | #else /* CONFIG_FAIL_MAKE_REQUEST */ |
1397 | |
1398 | static inline int should_fail_request(struct bio *bio) |
1399 | { |
1400 | return 0; |
1401 | } |
1402 | |
1403 | #endif /* CONFIG_FAIL_MAKE_REQUEST */ |
1404 | |
1405 | /* |
1406 | * Check whether this bio extends beyond the end of the device. |
1407 | */ |
1408 | static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) |
1409 | { |
1410 | sector_t maxsector; |
1411 | |
1412 | if (!nr_sectors) |
1413 | return 0; |
1414 | |
1415 | /* Test device or partition size, when known. */ |
1416 | maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; |
1417 | if (maxsector) { |
1418 | sector_t sector = bio->bi_sector; |
1419 | |
1420 | if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { |
1421 | /* |
1422 | * This may well happen - the kernel calls bread() |
1423 | * without checking the size of the device, e.g., when |
1424 | * mounting a device. |
1425 | */ |
1426 | handle_bad_sector(bio); |
1427 | return 1; |
1428 | } |
1429 | } |
1430 | |
1431 | return 0; |
1432 | } |
1433 | |
1434 | /** |
1435 | * generic_make_request - hand a buffer to its device driver for I/O |
1436 | * @bio: The bio describing the location in memory and on the device. |
1437 | * |
1438 | * generic_make_request() is used to make I/O requests of block |
1439 | * devices. It is passed a &struct bio, which describes the I/O that needs |
1440 | * to be done. |
1441 | * |
1442 | * generic_make_request() does not return any status. The |
1443 | * success/failure status of the request, along with notification of |
1444 | * completion, is delivered asynchronously through the bio->bi_end_io |
1445 | * function described (one day) else where. |
1446 | * |
1447 | * The caller of generic_make_request must make sure that bi_io_vec |
1448 | * are set to describe the memory buffer, and that bi_dev and bi_sector are |
1449 | * set to describe the device address, and the |
1450 | * bi_end_io and optionally bi_private are set to describe how |
1451 | * completion notification should be signaled. |
1452 | * |
1453 | * generic_make_request and the drivers it calls may use bi_next if this |
1454 | * bio happens to be merged with someone else, and may change bi_dev and |
1455 | * bi_sector for remaps as it sees fit. So the values of these fields |
1456 | * should NOT be depended on after the call to generic_make_request. |
1457 | */ |
1458 | static inline void __generic_make_request(struct bio *bio) |
1459 | { |
1460 | struct request_queue *q; |
1461 | sector_t old_sector; |
1462 | int ret, nr_sectors = bio_sectors(bio); |
1463 | dev_t old_dev; |
1464 | int err = -EIO; |
1465 | |
1466 | might_sleep(); |
1467 | |
1468 | if (bio_check_eod(bio, nr_sectors)) |
1469 | goto end_io; |
1470 | |
1471 | /* |
1472 | * Resolve the mapping until finished. (drivers are |
1473 | * still free to implement/resolve their own stacking |
1474 | * by explicitly returning 0) |
1475 | * |
1476 | * NOTE: we don't repeat the blk_size check for each new device. |
1477 | * Stacking drivers are expected to know what they are doing. |
1478 | */ |
1479 | old_sector = -1; |
1480 | old_dev = 0; |
1481 | do { |
1482 | char b[BDEVNAME_SIZE]; |
1483 | |
1484 | q = bdev_get_queue(bio->bi_bdev); |
1485 | if (unlikely(!q)) { |
1486 | printk(KERN_ERR |
1487 | "generic_make_request: Trying to access " |
1488 | "nonexistent block-device %s (%Lu)\n", |
1489 | bdevname(bio->bi_bdev, b), |
1490 | (long long) bio->bi_sector); |
1491 | goto end_io; |
1492 | } |
1493 | |
1494 | if (unlikely(!(bio->bi_rw & REQ_DISCARD) && |
1495 | nr_sectors > queue_max_hw_sectors(q))) { |
1496 | printk(KERN_ERR "bio too big device %s (%u > %u)\n", |
1497 | bdevname(bio->bi_bdev, b), |
1498 | bio_sectors(bio), |
1499 | queue_max_hw_sectors(q)); |
1500 | goto end_io; |
1501 | } |
1502 | |
1503 | if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) |
1504 | goto end_io; |
1505 | |
1506 | if (should_fail_request(bio)) |
1507 | goto end_io; |
1508 | |
1509 | /* |
1510 | * If this device has partitions, remap block n |
1511 | * of partition p to block n+start(p) of the disk. |
1512 | */ |
1513 | blk_partition_remap(bio); |
1514 | |
1515 | if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) |
1516 | goto end_io; |
1517 | |
1518 | if (old_sector != -1) |
1519 | trace_block_bio_remap(q, bio, old_dev, old_sector); |
1520 | |
1521 | old_sector = bio->bi_sector; |
1522 | old_dev = bio->bi_bdev->bd_dev; |
1523 | |
1524 | if (bio_check_eod(bio, nr_sectors)) |
1525 | goto end_io; |
1526 | |
1527 | /* |
1528 | * Filter flush bio's early so that make_request based |
1529 | * drivers without flush support don't have to worry |
1530 | * about them. |
1531 | */ |
1532 | if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) { |
1533 | bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA); |
1534 | if (!nr_sectors) { |
1535 | err = 0; |
1536 | goto end_io; |
1537 | } |
1538 | } |
1539 | |
1540 | if ((bio->bi_rw & REQ_DISCARD) && |
1541 | (!blk_queue_discard(q) || |
1542 | ((bio->bi_rw & REQ_SECURE) && |
1543 | !blk_queue_secdiscard(q)))) { |
1544 | err = -EOPNOTSUPP; |
1545 | goto end_io; |
1546 | } |
1547 | |
1548 | blk_throtl_bio(q, &bio); |
1549 | |
1550 | /* |
1551 | * If bio = NULL, bio has been throttled and will be submitted |
1552 | * later. |
1553 | */ |
1554 | if (!bio) |
1555 | break; |
1556 | |
