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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> | |
6 | * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> - July2000 | |
7 | * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 | |
8 | */ | |
9 | ||
10 | /* | |
11 | * This handles all read/write requests to block devices | |
12 | */ | |
1da177e4 LT |
13 | #include <linux/kernel.h> |
14 | #include <linux/module.h> | |
15 | #include <linux/backing-dev.h> | |
16 | #include <linux/bio.h> | |
17 | #include <linux/blkdev.h> | |
18 | #include <linux/highmem.h> | |
19 | #include <linux/mm.h> | |
20 | #include <linux/kernel_stat.h> | |
21 | #include <linux/string.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/bootmem.h> /* for max_pfn/max_low_pfn */ | |
24 | #include <linux/completion.h> | |
25 | #include <linux/slab.h> | |
26 | #include <linux/swap.h> | |
27 | #include <linux/writeback.h> | |
ff856bad JA |
28 | #include <linux/interrupt.h> |
29 | #include <linux/cpu.h> | |
2056a782 | 30 | #include <linux/blktrace_api.h> |
1da177e4 LT |
31 | |
32 | /* | |
33 | * for max sense size | |
34 | */ | |
35 | #include <scsi/scsi_cmnd.h> | |
36 | ||
37 | static void blk_unplug_work(void *data); | |
38 | static void blk_unplug_timeout(unsigned long data); | |
93d17d3d | 39 | static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io); |
52d9e675 TH |
40 | static void init_request_from_bio(struct request *req, struct bio *bio); |
41 | static int __make_request(request_queue_t *q, struct bio *bio); | |
1da177e4 LT |
42 | |
43 | /* | |
44 | * For the allocated request tables | |
45 | */ | |
46 | static kmem_cache_t *request_cachep; | |
47 | ||
48 | /* | |
49 | * For queue allocation | |
50 | */ | |
51 | static kmem_cache_t *requestq_cachep; | |
52 | ||
53 | /* | |
54 | * For io context allocations | |
55 | */ | |
56 | static kmem_cache_t *iocontext_cachep; | |
57 | ||
58 | static wait_queue_head_t congestion_wqh[2] = { | |
59 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
60 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
61 | }; | |
62 | ||
63 | /* | |
64 | * Controlling structure to kblockd | |
65 | */ | |
ff856bad | 66 | static struct workqueue_struct *kblockd_workqueue; |
1da177e4 LT |
67 | |
68 | unsigned long blk_max_low_pfn, blk_max_pfn; | |
69 | ||
70 | EXPORT_SYMBOL(blk_max_low_pfn); | |
71 | EXPORT_SYMBOL(blk_max_pfn); | |
72 | ||
ff856bad JA |
73 | static DEFINE_PER_CPU(struct list_head, blk_cpu_done); |
74 | ||
1da177e4 LT |
75 | /* Amount of time in which a process may batch requests */ |
76 | #define BLK_BATCH_TIME (HZ/50UL) | |
77 | ||
78 | /* Number of requests a "batching" process may submit */ | |
79 | #define BLK_BATCH_REQ 32 | |
80 | ||
81 | /* | |
82 | * Return the threshold (number of used requests) at which the queue is | |
83 | * considered to be congested. It include a little hysteresis to keep the | |
84 | * context switch rate down. | |
85 | */ | |
86 | static inline int queue_congestion_on_threshold(struct request_queue *q) | |
87 | { | |
88 | return q->nr_congestion_on; | |
89 | } | |
90 | ||
91 | /* | |
92 | * The threshold at which a queue is considered to be uncongested | |
93 | */ | |
94 | static inline int queue_congestion_off_threshold(struct request_queue *q) | |
95 | { | |
96 | return q->nr_congestion_off; | |
97 | } | |
98 | ||
99 | static void blk_queue_congestion_threshold(struct request_queue *q) | |
100 | { | |
101 | int nr; | |
102 | ||
103 | nr = q->nr_requests - (q->nr_requests / 8) + 1; | |
104 | if (nr > q->nr_requests) | |
105 | nr = q->nr_requests; | |
106 | q->nr_congestion_on = nr; | |
107 | ||
108 | nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; | |
109 | if (nr < 1) | |
110 | nr = 1; | |
111 | q->nr_congestion_off = nr; | |
112 | } | |
113 | ||
114 | /* | |
115 | * A queue has just exitted congestion. Note this in the global counter of | |
116 | * congested queues, and wake up anyone who was waiting for requests to be | |
117 | * put back. | |
118 | */ | |
119 | static void clear_queue_congested(request_queue_t *q, int rw) | |
120 | { | |
121 | enum bdi_state bit; | |
122 | wait_queue_head_t *wqh = &congestion_wqh[rw]; | |
123 | ||
124 | bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; | |
125 | clear_bit(bit, &q->backing_dev_info.state); | |
126 | smp_mb__after_clear_bit(); | |
127 | if (waitqueue_active(wqh)) | |
128 | wake_up(wqh); | |
129 | } | |
130 | ||
131 | /* | |
132 | * A queue has just entered congestion. Flag that in the queue's VM-visible | |
133 | * state flags and increment the global gounter of congested queues. | |
134 | */ | |
135 | static void set_queue_congested(request_queue_t *q, int rw) | |
136 | { | |
137 | enum bdi_state bit; | |
138 | ||
139 | bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; | |
140 | set_bit(bit, &q->backing_dev_info.state); | |
141 | } | |
142 | ||
143 | /** | |
144 | * blk_get_backing_dev_info - get the address of a queue's backing_dev_info | |
145 | * @bdev: device | |
146 | * | |
147 | * Locates the passed device's request queue and returns the address of its | |
148 | * backing_dev_info | |
149 | * | |
150 | * Will return NULL if the request queue cannot be located. | |
151 | */ | |
152 | struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) | |
153 | { | |
154 | struct backing_dev_info *ret = NULL; | |
155 | request_queue_t *q = bdev_get_queue(bdev); | |
156 | ||
157 | if (q) | |
158 | ret = &q->backing_dev_info; | |
159 | return ret; | |
160 | } | |
161 | ||
162 | EXPORT_SYMBOL(blk_get_backing_dev_info); | |
163 | ||
164 | void blk_queue_activity_fn(request_queue_t *q, activity_fn *fn, void *data) | |
165 | { | |
166 | q->activity_fn = fn; | |
167 | q->activity_data = data; | |
168 | } | |
169 | ||
170 | EXPORT_SYMBOL(blk_queue_activity_fn); | |
171 | ||
172 | /** | |
173 | * blk_queue_prep_rq - set a prepare_request function for queue | |
174 | * @q: queue | |
175 | * @pfn: prepare_request function | |
176 | * | |
177 | * It's possible for a queue to register a prepare_request callback which | |
178 | * is invoked before the request is handed to the request_fn. The goal of | |
179 | * the function is to prepare a request for I/O, it can be used to build a | |
180 | * cdb from the request data for instance. | |
181 | * | |
182 | */ | |
183 | void blk_queue_prep_rq(request_queue_t *q, prep_rq_fn *pfn) | |
184 | { | |
185 | q->prep_rq_fn = pfn; | |
186 | } | |
187 | ||
188 | EXPORT_SYMBOL(blk_queue_prep_rq); | |
189 | ||
190 | /** | |
191 | * blk_queue_merge_bvec - set a merge_bvec function for queue | |
192 | * @q: queue | |
193 | * @mbfn: merge_bvec_fn | |
194 | * | |
195 | * Usually queues have static limitations on the max sectors or segments that | |
196 | * we can put in a request. Stacking drivers may have some settings that | |
197 | * are dynamic, and thus we have to query the queue whether it is ok to | |
198 | * add a new bio_vec to a bio at a given offset or not. If the block device | |
199 | * has such limitations, it needs to register a merge_bvec_fn to control | |
200 | * the size of bio's sent to it. Note that a block device *must* allow a | |
201 | * single page to be added to an empty bio. The block device driver may want | |
202 | * to use the bio_split() function to deal with these bio's. By default | |
203 | * no merge_bvec_fn is defined for a queue, and only the fixed limits are | |
204 | * honored. | |
205 | */ | |
206 | void blk_queue_merge_bvec(request_queue_t *q, merge_bvec_fn *mbfn) | |
207 | { | |
208 | q->merge_bvec_fn = mbfn; | |
209 | } | |
210 | ||
211 | EXPORT_SYMBOL(blk_queue_merge_bvec); | |
212 | ||
ff856bad JA |
213 | void blk_queue_softirq_done(request_queue_t *q, softirq_done_fn *fn) |
214 | { | |
215 | q->softirq_done_fn = fn; | |
216 | } | |
217 | ||
218 | EXPORT_SYMBOL(blk_queue_softirq_done); | |
219 | ||
1da177e4 LT |
220 | /** |
221 | * blk_queue_make_request - define an alternate make_request function for a device | |
222 | * @q: the request queue for the device to be affected | |
223 | * @mfn: the alternate make_request function | |
224 | * | |
225 | * Description: | |
226 | * The normal way for &struct bios to be passed to a device | |
227 | * driver is for them to be collected into requests on a request | |
228 | * queue, and then to allow the device driver to select requests | |
229 | * off that queue when it is ready. This works well for many block | |
230 | * devices. However some block devices (typically virtual devices | |
231 | * such as md or lvm) do not benefit from the processing on the | |
232 | * request queue, and are served best by having the requests passed | |
233 | * directly to them. This can be achieved by providing a function | |
234 | * to blk_queue_make_request(). | |
235 | * | |
236 | * Caveat: | |
237 | * The driver that does this *must* be able to deal appropriately | |
238 | * with buffers in "highmemory". This can be accomplished by either calling | |
239 | * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling | |
240 | * blk_queue_bounce() to create a buffer in normal memory. | |
241 | **/ | |
242 | void blk_queue_make_request(request_queue_t * q, make_request_fn * mfn) | |
243 | { | |
244 | /* | |
245 | * set defaults | |
246 | */ | |
247 | q->nr_requests = BLKDEV_MAX_RQ; | |
309c0a1d SM |
248 | blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); |
249 | blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); | |
1da177e4 LT |
250 | q->make_request_fn = mfn; |
251 | q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; | |
252 | q->backing_dev_info.state = 0; | |
253 | q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; | |
defd94b7 | 254 | blk_queue_max_sectors(q, SAFE_MAX_SECTORS); |
1da177e4 LT |
255 | blk_queue_hardsect_size(q, 512); |
256 | blk_queue_dma_alignment(q, 511); | |
257 | blk_queue_congestion_threshold(q); | |
258 | q->nr_batching = BLK_BATCH_REQ; | |
259 | ||
260 | q->unplug_thresh = 4; /* hmm */ | |
261 | q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */ | |
262 | if (q->unplug_delay == 0) | |
263 | q->unplug_delay = 1; | |
264 | ||
265 | INIT_WORK(&q->unplug_work, blk_unplug_work, q); | |
266 | ||
267 | q->unplug_timer.function = blk_unplug_timeout; | |
268 | q->unplug_timer.data = (unsigned long)q; | |
269 | ||
270 | /* | |
271 | * by default assume old behaviour and bounce for any highmem page | |
272 | */ | |
273 | blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); | |
274 | ||
275 | blk_queue_activity_fn(q, NULL, NULL); | |
1da177e4 LT |
276 | } |
277 | ||
278 | EXPORT_SYMBOL(blk_queue_make_request); | |
279 | ||
280 | static inline void rq_init(request_queue_t *q, struct request *rq) | |
281 | { | |
282 | INIT_LIST_HEAD(&rq->queuelist); | |
ff856bad | 283 | INIT_LIST_HEAD(&rq->donelist); |
9817064b | 284 | INIT_HLIST_NODE(&rq->hash); |
1da177e4 LT |
285 | |
286 | rq->errors = 0; | |
287 | rq->rq_status = RQ_ACTIVE; | |
288 | rq->bio = rq->biotail = NULL; | |
22e2c507 | 289 | rq->ioprio = 0; |
1da177e4 LT |
290 | rq->buffer = NULL; |
291 | rq->ref_count = 1; | |
292 | rq->q = q; | |
293 | rq->waiting = NULL; | |
294 | rq->special = NULL; | |
295 | rq->data_len = 0; | |
296 | rq->data = NULL; | |
df46b9a4 | 297 | rq->nr_phys_segments = 0; |
1da177e4 LT |
298 | rq->sense = NULL; |
299 | rq->end_io = NULL; | |
300 | rq->end_io_data = NULL; | |
ff856bad | 301 | rq->completion_data = NULL; |
1da177e4 LT |
302 | } |
303 | ||
304 | /** | |
305 | * blk_queue_ordered - does this queue support ordered writes | |
797e7dbb TH |
306 | * @q: the request queue |
307 | * @ordered: one of QUEUE_ORDERED_* | |
fddfdeaf | 308 | * @prepare_flush_fn: rq setup helper for cache flush ordered writes |
1da177e4 LT |
309 | * |
310 | * Description: | |
311 | * For journalled file systems, doing ordered writes on a commit | |
312 | * block instead of explicitly doing wait_on_buffer (which is bad | |
313 | * for performance) can be a big win. Block drivers supporting this | |
314 | * feature should call this function and indicate so. | |
315 | * | |
316 | **/ | |
797e7dbb TH |
317 | int blk_queue_ordered(request_queue_t *q, unsigned ordered, |
318 | prepare_flush_fn *prepare_flush_fn) | |
319 | { | |
320 | if (ordered & (QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH) && | |
321 | prepare_flush_fn == NULL) { | |
322 | printk(KERN_ERR "blk_queue_ordered: prepare_flush_fn required\n"); | |
323 | return -EINVAL; | |
324 | } | |
325 | ||
326 | if (ordered != QUEUE_ORDERED_NONE && | |
327 | ordered != QUEUE_ORDERED_DRAIN && | |
328 | ordered != QUEUE_ORDERED_DRAIN_FLUSH && | |
329 | ordered != QUEUE_ORDERED_DRAIN_FUA && | |
330 | ordered != QUEUE_ORDERED_TAG && | |
331 | ordered != QUEUE_ORDERED_TAG_FLUSH && | |
332 | ordered != QUEUE_ORDERED_TAG_FUA) { | |
333 | printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered); | |
334 | return -EINVAL; | |
1da177e4 | 335 | } |
797e7dbb | 336 | |
60481b12 | 337 | q->ordered = ordered; |
797e7dbb TH |
338 | q->next_ordered = ordered; |
339 | q->prepare_flush_fn = prepare_flush_fn; | |
340 | ||
341 | return 0; | |
1da177e4 LT |
342 | } |
343 | ||
344 | EXPORT_SYMBOL(blk_queue_ordered); | |
345 | ||
346 | /** | |
347 | * blk_queue_issue_flush_fn - set function for issuing a flush | |
348 | * @q: the request queue | |
349 | * @iff: the function to be called issuing the flush | |
350 | * | |
351 | * Description: | |
352 | * If a driver supports issuing a flush command, the support is notified | |
353 | * to the block layer by defining it through this call. | |
354 | * | |
355 | **/ | |
356 | void blk_queue_issue_flush_fn(request_queue_t *q, issue_flush_fn *iff) | |
357 | { | |
358 | q->issue_flush_fn = iff; | |
359 | } | |
360 | ||
361 | EXPORT_SYMBOL(blk_queue_issue_flush_fn); | |
362 | ||
363 | /* | |
364 | * Cache flushing for ordered writes handling | |
365 | */ | |
797e7dbb | 366 | inline unsigned blk_ordered_cur_seq(request_queue_t *q) |
1da177e4 | 367 | { |
797e7dbb TH |
368 | if (!q->ordseq) |
369 | return 0; | |
370 | return 1 << ffz(q->ordseq); | |
1da177e4 LT |
371 | } |
372 | ||
797e7dbb | 373 | unsigned blk_ordered_req_seq(struct request *rq) |
1da177e4 | 374 | { |
1da177e4 LT |
375 | request_queue_t *q = rq->q; |
376 | ||
797e7dbb | 377 | BUG_ON(q->ordseq == 0); |
8922e16c | 378 | |
797e7dbb TH |
379 | if (rq == &q->pre_flush_rq) |
380 | return QUEUE_ORDSEQ_PREFLUSH; | |
381 | if (rq == &q->bar_rq) | |
382 | return QUEUE_ORDSEQ_BAR; | |
383 | if (rq == &q->post_flush_rq) | |
384 | return QUEUE_ORDSEQ_POSTFLUSH; | |
1da177e4 | 385 | |
4aff5e23 JA |
386 | if ((rq->cmd_flags & REQ_ORDERED_COLOR) == |
387 | (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR)) | |
797e7dbb TH |
388 | return QUEUE_ORDSEQ_DRAIN; |
389 | else | |
390 | return QUEUE_ORDSEQ_DONE; | |
1da177e4 LT |
391 | } |
392 | ||
797e7dbb | 393 | void blk_ordered_complete_seq(request_queue_t *q, unsigned seq, int error) |
1da177e4 | 394 | { |
797e7dbb TH |
395 | struct request *rq; |
396 | int uptodate; | |
1da177e4 | 397 | |
797e7dbb TH |
398 | if (error && !q->orderr) |
399 | q->orderr = error; | |
1da177e4 | 400 | |
797e7dbb TH |
401 | BUG_ON(q->ordseq & seq); |
402 | q->ordseq |= seq; | |
1da177e4 | 403 | |
797e7dbb TH |
404 | if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE) |
405 | return; | |
1da177e4 LT |
406 | |
407 | /* | |
797e7dbb | 408 | * Okay, sequence complete. |
1da177e4 | 409 | */ |
797e7dbb TH |
410 | rq = q->orig_bar_rq; |
411 | uptodate = q->orderr ? q->orderr : 1; | |
1da177e4 | 412 | |
797e7dbb | 413 | q->ordseq = 0; |
1da177e4 | 414 | |
797e7dbb TH |
415 | end_that_request_first(rq, uptodate, rq->hard_nr_sectors); |
416 | end_that_request_last(rq, uptodate); | |
1da177e4 LT |
417 | } |
418 | ||
797e7dbb | 419 | static void pre_flush_end_io(struct request *rq, int error) |
1da177e4 | 420 | { |
797e7dbb TH |
421 | elv_completed_request(rq->q, rq); |
422 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error); | |
423 | } | |
1da177e4 | 424 | |
797e7dbb TH |
425 | static void bar_end_io(struct request *rq, int error) |
426 | { | |
427 | elv_completed_request(rq->q, rq); | |
428 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error); | |
429 | } | |
1da177e4 | 430 | |
797e7dbb TH |
431 | static void post_flush_end_io(struct request *rq, int error) |
432 | { | |
433 | elv_completed_request(rq->q, rq); | |
434 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error); | |
435 | } | |
1da177e4 | 436 | |
797e7dbb TH |
437 | static void queue_flush(request_queue_t *q, unsigned which) |
438 | { | |
439 | struct request *rq; | |
440 | rq_end_io_fn *end_io; | |
1da177e4 | 441 | |
797e7dbb TH |
442 | if (which == QUEUE_ORDERED_PREFLUSH) { |
443 | rq = &q->pre_flush_rq; | |
444 | end_io = pre_flush_end_io; | |
445 | } else { | |
446 | rq = &q->post_flush_rq; | |
447 | end_io = post_flush_end_io; | |
1da177e4 | 448 | } |
797e7dbb | 449 | |
4aff5e23 | 450 | rq->cmd_flags = REQ_HARDBARRIER; |
797e7dbb | 451 | rq_init(q, rq); |
797e7dbb TH |
452 | rq->elevator_private = NULL; |
453 | rq->rq_disk = q->bar_rq.rq_disk; | |
454 | rq->rl = NULL; | |
455 | rq->end_io = end_io; | |
456 | q->prepare_flush_fn(q, rq); | |
457 | ||
30e9656c | 458 | elv_insert(q, rq, ELEVATOR_INSERT_FRONT); |
1da177e4 LT |
459 | } |
460 | ||
797e7dbb TH |
461 | static inline struct request *start_ordered(request_queue_t *q, |
462 | struct request *rq) | |
1da177e4 | 463 | { |
797e7dbb TH |
464 | q->bi_size = 0; |
465 | q->orderr = 0; | |
466 | q->ordered = q->next_ordered; | |
467 | q->ordseq |= QUEUE_ORDSEQ_STARTED; | |
468 | ||
469 | /* | |
470 | * Prep proxy barrier request. | |
471 | */ | |
472 | blkdev_dequeue_request(rq); | |
473 | q->orig_bar_rq = rq; | |
474 | rq = &q->bar_rq; | |
4aff5e23 | 475 | rq->cmd_flags = 0; |
797e7dbb | 476 | rq_init(q, rq); |
4aff5e23 JA |
477 | if (bio_data_dir(q->orig_bar_rq->bio) == WRITE) |
478 | rq->cmd_flags |= REQ_RW; | |
479 | rq->cmd_flags |= q->ordered & QUEUE_ORDERED_FUA ? REQ_FUA : 0; | |
797e7dbb TH |
480 | rq->elevator_private = NULL; |
481 | rq->rl = NULL; | |
482 | init_request_from_bio(rq, q->orig_bar_rq->bio); | |
483 | rq->end_io = bar_end_io; | |
484 | ||
485 | /* | |
486 | * Queue ordered sequence. As we stack them at the head, we | |
487 | * need to queue in reverse order. Note that we rely on that | |
488 | * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs | |
489 | * request gets inbetween ordered sequence. | |
490 | */ | |
491 | if (q->ordered & QUEUE_ORDERED_POSTFLUSH) | |
492 | queue_flush(q, QUEUE_ORDERED_POSTFLUSH); | |
493 | else | |
494 | q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH; | |
495 | ||
30e9656c | 496 | elv_insert(q, rq, ELEVATOR_INSERT_FRONT); |
797e7dbb TH |
497 | |
498 | if (q->ordered & QUEUE_ORDERED_PREFLUSH) { | |
499 | queue_flush(q, QUEUE_ORDERED_PREFLUSH); | |
500 | rq = &q->pre_flush_rq; | |
501 | } else | |
502 | q->ordseq |= QUEUE_ORDSEQ_PREFLUSH; | |
1da177e4 | 503 | |
797e7dbb TH |
504 | if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0) |
505 | q->ordseq |= QUEUE_ORDSEQ_DRAIN; | |
506 | else | |
507 | rq = NULL; | |
508 | ||
509 | return rq; | |
1da177e4 LT |
510 | } |
511 | ||
797e7dbb | 512 | int blk_do_ordered(request_queue_t *q, struct request **rqp) |
1da177e4 | 513 | { |
9a7a67af | 514 | struct request *rq = *rqp; |
797e7dbb | 515 | int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq); |
1da177e4 | 516 | |
797e7dbb TH |
517 | if (!q->ordseq) { |
518 | if (!is_barrier) | |
519 | return 1; | |
1da177e4 | 520 | |
797e7dbb TH |
521 | if (q->next_ordered != QUEUE_ORDERED_NONE) { |
522 | *rqp = start_ordered(q, rq); | |
523 | return 1; | |
524 | } else { | |
525 | /* | |
526 | * This can happen when the queue switches to | |
527 | * ORDERED_NONE while this request is on it. | |
528 | */ | |
529 | blkdev_dequeue_request(rq); | |
530 | end_that_request_first(rq, -EOPNOTSUPP, | |
531 | rq->hard_nr_sectors); | |
532 | end_that_request_last(rq, -EOPNOTSUPP); | |
533 | *rqp = NULL; | |
534 | return 0; | |
535 | } | |
536 | } | |
1da177e4 | 537 | |
9a7a67af JA |
538 | /* |
539 | * Ordered sequence in progress | |
540 | */ | |
541 | ||
542 | /* Special requests are not subject to ordering rules. */ | |
543 | if (!blk_fs_request(rq) && | |
544 | rq != &q->pre_flush_rq && rq != &q->post_flush_rq) | |
545 | return 1; | |
546 | ||
797e7dbb | 547 | if (q->ordered & QUEUE_ORDERED_TAG) { |
9a7a67af | 548 | /* Ordered by tag. Blocking the next barrier is enough. */ |
797e7dbb TH |
549 | if (is_barrier && rq != &q->bar_rq) |
550 | *rqp = NULL; | |
9a7a67af JA |
551 | } else { |
552 | /* Ordered by draining. Wait for turn. */ | |
553 | WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q)); | |
554 | if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q)) | |
555 | *rqp = NULL; | |
1da177e4 LT |
556 | } |
557 | ||
558 | return 1; | |
559 | } | |
560 | ||
797e7dbb | 561 | static int flush_dry_bio_endio(struct bio *bio, unsigned int bytes, int error) |
1da177e4 | 562 | { |
797e7dbb TH |
563 | request_queue_t *q = bio->bi_private; |
564 | struct bio_vec *bvec; | |
565 | int i; | |
566 | ||
567 | /* | |
568 | * This is dry run, restore bio_sector and size. We'll finish | |
569 | * this request again with the original bi_end_io after an | |
570 | * error occurs or post flush is complete. | |
571 | */ | |
572 | q->bi_size += bytes; | |
573 | ||
574 | if (bio->bi_size) | |
575 | return 1; | |
576 | ||
577 | /* Rewind bvec's */ | |
578 | bio->bi_idx = 0; | |
579 | bio_for_each_segment(bvec, bio, i) { | |
580 | bvec->bv_len += bvec->bv_offset; | |
581 | bvec->bv_offset = 0; | |
582 | } | |
583 | ||
584 | /* Reset bio */ | |
585 | set_bit(BIO_UPTODATE, &bio->bi_flags); | |
586 | bio->bi_size = q->bi_size; | |
587 | bio->bi_sector -= (q->bi_size >> 9); | |
588 | q->bi_size = 0; | |
589 | ||
590 | return 0; | |
1da177e4 | 591 | } |
1da177e4 | 592 | |
797e7dbb TH |
593 | static inline int ordered_bio_endio(struct request *rq, struct bio *bio, |
594 | unsigned int nbytes, int error) | |
1da177e4 | 595 | { |
797e7dbb TH |
596 | request_queue_t *q = rq->q; |
597 | bio_end_io_t *endio; | |
598 | void *private; | |
599 | ||
600 | if (&q->bar_rq != rq) | |
601 | return 0; | |
602 | ||
603 | /* | |
604 | * Okay, this is the barrier request in progress, dry finish it. | |
605 | */ | |
606 | if (error && !q->orderr) | |
607 | q->orderr = error; | |
608 | ||
609 | endio = bio->bi_end_io; | |
610 | private = bio->bi_private; | |
611 | bio->bi_end_io = flush_dry_bio_endio; | |
612 | bio->bi_private = q; | |
613 | ||
614 | bio_endio(bio, nbytes, error); | |
615 | ||
616 | bio->bi_end_io = endio; | |
617 | bio->bi_private = private; | |
618 | ||
619 | return 1; | |
1da177e4 | 620 | } |
1da177e4 LT |
621 | |
622 | /** | |
623 | * blk_queue_bounce_limit - set bounce buffer limit for queue | |
624 | * @q: the request queue for the device | |
625 | * @dma_addr: bus address limit | |
626 | * | |
627 | * Description: | |
628 | * Different hardware can have different requirements as to what pages | |
629 | * it can do I/O directly to. A low level driver can call | |
630 | * blk_queue_bounce_limit to have lower memory pages allocated as bounce | |
5ee1af9f | 631 | * buffers for doing I/O to pages residing above @page. |
1da177e4 LT |
632 | **/ |
633 | void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr) | |
634 | { | |
635 | unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT; | |
5ee1af9f AK |
636 | int dma = 0; |
637 | ||
638 | q->bounce_gfp = GFP_NOIO; | |
639 | #if BITS_PER_LONG == 64 | |
640 | /* Assume anything <= 4GB can be handled by IOMMU. | |
641 | Actually some IOMMUs can handle everything, but I don't | |
642 | know of a way to test this here. */ | |
8269730b | 643 | if (bounce_pfn < (min_t(u64,0xffffffff,BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) |
5ee1af9f AK |
644 | dma = 1; |
645 | q->bounce_pfn = max_low_pfn; | |
646 | #else | |
647 | if (bounce_pfn < blk_max_low_pfn) | |
648 | dma = 1; | |
649 | q->bounce_pfn = bounce_pfn; | |
650 | #endif | |
651 | if (dma) { | |
1da177e4 LT |
652 | init_emergency_isa_pool(); |
653 | q->bounce_gfp = GFP_NOIO | GFP_DMA; | |
5ee1af9f AK |
654 | q->bounce_pfn = bounce_pfn; |
655 | } | |
1da177e4 LT |
656 | } |
657 | ||
658 | EXPORT_SYMBOL(blk_queue_bounce_limit); | |
659 | ||
660 | /** | |
661 | * blk_queue_max_sectors - set max sectors for a request for this queue | |
662 | * @q: the request queue for the device | |
663 | * @max_sectors: max sectors in the usual 512b unit | |
664 | * | |
665 | * Description: | |
666 | * Enables a low level driver to set an upper limit on the size of | |
667 | * received requests. | |
668 | **/ | |
2cb2e147 | 669 | void blk_queue_max_sectors(request_queue_t *q, unsigned int max_sectors) |
1da177e4 LT |
670 | { |
671 | if ((max_sectors << 9) < PAGE_CACHE_SIZE) { | |
672 | max_sectors = 1 << (PAGE_CACHE_SHIFT - 9); | |
673 | printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors); | |
674 | } | |
675 | ||
defd94b7 MC |
676 | if (BLK_DEF_MAX_SECTORS > max_sectors) |
677 | q->max_hw_sectors = q->max_sectors = max_sectors; | |
678 | else { | |
679 | q->max_sectors = BLK_DEF_MAX_SECTORS; | |
680 | q->max_hw_sectors = max_sectors; | |
681 | } | |
1da177e4 LT |
682 | } |
683 | ||
684 | EXPORT_SYMBOL(blk_queue_max_sectors); | |
685 | ||
686 | /** | |
687 | * blk_queue_max_phys_segments - set max phys segments for a request for this queue | |
688 | * @q: the request queue for the device | |
689 | * @max_segments: max number of segments | |
690 | * | |
691 | * Description: | |
692 | * Enables a low level driver to set an upper limit on the number of | |
693 | * physical data segments in a request. This would be the largest sized | |
694 | * scatter list the driver could handle. | |
695 | **/ | |
696 | void blk_queue_max_phys_segments(request_queue_t *q, unsigned short max_segments) | |
697 | { | |
698 | if (!max_segments) { | |
699 | max_segments = 1; | |
700 | printk("%s: set to minimum %d\n", __FUNCTION__, max_segments); | |
701 | } | |
702 | ||
703 | q->max_phys_segments = max_segments; | |
704 | } | |
705 | ||
706 | EXPORT_SYMBOL(blk_queue_max_phys_segments); | |
707 | ||
708 | /** | |
709 | * blk_queue_max_hw_segments - set max hw segments for a request for this queue | |
710 | * @q: the request queue for the device | |
711 | * @max_segments: max number of segments | |
712 | * | |
713 | * Description: | |
714 | * Enables a low level driver to set an upper limit on the number of | |
715 | * hw data segments in a request. This would be the largest number of | |
716 | * address/length pairs the host adapter can actually give as once | |
717 | * to the device. | |
718 | **/ | |
719 | void blk_queue_max_hw_segments(request_queue_t *q, unsigned short max_segments) | |
720 | { | |
721 | if (!max_segments) { | |
722 | max_segments = 1; | |
723 | printk("%s: set to minimum %d\n", __FUNCTION__, max_segments); | |
724 | } | |
725 | ||
726 | q->max_hw_segments = max_segments; | |
727 | } | |
728 | ||
729 | EXPORT_SYMBOL(blk_queue_max_hw_segments); | |
730 | ||
731 | /** | |
732 | * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg | |
733 | * @q: the request queue for the device | |
734 | * @max_size: max size of segment in bytes | |
735 | * | |
736 | * Description: | |
737 | * Enables a low level driver to set an upper limit on the size of a | |
738 | * coalesced segment | |
739 | **/ | |
740 | void blk_queue_max_segment_size(request_queue_t *q, unsigned int max_size) | |
741 | { | |
742 | if (max_size < PAGE_CACHE_SIZE) { | |
743 | max_size = PAGE_CACHE_SIZE; | |
744 | printk("%s: set to minimum %d\n", __FUNCTION__, max_size); | |
745 | } | |
746 | ||
747 | q->max_segment_size = max_size; | |
748 | } | |
749 | ||
750 | EXPORT_SYMBOL(blk_queue_max_segment_size); | |
751 | ||
752 | /** | |
753 | * blk_queue_hardsect_size - set hardware sector size for the queue | |
754 | * @q: the request queue for the device | |
755 | * @size: the hardware sector size, in bytes | |
756 | * | |
757 | * Description: | |
758 | * This should typically be set to the lowest possible sector size | |
759 | * that the hardware can operate on (possible without reverting to | |
760 | * even internal read-modify-write operations). Usually the default | |
761 | * of 512 covers most hardware. | |
762 | **/ | |
763 | void blk_queue_hardsect_size(request_queue_t *q, unsigned short size) | |
764 | { | |
765 | q->hardsect_size = size; | |
766 | } | |
767 | ||
768 | EXPORT_SYMBOL(blk_queue_hardsect_size); | |
769 | ||
770 | /* | |
771 | * Returns the minimum that is _not_ zero, unless both are zero. | |
772 | */ | |
773 | #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) | |
774 | ||
775 | /** | |
776 | * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers | |
777 | * @t: the stacking driver (top) | |
778 | * @b: the underlying device (bottom) | |
779 | **/ | |
780 | void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b) | |
781 | { | |
782 | /* zero is "infinity" */ | |
defd94b7 MC |
783 | t->max_sectors = min_not_zero(t->max_sectors,b->max_sectors); |
784 | t->max_hw_sectors = min_not_zero(t->max_hw_sectors,b->max_hw_sectors); | |
1da177e4 LT |
785 | |
786 | t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments); | |
787 | t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments); | |
788 | t->max_segment_size = min(t->max_segment_size,b->max_segment_size); | |
789 | t->hardsect_size = max(t->hardsect_size,b->hardsect_size); | |
89e5c8b5 N |
790 | if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) |
791 | clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags); | |
1da177e4 LT |
792 | } |
793 | ||
794 | EXPORT_SYMBOL(blk_queue_stack_limits); | |
795 | ||
796 | /** | |
797 | * blk_queue_segment_boundary - set boundary rules for segment merging | |
798 | * @q: the request queue for the device | |
799 | * @mask: the memory boundary mask | |
800 | **/ | |
801 | void blk_queue_segment_boundary(request_queue_t *q, unsigned long mask) | |
802 | { | |
803 | if (mask < PAGE_CACHE_SIZE - 1) { | |
804 | mask = PAGE_CACHE_SIZE - 1; | |
805 | printk("%s: set to minimum %lx\n", __FUNCTION__, mask); | |
806 | } | |
807 | ||
808 | q->seg_boundary_mask = mask; | |
809 | } | |
810 | ||
811 | EXPORT_SYMBOL(blk_queue_segment_boundary); | |
812 | ||
813 | /** | |
814 | * blk_queue_dma_alignment - set dma length and memory alignment | |
815 | * @q: the request queue for the device | |
816 | * @mask: alignment mask | |
817 | * | |
818 | * description: | |
819 | * set required memory and length aligment for direct dma transactions. | |
820 | * this is used when buiding direct io requests for the queue. | |
821 | * | |
822 | **/ | |
823 | void blk_queue_dma_alignment(request_queue_t *q, int mask) | |
824 | { | |
825 | q->dma_alignment = mask; | |
826 | } | |
827 | ||
828 | EXPORT_SYMBOL(blk_queue_dma_alignment); | |
829 | ||
830 | /** | |
831 | * blk_queue_find_tag - find a request by its tag and queue | |
1da177e4 LT |
832 | * @q: The request queue for the device |
833 | * @tag: The tag of the request | |
834 | * | |
835 | * Notes: | |
836 | * Should be used when a device returns a tag and you want to match | |
837 | * it with a request. | |
838 | * | |
839 | * no locks need be held. | |
840 | **/ | |
841 | struct request *blk_queue_find_tag(request_queue_t *q, int tag) | |
842 | { | |
843 | struct blk_queue_tag *bqt = q->queue_tags; | |
844 | ||
ba025082 | 845 | if (unlikely(bqt == NULL || tag >= bqt->real_max_depth)) |
1da177e4 LT |
846 | return NULL; |
847 | ||
848 | return bqt->tag_index[tag]; | |
849 | } | |
850 | ||
851 | EXPORT_SYMBOL(blk_queue_find_tag); | |
852 | ||
853 | /** | |
492dfb48 JB |
854 | * __blk_free_tags - release a given set of tag maintenance info |
855 | * @bqt: the tag map to free | |
1da177e4 | 856 | * |
492dfb48 JB |
857 | * Tries to free the specified @bqt@. Returns true if it was |
858 | * actually freed and false if there are still references using it | |
859 | */ | |
860 | static int __blk_free_tags(struct blk_queue_tag *bqt) | |
1da177e4 | 861 | { |
492dfb48 | 862 | int retval; |
1da177e4 | 863 | |
492dfb48 JB |
864 | retval = atomic_dec_and_test(&bqt->refcnt); |
865 | if (retval) { | |
1da177e4 LT |
866 | BUG_ON(bqt->busy); |
867 | BUG_ON(!list_empty(&bqt->busy_list)); | |
868 | ||
869 | kfree(bqt->tag_index); | |
870 | bqt->tag_index = NULL; | |
871 | ||
872 | kfree(bqt->tag_map); | |
873 | bqt->tag_map = NULL; | |
874 | ||
875 | kfree(bqt); | |
492dfb48 | 876 | |
1da177e4 LT |
877 | } |
878 | ||
492dfb48 JB |
879 | return retval; |
880 | } | |
881 | ||
882 | /** | |
883 | * __blk_queue_free_tags - release tag maintenance info | |
884 | * @q: the request queue for the device | |
885 | * | |
886 | * Notes: | |
887 | * blk_cleanup_queue() will take care of calling this function, if tagging | |
888 | * has been used. So there's no need to call this directly. | |
889 | **/ | |
890 | static void __blk_queue_free_tags(request_queue_t *q) | |
891 | { | |
892 | struct blk_queue_tag *bqt = q->queue_tags; | |
893 | ||
894 | if (!bqt) | |
895 | return; | |
896 | ||
897 | __blk_free_tags(bqt); | |
898 | ||
1da177e4 LT |
899 | q->queue_tags = NULL; |
900 | q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED); | |
901 | } | |
902 | ||
492dfb48 JB |
903 | |
904 | /** | |
905 | * blk_free_tags - release a given set of tag maintenance info | |
906 | * @bqt: the tag map to free | |
907 | * | |
908 | * For externally managed @bqt@ frees the map. Callers of this | |
909 | * function must guarantee to have released all the queues that | |
910 | * might have been using this tag map. | |
911 | */ | |
912 | void blk_free_tags(struct blk_queue_tag *bqt) | |
913 | { | |
914 | if (unlikely(!__blk_free_tags(bqt))) | |
915 | BUG(); | |
916 | } | |
917 | EXPORT_SYMBOL(blk_free_tags); | |
918 | ||
1da177e4 LT |
919 | /** |
920 | * blk_queue_free_tags - release tag maintenance info | |
921 | * @q: the request queue for the device | |
922 | * | |
923 | * Notes: | |
924 | * This is used to disabled tagged queuing to a device, yet leave | |
925 | * queue in function. | |
926 | **/ | |
927 | void blk_queue_free_tags(request_queue_t *q) | |
928 | { | |
929 | clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); | |
930 | } | |
931 | ||
932 | EXPORT_SYMBOL(blk_queue_free_tags); | |
933 | ||
934 | static int | |
935 | init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth) | |
936 | { | |
1da177e4 LT |
937 | struct request **tag_index; |
938 | unsigned long *tag_map; | |
fa72b903 | 939 | int nr_ulongs; |
1da177e4 | 940 | |
492dfb48 | 941 | if (q && depth > q->nr_requests * 2) { |
1da177e4 LT |
942 | depth = q->nr_requests * 2; |
943 | printk(KERN_ERR "%s: adjusted depth to %d\n", | |
944 | __FUNCTION__, depth); | |
945 | } | |
946 | ||
f68110fc | 947 | tag_index = kzalloc(depth * sizeof(struct request *), GFP_ATOMIC); |
1da177e4 LT |
948 | if (!tag_index) |
949 | goto fail; | |
950 | ||
f7d37d02 | 951 | nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG; |
f68110fc | 952 | tag_map = kzalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC); |
1da177e4 LT |
953 | if (!tag_map) |
954 | goto fail; | |
955 | ||
ba025082 | 956 | tags->real_max_depth = depth; |
1da177e4 | 957 | tags->max_depth = depth; |
1da177e4 LT |
958 | tags->tag_index = tag_index; |
959 | tags->tag_map = tag_map; | |
960 | ||
1da177e4 LT |
961 | return 0; |
962 | fail: | |
963 | kfree(tag_index); | |
964 | return -ENOMEM; | |
965 | } | |
966 | ||
492dfb48 JB |
967 | static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q, |
968 | int depth) | |
969 | { | |
970 | struct blk_queue_tag *tags; | |
971 | ||
972 | tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC); | |
973 | if (!tags) | |
974 | goto fail; | |
975 | ||
976 | if (init_tag_map(q, tags, depth)) | |
977 | goto fail; | |
978 | ||
979 | INIT_LIST_HEAD(&tags->busy_list); | |
980 | tags->busy = 0; | |
981 | atomic_set(&tags->refcnt, 1); | |
982 | return tags; | |
983 | fail: | |
984 | kfree(tags); | |
985 | return NULL; | |
986 | } | |
987 | ||
988 | /** | |
989 | * blk_init_tags - initialize the tag info for an external tag map | |
990 | * @depth: the maximum queue depth supported | |
991 | * @tags: the tag to use | |
992 | **/ | |
993 | struct blk_queue_tag *blk_init_tags(int depth) | |
994 | { | |
995 | return __blk_queue_init_tags(NULL, depth); | |
996 | } | |
997 | EXPORT_SYMBOL(blk_init_tags); | |
998 | ||
1da177e4 LT |
999 | /** |
1000 | * blk_queue_init_tags - initialize the queue tag info | |
1001 | * @q: the request queue for the device | |
1002 | * @depth: the maximum queue depth supported | |
1003 | * @tags: the tag to use | |
1004 | **/ | |
1005 | int blk_queue_init_tags(request_queue_t *q, int depth, | |
1006 | struct blk_queue_tag *tags) | |
