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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 | } |
131 | EXPORT_SYMBOL(blk_rq_init); |
132 | |
133 | static void req_bio_endio(struct request *rq, struct bio *bio, |
134 | unsigned int nbytes, int error) |
135 | { |
136 | struct request_queue *q = rq->q; |
137 | |
138 | if (&q->bar_rq != rq) { |
139 | if (error) |
140 | clear_bit(BIO_UPTODATE, &bio->bi_flags); |
141 | else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) |
142 | error = -EIO; |
143 | |
144 | if (unlikely(nbytes > bio->bi_size)) { |
145 | printk(KERN_ERR "%s: want %u bytes done, %u left\n", |
146 | __func__, nbytes, bio->bi_size); |
147 | nbytes = bio->bi_size; |
148 | } |
149 | |
150 | if (unlikely(rq->cmd_flags & REQ_QUIET)) |
151 | set_bit(BIO_QUIET, &bio->bi_flags); |
152 | |
153 | bio->bi_size -= nbytes; |
154 | bio->bi_sector += (nbytes >> 9); |
155 | |
156 | if (bio_integrity(bio)) |
157 | bio_integrity_advance(bio, nbytes); |
158 | |
159 | if (bio->bi_size == 0) |
160 | bio_endio(bio, error); |
161 | } else { |
162 | |
163 | /* |
164 | * Okay, this is the barrier request in progress, just |
165 | * record the error; |
166 | */ |
167 | if (error && !q->orderr) |
168 | q->orderr = error; |
169 | } |
170 | } |
171 | |
172 | void blk_dump_rq_flags(struct request *rq, char *msg) |
173 | { |
174 | int bit; |
175 | |
176 | printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg, |
177 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, |
178 | rq->cmd_flags); |
179 | |
180 | printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", |
181 | (unsigned long long)blk_rq_pos(rq), |
182 | blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); |
183 | printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n", |
184 | rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq)); |
185 | |
186 | if (blk_pc_request(rq)) { |
187 | printk(KERN_INFO " cdb: "); |
188 | for (bit = 0; bit < BLK_MAX_CDB; bit++) |
189 | printk("%02x ", rq->cmd[bit]); |
190 | printk("\n"); |
191 | } |
192 | } |
193 | EXPORT_SYMBOL(blk_dump_rq_flags); |
194 | |
195 | /* |
196 | * "plug" the device if there are no outstanding requests: this will |
197 | * force the transfer to start only after we have put all the requests |
198 | * on the list. |
199 | * |
200 | * This is called with interrupts off and no requests on the queue and |
201 | * with the queue lock held. |
202 | */ |
203 | void blk_plug_device(struct request_queue *q) |
204 | { |
205 | WARN_ON(!irqs_disabled()); |
206 | |
207 | /* |
208 | * don't plug a stopped queue, it must be paired with blk_start_queue() |
209 | * which will restart the queueing |
210 | */ |
211 | if (blk_queue_stopped(q)) |
212 | return; |
213 | |
214 | if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) { |
215 | mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); |
216 | trace_block_plug(q); |
217 | } |
218 | } |
219 | EXPORT_SYMBOL(blk_plug_device); |
220 | |
221 | /** |
222 | * blk_plug_device_unlocked - plug a device without queue lock held |
223 | * @q: The &struct request_queue to plug |
224 | * |
225 | * Description: |
226 | * Like @blk_plug_device(), but grabs the queue lock and disables |
227 | * interrupts. |
228 | **/ |
229 | void blk_plug_device_unlocked(struct request_queue *q) |
230 | { |
231 | unsigned long flags; |
232 | |
233 | spin_lock_irqsave(q->queue_lock, flags); |
234 | blk_plug_device(q); |
235 | spin_unlock_irqrestore(q->queue_lock, flags); |
236 | } |
237 | EXPORT_SYMBOL(blk_plug_device_unlocked); |
238 | |
239 | /* |
240 | * remove the queue from the plugged list, if present. called with |
241 | * queue lock held and interrupts disabled. |
242 | */ |
243 | int blk_remove_plug(struct request_queue *q) |
244 | { |
245 | WARN_ON(!irqs_disabled()); |
246 | |
247 | if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q)) |
248 | return 0; |
249 | |
250 | del_timer(&q->unplug_timer); |
251 | return 1; |
252 | } |
253 | EXPORT_SYMBOL(blk_remove_plug); |
254 | |
255 | /* |
256 | * remove the plug and let it rip.. |
257 | */ |
258 | void __generic_unplug_device(struct request_queue *q) |
259 | { |
260 | if (unlikely(blk_queue_stopped(q))) |
261 | return; |
262 | if (!blk_remove_plug(q) && !blk_queue_nonrot(q)) |
263 | return; |
264 | |
265 | q->request_fn(q); |
266 | } |
267 | |
268 | /** |
269 | * generic_unplug_device - fire a request queue |
270 | * @q: The &struct request_queue in question |
271 | * |
272 | * Description: |
273 | * Linux uses plugging to build bigger requests queues before letting |
274 | * the device have at them. If a queue is plugged, the I/O scheduler |
275 | * is still adding and merging requests on the queue. Once the queue |
276 | * gets unplugged, the request_fn defined for the queue is invoked and |
277 | * transfers started. |
278 | **/ |
279 | void generic_unplug_device(struct request_queue *q) |
280 | { |
281 | if (blk_queue_plugged(q)) { |
282 | spin_lock_irq(q->queue_lock); |
283 | __generic_unplug_device(q); |
284 | spin_unlock_irq(q->queue_lock); |
285 | } |
286 | } |
287 | EXPORT_SYMBOL(generic_unplug_device); |
288 | |
289 | static void blk_backing_dev_unplug(struct backing_dev_info *bdi, |
290 | struct page *page) |
291 | { |
292 | struct request_queue *q = bdi->unplug_io_data; |
293 | |
294 | blk_unplug(q); |
295 | } |
296 | |
297 | void blk_unplug_work(struct work_struct *work) |
298 | { |
299 | struct request_queue *q = |
300 | container_of(work, struct request_queue, unplug_work); |
301 | |
302 | trace_block_unplug_io(q); |
303 | q->unplug_fn(q); |
304 | } |
305 | |
306 | void blk_unplug_timeout(unsigned long data) |
307 | { |
308 | struct request_queue *q = (struct request_queue *)data; |
309 | |
310 | trace_block_unplug_timer(q); |
311 | kblockd_schedule_work(q, &q->unplug_work); |
312 | } |
313 | |
314 | void blk_unplug(struct request_queue *q) |
315 | { |
316 | /* |
317 | * devices don't necessarily have an ->unplug_fn defined |
318 | */ |
319 | if (q->unplug_fn) { |
320 | trace_block_unplug_io(q); |
321 | q->unplug_fn(q); |
322 | } |
323 | } |
324 | EXPORT_SYMBOL(blk_unplug); |
325 | |
326 | /** |
327 | * blk_start_queue - restart a previously stopped queue |
328 | * @q: The &struct request_queue in question |
329 | * |
330 | * Description: |
331 | * blk_start_queue() will clear the stop flag on the queue, and call |
332 | * the request_fn for the queue if it was in a stopped state when |
333 | * entered. Also see blk_stop_queue(). Queue lock must be held. |
334 | **/ |
335 | void blk_start_queue(struct request_queue *q) |
336 | { |
337 | WARN_ON(!irqs_disabled()); |
338 | |
339 | queue_flag_clear(QUEUE_FLAG_STOPPED, q); |
340 | __blk_run_queue(q); |
341 | } |
342 | EXPORT_SYMBOL(blk_start_queue); |
343 | |
344 | /** |
345 | * blk_stop_queue - stop a queue |
346 | * @q: The &struct request_queue in question |
347 | * |
348 | * Description: |
349 | * The Linux block layer assumes that a block driver will consume all |
350 | * entries on the request queue when the request_fn strategy is called. |
351 | * Often this will not happen, because of hardware limitations (queue |
352 | * depth settings). If a device driver gets a 'queue full' response, |
353 | * or if it simply chooses not to queue more I/O at one point, it can |
354 | * call this function to prevent the request_fn from being called until |
355 | * the driver has signalled it's ready to go again. This happens by calling |
356 | * blk_start_queue() to restart queue operations. Queue lock must be held. |
357 | **/ |
358 | void blk_stop_queue(struct request_queue *q) |
359 | { |
360 | blk_remove_plug(q); |
361 | queue_flag_set(QUEUE_FLAG_STOPPED, q); |
362 | } |
363 | EXPORT_SYMBOL(blk_stop_queue); |
364 | |
365 | /** |
366 | * blk_sync_queue - cancel any pending callbacks on a queue |
367 | * @q: the queue |
368 | * |
369 | * Description: |
370 | * The block layer may perform asynchronous callback activity |
371 | * on a queue, such as calling the unplug function after a timeout. |
372 | * A block device may call blk_sync_queue to ensure that any |
373 | * such activity is cancelled, thus allowing it to release resources |
374 | * that the callbacks might use. The caller must already have made sure |
375 | * that its ->make_request_fn will not re-add plugging prior to calling |
376 | * this function. |
377 | * |
378 | */ |
379 | void blk_sync_queue(struct request_queue *q) |
380 | { |
381 | del_timer_sync(&q->unplug_timer); |
382 | del_timer_sync(&q->timeout); |
383 | cancel_work_sync(&q->unplug_work); |
384 | } |
385 | EXPORT_SYMBOL(blk_sync_queue); |
386 | |
387 | /** |
388 | * __blk_run_queue - run a single device queue |
389 | * @q: The queue to run |
390 | * |
391 | * Description: |
392 | * See @blk_run_queue. This variant must be called with the queue lock |
393 | * held and interrupts disabled. |
394 | * |
395 | */ |
396 | void __blk_run_queue(struct request_queue *q) |
397 | { |
398 | blk_remove_plug(q); |
399 | |
400 | if (unlikely(blk_queue_stopped(q))) |
401 | return; |
402 | |
403 | if (elv_queue_empty(q)) |
404 | return; |
405 | |
406 | /* |
407 | * Only recurse once to avoid overrunning the stack, let the unplug |
408 | * handling reinvoke the handler shortly if we already got there. |
409 | */ |
410 | if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { |
411 | q->request_fn(q); |
412 | queue_flag_clear(QUEUE_FLAG_REENTER, q); |
413 | } else { |
414 | queue_flag_set(QUEUE_FLAG_PLUGGED, q); |
415 | kblockd_schedule_work(q, &q->unplug_work); |
416 | } |
417 | } |
418 | EXPORT_SYMBOL(__blk_run_queue); |
419 | |
420 | /** |
421 | * blk_run_queue - run a single device queue |
422 | * @q: The queue to run |
423 | * |
424 | * Description: |
425 | * Invoke request handling on this queue, if it has pending work to do. |
426 | * May be used to restart queueing when a request has completed. |
427 | */ |
428 | void blk_run_queue(struct request_queue *q) |
429 | { |
430 | unsigned long flags; |
431 | |
432 | spin_lock_irqsave(q->queue_lock, flags); |
433 | __blk_run_queue(q); |
434 | spin_unlock_irqrestore(q->queue_lock, flags); |
435 | } |
436 | EXPORT_SYMBOL(blk_run_queue); |
437 | |
438 | void blk_put_queue(struct request_queue *q) |
439 | { |
440 | kobject_put(&q->kobj); |
441 | } |
442 | |
