Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
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> | |
6728cb0e JA |
6 | * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> |
7 | * - July2000 | |
1da177e4 LT |
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 | */ | |
1da177e4 LT |
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> | |
1da177e4 LT |
24 | #include <linux/completion.h> |
25 | #include <linux/slab.h> | |
26 | #include <linux/swap.h> | |
27 | #include <linux/writeback.h> | |
faccbd4b | 28 | #include <linux/task_io_accounting_ops.h> |
c17bb495 | 29 | #include <linux/fault-inject.h> |
73c10101 | 30 | #include <linux/list_sort.h> |
55782138 LZ |
31 | |
32 | #define CREATE_TRACE_POINTS | |
33 | #include <trace/events/block.h> | |
1da177e4 | 34 | |
8324aa91 JA |
35 | #include "blk.h" |
36 | ||
d07335e5 | 37 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); |
b0da3f0d | 38 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); |
55782138 | 39 | EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); |
0bfc2455 | 40 | |
165125e1 | 41 | static int __make_request(struct request_queue *q, struct bio *bio); |
1da177e4 LT |
42 | |
43 | /* | |
44 | * For the allocated request tables | |
45 | */ | |
5ece6c52 | 46 | static struct kmem_cache *request_cachep; |
1da177e4 LT |
47 | |
48 | /* | |
49 | * For queue allocation | |
50 | */ | |
6728cb0e | 51 | struct kmem_cache *blk_requestq_cachep; |
1da177e4 | 52 | |
1da177e4 LT |
53 | /* |
54 | * Controlling structure to kblockd | |
55 | */ | |
ff856bad | 56 | static struct workqueue_struct *kblockd_workqueue; |
1da177e4 | 57 | |
26b8256e JA |
58 | static void drive_stat_acct(struct request *rq, int new_io) |
59 | { | |
28f13702 | 60 | struct hd_struct *part; |
26b8256e | 61 | int rw = rq_data_dir(rq); |
c9959059 | 62 | int cpu; |
26b8256e | 63 | |
c2553b58 | 64 | if (!blk_do_io_stat(rq)) |
26b8256e JA |
65 | return; |
66 | ||
074a7aca | 67 | cpu = part_stat_lock(); |
c9959059 | 68 | |
09e099d4 JM |
69 | if (!new_io) { |
70 | part = rq->part; | |
074a7aca | 71 | part_stat_inc(cpu, part, merges[rw]); |
09e099d4 JM |
72 | } else { |
73 | part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); | |
6c23a968 | 74 | if (!hd_struct_try_get(part)) { |
09e099d4 JM |
75 | /* |
76 | * The partition is already being removed, | |
77 | * the request will be accounted on the disk only | |
78 | * | |
79 | * We take a reference on disk->part0 although that | |
80 | * partition will never be deleted, so we can treat | |
81 | * it as any other partition. | |
82 | */ | |
83 | part = &rq->rq_disk->part0; | |
6c23a968 | 84 | hd_struct_get(part); |
09e099d4 | 85 | } |
074a7aca | 86 | part_round_stats(cpu, part); |
316d315b | 87 | part_inc_in_flight(part, rw); |
09e099d4 | 88 | rq->part = part; |
26b8256e | 89 | } |
e71bf0d0 | 90 | |
074a7aca | 91 | part_stat_unlock(); |
26b8256e JA |
92 | } |
93 | ||
8324aa91 | 94 | void blk_queue_congestion_threshold(struct request_queue *q) |
1da177e4 LT |
95 | { |
96 | int nr; | |
97 | ||
98 | nr = q->nr_requests - (q->nr_requests / 8) + 1; | |
99 | if (nr > q->nr_requests) | |
100 | nr = q->nr_requests; | |
101 | q->nr_congestion_on = nr; | |
102 | ||
103 | nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; | |
104 | if (nr < 1) | |
105 | nr = 1; | |
106 | q->nr_congestion_off = nr; | |
107 | } | |
108 | ||
1da177e4 LT |
109 | /** |
110 | * blk_get_backing_dev_info - get the address of a queue's backing_dev_info | |
111 | * @bdev: device | |
112 | * | |
113 | * Locates the passed device's request queue and returns the address of its | |
114 | * backing_dev_info | |
115 | * | |
116 | * Will return NULL if the request queue cannot be located. | |
117 | */ | |
118 | struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) | |
119 | { | |
120 | struct backing_dev_info *ret = NULL; | |
165125e1 | 121 | struct request_queue *q = bdev_get_queue(bdev); |
1da177e4 LT |
122 | |
123 | if (q) | |
124 | ret = &q->backing_dev_info; | |
125 | return ret; | |
126 | } | |
1da177e4 LT |
127 | EXPORT_SYMBOL(blk_get_backing_dev_info); |
128 | ||
2a4aa30c | 129 | void blk_rq_init(struct request_queue *q, struct request *rq) |
1da177e4 | 130 | { |
1afb20f3 FT |
131 | memset(rq, 0, sizeof(*rq)); |
132 | ||
1da177e4 | 133 | INIT_LIST_HEAD(&rq->queuelist); |
242f9dcb | 134 | INIT_LIST_HEAD(&rq->timeout_list); |
c7c22e4d | 135 | rq->cpu = -1; |
63a71386 | 136 | rq->q = q; |
a2dec7b3 | 137 | rq->__sector = (sector_t) -1; |
2e662b65 JA |
138 | INIT_HLIST_NODE(&rq->hash); |
139 | RB_CLEAR_NODE(&rq->rb_node); | |
d7e3c324 | 140 | rq->cmd = rq->__cmd; |
e2494e1b | 141 | rq->cmd_len = BLK_MAX_CDB; |
63a71386 | 142 | rq->tag = -1; |
1da177e4 | 143 | rq->ref_count = 1; |
b243ddcb | 144 | rq->start_time = jiffies; |
9195291e | 145 | set_start_time_ns(rq); |
09e099d4 | 146 | rq->part = NULL; |
1da177e4 | 147 | } |
2a4aa30c | 148 | EXPORT_SYMBOL(blk_rq_init); |
1da177e4 | 149 | |
5bb23a68 N |
150 | static void req_bio_endio(struct request *rq, struct bio *bio, |
151 | unsigned int nbytes, int error) | |
1da177e4 | 152 | { |
143a87f4 TH |
153 | if (error) |
154 | clear_bit(BIO_UPTODATE, &bio->bi_flags); | |
155 | else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) | |
156 | error = -EIO; | |
797e7dbb | 157 | |
143a87f4 TH |
158 | if (unlikely(nbytes > bio->bi_size)) { |
159 | printk(KERN_ERR "%s: want %u bytes done, %u left\n", | |
160 | __func__, nbytes, bio->bi_size); | |
161 | nbytes = bio->bi_size; | |
5bb23a68 | 162 | } |
797e7dbb | 163 | |
143a87f4 TH |
164 | if (unlikely(rq->cmd_flags & REQ_QUIET)) |
165 | set_bit(BIO_QUIET, &bio->bi_flags); | |
08bafc03 | 166 | |
143a87f4 TH |
167 | bio->bi_size -= nbytes; |
168 | bio->bi_sector += (nbytes >> 9); | |
7ba1ba12 | 169 | |
143a87f4 TH |
170 | if (bio_integrity(bio)) |
171 | bio_integrity_advance(bio, nbytes); | |
7ba1ba12 | 172 | |
143a87f4 TH |
173 | /* don't actually finish bio if it's part of flush sequence */ |
174 | if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ)) | |
175 | bio_endio(bio, error); | |
1da177e4 | 176 | } |
1da177e4 | 177 | |
1da177e4 LT |
178 | void blk_dump_rq_flags(struct request *rq, char *msg) |
179 | { | |
180 | int bit; | |
181 | ||
6728cb0e | 182 | printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg, |
4aff5e23 JA |
183 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, |
184 | rq->cmd_flags); | |
1da177e4 | 185 | |
83096ebf TH |
186 | printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", |
187 | (unsigned long long)blk_rq_pos(rq), | |
188 | blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); | |
731ec497 | 189 | printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n", |
2e46e8b2 | 190 | rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq)); |
1da177e4 | 191 | |
33659ebb | 192 | if (rq->cmd_type == REQ_TYPE_BLOCK_PC) { |
6728cb0e | 193 | printk(KERN_INFO " cdb: "); |
d34c87e4 | 194 | for (bit = 0; bit < BLK_MAX_CDB; bit++) |
1da177e4 LT |
195 | printk("%02x ", rq->cmd[bit]); |
196 | printk("\n"); | |
197 | } | |
198 | } | |
1da177e4 LT |
199 | EXPORT_SYMBOL(blk_dump_rq_flags); |
200 | ||
3cca6dc1 | 201 | static void blk_delay_work(struct work_struct *work) |
1da177e4 | 202 | { |
3cca6dc1 | 203 | struct request_queue *q; |
1da177e4 | 204 | |
3cca6dc1 JA |
205 | q = container_of(work, struct request_queue, delay_work.work); |
206 | spin_lock_irq(q->queue_lock); | |
4c63f564 | 207 | __blk_run_queue(q, false); |
3cca6dc1 | 208 | spin_unlock_irq(q->queue_lock); |
1da177e4 | 209 | } |
1da177e4 LT |
210 | |
211 | /** | |
3cca6dc1 JA |
212 | * blk_delay_queue - restart queueing after defined interval |
213 | * @q: The &struct request_queue in question | |
214 | * @msecs: Delay in msecs | |
1da177e4 LT |
215 | * |
216 | * Description: | |
3cca6dc1 JA |
217 | * Sometimes queueing needs to be postponed for a little while, to allow |
218 | * resources to come back. This function will make sure that queueing is | |
219 | * restarted around the specified time. | |
220 | */ | |
221 | void blk_delay_queue(struct request_queue *q, unsigned long msecs) | |
2ad8b1ef | 222 | { |
3cca6dc1 | 223 | schedule_delayed_work(&q->delay_work, msecs_to_jiffies(msecs)); |
2ad8b1ef | 224 | } |
3cca6dc1 | 225 | EXPORT_SYMBOL(blk_delay_queue); |
2ad8b1ef | 226 | |
1da177e4 LT |
227 | /** |
228 | * blk_start_queue - restart a previously stopped queue | |
165125e1 | 229 | * @q: The &struct request_queue in question |
1da177e4 LT |
230 | * |
231 | * Description: | |
232 | * blk_start_queue() will clear the stop flag on the queue, and call | |
233 | * the request_fn for the queue if it was in a stopped state when | |
234 | * entered. Also see blk_stop_queue(). Queue lock must be held. | |
235 | **/ | |
165125e1 | 236 | void blk_start_queue(struct request_queue *q) |
1da177e4 | 237 | { |
a038e253 PBG |
238 | WARN_ON(!irqs_disabled()); |
239 | ||
75ad23bc | 240 | queue_flag_clear(QUEUE_FLAG_STOPPED, q); |
1654e741 | 241 | __blk_run_queue(q, false); |
1da177e4 | 242 | } |
1da177e4 LT |
243 | EXPORT_SYMBOL(blk_start_queue); |
244 | ||
245 | /** | |
246 | * blk_stop_queue - stop a queue | |
165125e1 | 247 | * @q: The &struct request_queue in question |
1da177e4 LT |
248 | * |
249 | * Description: | |
250 | * The Linux block layer assumes that a block driver will consume all | |
251 | * entries on the request queue when the request_fn strategy is called. | |
252 | * Often this will not happen, because of hardware limitations (queue | |
253 | * depth settings). If a device driver gets a 'queue full' response, | |
254 | * or if it simply chooses not to queue more I/O at one point, it can | |
255 | * call this function to prevent the request_fn from being called until | |
256 | * the driver has signalled it's ready to go again. This happens by calling | |
257 | * blk_start_queue() to restart queue operations. Queue lock must be held. | |
258 | **/ | |
165125e1 | 259 | void blk_stop_queue(struct request_queue *q) |
1da177e4 | 260 | { |
ad3d9d7e | 261 | __cancel_delayed_work(&q->delay_work); |
75ad23bc | 262 | queue_flag_set(QUEUE_FLAG_STOPPED, q); |
1da177e4 LT |
263 | } |
264 | EXPORT_SYMBOL(blk_stop_queue); | |
265 | ||
266 | /** | |
267 | * blk_sync_queue - cancel any pending callbacks on a queue | |
268 | * @q: the queue | |
269 | * | |
270 | * Description: | |
271 | * The block layer may perform asynchronous callback activity | |
272 | * on a queue, such as calling the unplug function after a timeout. | |
273 | * A block device may call blk_sync_queue to ensure that any | |
274 | * such activity is cancelled, thus allowing it to release resources | |
59c51591 | 275 | * that the callbacks might use. The caller must already have made sure |
1da177e4 LT |
276 | * that its ->make_request_fn will not re-add plugging prior to calling |
277 | * this function. | |
278 | * | |
da527770 VG |
279 | * This function does not cancel any asynchronous activity arising |
280 | * out of elevator or throttling code. That would require elevaotor_exit() | |
281 | * and blk_throtl_exit() to be called with queue lock initialized. | |
282 | * | |
1da177e4 LT |
283 | */ |
284 | void blk_sync_queue(struct request_queue *q) | |
285 | { | |
70ed28b9 | 286 | del_timer_sync(&q->timeout); |
3cca6dc1 | 287 | cancel_delayed_work_sync(&q->delay_work); |
1da177e4 LT |
288 | } |
289 | EXPORT_SYMBOL(blk_sync_queue); | |
290 | ||
291 | /** | |
80a4b58e | 292 | * __blk_run_queue - run a single device queue |
1da177e4 | 293 | * @q: The queue to run |
1654e741 | 294 | * @force_kblockd: Don't run @q->request_fn directly. Use kblockd. |
80a4b58e JA |
295 | * |
296 | * Description: | |
297 | * See @blk_run_queue. This variant must be called with the queue lock | |
298 | * held and interrupts disabled. | |
299 | * | |
1da177e4 | 300 | */ |
1654e741 | 301 | void __blk_run_queue(struct request_queue *q, bool force_kblockd) |
1da177e4 | 302 | { |
a538cd03 TH |
303 | if (unlikely(blk_queue_stopped(q))) |
304 | return; | |
305 | ||
dac07ec1 JA |
306 | /* |
307 | * Only recurse once to avoid overrunning the stack, let the unplug | |
308 | * handling reinvoke the handler shortly if we already got there. | |
309 | */ | |
1654e741 | 310 | if (!force_kblockd && !queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { |
a538cd03 TH |
311 | q->request_fn(q); |
312 | queue_flag_clear(QUEUE_FLAG_REENTER, q); | |
7eaceacc JA |
313 | } else |
314 | queue_delayed_work(kblockd_workqueue, &q->delay_work, 0); | |
75ad23bc NP |
315 | } |
316 | EXPORT_SYMBOL(__blk_run_queue); | |
dac07ec1 | 317 | |
75ad23bc NP |
318 | /** |
319 | * blk_run_queue - run a single device queue | |
320 | * @q: The queue to run | |
80a4b58e JA |
321 | * |
322 | * Description: | |
323 | * Invoke request handling on this queue, if it has pending work to do. | |
a7f55792 | 324 | * May be used to restart queueing when a request has completed. |
75ad23bc NP |
325 | */ |
326 | void blk_run_queue(struct request_queue *q) | |
327 | { | |
328 | unsigned long flags; | |
329 | ||
330 | spin_lock_irqsave(q->queue_lock, flags); | |
1654e741 | 331 | __blk_run_queue(q, false); |
1da177e4 LT |
332 | spin_unlock_irqrestore(q->queue_lock, flags); |
333 | } | |
334 | EXPORT_SYMBOL(blk_run_queue); | |
335 | ||
165125e1 | 336 | void blk_put_queue(struct request_queue *q) |
483f4afc AV |
337 | { |
338 | kobject_put(&q->kobj); | |
339 | } | |
483f4afc | 340 | |
c94a96ac VG |
341 | /* |
342 | * Note: If a driver supplied the queue lock, it should not zap that lock | |
343 | * unexpectedly as some queue cleanup components like elevator_exit() and | |