1007 | { | |
1008 | int rc; | |
1009 | ||
1010 | BUG_ON(tags && q->queue_tags && tags != q->queue_tags); | |
1011 | ||
1012 | if (!tags && !q->queue_tags) { | |
492dfb48 | 1013 | tags = __blk_queue_init_tags(q, depth); |
1da177e4 | 1014 | |
492dfb48 | 1015 | if (!tags) |
1da177e4 | 1016 | goto fail; |
1da177e4 LT |
1017 | } else if (q->queue_tags) { |
1018 | if ((rc = blk_queue_resize_tags(q, depth))) | |
1019 | return rc; | |
1020 | set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); | |
1021 | return 0; | |
1022 | } else | |
1023 | atomic_inc(&tags->refcnt); | |
1024 | ||
1025 | /* | |
1026 | * assign it, all done | |
1027 | */ | |
1028 | q->queue_tags = tags; | |
1029 | q->queue_flags |= (1 << QUEUE_FLAG_QUEUED); | |
1030 | return 0; | |
1031 | fail: | |
1032 | kfree(tags); | |
1033 | return -ENOMEM; | |
1034 | } | |
1035 | ||
1036 | EXPORT_SYMBOL(blk_queue_init_tags); | |
1037 | ||
1038 | /** | |
1039 | * blk_queue_resize_tags - change the queueing depth | |
1040 | * @q: the request queue for the device | |
1041 | * @new_depth: the new max command queueing depth | |
1042 | * | |
1043 | * Notes: | |
1044 | * Must be called with the queue lock held. | |
1045 | **/ | |
1046 | int blk_queue_resize_tags(request_queue_t *q, int new_depth) | |
1047 | { | |
1048 | struct blk_queue_tag *bqt = q->queue_tags; | |
1049 | struct request **tag_index; | |
1050 | unsigned long *tag_map; | |
fa72b903 | 1051 | int max_depth, nr_ulongs; |
1da177e4 LT |
1052 | |
1053 | if (!bqt) | |
1054 | return -ENXIO; | |
1055 | ||
ba025082 TH |
1056 | /* |
1057 | * if we already have large enough real_max_depth. just | |
1058 | * adjust max_depth. *NOTE* as requests with tag value | |
1059 | * between new_depth and real_max_depth can be in-flight, tag | |
1060 | * map can not be shrunk blindly here. | |
1061 | */ | |
1062 | if (new_depth <= bqt->real_max_depth) { | |
1063 | bqt->max_depth = new_depth; | |
1064 | return 0; | |
1065 | } | |
1066 | ||
492dfb48 JB |
1067 | /* |
1068 | * Currently cannot replace a shared tag map with a new | |
1069 | * one, so error out if this is the case | |
1070 | */ | |
1071 | if (atomic_read(&bqt->refcnt) != 1) | |
1072 | return -EBUSY; | |
1073 | ||
1da177e4 LT |
1074 | /* |
1075 | * save the old state info, so we can copy it back | |
1076 | */ | |
1077 | tag_index = bqt->tag_index; | |
1078 | tag_map = bqt->tag_map; | |
ba025082 | 1079 | max_depth = bqt->real_max_depth; |
1da177e4 LT |
1080 | |
1081 | if (init_tag_map(q, bqt, new_depth)) | |
1082 | return -ENOMEM; | |
1083 | ||
1084 | memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *)); | |
f7d37d02 | 1085 | nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG; |
fa72b903 | 1086 | memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long)); |
1da177e4 LT |
1087 | |
1088 | kfree(tag_index); | |
1089 | kfree(tag_map); | |
1090 | return 0; | |
1091 | } | |
1092 | ||
1093 | EXPORT_SYMBOL(blk_queue_resize_tags); | |
1094 | ||
1095 | /** | |
1096 | * blk_queue_end_tag - end tag operations for a request | |
1097 | * @q: the request queue for the device | |
1098 | * @rq: the request that has completed | |
1099 | * | |
1100 | * Description: | |
1101 | * Typically called when end_that_request_first() returns 0, meaning | |
1102 | * all transfers have been done for a request. It's important to call | |
1103 | * this function before end_that_request_last(), as that will put the | |
1104 | * request back on the free list thus corrupting the internal tag list. | |
1105 | * | |
1106 | * Notes: | |
1107 | * queue lock must be held. | |
1108 | **/ | |
1109 | void blk_queue_end_tag(request_queue_t *q, struct request *rq) | |
1110 | { | |
1111 | struct blk_queue_tag *bqt = q->queue_tags; | |
1112 | int tag = rq->tag; | |
1113 | ||
1114 | BUG_ON(tag == -1); | |
1115 | ||
ba025082 | 1116 | if (unlikely(tag >= bqt->real_max_depth)) |
040c928c TH |
1117 | /* |
1118 | * This can happen after tag depth has been reduced. | |
1119 | * FIXME: how about a warning or info message here? | |
1120 | */ | |
1da177e4 LT |
1121 | return; |
1122 | ||
1123 | if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) { | |
040c928c TH |
1124 | printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n", |
1125 | __FUNCTION__, tag); | |
1da177e4 LT |
1126 | return; |
1127 | } | |
1128 | ||
1129 | list_del_init(&rq->queuelist); | |
4aff5e23 | 1130 | rq->cmd_flags &= ~REQ_QUEUED; |
1da177e4 LT |
1131 | rq->tag = -1; |
1132 | ||
1133 | if (unlikely(bqt->tag_index[tag] == NULL)) | |
040c928c TH |
1134 | printk(KERN_ERR "%s: tag %d is missing\n", |
1135 | __FUNCTION__, tag); | |
1da177e4 LT |
1136 | |
1137 | bqt->tag_index[tag] = NULL; | |
1138 | bqt->busy--; | |
1139 | } | |
1140 | ||
1141 | EXPORT_SYMBOL(blk_queue_end_tag); | |
1142 | ||
1143 | /** | |
1144 | * blk_queue_start_tag - find a free tag and assign it | |
1145 | * @q: the request queue for the device | |
1146 | * @rq: the block request that needs tagging | |
1147 | * | |
1148 | * Description: | |
1149 | * This can either be used as a stand-alone helper, or possibly be | |
1150 | * assigned as the queue &prep_rq_fn (in which case &struct request | |
1151 | * automagically gets a tag assigned). Note that this function | |
1152 | * assumes that any type of request can be queued! if this is not | |
1153 | * true for your device, you must check the request type before | |
1154 | * calling this function. The request will also be removed from | |
1155 | * the request queue, so it's the drivers responsibility to readd | |
1156 | * it if it should need to be restarted for some reason. | |
1157 | * | |
1158 | * Notes: | |
1159 | * queue lock must be held. | |
1160 | **/ | |
1161 | int blk_queue_start_tag(request_queue_t *q, struct request *rq) | |
1162 | { | |
1163 | struct blk_queue_tag *bqt = q->queue_tags; | |
2bf0fdad | 1164 | int tag; |
1da177e4 | 1165 | |
4aff5e23 | 1166 | if (unlikely((rq->cmd_flags & REQ_QUEUED))) { |
1da177e4 | 1167 | printk(KERN_ERR |
040c928c TH |
1168 | "%s: request %p for device [%s] already tagged %d", |
1169 | __FUNCTION__, rq, | |
1170 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag); | |
1da177e4 LT |
1171 | BUG(); |
1172 | } | |
1173 | ||
2bf0fdad TH |
1174 | tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth); |
1175 | if (tag >= bqt->max_depth) | |
1176 | return 1; | |
1da177e4 | 1177 | |
1da177e4 LT |
1178 | __set_bit(tag, bqt->tag_map); |
1179 | ||
4aff5e23 | 1180 | rq->cmd_flags |= REQ_QUEUED; |
1da177e4 LT |
1181 | rq->tag = tag; |
1182 | bqt->tag_index[tag] = rq; | |
1183 | blkdev_dequeue_request(rq); | |
1184 | list_add(&rq->queuelist, &bqt->busy_list); | |
1185 | bqt->busy++; | |
1186 | return 0; | |
1187 | } | |
1188 | ||
1189 | EXPORT_SYMBOL(blk_queue_start_tag); | |
1190 | ||
1191 | /** | |
1192 | * blk_queue_invalidate_tags - invalidate all pending tags | |
1193 | * @q: the request queue for the device | |
1194 | * | |
1195 | * Description: | |
1196 | * Hardware conditions may dictate a need to stop all pending requests. | |
1197 | * In this case, we will safely clear the block side of the tag queue and | |
1198 | * readd all requests to the request queue in the right order. | |
1199 | * | |
1200 | * Notes: | |
1201 | * queue lock must be held. | |
1202 | **/ | |
1203 | void blk_queue_invalidate_tags(request_queue_t *q) | |
1204 | { | |
1205 | struct blk_queue_tag *bqt = q->queue_tags; | |
1206 | struct list_head *tmp, *n; | |
1207 | struct request *rq; | |
1208 | ||
1209 | list_for_each_safe(tmp, n, &bqt->busy_list) { | |
1210 | rq = list_entry_rq(tmp); | |
1211 | ||
1212 | if (rq->tag == -1) { | |
040c928c TH |
1213 | printk(KERN_ERR |
1214 | "%s: bad tag found on list\n", __FUNCTION__); | |
1da177e4 | 1215 | list_del_init(&rq->queuelist); |
4aff5e23 | 1216 | rq->cmd_flags &= ~REQ_QUEUED; |
1da177e4 LT |
1217 | } else |
1218 | blk_queue_end_tag(q, rq); | |
1219 | ||
4aff5e23 | 1220 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 LT |
1221 | __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); |
1222 | } | |
1223 | } | |
1224 | ||
1225 | EXPORT_SYMBOL(blk_queue_invalidate_tags); | |
1226 | ||
1da177e4 LT |
1227 | void blk_dump_rq_flags(struct request *rq, char *msg) |
1228 | { | |
1229 | int bit; | |
1230 | ||
4aff5e23 JA |
1231 | printk("%s: dev %s: type=%x, flags=%x\n", msg, |
1232 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, | |
1233 | rq->cmd_flags); | |
1da177e4 LT |
1234 | |
1235 | printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector, | |
1236 | rq->nr_sectors, | |
1237 | rq->current_nr_sectors); | |
1238 | printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len); | |
1239 | ||
4aff5e23 | 1240 | if (blk_pc_request(rq)) { |
1da177e4 LT |
1241 | printk("cdb: "); |
1242 | for (bit = 0; bit < sizeof(rq->cmd); bit++) | |
1243 | printk("%02x ", rq->cmd[bit]); | |
1244 | printk("\n"); | |
1245 | } | |
1246 | } | |
1247 | ||
1248 | EXPORT_SYMBOL(blk_dump_rq_flags); | |
1249 | ||
1250 | void blk_recount_segments(request_queue_t *q, struct bio *bio) | |
1251 | { | |
1252 | struct bio_vec *bv, *bvprv = NULL; | |
1253 | int i, nr_phys_segs, nr_hw_segs, seg_size, hw_seg_size, cluster; | |
1254 | int high, highprv = 1; | |
1255 | ||
1256 | if (unlikely(!bio->bi_io_vec)) | |
1257 | return; | |
1258 | ||
1259 | cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); | |
1260 | hw_seg_size = seg_size = nr_phys_segs = nr_hw_segs = 0; | |
1261 | bio_for_each_segment(bv, bio, i) { | |
1262 | /* | |
1263 | * the trick here is making sure that a high page is never | |
1264 | * considered part of another segment, since that might | |
1265 | * change with the bounce page. | |
1266 | */ | |
1267 | high = page_to_pfn(bv->bv_page) >= q->bounce_pfn; | |
1268 | if (high || highprv) | |
1269 | goto new_hw_segment; | |
1270 | if (cluster) { | |
1271 | if (seg_size + bv->bv_len > q->max_segment_size) | |
1272 | goto new_segment; | |
1273 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv)) | |
1274 | goto new_segment; | |
1275 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv)) | |
1276 | goto new_segment; | |
1277 | if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) | |
1278 | goto new_hw_segment; | |
1279 | ||
1280 | seg_size += bv->bv_len; | |
1281 | hw_seg_size += bv->bv_len; | |
1282 | bvprv = bv; | |
1283 | continue; | |
1284 | } | |
1285 | new_segment: | |
1286 | if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) && | |
1287 | !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) { | |
1288 | hw_seg_size += bv->bv_len; | |
1289 | } else { | |
1290 | new_hw_segment: | |
1291 | if (hw_seg_size > bio->bi_hw_front_size) | |
1292 | bio->bi_hw_front_size = hw_seg_size; | |
1293 | hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len; | |
1294 | nr_hw_segs++; | |
1295 | } | |
1296 | ||
1297 | nr_phys_segs++; | |
1298 | bvprv = bv; | |
1299 | seg_size = bv->bv_len; | |
1300 | highprv = high; | |
1301 | } | |
1302 | if (hw_seg_size > bio->bi_hw_back_size) | |
1303 | bio->bi_hw_back_size = hw_seg_size; | |
1304 | if (nr_hw_segs == 1 && hw_seg_size > bio->bi_hw_front_size) | |
1305 | bio->bi_hw_front_size = hw_seg_size; | |
1306 | bio->bi_phys_segments = nr_phys_segs; | |
1307 | bio->bi_hw_segments = nr_hw_segs; | |
1308 | bio->bi_flags |= (1 << BIO_SEG_VALID); | |
1309 | } | |
1310 | ||
1311 | ||
93d17d3d | 1312 | static int blk_phys_contig_segment(request_queue_t *q, struct bio *bio, |
1da177e4 LT |
1313 | struct bio *nxt) |
1314 | { | |
1315 | if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER))) | |
1316 | return 0; | |
1317 | ||
1318 | if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt))) | |
1319 | return 0; | |
1320 | if (bio->bi_size + nxt->bi_size > q->max_segment_size) | |
1321 | return 0; | |
1322 | ||
1323 | /* | |
1324 | * bio and nxt are contigous in memory, check if the queue allows | |
1325 | * these two to be merged into one | |
1326 | */ | |
1327 | if (BIO_SEG_BOUNDARY(q, bio, nxt)) | |
1328 | return 1; | |
1329 | ||
1330 | return 0; | |
1331 | } | |
1332 | ||
93d17d3d | 1333 | static int blk_hw_contig_segment(request_queue_t *q, struct bio *bio, |
1da177e4 LT |
1334 | struct bio *nxt) |
1335 | { | |
1336 | if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
1337 | blk_recount_segments(q, bio); | |
1338 | if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID))) | |
1339 | blk_recount_segments(q, nxt); | |
1340 | if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) || | |
1341 | BIOVEC_VIRT_OVERSIZE(bio->bi_hw_front_size + bio->bi_hw_back_size)) | |
1342 | return 0; | |
1343 | if (bio->bi_size + nxt->bi_size > q->max_segment_size) | |
1344 | return 0; | |
1345 | ||
1346 | return 1; | |
1347 | } | |
1348 | ||
1da177e4 LT |
1349 | /* |
1350 | * map a request to scatterlist, return number of sg entries setup. Caller | |
1351 | * must make sure sg can hold rq->nr_phys_segments entries | |
1352 | */ | |
1353 | int blk_rq_map_sg(request_queue_t *q, struct request *rq, struct scatterlist *sg) | |
1354 | { | |
1355 | struct bio_vec *bvec, *bvprv; | |
1356 | struct bio *bio; | |
1357 | int nsegs, i, cluster; | |
1358 | ||
1359 | nsegs = 0; | |
1360 | cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); | |
1361 | ||
1362 | /* | |
1363 | * for each bio in rq | |
1364 | */ | |
1365 | bvprv = NULL; | |
1366 | rq_for_each_bio(bio, rq) { | |
1367 | /* | |
1368 | * for each segment in bio | |
1369 | */ | |
1370 | bio_for_each_segment(bvec, bio, i) { | |
1371 | int nbytes = bvec->bv_len; | |
1372 | ||
1373 | if (bvprv && cluster) { | |
1374 | if (sg[nsegs - 1].length + nbytes > q->max_segment_size) | |
1375 | goto new_segment; | |
1376 | ||
1377 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) | |
1378 | goto new_segment; | |
1379 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) | |
1380 | goto new_segment; | |
1381 | ||
1382 | sg[nsegs - 1].length += nbytes; | |
1383 | } else { | |
1384 | new_segment: | |
1385 | memset(&sg[nsegs],0,sizeof(struct scatterlist)); | |
1386 | sg[nsegs].page = bvec->bv_page; | |
1387 | sg[nsegs].length = nbytes; | |
1388 | sg[nsegs].offset = bvec->bv_offset; | |
1389 | ||
1390 | nsegs++; | |
1391 | } | |
1392 | bvprv = bvec; | |
1393 | } /* segments in bio */ | |
1394 | } /* bios in rq */ | |
1395 | ||
1396 | return nsegs; | |
1397 | } | |
1398 | ||
1399 | EXPORT_SYMBOL(blk_rq_map_sg); | |
1400 | ||
1401 | /* | |
1402 | * the standard queue merge functions, can be overridden with device | |
1403 | * specific ones if so desired | |
1404 | */ | |
1405 | ||
1406 | static inline int ll_new_mergeable(request_queue_t *q, | |
1407 | struct request *req, | |
1408 | struct bio *bio) | |
1409 | { | |
1410 | int nr_phys_segs = bio_phys_segments(q, bio); | |
1411 | ||
1412 | if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { | |
4aff5e23 | 1413 | req->cmd_flags |= REQ_NOMERGE; |
1da177e4 LT |
1414 | if (req == q->last_merge) |
1415 | q->last_merge = NULL; | |
1416 | return 0; | |
1417 | } | |
1418 | ||
1419 | /* | |
1420 | * A hw segment is just getting larger, bump just the phys | |
1421 | * counter. | |
1422 | */ | |
1423 | req->nr_phys_segments += nr_phys_segs; | |
1424 | return 1; | |
1425 | } | |
1426 | ||
1427 | static inline int ll_new_hw_segment(request_queue_t *q, | |
1428 | struct request *req, | |
1429 | struct bio *bio) | |
1430 | { | |
1431 | int nr_hw_segs = bio_hw_segments(q, bio); | |
1432 | int nr_phys_segs = bio_phys_segments(q, bio); | |
1433 | ||
1434 | if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments | |
1435 | || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { | |
4aff5e23 | 1436 | req->cmd_flags |= REQ_NOMERGE; |
1da177e4 LT |
1437 | if (req == q->last_merge) |
1438 | q->last_merge = NULL; | |
1439 | return 0; | |
1440 | } | |
1441 | ||
1442 | /* | |
1443 | * This will form the start of a new hw segment. Bump both | |
1444 | * counters. | |
1445 | */ | |
1446 | req->nr_hw_segments += nr_hw_segs; | |
1447 | req->nr_phys_segments += nr_phys_segs; | |
1448 | return 1; | |
1449 | } | |
1450 | ||
1451 | static int ll_back_merge_fn(request_queue_t *q, struct request *req, | |
1452 | struct bio *bio) | |
1453 | { | |
defd94b7 | 1454 | unsigned short max_sectors; |
1da177e4 LT |
1455 | int len; |
1456 | ||
defd94b7 MC |
1457 | if (unlikely(blk_pc_request(req))) |
1458 | max_sectors = q->max_hw_sectors; | |
1459 | else | |
1460 | max_sectors = q->max_sectors; | |
1461 | ||
1462 | if (req->nr_sectors + bio_sectors(bio) > max_sectors) { | |
4aff5e23 | 1463 | req->cmd_flags |= REQ_NOMERGE; |
1da177e4 LT |
1464 | if (req == q->last_merge) |
1465 | q->last_merge = NULL; | |
1466 | return 0; | |
1467 | } | |
1468 | if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID))) | |
1469 | blk_recount_segments(q, req->biotail); | |
1470 | if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
1471 | blk_recount_segments(q, bio); | |
1472 | len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size; | |
1473 | if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) && | |
1474 | !BIOVEC_VIRT_OVERSIZE(len)) { | |
1475 | int mergeable = ll_new_mergeable(q, req, bio); | |
1476 | ||
1477 | if (mergeable) { | |
1478 | if (req->nr_hw_segments == 1) | |
1479 | req->bio->bi_hw_front_size = len; | |
1480 | if (bio->bi_hw_segments == 1) | |
1481 | bio->bi_hw_back_size = len; | |
1482 | } | |
1483 | return mergeable; | |
1484 | } | |
1485 | ||
1486 | return ll_new_hw_segment(q, req, bio); | |
1487 | } | |
1488 | ||
1489 | static int ll_front_merge_fn(request_queue_t *q, struct request *req, | |
1490 | struct bio *bio) | |
1491 | { | |
defd94b7 | 1492 | unsigned short max_sectors; |
1da177e4 LT |
1493 | int len; |
1494 | ||
defd94b7 MC |
1495 | if (unlikely(blk_pc_request(req))) |
1496 | max_sectors = q->max_hw_sectors; | |
1497 | else | |
1498 | max_sectors = q->max_sectors; | |
1499 | ||
1500 | ||
1501 | if (req->nr_sectors + bio_sectors(bio) > max_sectors) { | |
4aff5e23 | 1502 | req->cmd_flags |= REQ_NOMERGE; |
1da177e4 LT |
1503 | if (req == q->last_merge) |
1504 | q->last_merge = NULL; | |
1505 | return 0; | |
1506 | } | |
1507 | len = bio->bi_hw_back_size + req->bio->bi_hw_front_size; | |
1508 | if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
1509 | blk_recount_segments(q, bio); | |
1510 | if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID))) | |
1511 | blk_recount_segments(q, req->bio); | |