443 | void blk_cleanup_queue(struct request_queue *q) |
444 | { |
445 | /* |
446 | * We know we have process context here, so we can be a little |
447 | * cautious and ensure that pending block actions on this device |
448 | * are done before moving on. Going into this function, we should |
449 | * not have processes doing IO to this device. |
450 | */ |
451 | blk_sync_queue(q); |
452 | |
453 | mutex_lock(&q->sysfs_lock); |
454 | queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q); |
455 | mutex_unlock(&q->sysfs_lock); |
456 | |
457 | if (q->elevator) |
458 | elevator_exit(q->elevator); |
459 | |
460 | blk_put_queue(q); |
461 | } |
462 | EXPORT_SYMBOL(blk_cleanup_queue); |
463 | |
464 | static int blk_init_free_list(struct request_queue *q) |
465 | { |
466 | struct request_list *rl = &q->rq; |
467 | |
468 | rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; |
469 | rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; |
470 | rl->elvpriv = 0; |
471 | init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); |
472 | init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); |
473 | |
474 | rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
475 | mempool_free_slab, request_cachep, q->node); |
476 | |
477 | if (!rl->rq_pool) |
478 | return -ENOMEM; |
479 | |
480 | return 0; |
481 | } |
482 | |
483 | struct request_queue *blk_alloc_queue(gfp_t gfp_mask) |
484 | { |
485 | return blk_alloc_queue_node(gfp_mask, -1); |
486 | } |
487 | EXPORT_SYMBOL(blk_alloc_queue); |
488 | |
489 | struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) |
490 | { |
491 | struct request_queue *q; |
492 | int err; |
493 | |
494 | q = kmem_cache_alloc_node(blk_requestq_cachep, |
495 | gfp_mask | __GFP_ZERO, node_id); |
496 | if (!q) |
497 | return NULL; |
498 | |
499 | q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; |
500 | q->backing_dev_info.unplug_io_data = q; |
501 | q->backing_dev_info.ra_pages = |
502 | (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; |
503 | q->backing_dev_info.state = 0; |
504 | q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; |
505 | q->backing_dev_info.name = "block"; |
506 | |
507 | err = bdi_init(&q->backing_dev_info); |
508 | if (err) { |
509 | kmem_cache_free(blk_requestq_cachep, q); |
510 | return NULL; |
511 | } |
512 | |
513 | init_timer(&q->unplug_timer); |
514 | setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); |
515 | INIT_LIST_HEAD(&q->timeout_list); |
516 | INIT_WORK(&q->unplug_work, blk_unplug_work); |
517 | |
518 | kobject_init(&q->kobj, &blk_queue_ktype); |
519 | |
520 | mutex_init(&q->sysfs_lock); |
521 | spin_lock_init(&q->__queue_lock); |
522 | |
523 | return q; |
524 | } |
525 | EXPORT_SYMBOL(blk_alloc_queue_node); |
526 | |
527 | /** |
528 | * blk_init_queue - prepare a request queue for use with a block device |
529 | * @rfn: The function to be called to process requests that have been |
530 | * placed on the queue. |
531 | * @lock: Request queue spin lock |
532 | * |
533 | * Description: |
534 | * If a block device wishes to use the standard request handling procedures, |
535 | * which sorts requests and coalesces adjacent requests, then it must |
536 | * call blk_init_queue(). The function @rfn will be called when there |
537 | * are requests on the queue that need to be processed. If the device |
538 | * supports plugging, then @rfn may not be called immediately when requests |
539 | * are available on the queue, but may be called at some time later instead. |
540 | * Plugged queues are generally unplugged when a buffer belonging to one |
541 | * of the requests on the queue is needed, or due to memory pressure. |
542 | * |
543 | * @rfn is not required, or even expected, to remove all requests off the |
544 | * queue, but only as many as it can handle at a time. If it does leave |
545 | * requests on the queue, it is responsible for arranging that the requests |
546 | * get dealt with eventually. |
547 | * |
548 | * The queue spin lock must be held while manipulating the requests on the |
549 | * request queue; this lock will be taken also from interrupt context, so irq |
550 | * disabling is needed for it. |
551 | * |
552 | * Function returns a pointer to the initialized request queue, or %NULL if |
553 | * it didn't succeed. |
554 | * |
555 | * Note: |
556 | * blk_init_queue() must be paired with a blk_cleanup_queue() call |
557 | * when the block device is deactivated (such as at module unload). |
558 | **/ |
559 | |
560 | struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) |
561 | { |
562 | return blk_init_queue_node(rfn, lock, -1); |
563 | } |
564 | EXPORT_SYMBOL(blk_init_queue); |
565 | |
566 | struct request_queue * |
567 | blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) |
568 | { |
569 | struct request_queue *q = blk_alloc_queue_node(GFP_KERNEL, node_id); |
570 | |
571 | if (!q) |
572 | return NULL; |
573 | |
574 | q->node = node_id; |
575 | if (blk_init_free_list(q)) { |
576 | kmem_cache_free(blk_requestq_cachep, q); |
577 | return NULL; |
578 | } |
579 | |
580 | q->request_fn = rfn; |
581 | q->prep_rq_fn = NULL; |
582 | q->unplug_fn = generic_unplug_device; |
583 | q->queue_flags = QUEUE_FLAG_DEFAULT; |
584 | q->queue_lock = lock; |
585 | |
586 | /* |
587 | * This also sets hw/phys segments, boundary and size |
588 | */ |
589 | blk_queue_make_request(q, __make_request); |
590 | |
591 | q->sg_reserved_size = INT_MAX; |
592 | |
593 | /* |
594 | * all done |
595 | */ |
596 | if (!elevator_init(q, NULL)) { |
597 | blk_queue_congestion_threshold(q); |
598 | return q; |
599 | } |
600 | |
601 | blk_put_queue(q); |
602 | return NULL; |
603 | } |
604 | EXPORT_SYMBOL(blk_init_queue_node); |
605 | |
606 | int blk_get_queue(struct request_queue *q) |
607 | { |
608 | if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { |
609 | kobject_get(&q->kobj); |
610 | return 0; |
611 | } |
612 | |
613 | return 1; |
614 | } |
615 | |
616 | static inline void blk_free_request(struct request_queue *q, struct request *rq) |
617 | { |
618 | if (rq->cmd_flags & REQ_ELVPRIV) |
619 | elv_put_request(q, rq); |
620 | mempool_free(rq, q->rq.rq_pool); |
621 | } |
622 | |
623 | static struct request * |
624 | blk_alloc_request(struct request_queue *q, int flags, int priv, gfp_t gfp_mask) |
625 | { |
626 | struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); |
627 | |
628 | if (!rq) |
629 | return NULL; |
630 | |
631 | blk_rq_init(q, rq); |
632 | |
633 | rq->cmd_flags = flags | REQ_ALLOCED; |
634 | |
635 | if (priv) { |
636 | if (unlikely(elv_set_request(q, rq, gfp_mask))) { |
637 | mempool_free(rq, q->rq.rq_pool); |
638 | return NULL; |
639 | } |
640 | rq->cmd_flags |= REQ_ELVPRIV; |
641 | } |
642 | |
643 | return rq; |
644 | } |
645 | |
646 | /* |
647 | * ioc_batching returns true if the ioc is a valid batching request and |
648 | * should be given priority access to a request. |
649 | */ |
650 | static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) |
651 | { |
652 | if (!ioc) |
653 | return 0; |
654 | |
655 | /* |
656 | * Make sure the process is able to allocate at least 1 request |
657 | * even if the batch times out, otherwise we could theoretically |
658 | * lose wakeups. |
659 | */ |
660 | return ioc->nr_batch_requests == q->nr_batching || |
661 | (ioc->nr_batch_requests > 0 |
662 | && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); |
663 | } |
664 | |
665 | /* |
666 | * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This |
667 | * will cause the process to be a "batcher" on all queues in the system. This |
668 | * is the behaviour we want though - once it gets a wakeup it should be given |
669 | * a nice run. |
670 | */ |
671 | static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) |
672 | { |
673 | if (!ioc || ioc_batching(q, ioc)) |
674 | return; |
675 | |
676 | ioc->nr_batch_requests = q->nr_batching; |
677 | ioc->last_waited = jiffies; |
678 | } |
679 | |
680 | static void __freed_request(struct request_queue *q, int sync) |
681 | { |
682 | struct request_list *rl = &q->rq; |
683 | |
684 | if (rl->count[sync] < queue_congestion_off_threshold(q)) |
685 | blk_clear_queue_congested(q, sync); |
686 | |
687 | if (rl->count[sync] + 1 <= q->nr_requests) { |
688 | if (waitqueue_active(&rl->wait[sync])) |
689 | wake_up(&rl->wait[sync]); |
690 | |
691 | blk_clear_queue_full(q, sync); |
692 | } |
693 | } |
694 | |
695 | /* |
696 | * A request has just been released. Account for it, update the full and |
697 | * congestion status, wake up any waiters. Called under q->queue_lock. |
698 | */ |
699 | static void freed_request(struct request_queue *q, int sync, int priv) |
700 | { |
701 | struct request_list *rl = &q->rq; |
702 | |
703 | rl->count[sync]--; |
704 | if (priv) |
705 | rl->elvpriv--; |
706 | |
707 | __freed_request(q, sync); |
708 | |
709 | if (unlikely(rl->starved[sync ^ 1])) |
710 | __freed_request(q, sync ^ 1); |
711 | } |
712 | |
713 | /* |
714 | * Get a free request, queue_lock must be held. |
715 | * Returns NULL on failure, with queue_lock held. |
716 | * Returns !NULL on success, with queue_lock *not held*. |
717 | */ |
718 | static struct request *get_request(struct request_queue *q, int rw_flags, |
719 | struct bio *bio, gfp_t gfp_mask) |
720 | { |
721 | struct request *rq = NULL; |
722 | struct request_list *rl = &q->rq; |
723 | struct io_context *ioc = NULL; |
724 | const bool is_sync = rw_is_sync(rw_flags) != 0; |
725 | int may_queue, priv; |
726 | |
727 | may_queue = elv_may_queue(q, rw_flags); |
728 | if (may_queue == ELV_MQUEUE_NO) |
729 | goto rq_starved; |
730 | |
731 | if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { |
732 | if (rl->count[is_sync]+1 >= q->nr_requests) { |
733 | ioc = current_io_context(GFP_ATOMIC, q->node); |
734 | /* |
735 | * The queue will fill after this allocation, so set |
736 | * it as full, and mark this process as "batching". |
737 | * This process will be allowed to complete a batch of |
738 | * requests, others will be blocked. |
739 | */ |
740 | if (!blk_queue_full(q, is_sync)) { |
741 | ioc_set_batching(q, ioc); |
742 | blk_set_queue_full(q, is_sync); |
743 | } else { |
744 | if (may_queue != ELV_MQUEUE_MUST |
745 | && !ioc_batching(q, ioc)) { |
746 | /* |
747 | * The queue is full and the allocating |
748 | * process is not a "batcher", and not |