344 | * blk_throtl_exit() need queue lock. | |
345 | */ | |
6728cb0e | 346 | void blk_cleanup_queue(struct request_queue *q) |
483f4afc | 347 | { |
e3335de9 JA |
348 | /* |
349 | * We know we have process context here, so we can be a little | |
350 | * cautious and ensure that pending block actions on this device | |
351 | * are done before moving on. Going into this function, we should | |
352 | * not have processes doing IO to this device. | |
353 | */ | |
354 | blk_sync_queue(q); | |
355 | ||
31373d09 | 356 | del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer); |
483f4afc | 357 | mutex_lock(&q->sysfs_lock); |
75ad23bc | 358 | queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q); |
483f4afc AV |
359 | mutex_unlock(&q->sysfs_lock); |
360 | ||
361 | if (q->elevator) | |
362 | elevator_exit(q->elevator); | |
363 | ||
da527770 VG |
364 | blk_throtl_exit(q); |
365 | ||
483f4afc AV |
366 | blk_put_queue(q); |
367 | } | |
1da177e4 LT |
368 | EXPORT_SYMBOL(blk_cleanup_queue); |
369 | ||
165125e1 | 370 | static int blk_init_free_list(struct request_queue *q) |
1da177e4 LT |
371 | { |
372 | struct request_list *rl = &q->rq; | |
373 | ||
1abec4fd MS |
374 | if (unlikely(rl->rq_pool)) |
375 | return 0; | |
376 | ||
1faa16d2 JA |
377 | rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; |
378 | rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; | |
cb98fc8b | 379 | rl->elvpriv = 0; |
1faa16d2 JA |
380 | init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); |
381 | init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); | |
1da177e4 | 382 | |
1946089a CL |
383 | rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
384 | mempool_free_slab, request_cachep, q->node); | |
1da177e4 LT |
385 | |
386 | if (!rl->rq_pool) | |
387 | return -ENOMEM; | |
388 | ||
389 | return 0; | |
390 | } | |
391 | ||
165125e1 | 392 | struct request_queue *blk_alloc_queue(gfp_t gfp_mask) |
1da177e4 | 393 | { |
1946089a CL |
394 | return blk_alloc_queue_node(gfp_mask, -1); |
395 | } | |
396 | EXPORT_SYMBOL(blk_alloc_queue); | |
1da177e4 | 397 | |
165125e1 | 398 | struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) |
1946089a | 399 | { |
165125e1 | 400 | struct request_queue *q; |
e0bf68dd | 401 | int err; |
1946089a | 402 | |
8324aa91 | 403 | q = kmem_cache_alloc_node(blk_requestq_cachep, |
94f6030c | 404 | gfp_mask | __GFP_ZERO, node_id); |
1da177e4 LT |
405 | if (!q) |
406 | return NULL; | |
407 | ||
0989a025 JA |
408 | q->backing_dev_info.ra_pages = |
409 | (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; | |
410 | q->backing_dev_info.state = 0; | |
411 | q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; | |
d993831f | 412 | q->backing_dev_info.name = "block"; |
0989a025 | 413 | |
e0bf68dd PZ |
414 | err = bdi_init(&q->backing_dev_info); |
415 | if (err) { | |
8324aa91 | 416 | kmem_cache_free(blk_requestq_cachep, q); |
e0bf68dd PZ |
417 | return NULL; |
418 | } | |
419 | ||
e43473b7 VG |
420 | if (blk_throtl_init(q)) { |
421 | kmem_cache_free(blk_requestq_cachep, q); | |
422 | return NULL; | |
423 | } | |
424 | ||
31373d09 MG |
425 | setup_timer(&q->backing_dev_info.laptop_mode_wb_timer, |
426 | laptop_mode_timer_fn, (unsigned long) q); | |
242f9dcb JA |
427 | setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); |
428 | INIT_LIST_HEAD(&q->timeout_list); | |
ae1b1539 TH |
429 | INIT_LIST_HEAD(&q->flush_queue[0]); |
430 | INIT_LIST_HEAD(&q->flush_queue[1]); | |
431 | INIT_LIST_HEAD(&q->flush_data_in_flight); | |
3cca6dc1 | 432 | INIT_DELAYED_WORK(&q->delay_work, blk_delay_work); |
483f4afc | 433 | |
8324aa91 | 434 | kobject_init(&q->kobj, &blk_queue_ktype); |
1da177e4 | 435 | |
483f4afc | 436 | mutex_init(&q->sysfs_lock); |
e7e72bf6 | 437 | spin_lock_init(&q->__queue_lock); |
483f4afc | 438 | |
c94a96ac VG |
439 | /* |
440 | * By default initialize queue_lock to internal lock and driver can | |
441 | * override it later if need be. | |
442 | */ | |
443 | q->queue_lock = &q->__queue_lock; | |
444 | ||
1da177e4 LT |
445 | return q; |
446 | } | |
1946089a | 447 | EXPORT_SYMBOL(blk_alloc_queue_node); |
1da177e4 LT |
448 | |
449 | /** | |
450 | * blk_init_queue - prepare a request queue for use with a block device | |
451 | * @rfn: The function to be called to process requests that have been | |
452 | * placed on the queue. | |
453 | * @lock: Request queue spin lock | |
454 | * | |
455 | * Description: | |
456 | * If a block device wishes to use the standard request handling procedures, | |
457 | * which sorts requests and coalesces adjacent requests, then it must | |
458 | * call blk_init_queue(). The function @rfn will be called when there | |
459 | * are requests on the queue that need to be processed. If the device | |
460 | * supports plugging, then @rfn may not be called immediately when requests | |
461 | * are available on the queue, but may be called at some time later instead. | |
462 | * Plugged queues are generally unplugged when a buffer belonging to one | |
463 | * of the requests on the queue is needed, or due to memory pressure. | |
464 | * | |
465 | * @rfn is not required, or even expected, to remove all requests off the | |
466 | * queue, but only as many as it can handle at a time. If it does leave | |
467 | * requests on the queue, it is responsible for arranging that the requests | |
468 | * get dealt with eventually. | |
469 | * | |
470 | * The queue spin lock must be held while manipulating the requests on the | |
a038e253 PBG |
471 | * request queue; this lock will be taken also from interrupt context, so irq |
472 | * disabling is needed for it. | |
1da177e4 | 473 | * |
710027a4 | 474 | * Function returns a pointer to the initialized request queue, or %NULL if |
1da177e4 LT |
475 | * it didn't succeed. |
476 | * | |
477 | * Note: | |
478 | * blk_init_queue() must be paired with a blk_cleanup_queue() call | |
479 | * when the block device is deactivated (such as at module unload). | |
480 | **/ | |
1946089a | 481 | |
165125e1 | 482 | struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) |
1da177e4 | 483 | { |
1946089a CL |
484 | return blk_init_queue_node(rfn, lock, -1); |
485 | } | |
486 | EXPORT_SYMBOL(blk_init_queue); | |
487 | ||
165125e1 | 488 | struct request_queue * |
1946089a CL |
489 | blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) |
490 | { | |
c86d1b8a | 491 | struct request_queue *uninit_q, *q; |
1da177e4 | 492 | |
c86d1b8a MS |
493 | uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id); |
494 | if (!uninit_q) | |
495 | return NULL; | |
496 | ||
497 | q = blk_init_allocated_queue_node(uninit_q, rfn, lock, node_id); | |
498 | if (!q) | |
499 | blk_cleanup_queue(uninit_q); | |
500 | ||
501 | return q; | |
01effb0d MS |
502 | } |
503 | EXPORT_SYMBOL(blk_init_queue_node); | |
504 | ||
505 | struct request_queue * | |
506 | blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, | |
507 | spinlock_t *lock) | |
508 | { | |
509 | return blk_init_allocated_queue_node(q, rfn, lock, -1); | |
510 | } | |
511 | EXPORT_SYMBOL(blk_init_allocated_queue); | |
512 | ||
513 | struct request_queue * | |
514 | blk_init_allocated_queue_node(struct request_queue *q, request_fn_proc *rfn, | |
515 | spinlock_t *lock, int node_id) | |
516 | { | |
1da177e4 LT |
517 | if (!q) |
518 | return NULL; | |
519 | ||
1946089a | 520 | q->node = node_id; |
c86d1b8a | 521 | if (blk_init_free_list(q)) |
8669aafd | 522 | return NULL; |
1da177e4 LT |
523 | |
524 | q->request_fn = rfn; | |
1da177e4 | 525 | q->prep_rq_fn = NULL; |
28018c24 | 526 | q->unprep_rq_fn = NULL; |
bc58ba94 | 527 | q->queue_flags = QUEUE_FLAG_DEFAULT; |
c94a96ac VG |
528 | |
529 | /* Override internal queue lock with supplied lock pointer */ | |
530 | if (lock) | |
531 | q->queue_lock = lock; | |
1da177e4 | 532 | |
f3b144aa JA |
533 | /* |
534 | * This also sets hw/phys segments, boundary and size | |
535 | */ | |
1da177e4 | 536 | blk_queue_make_request(q, __make_request); |
1da177e4 | 537 | |
44ec9542 AS |
538 | q->sg_reserved_size = INT_MAX; |
539 | ||
1da177e4 LT |
540 | /* |
541 | * all done | |
542 | */ | |
543 | if (!elevator_init(q, NULL)) { | |
544 | blk_queue_congestion_threshold(q); | |
545 | return q; | |
546 | } | |
547 | ||
1da177e4 LT |
548 | return NULL; |
549 | } | |
01effb0d | 550 | EXPORT_SYMBOL(blk_init_allocated_queue_node); |
1da177e4 | 551 | |
165125e1 | 552 | int blk_get_queue(struct request_queue *q) |
1da177e4 | 553 | { |
fde6ad22 | 554 | if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { |
483f4afc | 555 | kobject_get(&q->kobj); |
1da177e4 LT |
556 | return 0; |
557 | } | |
558 | ||
559 | return 1; | |
560 | } | |
1da177e4 | 561 | |
165125e1 | 562 | static inline void blk_free_request(struct request_queue *q, struct request *rq) |
1da177e4 | 563 | { |
73c10101 JA |
564 | BUG_ON(rq->cmd_flags & REQ_ON_PLUG); |
565 | ||
4aff5e23 | 566 | if (rq->cmd_flags & REQ_ELVPRIV) |
cb98fc8b | 567 | elv_put_request(q, rq); |
1da177e4 LT |
568 | mempool_free(rq, q->rq.rq_pool); |
569 | } | |
570 | ||
1ea25ecb | 571 | static struct request * |
42dad764 | 572 | blk_alloc_request(struct request_queue *q, int flags, int priv, gfp_t gfp_mask) |
1da177e4 LT |
573 | { |
574 | struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); | |
575 | ||
576 | if (!rq) | |
577 | return NULL; | |
578 | ||
2a4aa30c | 579 | blk_rq_init(q, rq); |
1afb20f3 | 580 | |
42dad764 | 581 | rq->cmd_flags = flags | REQ_ALLOCED; |
1da177e4 | 582 | |
cb98fc8b | 583 | if (priv) { |
cb78b285 | 584 | if (unlikely(elv_set_request(q, rq, gfp_mask))) { |
cb98fc8b TH |
585 | mempool_free(rq, q->rq.rq_pool); |
586 | return NULL; | |
587 | } | |
4aff5e23 | 588 | rq->cmd_flags |= REQ_ELVPRIV; |
cb98fc8b | 589 | } |
1da177e4 | 590 | |
cb98fc8b | 591 | return rq; |
1da177e4 LT |
592 | } |
593 | ||
594 | /* | |
595 | * ioc_batching returns true if the ioc is a valid batching request and | |
596 | * should be given priority access to a request. | |
597 | */ | |
165125e1 | 598 | static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) |
1da177e4 LT |
599 | { |
600 | if (!ioc) | |
601 | return 0; | |
602 | ||
603 | /* | |
604 | * Make sure the process is able to allocate at least 1 request | |
605 | * even if the batch times out, otherwise we could theoretically | |
606 | * lose wakeups. | |
607 | */ | |
608 | return ioc->nr_batch_requests == q->nr_batching || | |
609 | (ioc->nr_batch_requests > 0 | |
610 | && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); | |
611 | } | |
612 | ||
613 | /* | |
614 | * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This | |
615 | * will cause the process to be a "batcher" on all queues in the system. This | |
616 | * is the behaviour we want though - once it gets a wakeup it should be given | |
617 | * a nice run. | |
618 | */ | |
165125e1 | 619 | static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) |
1da177e4 LT |
620 | { |
621 | if (!ioc || ioc_batching(q, ioc)) | |
622 | return; | |
623 | ||
624 | ioc->nr_batch_requests = q->nr_batching; | |
625 | ioc->last_waited = jiffies; | |
626 | } | |
627 | ||
1faa16d2 | 628 | static void __freed_request(struct request_queue *q, int sync) |
1da177e4 LT |
629 | { |
630 | struct request_list *rl = &q->rq; | |
631 | ||
1faa16d2 JA |
632 | if (rl->count[sync] < queue_congestion_off_threshold(q)) |
633 | blk_clear_queue_congested(q, sync); | |
1da177e4 | 634 | |
1faa16d2 JA |
635 | if (rl->count[sync] + 1 <= q->nr_requests) { |
636 | if (waitqueue_active(&rl->wait[sync])) | |
637 | wake_up(&rl->wait[sync]); | |
1da177e4 | 638 | |
1faa16d2 | 639 | blk_clear_queue_full(q, sync); |
1da177e4 LT |
640 | } |
641 | } | |
642 | ||
643 | /* | |
644 | * A request has just been released. Account for it, update the full and | |
645 | * congestion status, wake up any waiters. Called under q->queue_lock. | |
646 | */ | |
1faa16d2 | 647 | static void freed_request(struct request_queue *q, int sync, int priv) |
1da177e4 LT |
648 | { |
649 | struct request_list *rl = &q->rq; | |
650 | ||
1faa16d2 | 651 | rl->count[sync]--; |
cb98fc8b TH |
652 | if (priv) |
653 | rl->elvpriv--; | |
1da177e4 | 654 | |
1faa16d2 | 655 | __freed_request(q, sync); |
1da177e4 | 656 | |
1faa16d2 JA |
657 | if (unlikely(rl->starved[sync ^ 1])) |
658 | __freed_request(q, sync ^ 1); | |
1da177e4 LT |
659 | } |
660 | ||
9d5a4e94 MS |
661 | /* |
662 | * Determine if elevator data should be initialized when allocating the | |
663 | * request associated with @bio. | |
664 | */ | |
665 | static bool blk_rq_should_init_elevator(struct bio *bio) | |
666 | { | |
667 | if (!bio) | |
668 | return true; | |
669 | ||
670 | /* | |
671 | * Flush requests do not use the elevator so skip initialization. | |
672 | * This allows a request to share the flush and elevator data. | |
673 | */ | |
674 | if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) | |
675 | return false; | |
676 | ||
677 | return true; | |
678 | } | |
679 | ||
1da177e4 | 680 | /* |
d6344532 NP |
681 | * Get a free request, queue_lock must be held. |
682 | * Returns NULL on failure, with queue_lock held. | |
683 | * Returns !NULL on success, with queue_lock *not held*. | |
1da177e4 | 684 | */ |
165125e1 | 685 | static struct request *get_request(struct request_queue *q, int rw_flags, |
7749a8d4 | 686 | struct bio *bio, gfp_t gfp_mask) |
1da177e4 LT |
687 | { |
688 | struct request *rq = NULL; | |
689 | struct request_list *rl = &q->rq; | |
88ee5ef1 | 690 | struct io_context *ioc = NULL; |
1faa16d2 | 691 | const bool is_sync = rw_is_sync(rw_flags) != 0; |