1557 | trace_block_bio_queue(q, bio); |
1558 | |
1559 | ret = q->make_request_fn(q, bio); |
1560 | } while (ret); |
1561 | |
1562 | return; |
1563 | |
1564 | end_io: |
1565 | bio_endio(bio, err); |
1566 | } |
1567 | |
1568 | /* |
1569 | * We only want one ->make_request_fn to be active at a time, |
1570 | * else stack usage with stacked devices could be a problem. |
1571 | * So use current->bio_list to keep a list of requests |
1572 | * submited by a make_request_fn function. |
1573 | * current->bio_list is also used as a flag to say if |
1574 | * generic_make_request is currently active in this task or not. |
1575 | * If it is NULL, then no make_request is active. If it is non-NULL, |
1576 | * then a make_request is active, and new requests should be added |
1577 | * at the tail |
1578 | */ |
1579 | void generic_make_request(struct bio *bio) |
1580 | { |
1581 | struct bio_list bio_list_on_stack; |
1582 | |
1583 | if (current->bio_list) { |
1584 | /* make_request is active */ |
1585 | bio_list_add(current->bio_list, bio); |
1586 | return; |
1587 | } |
1588 | /* following loop may be a bit non-obvious, and so deserves some |
1589 | * explanation. |
1590 | * Before entering the loop, bio->bi_next is NULL (as all callers |
1591 | * ensure that) so we have a list with a single bio. |
1592 | * We pretend that we have just taken it off a longer list, so |
1593 | * we assign bio_list to a pointer to the bio_list_on_stack, |
1594 | * thus initialising the bio_list of new bios to be |
1595 | * added. __generic_make_request may indeed add some more bios |
1596 | * through a recursive call to generic_make_request. If it |
1597 | * did, we find a non-NULL value in bio_list and re-enter the loop |
1598 | * from the top. In this case we really did just take the bio |
1599 | * of the top of the list (no pretending) and so remove it from |
1600 | * bio_list, and call into __generic_make_request again. |
1601 | * |
1602 | * The loop was structured like this to make only one call to |
1603 | * __generic_make_request (which is important as it is large and |
1604 | * inlined) and to keep the structure simple. |
1605 | */ |
1606 | BUG_ON(bio->bi_next); |
1607 | bio_list_init(&bio_list_on_stack); |
1608 | current->bio_list = &bio_list_on_stack; |
1609 | do { |
1610 | __generic_make_request(bio); |
1611 | bio = bio_list_pop(current->bio_list); |
1612 | } while (bio); |
1613 | current->bio_list = NULL; /* deactivate */ |
1614 | } |
1615 | EXPORT_SYMBOL(generic_make_request); |
1616 | |
1617 | /** |
1618 | * submit_bio - submit a bio to the block device layer for I/O |
1619 | * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) |
1620 | * @bio: The &struct bio which describes the I/O |
1621 | * |
1622 | * submit_bio() is very similar in purpose to generic_make_request(), and |
1623 | * uses that function to do most of the work. Both are fairly rough |
1624 | * interfaces; @bio must be presetup and ready for I/O. |
1625 | * |
1626 | */ |
1627 | void submit_bio(int rw, struct bio *bio) |
1628 | { |
1629 | int count = bio_sectors(bio); |
1630 | |
1631 | bio->bi_rw |= rw; |
1632 | |
1633 | /* |
1634 | * If it's a regular read/write or a barrier with data attached, |
1635 | * go through the normal accounting stuff before submission. |
1636 | */ |
1637 | if (bio_has_data(bio) && !(rw & REQ_DISCARD)) { |
1638 | if (rw & WRITE) { |
1639 | count_vm_events(PGPGOUT, count); |
1640 | } else { |
1641 | task_io_account_read(bio->bi_size); |
1642 | count_vm_events(PGPGIN, count); |
1643 | } |
1644 | |
1645 | if (unlikely(block_dump)) { |
1646 | char b[BDEVNAME_SIZE]; |
1647 | printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", |
1648 | current->comm, task_pid_nr(current), |
1649 | (rw & WRITE) ? "WRITE" : "READ", |
1650 | (unsigned long long)bio->bi_sector, |
1651 | bdevname(bio->bi_bdev, b), |
1652 | count); |
1653 | } |
1654 | } |
1655 | |
1656 | generic_make_request(bio); |
1657 | } |
1658 | EXPORT_SYMBOL(submit_bio); |
1659 | |
1660 | /** |
1661 | * blk_rq_check_limits - Helper function to check a request for the queue limit |
1662 | * @q: the queue |
1663 | * @rq: the request being checked |
1664 | * |
1665 | * Description: |
1666 | * @rq may have been made based on weaker limitations of upper-level queues |
1667 | * in request stacking drivers, and it may violate the limitation of @q. |
1668 | * Since the block layer and the underlying device driver trust @rq |
1669 | * after it is inserted to @q, it should be checked against @q before |
1670 | * the insertion using this generic function. |
1671 | * |
1672 | * This function should also be useful for request stacking drivers |
1673 | * in some cases below, so export this function. |
1674 | * Request stacking drivers like request-based dm may change the queue |
1675 | * limits while requests are in the queue (e.g. dm's table swapping). |
1676 | * Such request stacking drivers should check those requests agaist |
1677 | * the new queue limits again when they dispatch those requests, |
1678 | * although such checkings are also done against the old queue limits |
1679 | * when submitting requests. |
1680 | */ |
1681 | int blk_rq_check_limits(struct request_queue *q, struct request *rq) |
1682 | { |
1683 | if (rq->cmd_flags & REQ_DISCARD) |
1684 | return 0; |
1685 | |
1686 | if (blk_rq_sectors(rq) > queue_max_sectors(q) || |