749 | * exempted by the IO scheduler |
750 | */ |
751 | goto out; |
752 | } |
753 | } |
754 | } |
755 | blk_set_queue_congested(q, is_sync); |
756 | } |
757 | |
758 | /* |
759 | * Only allow batching queuers to allocate up to 50% over the defined |
760 | * limit of requests, otherwise we could have thousands of requests |
761 | * allocated with any setting of ->nr_requests |
762 | */ |
763 | if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) |
764 | goto out; |
765 | |
766 | rl->count[is_sync]++; |
767 | rl->starved[is_sync] = 0; |
768 | |
769 | priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
770 | if (priv) |
771 | rl->elvpriv++; |
772 | |
773 | if (blk_queue_io_stat(q)) |
774 | rw_flags |= REQ_IO_STAT; |
775 | spin_unlock_irq(q->queue_lock); |
776 | |
777 | rq = blk_alloc_request(q, rw_flags, priv, gfp_mask); |
778 | if (unlikely(!rq)) { |
779 | /* |
780 | * Allocation failed presumably due to memory. Undo anything |
781 | * we might have messed up. |
782 | * |
783 | * Allocating task should really be put onto the front of the |
784 | * wait queue, but this is pretty rare. |
785 | */ |
786 | spin_lock_irq(q->queue_lock); |
787 | freed_request(q, is_sync, priv); |
788 | |
789 | /* |
790 | * in the very unlikely event that allocation failed and no |
791 | * requests for this direction was pending, mark us starved |
792 | * so that freeing of a request in the other direction will |
793 | * notice us. another possible fix would be to split the |
794 | * rq mempool into READ and WRITE |
795 | */ |
796 | rq_starved: |
797 | if (unlikely(rl->count[is_sync] == 0)) |
798 | rl->starved[is_sync] = 1; |
799 | |
800 | goto out; |
801 | } |
802 | |
803 | /* |
804 | * ioc may be NULL here, and ioc_batching will be false. That's |
805 | * OK, if the queue is under the request limit then requests need |
806 | * not count toward the nr_batch_requests limit. There will always |
807 | * be some limit enforced by BLK_BATCH_TIME. |
808 | */ |
809 | if (ioc_batching(q, ioc)) |
810 | ioc->nr_batch_requests--; |
811 | |
812 | trace_block_getrq(q, bio, rw_flags & 1); |
813 | out: |
814 | return rq; |
815 | } |
816 | |
817 | /* |
818 | * No available requests for this queue, unplug the device and wait for some |
819 | * requests to become available. |
820 | * |
821 | * Called with q->queue_lock held, and returns with it unlocked. |
822 | */ |
823 | static struct request *get_request_wait(struct request_queue *q, int rw_flags, |
824 | struct bio *bio) |
825 | { |
826 | const bool is_sync = rw_is_sync(rw_flags) != 0; |
827 | struct request *rq; |
828 | |
829 | rq = get_request(q, rw_flags, bio, GFP_NOIO); |
830 | while (!rq) { |
831 | DEFINE_WAIT(wait); |
832 | struct io_context *ioc; |
833 | struct request_list *rl = &q->rq; |
834 | |
835 | prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, |
836 | TASK_UNINTERRUPTIBLE); |
837 | |
838 | trace_block_sleeprq(q, bio, rw_flags & 1); |
839 | |
840 | __generic_unplug_device(q); |
841 | spin_unlock_irq(q->queue_lock); |
842 | io_schedule(); |
843 | |
844 | /* |
845 | * After sleeping, we become a "batching" process and |
846 | * will be able to allocate at least one request, and |
847 | * up to a big batch of them for a small period time. |
848 | * See ioc_batching, ioc_set_batching |
849 | */ |
850 | ioc = current_io_context(GFP_NOIO, q->node); |
851 | ioc_set_batching(q, ioc); |
852 | |
853 | spin_lock_irq(q->queue_lock); |
854 | finish_wait(&rl->wait[is_sync], &wait); |
855 | |
856 | rq = get_request(q, rw_flags, bio, GFP_NOIO); |
857 | }; |
858 | |
859 | return rq; |
860 | } |
861 | |
862 | struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) |
863 | { |
864 | struct request *rq; |
865 | |
866 | BUG_ON(rw != READ && rw != WRITE); |
867 | |
868 | spin_lock_irq(q->queue_lock); |
869 | if (gfp_mask & __GFP_WAIT) { |
870 | rq = get_request_wait(q, rw, NULL); |
871 | } else { |
872 | rq = get_request(q, rw, NULL, gfp_mask); |
873 | if (!rq) |
874 | spin_unlock_irq(q->queue_lock); |
875 | } |
876 | /* q->queue_lock is unlocked at this point */ |
877 | |
878 | return rq; |
879 | } |
880 | EXPORT_SYMBOL(blk_get_request); |
881 | |
882 | /** |
883 | * blk_make_request - given a bio, allocate a corresponding struct request. |
884 | * @q: target request queue |
885 | * @bio: The bio describing the memory mappings that will be submitted for IO. |
886 | * It may be a chained-bio properly constructed by block/bio layer. |
887 | * @gfp_mask: gfp flags to be used for memory allocation |
888 | * |
889 | * blk_make_request is the parallel of generic_make_request for BLOCK_PC |
890 | * type commands. Where the struct request needs to be farther initialized by |
891 | * the caller. It is passed a &struct bio, which describes the memory info of |
892 | * the I/O transfer. |
893 | * |
894 | * The caller of blk_make_request must make sure that bi_io_vec |
895 | * are set to describe the memory buffers. That bio_data_dir() will return |
896 | * the needed direction of the request. (And all bio's in the passed bio-chain |
897 | * are properly set accordingly) |
898 | * |
899 | * If called under none-sleepable conditions, mapped bio buffers must not |
900 | * need bouncing, by calling the appropriate masked or flagged allocator, |
901 | * suitable for the target device. Otherwise the call to blk_queue_bounce will |
902 | * BUG. |
903 | * |
904 | * WARNING: When allocating/cloning a bio-chain, careful consideration should be |
905 | * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for |
906 | * anything but the first bio in the chain. Otherwise you risk waiting for IO |
907 | * completion of a bio that hasn't been submitted yet, thus resulting in a |
908 | * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead |
909 | * of bio_alloc(), as that avoids the mempool deadlock. |
910 | * If possible a big IO should be split into smaller parts when allocation |
911 | * fails. Partial allocation should not be an error, or you risk a live-lock. |
912 | */ |
913 | struct request *blk_make_request(struct request_queue *q, struct bio *bio, |
914 | gfp_t gfp_mask) |
915 | { |
916 | struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask); |
917 | |
918 | if (unlikely(!rq)) |
919 | return ERR_PTR(-ENOMEM); |
920 | |
921 | for_each_bio(bio) { |
922 | struct bio *bounce_bio = bio; |
923 | int ret; |
924 | |
925 | blk_queue_bounce(q, &bounce_bio); |
926 | ret = blk_rq_append_bio(q, rq, bounce_bio); |
927 | if (unlikely(ret)) { |
928 | blk_put_request(rq); |
929 | return ERR_PTR(ret); |
930 | } |
931 | } |
932 | |
933 | return rq; |
934 | } |
935 | EXPORT_SYMBOL(blk_make_request); |
936 | |
937 | /** |
938 | * blk_requeue_request - put a request back on queue |
939 | * @q: request queue where request should be inserted |
940 | * @rq: request to be inserted |
941 | * |
942 | * Description: |
943 | * Drivers often keep queueing requests until the hardware cannot accept |
944 | * more, when that condition happens we need to put the request back |
945 | * on the queue. Must be called with queue lock held. |
946 | */ |
947 | void blk_requeue_request(struct request_queue *q, struct request *rq) |
948 | { |
949 | blk_delete_timer(rq); |
950 | blk_clear_rq_complete(rq); |
951 | trace_block_rq_requeue(q, rq); |
952 | |
953 | if (blk_rq_tagged(rq)) |
954 | blk_queue_end_tag(q, rq); |
955 | |
956 | BUG_ON(blk_queued_rq(rq)); |
957 | |
958 | elv_requeue_request(q, rq); |
959 | } |
960 | EXPORT_SYMBOL(blk_requeue_request); |
961 | |
962 | /** |
963 | * blk_insert_request - insert a special request into a request queue |
964 | * @q: request queue where request should be inserted |
965 | * @rq: request to be inserted |
966 | * @at_head: insert request at head or tail of queue |
967 | * @data: private data |
968 | * |
969 | * Description: |
970 | * Many block devices need to execute commands asynchronously, so they don't |
971 | * block the whole kernel from preemption during request execution. This is |
972 | * accomplished normally by inserting aritficial requests tagged as |
973 | * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them |
974 | * be scheduled for actual execution by the request queue. |
975 | * |
976 | * We have the option of inserting the head or the tail of the queue. |
977 | * Typically we use the tail for new ioctls and so forth. We use the head |
978 | * of the queue for things like a QUEUE_FULL message from a device, or a |
979 | * host that is unable to accept a particular command. |
980 | */ |
981 | void blk_insert_request(struct request_queue *q, struct request *rq, |
982 | int at_head, void *data) |
983 | { |
984 | int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; |
985 | unsigned long flags; |
986 | |
987 | /* |
988 | * tell I/O scheduler that this isn't a regular read/write (ie it |
989 | * must not attempt merges on this) and that it acts as a soft |
990 | * barrier |
991 | */ |
992 | rq->cmd_type = REQ_TYPE_SPECIAL; |
993 | |
994 | rq->special = data; |
995 | |
996 | spin_lock_irqsave(q->queue_lock, flags); |
997 | |
998 | /* |
999 | * If command is tagged, release the tag |
1000 | */ |
1001 | if (blk_rq_tagged(rq)) |
1002 | blk_queue_end_tag(q, rq); |
1003 | |
1004 | drive_stat_acct(rq, 1); |
1005 | __elv_add_request(q, rq, where, 0); |
1006 | __blk_run_queue(q); |
1007 | spin_unlock_irqrestore(q->queue_lock, flags); |
1008 | } |
1009 | EXPORT_SYMBOL(blk_insert_request); |
1010 | |
1011 | /* |
1012 | * add-request adds a request to the linked list. |
1013 | * queue lock is held and interrupts disabled, as we muck with the |
1014 | * request queue list. |
1015 | */ |
1016 | static inline void add_request(struct request_queue *q, struct request *req) |
1017 | { |
1018 | drive_stat_acct(req, 1); |
1019 | |
1020 | /* |
1021 | * elevator indicated where it wants this request to be |
1022 | * inserted at elevator_merge time |
1023 | */ |
1024 | __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0); |
1025 | } |
1026 | |
1027 | static void part_round_stats_single(int cpu, struct hd_struct *part, |
1028 | unsigned long now) |
1029 | { |
1030 | if (now == part->stamp) |
1031 | return; |
1032 | |
1033 | if (part_in_flight(part)) { |
1034 | __part_stat_add(cpu, part, time_in_queue, |
1035 | part_in_flight(part) * (now - part->stamp)); |