9d5a4e94 | 692 | int may_queue, priv = 0; |
88ee5ef1 | 693 | |
7749a8d4 | 694 | may_queue = elv_may_queue(q, rw_flags); |
88ee5ef1 JA |
695 | if (may_queue == ELV_MQUEUE_NO) |
696 | goto rq_starved; | |
697 | ||
1faa16d2 JA |
698 | if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { |
699 | if (rl->count[is_sync]+1 >= q->nr_requests) { | |
b5deef90 | 700 | ioc = current_io_context(GFP_ATOMIC, q->node); |
88ee5ef1 JA |
701 | /* |
702 | * The queue will fill after this allocation, so set | |
703 | * it as full, and mark this process as "batching". | |
704 | * This process will be allowed to complete a batch of | |
705 | * requests, others will be blocked. | |
706 | */ | |
1faa16d2 | 707 | if (!blk_queue_full(q, is_sync)) { |
88ee5ef1 | 708 | ioc_set_batching(q, ioc); |
1faa16d2 | 709 | blk_set_queue_full(q, is_sync); |
88ee5ef1 JA |
710 | } else { |
711 | if (may_queue != ELV_MQUEUE_MUST | |
712 | && !ioc_batching(q, ioc)) { | |
713 | /* | |
714 | * The queue is full and the allocating | |
715 | * process is not a "batcher", and not | |
716 | * exempted by the IO scheduler | |
717 | */ | |
718 | goto out; | |
719 | } | |
720 | } | |
1da177e4 | 721 | } |
1faa16d2 | 722 | blk_set_queue_congested(q, is_sync); |
1da177e4 LT |
723 | } |
724 | ||
082cf69e JA |
725 | /* |
726 | * Only allow batching queuers to allocate up to 50% over the defined | |
727 | * limit of requests, otherwise we could have thousands of requests | |
728 | * allocated with any setting of ->nr_requests | |
729 | */ | |
1faa16d2 | 730 | if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) |
082cf69e | 731 | goto out; |
fd782a4a | 732 | |
1faa16d2 JA |
733 | rl->count[is_sync]++; |
734 | rl->starved[is_sync] = 0; | |
cb98fc8b | 735 | |
9d5a4e94 MS |
736 | if (blk_rq_should_init_elevator(bio)) { |
737 | priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); | |
738 | if (priv) | |
739 | rl->elvpriv++; | |
740 | } | |
cb98fc8b | 741 | |
f253b86b JA |
742 | if (blk_queue_io_stat(q)) |
743 | rw_flags |= REQ_IO_STAT; | |
1da177e4 LT |
744 | spin_unlock_irq(q->queue_lock); |
745 | ||
7749a8d4 | 746 | rq = blk_alloc_request(q, rw_flags, priv, gfp_mask); |
88ee5ef1 | 747 | if (unlikely(!rq)) { |
1da177e4 LT |
748 | /* |
749 | * Allocation failed presumably due to memory. Undo anything | |
750 | * we might have messed up. | |
751 | * | |
752 | * Allocating task should really be put onto the front of the | |
753 | * wait queue, but this is pretty rare. | |
754 | */ | |
755 | spin_lock_irq(q->queue_lock); | |
1faa16d2 | 756 | freed_request(q, is_sync, priv); |
1da177e4 LT |
757 | |
758 | /* | |
759 | * in the very unlikely event that allocation failed and no | |
760 | * requests for this direction was pending, mark us starved | |
761 | * so that freeing of a request in the other direction will | |
762 | * notice us. another possible fix would be to split the | |
763 | * rq mempool into READ and WRITE | |
764 | */ | |
765 | rq_starved: | |
1faa16d2 JA |
766 | if (unlikely(rl->count[is_sync] == 0)) |
767 | rl->starved[is_sync] = 1; | |
1da177e4 | 768 | |
1da177e4 LT |
769 | goto out; |
770 | } | |
771 | ||
88ee5ef1 JA |
772 | /* |
773 | * ioc may be NULL here, and ioc_batching will be false. That's | |
774 | * OK, if the queue is under the request limit then requests need | |
775 | * not count toward the nr_batch_requests limit. There will always | |
776 | * be some limit enforced by BLK_BATCH_TIME. | |
777 | */ | |
1da177e4 LT |
778 | if (ioc_batching(q, ioc)) |
779 | ioc->nr_batch_requests--; | |
6728cb0e | 780 | |
1faa16d2 | 781 | trace_block_getrq(q, bio, rw_flags & 1); |
1da177e4 | 782 | out: |
1da177e4 LT |
783 | return rq; |
784 | } | |
785 | ||
786 | /* | |
7eaceacc JA |
787 | * No available requests for this queue, wait for some requests to become |
788 | * available. | |
d6344532 NP |
789 | * |
790 | * Called with q->queue_lock held, and returns with it unlocked. | |
1da177e4 | 791 | */ |
165125e1 | 792 | static struct request *get_request_wait(struct request_queue *q, int rw_flags, |
22e2c507 | 793 | struct bio *bio) |
1da177e4 | 794 | { |
1faa16d2 | 795 | const bool is_sync = rw_is_sync(rw_flags) != 0; |
1da177e4 LT |
796 | struct request *rq; |
797 | ||
7749a8d4 | 798 | rq = get_request(q, rw_flags, bio, GFP_NOIO); |
450991bc NP |
799 | while (!rq) { |
800 | DEFINE_WAIT(wait); | |
05caf8db | 801 | struct io_context *ioc; |
1da177e4 LT |
802 | struct request_list *rl = &q->rq; |
803 | ||
1faa16d2 | 804 | prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, |
1da177e4 LT |
805 | TASK_UNINTERRUPTIBLE); |
806 | ||
1faa16d2 | 807 | trace_block_sleeprq(q, bio, rw_flags & 1); |
1da177e4 | 808 | |
05caf8db ZY |
809 | spin_unlock_irq(q->queue_lock); |
810 | io_schedule(); | |
1da177e4 | 811 | |
05caf8db ZY |
812 | /* |
813 | * After sleeping, we become a "batching" process and | |
814 | * will be able to allocate at least one request, and | |
815 | * up to a big batch of them for a small period time. | |
816 | * See ioc_batching, ioc_set_batching | |
817 | */ | |
818 | ioc = current_io_context(GFP_NOIO, q->node); | |
819 | ioc_set_batching(q, ioc); | |
d6344532 | 820 | |
05caf8db | 821 | spin_lock_irq(q->queue_lock); |
1faa16d2 | 822 | finish_wait(&rl->wait[is_sync], &wait); |
05caf8db ZY |
823 | |
824 | rq = get_request(q, rw_flags, bio, GFP_NOIO); | |
825 | }; | |
1da177e4 LT |
826 | |
827 | return rq; | |
828 | } | |
829 | ||
165125e1 | 830 | struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) |
1da177e4 LT |
831 | { |
832 | struct request *rq; | |
833 | ||
834 | BUG_ON(rw != READ && rw != WRITE); | |
835 | ||
d6344532 NP |
836 | spin_lock_irq(q->queue_lock); |
837 | if (gfp_mask & __GFP_WAIT) { | |
22e2c507 | 838 | rq = get_request_wait(q, rw, NULL); |
d6344532 | 839 | } else { |
22e2c507 | 840 | rq = get_request(q, rw, NULL, gfp_mask); |
d6344532 NP |
841 | if (!rq) |
842 | spin_unlock_irq(q->queue_lock); | |
843 | } | |
844 | /* q->queue_lock is unlocked at this point */ | |
1da177e4 LT |
845 | |
846 | return rq; | |
847 | } | |
1da177e4 LT |
848 | EXPORT_SYMBOL(blk_get_request); |
849 | ||
dc72ef4a | 850 | /** |
79eb63e9 | 851 | * blk_make_request - given a bio, allocate a corresponding struct request. |
8ebf9756 | 852 | * @q: target request queue |
79eb63e9 BH |
853 | * @bio: The bio describing the memory mappings that will be submitted for IO. |
854 | * It may be a chained-bio properly constructed by block/bio layer. | |
8ebf9756 | 855 | * @gfp_mask: gfp flags to be used for memory allocation |
dc72ef4a | 856 | * |
79eb63e9 BH |
857 | * blk_make_request is the parallel of generic_make_request for BLOCK_PC |
858 | * type commands. Where the struct request needs to be farther initialized by | |
859 | * the caller. It is passed a &struct bio, which describes the memory info of | |
860 | * the I/O transfer. | |
dc72ef4a | 861 | * |
79eb63e9 BH |
862 | * The caller of blk_make_request must make sure that bi_io_vec |
863 | * are set to describe the memory buffers. That bio_data_dir() will return | |
864 | * the needed direction of the request. (And all bio's in the passed bio-chain | |
865 | * are properly set accordingly) | |
866 | * | |
867 | * If called under none-sleepable conditions, mapped bio buffers must not | |
868 | * need bouncing, by calling the appropriate masked or flagged allocator, | |
869 | * suitable for the target device. Otherwise the call to blk_queue_bounce will | |
870 | * BUG. | |
53674ac5 JA |
871 | * |
872 | * WARNING: When allocating/cloning a bio-chain, careful consideration should be | |
873 | * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for | |
874 | * anything but the first bio in the chain. Otherwise you risk waiting for IO | |
875 | * completion of a bio that hasn't been submitted yet, thus resulting in a | |
876 | * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead | |
877 | * of bio_alloc(), as that avoids the mempool deadlock. | |
878 | * If possible a big IO should be split into smaller parts when allocation | |
879 | * fails. Partial allocation should not be an error, or you risk a live-lock. | |
dc72ef4a | 880 | */ |
79eb63e9 BH |
881 | struct request *blk_make_request(struct request_queue *q, struct bio *bio, |
882 | gfp_t gfp_mask) | |
dc72ef4a | 883 | { |
79eb63e9 BH |
884 | struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask); |
885 | ||
886 | if (unlikely(!rq)) | |
887 | return ERR_PTR(-ENOMEM); | |
888 | ||
889 | for_each_bio(bio) { | |
890 | struct bio *bounce_bio = bio; | |
891 | int ret; | |
892 | ||
893 | blk_queue_bounce(q, &bounce_bio); | |
894 | ret = blk_rq_append_bio(q, rq, bounce_bio); | |
895 | if (unlikely(ret)) { | |
896 | blk_put_request(rq); | |
897 | return ERR_PTR(ret); | |
898 | } | |
899 | } | |
900 | ||
901 | return rq; | |
dc72ef4a | 902 | } |
79eb63e9 | 903 | EXPORT_SYMBOL(blk_make_request); |
dc72ef4a | 904 | |
1da177e4 LT |
905 | /** |
906 | * blk_requeue_request - put a request back on queue | |
907 | * @q: request queue where request should be inserted | |
908 | * @rq: request to be inserted | |
909 | * | |
910 | * Description: | |
911 | * Drivers often keep queueing requests until the hardware cannot accept | |
912 | * more, when that condition happens we need to put the request back | |
913 | * on the queue. Must be called with queue lock held. | |
914 | */ | |
165125e1 | 915 | void blk_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 916 | { |
242f9dcb JA |
917 | blk_delete_timer(rq); |
918 | blk_clear_rq_complete(rq); | |
5f3ea37c | 919 | trace_block_rq_requeue(q, rq); |
2056a782 | 920 | |
1da177e4 LT |
921 | if (blk_rq_tagged(rq)) |
922 | blk_queue_end_tag(q, rq); | |
923 | ||
ba396a6c JB |
924 | BUG_ON(blk_queued_rq(rq)); |
925 | ||
1da177e4 LT |
926 | elv_requeue_request(q, rq); |
927 | } | |
1da177e4 LT |
928 | EXPORT_SYMBOL(blk_requeue_request); |
929 | ||
73c10101 JA |
930 | static void add_acct_request(struct request_queue *q, struct request *rq, |
931 | int where) | |
932 | { | |
933 | drive_stat_acct(rq, 1); | |
7eaceacc | 934 | __elv_add_request(q, rq, where); |
73c10101 JA |
935 | } |
936 | ||
1da177e4 | 937 | /** |
710027a4 | 938 | * blk_insert_request - insert a special request into a request queue |
1da177e4 LT |
939 | * @q: request queue where request should be inserted |
940 | * @rq: request to be inserted | |
941 | * @at_head: insert request at head or tail of queue | |
942 | * @data: private data | |
1da177e4 LT |
943 | * |
944 | * Description: | |
945 | * Many block devices need to execute commands asynchronously, so they don't | |
946 | * block the whole kernel from preemption during request execution. This is | |
947 | * accomplished normally by inserting aritficial requests tagged as | |
710027a4 RD |
948 | * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them |
949 | * be scheduled for actual execution by the request queue. | |
1da177e4 LT |
950 | * |
951 | * We have the option of inserting the head or the tail of the queue. | |
952 | * Typically we use the tail for new ioctls and so forth. We use the head | |
953 | * of the queue for things like a QUEUE_FULL message from a device, or a | |
954 | * host that is unable to accept a particular command. | |
955 | */ | |
165125e1 | 956 | void blk_insert_request(struct request_queue *q, struct request *rq, |
867d1191 | 957 | int at_head, void *data) |
1da177e4 | 958 | { |
867d1191 | 959 | int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; |
1da177e4 LT |
960 | unsigned long flags; |
961 | ||
962 | /* | |
963 | * tell I/O scheduler that this isn't a regular read/write (ie it | |
964 | * must not attempt merges on this) and that it acts as a soft | |
965 | * barrier | |
966 | */ | |
4aff5e23 | 967 | rq->cmd_type = REQ_TYPE_SPECIAL; |
1da177e4 LT |
968 | |
969 | rq->special = data; | |
970 | ||
971 | spin_lock_irqsave(q->queue_lock, flags); | |
972 | ||
973 | /* | |
974 | * If command is tagged, release the tag | |
975 | */ | |
867d1191 TH |
976 | if (blk_rq_tagged(rq)) |
977 | blk_queue_end_tag(q, rq); | |
1da177e4 | 978 | |
73c10101 | 979 | add_acct_request(q, rq, where); |
1654e741 | 980 | __blk_run_queue(q, false); |
1da177e4 LT |
981 | spin_unlock_irqrestore(q->queue_lock, flags); |
982 | } | |
1da177e4 LT |
983 | EXPORT_SYMBOL(blk_insert_request); |
984 | ||
074a7aca TH |
985 | static void part_round_stats_single(int cpu, struct hd_struct *part, |
986 | unsigned long now) | |
987 | { | |
988 | if (now == part->stamp) | |
989 | return; | |
990 | ||
316d315b | 991 | if (part_in_flight(part)) { |
074a7aca | 992 | __part_stat_add(cpu, part, time_in_queue, |
316d315b | 993 | part_in_flight(part) * (now - part->stamp)); |
074a7aca TH |
994 | __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); |
995 | } | |
996 | part->stamp = now; | |
997 | } | |
998 | ||
999 | /** | |
496aa8a9 RD |
1000 | * part_round_stats() - Round off the performance stats on a struct disk_stats. |
1001 | * @cpu: cpu number for stats access | |
1002 | * @part: target partition | |
1da177e4 LT |
1003 | * |
1004 | * The average IO queue length and utilisation statistics are maintained | |
1005 | * by observing the current state of the queue length and the amount of | |
1006 | * time it has been in this state for. | |
1007 | * | |
1008 | * Normally, that accounting is done on IO completion, but that can result | |
1009 | * in more than a second's worth of IO being accounted for within any one | |
1010 | * second, leading to >100% utilisation. To deal with that, we call this | |