1687 | blk_rq_bytes(rq) > queue_max_hw_sectors(q) << 9) { |
1688 | printk(KERN_ERR "%s: over max size limit.\n", __func__); |
1689 | return -EIO; |
1690 | } |
1691 | |
1692 | /* |
1693 | * queue's settings related to segment counting like q->bounce_pfn |
1694 | * may differ from that of other stacking queues. |
1695 | * Recalculate it to check the request correctly on this queue's |
1696 | * limitation. |
1697 | */ |
1698 | blk_recalc_rq_segments(rq); |
1699 | if (rq->nr_phys_segments > queue_max_segments(q)) { |
1700 | printk(KERN_ERR "%s: over max segments limit.\n", __func__); |
1701 | return -EIO; |
1702 | } |
1703 | |
1704 | return 0; |
1705 | } |
1706 | EXPORT_SYMBOL_GPL(blk_rq_check_limits); |
1707 | |
1708 | /** |
1709 | * blk_insert_cloned_request - Helper for stacking drivers to submit a request |
1710 | * @q: the queue to submit the request |
1711 | * @rq: the request being queued |
1712 | */ |
1713 | int blk_insert_cloned_request(struct request_queue *q, struct request *rq) |
1714 | { |
1715 | unsigned long flags; |
1716 | |
1717 | if (blk_rq_check_limits(q, rq)) |
1718 | return -EIO; |
1719 | |
1720 | #ifdef CONFIG_FAIL_MAKE_REQUEST |
1721 | if (rq->rq_disk && rq->rq_disk->part0.make_it_fail && |
1722 | should_fail(&fail_make_request, blk_rq_bytes(rq))) |
1723 | return -EIO; |
1724 | #endif |
1725 | |
1726 | spin_lock_irqsave(q->queue_lock, flags); |
1727 | |
1728 | /* |
1729 | * Submitting request must be dequeued before calling this function |
1730 | * because it will be linked to another request_queue |
1731 | */ |
1732 | BUG_ON(blk_queued_rq(rq)); |
1733 | |
1734 | drive_stat_acct(rq, 1); |
1735 | __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); |
1736 | |
1737 | spin_unlock_irqrestore(q->queue_lock, flags); |
1738 | |
1739 | return 0; |
1740 | } |
1741 | EXPORT_SYMBOL_GPL(blk_insert_cloned_request); |
1742 | |
1743 | /** |
1744 | * blk_rq_err_bytes - determine number of bytes till the next failure boundary |
1745 | * @rq: request to examine |
1746 | * |
1747 | * Description: |
1748 | * A request could be merge of IOs which require different failure |
1749 | * handling. This function determines the number of bytes which |
1750 | * can be failed from the beginning of the request without |
1751 | * crossing into area which need to be retried further. |
1752 | * |
1753 | * Return: |
1754 | * The number of bytes to fail. |
1755 | * |
1756 | * Context: |
1757 | * queue_lock must be held. |
1758 | */ |
1759 | unsigned int blk_rq_err_bytes(const struct request *rq) |
1760 | { |
1761 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; |
1762 | unsigned int bytes = 0; |
1763 | struct bio *bio; |
1764 | |
1765 | if (!(rq->cmd_flags & REQ_MIXED_MERGE)) |
1766 | return blk_rq_bytes(rq); |
1767 | |
1768 | /* |
1769 | * Currently the only 'mixing' which can happen is between |
1770 | * different fastfail types. We can safely fail portions |
1771 | * which have all the failfast bits that the first one has - |
1772 | * the ones which are at least as eager to fail as the first |
1773 | * one. |
1774 | */ |
1775 | for (bio = rq->bio; bio; bio = bio->bi_next) { |
1776 | if ((bio->bi_rw & ff) != ff) |
1777 | break; |
1778 | bytes += bio->bi_size; |
1779 | } |
1780 | |
1781 | /* this could lead to infinite loop */ |
1782 | BUG_ON(blk_rq_bytes(rq) && !bytes); |
1783 | return bytes; |
1784 | } |
1785 | EXPORT_SYMBOL_GPL(blk_rq_err_bytes); |
1786 | |
1787 | static void blk_account_io_completion(struct request *req, unsigned int bytes) |
1788 | { |
1789 | if (blk_do_io_stat(req)) { |
1790 | const int rw = rq_data_dir(req); |
1791 | struct hd_struct *part; |
1792 | int cpu; |
1793 | |
1794 | cpu = part_stat_lock(); |
1795 | part = req->part; |
1796 | part_stat_add(cpu, part, sectors[rw], bytes >> 9); |
1797 | part_stat_unlock(); |
1798 | } |
1799 | } |
1800 | |
1801 | static void blk_account_io_done(struct request *req) |
1802 | { |
1803 | /* |
1804 | * Account IO completion. flush_rq isn't accounted as a |
1805 | * normal IO on queueing nor completion. Accounting the |
1806 | * containing request is enough. |
1807 | */ |
1808 | if (blk_do_io_stat(req) && req != &req->q->flush_rq) { |
1809 | unsigned long duration = jiffies - req->start_time; |
1810 | const int rw = rq_data_dir(req); |
1811 | struct hd_struct *part; |
1812 | int cpu; |
1813 | |
1814 | cpu = part_stat_lock(); |
1815 | part = req->part; |
1816 | |
1817 | part_stat_inc(cpu, part, ios[rw]); |
1818 | part_stat_add(cpu, part, ticks[rw], duration); |
1819 | part_round_stats(cpu, part); |
1820 | part_dec_in_flight(part, rw); |
1821 | |
1822 | hd_struct_put(part); |
1823 | part_stat_unlock(); |
1824 | } |
1825 | } |
1826 | |
1827 | /** |
1828 | * blk_peek_request - peek at the top of a request queue |
1829 | * @q: request queue to peek at |
1830 | * |
1831 | * Description: |
1832 | * Return the request at the top of @q. The returned request |
1833 | * should be started using blk_start_request() before LLD starts |
1834 | * processing it. |
1835 | * |
1836 | * Return: |
1837 | * Pointer to the request at the top of @q if available. Null |
1838 | * otherwise. |
1839 | * |
1840 | * Context: |
1841 | * queue_lock must be held. |
1842 | */ |
1843 | struct request *blk_peek_request(struct request_queue *q) |
1844 | { |
1845 | struct request *rq; |
1846 | int ret; |
1847 | |
