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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); |
1da177e4 LT |
284 | |
285 | rq->errors = 0; | |
1da177e4 | 286 | rq->bio = rq->biotail = NULL; |
2e662b65 JA |
287 | INIT_HLIST_NODE(&rq->hash); |
288 | RB_CLEAR_NODE(&rq->rb_node); | |
22e2c507 | 289 | rq->ioprio = 0; |
1da177e4 LT |
290 | rq->buffer = NULL; |
291 | rq->ref_count = 1; | |
292 | rq->q = q; | |
1da177e4 LT |
293 | rq->special = NULL; |
294 | rq->data_len = 0; | |
295 | rq->data = NULL; | |
df46b9a4 | 296 | rq->nr_phys_segments = 0; |
1da177e4 LT |
297 | rq->sense = NULL; |
298 | rq->end_io = NULL; | |
299 | rq->end_io_data = NULL; | |
ff856bad | 300 | rq->completion_data = NULL; |
1da177e4 LT |
301 | } |
302 | ||
303 | /** | |
304 | * blk_queue_ordered - does this queue support ordered writes | |
797e7dbb TH |
305 | * @q: the request queue |
306 | * @ordered: one of QUEUE_ORDERED_* | |
fddfdeaf | 307 | * @prepare_flush_fn: rq setup helper for cache flush ordered writes |
1da177e4 LT |
308 | * |
309 | * Description: | |
310 | * For journalled file systems, doing ordered writes on a commit | |
311 | * block instead of explicitly doing wait_on_buffer (which is bad | |
312 | * for performance) can be a big win. Block drivers supporting this | |
313 | * feature should call this function and indicate so. | |
314 | * | |
315 | **/ | |
797e7dbb TH |
316 | int blk_queue_ordered(request_queue_t *q, unsigned ordered, |
317 | prepare_flush_fn *prepare_flush_fn) | |
318 | { | |
319 | if (ordered & (QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH) && | |
320 | prepare_flush_fn == NULL) { | |
321 | printk(KERN_ERR "blk_queue_ordered: prepare_flush_fn required\n"); | |
322 | return -EINVAL; | |
323 | } | |
324 | ||
325 | if (ordered != QUEUE_ORDERED_NONE && | |
326 | ordered != QUEUE_ORDERED_DRAIN && | |
327 | ordered != QUEUE_ORDERED_DRAIN_FLUSH && | |
328 | ordered != QUEUE_ORDERED_DRAIN_FUA && | |
329 | ordered != QUEUE_ORDERED_TAG && | |
330 | ordered != QUEUE_ORDERED_TAG_FLUSH && | |
331 | ordered != QUEUE_ORDERED_TAG_FUA) { | |
332 | printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered); | |
333 | return -EINVAL; | |
1da177e4 | 334 | } |
797e7dbb | 335 | |
60481b12 | 336 | q->ordered = ordered; |
797e7dbb TH |
337 | q->next_ordered = ordered; |
338 | q->prepare_flush_fn = prepare_flush_fn; | |
339 | ||
340 | return 0; | |
1da177e4 LT |
341 | } |
342 | ||
343 | EXPORT_SYMBOL(blk_queue_ordered); | |
344 | ||
345 | /** | |
346 | * blk_queue_issue_flush_fn - set function for issuing a flush | |
347 | * @q: the request queue | |
348 | * @iff: the function to be called issuing the flush | |
349 | * | |
350 | * Description: | |
351 | * If a driver supports issuing a flush command, the support is notified | |
352 | * to the block layer by defining it through this call. | |
353 | * | |
354 | **/ | |
355 | void blk_queue_issue_flush_fn(request_queue_t *q, issue_flush_fn *iff) | |
356 | { | |
357 | q->issue_flush_fn = iff; | |
358 | } | |
359 | ||
360 | EXPORT_SYMBOL(blk_queue_issue_flush_fn); | |
361 | ||
362 | /* | |
363 | * Cache flushing for ordered writes handling | |
364 | */ | |
797e7dbb | 365 | inline unsigned blk_ordered_cur_seq(request_queue_t *q) |
1da177e4 | 366 | { |
797e7dbb TH |
367 | if (!q->ordseq) |
368 | return 0; | |
369 | return 1 << ffz(q->ordseq); | |
1da177e4 LT |
370 | } |
371 | ||
797e7dbb | 372 | unsigned blk_ordered_req_seq(struct request *rq) |
1da177e4 | 373 | { |
1da177e4 LT |
374 | request_queue_t *q = rq->q; |
375 | ||
797e7dbb | 376 | BUG_ON(q->ordseq == 0); |
8922e16c | 377 | |
797e7dbb TH |
378 | if (rq == &q->pre_flush_rq) |
379 | return QUEUE_ORDSEQ_PREFLUSH; | |
380 | if (rq == &q->bar_rq) | |
381 | return QUEUE_ORDSEQ_BAR; | |
382 | if (rq == &q->post_flush_rq) | |
383 | return QUEUE_ORDSEQ_POSTFLUSH; | |
1da177e4 | 384 | |
4aff5e23 JA |
385 | if ((rq->cmd_flags & REQ_ORDERED_COLOR) == |
386 | (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR)) | |
797e7dbb TH |
387 | return QUEUE_ORDSEQ_DRAIN; |
388 | else | |
389 | return QUEUE_ORDSEQ_DONE; | |
1da177e4 LT |
390 | } |
391 | ||
797e7dbb | 392 | void blk_ordered_complete_seq(request_queue_t *q, unsigned seq, int error) |
1da177e4 | 393 | { |
797e7dbb TH |
394 | struct request *rq; |
395 | int uptodate; | |
1da177e4 | 396 | |
797e7dbb TH |
397 | if (error && !q->orderr) |
398 | q->orderr = error; | |
1da177e4 | 399 | |
797e7dbb TH |
400 | BUG_ON(q->ordseq & seq); |
401 | q->ordseq |= seq; | |
1da177e4 | 402 | |
797e7dbb TH |
403 | if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE) |
404 | return; | |
1da177e4 LT |
405 | |
406 | /* | |
797e7dbb | 407 | * Okay, sequence complete. |
1da177e4 | 408 | */ |
797e7dbb TH |
409 | rq = q->orig_bar_rq; |
410 | uptodate = q->orderr ? q->orderr : 1; | |
1da177e4 | 411 | |