1036 | __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); |
1037 | } |
1038 | part->stamp = now; |
1039 | } |
1040 | |
1041 | /** |
1042 | * part_round_stats() - Round off the performance stats on a struct disk_stats. |
1043 | * @cpu: cpu number for stats access |
1044 | * @part: target partition |
1045 | * |
1046 | * The average IO queue length and utilisation statistics are maintained |
1047 | * by observing the current state of the queue length and the amount of |
1048 | * time it has been in this state for. |
1049 | * |
1050 | * Normally, that accounting is done on IO completion, but that can result |
1051 | * in more than a second's worth of IO being accounted for within any one |
1052 | * second, leading to >100% utilisation. To deal with that, we call this |
1053 | * function to do a round-off before returning the results when reading |
1054 | * /proc/diskstats. This accounts immediately for all queue usage up to |
1055 | * the current jiffies and restarts the counters again. |
1056 | */ |
1057 | void part_round_stats(int cpu, struct hd_struct *part) |
1058 | { |
1059 | unsigned long now = jiffies; |
1060 | |
1061 | if (part->partno) |
1062 | part_round_stats_single(cpu, &part_to_disk(part)->part0, now); |
1063 | part_round_stats_single(cpu, part, now); |
1064 | } |
1065 | EXPORT_SYMBOL_GPL(part_round_stats); |
1066 | |
1067 | /* |
1068 | * queue lock must be held |
1069 | */ |
1070 | void __blk_put_request(struct request_queue *q, struct request *req) |
1071 | { |
1072 | if (unlikely(!q)) |
1073 | return; |
1074 | if (unlikely(--req->ref_count)) |
1075 | return; |
1076 | |
1077 | elv_completed_request(q, req); |
1078 | |
1079 | /* this is a bio leak */ |
1080 | WARN_ON(req->bio != NULL); |
1081 | |
1082 | /* |
1083 | * Request may not have originated from ll_rw_blk. if not, |
1084 | * it didn't come out of our reserved rq pools |
1085 | */ |
1086 | if (req->cmd_flags & REQ_ALLOCED) { |
1087 | int is_sync = rq_is_sync(req) != 0; |
1088 | int priv = req->cmd_flags & REQ_ELVPRIV; |
1089 | |
1090 | BUG_ON(!list_empty(&req->queuelist)); |
1091 | BUG_ON(!hlist_unhashed(&req->hash)); |
1092 | |
1093 | blk_free_request(q, req); |
1094 | freed_request(q, is_sync, priv); |
1095 | } |
1096 | } |
1097 | EXPORT_SYMBOL_GPL(__blk_put_request); |
1098 | |
1099 | void blk_put_request(struct request *req) |
1100 | { |
1101 | unsigned long flags; |
1102 | struct request_queue *q = req->q; |
1103 | |
1104 | spin_lock_irqsave(q->queue_lock, flags); |
1105 | __blk_put_request(q, req); |
1106 | spin_unlock_irqrestore(q->queue_lock, flags); |
1107 | } |
1108 | EXPORT_SYMBOL(blk_put_request); |
1109 | |
1110 | void init_request_from_bio(struct request *req, struct bio *bio) |
1111 | { |
1112 | req->cpu = bio->bi_comp_cpu; |
1113 | req->cmd_type = REQ_TYPE_FS; |
1114 | |
1115 | /* |
1116 | * Inherit FAILFAST from bio (for read-ahead, and explicit |
1117 | * FAILFAST). FAILFAST flags are identical for req and bio. |
1118 | */ |
1119 | if (bio_rw_flagged(bio, BIO_RW_AHEAD)) |
1120 | req->cmd_flags |= REQ_FAILFAST_MASK; |
1121 | else |
1122 | req->cmd_flags |= bio->bi_rw & REQ_FAILFAST_MASK; |
1123 | |
1124 | if (unlikely(bio_rw_flagged(bio, BIO_RW_DISCARD))) { |
1125 | req->cmd_flags |= REQ_DISCARD; |
1126 | if (bio_rw_flagged(bio, BIO_RW_BARRIER)) |
1127 | req->cmd_flags |= REQ_SOFTBARRIER; |
1128 | } else if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) |
1129 | req->cmd_flags |= REQ_HARDBARRIER; |
1130 | |
1131 | if (bio_rw_flagged(bio, BIO_RW_SYNCIO)) |
1132 | req->cmd_flags |= REQ_RW_SYNC; |
1133 | if (bio_rw_flagged(bio, BIO_RW_META)) |
1134 | req->cmd_flags |= REQ_RW_META; |
1135 | if (bio_rw_flagged(bio, BIO_RW_NOIDLE)) |
1136 | req->cmd_flags |= REQ_NOIDLE; |
1137 | |
1138 | req->errors = 0; |
1139 | req->__sector = bio->bi_sector; |
1140 | req->ioprio = bio_prio(bio); |
1141 | blk_rq_bio_prep(req->q, req, bio); |
1142 | } |
1143 | |
1144 | /* |
1145 | * Only disabling plugging for non-rotational devices if it does tagging |
1146 | * as well, otherwise we do need the proper merging |
1147 | */ |
1148 | static inline bool queue_should_plug(struct request_queue *q) |
1149 | { |
1150 | return !(blk_queue_nonrot(q) && blk_queue_tagged(q)); |
1151 | } |
1152 | |
1153 | static int __make_request(struct request_queue *q, struct bio *bio) |
1154 | { |
1155 | struct request *req; |
1156 | int el_ret; |
1157 | unsigned int bytes = bio->bi_size; |
1158 | const unsigned short prio = bio_prio(bio); |
1159 | const bool sync = bio_rw_flagged(bio, BIO_RW_SYNCIO); |
1160 | const bool unplug = bio_rw_flagged(bio, BIO_RW_UNPLUG); |
1161 | const unsigned int ff = bio->bi_rw & REQ_FAILFAST_MASK; |
1162 | int rw_flags; |
1163 | |
1164 | if (bio_rw_flagged(bio, BIO_RW_BARRIER) && |
1165 | (q->next_ordered == QUEUE_ORDERED_NONE)) { |
1166 | bio_endio(bio, -EOPNOTSUPP); |
1167 | return 0; |
1168 | } |
1169 | /* |
1170 | * low level driver can indicate that it wants pages above a |
1171 | * certain limit bounced to low memory (ie for highmem, or even |
1172 | * ISA dma in theory) |
1173 | */ |
1174 | blk_queue_bounce(q, &bio); |
1175 | |
1176 | spin_lock_irq(q->queue_lock); |
1177 | |
1178 | if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER)) || elv_queue_empty(q)) |
1179 | goto get_rq; |
1180 | |
1181 | el_ret = elv_merge(q, &req, bio); |
1182 | switch (el_ret) { |
1183 | case ELEVATOR_BACK_MERGE: |
1184 | BUG_ON(!rq_mergeable(req)); |
1185 | |
1186 | if (!ll_back_merge_fn(q, req, bio)) |
1187 | break; |
1188 | |
1189 | trace_block_bio_backmerge(q, bio); |
1190 | |
1191 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) |
1192 | blk_rq_set_mixed_merge(req); |
1193 | |
1194 | req->biotail->bi_next = bio; |
1195 | req->biotail = bio; |
1196 | req->__data_len += bytes; |
1197 | req->ioprio = ioprio_best(req->ioprio, prio); |
1198 | if (!blk_rq_cpu_valid(req)) |
1199 | req->cpu = bio->bi_comp_cpu; |
1200 | drive_stat_acct(req, 0); |
1201 | if (!attempt_back_merge(q, req)) |
1202 | elv_merged_request(q, req, el_ret); |
1203 | goto out; |
1204 | |
1205 | case ELEVATOR_FRONT_MERGE: |
1206 | BUG_ON(!rq_mergeable(req)); |
1207 | |
1208 | if (!ll_front_merge_fn(q, req, bio)) |
1209 | break; |
1210 | |
1211 | trace_block_bio_frontmerge(q, bio); |
1212 | |
1213 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) { |
1214 | blk_rq_set_mixed_merge(req); |
1215 | req->cmd_flags &= ~REQ_FAILFAST_MASK; |
1216 | req->cmd_flags |= ff; |
1217 | } |
1218 | |
1219 | bio->bi_next = req->bio; |
1220 | req->bio = bio; |
1221 | |
1222 | /* |
1223 | * may not be valid. if the low level driver said |
1224 | * it didn't need a bounce buffer then it better |
1225 | * not touch req->buffer either... |
1226 | */ |
1227 | req->buffer = bio_data(bio); |
1228 | req->__sector = bio->bi_sector; |
1229 | req->__data_len += bytes; |
1230 | req->ioprio = ioprio_best(req->ioprio, prio); |
1231 | if (!blk_rq_cpu_valid(req)) |
1232 | req->cpu = bio->bi_comp_cpu; |
1233 | drive_stat_acct(req, 0); |
1234 | if (!attempt_front_merge(q, req)) |
1235 | elv_merged_request(q, req, el_ret); |
1236 | goto out; |
1237 | |
1238 | /* ELV_NO_MERGE: elevator says don't/can't merge. */ |
1239 | default: |
1240 | ; |
1241 | } |
1242 | |
1243 | get_rq: |
1244 | /* |
1245 | * This sync check and mask will be re-done in init_request_from_bio(), |
1246 | * but we need to set it earlier to expose the sync flag to the |
1247 | * rq allocator and io schedulers. |
1248 | */ |
1249 | rw_flags = bio_data_dir(bio); |
1250 | if (sync) |
1251 | rw_flags |= REQ_RW_SYNC; |
1252 | |
1253 | /* |
1254 | * Grab a free request. This is might sleep but can not fail. |
1255 | * Returns with the queue unlocked. |
1256 | */ |
1257 | req = get_request_wait(q, rw_flags, bio); |
1258 | |
1259 | /* |
1260 | * After dropping the lock and possibly sleeping here, our request |
1261 | * may now be mergeable after it had proven unmergeable (above). |
1262 | * We don't worry about that case for efficiency. It won't happen |
1263 | * often, and the elevators are able to handle it. |
1264 | */ |
1265 | init_request_from_bio(req, bio); |
1266 | |
1267 | spin_lock_irq(q->queue_lock); |
1268 | if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) || |
1269 | bio_flagged(bio, BIO_CPU_AFFINE)) |
1270 | req->cpu = blk_cpu_to_group(smp_processor_id()); |
1271 | if (queue_should_plug(q) && elv_queue_empty(q)) |
1272 | blk_plug_device(q); |
1273 | add_request(q, req); |
1274 | out: |
1275 | if (unplug || !queue_should_plug(q)) |
1276 | __generic_unplug_device(q); |
1277 | spin_unlock_irq(q->queue_lock); |
1278 | return 0; |
1279 | } |
1280 | |
1281 | /* |
1282 | * If bio->bi_dev is a partition, remap the location |
1283 | */ |
1284 | static inline void blk_partition_remap(struct bio *bio) |
1285 | { |
1286 | struct block_device *bdev = bio->bi_bdev; |
1287 | |
1288 | if (bio_sectors(bio) && bdev != bdev->bd_contains) { |
1289 | struct hd_struct *p = bdev->bd_part; |
1290 | |
1291 | bio->bi_sector += p->start_sect; |
1292 | bio->bi_bdev = bdev->bd_contains; |
1293 | |
1294 | trace_block_remap(bdev_get_queue(bio->bi_bdev), bio, |
1295 | bdev->bd_dev, |
1296 | bio->bi_sector - p->start_sect); |
1297 | } |
1298 | } |
1299 | |
1300 | static void handle_bad_sector(struct bio *bio) |
1301 | { |
1302 | char b[BDEVNAME_SIZE]; |
1303 | |
1304 | printk(KERN_INFO "attempt to access beyond end of device\n"); |
1305 | printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", |
1306 | bdevname(bio->bi_bdev, b), |
1307 | bio->bi_rw, |
1308 | (unsigned long long)bio->bi_sector + bio_sectors(bio), |
1309 | (long long)(bio->bi_bdev->bd_inode->i_size >> 9)); |
1310 | |
1311 | set_bit(BIO_EOF, &bio->bi_flags); |
1312 | } |
1313 | |
1314 | #ifdef CONFIG_FAIL_MAKE_REQUEST |
1315 | |
1316 | static DECLARE_FAULT_ATTR(fail_make_request); |
1317 | |
1318 | static int __init setup_fail_make_request(char *str) |
1319 | { |
1320 | return setup_fault_attr(&fail_make_request, str); |
1321 | } |
1322 | __setup("fail_make_request=", setup_fail_make_request); |
1323 | |
1324 | static int should_fail_request(struct bio *bio) |
1325 | { |
1326 | struct hd_struct *part = bio->bi_bdev->bd_part; |
1327 | |
1328 | if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail) |
1329 | return should_fail(&fail_make_request, bio->bi_size); |
1330 | |