1848 | while ((rq = __elv_next_request(q)) != NULL) { |
1849 | if (!(rq->cmd_flags & REQ_STARTED)) { |
1850 | /* |
1851 | * This is the first time the device driver |
1852 | * sees this request (possibly after |
1853 | * requeueing). Notify IO scheduler. |
1854 | */ |
1855 | if (rq->cmd_flags & REQ_SORTED) |
1856 | elv_activate_rq(q, rq); |
1857 | |
1858 | /* |
1859 | * just mark as started even if we don't start |
1860 | * it, a request that has been delayed should |
1861 | * not be passed by new incoming requests |
1862 | */ |
1863 | rq->cmd_flags |= REQ_STARTED; |
1864 | trace_block_rq_issue(q, rq); |
1865 | } |
1866 | |
1867 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1868 | q->end_sector = rq_end_sector(rq); |
1869 | q->boundary_rq = NULL; |
1870 | } |
1871 | |
1872 | if (rq->cmd_flags & REQ_DONTPREP) |
1873 | break; |
1874 | |
1875 | if (q->dma_drain_size && blk_rq_bytes(rq)) { |
1876 | /* |
1877 | * make sure space for the drain appears we |
1878 | * know we can do this because max_hw_segments |
1879 | * has been adjusted to be one fewer than the |
1880 | * device can handle |
1881 | */ |
1882 | rq->nr_phys_segments++; |
1883 | } |
1884 | |
1885 | if (!q->prep_rq_fn) |
1886 | break; |
1887 | |
1888 | ret = q->prep_rq_fn(q, rq); |
1889 | if (ret == BLKPREP_OK) { |
1890 | break; |
1891 | } else if (ret == BLKPREP_DEFER) { |
1892 | /* |
1893 | * the request may have been (partially) prepped. |
1894 | * we need to keep this request in the front to |
1895 | * avoid resource deadlock. REQ_STARTED will |
1896 | * prevent other fs requests from passing this one. |
1897 | */ |
1898 | if (q->dma_drain_size && blk_rq_bytes(rq) && |
1899 | !(rq->cmd_flags & REQ_DONTPREP)) { |
1900 | /* |
1901 | * remove the space for the drain we added |
1902 | * so that we don't add it again |
1903 | */ |
1904 | --rq->nr_phys_segments; |
1905 | } |
1906 | |
1907 | rq = NULL; |
1908 | break; |
1909 | } else if (ret == BLKPREP_KILL) { |
1910 | rq->cmd_flags |= REQ_QUIET; |
1911 | /* |
1912 | * Mark this request as started so we don't trigger |
1913 | * any debug logic in the end I/O path. |
1914 | */ |
1915 | blk_start_request(rq); |
1916 | __blk_end_request_all(rq, -EIO); |
1917 | } else { |
1918 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); |
1919 | break; |
1920 | } |
1921 | } |
1922 | |
1923 | return rq; |
1924 | } |
1925 | EXPORT_SYMBOL(blk_peek_request); |
1926 | |
1927 | void blk_dequeue_request(struct request *rq) |
1928 | { |
1929 | struct request_queue *q = rq->q; |
1930 | |
1931 | BUG_ON(list_empty(&rq->queuelist)); |
1932 | BUG_ON(ELV_ON_HASH(rq)); |
1933 | |
1934 | list_del_init(&rq->queuelist); |
1935 | |
1936 | /* |
1937 | * the time frame between a request being removed from the lists |
1938 | * and to it is freed is accounted as io that is in progress at |
1939 | * the driver side. |
1940 | */ |
1941 | if (blk_account_rq(rq)) { |
1942 | q->in_flight[rq_is_sync(rq)]++; |
1943 | set_io_start_time_ns(rq); |
1944 | } |
1945 | } |
1946 | |
1947 | /** |
1948 | * blk_start_request - start request processing on the driver |
1949 | * @req: request to dequeue |
1950 | * |
1951 | * Description: |
1952 | * Dequeue @req and start timeout timer on it. This hands off the |
1953 | * request to the driver. |
1954 | * |
1955 | * Block internal functions which don't want to start timer should |
1956 | * call blk_dequeue_request(). |
1957 | * |
1958 | * Context: |
1959 | * queue_lock must be held. |
1960 | */ |
1961 | void blk_start_request(struct request *req) |
1962 | { |
1963 | blk_dequeue_request(req); |
1964 | |
1965 | /* |
1966 | * We are now handing the request to the hardware, initialize |
1967 | * resid_len to full count and add the timeout handler. |
1968 | */ |
1969 | req->resid_len = blk_rq_bytes(req); |
1970 | if (unlikely(blk_bidi_rq(req))) |
1971 | req->next_rq->resid_len = blk_rq_bytes(req->next_rq); |
1972 | |
1973 | blk_add_timer(req); |
1974 | } |
1975 | EXPORT_SYMBOL(blk_start_request); |
1976 | |
1977 | /** |
1978 | * blk_fetch_request - fetch a request from a request queue |
1979 | * @q: request queue to fetch a request from |
1980 | * |
1981 | * Description: |
1982 | * Return the request at the top of @q. The request is started on |
1983 | * return and LLD can start processing it immediately. |
1984 | * |
1985 | * Return: |
1986 | * Pointer to the request at the top of @q if available. Null |
1987 | * otherwise. |
1988 | * |
1989 | * Context: |
1990 | * queue_lock must be held. |
1991 | */ |
1992 | struct request *blk_fetch_request(struct request_queue *q) |
1993 | { |
1994 | struct request *rq; |
1995 | |
1996 | rq = blk_peek_request(q); |
1997 | if (rq) |
1998 | blk_start_request(rq); |
1999 | return rq; |
2000 | } |
2001 | EXPORT_SYMBOL(blk_fetch_request); |
2002 | |
2003 | /** |
2004 | * blk_update_request - Special helper function for request stacking drivers |
2005 | * @req: the request being processed |
2006 | * @error: %0 for success, < %0 for error |
2007 | * @nr_bytes: number of bytes to complete @req |
2008 | * |
2009 | * Description: |
2010 | * Ends I/O on a number of bytes attached to @req, but doesn't complete |
2011 | * the request structure even if @req doesn't have leftover. |
2012 | * If @req has leftover, sets it up for the next range of segments. |
2013 | * |
2014 | * This special helper function is only for request stacking drivers |