1011 | * function to do a round-off before returning the results when reading | |
1012 | * /proc/diskstats. This accounts immediately for all queue usage up to | |
1013 | * the current jiffies and restarts the counters again. | |
1014 | */ | |
c9959059 | 1015 | void part_round_stats(int cpu, struct hd_struct *part) |
6f2576af JM |
1016 | { |
1017 | unsigned long now = jiffies; | |
1018 | ||
074a7aca TH |
1019 | if (part->partno) |
1020 | part_round_stats_single(cpu, &part_to_disk(part)->part0, now); | |
1021 | part_round_stats_single(cpu, part, now); | |
6f2576af | 1022 | } |
074a7aca | 1023 | EXPORT_SYMBOL_GPL(part_round_stats); |
6f2576af | 1024 | |
1da177e4 LT |
1025 | /* |
1026 | * queue lock must be held | |
1027 | */ | |
165125e1 | 1028 | void __blk_put_request(struct request_queue *q, struct request *req) |
1da177e4 | 1029 | { |
1da177e4 LT |
1030 | if (unlikely(!q)) |
1031 | return; | |
1032 | if (unlikely(--req->ref_count)) | |
1033 | return; | |
1034 | ||
8922e16c TH |
1035 | elv_completed_request(q, req); |
1036 | ||
1cd96c24 BH |
1037 | /* this is a bio leak */ |
1038 | WARN_ON(req->bio != NULL); | |
1039 | ||
1da177e4 LT |
1040 | /* |
1041 | * Request may not have originated from ll_rw_blk. if not, | |
1042 | * it didn't come out of our reserved rq pools | |
1043 | */ | |
49171e5c | 1044 | if (req->cmd_flags & REQ_ALLOCED) { |
1faa16d2 | 1045 | int is_sync = rq_is_sync(req) != 0; |
4aff5e23 | 1046 | int priv = req->cmd_flags & REQ_ELVPRIV; |
1da177e4 | 1047 | |
1da177e4 | 1048 | BUG_ON(!list_empty(&req->queuelist)); |
9817064b | 1049 | BUG_ON(!hlist_unhashed(&req->hash)); |
1da177e4 LT |
1050 | |
1051 | blk_free_request(q, req); | |
1faa16d2 | 1052 | freed_request(q, is_sync, priv); |
1da177e4 LT |
1053 | } |
1054 | } | |
6e39b69e MC |
1055 | EXPORT_SYMBOL_GPL(__blk_put_request); |
1056 | ||
1da177e4 LT |
1057 | void blk_put_request(struct request *req) |
1058 | { | |
8922e16c | 1059 | unsigned long flags; |
165125e1 | 1060 | struct request_queue *q = req->q; |
8922e16c | 1061 | |
52a93ba8 FT |
1062 | spin_lock_irqsave(q->queue_lock, flags); |
1063 | __blk_put_request(q, req); | |
1064 | spin_unlock_irqrestore(q->queue_lock, flags); | |
1da177e4 | 1065 | } |
1da177e4 LT |
1066 | EXPORT_SYMBOL(blk_put_request); |
1067 | ||
66ac0280 CH |
1068 | /** |
1069 | * blk_add_request_payload - add a payload to a request | |
1070 | * @rq: request to update | |
1071 | * @page: page backing the payload | |
1072 | * @len: length of the payload. | |
1073 | * | |
1074 | * This allows to later add a payload to an already submitted request by | |
1075 | * a block driver. The driver needs to take care of freeing the payload | |
1076 | * itself. | |
1077 | * | |
1078 | * Note that this is a quite horrible hack and nothing but handling of | |
1079 | * discard requests should ever use it. | |
1080 | */ | |
1081 | void blk_add_request_payload(struct request *rq, struct page *page, | |
1082 | unsigned int len) | |
1083 | { | |
1084 | struct bio *bio = rq->bio; | |
1085 | ||
1086 | bio->bi_io_vec->bv_page = page; | |
1087 | bio->bi_io_vec->bv_offset = 0; | |
1088 | bio->bi_io_vec->bv_len = len; | |
1089 | ||
1090 | bio->bi_size = len; | |
1091 | bio->bi_vcnt = 1; | |
1092 | bio->bi_phys_segments = 1; | |
1093 | ||
1094 | rq->__data_len = rq->resid_len = len; | |
1095 | rq->nr_phys_segments = 1; | |
1096 | rq->buffer = bio_data(bio); | |
1097 | } | |
1098 | EXPORT_SYMBOL_GPL(blk_add_request_payload); | |
1099 | ||
73c10101 JA |
1100 | static bool bio_attempt_back_merge(struct request_queue *q, struct request *req, |
1101 | struct bio *bio) | |
1102 | { | |
1103 | const int ff = bio->bi_rw & REQ_FAILFAST_MASK; | |
1104 | ||
1105 | /* | |
1106 | * Debug stuff, kill later | |
1107 | */ | |
1108 | if (!rq_mergeable(req)) { | |
1109 | blk_dump_rq_flags(req, "back"); | |
1110 | return false; | |
1111 | } | |
1112 | ||
1113 | if (!ll_back_merge_fn(q, req, bio)) | |
1114 | return false; | |
1115 | ||
1116 | trace_block_bio_backmerge(q, bio); | |
1117 | ||
1118 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) | |
1119 | blk_rq_set_mixed_merge(req); | |
1120 | ||
1121 | req->biotail->bi_next = bio; | |
1122 | req->biotail = bio; | |
1123 | req->__data_len += bio->bi_size; | |
1124 | req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); | |
1125 | ||
1126 | drive_stat_acct(req, 0); | |
1127 | return true; | |
1128 | } | |
1129 | ||
1130 | static bool bio_attempt_front_merge(struct request_queue *q, | |
1131 | struct request *req, struct bio *bio) | |
1132 | { | |
1133 | const int ff = bio->bi_rw & REQ_FAILFAST_MASK; | |
1134 | sector_t sector; | |
1135 | ||
1136 | /* | |
1137 | * Debug stuff, kill later | |
1138 | */ | |
1139 | if (!rq_mergeable(req)) { | |
1140 | blk_dump_rq_flags(req, "front"); | |
1141 | return false; | |
1142 | } | |
1143 | ||
1144 | if (!ll_front_merge_fn(q, req, bio)) | |
1145 | return false; | |
1146 | ||
1147 | trace_block_bio_frontmerge(q, bio); | |
1148 | ||
1149 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) | |
1150 | blk_rq_set_mixed_merge(req); | |
1151 | ||
1152 | sector = bio->bi_sector; | |
1153 | ||
1154 | bio->bi_next = req->bio; | |
1155 | req->bio = bio; | |
1156 | ||
1157 | /* | |
1158 | * may not be valid. if the low level driver said | |
1159 | * it didn't need a bounce buffer then it better | |
1160 | * not touch req->buffer either... | |
1161 | */ | |
1162 | req->buffer = bio_data(bio); | |
1163 | req->__sector = bio->bi_sector; | |
1164 | req->__data_len += bio->bi_size; | |
1165 | req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); | |
1166 | ||
1167 | drive_stat_acct(req, 0); | |
1168 | return true; | |
1169 | } | |
1170 | ||
1171 | /* | |
1172 | * Attempts to merge with the plugged list in the current process. Returns | |
25985edc | 1173 | * true if merge was successful, otherwise false. |
73c10101 JA |
1174 | */ |
1175 | static bool attempt_plug_merge(struct task_struct *tsk, struct request_queue *q, | |
1176 | struct bio *bio) | |
1177 | { | |
1178 | struct blk_plug *plug; | |
1179 | struct request *rq; | |
1180 | bool ret = false; | |
1181 | ||
1182 | plug = tsk->plug; | |
1183 | if (!plug) | |
1184 | goto out; | |
1185 | ||
1186 | list_for_each_entry_reverse(rq, &plug->list, queuelist) { | |
1187 | int el_ret; | |
1188 | ||
1189 | if (rq->q != q) | |
1190 | continue; | |
1191 | ||
1192 | el_ret = elv_try_merge(rq, bio); | |
1193 | if (el_ret == ELEVATOR_BACK_MERGE) { | |
1194 | ret = bio_attempt_back_merge(q, rq, bio); | |
1195 | if (ret) | |
1196 | break; | |
1197 | } else if (el_ret == ELEVATOR_FRONT_MERGE) { | |
1198 | ret = bio_attempt_front_merge(q, rq, bio); | |
1199 | if (ret) | |
1200 | break; | |
1201 | } | |
1202 | } | |
1203 | out: | |
1204 | return ret; | |
1205 | } | |
1206 | ||
86db1e29 | 1207 | void init_request_from_bio(struct request *req, struct bio *bio) |
52d9e675 | 1208 | { |
c7c22e4d | 1209 | req->cpu = bio->bi_comp_cpu; |
4aff5e23 | 1210 | req->cmd_type = REQ_TYPE_FS; |
52d9e675 | 1211 | |
7b6d91da CH |
1212 | req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK; |
1213 | if (bio->bi_rw & REQ_RAHEAD) | |
a82afdfc | 1214 | req->cmd_flags |= REQ_FAILFAST_MASK; |
b31dc66a | 1215 | |
52d9e675 | 1216 | req->errors = 0; |
a2dec7b3 | 1217 | req->__sector = bio->bi_sector; |
52d9e675 | 1218 | req->ioprio = bio_prio(bio); |
bc1c56fd | 1219 | blk_rq_bio_prep(req->q, req, bio); |
52d9e675 TH |
1220 | } |
1221 | ||
165125e1 | 1222 | static int __make_request(struct request_queue *q, struct bio *bio) |
1da177e4 | 1223 | { |
5e00d1b5 | 1224 | const bool sync = !!(bio->bi_rw & REQ_SYNC); |
73c10101 JA |
1225 | struct blk_plug *plug; |
1226 | int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT; | |
1227 | struct request *req; | |
1da177e4 | 1228 | |
1da177e4 LT |
1229 | /* |
1230 | * low level driver can indicate that it wants pages above a | |
1231 | * certain limit bounced to low memory (ie for highmem, or even | |
1232 | * ISA dma in theory) | |
1233 | */ | |
1234 | blk_queue_bounce(q, &bio); | |
1235 | ||
4fed947c | 1236 | if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { |
73c10101 | 1237 | spin_lock_irq(q->queue_lock); |
ae1b1539 | 1238 | where = ELEVATOR_INSERT_FLUSH; |
28e7d184 TH |
1239 | goto get_rq; |
1240 | } | |
1241 | ||
73c10101 JA |
1242 | /* |
1243 | * Check if we can merge with the plugged list before grabbing | |
1244 | * any locks. | |
1245 | */ | |
1246 | if (attempt_plug_merge(current, q, bio)) | |
6728cb0e | 1247 | goto out; |
1da177e4 | 1248 | |
73c10101 | 1249 | spin_lock_irq(q->queue_lock); |
2056a782 | 1250 | |
73c10101 JA |
1251 | el_ret = elv_merge(q, &req, bio); |
1252 | if (el_ret == ELEVATOR_BACK_MERGE) { | |
1253 | BUG_ON(req->cmd_flags & REQ_ON_PLUG); | |
1254 | if (bio_attempt_back_merge(q, req, bio)) { | |
1255 | if (!attempt_back_merge(q, req)) | |
1256 | elv_merged_request(q, req, el_ret); | |
1257 | goto out_unlock; | |
1258 | } | |
1259 | } else if (el_ret == ELEVATOR_FRONT_MERGE) { | |
1260 | BUG_ON(req->cmd_flags & REQ_ON_PLUG); | |
1261 | if (bio_attempt_front_merge(q, req, bio)) { | |
1262 | if (!attempt_front_merge(q, req)) | |
1263 | elv_merged_request(q, req, el_ret); | |
1264 | goto out_unlock; | |
80a761fd | 1265 | } |
1da177e4 LT |
1266 | } |
1267 | ||
450991bc | 1268 | get_rq: |
7749a8d4 JA |
1269 | /* |
1270 | * This sync check and mask will be re-done in init_request_from_bio(), | |
1271 | * but we need to set it earlier to expose the sync flag to the | |
1272 | * rq allocator and io schedulers. | |
1273 | */ | |
1274 | rw_flags = bio_data_dir(bio); | |
1275 | if (sync) | |
7b6d91da | 1276 | rw_flags |= REQ_SYNC; |
7749a8d4 | 1277 | |
1da177e4 | 1278 | /* |
450991bc | 1279 | * Grab a free request. This is might sleep but can not fail. |
d6344532 | 1280 | * Returns with the queue unlocked. |
450991bc | 1281 | */ |
7749a8d4 | 1282 | req = get_request_wait(q, rw_flags, bio); |
d6344532 | 1283 | |
450991bc NP |
1284 | /* |
1285 | * After dropping the lock and possibly sleeping here, our request | |
1286 | * may now be mergeable after it had proven unmergeable (above). | |
1287 | * We don't worry about that case for efficiency. It won't happen | |
1288 | * often, and the elevators are able to handle it. | |
1da177e4 | 1289 | */ |
52d9e675 | 1290 | init_request_from_bio(req, bio); |
1da177e4 | 1291 | |
c7c22e4d | 1292 | if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) || |
73c10101 JA |
1293 | bio_flagged(bio, BIO_CPU_AFFINE)) { |
1294 | req->cpu = blk_cpu_to_group(get_cpu()); | |
1295 | put_cpu(); | |
1296 | } | |
1297 | ||
1298 | plug = current->plug; | |
721a9602 | 1299 | if (plug) { |
dc6d36c9 JA |
1300 | /* |
1301 | * If this is the first request added after a plug, fire | |
1302 | * of a plug trace. If others have been added before, check | |
1303 | * if we have multiple devices in this plug. If so, make a | |
1304 | * note to sort the list before dispatch. | |
1305 | */ | |
1306 | if (list_empty(&plug->list)) | |
1307 | trace_block_plug(q); | |
1308 | else if (!plug->should_sort) { | |
73c10101 JA |
1309 | struct request *__rq; |
1310 | ||
1311 | __rq = list_entry_rq(plug->list.prev); | |
1312 | if (__rq->q != q) | |
1313 | plug->should_sort = 1; | |
1314 | } | |
1315 | /* | |
1316 | * Debug flag, kill later | |
1317 | */ | |
1318 | req->cmd_flags |= REQ_ON_PLUG; | |
1319 | list_add_tail(&req->queuelist, &plug->list); | |
1320 | drive_stat_acct(req, 1); | |
1321 | } else { | |
1322 | spin_lock_irq(q->queue_lock); | |
1323 | add_acct_request(q, req, where); | |
4c63f564 | 1324 | __blk_run_queue(q, false); |
73c10101 JA |
1325 | out_unlock: |
1326 | spin_unlock_irq(q->queue_lock); | |
1327 | } | |
1da177e4 | 1328 | out: |
1da177e4 | 1329 | return 0; |
1da177e4 LT |
1330 | } |
1331 | ||
1332 | /* | |
1333 | * If bio->bi_dev is a partition, remap the location | |
1334 | */ | |
1335 | static inline void blk_partition_remap(struct bio *bio) | |
1336 | { | |
1337 | struct block_device *bdev = bio->bi_bdev; | |
1338 | ||
bf2de6f5 | 1339 | if (bio_sectors(bio) && bdev != bdev->bd_contains) { |
1da177e4 LT |
1340 | struct hd_struct *p = bdev->bd_part; |
1341 | ||
1da177e4 LT |
1342 | bio->bi_sector += p->start_sect; |
1343 | bio->bi_bdev = bdev->bd_contains; | |
c7149d6b | 1344 | |
d07335e5 MS |
1345 | trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio, |
1346 | bdev->bd_dev, | |
1347 | bio->bi_sector - p->start_sect); | |
1da177e4 LT |
1348 | } |
1349 | } | |
1350 | ||
1da177e4 LT |
1351 | static void handle_bad_sector(struct bio *bio) |
1352 | { | |
1353 | char b[BDEVNAME_SIZE]; | |
1354 | ||
1355 | printk(KERN_INFO "attempt to access beyond end of device\n"); | |
1356 | printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", | |
1357 | bdevname(bio->bi_bdev, b), | |
1358 | bio->bi_rw, | |
1359 | (unsigned long long)bio->bi_sector + bio_sectors(bio), | |
77304d2a | 1360 | (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9)); |
1da177e4 LT |
1361 | |
1362 | set_bit(BIO_EOF, &bio->bi_flags); | |
1363 | } | |
1364 | ||
c17bb495 AM |
1365 | #ifdef CONFIG_FAIL_MAKE_REQUEST |
1366 | ||
1367 | static DECLARE_FAULT_ATTR(fail_make_request); | |
1368 | ||
1369 | static int __init setup_fail_make_request(char *str) | |
1370 | { | |
1371 | return setup_fault_attr(&fail_make_request, str); | |
1372 | } | |
1373 | __setup("fail_make_request=", setup_fail_make_request); | |
1374 | ||
1375 | static int should_fail_request(struct bio *bio) | |
1376 | { | |
eddb2e26 TH |
1377 | struct hd_struct *part = bio->bi_bdev->bd_part; |
1378 | ||