797e7dbb | 412 | q->ordseq = 0; |
1da177e4 | 413 | |
797e7dbb TH |
414 | end_that_request_first(rq, uptodate, rq->hard_nr_sectors); |
415 | end_that_request_last(rq, uptodate); | |
1da177e4 LT |
416 | } |
417 | ||
797e7dbb | 418 | static void pre_flush_end_io(struct request *rq, int error) |
1da177e4 | 419 | { |
797e7dbb TH |
420 | elv_completed_request(rq->q, rq); |
421 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error); | |
422 | } | |
1da177e4 | 423 | |
797e7dbb TH |
424 | static void bar_end_io(struct request *rq, int error) |
425 | { | |
426 | elv_completed_request(rq->q, rq); | |
427 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error); | |
428 | } | |
1da177e4 | 429 | |
797e7dbb TH |
430 | static void post_flush_end_io(struct request *rq, int error) |
431 | { | |
432 | elv_completed_request(rq->q, rq); | |
433 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error); | |
434 | } | |
1da177e4 | 435 | |
797e7dbb TH |
436 | static void queue_flush(request_queue_t *q, unsigned which) |
437 | { | |
438 | struct request *rq; | |
439 | rq_end_io_fn *end_io; | |
1da177e4 | 440 | |
797e7dbb TH |
441 | if (which == QUEUE_ORDERED_PREFLUSH) { |
442 | rq = &q->pre_flush_rq; | |
443 | end_io = pre_flush_end_io; | |
444 | } else { | |
445 | rq = &q->post_flush_rq; | |
446 | end_io = post_flush_end_io; | |
1da177e4 | 447 | } |
797e7dbb | 448 | |
4aff5e23 | 449 | rq->cmd_flags = REQ_HARDBARRIER; |
797e7dbb | 450 | rq_init(q, rq); |
797e7dbb | 451 | rq->elevator_private = NULL; |
c00895ab | 452 | rq->elevator_private2 = NULL; |
797e7dbb | 453 | rq->rq_disk = q->bar_rq.rq_disk; |
797e7dbb TH |
454 | rq->end_io = end_io; |
455 | q->prepare_flush_fn(q, rq); | |
456 | ||
30e9656c | 457 | elv_insert(q, rq, ELEVATOR_INSERT_FRONT); |
1da177e4 LT |
458 | } |
459 | ||
797e7dbb TH |
460 | static inline struct request *start_ordered(request_queue_t *q, |
461 | struct request *rq) | |
1da177e4 | 462 | { |
797e7dbb TH |
463 | q->bi_size = 0; |
464 | q->orderr = 0; | |
465 | q->ordered = q->next_ordered; | |
466 | q->ordseq |= QUEUE_ORDSEQ_STARTED; | |
467 | ||
468 | /* | |
469 | * Prep proxy barrier request. | |
470 | */ | |
471 | blkdev_dequeue_request(rq); | |
472 | q->orig_bar_rq = rq; | |
473 | rq = &q->bar_rq; | |
4aff5e23 | 474 | rq->cmd_flags = 0; |
797e7dbb | 475 | rq_init(q, rq); |
4aff5e23 JA |
476 | if (bio_data_dir(q->orig_bar_rq->bio) == WRITE) |
477 | rq->cmd_flags |= REQ_RW; | |
478 | rq->cmd_flags |= q->ordered & QUEUE_ORDERED_FUA ? REQ_FUA : 0; | |
797e7dbb | 479 | rq->elevator_private = NULL; |
c00895ab | 480 | rq->elevator_private2 = NULL; |
797e7dbb TH |
481 | init_request_from_bio(rq, q->orig_bar_rq->bio); |
482 | rq->end_io = bar_end_io; | |
483 | ||
484 | /* | |
485 | * Queue ordered sequence. As we stack them at the head, we | |
486 | * need to queue in reverse order. Note that we rely on that | |
487 | * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs | |
488 | * request gets inbetween ordered sequence. | |
489 | */ | |
490 | if (q->ordered & QUEUE_ORDERED_POSTFLUSH) | |
491 | queue_flush(q, QUEUE_ORDERED_POSTFLUSH); | |
492 | else | |
493 | q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH; | |
494 | ||
30e9656c | 495 | elv_insert(q, rq, ELEVATOR_INSERT_FRONT); |
797e7dbb TH |
496 | |
497 | if (q->ordered & QUEUE_ORDERED_PREFLUSH) { | |
498 | queue_flush(q, QUEUE_ORDERED_PREFLUSH); | |
499 | rq = &q->pre_flush_rq; | |
500 | } else | |
501 | q->ordseq |= QUEUE_ORDSEQ_PREFLUSH; | |
1da177e4 | 502 | |
797e7dbb TH |
503 | if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0) |
504 | q->ordseq |= QUEUE_ORDSEQ_DRAIN; | |
505 | else | |
506 | rq = NULL; | |
507 | ||
508 | return rq; | |
1da177e4 LT |
509 | } |
510 | ||
797e7dbb | 511 | int blk_do_ordered(request_queue_t *q, struct request **rqp) |
1da177e4 | 512 | { |
9a7a67af | 513 | struct request *rq = *rqp; |
797e7dbb | 514 | int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq); |
1da177e4 | 515 | |
797e7dbb TH |
516 | if (!q->ordseq) { |
517 | if (!is_barrier) | |
518 | return 1; | |
1da177e4 | 519 | |
797e7dbb TH |
520 | if (q->next_ordered != QUEUE_ORDERED_NONE) { |
521 | *rqp = start_ordered(q, rq); | |
522 | return 1; | |
523 | } else { | |
524 | /* | |
525 | * This can happen when the queue switches to | |
526 | * ORDERED_NONE while this request is on it. | |
527 | */ | |
528 | blkdev_dequeue_request(rq); | |
529 | end_that_request_first(rq, -EOPNOTSUPP, | |
530 | rq->hard_nr_sectors); | |
531 | end_that_request_last(rq, -EOPNOTSUPP); | |
532 | *rqp = NULL; | |
533 | return 0; | |
534 | } | |
535 | } | |
1da177e4 | 536 | |
9a7a67af JA |
537 | /* |
538 | * Ordered sequence in progress | |
539 | */ | |
540 | ||
541 | /* Special requests are not subject to ordering rules. */ | |
542 | if (!blk_fs_request(rq) && | |
543 | rq != &q->pre_flush_rq && rq != &q->post_flush_rq) | |