2015 | * (e.g. request-based dm) so that they can handle partial completion. |
2016 | * Actual device drivers should use blk_end_request instead. |
2017 | * |
2018 | * Passing the result of blk_rq_bytes() as @nr_bytes guarantees |
2019 | * %false return from this function. |
2020 | * |
2021 | * Return: |
2022 | * %false - this request doesn't have any more data |
2023 | * %true - this request has more data |
2024 | **/ |
2025 | bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) |
2026 | { |
2027 | int total_bytes, bio_nbytes, next_idx = 0; |
2028 | struct bio *bio; |
2029 | |
2030 | if (!req->bio) |
2031 | return false; |
2032 | |
2033 | trace_block_rq_complete(req->q, req); |
2034 | |
2035 | /* |
2036 | * For fs requests, rq is just carrier of independent bio's |
2037 | * and each partial completion should be handled separately. |
2038 | * Reset per-request error on each partial completion. |
2039 | * |
2040 | * TODO: tj: This is too subtle. It would be better to let |
2041 | * low level drivers do what they see fit. |
2042 | */ |
2043 | if (req->cmd_type == REQ_TYPE_FS) |
2044 | req->errors = 0; |
2045 | |
2046 | if (error && req->cmd_type == REQ_TYPE_FS && |
2047 | !(req->cmd_flags & REQ_QUIET)) { |
2048 | printk(KERN_ERR "end_request: I/O error, dev %s, sector %llu\n", |
2049 | req->rq_disk ? req->rq_disk->disk_name : "?", |
2050 | (unsigned long long)blk_rq_pos(req)); |
2051 | } |
2052 | |
2053 | blk_account_io_completion(req, nr_bytes); |
2054 | |
2055 | total_bytes = bio_nbytes = 0; |
2056 | while ((bio = req->bio) != NULL) { |
2057 | int nbytes; |
2058 | |
2059 | if (nr_bytes >= bio->bi_size) { |
2060 | req->bio = bio->bi_next; |
2061 | nbytes = bio->bi_size; |
2062 | req_bio_endio(req, bio, nbytes, error); |
2063 | next_idx = 0; |
2064 | bio_nbytes = 0; |
2065 | } else { |
2066 | int idx = bio->bi_idx + next_idx; |
2067 | |
2068 | if (unlikely(idx >= bio->bi_vcnt)) { |
2069 | blk_dump_rq_flags(req, "__end_that"); |
2070 | printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n", |
2071 | __func__, idx, bio->bi_vcnt); |
2072 | break; |
2073 | } |
2074 | |
2075 | nbytes = bio_iovec_idx(bio, idx)->bv_len; |
2076 | BIO_BUG_ON(nbytes > bio->bi_size); |
2077 | |
2078 | /* |
2079 | * not a complete bvec done |
2080 | */ |
2081 | if (unlikely(nbytes > nr_bytes)) { |
2082 | bio_nbytes += nr_bytes; |
2083 | total_bytes += nr_bytes; |
2084 | break; |
2085 | } |
2086 | |
2087 | /* |
2088 | * advance to the next vector |
2089 | */ |
2090 | next_idx++; |
2091 | bio_nbytes += nbytes; |
2092 | } |
2093 | |
2094 | total_bytes += nbytes; |
2095 | nr_bytes -= nbytes; |
2096 | |
2097 | bio = req->bio; |
2098 | if (bio) { |
2099 | /* |
2100 | * end more in this run, or just return 'not-done' |
2101 | */ |
2102 | if (unlikely(nr_bytes <= 0)) |
2103 | break; |
2104 | } |
2105 | } |
2106 | |
2107 | /* |
2108 | * completely done |
2109 | */ |
2110 | if (!req->bio) { |
2111 | /* |
2112 | * Reset counters so that the request stacking driver |
2113 | * can find how many bytes remain in the request |
2114 | * later. |
2115 | */ |
2116 | req->__data_len = 0; |
2117 | return false; |
2118 | } |
2119 | |
2120 | /* |
2121 | * if the request wasn't completed, update state |
2122 | */ |
2123 | if (bio_nbytes) { |
2124 | req_bio_endio(req, bio, bio_nbytes, error); |
2125 | bio->bi_idx += next_idx; |
2126 | bio_iovec(bio)->bv_offset += nr_bytes; |
2127 | bio_iovec(bio)->bv_len -= nr_bytes; |
2128 | } |
2129 | |
2130 | req->__data_len -= total_bytes; |
2131 | req->buffer = bio_data(req->bio); |
2132 | |
2133 | /* update sector only for requests with clear definition of sector */ |
2134 | if (req->cmd_type == REQ_TYPE_FS || (req->cmd_flags & REQ_DISCARD)) |
2135 | req->__sector += total_bytes >> 9; |
2136 | |
2137 | /* mixed attributes always follow the first bio */ |
2138 | if (req->cmd_flags & REQ_MIXED_MERGE) { |
2139 | req->cmd_flags &= ~REQ_FAILFAST_MASK; |
2140 | req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK; |
2141 | } |
2142 | |
2143 | /* |
2144 | * If total number of sectors is less than the first segment |
2145 | * size, something has gone terribly wrong. |
2146 | */ |
2147 | if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { |
2148 | printk(KERN_ERR "blk: request botched\n"); |
2149 | req->__data_len = blk_rq_cur_bytes(req); |
2150 | } |
2151 | |
2152 | /* recalculate the number of segments */ |
2153 | blk_recalc_rq_segments(req); |
2154 | |
2155 | return true; |
2156 | } |
2157 | EXPORT_SYMBOL_GPL(blk_update_request); |
2158 | |
2159 | static bool blk_update_bidi_request(struct request *rq, int error, |
2160 | unsigned int nr_bytes, |
2161 | unsigned int bidi_bytes) |
2162 | { |
2163 | if (blk_update_request(rq, error, nr_bytes)) |
2164 | return true; |
2165 | |
2166 | /* Bidi request must be completed as a whole */ |
2167 | if (unlikely(blk_bidi_rq(rq)) && |
2168 | blk_update_request(rq->next_rq, error, bidi_bytes)) |
2169 | return true; |
2170 | |
2171 | if (blk_queue_add_random(rq->q)) |
2172 | add_disk_randomness(rq->rq_disk); |
2173 | |
2174 | return false; |
2175 | } |
2176 | |
2177 | /** |
2178 | * blk_unprep_request - unprepare a request |
2179 | * @req: the request |
2180 | * |
2181 | * This function makes a request ready for complete resubmission (or |
2182 | * completion). It happens only after all error handling is complete, |