1331 | return 0; |
1332 | } |
1333 | |
1334 | static int __init fail_make_request_debugfs(void) |
1335 | { |
1336 | return init_fault_attr_dentries(&fail_make_request, |
1337 | "fail_make_request"); |
1338 | } |
1339 | |
1340 | late_initcall(fail_make_request_debugfs); |
1341 | |
1342 | #else /* CONFIG_FAIL_MAKE_REQUEST */ |
1343 | |
1344 | static inline int should_fail_request(struct bio *bio) |
1345 | { |
1346 | return 0; |
1347 | } |
1348 | |
1349 | #endif /* CONFIG_FAIL_MAKE_REQUEST */ |
1350 | |
1351 | /* |
1352 | * Check whether this bio extends beyond the end of the device. |
1353 | */ |
1354 | static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) |
1355 | { |
1356 | sector_t maxsector; |
1357 | |
1358 | if (!nr_sectors) |
1359 | return 0; |
1360 | |
1361 | /* Test device or partition size, when known. */ |
1362 | maxsector = bio->bi_bdev->bd_inode->i_size >> 9; |
1363 | if (maxsector) { |
1364 | sector_t sector = bio->bi_sector; |
1365 | |
1366 | if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { |
1367 | /* |
1368 | * This may well happen - the kernel calls bread() |
1369 | * without checking the size of the device, e.g., when |
1370 | * mounting a device. |
1371 | */ |
1372 | handle_bad_sector(bio); |
1373 | return 1; |
1374 | } |
1375 | } |
1376 | |
1377 | return 0; |
1378 | } |
1379 | |
1380 | /** |
1381 | * generic_make_request - hand a buffer to its device driver for I/O |
1382 | * @bio: The bio describing the location in memory and on the device. |
1383 | * |
1384 | * generic_make_request() is used to make I/O requests of block |
1385 | * devices. It is passed a &struct bio, which describes the I/O that needs |
1386 | * to be done. |
1387 | * |
1388 | * generic_make_request() does not return any status. The |
1389 | * success/failure status of the request, along with notification of |
1390 | * completion, is delivered asynchronously through the bio->bi_end_io |
1391 | * function described (one day) else where. |
1392 | * |
1393 | * The caller of generic_make_request must make sure that bi_io_vec |
1394 | * are set to describe the memory buffer, and that bi_dev and bi_sector are |
1395 | * set to describe the device address, and the |
1396 | * bi_end_io and optionally bi_private are set to describe how |
1397 | * completion notification should be signaled. |
1398 | * |
1399 | * generic_make_request and the drivers it calls may use bi_next if this |
1400 | * bio happens to be merged with someone else, and may change bi_dev and |
1401 | * bi_sector for remaps as it sees fit. So the values of these fields |
1402 | * should NOT be depended on after the call to generic_make_request. |
1403 | */ |
1404 | static inline void __generic_make_request(struct bio *bio) |
1405 | { |
1406 | struct request_queue *q; |
1407 | sector_t old_sector; |
1408 | int ret, nr_sectors = bio_sectors(bio); |
1409 | dev_t old_dev; |
1410 | int err = -EIO; |
1411 | |
1412 | might_sleep(); |
1413 | |
1414 | if (bio_check_eod(bio, nr_sectors)) |
1415 | goto end_io; |
1416 | |
1417 | /* |
1418 | * Resolve the mapping until finished. (drivers are |
1419 | * still free to implement/resolve their own stacking |
1420 | * by explicitly returning 0) |
1421 | * |
1422 | * NOTE: we don't repeat the blk_size check for each new device. |
1423 | * Stacking drivers are expected to know what they are doing. |
1424 | */ |
1425 | old_sector = -1; |
1426 | old_dev = 0; |
1427 | do { |
1428 | char b[BDEVNAME_SIZE]; |
1429 | |
1430 | q = bdev_get_queue(bio->bi_bdev); |
1431 | if (unlikely(!q)) { |
1432 | printk(KERN_ERR |
1433 | "generic_make_request: Trying to access " |
1434 | "nonexistent block-device %s (%Lu)\n", |
1435 | bdevname(bio->bi_bdev, b), |
1436 | (long long) bio->bi_sector); |
1437 | goto end_io; |
1438 | } |
1439 | |
1440 | if (unlikely(!bio_rw_flagged(bio, BIO_RW_DISCARD) && |
1441 | nr_sectors > queue_max_hw_sectors(q))) { |
1442 | printk(KERN_ERR "bio too big device %s (%u > %u)\n", |
1443 | bdevname(bio->bi_bdev, b), |
1444 | bio_sectors(bio), |
1445 | queue_max_hw_sectors(q)); |
1446 | goto end_io; |
1447 | } |
1448 | |
1449 | if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) |
1450 | goto end_io; |
1451 | |
1452 | if (should_fail_request(bio)) |
1453 | goto end_io; |
1454 | |
1455 | /* |
1456 | * If this device has partitions, remap block n |
1457 | * of partition p to block n+start(p) of the disk. |
1458 | */ |
1459 | blk_partition_remap(bio); |
1460 | |
1461 | if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) |
1462 | goto end_io; |
1463 | |
1464 | if (old_sector != -1) |
1465 | trace_block_remap(q, bio, old_dev, old_sector); |
1466 | |
1467 | old_sector = bio->bi_sector; |
1468 | old_dev = bio->bi_bdev->bd_dev; |
1469 | |
1470 | if (bio_check_eod(bio, nr_sectors)) |
1471 | goto end_io; |
1472 | |
1473 | if (bio_rw_flagged(bio, BIO_RW_DISCARD) && |
1474 | !blk_queue_discard(q)) { |
1475 | err = -EOPNOTSUPP; |
1476 | goto end_io; |
1477 | } |
1478 | |
1479 | trace_block_bio_queue(q, bio); |
1480 | |
1481 | ret = q->make_request_fn(q, bio); |
1482 | } while (ret); |
1483 | |
1484 | return; |
1485 | |
1486 | end_io: |
1487 | bio_endio(bio, err); |
1488 | } |
1489 | |
1490 | /* |
1491 | * We only want one ->make_request_fn to be active at a time, |
1492 | * else stack usage with stacked devices could be a problem. |
1493 | * So use current->bio_list to keep a list of requests |
1494 | * submited by a make_request_fn function. |
1495 | * current->bio_list is also used as a flag to say if |
1496 | * generic_make_request is currently active in this task or not. |
1497 | * If it is NULL, then no make_request is active. If it is non-NULL, |
1498 | * then a make_request is active, and new requests should be added |
1499 | * at the tail |
1500 | */ |
1501 | void generic_make_request(struct bio *bio) |
1502 | { |
1503 | struct bio_list bio_list_on_stack; |
1504 | |
1505 | if (current->bio_list) { |
1506 | /* make_request is active */ |
1507 | bio_list_add(current->bio_list, bio); |
1508 | return; |
1509 | } |
1510 | /* following loop may be a bit non-obvious, and so deserves some |
1511 | * explanation. |
1512 | * Before entering the loop, bio->bi_next is NULL (as all callers |
1513 | * ensure that) so we have a list with a single bio. |
1514 | * We pretend that we have just taken it off a longer list, so |
1515 | * we assign bio_list to a pointer to the bio_list_on_stack, |
1516 | * thus initialising the bio_list of new bios to be |
1517 | * added. __generic_make_request may indeed add some more bios |
1518 | * through a recursive call to generic_make_request. If it |
1519 | * did, we find a non-NULL value in bio_list and re-enter the loop |
1520 | * from the top. In this case we really did just take the bio |
1521 | * of the top of the list (no pretending) and so remove it from |
1522 | * bio_list, and call into __generic_make_request again. |
1523 | * |
1524 | * The loop was structured like this to make only one call to |
1525 | * __generic_make_request (which is important as it is large and |
1526 | * inlined) and to keep the structure simple. |
1527 | */ |
1528 | BUG_ON(bio->bi_next); |
1529 | bio_list_init(&bio_list_on_stack); |
1530 | current->bio_list = &bio_list_on_stack; |
1531 | do { |
1532 | __generic_make_request(bio); |
1533 | bio = bio_list_pop(current->bio_list); |
1534 | } while (bio); |
1535 | current->bio_list = NULL; /* deactivate */ |
1536 | } |
1537 | EXPORT_SYMBOL(generic_make_request); |
1538 | |
1539 | /** |
1540 | * submit_bio - submit a bio to the block device layer for I/O |
1541 | * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) |
1542 | * @bio: The &struct bio which describes the I/O |
1543 | * |
1544 | * submit_bio() is very similar in purpose to generic_make_request(), and |
1545 | * uses that function to do most of the work. Both are fairly rough |
1546 | * interfaces; @bio must be presetup and ready for I/O. |
1547 | * |
1548 | */ |
1549 | void submit_bio(int rw, struct bio *bio) |
1550 | { |
1551 | int count = bio_sectors(bio); |
1552 | |
1553 | bio->bi_rw |= rw; |
1554 | |
1555 | /* |
1556 | * If it's a regular read/write or a barrier with data attached, |
1557 | * go through the normal accounting stuff before submission. |
1558 | */ |
1559 | if (bio_has_data(bio)) { |
1560 | if (rw & WRITE) { |
1561 | count_vm_events(PGPGOUT, count); |
1562 | } else { |
1563 | task_io_account_read(bio->bi_size); |
1564 | count_vm_events(PGPGIN, count); |
1565 | } |
1566 | |
1567 | if (unlikely(block_dump)) { |
1568 | char b[BDEVNAME_SIZE]; |
1569 | printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n", |
1570 | current->comm, task_pid_nr(current), |
1571 | (rw & WRITE) ? "WRITE" : "READ", |
1572 | (unsigned long long)bio->bi_sector, |
1573 | bdevname(bio->bi_bdev, b)); |
1574 | } |
1575 | } |
1576 | |
1577 | generic_make_request(bio); |
1578 | } |
1579 | EXPORT_SYMBOL(submit_bio); |
1580 | |
1581 | /** |
1582 | * blk_rq_check_limits - Helper function to check a request for the queue limit |
1583 | * @q: the queue |
1584 | * @rq: the request being checked |
1585 | * |
1586 | * Description: |
1587 | * @rq may have been made based on weaker limitations of upper-level queues |
1588 | * in request stacking drivers, and it may violate the limitation of @q. |
1589 | * Since the block layer and the underlying device driver trust @rq |
1590 | * after it is inserted to @q, it should be checked against @q before |
1591 | * the insertion using this generic function. |
1592 | * |
1593 | * This function should also be useful for request stacking drivers |
1594 | * in some cases below, so export this fuction. |
1595 | * Request stacking drivers like request-based dm may change the queue |
1596 | * limits while requests are in the queue (e.g. dm's table swapping). |
1597 | * Such request stacking drivers should check those requests agaist |
1598 | * the new queue limits again when they dispatch those requests, |
1599 | * although such checkings are also done against the old queue limits |
1600 | * when submitting requests. |
1601 | */ |
1602 | int blk_rq_check_limits(struct request_queue *q, struct request *rq) |
1603 | { |
1604 | if (blk_rq_sectors(rq) > queue_max_sectors(q) || |
1605 | blk_rq_bytes(rq) > queue_max_hw_sectors(q) << 9) { |