544 | return 1; | |
545 | ||
797e7dbb | 546 | if (q->ordered & QUEUE_ORDERED_TAG) { |
9a7a67af | 547 | /* Ordered by tag. Blocking the next barrier is enough. */ |
797e7dbb TH |
548 | if (is_barrier && rq != &q->bar_rq) |
549 | *rqp = NULL; | |
9a7a67af JA |
550 | } else { |
551 | /* Ordered by draining. Wait for turn. */ | |
552 | WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q)); | |
553 | if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q)) | |
554 | *rqp = NULL; | |
1da177e4 LT |
555 | } |
556 | ||
557 | return 1; | |
558 | } | |
559 | ||
797e7dbb | 560 | static int flush_dry_bio_endio(struct bio *bio, unsigned int bytes, int error) |
1da177e4 | 561 | { |
797e7dbb TH |
562 | request_queue_t *q = bio->bi_private; |
563 | struct bio_vec *bvec; | |
564 | int i; | |
565 | ||
566 | /* | |
567 | * This is dry run, restore bio_sector and size. We'll finish | |
568 | * this request again with the original bi_end_io after an | |
569 | * error occurs or post flush is complete. | |
570 | */ | |
571 | q->bi_size += bytes; | |
572 | ||
573 | if (bio->bi_size) | |
574 | return 1; | |
575 | ||
576 | /* Rewind bvec's */ | |
577 | bio->bi_idx = 0; | |
578 | bio_for_each_segment(bvec, bio, i) { | |
579 | bvec->bv_len += bvec->bv_offset; | |
580 | bvec->bv_offset = 0; | |
581 | } | |
582 | ||
583 | /* Reset bio */ | |
584 | set_bit(BIO_UPTODATE, &bio->bi_flags); | |
585 | bio->bi_size = q->bi_size; | |
586 | bio->bi_sector -= (q->bi_size >> 9); | |
587 | q->bi_size = 0; | |
588 | ||
589 | return 0; | |
1da177e4 | 590 | } |
1da177e4 | 591 | |
797e7dbb TH |
592 | static inline int ordered_bio_endio(struct request *rq, struct bio *bio, |
593 | unsigned int nbytes, int error) | |
1da177e4 | 594 | { |
797e7dbb TH |
595 | request_queue_t *q = rq->q; |
596 | bio_end_io_t *endio; | |
597 | void *private; | |
598 | ||
599 | if (&q->bar_rq != rq) | |
600 | return 0; | |
601 | ||
602 | /* | |
603 | * Okay, this is the barrier request in progress, dry finish it. | |
604 | */ | |
605 | if (error && !q->orderr) | |
606 | q->orderr = error; | |
607 | ||
608 | endio = bio->bi_end_io; | |
609 | private = bio->bi_private; | |
610 | bio->bi_end_io = flush_dry_bio_endio; | |
611 | bio->bi_private = q; | |
612 | ||
613 | bio_endio(bio, nbytes, error); | |
614 | ||
615 | bio->bi_end_io = endio; | |
616 | bio->bi_private = private; | |
617 | ||
618 | return 1; | |
1da177e4 | 619 | } |
1da177e4 LT |
620 | |
621 | /** | |
622 | * blk_queue_bounce_limit - set bounce buffer limit for queue | |
623 | * @q: the request queue for the device | |
624 | * @dma_addr: bus address limit | |
625 | * | |
626 | * Description: | |
627 | * Different hardware can have different requirements as to what pages | |
628 | * it can do I/O directly to. A low level driver can call | |
629 | * blk_queue_bounce_limit to have lower memory pages allocated as bounce | |
5ee1af9f | 630 | * buffers for doing I/O to pages residing above @page. |
1da177e4 LT |
631 | **/ |
632 | void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr) | |
633 | { | |
634 | unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT; | |
5ee1af9f AK |
635 | int dma = 0; |
636 | ||
637 | q->bounce_gfp = GFP_NOIO; | |
638 | #if BITS_PER_LONG == 64 | |
639 | /* Assume anything <= 4GB can be handled by IOMMU. | |
640 | Actually some IOMMUs can handle everything, but I don't | |
641 | know of a way to test this here. */ | |
8269730b | 642 | if (bounce_pfn < (min_t(u64,0xffffffff,BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) |
5ee1af9f AK |
643 | dma = 1; |
644 | q->bounce_pfn = max_low_pfn; | |
645 | #else | |
646 | if (bounce_pfn < blk_max_low_pfn) | |
647 | dma = 1; | |
648 | q->bounce_pfn = bounce_pfn; | |
649 | #endif | |
650 | if (dma) { | |
1da177e4 LT |
651 | init_emergency_isa_pool(); |
652 | q->bounce_gfp = GFP_NOIO | GFP_DMA; | |
5ee1af9f AK |
653 | q->bounce_pfn = bounce_pfn; |
654 | } | |
1da177e4 LT |
655 | } |
656 | ||
657 | EXPORT_SYMBOL(blk_queue_bounce_limit); | |
658 | ||
659 | /** | |
660 | * blk_queue_max_sectors - set max sectors for a request for this queue | |
661 | * @q: the request queue for the device | |
662 | * @max_sectors: max sectors in the usual 512b unit | |
663 | * | |
664 | * Description: | |
665 | * Enables a low level driver to set an upper limit on the size of | |
666 | * received requests. | |
667 | **/ | |
2cb2e147 | 668 | void blk_queue_max_sectors(request_queue_t *q, unsigned int max_sectors) |
1da177e4 LT |
669 | { |
670 | if ((max_sectors << 9) < PAGE_CACHE_SIZE) { | |
671 | max_sectors = 1 << (PAGE_CACHE_SHIFT - 9); | |
672 | printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors); | |
673 | } | |
674 | ||
defd94b7 MC |
675 | if (BLK_DEF_MAX_SECTORS > max_sectors) |
676 | q->max_hw_sectors = q->max_sectors = max_sectors; | |
677 | else { | |
678 | q->max_sectors = BLK_DEF_MAX_SECTORS; | |