2183 | * so represents the appropriate moment to deallocate any resources |
2184 | * that were allocated to the request in the prep_rq_fn. The queue |
2185 | * lock is held when calling this. |
2186 | */ |
2187 | void blk_unprep_request(struct request *req) |
2188 | { |
2189 | struct request_queue *q = req->q; |
2190 | |
2191 | req->cmd_flags &= ~REQ_DONTPREP; |
2192 | if (q->unprep_rq_fn) |
2193 | q->unprep_rq_fn(q, req); |
2194 | } |
2195 | EXPORT_SYMBOL_GPL(blk_unprep_request); |
2196 | |
2197 | /* |
2198 | * queue lock must be held |
2199 | */ |
2200 | static void blk_finish_request(struct request *req, int error) |
2201 | { |
2202 | if (blk_rq_tagged(req)) |
2203 | blk_queue_end_tag(req->q, req); |
2204 | |
2205 | BUG_ON(blk_queued_rq(req)); |
2206 | |
2207 | if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS) |
2208 | laptop_io_completion(&req->q->backing_dev_info); |
2209 | |
2210 | blk_delete_timer(req); |
2211 | |
2212 | if (req->cmd_flags & REQ_DONTPREP) |
2213 | blk_unprep_request(req); |
2214 | |
2215 | |
2216 | blk_account_io_done(req); |
2217 | |
2218 | if (req->end_io) |
2219 | req->end_io(req, error); |
2220 | else { |
2221 | if (blk_bidi_rq(req)) |
2222 | __blk_put_request(req->next_rq->q, req->next_rq); |
2223 | |
2224 | __blk_put_request(req->q, req); |
2225 | } |
2226 | } |
2227 | |
2228 | /** |
2229 | * blk_end_bidi_request - Complete a bidi request |
2230 | * @rq: the request to complete |
2231 | * @error: %0 for success, < %0 for error |
2232 | * @nr_bytes: number of bytes to complete @rq |
2233 | * @bidi_bytes: number of bytes to complete @rq->next_rq |
2234 | * |
2235 | * Description: |
2236 | * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. |
2237 | * Drivers that supports bidi can safely call this member for any |
2238 | * type of request, bidi or uni. In the later case @bidi_bytes is |
2239 | * just ignored. |
2240 | * |
2241 | * Return: |
2242 | * %false - we are done with this request |
2243 | * %true - still buffers pending for this request |
2244 | **/ |
2245 | static bool blk_end_bidi_request(struct request *rq, int error, |
2246 | unsigned int nr_bytes, unsigned int bidi_bytes) |
2247 | { |
2248 | struct request_queue *q = rq->q; |
2249 | unsigned long flags; |
2250 | |
2251 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
2252 | return true; |
2253 | |
2254 | spin_lock_irqsave(q->queue_lock, flags); |
2255 | blk_finish_request(rq, error); |
2256 | spin_unlock_irqrestore(q->queue_lock, flags); |
2257 | |
2258 | return false; |
2259 | } |
2260 | |
2261 | /** |
2262 | * __blk_end_bidi_request - Complete a bidi request with queue lock held |
2263 | * @rq: the request to complete |
2264 | * @error: %0 for success, < %0 for error |
2265 | * @nr_bytes: number of bytes to complete @rq |
2266 | * @bidi_bytes: number of bytes to complete @rq->next_rq |
2267 | * |
2268 | * Description: |
2269 | * Identical to blk_end_bidi_request() except that queue lock is |
2270 | * assumed to be locked on entry and remains so on return. |
2271 | * |
2272 | * Return: |
2273 | * %false - we are done with this request |
2274 | * %true - still buffers pending for this request |
2275 | **/ |
2276 | static bool __blk_end_bidi_request(struct request *rq, int error, |
2277 | unsigned int nr_bytes, unsigned int bidi_bytes) |
2278 | { |
2279 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
2280 | return true; |
2281 | |
2282 | blk_finish_request(rq, error); |
2283 | |
2284 | return false; |
2285 | } |
2286 | |
2287 | /** |
2288 | * blk_end_request - Helper function for drivers to complete the request. |
2289 | * @rq: the request being processed |
2290 | * @error: %0 for success, < %0 for error |
2291 | * @nr_bytes: number of bytes to complete |
2292 | * |
2293 | * Description: |
2294 | * Ends I/O on a number of bytes attached to @rq. |
2295 | * If @rq has leftover, sets it up for the next range of segments. |
2296 | * |
2297 | * Return: |
2298 | * %false - we are done with this request |
2299 | * %true - still buffers pending for this request |
2300 | **/ |
2301 | bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
2302 | { |
2303 | return blk_end_bidi_request(rq, error, nr_bytes, 0); |
2304 | } |
2305 | EXPORT_SYMBOL(blk_end_request); |
2306 | |
2307 | /** |
2308 | * blk_end_request_all - Helper function for drives to finish the request. |
2309 | * @rq: the request to finish |
2310 | * @error: %0 for success, < %0 for error |
2311 | * |
2312 | * Description: |
2313 | * Completely finish @rq. |
2314 | */ |
2315 | void blk_end_request_all(struct request *rq, int error) |
2316 | { |
2317 | bool pending; |
2318 | unsigned int bidi_bytes = 0; |
2319 | |
2320 | if (unlikely(blk_bidi_rq(rq))) |
2321 | bidi_bytes = blk_rq_bytes(rq->next_rq); |
2322 | |
2323 | pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); |
2324 | BUG_ON(pending); |
2325 | } |
2326 | EXPORT_SYMBOL(blk_end_request_all); |
2327 | |
2328 | /** |
2329 | * blk_end_request_cur - Helper function to finish the current request chunk. |
2330 | * @rq: the request to finish the current chunk for |
2331 | * @error: %0 for success, < %0 for error |
2332 | * |
2333 | * Description: |
2334 | * Complete the current consecutively mapped chunk from @rq. |
2335 | * |
2336 | * Return: |
2337 | * %false - we are done with this request |
2338 | * %true - still buffers pending for this request |