1379 | if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail) | |
c17bb495 AM |
1380 | return should_fail(&fail_make_request, bio->bi_size); |
1381 | ||
1382 | return 0; | |
1383 | } | |
1384 | ||
1385 | static int __init fail_make_request_debugfs(void) | |
1386 | { | |
1387 | return init_fault_attr_dentries(&fail_make_request, | |
1388 | "fail_make_request"); | |
1389 | } | |
1390 | ||
1391 | late_initcall(fail_make_request_debugfs); | |
1392 | ||
1393 | #else /* CONFIG_FAIL_MAKE_REQUEST */ | |
1394 | ||
1395 | static inline int should_fail_request(struct bio *bio) | |
1396 | { | |
1397 | return 0; | |
1398 | } | |
1399 | ||
1400 | #endif /* CONFIG_FAIL_MAKE_REQUEST */ | |
1401 | ||
c07e2b41 JA |
1402 | /* |
1403 | * Check whether this bio extends beyond the end of the device. | |
1404 | */ | |
1405 | static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) | |
1406 | { | |
1407 | sector_t maxsector; | |
1408 | ||
1409 | if (!nr_sectors) | |
1410 | return 0; | |
1411 | ||
1412 | /* Test device or partition size, when known. */ | |
77304d2a | 1413 | maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; |
c07e2b41 JA |
1414 | if (maxsector) { |
1415 | sector_t sector = bio->bi_sector; | |
1416 | ||
1417 | if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { | |
1418 | /* | |
1419 | * This may well happen - the kernel calls bread() | |
1420 | * without checking the size of the device, e.g., when | |
1421 | * mounting a device. | |
1422 | */ | |
1423 | handle_bad_sector(bio); | |
1424 | return 1; | |
1425 | } | |
1426 | } | |
1427 | ||
1428 | return 0; | |
1429 | } | |
1430 | ||
1da177e4 | 1431 | /** |
710027a4 | 1432 | * generic_make_request - hand a buffer to its device driver for I/O |
1da177e4 LT |
1433 | * @bio: The bio describing the location in memory and on the device. |
1434 | * | |
1435 | * generic_make_request() is used to make I/O requests of block | |
1436 | * devices. It is passed a &struct bio, which describes the I/O that needs | |
1437 | * to be done. | |
1438 | * | |
1439 | * generic_make_request() does not return any status. The | |
1440 | * success/failure status of the request, along with notification of | |
1441 | * completion, is delivered asynchronously through the bio->bi_end_io | |
1442 | * function described (one day) else where. | |
1443 | * | |
1444 | * The caller of generic_make_request must make sure that bi_io_vec | |
1445 | * are set to describe the memory buffer, and that bi_dev and bi_sector are | |
1446 | * set to describe the device address, and the | |
1447 | * bi_end_io and optionally bi_private are set to describe how | |
1448 | * completion notification should be signaled. | |
1449 | * | |
1450 | * generic_make_request and the drivers it calls may use bi_next if this | |
1451 | * bio happens to be merged with someone else, and may change bi_dev and | |
1452 | * bi_sector for remaps as it sees fit. So the values of these fields | |
1453 | * should NOT be depended on after the call to generic_make_request. | |
1454 | */ | |
d89d8796 | 1455 | static inline void __generic_make_request(struct bio *bio) |
1da177e4 | 1456 | { |
165125e1 | 1457 | struct request_queue *q; |
5ddfe969 | 1458 | sector_t old_sector; |
1da177e4 | 1459 | int ret, nr_sectors = bio_sectors(bio); |
2056a782 | 1460 | dev_t old_dev; |
51fd77bd | 1461 | int err = -EIO; |
1da177e4 LT |
1462 | |
1463 | might_sleep(); | |
1da177e4 | 1464 | |
c07e2b41 JA |
1465 | if (bio_check_eod(bio, nr_sectors)) |
1466 | goto end_io; | |
1da177e4 LT |
1467 | |
1468 | /* | |
1469 | * Resolve the mapping until finished. (drivers are | |
1470 | * still free to implement/resolve their own stacking | |
1471 | * by explicitly returning 0) | |
1472 | * | |
1473 | * NOTE: we don't repeat the blk_size check for each new device. | |
1474 | * Stacking drivers are expected to know what they are doing. | |
1475 | */ | |
5ddfe969 | 1476 | old_sector = -1; |
2056a782 | 1477 | old_dev = 0; |
1da177e4 LT |
1478 | do { |
1479 | char b[BDEVNAME_SIZE]; | |
1480 | ||
1481 | q = bdev_get_queue(bio->bi_bdev); | |
a7384677 | 1482 | if (unlikely(!q)) { |
1da177e4 LT |
1483 | printk(KERN_ERR |
1484 | "generic_make_request: Trying to access " | |
1485 | "nonexistent block-device %s (%Lu)\n", | |
1486 | bdevname(bio->bi_bdev, b), | |
1487 | (long long) bio->bi_sector); | |
a7384677 | 1488 | goto end_io; |
1da177e4 LT |
1489 | } |
1490 | ||
7b6d91da | 1491 | if (unlikely(!(bio->bi_rw & REQ_DISCARD) && |
67efc925 | 1492 | nr_sectors > queue_max_hw_sectors(q))) { |
6728cb0e | 1493 | printk(KERN_ERR "bio too big device %s (%u > %u)\n", |
ae03bf63 MP |
1494 | bdevname(bio->bi_bdev, b), |
1495 | bio_sectors(bio), | |
1496 | queue_max_hw_sectors(q)); | |
1da177e4 LT |
1497 | goto end_io; |
1498 | } | |
1499 | ||
fde6ad22 | 1500 | if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) |
1da177e4 LT |
1501 | goto end_io; |
1502 | ||
c17bb495 AM |
1503 | if (should_fail_request(bio)) |
1504 | goto end_io; | |
1505 | ||
1da177e4 LT |
1506 | /* |
1507 | * If this device has partitions, remap block n | |
1508 | * of partition p to block n+start(p) of the disk. | |
1509 | */ | |
1510 | blk_partition_remap(bio); | |
1511 | ||
7ba1ba12 MP |
1512 | if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) |
1513 | goto end_io; | |
1514 | ||
5ddfe969 | 1515 | if (old_sector != -1) |
d07335e5 | 1516 | trace_block_bio_remap(q, bio, old_dev, old_sector); |
2056a782 | 1517 | |
5ddfe969 | 1518 | old_sector = bio->bi_sector; |
2056a782 JA |
1519 | old_dev = bio->bi_bdev->bd_dev; |
1520 | ||
c07e2b41 JA |
1521 | if (bio_check_eod(bio, nr_sectors)) |
1522 | goto end_io; | |
a7384677 | 1523 | |
1e87901e TH |
1524 | /* |
1525 | * Filter flush bio's early so that make_request based | |
1526 | * drivers without flush support don't have to worry | |
1527 | * about them. | |
1528 | */ | |
1529 | if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) { | |
1530 | bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA); | |
1531 | if (!nr_sectors) { | |
1532 | err = 0; | |
1533 | goto end_io; | |
1534 | } | |
1535 | } | |
1536 | ||
8d57a98c AH |
1537 | if ((bio->bi_rw & REQ_DISCARD) && |
1538 | (!blk_queue_discard(q) || | |
1539 | ((bio->bi_rw & REQ_SECURE) && | |
1540 | !blk_queue_secdiscard(q)))) { | |
51fd77bd JA |
1541 | err = -EOPNOTSUPP; |
1542 | goto end_io; | |
1543 | } | |
5ddfe969 | 1544 | |
e43473b7 VG |
1545 | blk_throtl_bio(q, &bio); |
1546 | ||
1547 | /* | |
1548 | * If bio = NULL, bio has been throttled and will be submitted | |
1549 | * later. | |
1550 | */ | |
1551 | if (!bio) | |
1552 | break; | |
1553 | ||
01edede4 MK |
1554 | trace_block_bio_queue(q, bio); |
1555 | ||
1da177e4 LT |
1556 | ret = q->make_request_fn(q, bio); |
1557 | } while (ret); | |
a7384677 TH |
1558 | |
1559 | return; | |
1560 | ||
1561 | end_io: | |
1562 | bio_endio(bio, err); | |
1da177e4 LT |
1563 | } |
1564 | ||
d89d8796 NB |
1565 | /* |
1566 | * We only want one ->make_request_fn to be active at a time, | |
1567 | * else stack usage with stacked devices could be a problem. | |
bddd87c7 | 1568 | * So use current->bio_list to keep a list of requests |
d89d8796 | 1569 | * submited by a make_request_fn function. |
bddd87c7 | 1570 | * current->bio_list is also used as a flag to say if |
d89d8796 NB |
1571 | * generic_make_request is currently active in this task or not. |
1572 | * If it is NULL, then no make_request is active. If it is non-NULL, | |
1573 | * then a make_request is active, and new requests should be added | |
1574 | * at the tail | |
1575 | */ | |
1576 | void generic_make_request(struct bio *bio) | |
1577 | { | |
bddd87c7 AM |
1578 | struct bio_list bio_list_on_stack; |
1579 | ||
1580 | if (current->bio_list) { | |
d89d8796 | 1581 | /* make_request is active */ |
bddd87c7 | 1582 | bio_list_add(current->bio_list, bio); |
d89d8796 NB |
1583 | return; |
1584 | } | |
1585 | /* following loop may be a bit non-obvious, and so deserves some | |
1586 | * explanation. | |
1587 | * Before entering the loop, bio->bi_next is NULL (as all callers | |
1588 | * ensure that) so we have a list with a single bio. | |
1589 | * We pretend that we have just taken it off a longer list, so | |
bddd87c7 AM |
1590 | * we assign bio_list to a pointer to the bio_list_on_stack, |
1591 | * thus initialising the bio_list of new bios to be | |
d89d8796 NB |
1592 | * added. __generic_make_request may indeed add some more bios |
1593 | * through a recursive call to generic_make_request. If it | |
1594 | * did, we find a non-NULL value in bio_list and re-enter the loop | |
1595 | * from the top. In this case we really did just take the bio | |
bddd87c7 AM |
1596 | * of the top of the list (no pretending) and so remove it from |
1597 | * bio_list, and call into __generic_make_request again. | |
d89d8796 NB |
1598 | * |
1599 | * The loop was structured like this to make only one call to | |
1600 | * __generic_make_request (which is important as it is large and | |
1601 | * inlined) and to keep the structure simple. | |
1602 | */ | |
1603 | BUG_ON(bio->bi_next); | |
bddd87c7 AM |
1604 | bio_list_init(&bio_list_on_stack); |
1605 | current->bio_list = &bio_list_on_stack; | |
d89d8796 | 1606 | do { |
d89d8796 | 1607 | __generic_make_request(bio); |
bddd87c7 | 1608 | bio = bio_list_pop(current->bio_list); |
d89d8796 | 1609 | } while (bio); |
bddd87c7 | 1610 | current->bio_list = NULL; /* deactivate */ |
d89d8796 | 1611 | } |
1da177e4 LT |
1612 | EXPORT_SYMBOL(generic_make_request); |
1613 | ||
1614 | /** | |
710027a4 | 1615 | * submit_bio - submit a bio to the block device layer for I/O |
1da177e4 LT |
1616 | * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) |
1617 | * @bio: The &struct bio which describes the I/O | |
1618 | * | |
1619 | * submit_bio() is very similar in purpose to generic_make_request(), and | |
1620 | * uses that function to do most of the work. Both are fairly rough | |
710027a4 | 1621 | * interfaces; @bio must be presetup and ready for I/O. |
1da177e4 LT |
1622 | * |
1623 | */ | |
1624 | void submit_bio(int rw, struct bio *bio) | |
1625 | { | |
1626 | int count = bio_sectors(bio); | |
1627 | ||
22e2c507 | 1628 | bio->bi_rw |= rw; |
1da177e4 | 1629 | |
bf2de6f5 JA |
1630 | /* |
1631 | * If it's a regular read/write or a barrier with data attached, | |
1632 | * go through the normal accounting stuff before submission. | |
1633 | */ | |
3ffb52e7 | 1634 | if (bio_has_data(bio) && !(rw & REQ_DISCARD)) { |
bf2de6f5 JA |
1635 | if (rw & WRITE) { |
1636 | count_vm_events(PGPGOUT, count); | |
1637 | } else { | |
1638 | task_io_account_read(bio->bi_size); | |
1639 | count_vm_events(PGPGIN, count); | |
1640 | } | |
1641 | ||
1642 | if (unlikely(block_dump)) { | |
1643 | char b[BDEVNAME_SIZE]; | |
8dcbdc74 | 1644 | printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", |
ba25f9dc | 1645 | current->comm, task_pid_nr(current), |
bf2de6f5 JA |
1646 | (rw & WRITE) ? "WRITE" : "READ", |
1647 | (unsigned long long)bio->bi_sector, | |
8dcbdc74 SM |
1648 | bdevname(bio->bi_bdev, b), |
1649 | count); | |
bf2de6f5 | 1650 | } |
1da177e4 LT |
1651 | } |
1652 | ||
1653 | generic_make_request(bio); | |
1654 | } | |
1da177e4 LT |
1655 | EXPORT_SYMBOL(submit_bio); |
1656 | ||
82124d60 KU |
1657 | /** |
1658 | * blk_rq_check_limits - Helper function to check a request for the queue limit | |
1659 | * @q: the queue | |
1660 | * @rq: the request being checked | |
1661 | * | |
1662 | * Description: | |
1663 | * @rq may have been made based on weaker limitations of upper-level queues | |
1664 | * in request stacking drivers, and it may violate the limitation of @q. | |
1665 | * Since the block layer and the underlying device driver trust @rq | |
1666 | * after it is inserted to @q, it should be checked against @q before | |
1667 | * the insertion using this generic function. | |
1668 | * | |
1669 | * This function should also be useful for request stacking drivers | |
eef35c2d | 1670 | * in some cases below, so export this function. |
82124d60 KU |
1671 | * Request stacking drivers like request-based dm may change the queue |
1672 | * limits while requests are in the queue (e.g. dm's table swapping). | |
1673 | * Such request stacking drivers should check those requests agaist | |
1674 | * the new queue limits again when they dispatch those requests, | |
1675 | * although such checkings are also done against the old queue limits | |
1676 | * when submitting requests. | |
1677 | */ | |
1678 | int blk_rq_check_limits(struct request_queue *q, struct request *rq) | |
1679 | { | |
3383977f S |
1680 | if (rq->cmd_flags & REQ_DISCARD) |
1681 | return 0; | |
1682 | ||
ae03bf63 MP |
1683 | if (blk_rq_sectors(rq) > queue_max_sectors(q) || |
1684 | blk_rq_bytes(rq) > queue_max_hw_sectors(q) << 9) { | |
82124d60 KU |
1685 | printk(KERN_ERR "%s: over max size limit.\n", __func__); |
1686 | return -EIO; | |
1687 | } | |
1688 | ||
1689 | /* | |
1690 | * queue's settings related to segment counting like q->bounce_pfn | |
1691 | * may differ from that of other stacking queues. | |
1692 | * Recalculate it to check the request correctly on this queue's | |
1693 | * limitation. | |
1694 | */ | |
1695 | blk_recalc_rq_segments(rq); | |
8a78362c | 1696 | if (rq->nr_phys_segments > queue_max_segments(q)) { |
82124d60 KU |
1697 | printk(KERN_ERR "%s: over max segments limit.\n", __func__); |
1698 | return -EIO; | |
1699 | } | |
1700 | ||
1701 | return 0; | |
1702 | } | |
1703 | EXPORT_SYMBOL_GPL(blk_rq_check_limits); | |
1704 | ||
1705 | /** | |