1606 | printk(KERN_ERR "%s: over max size limit.\n", __func__); |
1607 | return -EIO; |
1608 | } |
1609 | |
1610 | /* |
1611 | * queue's settings related to segment counting like q->bounce_pfn |
1612 | * may differ from that of other stacking queues. |
1613 | * Recalculate it to check the request correctly on this queue's |
1614 | * limitation. |
1615 | */ |
1616 | blk_recalc_rq_segments(rq); |
1617 | if (rq->nr_phys_segments > queue_max_segments(q)) { |
1618 | printk(KERN_ERR "%s: over max segments limit.\n", __func__); |
1619 | return -EIO; |
1620 | } |
1621 | |
1622 | return 0; |
1623 | } |
1624 | EXPORT_SYMBOL_GPL(blk_rq_check_limits); |
1625 | |
1626 | /** |
1627 | * blk_insert_cloned_request - Helper for stacking drivers to submit a request |
1628 | * @q: the queue to submit the request |
1629 | * @rq: the request being queued |
1630 | */ |
1631 | int blk_insert_cloned_request(struct request_queue *q, struct request *rq) |
1632 | { |
1633 | unsigned long flags; |
1634 | |
1635 | if (blk_rq_check_limits(q, rq)) |
1636 | return -EIO; |
1637 | |
1638 | #ifdef CONFIG_FAIL_MAKE_REQUEST |
1639 | if (rq->rq_disk && rq->rq_disk->part0.make_it_fail && |
1640 | should_fail(&fail_make_request, blk_rq_bytes(rq))) |
1641 | return -EIO; |
1642 | #endif |
1643 | |
1644 | spin_lock_irqsave(q->queue_lock, flags); |
1645 | |
1646 | /* |
1647 | * Submitting request must be dequeued before calling this function |
1648 | * because it will be linked to another request_queue |
1649 | */ |
1650 | BUG_ON(blk_queued_rq(rq)); |
1651 | |
1652 | drive_stat_acct(rq, 1); |
1653 | __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); |
1654 | |
1655 | spin_unlock_irqrestore(q->queue_lock, flags); |
1656 | |
1657 | return 0; |
1658 | } |
1659 | EXPORT_SYMBOL_GPL(blk_insert_cloned_request); |
1660 | |
1661 | /** |
1662 | * blk_rq_err_bytes - determine number of bytes till the next failure boundary |
1663 | * @rq: request to examine |
1664 | * |
1665 | * Description: |
1666 | * A request could be merge of IOs which require different failure |
1667 | * handling. This function determines the number of bytes which |
1668 | * can be failed from the beginning of the request without |
1669 | * crossing into area which need to be retried further. |
1670 | * |
1671 | * Return: |
1672 | * The number of bytes to fail. |
1673 | * |
1674 | * Context: |
1675 | * queue_lock must be held. |
1676 | */ |
1677 | unsigned int blk_rq_err_bytes(const struct request *rq) |
1678 | { |
1679 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; |
1680 | unsigned int bytes = 0; |
1681 | struct bio *bio; |
1682 | |
1683 | if (!(rq->cmd_flags & REQ_MIXED_MERGE)) |
1684 | return blk_rq_bytes(rq); |
1685 | |
1686 | /* |
1687 | * Currently the only 'mixing' which can happen is between |
1688 | * different fastfail types. We can safely fail portions |
1689 | * which have all the failfast bits that the first one has - |
1690 | * the ones which are at least as eager to fail as the first |
1691 | * one. |
1692 | */ |
1693 | for (bio = rq->bio; bio; bio = bio->bi_next) { |
1694 | if ((bio->bi_rw & ff) != ff) |
1695 | break; |
1696 | bytes += bio->bi_size; |
1697 | } |
1698 | |
1699 | /* this could lead to infinite loop */ |
1700 | BUG_ON(blk_rq_bytes(rq) && !bytes); |
1701 | return bytes; |
1702 | } |
1703 | EXPORT_SYMBOL_GPL(blk_rq_err_bytes); |
1704 | |
1705 | static void blk_account_io_completion(struct request *req, unsigned int bytes) |
1706 | { |
1707 | if (blk_do_io_stat(req)) { |
1708 | const int rw = rq_data_dir(req); |
1709 | struct hd_struct *part; |
1710 | int cpu; |
1711 | |
1712 | cpu = part_stat_lock(); |
1713 | part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req)); |
1714 | part_stat_add(cpu, part, sectors[rw], bytes >> 9); |
1715 | part_stat_unlock(); |
1716 | } |
1717 | } |
1718 | |
1719 | static void blk_account_io_done(struct request *req) |
1720 | { |
1721 | /* |
1722 | * Account IO completion. bar_rq isn't accounted as a normal |
1723 | * IO on queueing nor completion. Accounting the containing |
1724 | * request is enough. |
1725 | */ |
1726 | if (blk_do_io_stat(req) && req != &req->q->bar_rq) { |
1727 | unsigned long duration = jiffies - req->start_time; |
1728 | const int rw = rq_data_dir(req); |
1729 | struct hd_struct *part; |
1730 | int cpu; |
1731 | |
1732 | cpu = part_stat_lock(); |
1733 | part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req)); |
1734 | |
1735 | part_stat_inc(cpu, part, ios[rw]); |
1736 | part_stat_add(cpu, part, ticks[rw], duration); |
1737 | part_round_stats(cpu, part); |
1738 | part_dec_in_flight(part, rw); |
1739 | |
1740 | part_stat_unlock(); |
1741 | } |
1742 | } |
1743 | |
1744 | /** |
1745 | * blk_peek_request - peek at the top of a request queue |
1746 | * @q: request queue to peek at |
1747 | * |
1748 | * Description: |
1749 | * Return the request at the top of @q. The returned request |
1750 | * should be started using blk_start_request() before LLD starts |
1751 | * processing it. |
1752 | * |
1753 | * Return: |
1754 | * Pointer to the request at the top of @q if available. Null |
1755 | * otherwise. |
1756 | * |
1757 | * Context: |
1758 | * queue_lock must be held. |
1759 | */ |
1760 | struct request *blk_peek_request(struct request_queue *q) |
1761 | { |
1762 | struct request *rq; |
1763 | int ret; |
1764 | |
1765 | while ((rq = __elv_next_request(q)) != NULL) { |
1766 | if (!(rq->cmd_flags & REQ_STARTED)) { |
1767 | /* |
1768 | * This is the first time the device driver |
1769 | * sees this request (possibly after |
1770 | * requeueing). Notify IO scheduler. |
1771 | */ |
1772 | if (blk_sorted_rq(rq)) |
1773 | elv_activate_rq(q, rq); |
1774 | |
1775 | /* |
1776 | * just mark as started even if we don't start |
1777 | * it, a request that has been delayed should |
1778 | * not be passed by new incoming requests |
1779 | */ |
1780 | rq->cmd_flags |= REQ_STARTED; |
1781 | trace_block_rq_issue(q, rq); |
1782 | } |
1783 | |
1784 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1785 | q->end_sector = rq_end_sector(rq); |
1786 | q->boundary_rq = NULL; |
1787 | } |
1788 | |
1789 | if (rq->cmd_flags & REQ_DONTPREP) |
1790 | break; |
1791 | |
1792 | if (q->dma_drain_size && blk_rq_bytes(rq)) { |
1793 | /* |
1794 | * make sure space for the drain appears we |
1795 | * know we can do this because max_hw_segments |
1796 | * has been adjusted to be one fewer than the |
1797 | * device can handle |
1798 | */ |
1799 | rq->nr_phys_segments++; |
1800 | } |
1801 | |
1802 | if (!q->prep_rq_fn) |
1803 | break; |
1804 | |
1805 | ret = q->prep_rq_fn(q, rq); |
1806 | if (ret == BLKPREP_OK) { |
1807 | break; |
1808 | } else if (ret == BLKPREP_DEFER) { |
1809 | /* |
1810 | * the request may have been (partially) prepped. |
1811 | * we need to keep this request in the front to |
1812 | * avoid resource deadlock. REQ_STARTED will |
1813 | * prevent other fs requests from passing this one. |
1814 | */ |
1815 | if (q->dma_drain_size && blk_rq_bytes(rq) && |
1816 | !(rq->cmd_flags & REQ_DONTPREP)) { |
1817 | /* |
1818 | * remove the space for the drain we added |
1819 | * so that we don't add it again |
1820 | */ |
1821 | --rq->nr_phys_segments; |
1822 | } |
1823 | |
1824 | rq = NULL; |
1825 | break; |
1826 | } else if (ret == BLKPREP_KILL) { |
1827 | rq->cmd_flags |= REQ_QUIET; |
1828 | /* |
1829 | * Mark this request as started so we don't trigger |
1830 | * any debug logic in the end I/O path. |
1831 | */ |
1832 | blk_start_request(rq); |
1833 | __blk_end_request_all(rq, -EIO); |
1834 | } else { |
1835 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); |
1836 | break; |
1837 | } |
1838 | } |
1839 | |
1840 | return rq; |
1841 | } |
1842 | EXPORT_SYMBOL(blk_peek_request); |
1843 | |
1844 | void blk_dequeue_request(struct request *rq) |
1845 | { |
1846 | struct request_queue *q = rq->q; |
1847 | |
1848 | BUG_ON(list_empty(&rq->queuelist)); |
1849 | BUG_ON(ELV_ON_HASH(rq)); |
1850 | |
1851 | list_del_init(&rq->queuelist); |
1852 | |
1853 | /* |
1854 | * the time frame between a request being removed from the lists |
1855 | * and to it is freed is accounted as io that is in progress at |
1856 | * the driver side. |
1857 | */ |
1858 | if (blk_account_rq(rq)) |
1859 | q->in_flight[rq_is_sync(rq)]++; |
1860 | } |
1861 | |
1862 | /** |
1863 | * blk_start_request - start request processing on the driver |
1864 | * @req: request to dequeue |
1865 | * |
1866 | * Description: |
1867 | * Dequeue @req and start timeout timer on it. This hands off the |
1868 | * request to the driver. |
1869 | * |
1870 | * Block internal functions which don't want to start timer should |
1871 | * call blk_dequeue_request(). |
1872 | * |
1873 | * Context: |
1874 | * queue_lock must be held. |
1875 | */ |
1876 | void blk_start_request(struct request *req) |
1877 | { |
1878 | blk_dequeue_request(req); |
1879 | |
1880 | /* |
1881 | * We are now handing the request to the hardware, initialize |
1882 | * resid_len to full count and add the timeout handler. |
1883 | */ |
1884 | req->resid_len = blk_rq_bytes(req); |
1885 | if (unlikely(blk_bidi_rq(req))) |
1886 | req->next_rq->resid_len = blk_rq_bytes(req->next_rq); |
1887 | |
1888 | blk_add_timer(req); |
1889 | } |
1890 | EXPORT_SYMBOL(blk_start_request); |
1891 | |
1892 | /** |
1893 | * blk_fetch_request - fetch a request from a request queue |
1894 | * @q: request queue to fetch a request from |
1895 | * |
1896 | * Description: |
1897 | * Return the request at the top of @q. The request is started on |
1898 | * return and LLD can start processing it immediately. |
1899 | * |
1900 | * Return: |
1901 | * Pointer to the request at the top of @q if available. Null |
1902 | * otherwise. |
1903 | * |
1904 | * Context: |
1905 | * queue_lock must be held. |
1906 | */ |
1907 | struct request *blk_fetch_request(struct request_queue *q) |
1908 | { |
1909 | struct request *rq; |
1910 | |
1911 | rq = blk_peek_request(q); |
1912 | if (rq) |
1913 | blk_start_request(rq); |
1914 | return rq; |
1915 | } |
1916 | EXPORT_SYMBOL(blk_fetch_request); |
1917 | |
1918 | /** |
1919 | * blk_update_request - Special helper function for request stacking drivers |
1920 | * @req: the request being processed |
1921 | * @error: %0 for success, < %0 for error |
1922 | * @nr_bytes: number of bytes to complete @req |
1923 | * |
1924 | * Description: |