679 | q->max_hw_sectors = max_sectors; | |
680 | } | |
1da177e4 LT |
681 | } |
682 | ||
683 | EXPORT_SYMBOL(blk_queue_max_sectors); | |
684 | ||
685 | /** | |
686 | * blk_queue_max_phys_segments - set max phys segments for a request for this queue | |
687 | * @q: the request queue for the device | |
688 | * @max_segments: max number of segments | |
689 | * | |
690 | * Description: | |
691 | * Enables a low level driver to set an upper limit on the number of | |
692 | * physical data segments in a request. This would be the largest sized | |
693 | * scatter list the driver could handle. | |
694 | **/ | |
695 | void blk_queue_max_phys_segments(request_queue_t *q, unsigned short max_segments) | |
696 | { | |
697 | if (!max_segments) { | |
698 | max_segments = 1; | |
699 | printk("%s: set to minimum %d\n", __FUNCTION__, max_segments); | |
700 | } | |
701 | ||
702 | q->max_phys_segments = max_segments; | |
703 | } | |
704 | ||
705 | EXPORT_SYMBOL(blk_queue_max_phys_segments); | |
706 | ||
707 | /** | |
708 | * blk_queue_max_hw_segments - set max hw segments for a request for this queue | |
709 | * @q: the request queue for the device | |
710 | * @max_segments: max number of segments | |
711 | * | |
712 | * Description: | |
713 | * Enables a low level driver to set an upper limit on the number of | |
714 | * hw data segments in a request. This would be the largest number of | |
715 | * address/length pairs the host adapter can actually give as once | |
716 | * to the device. | |
717 | **/ | |
718 | void blk_queue_max_hw_segments(request_queue_t *q, unsigned short max_segments) | |
719 | { | |
720 | if (!max_segments) { | |
721 | max_segments = 1; | |
722 | printk("%s: set to minimum %d\n", __FUNCTION__, max_segments); | |
723 | } | |
724 | ||
725 | q->max_hw_segments = max_segments; | |
726 | } | |
727 | ||
728 | EXPORT_SYMBOL(blk_queue_max_hw_segments); | |
729 | ||
730 | /** | |
731 | * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg | |
732 | * @q: the request queue for the device | |
733 | * @max_size: max size of segment in bytes | |
734 | * | |
735 | * Description: | |
736 | * Enables a low level driver to set an upper limit on the size of a | |
737 | * coalesced segment | |
738 | **/ | |
739 | void blk_queue_max_segment_size(request_queue_t *q, unsigned int max_size) | |
740 | { | |
741 | if (max_size < PAGE_CACHE_SIZE) { | |
742 | max_size = PAGE_CACHE_SIZE; | |
743 | printk("%s: set to minimum %d\n", __FUNCTION__, max_size); | |
744 | } | |
745 | ||
746 | q->max_segment_size = max_size; | |
747 | } | |
748 | ||
749 | EXPORT_SYMBOL(blk_queue_max_segment_size); | |
750 | ||
751 | /** | |
752 | * blk_queue_hardsect_size - set hardware sector size for the queue | |
753 | * @q: the request queue for the device | |
754 | * @size: the hardware sector size, in bytes | |
755 | * | |
756 | * Description: | |
757 | * This should typically be set to the lowest possible sector size | |
758 | * that the hardware can operate on (possible without reverting to | |
759 | * even internal read-modify-write operations). Usually the default | |
760 | * of 512 covers most hardware. | |
761 | **/ | |
762 | void blk_queue_hardsect_size(request_queue_t *q, unsigned short size) | |
763 | { | |
764 | q->hardsect_size = size; | |
765 | } | |
766 | ||
767 | EXPORT_SYMBOL(blk_queue_hardsect_size); | |
768 | ||
769 | /* | |
770 | * Returns the minimum that is _not_ zero, unless both are zero. | |
771 | */ | |
772 | #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) | |
773 | ||
774 | /** | |
775 | * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers | |
776 | * @t: the stacking driver (top) | |
777 | * @b: the underlying device (bottom) | |
778 | **/ | |
779 | void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b) | |
780 | { | |
781 | /* zero is "infinity" */ | |
defd94b7 MC |
782 | t->max_sectors = min_not_zero(t->max_sectors,b->max_sectors); |
783 | t->max_hw_sectors = min_not_zero(t->max_hw_sectors,b->max_hw_sectors); | |
1da177e4 LT |
784 | |
785 | t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments); | |
786 | t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments); | |
787 | t->max_segment_size = min(t->max_segment_size,b->max_segment_size); | |
788 | t->hardsect_size = max(t->hardsect_size,b->hardsect_size); | |
89e5c8b5 N |
789 | if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) |
790 | clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags); | |
1da177e4 LT |
791 | } |
792 | ||
793 | EXPORT_SYMBOL(blk_queue_stack_limits); | |
794 | ||
795 | /** | |
796 | * blk_queue_segment_boundary - set boundary rules for segment merging | |
797 | * @q: the request queue for the device | |
798 | * @mask: the memory boundary mask | |
799 | **/ | |
800 | void blk_queue_segment_boundary(request_queue_t *q, unsigned long mask) | |