2339 | */ |
2340 | bool blk_end_request_cur(struct request *rq, int error) |
2341 | { |
2342 | return blk_end_request(rq, error, blk_rq_cur_bytes(rq)); |
2343 | } |
2344 | EXPORT_SYMBOL(blk_end_request_cur); |
2345 | |
2346 | /** |
2347 | * blk_end_request_err - Finish a request till the next failure boundary. |
2348 | * @rq: the request to finish till the next failure boundary for |
2349 | * @error: must be negative errno |
2350 | * |
2351 | * Description: |
2352 | * Complete @rq till the next failure boundary. |
2353 | * |
2354 | * Return: |
2355 | * %false - we are done with this request |
2356 | * %true - still buffers pending for this request |
2357 | */ |
2358 | bool blk_end_request_err(struct request *rq, int error) |
2359 | { |
2360 | WARN_ON(error >= 0); |
2361 | return blk_end_request(rq, error, blk_rq_err_bytes(rq)); |
2362 | } |
2363 | EXPORT_SYMBOL_GPL(blk_end_request_err); |
2364 | |
2365 | /** |
2366 | * __blk_end_request - Helper function for drivers to complete the request. |
2367 | * @rq: the request being processed |
2368 | * @error: %0 for success, < %0 for error |
2369 | * @nr_bytes: number of bytes to complete |
2370 | * |
2371 | * Description: |
2372 | * Must be called with queue lock held unlike blk_end_request(). |
2373 | * |
2374 | * Return: |
2375 | * %false - we are done with this request |
2376 | * %true - still buffers pending for this request |
2377 | **/ |
2378 | bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
2379 | { |
2380 | return __blk_end_bidi_request(rq, error, nr_bytes, 0); |
2381 | } |
2382 | EXPORT_SYMBOL(__blk_end_request); |
2383 | |
2384 | /** |
2385 | * __blk_end_request_all - Helper function for drives to finish the request. |
2386 | * @rq: the request to finish |
2387 | * @error: %0 for success, < %0 for error |
2388 | * |
2389 | * Description: |
2390 | * Completely finish @rq. Must be called with queue lock held. |
2391 | */ |
2392 | void __blk_end_request_all(struct request *rq, int error) |
2393 | { |
2394 | bool pending; |
2395 | unsigned int bidi_bytes = 0; |
2396 | |
2397 | if (unlikely(blk_bidi_rq(rq))) |
2398 | bidi_bytes = blk_rq_bytes(rq->next_rq); |
2399 | |
2400 | pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); |
2401 | BUG_ON(pending); |
2402 | } |
2403 | EXPORT_SYMBOL(__blk_end_request_all); |
2404 | |
2405 | /** |
2406 | * __blk_end_request_cur - Helper function to finish the current request chunk. |
2407 | * @rq: the request to finish the current chunk for |
2408 | * @error: %0 for success, < %0 for error |
2409 | * |
2410 | * Description: |
2411 | * Complete the current consecutively mapped chunk from @rq. Must |
2412 | * be called with queue lock held. |
2413 | * |
2414 | * Return: |
2415 | * %false - we are done with this request |
2416 | * %true - still buffers pending for this request |
2417 | */ |
2418 | bool __blk_end_request_cur(struct request *rq, int error) |
2419 | { |
2420 | return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); |
2421 | } |
2422 | EXPORT_SYMBOL(__blk_end_request_cur); |
2423 | |
2424 | /** |
2425 | * __blk_end_request_err - Finish a request till the next failure boundary. |
2426 | * @rq: the request to finish till the next failure boundary for |
2427 | * @error: must be negative errno |
2428 | * |
2429 | * Description: |
2430 | * Complete @rq till the next failure boundary. Must be called |
2431 | * with queue lock held. |
2432 | * |
2433 | * Return: |
2434 | * %false - we are done with this request |
2435 | * %true - still buffers pending for this request |
2436 | */ |
2437 | bool __blk_end_request_err(struct request *rq, int error) |
2438 | { |
2439 | WARN_ON(error >= 0); |
2440 | return __blk_end_request(rq, error, blk_rq_err_bytes(rq)); |
2441 | } |
2442 | EXPORT_SYMBOL_GPL(__blk_end_request_err); |
2443 | |
2444 | void blk_rq_bio_prep(struct request_queue *q, struct request *rq, |
2445 | struct bio *bio) |
2446 | { |
2447 | /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */ |
2448 | rq->cmd_flags |= bio->bi_rw & REQ_WRITE; |
2449 | |
2450 | if (bio_has_data(bio)) { |
2451 | rq->nr_phys_segments = bio_phys_segments(q, bio); |
2452 | rq->buffer = bio_data(bio); |
2453 | } |
2454 | rq->__data_len = bio->bi_size; |
2455 | rq->bio = rq->biotail = bio; |
2456 | |
2457 | if (bio->bi_bdev) |
2458 | rq->rq_disk = bio->bi_bdev->bd_disk; |
2459 | } |
2460 | |
2461 | #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE |
2462 | /** |
2463 | * rq_flush_dcache_pages - Helper function to flush all pages in a request |
2464 | * @rq: the request to be flushed |
2465 | * |
2466 | * Description: |
2467 | * Flush all pages in @rq. |
2468 | */ |
2469 | void rq_flush_dcache_pages(struct request *rq) |
2470 | { |
2471 | struct req_iterator iter; |
2472 | struct bio_vec *bvec; |
2473 | |
2474 | rq_for_each_segment(bvec, rq, iter) |
2475 | flush_dcache_page(bvec->bv_page); |
2476 | } |
2477 | EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); |
2478 | #endif |
2479 | |
2480 | /** |
2481 | * blk_lld_busy - Check if underlying low-level drivers of a device are busy |
2482 | * @q : the queue of the device being checked |
2483 | * |
2484 | * Description: |
2485 | * Check if underlying low-level drivers of a device are busy. |
2486 | * If the drivers want to export their busy state, they must set own |
2487 | * exporting function using blk_queue_lld_busy() first. |