1512 | if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) && | |
1513 | !BIOVEC_VIRT_OVERSIZE(len)) { | |
1514 | int mergeable = ll_new_mergeable(q, req, bio); | |
1515 | ||
1516 | if (mergeable) { | |
1517 | if (bio->bi_hw_segments == 1) | |
1518 | bio->bi_hw_front_size = len; | |
1519 | if (req->nr_hw_segments == 1) | |
1520 | req->biotail->bi_hw_back_size = len; | |
1521 | } | |
1522 | return mergeable; | |
1523 | } | |
1524 | ||
1525 | return ll_new_hw_segment(q, req, bio); | |
1526 | } | |
1527 | ||
1528 | static int ll_merge_requests_fn(request_queue_t *q, struct request *req, | |
1529 | struct request *next) | |
1530 | { | |
dfa1a553 ND |
1531 | int total_phys_segments; |
1532 | int total_hw_segments; | |
1da177e4 LT |
1533 | |
1534 | /* | |
1535 | * First check if the either of the requests are re-queued | |
1536 | * requests. Can't merge them if they are. | |
1537 | */ | |
1538 | if (req->special || next->special) | |
1539 | return 0; | |
1540 | ||
1541 | /* | |
dfa1a553 | 1542 | * Will it become too large? |
1da177e4 LT |
1543 | */ |
1544 | if ((req->nr_sectors + next->nr_sectors) > q->max_sectors) | |
1545 | return 0; | |
1546 | ||
1547 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
1548 | if (blk_phys_contig_segment(q, req->biotail, next->bio)) | |
1549 | total_phys_segments--; | |
1550 | ||
1551 | if (total_phys_segments > q->max_phys_segments) | |
1552 | return 0; | |
1553 | ||
1554 | total_hw_segments = req->nr_hw_segments + next->nr_hw_segments; | |
1555 | if (blk_hw_contig_segment(q, req->biotail, next->bio)) { | |
1556 | int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size; | |
1557 | /* | |
1558 | * propagate the combined length to the end of the requests | |
1559 | */ | |
1560 | if (req->nr_hw_segments == 1) | |
1561 | req->bio->bi_hw_front_size = len; | |
1562 | if (next->nr_hw_segments == 1) | |
1563 | next->biotail->bi_hw_back_size = len; | |
1564 | total_hw_segments--; | |
1565 | } | |
1566 | ||
1567 | if (total_hw_segments > q->max_hw_segments) | |
1568 | return 0; | |
1569 | ||
1570 | /* Merge is OK... */ | |
1571 | req->nr_phys_segments = total_phys_segments; | |
1572 | req->nr_hw_segments = total_hw_segments; | |
1573 | return 1; | |
1574 | } | |
1575 | ||
1576 | /* | |
1577 | * "plug" the device if there are no outstanding requests: this will | |
1578 | * force the transfer to start only after we have put all the requests | |
1579 | * on the list. | |
1580 | * | |
1581 | * This is called with interrupts off and no requests on the queue and | |
1582 | * with the queue lock held. | |
1583 | */ | |
1584 | void blk_plug_device(request_queue_t *q) | |
1585 | { | |
1586 | WARN_ON(!irqs_disabled()); | |
1587 | ||
1588 | /* | |
1589 | * don't plug a stopped queue, it must be paired with blk_start_queue() | |
1590 | * which will restart the queueing | |
1591 | */ | |
7daac490 | 1592 | if (blk_queue_stopped(q)) |
1da177e4 LT |
1593 | return; |
1594 | ||
2056a782 | 1595 | if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) { |
1da177e4 | 1596 | mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); |
2056a782 JA |
1597 | blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG); |
1598 | } | |
1da177e4 LT |
1599 | } |
1600 | ||
1601 | EXPORT_SYMBOL(blk_plug_device); | |
1602 | ||
1603 | /* | |
1604 | * remove the queue from the plugged list, if present. called with | |
1605 | * queue lock held and interrupts disabled. | |
1606 | */ | |
1607 | int blk_remove_plug(request_queue_t *q) | |
1608 | { | |
1609 | WARN_ON(!irqs_disabled()); | |
1610 | ||
1611 | if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) | |
1612 | return 0; | |
1613 | ||
1614 | del_timer(&q->unplug_timer); | |
1615 | return 1; | |
1616 | } | |
1617 | ||
1618 | EXPORT_SYMBOL(blk_remove_plug); | |
1619 | ||
1620 | /* | |
1621 | * remove the plug and let it rip.. | |
1622 | */ | |
1623 | void __generic_unplug_device(request_queue_t *q) | |
1624 | { | |
7daac490 | 1625 | if (unlikely(blk_queue_stopped(q))) |
1da177e4 LT |
1626 | return; |
1627 | ||
1628 | if (!blk_remove_plug(q)) | |
1629 | return; | |
1630 | ||
22e2c507 | 1631 | q->request_fn(q); |
1da177e4 LT |
1632 | } |
1633 | EXPORT_SYMBOL(__generic_unplug_device); | |
1634 | ||
1635 | /** | |
1636 | * generic_unplug_device - fire a request queue | |
1637 | * @q: The &request_queue_t in question | |
1638 | * | |
1639 | * Description: | |
1640 | * Linux uses plugging to build bigger requests queues before letting | |
1641 | * the device have at them. If a queue is plugged, the I/O scheduler | |
1642 | * is still adding and merging requests on the queue. Once the queue | |
1643 | * gets unplugged, the request_fn defined for the queue is invoked and | |
1644 | * transfers started. | |
1645 | **/ | |
1646 | void generic_unplug_device(request_queue_t *q) | |
1647 | { | |
1648 | spin_lock_irq(q->queue_lock); | |
1649 | __generic_unplug_device(q); | |
1650 | spin_unlock_irq(q->queue_lock); | |
1651 | } | |
1652 | EXPORT_SYMBOL(generic_unplug_device); | |
1653 | ||
1654 | static void blk_backing_dev_unplug(struct backing_dev_info *bdi, | |
1655 | struct page *page) | |
1656 | { | |
1657 | request_queue_t *q = bdi->unplug_io_data; | |
1658 | ||
1659 | /* | |
1660 | * devices don't necessarily have an ->unplug_fn defined | |
1661 | */ | |
2056a782 JA |
1662 | if (q->unplug_fn) { |
1663 | blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, | |
1664 | q->rq.count[READ] + q->rq.count[WRITE]); | |
1665 | ||
1da177e4 | 1666 | q->unplug_fn(q); |
2056a782 | 1667 | } |
1da177e4 LT |
1668 | } |
1669 | ||
1670 | static void blk_unplug_work(void *data) | |
1671 | { | |
1672 | request_queue_t *q = data; | |
1673 | ||
2056a782 JA |
1674 | blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, |
1675 | q->rq.count[READ] + q->rq.count[WRITE]); | |
1676 | ||
1da177e4 LT |
1677 | q->unplug_fn(q); |
1678 | } | |
1679 | ||
1680 | static void blk_unplug_timeout(unsigned long data) | |
1681 | { | |
1682 | request_queue_t *q = (request_queue_t *)data; | |
1683 | ||
2056a782 JA |
1684 | blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL, |
1685 | q->rq.count[READ] + q->rq.count[WRITE]); | |
1686 | ||
1da177e4 LT |
1687 | kblockd_schedule_work(&q->unplug_work); |
1688 | } | |
1689 | ||
1690 | /** | |
1691 | * blk_start_queue - restart a previously stopped queue | |
1692 | * @q: The &request_queue_t in question | |
1693 | * | |
1694 | * Description: | |
1695 | * blk_start_queue() will clear the stop flag on the queue, and call | |
1696 | * the request_fn for the queue if it was in a stopped state when | |
1697 | * entered. Also see blk_stop_queue(). Queue lock must be held. | |
1698 | **/ | |
1699 | void blk_start_queue(request_queue_t *q) | |
1700 | { | |
a038e253 PBG |
1701 | WARN_ON(!irqs_disabled()); |
1702 | ||
1da177e4 LT |
1703 | clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); |
1704 | ||
1705 | /* | |
1706 | * one level of recursion is ok and is much faster than kicking | |
1707 | * the unplug handling | |
1708 | */ | |
1709 | if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { | |
1710 | q->request_fn(q); | |
1711 | clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); | |
1712 | } else { | |
1713 | blk_plug_device(q); | |
1714 | kblockd_schedule_work(&q->unplug_work); | |
1715 | } | |
1716 | } | |
1717 | ||
1718 | EXPORT_SYMBOL(blk_start_queue); | |
1719 | ||
1720 | /** | |
1721 | * blk_stop_queue - stop a queue | |
1722 | * @q: The &request_queue_t in question | |
1723 | * | |
1724 | * Description: | |
1725 | * The Linux block layer assumes that a block driver will consume all | |
1726 | * entries on the request queue when the request_fn strategy is called. | |
1727 | * Often this will not happen, because of hardware limitations (queue | |
1728 | * depth settings). If a device driver gets a 'queue full' response, | |
1729 | * or if it simply chooses not to queue more I/O at one point, it can | |
1730 | * call this function to prevent the request_fn from being called until | |
1731 | * the driver has signalled it's ready to go again. This happens by calling | |
1732 | * blk_start_queue() to restart queue operations. Queue lock must be held. | |
1733 | **/ | |
1734 | void blk_stop_queue(request_queue_t *q) | |
1735 | { | |
1736 | blk_remove_plug(q); | |
1737 | set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); | |
1738 | } | |
1739 | EXPORT_SYMBOL(blk_stop_queue); | |
1740 | ||
1741 | /** | |
1742 | * blk_sync_queue - cancel any pending callbacks on a queue | |
1743 | * @q: the queue | |
1744 | * | |
1745 | * Description: | |
1746 | * The block layer may perform asynchronous callback activity | |
1747 | * on a queue, such as calling the unplug function after a timeout. | |
1748 | * A block device may call blk_sync_queue to ensure that any | |
1749 | * such activity is cancelled, thus allowing it to release resources | |
1750 | * the the callbacks might use. The caller must already have made sure | |
1751 | * that its ->make_request_fn will not re-add plugging prior to calling | |
1752 | * this function. | |
1753 | * | |
1754 | */ | |
1755 | void blk_sync_queue(struct request_queue *q) | |
1756 | { | |
1757 | del_timer_sync(&q->unplug_timer); | |
1758 | kblockd_flush(); | |
1759 | } | |
1760 | EXPORT_SYMBOL(blk_sync_queue); | |
1761 | ||
1762 | /** | |
1763 | * blk_run_queue - run a single device queue | |
1764 | * @q: The queue to run | |
1765 | */ | |
1766 | void blk_run_queue(struct request_queue *q) | |
1767 | { | |
1768 | unsigned long flags; | |
1769 | ||
1770 | spin_lock_irqsave(q->queue_lock, flags); | |
1771 | blk_remove_plug(q); | |
dac07ec1 JA |
1772 | |
1773 | /* | |
1774 | * Only recurse once to avoid overrunning the stack, let the unplug | |
1775 | * handling reinvoke the handler shortly if we already got there. | |
1776 | */ | |
1777 | if (!elv_queue_empty(q)) { | |
1778 | if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { | |
1779 | q->request_fn(q); | |
1780 | clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); | |
1781 | } else { | |
1782 | blk_plug_device(q); | |
1783 | kblockd_schedule_work(&q->unplug_work); | |
1784 | } | |
1785 | } | |
1786 | ||
1da177e4 LT |
1787 | spin_unlock_irqrestore(q->queue_lock, flags); |
1788 | } | |
1789 | EXPORT_SYMBOL(blk_run_queue); | |
1790 | ||
1791 | /** | |
1792 | * blk_cleanup_queue: - release a &request_queue_t when it is no longer needed | |
a580290c | 1793 | * @kobj: the kobj belonging of the request queue to be released |
1da177e4 LT |
1794 | * |
1795 | * Description: | |
1796 | * blk_cleanup_queue is the pair to blk_init_queue() or | |
1797 | * blk_queue_make_request(). It should be called when a request queue is | |
1798 | * being released; typically when a block device is being de-registered. | |
1799 | * Currently, its primary task it to free all the &struct request | |
1800 | * structures that were allocated to the queue and the queue itself. | |
1801 | * | |
1802 | * Caveat: | |
1803 | * Hopefully the low level driver will have finished any | |
1804 | * outstanding requests first... | |
1805 | **/ | |
483f4afc | 1806 | static void blk_release_queue(struct kobject *kobj) |
1da177e4 | 1807 | { |
483f4afc | 1808 | request_queue_t *q = container_of(kobj, struct request_queue, kobj); |
1da177e4 LT |
1809 | struct request_list *rl = &q->rq; |
1810 | ||
1da177e4 LT |
1811 | blk_sync_queue(q); |
1812 | ||
1813 | if (rl->rq_pool) | |
1814 | mempool_destroy(rl->rq_pool); | |
1815 | ||
1816 | if (q->queue_tags) | |
1817 | __blk_queue_free_tags(q); | |
1818 | ||
6c5c9341 | 1819 | blk_trace_shutdown(q); |
2056a782 | 1820 | |
1da177e4 LT |
1821 | kmem_cache_free(requestq_cachep, q); |
1822 | } | |
1823 | ||
483f4afc AV |
1824 | void blk_put_queue(request_queue_t *q) |
1825 | { | |
1826 | kobject_put(&q->kobj); | |
1827 | } | |
1828 | EXPORT_SYMBOL(blk_put_queue); | |
1829 | ||
1830 | void blk_cleanup_queue(request_queue_t * q) | |
1831 | { | |
1832 | mutex_lock(&q->sysfs_lock); | |
1833 | set_bit(QUEUE_FLAG_DEAD, &q->queue_flags); | |
1834 | mutex_unlock(&q->sysfs_lock); | |
1835 | ||
1836 | if (q->elevator) | |
1837 | elevator_exit(q->elevator); | |
1838 | ||
1839 | blk_put_queue(q); | |
1840 | } | |
1841 | ||
1da177e4 LT |
1842 | EXPORT_SYMBOL(blk_cleanup_queue); |
1843 | ||
1844 | static int blk_init_free_list(request_queue_t *q) | |
1845 | { | |
1846 | struct request_list *rl = &q->rq; | |
1847 | ||
1848 | rl->count[READ] = rl->count[WRITE] = 0; | |
1849 | rl->starved[READ] = rl->starved[WRITE] = 0; | |
cb98fc8b | 1850 | rl->elvpriv = 0; |
1da177e4 LT |
1851 | init_waitqueue_head(&rl->wait[READ]); |
1852 | init_waitqueue_head(&rl->wait[WRITE]); | |
1da177e4 | 1853 | |
1946089a CL |
1854 | rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
1855 | mempool_free_slab, request_cachep, q->node); | |
1da177e4 LT |
1856 | |
1857 | if (!rl->rq_pool) | |
1858 | return -ENOMEM; | |
1859 | ||
1860 | return 0; | |
1861 | } | |
1862 | ||
8267e268 | 1863 | request_queue_t *blk_alloc_queue(gfp_t gfp_mask) |
1da177e4 | 1864 | { |
1946089a CL |
1865 | return blk_alloc_queue_node(gfp_mask, -1); |
1866 | } | |
1867 | EXPORT_SYMBOL(blk_alloc_queue); | |
1da177e4 | 1868 | |
483f4afc AV |
1869 | static struct kobj_type queue_ktype; |
1870 | ||
8267e268 | 1871 | request_queue_t *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) |
1946089a CL |
1872 | { |
1873 | request_queue_t *q; | |
1874 | ||
1875 | q = kmem_cache_alloc_node(requestq_cachep, gfp_mask, node_id); | |
1da177e4 LT |
1876 | if (!q) |
1877 | return NULL; | |
1878 | ||
1879 | memset(q, 0, sizeof(*q)); | |
1880 | init_timer(&q->unplug_timer); | |
483f4afc AV |
1881 | |
1882 | snprintf(q->kobj.name, KOBJ_NAME_LEN, "%s", "queue"); | |
1883 | q->kobj.ktype = &queue_ktype; | |
1884 | kobject_init(&q->kobj); | |
1da177e4 LT |
1885 | |
1886 | q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; | |
1887 | q->backing_dev_info.unplug_io_data = q; | |
1888 | ||
483f4afc AV |
1889 | mutex_init(&q->sysfs_lock); |
1890 | ||
1da177e4 LT |
1891 | return q; |
1892 | } | |
1946089a | 1893 | EXPORT_SYMBOL(blk_alloc_queue_node); |
1da177e4 LT |
1894 | |
1895 | /** | |
1896 | * blk_init_queue - prepare a request queue for use with a block device | |
1897 | * @rfn: The function to be called to process requests that have been | |
1898 | * placed on the queue. | |
1899 | * @lock: Request queue spin lock | |
1900 | * | |
1901 | * Description: | |
1902 | * If a block device wishes to use the standard request handling procedures, | |
1903 | * which sorts requests and coalesces adjacent requests, then it must | |
1904 | * call blk_init_queue(). The function @rfn will be called when there | |
1905 | * are requests on the queue that need to be processed. If the device | |
1906 | * supports plugging, then @rfn may not be called immediately when requests | |
1907 | * are available on the queue, but may be called at some time later instead. | |
1908 | * Plugged queues are generally unplugged when a buffer belonging to one | |
1909 | * of the requests on the queue is needed, or due to memory pressure. | |
1910 | * | |
1911 | * @rfn is not required, or even expected, to remove all requests off the | |
1912 | * queue, but only as many as it can handle at a time. If it does leave | |
1913 | * requests on the queue, it is responsible for arranging that the requests | |
1914 | * get dealt with eventually. | |
1915 | * | |
1916 | * The queue spin lock must be held while manipulating the requests on the | |
a038e253 PBG |
1917 | * request queue; this lock will be taken also from interrupt context, so irq |
1918 | * disabling is needed for it. | |
1da177e4 LT |
1919 | * |
1920 | * Function returns a pointer to the initialized request queue, or NULL if | |
1921 | * it didn't succeed. | |
1922 | * | |
1923 | * Note: | |
1924 | * blk_init_queue() must be paired with a blk_cleanup_queue() call | |
1925 | * when the block device is deactivated (such as at module unload). | |
1926 | **/ | |
1946089a | 1927 | |
1da177e4 LT |
1928 | request_queue_t *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) |
1929 | { | |
1946089a CL |
1930 | return blk_init_queue_node(rfn, lock, -1); |
1931 | } | |
1932 | EXPORT_SYMBOL(blk_init_queue); | |
1933 | ||
1934 | request_queue_t * | |
1935 | blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) | |
1936 | { | |
1937 | request_queue_t *q = blk_alloc_queue_node(GFP_KERNEL, node_id); | |
1da177e4 LT |
1938 | |
1939 | if (!q) | |
1940 | return NULL; | |
1941 | ||
1946089a | 1942 | q->node = node_id; |
8669aafd AV |
1943 | if (blk_init_free_list(q)) { |
1944 | kmem_cache_free(requestq_cachep, q); | |
1945 | return NULL; | |
1946 | } | |
1da177e4 | 1947 | |
152587de JA |
1948 | /* |
1949 | * if caller didn't supply a lock, they get per-queue locking with | |
1950 | * our embedded lock | |
1951 | */ | |
1952 | if (!lock) { | |
1953 | spin_lock_init(&q->__queue_lock); | |
1954 | lock = &q->__queue_lock; | |
1955 | } | |
1956 | ||
1da177e4 LT |
1957 | q->request_fn = rfn; |
1958 | q->back_merge_fn = ll_back_merge_fn; | |
1959 | q->front_merge_fn = ll_front_merge_fn; | |
1960 | q->merge_requests_fn = ll_merge_requests_fn; | |
1961 | q->prep_rq_fn = NULL; | |
1962 | q->unplug_fn = generic_unplug_device; | |
1963 | q->queue_flags = (1 << QUEUE_FLAG_CLUSTER); | |
1964 | q->queue_lock = lock; | |
1965 | ||
1966 | blk_queue_segment_boundary(q, 0xffffffff); | |
1967 | ||
1968 | blk_queue_make_request(q, __make_request); | |
1969 | blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE); | |
1970 | ||
1971 | blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); | |
1972 | blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); | |
1973 | ||
1974 | /* | |
1975 | * all done | |
1976 | */ | |
1977 | if (!elevator_init(q, NULL)) { | |
1978 | blk_queue_congestion_threshold(q); | |
1979 | return q; | |
1980 | } | |
1981 | ||
8669aafd | 1982 | blk_put_queue(q); |
1da177e4 LT |
1983 | return NULL; |
1984 | } | |
1946089a | 1985 | EXPORT_SYMBOL(blk_init_queue_node); |
1da177e4 LT |
1986 | |
1987 | int blk_get_queue(request_queue_t *q) | |
1988 | { | |
fde6ad22 | 1989 | if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { |
483f4afc | 1990 | kobject_get(&q->kobj); |
1da177e4 LT |
1991 | return 0; |
1992 | } | |
1993 | ||
1994 | return 1; | |
1995 | } | |
1996 | ||
1997 | EXPORT_SYMBOL(blk_get_queue); | |
1998 | ||