1706 | * blk_insert_cloned_request - Helper for stacking drivers to submit a request | |
1707 | * @q: the queue to submit the request | |
1708 | * @rq: the request being queued | |
1709 | */ | |
1710 | int blk_insert_cloned_request(struct request_queue *q, struct request *rq) | |
1711 | { | |
1712 | unsigned long flags; | |
1713 | ||
1714 | if (blk_rq_check_limits(q, rq)) | |
1715 | return -EIO; | |
1716 | ||
1717 | #ifdef CONFIG_FAIL_MAKE_REQUEST | |
1718 | if (rq->rq_disk && rq->rq_disk->part0.make_it_fail && | |
1719 | should_fail(&fail_make_request, blk_rq_bytes(rq))) | |
1720 | return -EIO; | |
1721 | #endif | |
1722 | ||
1723 | spin_lock_irqsave(q->queue_lock, flags); | |
1724 | ||
1725 | /* | |
1726 | * Submitting request must be dequeued before calling this function | |
1727 | * because it will be linked to another request_queue | |
1728 | */ | |
1729 | BUG_ON(blk_queued_rq(rq)); | |
1730 | ||
73c10101 | 1731 | add_acct_request(q, rq, ELEVATOR_INSERT_BACK); |
82124d60 KU |
1732 | spin_unlock_irqrestore(q->queue_lock, flags); |
1733 | ||
1734 | return 0; | |
1735 | } | |
1736 | EXPORT_SYMBOL_GPL(blk_insert_cloned_request); | |
1737 | ||
80a761fd TH |
1738 | /** |
1739 | * blk_rq_err_bytes - determine number of bytes till the next failure boundary | |
1740 | * @rq: request to examine | |
1741 | * | |
1742 | * Description: | |
1743 | * A request could be merge of IOs which require different failure | |
1744 | * handling. This function determines the number of bytes which | |
1745 | * can be failed from the beginning of the request without | |
1746 | * crossing into area which need to be retried further. | |
1747 | * | |
1748 | * Return: | |
1749 | * The number of bytes to fail. | |
1750 | * | |
1751 | * Context: | |
1752 | * queue_lock must be held. | |
1753 | */ | |
1754 | unsigned int blk_rq_err_bytes(const struct request *rq) | |
1755 | { | |
1756 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
1757 | unsigned int bytes = 0; | |
1758 | struct bio *bio; | |
1759 | ||
1760 | if (!(rq->cmd_flags & REQ_MIXED_MERGE)) | |
1761 | return blk_rq_bytes(rq); | |
1762 | ||
1763 | /* | |
1764 | * Currently the only 'mixing' which can happen is between | |
1765 | * different fastfail types. We can safely fail portions | |
1766 | * which have all the failfast bits that the first one has - | |
1767 | * the ones which are at least as eager to fail as the first | |
1768 | * one. | |
1769 | */ | |
1770 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
1771 | if ((bio->bi_rw & ff) != ff) | |
1772 | break; | |
1773 | bytes += bio->bi_size; | |
1774 | } | |
1775 | ||
1776 | /* this could lead to infinite loop */ | |
1777 | BUG_ON(blk_rq_bytes(rq) && !bytes); | |
1778 | return bytes; | |
1779 | } | |
1780 | EXPORT_SYMBOL_GPL(blk_rq_err_bytes); | |
1781 | ||
bc58ba94 JA |
1782 | static void blk_account_io_completion(struct request *req, unsigned int bytes) |
1783 | { | |
c2553b58 | 1784 | if (blk_do_io_stat(req)) { |
bc58ba94 JA |
1785 | const int rw = rq_data_dir(req); |
1786 | struct hd_struct *part; | |
1787 | int cpu; | |
1788 | ||
1789 | cpu = part_stat_lock(); | |
09e099d4 | 1790 | part = req->part; |
bc58ba94 JA |
1791 | part_stat_add(cpu, part, sectors[rw], bytes >> 9); |
1792 | part_stat_unlock(); | |
1793 | } | |
1794 | } | |
1795 | ||
1796 | static void blk_account_io_done(struct request *req) | |
1797 | { | |
bc58ba94 | 1798 | /* |
dd4c133f TH |
1799 | * Account IO completion. flush_rq isn't accounted as a |
1800 | * normal IO on queueing nor completion. Accounting the | |
1801 | * containing request is enough. | |
bc58ba94 | 1802 | */ |
414b4ff5 | 1803 | if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) { |
bc58ba94 JA |
1804 | unsigned long duration = jiffies - req->start_time; |
1805 | const int rw = rq_data_dir(req); | |
1806 | struct hd_struct *part; | |
1807 | int cpu; | |
1808 | ||
1809 | cpu = part_stat_lock(); | |
09e099d4 | 1810 | part = req->part; |
bc58ba94 JA |
1811 | |
1812 | part_stat_inc(cpu, part, ios[rw]); | |
1813 | part_stat_add(cpu, part, ticks[rw], duration); | |
1814 | part_round_stats(cpu, part); | |
316d315b | 1815 | part_dec_in_flight(part, rw); |
bc58ba94 | 1816 | |
6c23a968 | 1817 | hd_struct_put(part); |
bc58ba94 JA |
1818 | part_stat_unlock(); |
1819 | } | |
1820 | } | |
1821 | ||
3bcddeac | 1822 | /** |
9934c8c0 TH |
1823 | * blk_peek_request - peek at the top of a request queue |
1824 | * @q: request queue to peek at | |
1825 | * | |
1826 | * Description: | |
1827 | * Return the request at the top of @q. The returned request | |
1828 | * should be started using blk_start_request() before LLD starts | |
1829 | * processing it. | |
1830 | * | |
1831 | * Return: | |
1832 | * Pointer to the request at the top of @q if available. Null | |
1833 | * otherwise. | |
1834 | * | |
1835 | * Context: | |
1836 | * queue_lock must be held. | |
1837 | */ | |
1838 | struct request *blk_peek_request(struct request_queue *q) | |
158dbda0 TH |
1839 | { |
1840 | struct request *rq; | |
1841 | int ret; | |
1842 | ||
1843 | while ((rq = __elv_next_request(q)) != NULL) { | |
1844 | if (!(rq->cmd_flags & REQ_STARTED)) { | |
1845 | /* | |
1846 | * This is the first time the device driver | |
1847 | * sees this request (possibly after | |
1848 | * requeueing). Notify IO scheduler. | |
1849 | */ | |
33659ebb | 1850 | if (rq->cmd_flags & REQ_SORTED) |
158dbda0 TH |
1851 | elv_activate_rq(q, rq); |
1852 | ||
1853 | /* | |
1854 | * just mark as started even if we don't start | |
1855 | * it, a request that has been delayed should | |
1856 | * not be passed by new incoming requests | |
1857 | */ | |
1858 | rq->cmd_flags |= REQ_STARTED; | |
1859 | trace_block_rq_issue(q, rq); | |
1860 | } | |
1861 | ||
1862 | if (!q->boundary_rq || q->boundary_rq == rq) { | |
1863 | q->end_sector = rq_end_sector(rq); | |
1864 | q->boundary_rq = NULL; | |
1865 | } | |
1866 | ||
1867 | if (rq->cmd_flags & REQ_DONTPREP) | |
1868 | break; | |
1869 | ||
2e46e8b2 | 1870 | if (q->dma_drain_size && blk_rq_bytes(rq)) { |
158dbda0 TH |
1871 | /* |
1872 | * make sure space for the drain appears we | |
1873 | * know we can do this because max_hw_segments | |
1874 | * has been adjusted to be one fewer than the | |
1875 | * device can handle | |
1876 | */ | |
1877 | rq->nr_phys_segments++; | |
1878 | } | |
1879 | ||
1880 | if (!q->prep_rq_fn) | |
1881 | break; | |
1882 | ||
1883 | ret = q->prep_rq_fn(q, rq); | |
1884 | if (ret == BLKPREP_OK) { | |
1885 | break; | |
1886 | } else if (ret == BLKPREP_DEFER) { | |
1887 | /* | |
1888 | * the request may have been (partially) prepped. | |
1889 | * we need to keep this request in the front to | |
1890 | * avoid resource deadlock. REQ_STARTED will | |
1891 | * prevent other fs requests from passing this one. | |
1892 | */ | |
2e46e8b2 | 1893 | if (q->dma_drain_size && blk_rq_bytes(rq) && |
158dbda0 TH |
1894 | !(rq->cmd_flags & REQ_DONTPREP)) { |
1895 | /* | |
1896 | * remove the space for the drain we added | |
1897 | * so that we don't add it again | |
1898 | */ | |
1899 | --rq->nr_phys_segments; | |
1900 | } | |
1901 | ||
1902 | rq = NULL; | |
1903 | break; | |
1904 | } else if (ret == BLKPREP_KILL) { | |
1905 | rq->cmd_flags |= REQ_QUIET; | |
c143dc90 JB |
1906 | /* |
1907 | * Mark this request as started so we don't trigger | |
1908 | * any debug logic in the end I/O path. | |
1909 | */ | |
1910 | blk_start_request(rq); | |
40cbbb78 | 1911 | __blk_end_request_all(rq, -EIO); |
158dbda0 TH |
1912 | } else { |
1913 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); | |
1914 | break; | |
1915 | } | |
1916 | } | |
1917 | ||
1918 | return rq; | |
1919 | } | |
9934c8c0 | 1920 | EXPORT_SYMBOL(blk_peek_request); |
158dbda0 | 1921 | |
9934c8c0 | 1922 | void blk_dequeue_request(struct request *rq) |
158dbda0 | 1923 | { |
9934c8c0 TH |
1924 | struct request_queue *q = rq->q; |
1925 | ||
158dbda0 TH |
1926 | BUG_ON(list_empty(&rq->queuelist)); |
1927 | BUG_ON(ELV_ON_HASH(rq)); | |
1928 | ||
1929 | list_del_init(&rq->queuelist); | |
1930 | ||
1931 | /* | |
1932 | * the time frame between a request being removed from the lists | |
1933 | * and to it is freed is accounted as io that is in progress at | |
1934 | * the driver side. | |
1935 | */ | |
9195291e | 1936 | if (blk_account_rq(rq)) { |
0a7ae2ff | 1937 | q->in_flight[rq_is_sync(rq)]++; |
9195291e DS |
1938 | set_io_start_time_ns(rq); |
1939 | } | |
158dbda0 TH |
1940 | } |
1941 | ||
9934c8c0 TH |
1942 | /** |
1943 | * blk_start_request - start request processing on the driver | |
1944 | * @req: request to dequeue | |
1945 | * | |
1946 | * Description: | |
1947 | * Dequeue @req and start timeout timer on it. This hands off the | |
1948 | * request to the driver. | |
1949 | * | |
1950 | * Block internal functions which don't want to start timer should | |
1951 | * call blk_dequeue_request(). | |
1952 | * | |
1953 | * Context: | |
1954 | * queue_lock must be held. | |
1955 | */ | |
1956 | void blk_start_request(struct request *req) | |
1957 | { | |
1958 | blk_dequeue_request(req); | |
1959 | ||
1960 | /* | |
5f49f631 TH |
1961 | * We are now handing the request to the hardware, initialize |
1962 | * resid_len to full count and add the timeout handler. | |
9934c8c0 | 1963 | */ |
5f49f631 | 1964 | req->resid_len = blk_rq_bytes(req); |
dbb66c4b FT |
1965 | if (unlikely(blk_bidi_rq(req))) |
1966 | req->next_rq->resid_len = blk_rq_bytes(req->next_rq); | |
1967 | ||
9934c8c0 TH |
1968 | blk_add_timer(req); |
1969 | } | |
1970 | EXPORT_SYMBOL(blk_start_request); | |
1971 | ||
1972 | /** | |
1973 | * blk_fetch_request - fetch a request from a request queue | |
1974 | * @q: request queue to fetch a request from | |
1975 | * | |
1976 | * Description: | |
1977 | * Return the request at the top of @q. The request is started on | |
1978 | * return and LLD can start processing it immediately. | |
1979 | * | |
1980 | * Return: | |
1981 | * Pointer to the request at the top of @q if available. Null | |
1982 | * otherwise. | |
1983 | * | |
1984 | * Context: | |
1985 | * queue_lock must be held. | |
1986 | */ | |
1987 | struct request *blk_fetch_request(struct request_queue *q) | |
1988 | { | |
1989 | struct request *rq; | |
1990 | ||
1991 | rq = blk_peek_request(q); | |
1992 | if (rq) | |
1993 | blk_start_request(rq); | |
1994 | return rq; | |
1995 | } | |
1996 | EXPORT_SYMBOL(blk_fetch_request); | |
1997 | ||
3bcddeac | 1998 | /** |
2e60e022 | 1999 | * blk_update_request - Special helper function for request stacking drivers |
8ebf9756 | 2000 | * @req: the request being processed |
710027a4 | 2001 | * @error: %0 for success, < %0 for error |
8ebf9756 | 2002 | * @nr_bytes: number of bytes to complete @req |
3bcddeac KU |
2003 | * |
2004 | * Description: | |
8ebf9756 RD |
2005 | * Ends I/O on a number of bytes attached to @req, but doesn't complete |
2006 | * the request structure even if @req doesn't have leftover. | |
2007 | * If @req has leftover, sets it up for the next range of segments. | |
2e60e022 TH |
2008 | * |
2009 | * This special helper function is only for request stacking drivers | |
2010 | * (e.g. request-based dm) so that they can handle partial completion. | |
2011 | * Actual device drivers should use blk_end_request instead. | |
2012 | * | |
2013 | * Passing the result of blk_rq_bytes() as @nr_bytes guarantees | |
2014 | * %false return from this function. | |
3bcddeac KU |
2015 | * |
2016 | * Return: | |
2e60e022 TH |
2017 | * %false - this request doesn't have any more data |
2018 | * %true - this request has more data | |
3bcddeac | 2019 | **/ |
2e60e022 | 2020 | bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) |
1da177e4 | 2021 | { |
5450d3e1 | 2022 | int total_bytes, bio_nbytes, next_idx = 0; |
1da177e4 LT |
2023 | struct bio *bio; |
2024 | ||
2e60e022 TH |
2025 | if (!req->bio) |
2026 | return false; | |
2027 | ||
5f3ea37c | 2028 | trace_block_rq_complete(req->q, req); |
2056a782 | 2029 | |
1da177e4 | 2030 | /* |
6f41469c TH |
2031 | * For fs requests, rq is just carrier of independent bio's |
2032 | * and each partial completion should be handled separately. | |
2033 | * Reset per-request error on each partial completion. | |
2034 | * | |
2035 | * TODO: tj: This is too subtle. It would be better to let | |
2036 | * low level drivers do what they see fit. | |
1da177e4 | 2037 | */ |
33659ebb | 2038 | if (req->cmd_type == REQ_TYPE_FS) |
1da177e4 LT |
2039 | req->errors = 0; |
2040 | ||
33659ebb CH |
2041 | if (error && req->cmd_type == REQ_TYPE_FS && |
2042 | !(req->cmd_flags & REQ_QUIET)) { | |
79775567 HR |
2043 | char *error_type; |
2044 | ||
2045 | switch (error) { | |
2046 | case -ENOLINK: | |
2047 | error_type = "recoverable transport"; | |
2048 | break; | |
2049 | case -EREMOTEIO: | |
2050 | error_type = "critical target"; | |
2051 | break; | |
2052 | case -EBADE: | |
2053 | error_type = "critical nexus"; | |
2054 | break; | |
2055 | case -EIO: | |
2056 | default: | |
2057 | error_type = "I/O"; | |
2058 | break; | |
2059 | } | |
2060 | printk(KERN_ERR "end_request: %s error, dev %s, sector %llu\n", | |
2061 | error_type, req->rq_disk ? req->rq_disk->disk_name : "?", | |
2062 | (unsigned long long)blk_rq_pos(req)); | |
1da177e4 LT |
2063 | } |
2064 | ||
bc58ba94 | 2065 | blk_account_io_completion(req, nr_bytes); |
d72d904a | 2066 | |
1da177e4 LT |
2067 | total_bytes = bio_nbytes = 0; |
2068 | while ((bio = req->bio) != NULL) { | |
2069 | int nbytes; | |
2070 | ||
2071 | if (nr_bytes >= bio->bi_size) { | |
2072 | req->bio = bio->bi_next; | |
2073 | nbytes = bio->bi_size; | |