801 | { | |
802 | if (mask < PAGE_CACHE_SIZE - 1) { | |
803 | mask = PAGE_CACHE_SIZE - 1; | |
804 | printk("%s: set to minimum %lx\n", __FUNCTION__, mask); | |
805 | } | |
806 | ||
807 | q->seg_boundary_mask = mask; | |
808 | } | |
809 | ||
810 | EXPORT_SYMBOL(blk_queue_segment_boundary); | |
811 | ||
812 | /** | |
813 | * blk_queue_dma_alignment - set dma length and memory alignment | |
814 | * @q: the request queue for the device | |
815 | * @mask: alignment mask | |
816 | * | |
817 | * description: | |
818 | * set required memory and length aligment for direct dma transactions. | |
819 | * this is used when buiding direct io requests for the queue. | |
820 | * | |
821 | **/ | |
822 | void blk_queue_dma_alignment(request_queue_t *q, int mask) | |
823 | { | |
824 | q->dma_alignment = mask; | |
825 | } | |
826 | ||
827 | EXPORT_SYMBOL(blk_queue_dma_alignment); | |
828 | ||
829 | /** | |
830 | * blk_queue_find_tag - find a request by its tag and queue | |
1da177e4 LT |
831 | * @q: The request queue for the device |
832 | * @tag: The tag of the request | |
833 | * | |
834 | * Notes: | |
835 | * Should be used when a device returns a tag and you want to match | |
836 | * it with a request. | |
837 | * | |
838 | * no locks need be held. | |
839 | **/ | |
840 | struct request *blk_queue_find_tag(request_queue_t *q, int tag) | |
841 | { | |
842 | struct blk_queue_tag *bqt = q->queue_tags; | |
843 | ||
ba025082 | 844 | if (unlikely(bqt == NULL || tag >= bqt->real_max_depth)) |
1da177e4 LT |
845 | return NULL; |
846 | ||
847 | return bqt->tag_index[tag]; | |
848 | } | |
849 | ||
850 | EXPORT_SYMBOL(blk_queue_find_tag); | |
851 | ||
852 | /** | |
492dfb48 JB |
853 | * __blk_free_tags - release a given set of tag maintenance info |
854 | * @bqt: the tag map to free | |
1da177e4 | 855 | * |
492dfb48 JB |
856 | * Tries to free the specified @bqt@. Returns true if it was |
857 | * actually freed and false if there are still references using it | |
858 | */ | |
859 | static int __blk_free_tags(struct blk_queue_tag *bqt) | |
1da177e4 | 860 | { |
492dfb48 | 861 | int retval; |
1da177e4 | 862 | |
492dfb48 JB |
863 | retval = atomic_dec_and_test(&bqt->refcnt); |
864 | if (retval) { | |
1da177e4 LT |
865 | BUG_ON(bqt->busy); |
866 | BUG_ON(!list_empty(&bqt->busy_list)); | |
867 | ||
868 | kfree(bqt->tag_index); | |
869 | bqt->tag_index = NULL; | |
870 | ||
871 | kfree(bqt->tag_map); | |
872 | bqt->tag_map = NULL; | |
873 | ||
874 | kfree(bqt); | |
492dfb48 | 875 | |
1da177e4 LT |
876 | } |
877 | ||
492dfb48 JB |
878 | return retval; |
879 | } | |
880 | ||
881 | /** | |
882 | * __blk_queue_free_tags - release tag maintenance info | |
883 | * @q: the request queue for the device | |
884 | * | |
885 | * Notes: | |
886 | * blk_cleanup_queue() will take care of calling this function, if tagging | |
887 | * has been used. So there's no need to call this directly. | |
888 | **/ | |
889 | static void __blk_queue_free_tags(request_queue_t *q) | |
890 | { | |
891 | struct blk_queue_tag *bqt = q->queue_tags; | |
892 | ||
893 | if (!bqt) | |
894 | return; | |
895 | ||
896 | __blk_free_tags(bqt); | |
897 | ||
1da177e4 LT |
898 | q->queue_tags = NULL; |
899 | q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED); | |
900 | } | |
901 | ||
492dfb48 JB |
902 | |
903 | /** | |
904 | * blk_free_tags - release a given set of tag maintenance info | |
905 | * @bqt: the tag map to free | |
906 | * | |
907 | * For externally managed @bqt@ frees the map. Callers of this | |
908 | * function must guarantee to have released all the queues that | |
909 | * might have been using this tag map. | |
910 | */ | |
911 | void blk_free_tags(struct blk_queue_tag *bqt) | |
912 | { | |
913 | if (unlikely(!__blk_free_tags(bqt))) | |
914 | BUG(); | |
915 | } | |
916 | EXPORT_SYMBOL(blk_free_tags); | |
917 | ||
1da177e4 LT |
918 | /** |
919 | * blk_queue_free_tags - release tag maintenance info | |
920 | * @q: the request queue for the device | |
921 | * | |
922 | * Notes: | |
923 | * This is used to disabled tagged queuing to a device, yet leave | |
924 | * queue in function. | |
925 | **/ | |
926 | void blk_queue_free_tags(request_queue_t *q) | |
927 | { | |
928 | clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); | |
929 | } | |
930 | ||
931 | EXPORT_SYMBOL(blk_queue_free_tags); | |
932 | ||
933 | static int | |
934 | init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth) | |
935 | { | |
1da177e4 LT |
936 | struct request **tag_index; |
937 | unsigned long *tag_map; | |
fa72b903 | 938 | int nr_ulongs; |
1da177e4 | 939 | |
492dfb48 | 940 | if (q && depth > q->nr_requests * 2) { |
1da177e4 LT |
941 | depth = q->nr_requests * 2; |
942 | printk(KERN_ERR "%s: adjusted depth to %d\n", | |
943 | __FUNCTION__, depth); | |
944 | } | |
945 | ||