1999 | static inline void blk_free_request(request_queue_t *q, struct request *rq) | |
2000 | { | |
4aff5e23 | 2001 | if (rq->cmd_flags & REQ_ELVPRIV) |
cb98fc8b | 2002 | elv_put_request(q, rq); |
1da177e4 LT |
2003 | mempool_free(rq, q->rq.rq_pool); |
2004 | } | |
2005 | ||
22e2c507 | 2006 | static inline struct request * |
cb98fc8b | 2007 | blk_alloc_request(request_queue_t *q, int rw, struct bio *bio, |
5dd96249 | 2008 | int priv, gfp_t gfp_mask) |
1da177e4 LT |
2009 | { |
2010 | struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); | |
2011 | ||
2012 | if (!rq) | |
2013 | return NULL; | |
2014 | ||
2015 | /* | |
4aff5e23 | 2016 | * first three bits are identical in rq->cmd_flags and bio->bi_rw, |
1da177e4 LT |
2017 | * see bio.h and blkdev.h |
2018 | */ | |
4aff5e23 | 2019 | rq->cmd_flags = rw; |
1da177e4 | 2020 | |
cb98fc8b TH |
2021 | if (priv) { |
2022 | if (unlikely(elv_set_request(q, rq, bio, gfp_mask))) { | |
2023 | mempool_free(rq, q->rq.rq_pool); | |
2024 | return NULL; | |
2025 | } | |
4aff5e23 | 2026 | rq->cmd_flags |= REQ_ELVPRIV; |
cb98fc8b | 2027 | } |
1da177e4 | 2028 | |
cb98fc8b | 2029 | return rq; |
1da177e4 LT |
2030 | } |
2031 | ||
2032 | /* | |
2033 | * ioc_batching returns true if the ioc is a valid batching request and | |
2034 | * should be given priority access to a request. | |
2035 | */ | |
2036 | static inline int ioc_batching(request_queue_t *q, struct io_context *ioc) | |
2037 | { | |
2038 | if (!ioc) | |
2039 | return 0; | |
2040 | ||
2041 | /* | |
2042 | * Make sure the process is able to allocate at least 1 request | |
2043 | * even if the batch times out, otherwise we could theoretically | |
2044 | * lose wakeups. | |
2045 | */ | |
2046 | return ioc->nr_batch_requests == q->nr_batching || | |
2047 | (ioc->nr_batch_requests > 0 | |
2048 | && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); | |
2049 | } | |
2050 | ||
2051 | /* | |
2052 | * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This | |
2053 | * will cause the process to be a "batcher" on all queues in the system. This | |
2054 | * is the behaviour we want though - once it gets a wakeup it should be given | |
2055 | * a nice run. | |
2056 | */ | |
93d17d3d | 2057 | static void ioc_set_batching(request_queue_t *q, struct io_context *ioc) |
1da177e4 LT |
2058 | { |
2059 | if (!ioc || ioc_batching(q, ioc)) | |
2060 | return; | |
2061 | ||
2062 | ioc->nr_batch_requests = q->nr_batching; | |
2063 | ioc->last_waited = jiffies; | |
2064 | } | |
2065 | ||
2066 | static void __freed_request(request_queue_t *q, int rw) | |
2067 | { | |
2068 | struct request_list *rl = &q->rq; | |
2069 | ||
2070 | if (rl->count[rw] < queue_congestion_off_threshold(q)) | |
2071 | clear_queue_congested(q, rw); | |
2072 | ||
2073 | if (rl->count[rw] + 1 <= q->nr_requests) { | |
1da177e4 LT |
2074 | if (waitqueue_active(&rl->wait[rw])) |
2075 | wake_up(&rl->wait[rw]); | |
2076 | ||
2077 | blk_clear_queue_full(q, rw); | |
2078 | } | |
2079 | } | |
2080 | ||
2081 | /* | |
2082 | * A request has just been released. Account for it, update the full and | |
2083 | * congestion status, wake up any waiters. Called under q->queue_lock. | |
2084 | */ | |
cb98fc8b | 2085 | static void freed_request(request_queue_t *q, int rw, int priv) |
1da177e4 LT |
2086 | { |
2087 | struct request_list *rl = &q->rq; | |
2088 | ||
2089 | rl->count[rw]--; | |
cb98fc8b TH |
2090 | if (priv) |
2091 | rl->elvpriv--; | |
1da177e4 LT |
2092 | |
2093 | __freed_request(q, rw); | |
2094 | ||
2095 | if (unlikely(rl->starved[rw ^ 1])) | |
2096 | __freed_request(q, rw ^ 1); | |
1da177e4 LT |
2097 | } |
2098 | ||
2099 | #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist) | |
2100 | /* | |
d6344532 NP |
2101 | * Get a free request, queue_lock must be held. |
2102 | * Returns NULL on failure, with queue_lock held. | |
2103 | * Returns !NULL on success, with queue_lock *not held*. | |
1da177e4 | 2104 | */ |
22e2c507 | 2105 | static struct request *get_request(request_queue_t *q, int rw, struct bio *bio, |
8267e268 | 2106 | gfp_t gfp_mask) |
1da177e4 LT |
2107 | { |
2108 | struct request *rq = NULL; | |
2109 | struct request_list *rl = &q->rq; | |
88ee5ef1 JA |
2110 | struct io_context *ioc = NULL; |
2111 | int may_queue, priv; | |
2112 | ||
2113 | may_queue = elv_may_queue(q, rw, bio); | |
2114 | if (may_queue == ELV_MQUEUE_NO) | |
2115 | goto rq_starved; | |
2116 | ||
2117 | if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) { | |
2118 | if (rl->count[rw]+1 >= q->nr_requests) { | |
2119 | ioc = current_io_context(GFP_ATOMIC); | |
2120 | /* | |
2121 | * The queue will fill after this allocation, so set | |
2122 | * it as full, and mark this process as "batching". | |
2123 | * This process will be allowed to complete a batch of | |
2124 | * requests, others will be blocked. | |
2125 | */ | |
2126 | if (!blk_queue_full(q, rw)) { | |
2127 | ioc_set_batching(q, ioc); | |
2128 | blk_set_queue_full(q, rw); | |
2129 | } else { | |
2130 | if (may_queue != ELV_MQUEUE_MUST | |
2131 | && !ioc_batching(q, ioc)) { | |
2132 | /* | |
2133 | * The queue is full and the allocating | |
2134 | * process is not a "batcher", and not | |
2135 | * exempted by the IO scheduler | |
2136 | */ | |
2137 | goto out; | |
2138 | } | |
2139 | } | |
1da177e4 | 2140 | } |
88ee5ef1 | 2141 | set_queue_congested(q, rw); |
1da177e4 LT |
2142 | } |
2143 | ||
082cf69e JA |
2144 | /* |
2145 | * Only allow batching queuers to allocate up to 50% over the defined | |
2146 | * limit of requests, otherwise we could have thousands of requests | |
2147 | * allocated with any setting of ->nr_requests | |
2148 | */ | |
fd782a4a | 2149 | if (rl->count[rw] >= (3 * q->nr_requests / 2)) |
082cf69e | 2150 | goto out; |
fd782a4a | 2151 | |
1da177e4 LT |
2152 | rl->count[rw]++; |
2153 | rl->starved[rw] = 0; | |
cb98fc8b | 2154 | |
64521d1a | 2155 | priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
cb98fc8b TH |
2156 | if (priv) |
2157 | rl->elvpriv++; | |
2158 | ||
1da177e4 LT |
2159 | spin_unlock_irq(q->queue_lock); |
2160 | ||
cb98fc8b | 2161 | rq = blk_alloc_request(q, rw, bio, priv, gfp_mask); |
88ee5ef1 | 2162 | if (unlikely(!rq)) { |
1da177e4 LT |
2163 | /* |
2164 | * Allocation failed presumably due to memory. Undo anything | |
2165 | * we might have messed up. | |
2166 | * | |
2167 | * Allocating task should really be put onto the front of the | |
2168 | * wait queue, but this is pretty rare. | |
2169 | */ | |
2170 | spin_lock_irq(q->queue_lock); | |
cb98fc8b | 2171 | freed_request(q, rw, priv); |
1da177e4 LT |
2172 | |
2173 | /* | |
2174 | * in the very unlikely event that allocation failed and no | |
2175 | * requests for this direction was pending, mark us starved | |
2176 | * so that freeing of a request in the other direction will | |
2177 | * notice us. another possible fix would be to split the | |
2178 | * rq mempool into READ and WRITE | |
2179 | */ | |
2180 | rq_starved: | |
2181 | if (unlikely(rl->count[rw] == 0)) | |
2182 | rl->starved[rw] = 1; | |
2183 | ||
1da177e4 LT |
2184 | goto out; |
2185 | } | |
2186 | ||
88ee5ef1 JA |
2187 | /* |
2188 | * ioc may be NULL here, and ioc_batching will be false. That's | |
2189 | * OK, if the queue is under the request limit then requests need | |
2190 | * not count toward the nr_batch_requests limit. There will always | |
2191 | * be some limit enforced by BLK_BATCH_TIME. | |
2192 | */ | |
1da177e4 LT |
2193 | if (ioc_batching(q, ioc)) |
2194 | ioc->nr_batch_requests--; | |
2195 | ||
2196 | rq_init(q, rq); | |
2197 | rq->rl = rl; | |
2056a782 JA |
2198 | |
2199 | blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ); | |
1da177e4 | 2200 | out: |
1da177e4 LT |
2201 | return rq; |
2202 | } | |
2203 | ||
2204 | /* | |
2205 | * No available requests for this queue, unplug the device and wait for some | |
2206 | * requests to become available. | |
d6344532 NP |
2207 | * |
2208 | * Called with q->queue_lock held, and returns with it unlocked. | |
1da177e4 | 2209 | */ |
22e2c507 JA |
2210 | static struct request *get_request_wait(request_queue_t *q, int rw, |
2211 | struct bio *bio) | |
1da177e4 | 2212 | { |
1da177e4 LT |
2213 | struct request *rq; |
2214 | ||
450991bc NP |
2215 | rq = get_request(q, rw, bio, GFP_NOIO); |
2216 | while (!rq) { | |
2217 | DEFINE_WAIT(wait); | |
1da177e4 LT |
2218 | struct request_list *rl = &q->rq; |
2219 | ||
2220 | prepare_to_wait_exclusive(&rl->wait[rw], &wait, | |
2221 | TASK_UNINTERRUPTIBLE); | |
2222 | ||
22e2c507 | 2223 | rq = get_request(q, rw, bio, GFP_NOIO); |
1da177e4 LT |
2224 | |
2225 | if (!rq) { | |
2226 | struct io_context *ioc; | |
2227 | ||
2056a782 JA |
2228 | blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ); |
2229 | ||
d6344532 NP |
2230 | __generic_unplug_device(q); |
2231 | spin_unlock_irq(q->queue_lock); | |
1da177e4 LT |
2232 | io_schedule(); |
2233 | ||
2234 | /* | |
2235 | * After sleeping, we become a "batching" process and | |
2236 | * will be able to allocate at least one request, and | |
2237 | * up to a big batch of them for a small period time. | |
2238 | * See ioc_batching, ioc_set_batching | |
2239 | */ | |
fb3cc432 | 2240 | ioc = current_io_context(GFP_NOIO); |
1da177e4 | 2241 | ioc_set_batching(q, ioc); |
d6344532 NP |
2242 | |
2243 | spin_lock_irq(q->queue_lock); | |
1da177e4 LT |
2244 | } |
2245 | finish_wait(&rl->wait[rw], &wait); | |
450991bc | 2246 | } |
1da177e4 LT |
2247 | |
2248 | return rq; | |
2249 | } | |
2250 | ||
8267e268 | 2251 | struct request *blk_get_request(request_queue_t *q, int rw, gfp_t gfp_mask) |
1da177e4 LT |
2252 | { |
2253 | struct request *rq; | |
2254 | ||
2255 | BUG_ON(rw != READ && rw != WRITE); | |
2256 | ||
d6344532 NP |
2257 | spin_lock_irq(q->queue_lock); |
2258 | if (gfp_mask & __GFP_WAIT) { | |
22e2c507 | 2259 | rq = get_request_wait(q, rw, NULL); |
d6344532 | 2260 | } else { |
22e2c507 | 2261 | rq = get_request(q, rw, NULL, gfp_mask); |
d6344532 NP |
2262 | if (!rq) |
2263 | spin_unlock_irq(q->queue_lock); | |
2264 | } | |
2265 | /* q->queue_lock is unlocked at this point */ | |
1da177e4 LT |
2266 | |
2267 | return rq; | |
2268 | } | |
1da177e4 LT |
2269 | EXPORT_SYMBOL(blk_get_request); |
2270 | ||
2271 | /** | |
2272 | * blk_requeue_request - put a request back on queue | |
2273 | * @q: request queue where request should be inserted | |
2274 | * @rq: request to be inserted | |
2275 | * | |
2276 | * Description: | |
2277 | * Drivers often keep queueing requests until the hardware cannot accept | |
2278 | * more, when that condition happens we need to put the request back | |
2279 | * on the queue. Must be called with queue lock held. | |
2280 | */ | |
2281 | void blk_requeue_request(request_queue_t *q, struct request *rq) | |
2282 | { | |
2056a782 JA |
2283 | blk_add_trace_rq(q, rq, BLK_TA_REQUEUE); |
2284 | ||
1da177e4 LT |
2285 | if (blk_rq_tagged(rq)) |
2286 | blk_queue_end_tag(q, rq); | |
2287 | ||
2288 | elv_requeue_request(q, rq); | |
2289 | } | |
2290 | ||
2291 | EXPORT_SYMBOL(blk_requeue_request); | |
2292 | ||
2293 | /** | |
2294 | * blk_insert_request - insert a special request in to a request queue | |
2295 | * @q: request queue where request should be inserted | |
2296 | * @rq: request to be inserted | |
2297 | * @at_head: insert request at head or tail of queue | |
2298 | * @data: private data | |
1da177e4 LT |
2299 | * |
2300 | * Description: | |
2301 | * Many block devices need to execute commands asynchronously, so they don't | |
2302 | * block the whole kernel from preemption during request execution. This is | |
2303 | * accomplished normally by inserting aritficial requests tagged as | |
2304 | * REQ_SPECIAL in to the corresponding request queue, and letting them be | |
2305 | * scheduled for actual execution by the request queue. | |
2306 | * | |
2307 | * We have the option of inserting the head or the tail of the queue. | |
2308 | * Typically we use the tail for new ioctls and so forth. We use the head | |
2309 | * of the queue for things like a QUEUE_FULL message from a device, or a | |
2310 | * host that is unable to accept a particular command. | |
2311 | */ | |
2312 | void blk_insert_request(request_queue_t *q, struct request *rq, | |
867d1191 | 2313 | int at_head, void *data) |
1da177e4 | 2314 | { |
867d1191 | 2315 | int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; |
1da177e4 LT |
2316 | unsigned long flags; |
2317 | ||
2318 | /* | |
2319 | * tell I/O scheduler that this isn't a regular read/write (ie it | |
2320 | * must not attempt merges on this) and that it acts as a soft | |
2321 | * barrier | |
2322 | */ | |
4aff5e23 JA |
2323 | rq->cmd_type = REQ_TYPE_SPECIAL; |
2324 | rq->cmd_flags |= REQ_SOFTBARRIER; | |
1da177e4 LT |
2325 | |
2326 | rq->special = data; | |
2327 | ||
2328 | spin_lock_irqsave(q->queue_lock, flags); | |
2329 | ||
2330 | /* | |
2331 | * If command is tagged, release the tag | |
2332 | */ | |
867d1191 TH |
2333 | if (blk_rq_tagged(rq)) |
2334 | blk_queue_end_tag(q, rq); | |
1da177e4 | 2335 | |
867d1191 TH |
2336 | drive_stat_acct(rq, rq->nr_sectors, 1); |
2337 | __elv_add_request(q, rq, where, 0); | |
1da177e4 | 2338 | |
1da177e4 LT |
2339 | if (blk_queue_plugged(q)) |
2340 | __generic_unplug_device(q); | |
2341 | else | |
2342 | q->request_fn(q); | |
2343 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2344 | } | |
2345 | ||
2346 | EXPORT_SYMBOL(blk_insert_request); | |
2347 | ||
2348 | /** | |
2349 | * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage | |
2350 | * @q: request queue where request should be inserted | |
73747aed | 2351 | * @rq: request structure to fill |
1da177e4 LT |
2352 | * @ubuf: the user buffer |
2353 | * @len: length of user data | |
2354 | * | |
2355 | * Description: | |
2356 | * Data will be mapped directly for zero copy io, if possible. Otherwise | |
2357 | * a kernel bounce buffer is used. | |
2358 | * | |
2359 | * A matching blk_rq_unmap_user() must be issued at the end of io, while | |
2360 | * still in process context. | |
2361 | * | |
2362 | * Note: The mapped bio may need to be bounced through blk_queue_bounce() | |
2363 | * before being submitted to the device, as pages mapped may be out of | |
2364 | * reach. It's the callers responsibility to make sure this happens. The | |
2365 | * original bio must be passed back in to blk_rq_unmap_user() for proper | |
2366 | * unmapping. | |
2367 | */ | |
dd1cab95 JA |
2368 | int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf, |
2369 | unsigned int len) | |
1da177e4 LT |
2370 | { |
2371 | unsigned long uaddr; | |
1da177e4 | 2372 | struct bio *bio; |
dd1cab95 | 2373 | int reading; |
1da177e4 | 2374 | |
defd94b7 | 2375 | if (len > (q->max_hw_sectors << 9)) |
dd1cab95 JA |
2376 | return -EINVAL; |
2377 | if (!len || !ubuf) | |
2378 | return -EINVAL; | |
1da177e4 | 2379 | |
dd1cab95 | 2380 | reading = rq_data_dir(rq) == READ; |
1da177e4 LT |
2381 | |
2382 | /* | |
2383 | * if alignment requirement is satisfied, map in user pages for | |
2384 | * direct dma. else, set up kernel bounce buffers | |
2385 | */ | |
2386 | uaddr = (unsigned long) ubuf; | |
2387 | if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q))) | |
dd1cab95 | 2388 | bio = bio_map_user(q, NULL, uaddr, len, reading); |
1da177e4 | 2389 | else |
dd1cab95 | 2390 | bio = bio_copy_user(q, uaddr, len, reading); |
1da177e4 LT |
2391 | |
2392 | if (!IS_ERR(bio)) { | |
2393 | rq->bio = rq->biotail = bio; | |
2394 | blk_rq_bio_prep(q, rq, bio); | |
2395 | ||
2396 | rq->buffer = rq->data = NULL; | |
2397 | rq->data_len = len; | |
dd1cab95 | 2398 | return 0; |
1da177e4 LT |
2399 | } |
2400 | ||
2401 | /* | |
2402 | * bio is the err-ptr | |
2403 | */ | |
dd1cab95 | 2404 | return PTR_ERR(bio); |
1da177e4 LT |
2405 | } |
2406 | ||
2407 | EXPORT_SYMBOL(blk_rq_map_user); | |
2408 | ||
f1970baf JB |
2409 | /** |
2410 | * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage | |
2411 | * @q: request queue where request should be inserted | |
2412 | * @rq: request to map data to | |
2413 | * @iov: pointer to the iovec | |
2414 | * @iov_count: number of elements in the iovec | |
2415 | * | |
2416 | * Description: | |
2417 | * Data will be mapped directly for zero copy io, if possible. Otherwise | |
2418 | * a kernel bounce buffer is used. | |
2419 | * | |
2420 | * A matching blk_rq_unmap_user() must be issued at the end of io, while | |
2421 | * still in process context. | |
2422 | * | |
2423 | * Note: The mapped bio may need to be bounced through blk_queue_bounce() | |
2424 | * before being submitted to the device, as pages mapped may be out of | |
2425 | * reach. It's the callers responsibility to make sure this happens. The | |
2426 | * original bio must be passed back in to blk_rq_unmap_user() for proper | |
2427 | * unmapping. | |
2428 | */ | |
2429 | int blk_rq_map_user_iov(request_queue_t *q, struct request *rq, | |
2430 | struct sg_iovec *iov, int iov_count) | |
2431 | { | |
2432 | struct bio *bio; | |
2433 | ||
2434 | if (!iov || iov_count <= 0) | |
2435 | return -EINVAL; | |
2436 | ||
2437 | /* we don't allow misaligned data like bio_map_user() does. If the | |
2438 | * user is using sg, they're expected to know the alignment constraints | |
2439 | * and respect them accordingly */ | |
2440 | bio = bio_map_user_iov(q, NULL, iov, iov_count, rq_data_dir(rq)== READ); | |
2441 | if (IS_ERR(bio)) | |
2442 | return PTR_ERR(bio); | |
2443 | ||
2444 | rq->bio = rq->biotail = bio; | |
2445 | blk_rq_bio_prep(q, rq, bio); | |
2446 | rq->buffer = rq->data = NULL; | |
2447 | rq->data_len = bio->bi_size; | |
2448 | return 0; | |
2449 | } | |
2450 | ||
2451 | EXPORT_SYMBOL(blk_rq_map_user_iov); | |
2452 | ||
1da177e4 LT |
2453 | /** |
2454 | * blk_rq_unmap_user - unmap a request with user data | |
73747aed | 2455 | * @bio: bio to be unmapped |
1da177e4 LT |
2456 | * @ulen: length of user buffer |
2457 | * | |
2458 | * Description: | |
73747aed | 2459 | * Unmap a bio previously mapped by blk_rq_map_user(). |
1da177e4 | 2460 | */ |
dd1cab95 | 2461 | int blk_rq_unmap_user(struct bio *bio, unsigned int ulen) |
1da177e4 LT |
2462 | { |
2463 | int ret = 0; | |
2464 | ||
2465 | if (bio) { | |
2466 | if (bio_flagged(bio, BIO_USER_MAPPED)) | |
2467 | bio_unmap_user(bio); | |
2468 | else | |
2469 | ret = bio_uncopy_user(bio); | |
2470 | } | |
2471 | ||
dd1cab95 | 2472 | return 0; |
1da177e4 LT |
2473 | } |
2474 | ||
2475 | EXPORT_SYMBOL(blk_rq_unmap_user); | |
2476 | ||
df46b9a4 MC |