5bb23a68 | 2074 | req_bio_endio(req, bio, nbytes, error); |
1da177e4 LT |
2075 | next_idx = 0; |
2076 | bio_nbytes = 0; | |
2077 | } else { | |
2078 | int idx = bio->bi_idx + next_idx; | |
2079 | ||
af498d7f | 2080 | if (unlikely(idx >= bio->bi_vcnt)) { |
1da177e4 | 2081 | blk_dump_rq_flags(req, "__end_that"); |
6728cb0e | 2082 | printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n", |
af498d7f | 2083 | __func__, idx, bio->bi_vcnt); |
1da177e4 LT |
2084 | break; |
2085 | } | |
2086 | ||
2087 | nbytes = bio_iovec_idx(bio, idx)->bv_len; | |
2088 | BIO_BUG_ON(nbytes > bio->bi_size); | |
2089 | ||
2090 | /* | |
2091 | * not a complete bvec done | |
2092 | */ | |
2093 | if (unlikely(nbytes > nr_bytes)) { | |
2094 | bio_nbytes += nr_bytes; | |
2095 | total_bytes += nr_bytes; | |
2096 | break; | |
2097 | } | |
2098 | ||
2099 | /* | |
2100 | * advance to the next vector | |
2101 | */ | |
2102 | next_idx++; | |
2103 | bio_nbytes += nbytes; | |
2104 | } | |
2105 | ||
2106 | total_bytes += nbytes; | |
2107 | nr_bytes -= nbytes; | |
2108 | ||
6728cb0e JA |
2109 | bio = req->bio; |
2110 | if (bio) { | |
1da177e4 LT |
2111 | /* |
2112 | * end more in this run, or just return 'not-done' | |
2113 | */ | |
2114 | if (unlikely(nr_bytes <= 0)) | |
2115 | break; | |
2116 | } | |
2117 | } | |
2118 | ||
2119 | /* | |
2120 | * completely done | |
2121 | */ | |
2e60e022 TH |
2122 | if (!req->bio) { |
2123 | /* | |
2124 | * Reset counters so that the request stacking driver | |
2125 | * can find how many bytes remain in the request | |
2126 | * later. | |
2127 | */ | |
a2dec7b3 | 2128 | req->__data_len = 0; |
2e60e022 TH |
2129 | return false; |
2130 | } | |
1da177e4 LT |
2131 | |
2132 | /* | |
2133 | * if the request wasn't completed, update state | |
2134 | */ | |
2135 | if (bio_nbytes) { | |
5bb23a68 | 2136 | req_bio_endio(req, bio, bio_nbytes, error); |
1da177e4 LT |
2137 | bio->bi_idx += next_idx; |
2138 | bio_iovec(bio)->bv_offset += nr_bytes; | |
2139 | bio_iovec(bio)->bv_len -= nr_bytes; | |
2140 | } | |
2141 | ||
a2dec7b3 | 2142 | req->__data_len -= total_bytes; |
2e46e8b2 TH |
2143 | req->buffer = bio_data(req->bio); |
2144 | ||
2145 | /* update sector only for requests with clear definition of sector */ | |
33659ebb | 2146 | if (req->cmd_type == REQ_TYPE_FS || (req->cmd_flags & REQ_DISCARD)) |
a2dec7b3 | 2147 | req->__sector += total_bytes >> 9; |
2e46e8b2 | 2148 | |
80a761fd TH |
2149 | /* mixed attributes always follow the first bio */ |
2150 | if (req->cmd_flags & REQ_MIXED_MERGE) { | |
2151 | req->cmd_flags &= ~REQ_FAILFAST_MASK; | |
2152 | req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK; | |
2153 | } | |
2154 | ||
2e46e8b2 TH |
2155 | /* |
2156 | * If total number of sectors is less than the first segment | |
2157 | * size, something has gone terribly wrong. | |
2158 | */ | |
2159 | if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { | |
8182924b | 2160 | blk_dump_rq_flags(req, "request botched"); |
a2dec7b3 | 2161 | req->__data_len = blk_rq_cur_bytes(req); |
2e46e8b2 TH |
2162 | } |
2163 | ||
2164 | /* recalculate the number of segments */ | |
1da177e4 | 2165 | blk_recalc_rq_segments(req); |
2e46e8b2 | 2166 | |
2e60e022 | 2167 | return true; |
1da177e4 | 2168 | } |
2e60e022 | 2169 | EXPORT_SYMBOL_GPL(blk_update_request); |
1da177e4 | 2170 | |
2e60e022 TH |
2171 | static bool blk_update_bidi_request(struct request *rq, int error, |
2172 | unsigned int nr_bytes, | |
2173 | unsigned int bidi_bytes) | |
5efccd17 | 2174 | { |
2e60e022 TH |
2175 | if (blk_update_request(rq, error, nr_bytes)) |
2176 | return true; | |
5efccd17 | 2177 | |
2e60e022 TH |
2178 | /* Bidi request must be completed as a whole */ |
2179 | if (unlikely(blk_bidi_rq(rq)) && | |
2180 | blk_update_request(rq->next_rq, error, bidi_bytes)) | |
2181 | return true; | |
5efccd17 | 2182 | |
e2e1a148 JA |
2183 | if (blk_queue_add_random(rq->q)) |
2184 | add_disk_randomness(rq->rq_disk); | |
2e60e022 TH |
2185 | |
2186 | return false; | |
1da177e4 LT |
2187 | } |
2188 | ||
28018c24 JB |
2189 | /** |
2190 | * blk_unprep_request - unprepare a request | |
2191 | * @req: the request | |
2192 | * | |
2193 | * This function makes a request ready for complete resubmission (or | |
2194 | * completion). It happens only after all error handling is complete, | |
2195 | * so represents the appropriate moment to deallocate any resources | |
2196 | * that were allocated to the request in the prep_rq_fn. The queue | |
2197 | * lock is held when calling this. | |
2198 | */ | |
2199 | void blk_unprep_request(struct request *req) | |
2200 | { | |
2201 | struct request_queue *q = req->q; | |
2202 | ||
2203 | req->cmd_flags &= ~REQ_DONTPREP; | |
2204 | if (q->unprep_rq_fn) | |
2205 | q->unprep_rq_fn(q, req); | |
2206 | } | |
2207 | EXPORT_SYMBOL_GPL(blk_unprep_request); | |
2208 | ||
1da177e4 LT |
2209 | /* |
2210 | * queue lock must be held | |
2211 | */ | |
2e60e022 | 2212 | static void blk_finish_request(struct request *req, int error) |
1da177e4 | 2213 | { |
b8286239 KU |
2214 | if (blk_rq_tagged(req)) |
2215 | blk_queue_end_tag(req->q, req); | |
2216 | ||
ba396a6c | 2217 | BUG_ON(blk_queued_rq(req)); |
1da177e4 | 2218 | |
33659ebb | 2219 | if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS) |
31373d09 | 2220 | laptop_io_completion(&req->q->backing_dev_info); |
1da177e4 | 2221 | |
e78042e5 MA |
2222 | blk_delete_timer(req); |
2223 | ||
28018c24 JB |
2224 | if (req->cmd_flags & REQ_DONTPREP) |
2225 | blk_unprep_request(req); | |
2226 | ||
2227 | ||
bc58ba94 | 2228 | blk_account_io_done(req); |
b8286239 | 2229 | |
1da177e4 | 2230 | if (req->end_io) |
8ffdc655 | 2231 | req->end_io(req, error); |
b8286239 KU |
2232 | else { |
2233 | if (blk_bidi_rq(req)) | |
2234 | __blk_put_request(req->next_rq->q, req->next_rq); | |
2235 | ||
1da177e4 | 2236 | __blk_put_request(req->q, req); |
b8286239 | 2237 | } |
1da177e4 LT |
2238 | } |
2239 | ||
3b11313a | 2240 | /** |
2e60e022 TH |
2241 | * blk_end_bidi_request - Complete a bidi request |
2242 | * @rq: the request to complete | |
2243 | * @error: %0 for success, < %0 for error | |
2244 | * @nr_bytes: number of bytes to complete @rq | |
2245 | * @bidi_bytes: number of bytes to complete @rq->next_rq | |
a0cd1285 JA |
2246 | * |
2247 | * Description: | |
e3a04fe3 | 2248 | * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. |
2e60e022 TH |
2249 | * Drivers that supports bidi can safely call this member for any |
2250 | * type of request, bidi or uni. In the later case @bidi_bytes is | |
2251 | * just ignored. | |
336cdb40 KU |
2252 | * |
2253 | * Return: | |
2e60e022 TH |
2254 | * %false - we are done with this request |
2255 | * %true - still buffers pending for this request | |
a0cd1285 | 2256 | **/ |
b1f74493 | 2257 | static bool blk_end_bidi_request(struct request *rq, int error, |
32fab448 KU |
2258 | unsigned int nr_bytes, unsigned int bidi_bytes) |
2259 | { | |
336cdb40 | 2260 | struct request_queue *q = rq->q; |
2e60e022 | 2261 | unsigned long flags; |
32fab448 | 2262 | |
2e60e022 TH |
2263 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
2264 | return true; | |
32fab448 | 2265 | |
336cdb40 | 2266 | spin_lock_irqsave(q->queue_lock, flags); |
2e60e022 | 2267 | blk_finish_request(rq, error); |
336cdb40 KU |
2268 | spin_unlock_irqrestore(q->queue_lock, flags); |
2269 | ||
2e60e022 | 2270 | return false; |
32fab448 KU |
2271 | } |
2272 | ||
336cdb40 | 2273 | /** |
2e60e022 TH |
2274 | * __blk_end_bidi_request - Complete a bidi request with queue lock held |
2275 | * @rq: the request to complete | |
710027a4 | 2276 | * @error: %0 for success, < %0 for error |
e3a04fe3 KU |
2277 | * @nr_bytes: number of bytes to complete @rq |
2278 | * @bidi_bytes: number of bytes to complete @rq->next_rq | |
336cdb40 KU |
2279 | * |
2280 | * Description: | |
2e60e022 TH |
2281 | * Identical to blk_end_bidi_request() except that queue lock is |
2282 | * assumed to be locked on entry and remains so on return. | |
336cdb40 KU |
2283 | * |
2284 | * Return: | |
2e60e022 TH |
2285 | * %false - we are done with this request |
2286 | * %true - still buffers pending for this request | |
336cdb40 | 2287 | **/ |
b1f74493 FT |
2288 | static bool __blk_end_bidi_request(struct request *rq, int error, |
2289 | unsigned int nr_bytes, unsigned int bidi_bytes) | |
336cdb40 | 2290 | { |
2e60e022 TH |
2291 | if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
2292 | return true; | |
336cdb40 | 2293 | |
2e60e022 | 2294 | blk_finish_request(rq, error); |
336cdb40 | 2295 | |
2e60e022 | 2296 | return false; |
336cdb40 | 2297 | } |
e19a3ab0 KU |
2298 | |
2299 | /** | |
2300 | * blk_end_request - Helper function for drivers to complete the request. | |
2301 | * @rq: the request being processed | |
710027a4 | 2302 | * @error: %0 for success, < %0 for error |
e19a3ab0 KU |
2303 | * @nr_bytes: number of bytes to complete |
2304 | * | |
2305 | * Description: | |
2306 | * Ends I/O on a number of bytes attached to @rq. | |
2307 | * If @rq has leftover, sets it up for the next range of segments. | |
2308 | * | |
2309 | * Return: | |
b1f74493 FT |
2310 | * %false - we are done with this request |
2311 | * %true - still buffers pending for this request | |
e19a3ab0 | 2312 | **/ |
b1f74493 | 2313 | bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
e19a3ab0 | 2314 | { |
b1f74493 | 2315 | return blk_end_bidi_request(rq, error, nr_bytes, 0); |
e19a3ab0 | 2316 | } |
56ad1740 | 2317 | EXPORT_SYMBOL(blk_end_request); |
336cdb40 KU |
2318 | |
2319 | /** | |
b1f74493 FT |
2320 | * blk_end_request_all - Helper function for drives to finish the request. |
2321 | * @rq: the request to finish | |
8ebf9756 | 2322 | * @error: %0 for success, < %0 for error |
336cdb40 KU |
2323 | * |
2324 | * Description: | |
b1f74493 FT |
2325 | * Completely finish @rq. |
2326 | */ | |
2327 | void blk_end_request_all(struct request *rq, int error) | |
336cdb40 | 2328 | { |
b1f74493 FT |
2329 | bool pending; |
2330 | unsigned int bidi_bytes = 0; | |
336cdb40 | 2331 | |
b1f74493 FT |
2332 | if (unlikely(blk_bidi_rq(rq))) |
2333 | bidi_bytes = blk_rq_bytes(rq->next_rq); | |
336cdb40 | 2334 | |
b1f74493 FT |
2335 | pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); |
2336 | BUG_ON(pending); | |
2337 | } | |
56ad1740 | 2338 | EXPORT_SYMBOL(blk_end_request_all); |
336cdb40 | 2339 | |
b1f74493 FT |
2340 | /** |
2341 | * blk_end_request_cur - Helper function to finish the current request chunk. | |
2342 | * @rq: the request to finish the current chunk for | |
8ebf9756 | 2343 | * @error: %0 for success, < %0 for error |
b1f74493 FT |
2344 | * |
2345 | * Description: | |
2346 | * Complete the current consecutively mapped chunk from @rq. | |
2347 | * | |
2348 | * Return: | |
2349 | * %false - we are done with this request | |
2350 | * %true - still buffers pending for this request | |
2351 | */ | |
2352 | bool blk_end_request_cur(struct request *rq, int error) | |
2353 | { | |
2354 | return blk_end_request(rq, error, blk_rq_cur_bytes(rq)); | |
336cdb40 | 2355 | } |
56ad1740 | 2356 | EXPORT_SYMBOL(blk_end_request_cur); |
336cdb40 | 2357 | |
80a761fd TH |
2358 | /** |
2359 | * blk_end_request_err - Finish a request till the next failure boundary. | |
2360 | * @rq: the request to finish till the next failure boundary for | |
2361 | * @error: must be negative errno | |
2362 | * | |
2363 | * Description: | |
2364 | * Complete @rq till the next failure boundary. | |
2365 | * | |
2366 | * Return: | |
2367 | * %false - we are done with this request | |
2368 | * %true - still buffers pending for this request | |
2369 | */ | |
2370 | bool blk_end_request_err(struct request *rq, int error) | |
2371 | { | |
2372 | WARN_ON(error >= 0); | |
2373 | return blk_end_request(rq, error, blk_rq_err_bytes(rq)); | |
2374 | } | |
2375 | EXPORT_SYMBOL_GPL(blk_end_request_err); | |
2376 | ||
e3a04fe3 | 2377 | /** |
b1f74493 FT |
2378 | * __blk_end_request - Helper function for drivers to complete the request. |
2379 | * @rq: the request being processed | |
2380 | * @error: %0 for success, < %0 for error | |
2381 | * @nr_bytes: number of bytes to complete | |
e3a04fe3 KU |
2382 | * |
2383 | * Description: | |
b1f74493 | 2384 | * Must be called with queue lock held unlike blk_end_request(). |
e3a04fe3 KU |
2385 | * |
2386 | * Return: | |
b1f74493 FT |
2387 | * %false - we are done with this request |
2388 | * %true - still buffers pending for this request | |
e3a04fe3 | 2389 | **/ |
b1f74493 | 2390 | bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
e3a04fe3 | 2391 | { |
b1f74493 | 2392 | return __blk_end_bidi_request(rq, error, nr_bytes, 0); |
e3a04fe3 | 2393 | } |
56ad1740 | 2394 | EXPORT_SYMBOL(__blk_end_request); |
e3a04fe3 | 2395 | |
32fab448 | 2396 | /** |
b1f74493 FT |
2397 | * __blk_end_request_all - Helper function for drives to finish the request. |
2398 | * @rq: the request to finish | |
8ebf9756 | 2399 | * @error: %0 for success, < %0 for error |
32fab448 KU |
2400 | * |
2401 | * Description: | |
b1f74493 | 2402 | * Completely finish @rq. Must be called with queue lock held. |
32fab448 | 2403 | */ |
b1f74493 | 2404 | void __blk_end_request_all(struct request *rq, int error) |
32fab448 | 2405 | { |
b1f74493 FT |
2406 | bool pending; |
2407 | unsigned int bidi_bytes = 0; | |
2408 | ||
2409 | if (unlikely(blk_bidi_rq(rq))) | |
2410 | bidi_bytes = blk_rq_bytes(rq->next_rq); | |
2411 | ||
2412 | pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); | |
2413 | BUG_ON(pending); | |
32fab448 | 2414 | } |
56ad1740 | 2415 | EXPORT_SYMBOL(__blk_end_request_all); |