f68110fc | 946 | tag_index = kzalloc(depth * sizeof(struct request *), GFP_ATOMIC); |
1da177e4 LT |
947 | if (!tag_index) |
948 | goto fail; | |
949 | ||
f7d37d02 | 950 | nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG; |
f68110fc | 951 | tag_map = kzalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC); |
1da177e4 LT |
952 | if (!tag_map) |
953 | goto fail; | |
954 | ||
ba025082 | 955 | tags->real_max_depth = depth; |
1da177e4 | 956 | tags->max_depth = depth; |
1da177e4 LT |
957 | tags->tag_index = tag_index; |
958 | tags->tag_map = tag_map; | |
959 | ||
1da177e4 LT |
960 | return 0; |
961 | fail: | |
962 | kfree(tag_index); | |
963 | return -ENOMEM; | |
964 | } | |
965 | ||
492dfb48 JB |
966 | static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q, |
967 | int depth) | |
968 | { | |
969 | struct blk_queue_tag *tags; | |
970 | ||
971 | tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC); | |
972 | if (!tags) | |
973 | goto fail; | |
974 | ||
975 | if (init_tag_map(q, tags, depth)) | |
976 | goto fail; | |
977 | ||
978 | INIT_LIST_HEAD(&tags->busy_list); | |
979 | tags->busy = 0; | |
980 | atomic_set(&tags->refcnt, 1); | |
981 | return tags; | |
982 | fail: | |
983 | kfree(tags); | |
984 | return NULL; | |
985 | } | |
986 | ||
987 | /** | |
988 | * blk_init_tags - initialize the tag info for an external tag map | |
989 | * @depth: the maximum queue depth supported | |
990 | * @tags: the tag to use | |
991 | **/ | |
992 | struct blk_queue_tag *blk_init_tags(int depth) | |
993 | { | |
994 | return __blk_queue_init_tags(NULL, depth); | |
995 | } | |
996 | EXPORT_SYMBOL(blk_init_tags); | |
997 | ||
1da177e4 LT |
998 | /** |
999 | * blk_queue_init_tags - initialize the queue tag info | |
1000 | * @q: the request queue for the device | |
1001 | * @depth: the maximum queue depth supported | |
1002 | * @tags: the tag to use | |
1003 | **/ | |
1004 | int blk_queue_init_tags(request_queue_t *q, int depth, | |
1005 | struct blk_queue_tag *tags) | |
1006 | { | |
1007 | int rc; | |
1008 | ||
1009 | BUG_ON(tags && q->queue_tags && tags != q->queue_tags); | |
1010 | ||
1011 | if (!tags && !q->queue_tags) { | |
492dfb48 | 1012 | tags = __blk_queue_init_tags(q, depth); |
1da177e4 | 1013 | |
492dfb48 | 1014 | if (!tags) |
1da177e4 | 1015 | goto fail; |
1da177e4 LT |
1016 | } else if (q->queue_tags) { |
1017 | if ((rc = blk_queue_resize_tags(q, depth))) | |
1018 | return rc; | |
1019 | set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); | |
1020 | return 0; | |
1021 | } else | |
1022 | atomic_inc(&tags->refcnt); | |
1023 | ||
1024 | /* | |
1025 | * assign it, all done | |
1026 | */ | |
1027 | q->queue_tags = tags; | |
1028 | q->queue_flags |= (1 << QUEUE_FLAG_QUEUED); | |
1029 | return 0; | |
1030 | fail: | |
1031 | kfree(tags); | |
1032 | return -ENOMEM; | |
1033 | } | |
1034 | ||
1035 | EXPORT_SYMBOL(blk_queue_init_tags); | |
1036 | ||
1037 | /** | |
1038 | * blk_queue_resize_tags - change the queueing depth | |
1039 | * @q: the request queue for the device | |
1040 | * @new_depth: the new max command queueing depth | |
1041 | * | |
1042 | * Notes: | |
1043 | * Must be called with the queue lock held. | |
1044 | **/ | |
1045 | int blk_queue_resize_tags(request_queue_t *q, int new_depth) | |
1046 | { | |
1047 | struct blk_queue_tag *bqt = q->queue_tags; | |
1048 | struct request **tag_index; | |
1049 | unsigned long *tag_map; | |
fa72b903 | 1050 | int max_depth, nr_ulongs; |
1da177e4 LT |
1051 | |
1052 | if (!bqt) | |
1053 | return -ENXIO; | |
1054 | ||
ba025082 TH |
1055 | /* |
1056 | * if we already have large enough real_max_depth. just | |
1057 | * adjust max_depth. *NOTE* as requests with tag value | |
1058 | * between new_depth and real_max_depth can be in-flight, tag | |
1059 | * map can not be shrunk blindly here. | |
1060 | */ | |
1061 | if (new_depth <= bqt->real_max_depth) { | |
1062 | bqt->max_depth = new_depth; | |
1063 | return 0; | |
1064 | } | |
1065 | ||
492dfb48 JB |
1066 | /* |
1067 | * Currently cannot replace a shared tag map with a new | |
1068 | * one, so error out if this is the case | |
1069 | */ | |
1070 | if (atomic_read(&bqt->refcnt) != 1) | |
1071 | return -EBUSY; | |
1072 | ||
1da177e4 LT |
1073 | /* |
1074 | * save the old state info, so we can copy it back | |
1075 | */ | |
1076 | tag_index = bqt->tag_index; | |
1077 | tag_map = bqt->tag_map; | |
ba025082 | 1078 | max_depth = bqt->real_max_depth; |
1da177e4 LT |
1079 | |
1080 | if (init_tag_map(q, bqt, new_depth)) | |
1081 | return -ENOMEM; | |
1082 | ||
1083 | memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *)); | |
f7d37d02 | 1084 | nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG; |
fa72b903 | 1085 | memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long)); |
1da177e4 LT |
1086 | |
1087 | kfree(tag_index); | |
1088 | kfree(tag_map); | |
1089 | return 0; | |
1090 | } | |