2477 | /** |
2478 | * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage | |
2479 | * @q: request queue where request should be inserted | |
73747aed | 2480 | * @rq: request to fill |
df46b9a4 MC |
2481 | * @kbuf: the kernel buffer |
2482 | * @len: length of user data | |
73747aed | 2483 | * @gfp_mask: memory allocation flags |
df46b9a4 | 2484 | */ |
dd1cab95 | 2485 | int blk_rq_map_kern(request_queue_t *q, struct request *rq, void *kbuf, |
8267e268 | 2486 | unsigned int len, gfp_t gfp_mask) |
df46b9a4 | 2487 | { |
df46b9a4 MC |
2488 | struct bio *bio; |
2489 | ||
defd94b7 | 2490 | if (len > (q->max_hw_sectors << 9)) |
dd1cab95 JA |
2491 | return -EINVAL; |
2492 | if (!len || !kbuf) | |
2493 | return -EINVAL; | |
df46b9a4 MC |
2494 | |
2495 | bio = bio_map_kern(q, kbuf, len, gfp_mask); | |
dd1cab95 JA |
2496 | if (IS_ERR(bio)) |
2497 | return PTR_ERR(bio); | |
df46b9a4 | 2498 | |
dd1cab95 JA |
2499 | if (rq_data_dir(rq) == WRITE) |
2500 | bio->bi_rw |= (1 << BIO_RW); | |
df46b9a4 | 2501 | |
dd1cab95 JA |
2502 | rq->bio = rq->biotail = bio; |
2503 | blk_rq_bio_prep(q, rq, bio); | |
df46b9a4 | 2504 | |
dd1cab95 JA |
2505 | rq->buffer = rq->data = NULL; |
2506 | rq->data_len = len; | |
2507 | return 0; | |
df46b9a4 MC |
2508 | } |
2509 | ||
2510 | EXPORT_SYMBOL(blk_rq_map_kern); | |
2511 | ||
73747aed CH |
2512 | /** |
2513 | * blk_execute_rq_nowait - insert a request into queue for execution | |
2514 | * @q: queue to insert the request in | |
2515 | * @bd_disk: matching gendisk | |
2516 | * @rq: request to insert | |
2517 | * @at_head: insert request at head or tail of queue | |
2518 | * @done: I/O completion handler | |
2519 | * | |
2520 | * Description: | |
2521 | * Insert a fully prepared request at the back of the io scheduler queue | |
2522 | * for execution. Don't wait for completion. | |
2523 | */ | |
f1970baf JB |
2524 | void blk_execute_rq_nowait(request_queue_t *q, struct gendisk *bd_disk, |
2525 | struct request *rq, int at_head, | |
8ffdc655 | 2526 | rq_end_io_fn *done) |
f1970baf JB |
2527 | { |
2528 | int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; | |
2529 | ||
2530 | rq->rq_disk = bd_disk; | |
4aff5e23 | 2531 | rq->cmd_flags |= REQ_NOMERGE; |
f1970baf | 2532 | rq->end_io = done; |
4c5d0bbd AM |
2533 | WARN_ON(irqs_disabled()); |
2534 | spin_lock_irq(q->queue_lock); | |
2535 | __elv_add_request(q, rq, where, 1); | |
2536 | __generic_unplug_device(q); | |
2537 | spin_unlock_irq(q->queue_lock); | |
f1970baf | 2538 | } |
6e39b69e MC |
2539 | EXPORT_SYMBOL_GPL(blk_execute_rq_nowait); |
2540 | ||
1da177e4 LT |
2541 | /** |
2542 | * blk_execute_rq - insert a request into queue for execution | |
2543 | * @q: queue to insert the request in | |
2544 | * @bd_disk: matching gendisk | |
2545 | * @rq: request to insert | |
994ca9a1 | 2546 | * @at_head: insert request at head or tail of queue |
1da177e4 LT |
2547 | * |
2548 | * Description: | |
2549 | * Insert a fully prepared request at the back of the io scheduler queue | |
73747aed | 2550 | * for execution and wait for completion. |
1da177e4 LT |
2551 | */ |
2552 | int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk, | |
994ca9a1 | 2553 | struct request *rq, int at_head) |
1da177e4 | 2554 | { |
60be6b9a | 2555 | DECLARE_COMPLETION_ONSTACK(wait); |
1da177e4 LT |
2556 | char sense[SCSI_SENSE_BUFFERSIZE]; |
2557 | int err = 0; | |
2558 | ||
1da177e4 LT |
2559 | /* |
2560 | * we need an extra reference to the request, so we can look at | |
2561 | * it after io completion | |
2562 | */ | |
2563 | rq->ref_count++; | |
2564 | ||
2565 | if (!rq->sense) { | |
2566 | memset(sense, 0, sizeof(sense)); | |
2567 | rq->sense = sense; | |
2568 | rq->sense_len = 0; | |
2569 | } | |
2570 | ||
1da177e4 | 2571 | rq->waiting = &wait; |
994ca9a1 | 2572 | blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq); |
1da177e4 LT |
2573 | wait_for_completion(&wait); |
2574 | rq->waiting = NULL; | |
2575 | ||
2576 | if (rq->errors) | |
2577 | err = -EIO; | |
2578 | ||
2579 | return err; | |
2580 | } | |
2581 | ||
2582 | EXPORT_SYMBOL(blk_execute_rq); | |
2583 | ||
2584 | /** | |
2585 | * blkdev_issue_flush - queue a flush | |
2586 | * @bdev: blockdev to issue flush for | |
2587 | * @error_sector: error sector | |
2588 | * | |
2589 | * Description: | |
2590 | * Issue a flush for the block device in question. Caller can supply | |
2591 | * room for storing the error offset in case of a flush error, if they | |
2592 | * wish to. Caller must run wait_for_completion() on its own. | |
2593 | */ | |
2594 | int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector) | |
2595 | { | |
2596 | request_queue_t *q; | |
2597 | ||
2598 | if (bdev->bd_disk == NULL) | |
2599 | return -ENXIO; | |
2600 | ||
2601 | q = bdev_get_queue(bdev); | |
2602 | if (!q) | |
2603 | return -ENXIO; | |
2604 | if (!q->issue_flush_fn) | |
2605 | return -EOPNOTSUPP; | |
2606 | ||
2607 | return q->issue_flush_fn(q, bdev->bd_disk, error_sector); | |
2608 | } | |
2609 | ||
2610 | EXPORT_SYMBOL(blkdev_issue_flush); | |
2611 | ||
93d17d3d | 2612 | static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io) |
1da177e4 LT |
2613 | { |
2614 | int rw = rq_data_dir(rq); | |
2615 | ||
2616 | if (!blk_fs_request(rq) || !rq->rq_disk) | |
2617 | return; | |
2618 | ||
d72d904a | 2619 | if (!new_io) { |
a362357b | 2620 | __disk_stat_inc(rq->rq_disk, merges[rw]); |
d72d904a | 2621 | } else { |
1da177e4 LT |
2622 | disk_round_stats(rq->rq_disk); |
2623 | rq->rq_disk->in_flight++; | |
2624 | } | |
2625 | } | |
2626 | ||
2627 | /* | |
2628 | * add-request adds a request to the linked list. | |
2629 | * queue lock is held and interrupts disabled, as we muck with the | |
2630 | * request queue list. | |
2631 | */ | |
2632 | static inline void add_request(request_queue_t * q, struct request * req) | |
2633 | { | |
2634 | drive_stat_acct(req, req->nr_sectors, 1); | |
2635 | ||
2636 | if (q->activity_fn) | |
2637 | q->activity_fn(q->activity_data, rq_data_dir(req)); | |
2638 | ||
2639 | /* | |
2640 | * elevator indicated where it wants this request to be | |
2641 | * inserted at elevator_merge time | |
2642 | */ | |
2643 | __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0); | |
2644 | } | |
2645 | ||
2646 | /* | |
2647 | * disk_round_stats() - Round off the performance stats on a struct | |
2648 | * disk_stats. | |
2649 | * | |
2650 | * The average IO queue length and utilisation statistics are maintained | |
2651 | * by observing the current state of the queue length and the amount of | |
2652 | * time it has been in this state for. | |
2653 | * | |
2654 | * Normally, that accounting is done on IO completion, but that can result | |
2655 | * in more than a second's worth of IO being accounted for within any one | |
2656 | * second, leading to >100% utilisation. To deal with that, we call this | |
2657 | * function to do a round-off before returning the results when reading | |
2658 | * /proc/diskstats. This accounts immediately for all queue usage up to | |
2659 | * the current jiffies and restarts the counters again. | |
2660 | */ | |
2661 | void disk_round_stats(struct gendisk *disk) | |
2662 | { | |
2663 | unsigned long now = jiffies; | |
2664 | ||
b2982649 KC |
2665 | if (now == disk->stamp) |
2666 | return; | |
1da177e4 | 2667 | |
20e5c81f KC |
2668 | if (disk->in_flight) { |
2669 | __disk_stat_add(disk, time_in_queue, | |
2670 | disk->in_flight * (now - disk->stamp)); | |
2671 | __disk_stat_add(disk, io_ticks, (now - disk->stamp)); | |
2672 | } | |
1da177e4 | 2673 | disk->stamp = now; |
1da177e4 LT |
2674 | } |
2675 | ||
3eaf840e JNN |
2676 | EXPORT_SYMBOL_GPL(disk_round_stats); |
2677 | ||
1da177e4 LT |
2678 | /* |
2679 | * queue lock must be held | |
2680 | */ | |
6e39b69e | 2681 | void __blk_put_request(request_queue_t *q, struct request *req) |
1da177e4 LT |
2682 | { |
2683 | struct request_list *rl = req->rl; | |
2684 | ||
2685 | if (unlikely(!q)) | |
2686 | return; | |
2687 | if (unlikely(--req->ref_count)) | |
2688 | return; | |
2689 | ||
8922e16c TH |
2690 | elv_completed_request(q, req); |
2691 | ||
1da177e4 | 2692 | req->rq_status = RQ_INACTIVE; |
1da177e4 LT |
2693 | req->rl = NULL; |
2694 | ||
2695 | /* | |
2696 | * Request may not have originated from ll_rw_blk. if not, | |
2697 | * it didn't come out of our reserved rq pools | |
2698 | */ | |
2699 | if (rl) { | |
2700 | int rw = rq_data_dir(req); | |
4aff5e23 | 2701 | int priv = req->cmd_flags & REQ_ELVPRIV; |
1da177e4 | 2702 | |
1da177e4 | 2703 | BUG_ON(!list_empty(&req->queuelist)); |
9817064b | 2704 | BUG_ON(!hlist_unhashed(&req->hash)); |
1da177e4 LT |
2705 | |
2706 | blk_free_request(q, req); | |
cb98fc8b | 2707 | freed_request(q, rw, priv); |
1da177e4 LT |
2708 | } |
2709 | } | |
2710 | ||
6e39b69e MC |
2711 | EXPORT_SYMBOL_GPL(__blk_put_request); |
2712 | ||
1da177e4 LT |
2713 | void blk_put_request(struct request *req) |
2714 | { | |
8922e16c TH |
2715 | unsigned long flags; |
2716 | request_queue_t *q = req->q; | |
2717 | ||
1da177e4 | 2718 | /* |
8922e16c TH |
2719 | * Gee, IDE calls in w/ NULL q. Fix IDE and remove the |
2720 | * following if (q) test. | |
1da177e4 | 2721 | */ |
8922e16c | 2722 | if (q) { |
1da177e4 LT |
2723 | spin_lock_irqsave(q->queue_lock, flags); |
2724 | __blk_put_request(q, req); | |
2725 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2726 | } | |
2727 | } | |
2728 | ||
2729 | EXPORT_SYMBOL(blk_put_request); | |
2730 | ||
2731 | /** | |
2732 | * blk_end_sync_rq - executes a completion event on a request | |
2733 | * @rq: request to complete | |
fddfdeaf | 2734 | * @error: end io status of the request |
1da177e4 | 2735 | */ |
8ffdc655 | 2736 | void blk_end_sync_rq(struct request *rq, int error) |
1da177e4 LT |
2737 | { |
2738 | struct completion *waiting = rq->waiting; | |
2739 | ||
2740 | rq->waiting = NULL; | |
2741 | __blk_put_request(rq->q, rq); | |
2742 | ||
2743 | /* | |
2744 | * complete last, if this is a stack request the process (and thus | |
2745 | * the rq pointer) could be invalid right after this complete() | |
2746 | */ | |
2747 | complete(waiting); | |
2748 | } | |
2749 | EXPORT_SYMBOL(blk_end_sync_rq); | |
2750 | ||
2751 | /** | |
2752 | * blk_congestion_wait - wait for a queue to become uncongested | |
2753 | * @rw: READ or WRITE | |
2754 | * @timeout: timeout in jiffies | |
2755 | * | |
2756 | * Waits for up to @timeout jiffies for a queue (any queue) to exit congestion. | |
2757 | * If no queues are congested then just wait for the next request to be | |
2758 | * returned. | |
2759 | */ | |
2760 | long blk_congestion_wait(int rw, long timeout) | |
2761 | { | |
2762 | long ret; | |
2763 | DEFINE_WAIT(wait); | |
2764 | wait_queue_head_t *wqh = &congestion_wqh[rw]; | |
2765 | ||
2766 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
2767 | ret = io_schedule_timeout(timeout); | |
2768 | finish_wait(wqh, &wait); | |
2769 | return ret; | |
2770 | } | |
2771 | ||
2772 | EXPORT_SYMBOL(blk_congestion_wait); | |
2773 | ||
275a082f TM |
2774 | /** |
2775 | * blk_congestion_end - wake up sleepers on a congestion queue | |
2776 | * @rw: READ or WRITE | |
2777 | */ | |
2778 | void blk_congestion_end(int rw) | |
2779 | { | |
2780 | wait_queue_head_t *wqh = &congestion_wqh[rw]; | |
2781 | ||
2782 | if (waitqueue_active(wqh)) | |
2783 | wake_up(wqh); | |
2784 | } | |
2785 | ||
1da177e4 LT |
2786 | /* |
2787 | * Has to be called with the request spinlock acquired | |
2788 | */ | |
2789 | static int attempt_merge(request_queue_t *q, struct request *req, | |
2790 | struct request *next) | |
2791 | { | |
2792 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
2793 | return 0; | |
2794 | ||
2795 | /* | |
d6e05edc | 2796 | * not contiguous |
1da177e4 LT |
2797 | */ |
2798 | if (req->sector + req->nr_sectors != next->sector) | |
2799 | return 0; | |
2800 | ||
2801 | if (rq_data_dir(req) != rq_data_dir(next) | |
2802 | || req->rq_disk != next->rq_disk | |
2803 | || next->waiting || next->special) | |
2804 | return 0; | |
2805 | ||
2806 | /* | |
2807 | * If we are allowed to merge, then append bio list | |
2808 | * from next to rq and release next. merge_requests_fn | |
2809 | * will have updated segment counts, update sector | |
2810 | * counts here. | |
2811 | */ | |
2812 | if (!q->merge_requests_fn(q, req, next)) | |
2813 | return 0; | |
2814 | ||
2815 | /* | |
2816 | * At this point we have either done a back merge | |
2817 | * or front merge. We need the smaller start_time of | |
2818 | * the merged requests to be the current request | |
2819 | * for accounting purposes. | |
2820 | */ | |
2821 | if (time_after(req->start_time, next->start_time)) | |
2822 | req->start_time = next->start_time; | |
2823 | ||
2824 | req->biotail->bi_next = next->bio; | |
2825 | req->biotail = next->biotail; | |
2826 | ||
2827 | req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors; | |
2828 | ||
2829 | elv_merge_requests(q, req, next); | |
2830 | ||
2831 | if (req->rq_disk) { | |
2832 | disk_round_stats(req->rq_disk); | |
2833 | req->rq_disk->in_flight--; | |
2834 | } | |
2835 | ||
22e2c507 JA |
2836 | req->ioprio = ioprio_best(req->ioprio, next->ioprio); |
2837 | ||
1da177e4 LT |
2838 | __blk_put_request(q, next); |
2839 | return 1; | |
2840 | } | |
2841 | ||
2842 | static inline int attempt_back_merge(request_queue_t *q, struct request *rq) | |
2843 | { | |
2844 | struct request *next = elv_latter_request(q, rq); | |
2845 | ||
2846 | if (next) | |
2847 | return attempt_merge(q, rq, next); | |
2848 | ||
2849 | return 0; | |
2850 | } | |
2851 | ||
2852 | static inline int attempt_front_merge(request_queue_t *q, struct request *rq) | |
2853 | { | |
2854 | struct request *prev = elv_former_request(q, rq); | |
2855 | ||
2856 | if (prev) | |
2857 | return attempt_merge(q, prev, rq); | |
2858 | ||
2859 | return 0; | |
2860 | } | |
2861 | ||
52d9e675 TH |
2862 | static void init_request_from_bio(struct request *req, struct bio *bio) |
2863 | { | |
4aff5e23 | 2864 | req->cmd_type = REQ_TYPE_FS; |
52d9e675 TH |
2865 | |
2866 | /* | |
2867 | * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST) | |
2868 | */ | |
2869 | if (bio_rw_ahead(bio) || bio_failfast(bio)) | |
4aff5e23 | 2870 | req->cmd_flags |= REQ_FAILFAST; |
52d9e675 TH |
2871 | |
2872 | /* | |
2873 | * REQ_BARRIER implies no merging, but lets make it explicit | |
2874 | */ | |
2875 | if (unlikely(bio_barrier(bio))) | |
4aff5e23 | 2876 | req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE); |
52d9e675 | 2877 | |
b31dc66a | 2878 | if (bio_sync(bio)) |
4aff5e23 | 2879 | req->cmd_flags |= REQ_RW_SYNC; |
b31dc66a | 2880 | |
52d9e675 TH |
2881 | req->errors = 0; |
2882 | req->hard_sector = req->sector = bio->bi_sector; | |
2883 | req->hard_nr_sectors = req->nr_sectors = bio_sectors(bio); | |
2884 | req->current_nr_sectors = req->hard_cur_sectors = bio_cur_sectors(bio); | |
2885 | req->nr_phys_segments = bio_phys_segments(req->q, bio); | |
2886 | req->nr_hw_segments = bio_hw_segments(req->q, bio); | |
2887 | req->buffer = bio_data(bio); /* see ->buffer comment above */ | |
2888 | req->waiting = NULL; | |
2889 | req->bio = req->biotail = bio; | |
2890 | req->ioprio = bio_prio(bio); | |
2891 | req->rq_disk = bio->bi_bdev->bd_disk; | |
2892 | req->start_time = jiffies; | |
2893 | } | |
2894 | ||
1da177e4 LT |
2895 | static int __make_request(request_queue_t *q, struct bio *bio) |
2896 | { | |
450991bc | 2897 | struct request *req; |
4a534f93 | 2898 | int el_ret, rw, nr_sectors, cur_nr_sectors, barrier, err, sync; |
22e2c507 | 2899 | unsigned short prio; |
1da177e4 LT |
2900 | sector_t sector; |
2901 | ||
2902 | sector = bio->bi_sector; | |
2903 | nr_sectors = bio_sectors(bio); | |
2904 | cur_nr_sectors = bio_cur_sectors(bio); | |
22e2c507 | 2905 | prio = bio_prio(bio); |
1da177e4 LT |
2906 | |
2907 | rw = bio_data_dir(bio); | |
4a534f93 | 2908 | sync = bio_sync(bio); |
1da177e4 LT |
2909 | |
2910 | /* | |
2911 | * low level driver can indicate that it wants pages above a | |
2912 | * certain limit bounced to low memory (ie for highmem, or even | |
2913 | * ISA dma in theory) | |
2914 | */ | |
2915 | blk_queue_bounce(q, &bio); | |
2916 | ||
2917 | spin_lock_prefetch(q->queue_lock); | |
2918 | ||
2919 | barrier = bio_barrier(bio); | |
797e7dbb | 2920 | if (unlikely(barrier) && (q->next_ordered == QUEUE_ORDERED_NONE)) { |
1da177e4 LT |
2921 | err = -EOPNOTSUPP; |
2922 | goto end_io; | |
2923 | } | |
2924 | ||
1da177e4 LT |
2925 | spin_lock_irq(q->queue_lock); |
2926 | ||
450991bc | 2927 | if (unlikely(barrier) || elv_queue_empty(q)) |
1da177e4 LT |
2928 | goto get_rq; |
2929 | ||
2930 | el_ret = elv_merge(q, &req, bio); | |
2931 | switch (el_ret) { | |
2932 | case ELEVATOR_BACK_MERGE: | |
2933 | BUG_ON(!rq_mergeable(req)); | |
2934 | ||
2935 | if (!q->back_merge_fn(q, req, bio)) | |
2936 | break; | |
2937 | ||
2056a782 JA |
2938 | blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE); |
2939 | ||
1da177e4 LT |
2940 | req->biotail->bi_next = bio; |
2941 | req->biotail = bio; | |
2942 | req->nr_sectors = req->hard_nr_sectors += nr_sectors; | |
22e2c507 | 2943 | req->ioprio = ioprio_best(req->ioprio, prio); |
1da177e4 LT |
2944 | drive_stat_acct(req, nr_sectors, 0); |
2945 | if (!attempt_back_merge(q, req)) | |
2946 | elv_merged_request(q, req); | |
2947 | goto out; | |
2948 | ||
2949 | case ELEVATOR_FRONT_MERGE: | |
2950 | BUG_ON(!rq_mergeable(req)); | |
2951 | ||
2952 | if (!q->front_merge_fn(q, req, bio)) | |
2953 | break; | |
2954 | ||
2056a782 JA |
2955 | blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE); |
2956 | ||
1da177e4 LT |
2957 | bio->bi_next = req->bio; |
2958 | req->bio = bio; | |
2959 | ||
2960 | /* | |
2961 | * may not be valid. if the low level driver said | |
2962 | * it didn't need a bounce buffer then it better | |
2963 | * not touch req->buffer either... | |
2964 | */ | |
2965 | req->buffer = bio_data(bio); | |
2966 | req->current_nr_sectors = cur_nr_sectors; | |
2967 | req->hard_cur_sectors = cur_nr_sectors; | |
2968 | req->sector = req->hard_sector = sector; | |
2969 | req->nr_sectors = req->hard_nr_sectors += nr_sectors; | |
22e2c507 | 2970 | req->ioprio = ioprio_best(req->ioprio, prio); |
1da177e4 LT |
2971 | drive_stat_acct(req, nr_sectors, 0); |
2972 | if (!attempt_front_merge(q, req)) | |
2973 | elv_merged_request(q, req); | |
2974 | goto out; | |
2975 | ||
450991bc | 2976 | /* ELV_NO_MERGE: elevator says don't/can't merge. */ |