32fab448 | 2416 | |
e19a3ab0 | 2417 | /** |
b1f74493 FT |
2418 | * __blk_end_request_cur - Helper function to finish the current request chunk. |
2419 | * @rq: the request to finish the current chunk for | |
8ebf9756 | 2420 | * @error: %0 for success, < %0 for error |
e19a3ab0 KU |
2421 | * |
2422 | * Description: | |
b1f74493 FT |
2423 | * Complete the current consecutively mapped chunk from @rq. Must |
2424 | * be called with queue lock held. | |
e19a3ab0 KU |
2425 | * |
2426 | * Return: | |
b1f74493 FT |
2427 | * %false - we are done with this request |
2428 | * %true - still buffers pending for this request | |
2429 | */ | |
2430 | bool __blk_end_request_cur(struct request *rq, int error) | |
e19a3ab0 | 2431 | { |
b1f74493 | 2432 | return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); |
e19a3ab0 | 2433 | } |
56ad1740 | 2434 | EXPORT_SYMBOL(__blk_end_request_cur); |
e19a3ab0 | 2435 | |
80a761fd TH |
2436 | /** |
2437 | * __blk_end_request_err - Finish a request till the next failure boundary. | |
2438 | * @rq: the request to finish till the next failure boundary for | |
2439 | * @error: must be negative errno | |
2440 | * | |
2441 | * Description: | |
2442 | * Complete @rq till the next failure boundary. Must be called | |
2443 | * with queue lock held. | |
2444 | * | |
2445 | * Return: | |
2446 | * %false - we are done with this request | |
2447 | * %true - still buffers pending for this request | |
2448 | */ | |
2449 | bool __blk_end_request_err(struct request *rq, int error) | |
2450 | { | |
2451 | WARN_ON(error >= 0); | |
2452 | return __blk_end_request(rq, error, blk_rq_err_bytes(rq)); | |
2453 | } | |
2454 | EXPORT_SYMBOL_GPL(__blk_end_request_err); | |
2455 | ||
86db1e29 JA |
2456 | void blk_rq_bio_prep(struct request_queue *q, struct request *rq, |
2457 | struct bio *bio) | |
1da177e4 | 2458 | { |
a82afdfc | 2459 | /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */ |
7b6d91da | 2460 | rq->cmd_flags |= bio->bi_rw & REQ_WRITE; |
1da177e4 | 2461 | |
fb2dce86 DW |
2462 | if (bio_has_data(bio)) { |
2463 | rq->nr_phys_segments = bio_phys_segments(q, bio); | |
fb2dce86 DW |
2464 | rq->buffer = bio_data(bio); |
2465 | } | |
a2dec7b3 | 2466 | rq->__data_len = bio->bi_size; |
1da177e4 | 2467 | rq->bio = rq->biotail = bio; |
1da177e4 | 2468 | |
66846572 N |
2469 | if (bio->bi_bdev) |
2470 | rq->rq_disk = bio->bi_bdev->bd_disk; | |
2471 | } | |
1da177e4 | 2472 | |
2d4dc890 IL |
2473 | #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE |
2474 | /** | |
2475 | * rq_flush_dcache_pages - Helper function to flush all pages in a request | |
2476 | * @rq: the request to be flushed | |
2477 | * | |
2478 | * Description: | |
2479 | * Flush all pages in @rq. | |
2480 | */ | |
2481 | void rq_flush_dcache_pages(struct request *rq) | |
2482 | { | |
2483 | struct req_iterator iter; | |
2484 | struct bio_vec *bvec; | |
2485 | ||
2486 | rq_for_each_segment(bvec, rq, iter) | |
2487 | flush_dcache_page(bvec->bv_page); | |
2488 | } | |
2489 | EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); | |
2490 | #endif | |
2491 | ||
ef9e3fac KU |
2492 | /** |
2493 | * blk_lld_busy - Check if underlying low-level drivers of a device are busy | |
2494 | * @q : the queue of the device being checked | |
2495 | * | |
2496 | * Description: | |
2497 | * Check if underlying low-level drivers of a device are busy. | |
2498 | * If the drivers want to export their busy state, they must set own | |
2499 | * exporting function using blk_queue_lld_busy() first. | |
2500 | * | |
2501 | * Basically, this function is used only by request stacking drivers | |
2502 | * to stop dispatching requests to underlying devices when underlying | |
2503 | * devices are busy. This behavior helps more I/O merging on the queue | |
2504 | * of the request stacking driver and prevents I/O throughput regression | |
2505 | * on burst I/O load. | |
2506 | * | |
2507 | * Return: | |
2508 | * 0 - Not busy (The request stacking driver should dispatch request) | |
2509 | * 1 - Busy (The request stacking driver should stop dispatching request) | |
2510 | */ | |
2511 | int blk_lld_busy(struct request_queue *q) | |
2512 | { | |
2513 | if (q->lld_busy_fn) | |
2514 | return q->lld_busy_fn(q); | |
2515 | ||
2516 | return 0; | |
2517 | } | |
2518 | EXPORT_SYMBOL_GPL(blk_lld_busy); | |
2519 | ||
b0fd271d KU |
2520 | /** |
2521 | * blk_rq_unprep_clone - Helper function to free all bios in a cloned request | |
2522 | * @rq: the clone request to be cleaned up | |
2523 | * | |
2524 | * Description: | |
2525 | * Free all bios in @rq for a cloned request. | |
2526 | */ | |
2527 | void blk_rq_unprep_clone(struct request *rq) | |
2528 | { | |
2529 | struct bio *bio; | |
2530 | ||
2531 | while ((bio = rq->bio) != NULL) { | |
2532 | rq->bio = bio->bi_next; | |
2533 | ||
2534 | bio_put(bio); | |
2535 | } | |
2536 | } | |
2537 | EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); | |
2538 | ||
2539 | /* | |
2540 | * Copy attributes of the original request to the clone request. | |
2541 | * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied. | |
2542 | */ | |
2543 | static void __blk_rq_prep_clone(struct request *dst, struct request *src) | |
2544 | { | |
2545 | dst->cpu = src->cpu; | |
3a2edd0d | 2546 | dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE; |
b0fd271d KU |
2547 | dst->cmd_type = src->cmd_type; |
2548 | dst->__sector = blk_rq_pos(src); | |
2549 | dst->__data_len = blk_rq_bytes(src); | |
2550 | dst->nr_phys_segments = src->nr_phys_segments; | |
2551 | dst->ioprio = src->ioprio; | |
2552 | dst->extra_len = src->extra_len; | |
2553 | } | |
2554 | ||
2555 | /** | |
2556 | * blk_rq_prep_clone - Helper function to setup clone request | |
2557 | * @rq: the request to be setup | |
2558 | * @rq_src: original request to be cloned | |
2559 | * @bs: bio_set that bios for clone are allocated from | |
2560 | * @gfp_mask: memory allocation mask for bio | |
2561 | * @bio_ctr: setup function to be called for each clone bio. | |
2562 | * Returns %0 for success, non %0 for failure. | |
2563 | * @data: private data to be passed to @bio_ctr | |
2564 | * | |
2565 | * Description: | |
2566 | * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. | |
2567 | * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense) | |
2568 | * are not copied, and copying such parts is the caller's responsibility. | |
2569 | * Also, pages which the original bios are pointing to are not copied | |
2570 | * and the cloned bios just point same pages. | |
2571 | * So cloned bios must be completed before original bios, which means | |
2572 | * the caller must complete @rq before @rq_src. | |
2573 | */ | |
2574 | int blk_rq_prep_clone(struct request *rq, struct request *rq_src, | |
2575 | struct bio_set *bs, gfp_t gfp_mask, | |
2576 | int (*bio_ctr)(struct bio *, struct bio *, void *), | |
2577 | void *data) | |
2578 | { | |
2579 | struct bio *bio, *bio_src; | |
2580 | ||
2581 | if (!bs) | |
2582 | bs = fs_bio_set; | |
2583 | ||
2584 | blk_rq_init(NULL, rq); | |
2585 | ||
2586 | __rq_for_each_bio(bio_src, rq_src) { | |
2587 | bio = bio_alloc_bioset(gfp_mask, bio_src->bi_max_vecs, bs); | |
2588 | if (!bio) | |
2589 | goto free_and_out; | |
2590 | ||
2591 | __bio_clone(bio, bio_src); | |
2592 | ||
2593 | if (bio_integrity(bio_src) && | |
7878cba9 | 2594 | bio_integrity_clone(bio, bio_src, gfp_mask, bs)) |
b0fd271d KU |
2595 | goto free_and_out; |
2596 | ||
2597 | if (bio_ctr && bio_ctr(bio, bio_src, data)) | |
2598 | goto free_and_out; | |
2599 | ||
2600 | if (rq->bio) { | |
2601 | rq->biotail->bi_next = bio; | |
2602 | rq->biotail = bio; | |
2603 | } else | |
2604 | rq->bio = rq->biotail = bio; | |
2605 | } | |
2606 | ||
2607 | __blk_rq_prep_clone(rq, rq_src); | |
2608 | ||
2609 | return 0; | |
2610 | ||
2611 | free_and_out: | |
2612 | if (bio) | |
2613 | bio_free(bio, bs); | |
2614 | blk_rq_unprep_clone(rq); | |
2615 | ||
2616 | return -ENOMEM; | |
2617 | } | |
2618 | EXPORT_SYMBOL_GPL(blk_rq_prep_clone); | |
2619 | ||
18887ad9 | 2620 | int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) |
1da177e4 LT |
2621 | { |
2622 | return queue_work(kblockd_workqueue, work); | |
2623 | } | |
1da177e4 LT |
2624 | EXPORT_SYMBOL(kblockd_schedule_work); |
2625 | ||
e43473b7 VG |
2626 | int kblockd_schedule_delayed_work(struct request_queue *q, |
2627 | struct delayed_work *dwork, unsigned long delay) | |
2628 | { | |
2629 | return queue_delayed_work(kblockd_workqueue, dwork, delay); | |
2630 | } | |
2631 | EXPORT_SYMBOL(kblockd_schedule_delayed_work); | |
2632 | ||
73c10101 JA |
2633 | #define PLUG_MAGIC 0x91827364 |
2634 | ||
2635 | void blk_start_plug(struct blk_plug *plug) | |
2636 | { | |
2637 | struct task_struct *tsk = current; | |
2638 | ||
2639 | plug->magic = PLUG_MAGIC; | |
2640 | INIT_LIST_HEAD(&plug->list); | |
2641 | plug->should_sort = 0; | |
2642 | ||
2643 | /* | |
2644 | * If this is a nested plug, don't actually assign it. It will be | |
2645 | * flushed on its own. | |
2646 | */ | |
2647 | if (!tsk->plug) { | |
2648 | /* | |
2649 | * Store ordering should not be needed here, since a potential | |
2650 | * preempt will imply a full memory barrier | |
2651 | */ | |
2652 | tsk->plug = plug; | |
2653 | } | |
2654 | } | |
2655 | EXPORT_SYMBOL(blk_start_plug); | |
2656 | ||
2657 | static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b) | |
2658 | { | |
2659 | struct request *rqa = container_of(a, struct request, queuelist); | |
2660 | struct request *rqb = container_of(b, struct request, queuelist); | |
2661 | ||
f83e8261 | 2662 | return !(rqa->q <= rqb->q); |
73c10101 JA |
2663 | } |
2664 | ||
94b5eb28 JA |
2665 | static void queue_unplugged(struct request_queue *q, unsigned int depth) |
2666 | { | |
2667 | trace_block_unplug_io(q, depth); | |
2668 | __blk_run_queue(q, false); | |
f7566457 JA |
2669 | |
2670 | if (q->unplugged_fn) | |
2671 | q->unplugged_fn(q); | |
94b5eb28 JA |
2672 | } |
2673 | ||
73c10101 JA |
2674 | static void flush_plug_list(struct blk_plug *plug) |
2675 | { | |
2676 | struct request_queue *q; | |
2677 | unsigned long flags; | |
2678 | struct request *rq; | |
109b8129 | 2679 | LIST_HEAD(list); |
94b5eb28 | 2680 | unsigned int depth; |
73c10101 JA |
2681 | |
2682 | BUG_ON(plug->magic != PLUG_MAGIC); | |
2683 | ||
2684 | if (list_empty(&plug->list)) | |
2685 | return; | |
2686 | ||
109b8129 N |
2687 | list_splice_init(&plug->list, &list); |
2688 | ||
2689 | if (plug->should_sort) { | |
2690 | list_sort(NULL, &list, plug_rq_cmp); | |
2691 | plug->should_sort = 0; | |
2692 | } | |
73c10101 JA |
2693 | |
2694 | q = NULL; | |
94b5eb28 | 2695 | depth = 0; |
18811272 JA |
2696 | |
2697 | /* | |
2698 | * Save and disable interrupts here, to avoid doing it for every | |
2699 | * queue lock we have to take. | |
2700 | */ | |
73c10101 | 2701 | local_irq_save(flags); |
109b8129 N |
2702 | while (!list_empty(&list)) { |
2703 | rq = list_entry_rq(list.next); | |
73c10101 JA |
2704 | list_del_init(&rq->queuelist); |
2705 | BUG_ON(!(rq->cmd_flags & REQ_ON_PLUG)); | |
2706 | BUG_ON(!rq->q); | |
2707 | if (rq->q != q) { | |
2708 | if (q) { | |
94b5eb28 | 2709 | queue_unplugged(q, depth); |
73c10101 JA |
2710 | spin_unlock(q->queue_lock); |
2711 | } | |
2712 | q = rq->q; | |
94b5eb28 | 2713 | depth = 0; |
73c10101 JA |
2714 | spin_lock(q->queue_lock); |
2715 | } | |
2716 | rq->cmd_flags &= ~REQ_ON_PLUG; | |
2717 | ||
2718 | /* | |
2719 | * rq is already accounted, so use raw insert | |
2720 | */ | |
401a18e9 JA |
2721 | if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) |
2722 | __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH); | |
2723 | else | |
2724 | __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE); | |
94b5eb28 JA |
2725 | |
2726 | depth++; | |
73c10101 JA |
2727 | } |
2728 | ||
2729 | if (q) { | |
94b5eb28 | 2730 | queue_unplugged(q, depth); |
73c10101 JA |
2731 | spin_unlock(q->queue_lock); |
2732 | } | |
2733 | ||
73c10101 JA |
2734 | local_irq_restore(flags); |
2735 | } | |
2736 | ||
2737 | static void __blk_finish_plug(struct task_struct *tsk, struct blk_plug *plug) | |
2738 | { | |
2739 | flush_plug_list(plug); | |
2740 | ||
2741 | if (plug == tsk->plug) | |
2742 | tsk->plug = NULL; | |
2743 | } | |
2744 | ||
2745 | void blk_finish_plug(struct blk_plug *plug) | |
2746 | { | |
2747 | if (plug) | |
2748 | __blk_finish_plug(current, plug); | |
2749 | } | |
2750 | EXPORT_SYMBOL(blk_finish_plug); | |
2751 | ||
2752 | void __blk_flush_plug(struct task_struct *tsk, struct blk_plug *plug) | |
2753 | { | |
2754 | __blk_finish_plug(tsk, plug); | |
2755 | tsk->plug = plug; | |
2756 | } | |
2757 | EXPORT_SYMBOL(__blk_flush_plug); | |
2758 | ||
1da177e4 LT |
2759 | int __init blk_dev_init(void) |
2760 | { | |
9eb55b03 NK |
2761 | BUILD_BUG_ON(__REQ_NR_BITS > 8 * |
2762 | sizeof(((struct request *)0)->cmd_flags)); | |
2763 | ||
89b90be2 TH |
2764 | /* used for unplugging and affects IO latency/throughput - HIGHPRI */ |
2765 | kblockd_workqueue = alloc_workqueue("kblockd", | |
2766 | WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); | |
1da177e4 LT |
2767 | if (!kblockd_workqueue) |
2768 | panic("Failed to create kblockd\n"); | |
2769 | ||
2770 | request_cachep = kmem_cache_create("blkdev_requests", | |
20c2df83 | 2771 | sizeof(struct request), 0, SLAB_PANIC, NULL); |
1da177e4 | 2772 | |
8324aa91 | 2773 | blk_requestq_cachep = kmem_cache_create("blkdev_queue", |
165125e1 | 2774 | sizeof(struct request_queue), 0, SLAB_PANIC, NULL); |
1da177e4 | 2775 | |
d38ecf93 | 2776 | return 0; |
1da177e4 | 2777 | } |