1925 | * Ends I/O on a number of bytes attached to @req, but doesn't complete |
1926 | * the request structure even if @req doesn't have leftover. |
1927 | * If @req has leftover, sets it up for the next range of segments. |
1928 | * |
1929 | * This special helper function is only for request stacking drivers |
1930 | * (e.g. request-based dm) so that they can handle partial completion. |
1931 | * Actual device drivers should use blk_end_request instead. |
1932 | * |
1933 | * Passing the result of blk_rq_bytes() as @nr_bytes guarantees |
1934 | * %false return from this function. |
1935 | * |
1936 | * Return: |
1937 | * %false - this request doesn't have any more data |
1938 | * %true - this request has more data |
1939 | **/ |
1940 | bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) |
1941 | { |
1942 | int total_bytes, bio_nbytes, next_idx = 0; |
1943 | struct bio *bio; |
1944 | |
1945 | if (!req->bio) |
1946 | return false; |
1947 | |
1948 | trace_block_rq_complete(req->q, req); |
1949 | |
1950 | /* |
1951 | * For fs requests, rq is just carrier of independent bio's |
1952 | * and each partial completion should be handled separately. |
1953 | * Reset per-request error on each partial completion. |
1954 | * |
1955 | * TODO: tj: This is too subtle. It would be better to let |
1956 | * low level drivers do what they see fit. |
1957 | */ |
1958 | if (blk_fs_request(req)) |
1959 | req->errors = 0; |
1960 | |
1961 | if (error && (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET))) { |
1962 | printk(KERN_ERR "end_request: I/O error, dev %s, sector %llu\n", |
1963 | req->rq_disk ? req->rq_disk->disk_name : "?", |
1964 | (unsigned long long)blk_rq_pos(req)); |
1965 | } |
1966 | |
1967 | blk_account_io_completion(req, nr_bytes); |
1968 | |
1969 | total_bytes = bio_nbytes = 0; |
1970 | while ((bio = req->bio) != NULL) { |
1971 | int nbytes; |
1972 | |
1973 | if (nr_bytes >= bio->bi_size) { |
1974 | req->bio = bio->bi_next; |
1975 | nbytes = bio->bi_size; |
1976 | req_bio_endio(req, bio, nbytes, error); |
1977 | next_idx = 0; |
1978 | bio_nbytes = 0; |
1979 | } else { |
1980 | int idx = bio->bi_idx + next_idx; |
1981 | |
1982 | if (unlikely(idx >= bio->bi_vcnt)) { |
1983 | blk_dump_rq_flags(req, "__end_that"); |
1984 | printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n", |
1985 | __func__, idx, bio->bi_vcnt); |
1986 | break; |
1987 | } |
1988 | |
1989 | nbytes = bio_iovec_idx(bio, idx)->bv_len; |
1990 | BIO_BUG_ON(nbytes > bio->bi_size); |
1991 | |
1992 | /* |
1993 | * not a complete bvec done |
1994 | */ |
1995 | if (unlikely(nbytes > nr_bytes)) { |
1996 | bio_nbytes += nr_bytes; |
1997 | total_bytes += nr_bytes; |
1998 | break; |
1999 | } |
2000 | |
2001 | /* |
2002 | * advance to the next vector |
2003 | */ |
2004 | next_idx++; |
2005 | bio_nbytes += nbytes; |
2006 | } |
2007 | |
2008 | total_bytes += nbytes; |
2009 | nr_bytes -= nbytes; |
2010 | |
2011 | bio = req->bio; |
2012 | if (bio) { |
2013 | /* |
2014 | * end more in this run, or just return 'not-done' |
2015 | */ |
2016 | if (unlikely(nr_bytes <= 0)) |
2017 | break; |
2018 | } |
2019 | } |
2020 | |
2021 | /* |
2022 | * completely done |
2023 | */ |
2024 | if (!req->bio) { |
2025 | /* |
2026 | * Reset counters so that the request stacking driver |
2027 | * can find how many bytes remain in the request |
2028 | * later. |
2029 | */ |
2030 | req->__data_len = 0; |
2031 | return false; |
2032 | } |
2033 | |
2034 | /* |
2035 | * if the request wasn't completed, update state |
2036 | */ |
2037 | if (bio_nbytes) { |
2038 | req_bio_endio(req, bio, bio_nbytes, error); |
2039 | bio->bi_idx += next_idx; |
2040 | bio_iovec(bio)->bv_offset += nr_bytes; |
2041 | bio_iovec(bio)->bv_len -= nr_bytes; |
2042 | } |
2043 | |
2044 | req->__data_len -= total_bytes; |
2045 | req->buffer = bio_data(req->bio); |
2046 | |
2047 | /* update sector only for requests with clear definition of sector */ |
2048 | if (blk_fs_request(req) || blk_discard_rq(req)) |
2049 | req->__sector += total_bytes >> 9; |
2050 | |
2051 | /* mixed attributes always follow the first bio */ |
2052 | if (req->cmd_flags & REQ_MIXED_MERGE) { |
2053 | req->cmd_flags &= ~REQ_FAILFAST_MASK; |
2054 | req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK; |
2055 | } |
2056 | |
2057 | /* |
2058 | * If total number of sectors is less than the first segment |
2059 | * size, something has gone terribly wrong. |
2060 | */ |
2061 | if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { |
2062 | printk(KERN_ERR "blk: request botched\n"); |
2063 | req->__data_len = blk_rq_cur_bytes(req); |
2064 | } |
2065 | |
2066 | /* recalculate the number of segments */ |
2067 | blk_recalc_rq_segments(req); |
2068 | |
2069 | return true; |
2070 | } |
2071 | EXPORT_SYMBOL_GPL(blk_update_request); |
2072 | |
2073 | static bool blk_update_bidi_request(struct request *rq, int error, |
2074 | unsigned int nr_bytes, |
2075 | unsigned int bidi_bytes) |
2076 | { |
2077 | if (blk_update_request(rq, error, nr_bytes)) |
2078 | return true; |
2079 | |
2080 | /* Bidi request must be completed as a whole */ |
2081 | if (unlikely(blk_bidi_rq(rq)) && |
2082 | blk_update_request(rq->next_rq, error, bidi_bytes)) |
2083 | return true; |
2084 | |
2085 | add_disk_randomness(rq->rq_disk); |
2086 | |
2087 | return false; |
2088 | } |
2089 | |
2090 | /* |
2091 | * queue lock must be held |
2092 | */ |
2093 | static void blk_finish_request(struct request *req, int error) |
2094 | { |
2095 | if (blk_rq_tagged(req)) |
2096 | blk_queue_end_tag(req->q, req); |
2097 | |
2098 | BUG_ON(blk_queued_rq(req)); |
2099 | |
2100 | if (unlikely(laptop_mode) && blk_fs_request(req)) |
2101 | laptop_io_completion(); |
2102 | |
2103 | blk_delete_timer(req); |
2104 | |
2105 | blk_account_io_done(req); |
2106 | |
2107 | if (req->end_io) |
2108 | req->end_io(req, error); |
2109 | else { |
2110 | if (blk_bidi_rq(req)) |
2111 | __blk_put_request(req->next_rq->q, req->next_rq); |
2112 | |
2113 | __blk_put_request(req->q, req); |
2114 | } |
2115 | } |
2116 | |
2117 | /** |
2118 | * blk_end_bidi_request - Complete a bidi request |
2119 | * @rq: the request to complete |
2120 | * @error: %0 for success, < %0 for error |
2121 | * @nr_bytes: number of bytes to complete @rq |
2122 | * @bidi_bytes: number of bytes to complete @rq->next_rq |
2123 | * |
2124 | * Description: |
2125 | * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. |
2126 | * Drivers that supports bidi can safely call this member for any |
2127 | * type of request, bidi or uni. In the later case @bidi_bytes is |
2128 | * just ignored. |
2129 | * |
2130 | * Return: |
2131 | * %false - we are done with this request |
2132 | * %true - still buffers pending for this request |
2133 | **/ |
2134 | static bool blk_end_bidi_request(struct request *rq, int error, |
2135 | unsigned int nr_bytes, unsigned int bidi_bytes) |
2136 | { |
2137 | struct request_queue *q = rq->q; |
2138 | unsigned long flags; |
2139 | |
2140 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
2141 | return true; |
2142 | |
2143 | spin_lock_irqsave(q->queue_lock, flags); |
2144 | blk_finish_request(rq, error); |
2145 | spin_unlock_irqrestore(q->queue_lock, flags); |
2146 | |
2147 | return false; |
2148 | } |
2149 | |
2150 | /** |
2151 | * __blk_end_bidi_request - Complete a bidi request with queue lock held |
2152 | * @rq: the request to complete |
2153 | * @error: %0 for success, < %0 for error |
2154 | * @nr_bytes: number of bytes to complete @rq |
2155 | * @bidi_bytes: number of bytes to complete @rq->next_rq |
2156 | * |
2157 | * Description: |
2158 | * Identical to blk_end_bidi_request() except that queue lock is |
2159 | * assumed to be locked on entry and remains so on return. |
2160 | * |
2161 | * Return: |
2162 | * %false - we are done with this request |
2163 | * %true - still buffers pending for this request |
2164 | **/ |
2165 | static bool __blk_end_bidi_request(struct request *rq, int error, |
2166 | unsigned int nr_bytes, unsigned int bidi_bytes) |
2167 | { |
2168 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
2169 | return true; |
2170 | |
2171 | blk_finish_request(rq, error); |
2172 | |
2173 | return false; |
2174 | } |
2175 | |
2176 | /** |
2177 | * blk_end_request - Helper function for drivers to complete the request. |
2178 | * @rq: the request being processed |
2179 | * @error: %0 for success, < %0 for error |
2180 | * @nr_bytes: number of bytes to complete |
2181 | * |
2182 | * Description: |
2183 | * Ends I/O on a number of bytes attached to @rq. |
2184 | * If @rq has leftover, sets it up for the next range of segments. |
2185 | * |
2186 | * Return: |
2187 | * %false - we are done with this request |
2188 | * %true - still buffers pending for this request |
2189 | **/ |
2190 | bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
2191 | { |
2192 | return blk_end_bidi_request(rq, error, nr_bytes, 0); |
2193 | } |
2194 | EXPORT_SYMBOL(blk_end_request); |
2195 | |
2196 | /** |
2197 | * blk_end_request_all - Helper function for drives to finish the request. |
2198 | * @rq: the request to finish |
2199 | * @error: %0 for success, < %0 for error |
2200 | * |
2201 | * Description: |
2202 | * Completely finish @rq. |
2203 | */ |
2204 | void blk_end_request_all(struct request *rq, int error) |
2205 | { |
2206 | bool pending; |
2207 | unsigned int bidi_bytes = 0; |
2208 | |
2209 | if (unlikely(blk_bidi_rq(rq))) |
2210 | bidi_bytes = blk_rq_bytes(rq->next_rq); |
2211 | |
2212 | pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); |
2213 | BUG_ON(pending); |
2214 | } |
2215 | EXPORT_SYMBOL(blk_end_request_all); |
2216 | |
2217 | /** |
2218 | * blk_end_request_cur - Helper function to finish the current request chunk. |
2219 | * @rq: the request to finish the current chunk for |
2220 | * @error: %0 for success, < %0 for error |
2221 | * |
2222 | * Description: |
2223 | * Complete the current consecutively mapped chunk from @rq. |
2224 | * |
2225 | * Return: |
2226 | * %false - we are done with this request |
2227 | * %true - still buffers pending for this request |
2228 | */ |
2229 | bool blk_end_request_cur(struct request *rq, int error) |
2230 | { |
2231 | return blk_end_request(rq, error, blk_rq_cur_bytes(rq)); |
2232 | } |
2233 | EXPORT_SYMBOL(blk_end_request_cur); |
2234 | |