1091 | ||
1092 | EXPORT_SYMBOL(blk_queue_resize_tags); | |
1093 | ||
1094 | /** | |
1095 | * blk_queue_end_tag - end tag operations for a request | |
1096 | * @q: the request queue for the device | |
1097 | * @rq: the request that has completed | |
1098 | * | |
1099 | * Description: | |
1100 | * Typically called when end_that_request_first() returns 0, meaning | |
1101 | * all transfers have been done for a request. It's important to call | |
1102 | * this function before end_that_request_last(), as that will put the | |
1103 | * request back on the free list thus corrupting the internal tag list. | |
1104 | * | |
1105 | * Notes: | |
1106 | * queue lock must be held. | |
1107 | **/ | |
1108 | void blk_queue_end_tag(request_queue_t *q, struct request *rq) | |
1109 | { | |
1110 | struct blk_queue_tag *bqt = q->queue_tags; | |
1111 | int tag = rq->tag; | |
1112 | ||
1113 | BUG_ON(tag == -1); | |
1114 | ||
ba025082 | 1115 | if (unlikely(tag >= bqt->real_max_depth)) |
040c928c TH |
1116 | /* |
1117 | * This can happen after tag depth has been reduced. | |
1118 | * FIXME: how about a warning or info message here? | |
1119 | */ | |
1da177e4 LT |
1120 | return; |
1121 | ||
1122 | if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) { | |
040c928c TH |
1123 | printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n", |
1124 | __FUNCTION__, tag); | |
1da177e4 LT |
1125 | return; |
1126 | } | |
1127 | ||
1128 | list_del_init(&rq->queuelist); | |
4aff5e23 | 1129 | rq->cmd_flags &= ~REQ_QUEUED; |
1da177e4 LT |
1130 | rq->tag = -1; |
1131 | ||
1132 | if (unlikely(bqt->tag_index[tag] == NULL)) | |
040c928c TH |
1133 | printk(KERN_ERR "%s: tag %d is missing\n", |
1134 | __FUNCTION__, tag); | |
1da177e4 LT |
1135 | |
1136 | bqt->tag_index[tag] = NULL; | |
1137 | bqt->busy--; | |
1138 | } | |
1139 | ||
1140 | EXPORT_SYMBOL(blk_queue_end_tag); | |
1141 | ||
1142 | /** | |
1143 | * blk_queue_start_tag - find a free tag and assign it | |
1144 | * @q: the request queue for the device | |
1145 | * @rq: the block request that needs tagging | |
1146 | * | |
1147 | * Description: | |
1148 | * This can either be used as a stand-alone helper, or possibly be | |
1149 | * assigned as the queue &prep_rq_fn (in which case &struct request | |
1150 | * automagically gets a tag assigned). Note that this function | |
1151 | * assumes that any type of request can be queued! if this is not | |
1152 | * true for your device, you must check the request type before | |
1153 | * calling this function. The request will also be removed from | |
1154 | * the request queue, so it's the drivers responsibility to readd | |
1155 | * it if it should need to be restarted for some reason. | |
1156 | * | |
1157 | * Notes: | |
1158 | * queue lock must be held. | |
1159 | **/ | |
1160 | int blk_queue_start_tag(request_queue_t *q, struct request *rq) | |
1161 | { | |
1162 | struct blk_queue_tag *bqt = q->queue_tags; | |
2bf0fdad | 1163 | int tag; |
1da177e4 | 1164 | |
4aff5e23 | 1165 | if (unlikely((rq->cmd_flags & REQ_QUEUED))) { |
1da177e4 | 1166 | printk(KERN_ERR |
040c928c TH |
1167 | "%s: request %p for device [%s] already tagged %d", |
1168 | __FUNCTION__, rq, | |
1169 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag); | |
1da177e4 LT |
1170 | BUG(); |
1171 | } | |
1172 | ||
2bf0fdad TH |
1173 | tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth); |
1174 | if (tag >= bqt->max_depth) | |
1175 | return 1; | |
1da177e4 | 1176 | |
1da177e4 LT |
1177 | __set_bit(tag, bqt->tag_map); |
1178 | ||
4aff5e23 | 1179 | rq->cmd_flags |= REQ_QUEUED; |
1da177e4 LT |
1180 | rq->tag = tag; |
1181 | bqt->tag_index[tag] = rq; | |
1182 | blkdev_dequeue_request(rq); | |
1183 | list_add(&rq->queuelist, &bqt->busy_list); | |
1184 | bqt->busy++; | |
1185 | return 0; | |
1186 | } | |
1187 | ||
1188 | EXPORT_SYMBOL(blk_queue_start_tag); | |
1189 | ||
1190 | /** | |
1191 | * blk_queue_invalidate_tags - invalidate all pending tags | |
1192 | * @q: the request queue for the device | |
1193 | * | |
1194 | * Description: | |
1195 | * Hardware conditions may dictate a need to stop all pending requests. | |
1196 | * In this case, we will safely clear the block side of the tag queue and | |
1197 | * readd all requests to the request queue in the right order. | |
1198 | * | |
1199 | * Notes: | |
1200 | * queue lock must be held. | |
1201 | **/ | |
1202 | void blk_queue_invalidate_tags(request_queue_t *q) | |
1203 | { | |
1204 | struct blk_queue_tag *bqt = q->queue_tags; | |
1205 | struct list_head *tmp, *n; | |
1206 | struct request *rq; | |
1207 | ||
1208 | list_for_each_safe(tmp, n, &bqt->busy_list) { | |
1209 | rq = list_entry_rq(tmp); | |
1210 | ||
1211 | if (rq->tag == -1) { | |
040c928c TH |
1212 | printk(KERN_ERR |
1213 | "%s: bad tag found on list\n", __FUNCTION__); | |
1da177e4 | 1214 | list_del_init(&rq->queuelist); |