2488 | * |
2489 | * Basically, this function is used only by request stacking drivers |
2490 | * to stop dispatching requests to underlying devices when underlying |
2491 | * devices are busy. This behavior helps more I/O merging on the queue |
2492 | * of the request stacking driver and prevents I/O throughput regression |
2493 | * on burst I/O load. |
2494 | * |
2495 | * Return: |
2496 | * 0 - Not busy (The request stacking driver should dispatch request) |
2497 | * 1 - Busy (The request stacking driver should stop dispatching request) |
2498 | */ |
2499 | int blk_lld_busy(struct request_queue *q) |
2500 | { |
2501 | if (q->lld_busy_fn) |
2502 | return q->lld_busy_fn(q); |
2503 | |
2504 | return 0; |
2505 | } |
2506 | EXPORT_SYMBOL_GPL(blk_lld_busy); |
2507 | |
2508 | /** |
2509 | * blk_rq_unprep_clone - Helper function to free all bios in a cloned request |
2510 | * @rq: the clone request to be cleaned up |
2511 | * |
2512 | * Description: |
2513 | * Free all bios in @rq for a cloned request. |
2514 | */ |
2515 | void blk_rq_unprep_clone(struct request *rq) |
2516 | { |
2517 | struct bio *bio; |
2518 | |
2519 | while ((bio = rq->bio) != NULL) { |
2520 | rq->bio = bio->bi_next; |
2521 | |
2522 | bio_put(bio); |
2523 | } |
2524 | } |
2525 | EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); |
2526 | |
2527 | /* |
2528 | * Copy attributes of the original request to the clone request. |
2529 | * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied. |
2530 | */ |
2531 | static void __blk_rq_prep_clone(struct request *dst, struct request *src) |
2532 | { |
2533 | dst->cpu = src->cpu; |
2534 | dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE; |
2535 | dst->cmd_type = src->cmd_type; |
2536 | dst->__sector = blk_rq_pos(src); |
2537 | dst->__data_len = blk_rq_bytes(src); |
2538 | dst->nr_phys_segments = src->nr_phys_segments; |
2539 | dst->ioprio = src->ioprio; |
2540 | dst->extra_len = src->extra_len; |
2541 | } |
2542 | |
2543 | /** |
2544 | * blk_rq_prep_clone - Helper function to setup clone request |
2545 | * @rq: the request to be setup |
2546 | * @rq_src: original request to be cloned |
2547 | * @bs: bio_set that bios for clone are allocated from |
2548 | * @gfp_mask: memory allocation mask for bio |
2549 | * @bio_ctr: setup function to be called for each clone bio. |
2550 | * Returns %0 for success, non %0 for failure. |
2551 | * @data: private data to be passed to @bio_ctr |
2552 | * |
2553 | * Description: |
2554 | * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. |
2555 | * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense) |
2556 | * are not copied, and copying such parts is the caller's responsibility. |
2557 | * Also, pages which the original bios are pointing to are not copied |
2558 | * and the cloned bios just point same pages. |
2559 | * So cloned bios must be completed before original bios, which means |
2560 | * the caller must complete @rq before @rq_src. |
2561 | */ |
2562 | int blk_rq_prep_clone(struct request *rq, struct request *rq_src, |
2563 | struct bio_set *bs, gfp_t gfp_mask, |
2564 | int (*bio_ctr)(struct bio *, struct bio *, void *), |
2565 | void *data) |
2566 | { |
2567 | struct bio *bio, *bio_src; |
2568 | |
2569 | if (!bs) |
2570 | bs = fs_bio_set; |
2571 | |
2572 | blk_rq_init(NULL, rq); |
2573 | |
2574 | __rq_for_each_bio(bio_src, rq_src) { |
2575 | bio = bio_alloc_bioset(gfp_mask, bio_src->bi_max_vecs, bs); |
2576 | if (!bio) |
2577 | goto free_and_out; |
2578 | |
2579 | __bio_clone(bio, bio_src); |
2580 | |
2581 | if (bio_integrity(bio_src) && |
2582 | bio_integrity_clone(bio, bio_src, gfp_mask, bs)) |
2583 | goto free_and_out; |
2584 | |
2585 | if (bio_ctr && bio_ctr(bio, bio_src, data)) |
2586 | goto free_and_out; |
2587 | |
2588 | if (rq->bio) { |
2589 | rq->biotail->bi_next = bio; |
2590 | rq->biotail = bio; |
2591 | } else |
2592 | rq->bio = rq->biotail = bio; |
2593 | } |
2594 | |
2595 | __blk_rq_prep_clone(rq, rq_src); |
2596 | |
2597 | return 0; |
2598 | |
2599 | free_and_out: |
2600 | if (bio) |
2601 | bio_free(bio, bs); |
2602 | blk_rq_unprep_clone(rq); |
2603 | |
2604 | return -ENOMEM; |
2605 | } |
2606 | EXPORT_SYMBOL_GPL(blk_rq_prep_clone); |
2607 | |
2608 | int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) |
2609 | { |
2610 | return queue_work(kblockd_workqueue, work); |
2611 | } |
2612 | EXPORT_SYMBOL(kblockd_schedule_work); |
2613 | |
2614 | int __init blk_dev_init(void) |
2615 | { |
2616 | BUILD_BUG_ON(__REQ_NR_BITS > 8 * |
2617 | sizeof(((struct request *)0)->cmd_flags)); |
2618 | |
2619 | /* used for unplugging and affects IO latency/throughput - HIGHPRI */ |
2620 | kblockd_workqueue = alloc_workqueue("kblockd", |
2621 | WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); |
2622 | if (!kblockd_workqueue) |
2623 | panic("Failed to create kblockd\n"); |
2624 | |
2625 | request_cachep = kmem_cache_create("blkdev_requests", |
2626 | sizeof(struct request), 0, SLAB_PANIC, NULL); |
2627 | |
2628 | blk_requestq_cachep = kmem_cache_create("blkdev_queue", |
2629 | sizeof(struct request_queue), 0, SLAB_PANIC, NULL); |
2630 | |
2631 | return 0; |
2632 | } |
2633 |
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Tags:
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v2.6.34-rc5
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