1da177e4 | 2977 | default: |
450991bc | 2978 | ; |
1da177e4 LT |
2979 | } |
2980 | ||
450991bc | 2981 | get_rq: |
1da177e4 | 2982 | /* |
450991bc | 2983 | * Grab a free request. This is might sleep but can not fail. |
d6344532 | 2984 | * Returns with the queue unlocked. |
450991bc | 2985 | */ |
450991bc | 2986 | req = get_request_wait(q, rw, bio); |
d6344532 | 2987 | |
450991bc NP |
2988 | /* |
2989 | * After dropping the lock and possibly sleeping here, our request | |
2990 | * may now be mergeable after it had proven unmergeable (above). | |
2991 | * We don't worry about that case for efficiency. It won't happen | |
2992 | * often, and the elevators are able to handle it. | |
1da177e4 | 2993 | */ |
52d9e675 | 2994 | init_request_from_bio(req, bio); |
1da177e4 | 2995 | |
450991bc NP |
2996 | spin_lock_irq(q->queue_lock); |
2997 | if (elv_queue_empty(q)) | |
2998 | blk_plug_device(q); | |
1da177e4 LT |
2999 | add_request(q, req); |
3000 | out: | |
4a534f93 | 3001 | if (sync) |
1da177e4 LT |
3002 | __generic_unplug_device(q); |
3003 | ||
3004 | spin_unlock_irq(q->queue_lock); | |
3005 | return 0; | |
3006 | ||
3007 | end_io: | |
3008 | bio_endio(bio, nr_sectors << 9, err); | |
3009 | return 0; | |
3010 | } | |
3011 | ||
3012 | /* | |
3013 | * If bio->bi_dev is a partition, remap the location | |
3014 | */ | |
3015 | static inline void blk_partition_remap(struct bio *bio) | |
3016 | { | |
3017 | struct block_device *bdev = bio->bi_bdev; | |
3018 | ||
3019 | if (bdev != bdev->bd_contains) { | |
3020 | struct hd_struct *p = bdev->bd_part; | |
a362357b JA |
3021 | const int rw = bio_data_dir(bio); |
3022 | ||
3023 | p->sectors[rw] += bio_sectors(bio); | |
3024 | p->ios[rw]++; | |
1da177e4 | 3025 | |
1da177e4 LT |
3026 | bio->bi_sector += p->start_sect; |
3027 | bio->bi_bdev = bdev->bd_contains; | |
3028 | } | |
3029 | } | |
3030 | ||
1da177e4 LT |
3031 | static void handle_bad_sector(struct bio *bio) |
3032 | { | |
3033 | char b[BDEVNAME_SIZE]; | |
3034 | ||
3035 | printk(KERN_INFO "attempt to access beyond end of device\n"); | |
3036 | printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", | |
3037 | bdevname(bio->bi_bdev, b), | |
3038 | bio->bi_rw, | |
3039 | (unsigned long long)bio->bi_sector + bio_sectors(bio), | |
3040 | (long long)(bio->bi_bdev->bd_inode->i_size >> 9)); | |
3041 | ||
3042 | set_bit(BIO_EOF, &bio->bi_flags); | |
3043 | } | |
3044 | ||
3045 | /** | |
3046 | * generic_make_request: hand a buffer to its device driver for I/O | |
3047 | * @bio: The bio describing the location in memory and on the device. | |
3048 | * | |
3049 | * generic_make_request() is used to make I/O requests of block | |
3050 | * devices. It is passed a &struct bio, which describes the I/O that needs | |
3051 | * to be done. | |
3052 | * | |
3053 | * generic_make_request() does not return any status. The | |
3054 | * success/failure status of the request, along with notification of | |
3055 | * completion, is delivered asynchronously through the bio->bi_end_io | |
3056 | * function described (one day) else where. | |
3057 | * | |
3058 | * The caller of generic_make_request must make sure that bi_io_vec | |
3059 | * are set to describe the memory buffer, and that bi_dev and bi_sector are | |
3060 | * set to describe the device address, and the | |
3061 | * bi_end_io and optionally bi_private are set to describe how | |
3062 | * completion notification should be signaled. | |
3063 | * | |
3064 | * generic_make_request and the drivers it calls may use bi_next if this | |
3065 | * bio happens to be merged with someone else, and may change bi_dev and | |
3066 | * bi_sector for remaps as it sees fit. So the values of these fields | |
3067 | * should NOT be depended on after the call to generic_make_request. | |
3068 | */ | |
3069 | void generic_make_request(struct bio *bio) | |
3070 | { | |
3071 | request_queue_t *q; | |
3072 | sector_t maxsector; | |
3073 | int ret, nr_sectors = bio_sectors(bio); | |
2056a782 | 3074 | dev_t old_dev; |
1da177e4 LT |
3075 | |
3076 | might_sleep(); | |
3077 | /* Test device or partition size, when known. */ | |
3078 | maxsector = bio->bi_bdev->bd_inode->i_size >> 9; | |
3079 | if (maxsector) { | |
3080 | sector_t sector = bio->bi_sector; | |
3081 | ||
3082 | if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { | |
3083 | /* | |
3084 | * This may well happen - the kernel calls bread() | |
3085 | * without checking the size of the device, e.g., when | |
3086 | * mounting a device. | |
3087 | */ | |
3088 | handle_bad_sector(bio); | |
3089 | goto end_io; | |
3090 | } | |
3091 | } | |
3092 | ||
3093 | /* | |
3094 | * Resolve the mapping until finished. (drivers are | |
3095 | * still free to implement/resolve their own stacking | |
3096 | * by explicitly returning 0) | |
3097 | * | |
3098 | * NOTE: we don't repeat the blk_size check for each new device. | |
3099 | * Stacking drivers are expected to know what they are doing. | |
3100 | */ | |
2056a782 JA |
3101 | maxsector = -1; |
3102 | old_dev = 0; | |
1da177e4 LT |
3103 | do { |
3104 | char b[BDEVNAME_SIZE]; | |
3105 | ||
3106 | q = bdev_get_queue(bio->bi_bdev); | |
3107 | if (!q) { | |
3108 | printk(KERN_ERR | |
3109 | "generic_make_request: Trying to access " | |
3110 | "nonexistent block-device %s (%Lu)\n", | |
3111 | bdevname(bio->bi_bdev, b), | |
3112 | (long long) bio->bi_sector); | |
3113 | end_io: | |
3114 | bio_endio(bio, bio->bi_size, -EIO); | |
3115 | break; | |
3116 | } | |
3117 | ||
3118 | if (unlikely(bio_sectors(bio) > q->max_hw_sectors)) { | |
3119 | printk("bio too big device %s (%u > %u)\n", | |
3120 | bdevname(bio->bi_bdev, b), | |
3121 | bio_sectors(bio), | |
3122 | q->max_hw_sectors); | |
3123 | goto end_io; | |
3124 | } | |
3125 | ||
fde6ad22 | 3126 | if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) |
1da177e4 LT |
3127 | goto end_io; |
3128 | ||
1da177e4 LT |
3129 | /* |
3130 | * If this device has partitions, remap block n | |
3131 | * of partition p to block n+start(p) of the disk. | |
3132 | */ | |
3133 | blk_partition_remap(bio); | |
3134 | ||
2056a782 JA |
3135 | if (maxsector != -1) |
3136 | blk_add_trace_remap(q, bio, old_dev, bio->bi_sector, | |
3137 | maxsector); | |
3138 | ||
3139 | blk_add_trace_bio(q, bio, BLK_TA_QUEUE); | |
3140 | ||
3141 | maxsector = bio->bi_sector; | |
3142 | old_dev = bio->bi_bdev->bd_dev; | |
3143 | ||
1da177e4 LT |
3144 | ret = q->make_request_fn(q, bio); |
3145 | } while (ret); | |
3146 | } | |
3147 | ||
3148 | EXPORT_SYMBOL(generic_make_request); | |
3149 | ||
3150 | /** | |
3151 | * submit_bio: submit a bio to the block device layer for I/O | |
3152 | * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) | |
3153 | * @bio: The &struct bio which describes the I/O | |
3154 | * | |
3155 | * submit_bio() is very similar in purpose to generic_make_request(), and | |
3156 | * uses that function to do most of the work. Both are fairly rough | |
3157 | * interfaces, @bio must be presetup and ready for I/O. | |
3158 | * | |
3159 | */ | |
3160 | void submit_bio(int rw, struct bio *bio) | |
3161 | { | |
3162 | int count = bio_sectors(bio); | |
3163 | ||
3164 | BIO_BUG_ON(!bio->bi_size); | |
3165 | BIO_BUG_ON(!bio->bi_io_vec); | |
22e2c507 | 3166 | bio->bi_rw |= rw; |
1da177e4 | 3167 | if (rw & WRITE) |
f8891e5e | 3168 | count_vm_events(PGPGOUT, count); |
1da177e4 | 3169 | else |
f8891e5e | 3170 | count_vm_events(PGPGIN, count); |
1da177e4 LT |
3171 | |
3172 | if (unlikely(block_dump)) { | |
3173 | char b[BDEVNAME_SIZE]; | |
3174 | printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n", | |
3175 | current->comm, current->pid, | |
3176 | (rw & WRITE) ? "WRITE" : "READ", | |
3177 | (unsigned long long)bio->bi_sector, | |
3178 | bdevname(bio->bi_bdev,b)); | |
3179 | } | |
3180 | ||
3181 | generic_make_request(bio); | |
3182 | } | |
3183 | ||
3184 | EXPORT_SYMBOL(submit_bio); | |
3185 | ||
93d17d3d | 3186 | static void blk_recalc_rq_segments(struct request *rq) |
1da177e4 LT |
3187 | { |
3188 | struct bio *bio, *prevbio = NULL; | |
3189 | int nr_phys_segs, nr_hw_segs; | |
3190 | unsigned int phys_size, hw_size; | |
3191 | request_queue_t *q = rq->q; | |
3192 | ||
3193 | if (!rq->bio) | |
3194 | return; | |
3195 | ||
3196 | phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0; | |
3197 | rq_for_each_bio(bio, rq) { | |
3198 | /* Force bio hw/phys segs to be recalculated. */ | |
3199 | bio->bi_flags &= ~(1 << BIO_SEG_VALID); | |
3200 | ||
3201 | nr_phys_segs += bio_phys_segments(q, bio); | |
3202 | nr_hw_segs += bio_hw_segments(q, bio); | |
3203 | if (prevbio) { | |
3204 | int pseg = phys_size + prevbio->bi_size + bio->bi_size; | |
3205 | int hseg = hw_size + prevbio->bi_size + bio->bi_size; | |
3206 | ||
3207 | if (blk_phys_contig_segment(q, prevbio, bio) && | |
3208 | pseg <= q->max_segment_size) { | |
3209 | nr_phys_segs--; | |
3210 | phys_size += prevbio->bi_size + bio->bi_size; | |
3211 | } else | |
3212 | phys_size = 0; | |
3213 | ||
3214 | if (blk_hw_contig_segment(q, prevbio, bio) && | |
3215 | hseg <= q->max_segment_size) { | |
3216 | nr_hw_segs--; | |
3217 | hw_size += prevbio->bi_size + bio->bi_size; | |
3218 | } else | |
3219 | hw_size = 0; | |
3220 | } | |
3221 | prevbio = bio; | |
3222 | } | |
3223 | ||
3224 | rq->nr_phys_segments = nr_phys_segs; | |
3225 | rq->nr_hw_segments = nr_hw_segs; | |
3226 | } | |
3227 | ||
93d17d3d | 3228 | static void blk_recalc_rq_sectors(struct request *rq, int nsect) |
1da177e4 LT |
3229 | { |
3230 | if (blk_fs_request(rq)) { | |
3231 | rq->hard_sector += nsect; | |
3232 | rq->hard_nr_sectors -= nsect; | |
3233 | ||
3234 | /* | |
3235 | * Move the I/O submission pointers ahead if required. | |
3236 | */ | |
3237 | if ((rq->nr_sectors >= rq->hard_nr_sectors) && | |
3238 | (rq->sector <= rq->hard_sector)) { | |
3239 | rq->sector = rq->hard_sector; | |
3240 | rq->nr_sectors = rq->hard_nr_sectors; | |
3241 | rq->hard_cur_sectors = bio_cur_sectors(rq->bio); | |
3242 | rq->current_nr_sectors = rq->hard_cur_sectors; | |
3243 | rq->buffer = bio_data(rq->bio); | |
3244 | } | |
3245 | ||
3246 | /* | |
3247 | * if total number of sectors is less than the first segment | |
3248 | * size, something has gone terribly wrong | |
3249 | */ | |
3250 | if (rq->nr_sectors < rq->current_nr_sectors) { | |
3251 | printk("blk: request botched\n"); | |
3252 | rq->nr_sectors = rq->current_nr_sectors; | |
3253 | } | |
3254 | } | |
3255 | } | |
3256 | ||
3257 | static int __end_that_request_first(struct request *req, int uptodate, | |
3258 | int nr_bytes) | |
3259 | { | |
3260 | int total_bytes, bio_nbytes, error, next_idx = 0; | |
3261 | struct bio *bio; | |
3262 | ||
2056a782 JA |
3263 | blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE); |
3264 | ||
1da177e4 LT |
3265 | /* |
3266 | * extend uptodate bool to allow < 0 value to be direct io error | |
3267 | */ | |
3268 | error = 0; | |
3269 | if (end_io_error(uptodate)) | |
3270 | error = !uptodate ? -EIO : uptodate; | |
3271 | ||
3272 | /* | |
3273 | * for a REQ_BLOCK_PC request, we want to carry any eventual | |
3274 | * sense key with us all the way through | |
3275 | */ | |
3276 | if (!blk_pc_request(req)) | |
3277 | req->errors = 0; | |
3278 | ||
3279 | if (!uptodate) { | |
4aff5e23 | 3280 | if (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET)) |
1da177e4 LT |
3281 | printk("end_request: I/O error, dev %s, sector %llu\n", |
3282 | req->rq_disk ? req->rq_disk->disk_name : "?", | |
3283 | (unsigned long long)req->sector); | |
3284 | } | |
3285 | ||
d72d904a | 3286 | if (blk_fs_request(req) && req->rq_disk) { |
a362357b JA |
3287 | const int rw = rq_data_dir(req); |
3288 | ||
53e86061 | 3289 | disk_stat_add(req->rq_disk, sectors[rw], nr_bytes >> 9); |
d72d904a JA |
3290 | } |
3291 | ||
1da177e4 LT |
3292 | total_bytes = bio_nbytes = 0; |
3293 | while ((bio = req->bio) != NULL) { | |
3294 | int nbytes; | |
3295 | ||
3296 | if (nr_bytes >= bio->bi_size) { | |
3297 | req->bio = bio->bi_next; | |
3298 | nbytes = bio->bi_size; | |
797e7dbb TH |
3299 | if (!ordered_bio_endio(req, bio, nbytes, error)) |
3300 | bio_endio(bio, nbytes, error); | |
1da177e4 LT |
3301 | next_idx = 0; |
3302 | bio_nbytes = 0; | |
3303 | } else { | |
3304 | int idx = bio->bi_idx + next_idx; | |
3305 | ||
3306 | if (unlikely(bio->bi_idx >= bio->bi_vcnt)) { | |
3307 | blk_dump_rq_flags(req, "__end_that"); | |
3308 | printk("%s: bio idx %d >= vcnt %d\n", | |
3309 | __FUNCTION__, | |
3310 | bio->bi_idx, bio->bi_vcnt); | |
3311 | break; | |
3312 | } | |
3313 | ||
3314 | nbytes = bio_iovec_idx(bio, idx)->bv_len; | |
3315 | BIO_BUG_ON(nbytes > bio->bi_size); | |
3316 | ||
3317 | /* | |
3318 | * not a complete bvec done | |
3319 | */ | |
3320 | if (unlikely(nbytes > nr_bytes)) { | |
3321 | bio_nbytes += nr_bytes; | |
3322 | total_bytes += nr_bytes; | |
3323 | break; | |
3324 | } | |
3325 | ||
3326 | /* | |
3327 | * advance to the next vector | |
3328 | */ | |
3329 | next_idx++; | |
3330 | bio_nbytes += nbytes; | |
3331 | } | |
3332 | ||
3333 | total_bytes += nbytes; | |
3334 | nr_bytes -= nbytes; | |
3335 | ||
3336 | if ((bio = req->bio)) { | |
3337 | /* | |
3338 | * end more in this run, or just return 'not-done' | |
3339 | */ | |
3340 | if (unlikely(nr_bytes <= 0)) | |
3341 | break; | |
3342 | } | |
3343 | } | |
3344 | ||
3345 | /* | |
3346 | * completely done | |
3347 | */ | |
3348 | if (!req->bio) | |
3349 | return 0; | |
3350 | ||
3351 | /* | |
3352 | * if the request wasn't completed, update state | |
3353 | */ | |
3354 | if (bio_nbytes) { | |
797e7dbb TH |
3355 | if (!ordered_bio_endio(req, bio, bio_nbytes, error)) |
3356 | bio_endio(bio, bio_nbytes, error); | |
1da177e4 LT |
3357 | bio->bi_idx += next_idx; |
3358 | bio_iovec(bio)->bv_offset += nr_bytes; | |
3359 | bio_iovec(bio)->bv_len -= nr_bytes; | |
3360 | } | |
3361 | ||
3362 | blk_recalc_rq_sectors(req, total_bytes >> 9); | |
3363 | blk_recalc_rq_segments(req); | |
3364 | return 1; | |
3365 | } | |
3366 | ||
3367 | /** | |
3368 | * end_that_request_first - end I/O on a request | |
3369 | * @req: the request being processed | |
3370 | * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error | |
3371 | * @nr_sectors: number of sectors to end I/O on | |
3372 | * | |
3373 | * Description: | |
3374 | * Ends I/O on a number of sectors attached to @req, and sets it up | |
3375 | * for the next range of segments (if any) in the cluster. | |
3376 | * | |
3377 | * Return: | |
3378 | * 0 - we are done with this request, call end_that_request_last() | |
3379 | * 1 - still buffers pending for this request | |
3380 | **/ | |
3381 | int end_that_request_first(struct request *req, int uptodate, int nr_sectors) | |
3382 | { | |
3383 | return __end_that_request_first(req, uptodate, nr_sectors << 9); | |
3384 | } | |
3385 | ||
3386 | EXPORT_SYMBOL(end_that_request_first); | |
3387 | ||
3388 | /** | |
3389 | * end_that_request_chunk - end I/O on a request | |
3390 | * @req: the request being processed | |
3391 | * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error | |
3392 | * @nr_bytes: number of bytes to complete | |
3393 | * | |
3394 | * Description: | |
3395 | * Ends I/O on a number of bytes attached to @req, and sets it up | |
3396 | * for the next range of segments (if any). Like end_that_request_first(), | |
3397 | * but deals with bytes instead of sectors. | |
3398 | * | |
3399 | * Return: | |
3400 | * 0 - we are done with this request, call end_that_request_last() | |
3401 | * 1 - still buffers pending for this request | |
3402 | **/ | |
3403 | int end_that_request_chunk(struct request *req, int uptodate, int nr_bytes) | |
3404 | { | |
3405 | return __end_that_request_first(req, uptodate, nr_bytes); | |
3406 | } | |
3407 | ||
3408 | EXPORT_SYMBOL(end_that_request_chunk); | |
3409 | ||
ff856bad JA |
3410 | /* |
3411 | * splice the completion data to a local structure and hand off to | |
3412 | * process_completion_queue() to complete the requests | |
3413 | */ | |
3414 | static void blk_done_softirq(struct softirq_action *h) | |
3415 | { | |
626ab0e6 | 3416 | struct list_head *cpu_list, local_list; |
ff856bad JA |
3417 | |
3418 | local_irq_disable(); | |
3419 | cpu_list = &__get_cpu_var(blk_cpu_done); | |
626ab0e6 | 3420 | list_replace_init(cpu_list, &local_list); |
ff856bad JA |
3421 | local_irq_enable(); |
3422 | ||
3423 | while (!list_empty(&local_list)) { | |
3424 | struct request *rq = list_entry(local_list.next, struct request, donelist); | |
3425 | ||
3426 | list_del_init(&rq->donelist); | |
3427 | rq->q->softirq_done_fn(rq); | |
3428 | } | |
3429 | } | |
3430 | ||
3431 | #ifdef CONFIG_HOTPLUG_CPU | |
3432 | ||
3433 | static int blk_cpu_notify(struct notifier_block *self, unsigned long action, | |
3434 | void *hcpu) | |
3435 | { | |
3436 | /* | |
3437 | * If a CPU goes away, splice its entries to the current CPU | |
3438 | * and trigger a run of the softirq | |
3439 | */ | |
3440 | if (action == CPU_DEAD) { | |
3441 | int cpu = (unsigned long) hcpu; | |
3442 | ||
3443 | local_irq_disable(); | |
3444 | list_splice_init(&per_cpu(blk_cpu_done, cpu), | |
3445 | &__get_cpu_var(blk_cpu_done)); | |
3446 | raise_softirq_irqoff(BLOCK_SOFTIRQ); | |
3447 | local_irq_enable(); | |
3448 | } | |
3449 | ||
3450 | return NOTIFY_OK; | |
3451 | } | |
3452 | ||
3453 | ||
054cc8a2 | 3454 | static struct notifier_block __devinitdata blk_cpu_notifier = { |
ff856bad JA |
3455 | .notifier_call = blk_cpu_notify, |
3456 | }; | |
3457 | ||
3458 | #endif /* CONFIG_HOTPLUG_CPU */ | |
3459 | ||
3460 | /** | |
3461 | * blk_complete_request - end I/O on a request | |
3462 | * @req: the request being processed | |
3463 | * | |
3464 | * Description: | |
3465 | * Ends all I/O on a request. It does not handle partial completions, | |
d6e05edc | 3466 | * unless the driver actually implements this in its completion callback |
ff856bad JA |
3467 | * through requeueing. Theh actual completion happens out-of-order, |
3468 | * through a softirq handler. The user must have registered a completion | |
3469 | * callback through blk_queue_softirq_done(). | |
3470 | **/ | |
3471 | ||
3472 | void blk_complete_request(struct request *req) | |
3473 | { | |
3474 | struct list_head *cpu_list; | |
3475 | unsigned long flags; | |
3476 | ||
3477 | BUG_ON(!req->q->softirq_done_fn); | |
3478 | ||
3479 | local_irq_save(flags); | |
3480 | ||
3481 | cpu_list = &__get_cpu_var(blk_cpu_done); | |