2235 | /** |
2236 | * blk_end_request_err - Finish a request till the next failure boundary. |
2237 | * @rq: the request to finish till the next failure boundary for |
2238 | * @error: must be negative errno |
2239 | * |
2240 | * Description: |
2241 | * Complete @rq till the next failure boundary. |
2242 | * |
2243 | * Return: |
2244 | * %false - we are done with this request |
2245 | * %true - still buffers pending for this request |
2246 | */ |
2247 | bool blk_end_request_err(struct request *rq, int error) |
2248 | { |
2249 | WARN_ON(error >= 0); |
2250 | return blk_end_request(rq, error, blk_rq_err_bytes(rq)); |
2251 | } |
2252 | EXPORT_SYMBOL_GPL(blk_end_request_err); |
2253 | |
2254 | /** |
2255 | * __blk_end_request - Helper function for drivers to complete the request. |
2256 | * @rq: the request being processed |
2257 | * @error: %0 for success, < %0 for error |
2258 | * @nr_bytes: number of bytes to complete |
2259 | * |
2260 | * Description: |
2261 | * Must be called with queue lock held unlike blk_end_request(). |
2262 | * |
2263 | * Return: |
2264 | * %false - we are done with this request |
2265 | * %true - still buffers pending for this request |
2266 | **/ |
2267 | bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
2268 | { |
2269 | return __blk_end_bidi_request(rq, error, nr_bytes, 0); |
2270 | } |
2271 | EXPORT_SYMBOL(__blk_end_request); |
2272 | |
2273 | /** |
2274 | * __blk_end_request_all - Helper function for drives to finish the request. |
2275 | * @rq: the request to finish |
2276 | * @error: %0 for success, < %0 for error |
2277 | * |
2278 | * Description: |
2279 | * Completely finish @rq. Must be called with queue lock held. |
2280 | */ |
2281 | void __blk_end_request_all(struct request *rq, int error) |
2282 | { |
2283 | bool pending; |
2284 | unsigned int bidi_bytes = 0; |
2285 | |
2286 | if (unlikely(blk_bidi_rq(rq))) |
2287 | bidi_bytes = blk_rq_bytes(rq->next_rq); |
2288 | |
2289 | pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); |
2290 | BUG_ON(pending); |
2291 | } |
2292 | EXPORT_SYMBOL(__blk_end_request_all); |
2293 | |
2294 | /** |
2295 | * __blk_end_request_cur - Helper function to finish the current request chunk. |
2296 | * @rq: the request to finish the current chunk for |
2297 | * @error: %0 for success, < %0 for error |
2298 | * |
2299 | * Description: |
2300 | * Complete the current consecutively mapped chunk from @rq. Must |
2301 | * be called with queue lock held. |
2302 | * |
2303 | * Return: |
2304 | * %false - we are done with this request |
2305 | * %true - still buffers pending for this request |
2306 | */ |
2307 | bool __blk_end_request_cur(struct request *rq, int error) |
2308 | { |
2309 | return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); |
2310 | } |
2311 | EXPORT_SYMBOL(__blk_end_request_cur); |
2312 | |
2313 | /** |
2314 | * __blk_end_request_err - Finish a request till the next failure boundary. |
2315 | * @rq: the request to finish till the next failure boundary for |
2316 | * @error: must be negative errno |
2317 | * |
2318 | * Description: |
2319 | * Complete @rq till the next failure boundary. Must be called |
2320 | * with queue lock held. |
2321 | * |
2322 | * Return: |
2323 | * %false - we are done with this request |
2324 | * %true - still buffers pending for this request |
2325 | */ |
2326 | bool __blk_end_request_err(struct request *rq, int error) |
2327 | { |
2328 | WARN_ON(error >= 0); |
2329 | return __blk_end_request(rq, error, blk_rq_err_bytes(rq)); |
2330 | } |
2331 | EXPORT_SYMBOL_GPL(__blk_end_request_err); |
2332 | |
2333 | void blk_rq_bio_prep(struct request_queue *q, struct request *rq, |
2334 | struct bio *bio) |
2335 | { |
2336 | /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */ |
2337 | rq->cmd_flags |= bio->bi_rw & REQ_RW; |
2338 | |
2339 | if (bio_has_data(bio)) { |
2340 | rq->nr_phys_segments = bio_phys_segments(q, bio); |
2341 | rq->buffer = bio_data(bio); |
2342 | } |
2343 | rq->__data_len = bio->bi_size; |
2344 | rq->bio = rq->biotail = bio; |
2345 | |
2346 | if (bio->bi_bdev) |
2347 | rq->rq_disk = bio->bi_bdev->bd_disk; |
2348 | } |
2349 | |
2350 | #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE |
2351 | /** |
2352 | * rq_flush_dcache_pages - Helper function to flush all pages in a request |
2353 | * @rq: the request to be flushed |
2354 | * |
2355 | * Description: |
2356 | * Flush all pages in @rq. |
2357 | */ |
2358 | void rq_flush_dcache_pages(struct request *rq) |
2359 | { |
2360 | struct req_iterator iter; |
2361 | struct bio_vec *bvec; |
2362 | |
2363 | rq_for_each_segment(bvec, rq, iter) |
2364 | flush_dcache_page(bvec->bv_page); |
2365 | } |
2366 | EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); |
2367 | #endif |
2368 | |
2369 | /** |
2370 | * blk_lld_busy - Check if underlying low-level drivers of a device are busy |
2371 | * @q : the queue of the device being checked |
2372 | * |
2373 | * Description: |
2374 | * Check if underlying low-level drivers of a device are busy. |
2375 | * If the drivers want to export their busy state, they must set own |
2376 | * exporting function using blk_queue_lld_busy() first. |
2377 | * |
2378 | * Basically, this function is used only by request stacking drivers |
2379 | * to stop dispatching requests to underlying devices when underlying |
2380 | * devices are busy. This behavior helps more I/O merging on the queue |
2381 | * of the request stacking driver and prevents I/O throughput regression |
2382 | * on burst I/O load. |
2383 | * |
2384 | * Return: |
2385 | * 0 - Not busy (The request stacking driver should dispatch request) |
2386 | * 1 - Busy (The request stacking driver should stop dispatching request) |
2387 | */ |
2388 | int blk_lld_busy(struct request_queue *q) |
2389 | { |
2390 | if (q->lld_busy_fn) |
2391 | return q->lld_busy_fn(q); |
2392 | |
2393 | return 0; |
2394 | } |
2395 | EXPORT_SYMBOL_GPL(blk_lld_busy); |
2396 | |
2397 | /** |
2398 | * blk_rq_unprep_clone - Helper function to free all bios in a cloned request |
2399 | * @rq: the clone request to be cleaned up |
2400 | * |
2401 | * Description: |
2402 | * Free all bios in @rq for a cloned request. |
2403 | */ |
2404 | void blk_rq_unprep_clone(struct request *rq) |
2405 | { |
2406 | struct bio *bio; |
2407 | |
2408 | while ((bio = rq->bio) != NULL) { |
2409 | rq->bio = bio->bi_next; |
2410 | |
2411 | bio_put(bio); |
2412 | } |
2413 | } |
2414 | EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); |
2415 | |
2416 | /* |
2417 | * Copy attributes of the original request to the clone request. |
2418 | * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied. |
2419 | */ |
2420 | static void __blk_rq_prep_clone(struct request *dst, struct request *src) |
2421 | { |
2422 | dst->cpu = src->cpu; |
2423 | dst->cmd_flags = (rq_data_dir(src) | REQ_NOMERGE); |
2424 | dst->cmd_type = src->cmd_type; |
2425 | dst->__sector = blk_rq_pos(src); |
2426 | dst->__data_len = blk_rq_bytes(src); |
2427 | dst->nr_phys_segments = src->nr_phys_segments; |
2428 | dst->ioprio = src->ioprio; |
2429 | dst->extra_len = src->extra_len; |
2430 | } |
2431 | |
2432 | /** |
2433 | * blk_rq_prep_clone - Helper function to setup clone request |
2434 | * @rq: the request to be setup |
2435 | * @rq_src: original request to be cloned |
2436 | * @bs: bio_set that bios for clone are allocated from |
2437 | * @gfp_mask: memory allocation mask for bio |
2438 | * @bio_ctr: setup function to be called for each clone bio. |
2439 | * Returns %0 for success, non %0 for failure. |
2440 | * @data: private data to be passed to @bio_ctr |
2441 | * |
2442 | * Description: |
2443 | * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. |
2444 | * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense) |
2445 | * are not copied, and copying such parts is the caller's responsibility. |
2446 | * Also, pages which the original bios are pointing to are not copied |
2447 | * and the cloned bios just point same pages. |
2448 | * So cloned bios must be completed before original bios, which means |
2449 | * the caller must complete @rq before @rq_src. |
2450 | */ |
2451 | int blk_rq_prep_clone(struct request *rq, struct request *rq_src, |
2452 | struct bio_set *bs, gfp_t gfp_mask, |
2453 | int (*bio_ctr)(struct bio *, struct bio *, void *), |
2454 | void *data) |
2455 | { |
2456 | struct bio *bio, *bio_src; |
2457 | |
2458 | if (!bs) |
2459 | bs = fs_bio_set; |
2460 | |
2461 | blk_rq_init(NULL, rq); |
2462 | |
2463 | __rq_for_each_bio(bio_src, rq_src) { |
2464 | bio = bio_alloc_bioset(gfp_mask, bio_src->bi_max_vecs, bs); |
2465 | if (!bio) |
2466 | goto free_and_out; |
2467 | |
2468 | __bio_clone(bio, bio_src); |
2469 | |
2470 | if (bio_integrity(bio_src) && |
2471 | bio_integrity_clone(bio, bio_src, gfp_mask, bs)) |
2472 | goto free_and_out; |
2473 | |
2474 | if (bio_ctr && bio_ctr(bio, bio_src, data)) |
2475 | goto free_and_out; |
2476 | |
2477 | if (rq->bio) { |
2478 | rq->biotail->bi_next = bio; |
2479 | rq->biotail = bio; |
2480 | } else |
2481 | rq->bio = rq->biotail = bio; |
2482 | } |
2483 | |
2484 | __blk_rq_prep_clone(rq, rq_src); |
2485 | |
2486 | return 0; |
2487 | |
2488 | free_and_out: |
2489 | if (bio) |
2490 | bio_free(bio, bs); |
2491 | blk_rq_unprep_clone(rq); |
2492 | |
2493 | return -ENOMEM; |
2494 | } |
2495 | EXPORT_SYMBOL_GPL(blk_rq_prep_clone); |
2496 | |
2497 | int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) |
2498 | { |
2499 | return queue_work(kblockd_workqueue, work); |
2500 | } |
2501 | EXPORT_SYMBOL(kblockd_schedule_work); |
2502 | |
2503 | int __init blk_dev_init(void) |
2504 | { |
2505 | BUILD_BUG_ON(__REQ_NR_BITS > 8 * |
2506 | sizeof(((struct request *)0)->cmd_flags)); |
2507 | |
2508 | kblockd_workqueue = create_workqueue("kblockd"); |
2509 | if (!kblockd_workqueue) |
2510 | panic("Failed to create kblockd\n"); |
2511 | |
2512 | request_cachep = kmem_cache_create("blkdev_requests", |
2513 | sizeof(struct request), 0, SLAB_PANIC, NULL); |
2514 | |
2515 | blk_requestq_cachep = kmem_cache_create("blkdev_queue", |
2516 | sizeof(struct request_queue), 0, SLAB_PANIC, NULL); |
2517 | |
2518 | return 0; |
2519 | } |
2520 | |
2521 |
Branches:
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javiroman/ks7010
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9