3482 | list_add_tail(&req->donelist, cpu_list); | |
3483 | raise_softirq_irqoff(BLOCK_SOFTIRQ); | |
3484 | ||
3485 | local_irq_restore(flags); | |
3486 | } | |
3487 | ||
3488 | EXPORT_SYMBOL(blk_complete_request); | |
3489 | ||
1da177e4 LT |
3490 | /* |
3491 | * queue lock must be held | |
3492 | */ | |
8ffdc655 | 3493 | void end_that_request_last(struct request *req, int uptodate) |
1da177e4 LT |
3494 | { |
3495 | struct gendisk *disk = req->rq_disk; | |
8ffdc655 TH |
3496 | int error; |
3497 | ||
3498 | /* | |
3499 | * extend uptodate bool to allow < 0 value to be direct io error | |
3500 | */ | |
3501 | error = 0; | |
3502 | if (end_io_error(uptodate)) | |
3503 | error = !uptodate ? -EIO : uptodate; | |
1da177e4 LT |
3504 | |
3505 | if (unlikely(laptop_mode) && blk_fs_request(req)) | |
3506 | laptop_io_completion(); | |
3507 | ||
fd0ff8aa JA |
3508 | /* |
3509 | * Account IO completion. bar_rq isn't accounted as a normal | |
3510 | * IO on queueing nor completion. Accounting the containing | |
3511 | * request is enough. | |
3512 | */ | |
3513 | if (disk && blk_fs_request(req) && req != &req->q->bar_rq) { | |
1da177e4 | 3514 | unsigned long duration = jiffies - req->start_time; |
a362357b JA |
3515 | const int rw = rq_data_dir(req); |
3516 | ||
3517 | __disk_stat_inc(disk, ios[rw]); | |
3518 | __disk_stat_add(disk, ticks[rw], duration); | |
1da177e4 LT |
3519 | disk_round_stats(disk); |
3520 | disk->in_flight--; | |
3521 | } | |
3522 | if (req->end_io) | |
8ffdc655 | 3523 | req->end_io(req, error); |
1da177e4 LT |
3524 | else |
3525 | __blk_put_request(req->q, req); | |
3526 | } | |
3527 | ||
3528 | EXPORT_SYMBOL(end_that_request_last); | |
3529 | ||
3530 | void end_request(struct request *req, int uptodate) | |
3531 | { | |
3532 | if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) { | |
3533 | add_disk_randomness(req->rq_disk); | |
3534 | blkdev_dequeue_request(req); | |
8ffdc655 | 3535 | end_that_request_last(req, uptodate); |
1da177e4 LT |
3536 | } |
3537 | } | |
3538 | ||
3539 | EXPORT_SYMBOL(end_request); | |
3540 | ||
3541 | void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio) | |
3542 | { | |
4aff5e23 JA |
3543 | /* first two bits are identical in rq->cmd_flags and bio->bi_rw */ |
3544 | rq->cmd_flags |= (bio->bi_rw & 3); | |
1da177e4 LT |
3545 | |
3546 | rq->nr_phys_segments = bio_phys_segments(q, bio); | |
3547 | rq->nr_hw_segments = bio_hw_segments(q, bio); | |
3548 | rq->current_nr_sectors = bio_cur_sectors(bio); | |
3549 | rq->hard_cur_sectors = rq->current_nr_sectors; | |
3550 | rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio); | |
3551 | rq->buffer = bio_data(bio); | |
3552 | ||
3553 | rq->bio = rq->biotail = bio; | |
3554 | } | |
3555 | ||
3556 | EXPORT_SYMBOL(blk_rq_bio_prep); | |
3557 | ||
3558 | int kblockd_schedule_work(struct work_struct *work) | |
3559 | { | |
3560 | return queue_work(kblockd_workqueue, work); | |
3561 | } | |
3562 | ||
3563 | EXPORT_SYMBOL(kblockd_schedule_work); | |
3564 | ||
3565 | void kblockd_flush(void) | |
3566 | { | |
3567 | flush_workqueue(kblockd_workqueue); | |
3568 | } | |
3569 | EXPORT_SYMBOL(kblockd_flush); | |
3570 | ||
3571 | int __init blk_dev_init(void) | |
3572 | { | |
ff856bad JA |
3573 | int i; |
3574 | ||
1da177e4 LT |
3575 | kblockd_workqueue = create_workqueue("kblockd"); |
3576 | if (!kblockd_workqueue) | |
3577 | panic("Failed to create kblockd\n"); | |
3578 | ||
3579 | request_cachep = kmem_cache_create("blkdev_requests", | |
3580 | sizeof(struct request), 0, SLAB_PANIC, NULL, NULL); | |
3581 | ||
3582 | requestq_cachep = kmem_cache_create("blkdev_queue", | |
3583 | sizeof(request_queue_t), 0, SLAB_PANIC, NULL, NULL); | |
3584 | ||
3585 | iocontext_cachep = kmem_cache_create("blkdev_ioc", | |
3586 | sizeof(struct io_context), 0, SLAB_PANIC, NULL, NULL); | |
3587 | ||
0a945022 | 3588 | for_each_possible_cpu(i) |
ff856bad JA |
3589 | INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i)); |
3590 | ||
3591 | open_softirq(BLOCK_SOFTIRQ, blk_done_softirq, NULL); | |
5a67e4c5 | 3592 | register_hotcpu_notifier(&blk_cpu_notifier); |
ff856bad | 3593 | |
1da177e4 LT |
3594 | blk_max_low_pfn = max_low_pfn; |
3595 | blk_max_pfn = max_pfn; | |
3596 | ||
3597 | return 0; | |
3598 | } | |
3599 | ||
3600 | /* | |
3601 | * IO Context helper functions | |
3602 | */ | |
3603 | void put_io_context(struct io_context *ioc) | |
3604 | { | |
3605 | if (ioc == NULL) | |
3606 | return; | |
3607 | ||
3608 | BUG_ON(atomic_read(&ioc->refcount) == 0); | |
3609 | ||
3610 | if (atomic_dec_and_test(&ioc->refcount)) { | |
e2d74ac0 JA |
3611 | struct cfq_io_context *cic; |
3612 | ||
334e94de | 3613 | rcu_read_lock(); |
1da177e4 LT |
3614 | if (ioc->aic && ioc->aic->dtor) |
3615 | ioc->aic->dtor(ioc->aic); | |
e2d74ac0 | 3616 | if (ioc->cic_root.rb_node != NULL) { |
7143dd4b JA |
3617 | struct rb_node *n = rb_first(&ioc->cic_root); |
3618 | ||
3619 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
e2d74ac0 JA |
3620 | cic->dtor(ioc); |
3621 | } | |
334e94de | 3622 | rcu_read_unlock(); |
1da177e4 LT |
3623 | |
3624 | kmem_cache_free(iocontext_cachep, ioc); | |
3625 | } | |
3626 | } | |
3627 | EXPORT_SYMBOL(put_io_context); | |
3628 | ||
3629 | /* Called by the exitting task */ | |
3630 | void exit_io_context(void) | |
3631 | { | |
3632 | unsigned long flags; | |
3633 | struct io_context *ioc; | |
e2d74ac0 | 3634 | struct cfq_io_context *cic; |
1da177e4 LT |
3635 | |
3636 | local_irq_save(flags); | |
22e2c507 | 3637 | task_lock(current); |
1da177e4 LT |
3638 | ioc = current->io_context; |
3639 | current->io_context = NULL; | |
22e2c507 JA |
3640 | ioc->task = NULL; |
3641 | task_unlock(current); | |
1da177e4 LT |
3642 | local_irq_restore(flags); |
3643 | ||
3644 | if (ioc->aic && ioc->aic->exit) | |
3645 | ioc->aic->exit(ioc->aic); | |
e2d74ac0 JA |
3646 | if (ioc->cic_root.rb_node != NULL) { |
3647 | cic = rb_entry(rb_first(&ioc->cic_root), struct cfq_io_context, rb_node); | |
3648 | cic->exit(ioc); | |
3649 | } | |
3650 | ||
1da177e4 LT |
3651 | put_io_context(ioc); |
3652 | } | |
3653 | ||
3654 | /* | |
3655 | * If the current task has no IO context then create one and initialise it. | |
fb3cc432 | 3656 | * Otherwise, return its existing IO context. |
1da177e4 | 3657 | * |
fb3cc432 NP |
3658 | * This returned IO context doesn't have a specifically elevated refcount, |
3659 | * but since the current task itself holds a reference, the context can be | |
3660 | * used in general code, so long as it stays within `current` context. | |
1da177e4 | 3661 | */ |
8267e268 | 3662 | struct io_context *current_io_context(gfp_t gfp_flags) |
1da177e4 LT |
3663 | { |
3664 | struct task_struct *tsk = current; | |
1da177e4 LT |
3665 | struct io_context *ret; |
3666 | ||
1da177e4 | 3667 | ret = tsk->io_context; |
fb3cc432 NP |
3668 | if (likely(ret)) |
3669 | return ret; | |
1da177e4 LT |
3670 | |
3671 | ret = kmem_cache_alloc(iocontext_cachep, gfp_flags); | |
3672 | if (ret) { | |
3673 | atomic_set(&ret->refcount, 1); | |
22e2c507 JA |
3674 | ret->task = current; |
3675 | ret->set_ioprio = NULL; | |
1da177e4 LT |
3676 | ret->last_waited = jiffies; /* doesn't matter... */ |
3677 | ret->nr_batch_requests = 0; /* because this is 0 */ | |
3678 | ret->aic = NULL; | |
e2d74ac0 | 3679 | ret->cic_root.rb_node = NULL; |
9f83e45e ON |
3680 | /* make sure set_task_ioprio() sees the settings above */ |
3681 | smp_wmb(); | |
fb3cc432 NP |
3682 | tsk->io_context = ret; |
3683 | } | |
1da177e4 | 3684 | |
fb3cc432 NP |
3685 | return ret; |
3686 | } | |
3687 | EXPORT_SYMBOL(current_io_context); | |
1da177e4 | 3688 | |
fb3cc432 NP |
3689 | /* |
3690 | * If the current task has no IO context then create one and initialise it. | |
3691 | * If it does have a context, take a ref on it. | |
3692 | * | |
3693 | * This is always called in the context of the task which submitted the I/O. | |
3694 | */ | |
8267e268 | 3695 | struct io_context *get_io_context(gfp_t gfp_flags) |
fb3cc432 NP |
3696 | { |
3697 | struct io_context *ret; | |
3698 | ret = current_io_context(gfp_flags); | |
3699 | if (likely(ret)) | |
1da177e4 | 3700 | atomic_inc(&ret->refcount); |
1da177e4 LT |
3701 | return ret; |
3702 | } | |
3703 | EXPORT_SYMBOL(get_io_context); | |
3704 | ||
3705 | void copy_io_context(struct io_context **pdst, struct io_context **psrc) | |
3706 | { | |
3707 | struct io_context *src = *psrc; | |
3708 | struct io_context *dst = *pdst; | |
3709 | ||
3710 | if (src) { | |
3711 | BUG_ON(atomic_read(&src->refcount) == 0); | |
3712 | atomic_inc(&src->refcount); | |
3713 | put_io_context(dst); | |
3714 | *pdst = src; | |
3715 | } | |
3716 | } | |
3717 | EXPORT_SYMBOL(copy_io_context); | |
3718 | ||
3719 | void swap_io_context(struct io_context **ioc1, struct io_context **ioc2) | |
3720 | { | |
3721 | struct io_context *temp; | |
3722 | temp = *ioc1; | |
3723 | *ioc1 = *ioc2; | |
3724 | *ioc2 = temp; | |
3725 | } | |
3726 | EXPORT_SYMBOL(swap_io_context); | |
3727 | ||
3728 | /* | |
3729 | * sysfs parts below | |
3730 | */ | |
3731 | struct queue_sysfs_entry { | |
3732 | struct attribute attr; | |
3733 | ssize_t (*show)(struct request_queue *, char *); | |
3734 | ssize_t (*store)(struct request_queue *, const char *, size_t); | |
3735 | }; | |
3736 | ||
3737 | static ssize_t | |
3738 | queue_var_show(unsigned int var, char *page) | |
3739 | { | |
3740 | return sprintf(page, "%d\n", var); | |
3741 | } | |
3742 | ||
3743 | static ssize_t | |
3744 | queue_var_store(unsigned long *var, const char *page, size_t count) | |
3745 | { | |
3746 | char *p = (char *) page; | |
3747 | ||
3748 | *var = simple_strtoul(p, &p, 10); | |
3749 | return count; | |
3750 | } | |
3751 | ||
3752 | static ssize_t queue_requests_show(struct request_queue *q, char *page) | |
3753 | { | |
3754 | return queue_var_show(q->nr_requests, (page)); | |
3755 | } | |
3756 | ||
3757 | static ssize_t | |
3758 | queue_requests_store(struct request_queue *q, const char *page, size_t count) | |
3759 | { | |
3760 | struct request_list *rl = &q->rq; | |
c981ff9f AV |
3761 | unsigned long nr; |
3762 | int ret = queue_var_store(&nr, page, count); | |
3763 | if (nr < BLKDEV_MIN_RQ) | |
3764 | nr = BLKDEV_MIN_RQ; | |
1da177e4 | 3765 | |
c981ff9f AV |
3766 | spin_lock_irq(q->queue_lock); |
3767 | q->nr_requests = nr; | |
1da177e4 LT |
3768 | blk_queue_congestion_threshold(q); |
3769 | ||
3770 | if (rl->count[READ] >= queue_congestion_on_threshold(q)) | |
3771 | set_queue_congested(q, READ); | |
3772 | else if (rl->count[READ] < queue_congestion_off_threshold(q)) | |
3773 | clear_queue_congested(q, READ); | |
3774 | ||
3775 | if (rl->count[WRITE] >= queue_congestion_on_threshold(q)) | |
3776 | set_queue_congested(q, WRITE); | |
3777 | else if (rl->count[WRITE] < queue_congestion_off_threshold(q)) | |
3778 | clear_queue_congested(q, WRITE); | |
3779 | ||
3780 | if (rl->count[READ] >= q->nr_requests) { | |
3781 | blk_set_queue_full(q, READ); | |
3782 | } else if (rl->count[READ]+1 <= q->nr_requests) { | |
3783 | blk_clear_queue_full(q, READ); | |
3784 | wake_up(&rl->wait[READ]); | |
3785 | } | |
3786 | ||
3787 | if (rl->count[WRITE] >= q->nr_requests) { | |
3788 | blk_set_queue_full(q, WRITE); | |
3789 | } else if (rl->count[WRITE]+1 <= q->nr_requests) { | |
3790 | blk_clear_queue_full(q, WRITE); | |
3791 | wake_up(&rl->wait[WRITE]); | |
3792 | } | |
c981ff9f | 3793 | spin_unlock_irq(q->queue_lock); |
1da177e4 LT |
3794 | return ret; |
3795 | } | |
3796 | ||
3797 | static ssize_t queue_ra_show(struct request_queue *q, char *page) | |
3798 | { | |
3799 | int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10); | |
3800 | ||
3801 | return queue_var_show(ra_kb, (page)); | |
3802 | } | |
3803 | ||
3804 | static ssize_t | |
3805 | queue_ra_store(struct request_queue *q, const char *page, size_t count) | |
3806 | { | |
3807 | unsigned long ra_kb; | |
3808 | ssize_t ret = queue_var_store(&ra_kb, page, count); | |
3809 | ||
3810 | spin_lock_irq(q->queue_lock); | |
3811 | if (ra_kb > (q->max_sectors >> 1)) | |
3812 | ra_kb = (q->max_sectors >> 1); | |
3813 | ||
3814 | q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10); | |
3815 | spin_unlock_irq(q->queue_lock); | |
3816 | ||
3817 | return ret; | |
3818 | } | |
3819 | ||
3820 | static ssize_t queue_max_sectors_show(struct request_queue *q, char *page) | |
3821 | { | |
3822 | int max_sectors_kb = q->max_sectors >> 1; | |
3823 | ||
3824 | return queue_var_show(max_sectors_kb, (page)); | |
3825 | } | |
3826 | ||
3827 | static ssize_t | |
3828 | queue_max_sectors_store(struct request_queue *q, const char *page, size_t count) | |
3829 | { | |
3830 | unsigned long max_sectors_kb, | |
3831 | max_hw_sectors_kb = q->max_hw_sectors >> 1, | |
3832 | page_kb = 1 << (PAGE_CACHE_SHIFT - 10); | |
3833 | ssize_t ret = queue_var_store(&max_sectors_kb, page, count); | |
3834 | int ra_kb; | |
3835 | ||
3836 | if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb) | |
3837 | return -EINVAL; | |
3838 | /* | |
3839 | * Take the queue lock to update the readahead and max_sectors | |
3840 | * values synchronously: | |
3841 | */ | |
3842 | spin_lock_irq(q->queue_lock); | |
3843 | /* | |
3844 | * Trim readahead window as well, if necessary: | |
3845 | */ | |
3846 | ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10); | |
3847 | if (ra_kb > max_sectors_kb) | |
3848 | q->backing_dev_info.ra_pages = | |
3849 | max_sectors_kb >> (PAGE_CACHE_SHIFT - 10); | |
3850 | ||
3851 | q->max_sectors = max_sectors_kb << 1; | |
3852 | spin_unlock_irq(q->queue_lock); | |
3853 | ||
3854 | return ret; | |
3855 | } | |
3856 | ||
3857 | static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page) | |
3858 | { | |
3859 | int max_hw_sectors_kb = q->max_hw_sectors >> 1; | |
3860 | ||
3861 | return queue_var_show(max_hw_sectors_kb, (page)); | |
3862 | } | |
3863 | ||
3864 | ||
3865 | static struct queue_sysfs_entry queue_requests_entry = { | |
3866 | .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR }, | |
3867 | .show = queue_requests_show, | |
3868 | .store = queue_requests_store, | |
3869 | }; | |
3870 | ||
3871 | static struct queue_sysfs_entry queue_ra_entry = { | |
3872 | .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR }, | |
3873 | .show = queue_ra_show, | |
3874 | .store = queue_ra_store, | |
3875 | }; | |
3876 | ||
3877 | static struct queue_sysfs_entry queue_max_sectors_entry = { | |
3878 | .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR }, | |
3879 | .show = queue_max_sectors_show, | |
3880 | .store = queue_max_sectors_store, | |
3881 | }; | |
3882 | ||
3883 | static struct queue_sysfs_entry queue_max_hw_sectors_entry = { | |
3884 | .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO }, | |
3885 | .show = queue_max_hw_sectors_show, | |
3886 | }; | |
3887 | ||
3888 | static struct queue_sysfs_entry queue_iosched_entry = { | |
3889 | .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR }, | |
3890 | .show = elv_iosched_show, | |
3891 | .store = elv_iosched_store, | |
3892 | }; | |
3893 | ||
3894 | static struct attribute *default_attrs[] = { | |
3895 | &queue_requests_entry.attr, | |
3896 | &queue_ra_entry.attr, | |
3897 | &queue_max_hw_sectors_entry.attr, | |
3898 | &queue_max_sectors_entry.attr, | |
3899 | &queue_iosched_entry.attr, | |
3900 | NULL, | |
3901 | }; | |
3902 | ||
3903 | #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr) | |
3904 | ||
3905 | static ssize_t | |
3906 | queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
3907 | { | |
3908 | struct queue_sysfs_entry *entry = to_queue(attr); | |
483f4afc AV |
3909 | request_queue_t *q = container_of(kobj, struct request_queue, kobj); |
3910 | ssize_t res; | |
1da177e4 | 3911 | |
1da177e4 | 3912 | if (!entry->show) |
6c1852a0 | 3913 | return -EIO; |
483f4afc AV |
3914 | mutex_lock(&q->sysfs_lock); |
3915 | if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) { | |
3916 | mutex_unlock(&q->sysfs_lock); | |
3917 | return -ENOENT; | |
3918 | } | |
3919 | res = entry->show(q, page); | |
3920 | mutex_unlock(&q->sysfs_lock); | |
3921 | return res; | |
1da177e4 LT |
3922 | } |
3923 | ||
3924 | static ssize_t | |
3925 | queue_attr_store(struct kobject *kobj, struct attribute *attr, | |
3926 | const char *page, size_t length) | |
3927 | { | |
3928 | struct queue_sysfs_entry *entry = to_queue(attr); | |
483f4afc AV |
3929 | request_queue_t *q = container_of(kobj, struct request_queue, kobj); |
3930 | ||
3931 | ssize_t res; | |
1da177e4 | 3932 | |
1da177e4 | 3933 | if (!entry->store) |
6c1852a0 | 3934 | return -EIO; |
483f4afc AV |
3935 | mutex_lock(&q->sysfs_lock); |
3936 | if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) { | |
3937 | mutex_unlock(&q->sysfs_lock); | |
3938 | return -ENOENT; | |
3939 | } | |
3940 | res = entry->store(q, page, length); | |
3941 | mutex_unlock(&q->sysfs_lock); | |
3942 | return res; | |
1da177e4 LT |
3943 | } |
3944 | ||
3945 | static struct sysfs_ops queue_sysfs_ops = { | |
3946 | .show = queue_attr_show, | |
3947 | .store = queue_attr_store, | |
3948 | }; | |
3949 | ||
93d17d3d | 3950 | static struct kobj_type queue_ktype = { |
1da177e4 LT |
3951 | .sysfs_ops = &queue_sysfs_ops, |
3952 | .default_attrs = default_attrs, | |
483f4afc | 3953 | .release = blk_release_queue, |
1da177e4 LT |
3954 | }; |
3955 | ||
3956 | int blk_register_queue(struct gendisk *disk) | |
3957 | { | |
3958 | int ret; | |
3959 | ||
3960 | request_queue_t *q = disk->queue; | |
3961 | ||
3962 | if (!q || !q->request_fn) | |
3963 | return -ENXIO; | |
3964 | ||
3965 | q->kobj.parent = kobject_get(&disk->kobj); | |
1da177e4 | 3966 | |
483f4afc | 3967 | ret = kobject_add(&q->kobj); |
1da177e4 LT |
3968 | if (ret < 0) |
3969 | return ret; | |
3970 | ||
483f4afc AV |
3971 | kobject_uevent(&q->kobj, KOBJ_ADD); |
3972 | ||
1da177e4 LT |
3973 | ret = elv_register_queue(q); |
3974 | if (ret) { | |
483f4afc AV |
3975 | kobject_uevent(&q->kobj, KOBJ_REMOVE); |
3976 | kobject_del(&q->kobj); | |
1da177e4 LT |
3977 | return ret; |
3978 | } | |
3979 | ||
3980 | return 0; | |
3981 | } | |
3982 | ||
3983 | void blk_unregister_queue(struct gendisk *disk) | |
3984 | { | |
3985 | request_queue_t *q = disk->queue; | |
3986 | ||
3987 | if (q && q->request_fn) { | |
3988 | elv_unregister_queue(q); | |
3989 | ||
483f4afc AV |
3990 | kobject_uevent(&q->kobj, KOBJ_REMOVE); |
3991 | kobject_del(&q->kobj); | |
1da177e4 LT |
3992 | kobject_put(&disk->kobj); |
3993 | } | |
3994 | } |