4aff5e23 | 1215 | rq->cmd_flags &= ~REQ_QUEUED; |
1da177e4 LT |
1216 | } else |
1217 | blk_queue_end_tag(q, rq); | |
1218 | ||
4aff5e23 | 1219 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 LT |
1220 | __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); |
1221 | } | |
1222 | } | |
1223 | ||
1224 | EXPORT_SYMBOL(blk_queue_invalidate_tags); | |
1225 | ||
1da177e4 LT |
1226 | void blk_dump_rq_flags(struct request *rq, char *msg) |
1227 | { | |
1228 | int bit; | |
1229 | ||
4aff5e23 JA |
1230 | printk("%s: dev %s: type=%x, flags=%x\n", msg, |
1231 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, | |
1232 | rq->cmd_flags); | |
1da177e4 LT |
1233 | |
1234 | printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector, | |
1235 | rq->nr_sectors, | |
1236 | rq->current_nr_sectors); | |
1237 | printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len); | |
1238 | ||
4aff5e23 | 1239 | if (blk_pc_request(rq)) { |
1da177e4 LT |
1240 | printk("cdb: "); |
1241 | for (bit = 0; bit < sizeof(rq->cmd); bit++) | |
1242 | printk("%02x ", rq->cmd[bit]); | |
1243 | printk("\n"); | |
1244 | } | |
1245 | } | |
1246 | ||
1247 | EXPORT_SYMBOL(blk_dump_rq_flags); | |
1248 | ||
1249 | void blk_recount_segments(request_queue_t *q, struct bio *bio) | |
1250 | { | |
1251 | struct bio_vec *bv, *bvprv = NULL; | |
1252 | int i, nr_phys_segs, nr_hw_segs, seg_size, hw_seg_size, cluster; | |
1253 | int high, highprv = 1; | |
1254 | ||
1255 | if (unlikely(!bio->bi_io_vec)) | |
1256 | return; | |
1257 | ||
1258 | cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); | |
1259 | hw_seg_size = seg_size = nr_phys_segs = nr_hw_segs = 0; | |
1260 | bio_for_each_segment(bv, bio, i) { | |
1261 | /* | |
1262 | * the trick here is making sure that a high page is never | |
1263 | * considered part of another segment, since that might | |
1264 | * change with the bounce page. | |
1265 | */ | |
1266 | high = page_to_pfn(bv->bv_page) >= q->bounce_pfn; | |
1267 | if (high || highprv) | |
1268 | goto new_hw_segment; | |
1269 | if (cluster) { | |
1270 | if (seg_size + bv->bv_len > q->max_segment_size) | |
1271 | goto new_segment; | |
1272 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv)) | |
1273 | goto new_segment; | |
1274 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv)) | |
1275 | goto new_segment; | |
1276 | if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) | |
1277 | goto new_hw_segment; | |
1278 | ||
1279 | seg_size += bv->bv_len; | |
1280 | hw_seg_size += bv->bv_len; | |
1281 | bvprv = bv; | |
1282 | continue; | |
1283 | } | |
1284 | new_segment: | |
1285 | if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) && | |
1286 | !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) { | |
1287 | hw_seg_size += bv->bv_len; | |
1288 | } else { | |
1289 | new_hw_segment: | |
1290 | if (hw_seg_size > bio->bi_hw_front_size) | |
1291 | bio->bi_hw_front_size = hw_seg_size; | |
1292 | hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len; | |
1293 | nr_hw_segs++; | |
1294 | } | |
1295 | ||
1296 | nr_phys_segs++; | |
1297 | bvprv = bv; | |
1298 | seg_size = bv->bv_len; | |
1299 | highprv = high; | |
1300 | } | |
1301 | if (hw_seg_size > bio->bi_hw_back_size) | |
1302 | bio->bi_hw_back_size = hw_seg_size; | |
1303 | if (nr_hw_segs == 1 && hw_seg_size > bio->bi_hw_front_size) | |
1304 | bio->bi_hw_front_size = hw_seg_size; | |
1305 | bio->bi_phys_segments = nr_phys_segs; | |
1306 | bio->bi_hw_segments = nr_hw_segs; | |
1307 | bio->bi_flags |= (1 << BIO_SEG_VALID); | |
1308 | } | |
1309 | ||
1310 | ||
93d17d3d | 1311 | static int blk_phys_contig_segment(request_queue_t *q, struct bio *bio, |
1da177e4 LT |
1312 | struct bio *nxt) |
1313 | { | |
1314 | if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER))) | |
1315 | return 0; | |
1316 | ||
1317 | if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt))) | |
1318 | return 0; | |
1319 | if (bio->bi_size + nxt->bi_size > q->max_segment_size) | |
1320 | return 0; | |
1321 | ||
1322 | /* | |
1323 | * bio and nxt are contigous in memory, check if the queue allows | |
1324 | * these two to be merged into one | |
1325 | */ | |
1326 | if (BIO_SEG_BOUNDARY(q, bio, nxt)) | |
1327 | return 1; | |
1328 | ||
1329 | return 0; | |
1330 | } | |
1331 | ||
93d17d3d | 1332 | static int blk_hw_contig_segment(request_queue_t *q, struct bio *bio, |
1da177e4 LT |
1333 | struct bio *nxt) |
1334 | { | |
1335 | if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
1336 | blk_recount_segments(q, bio); | |
1337 | if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID))) | |
1338 | blk_recount_segments(q, nxt); | |
1339 | if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) || | |
1340 | BIOVEC_VIRT_OVERSIZE(bio->bi_hw_front_size + bio->bi_hw_back_size)) | |
1341 | return 0; | |
1342 | if (bio->bi_size + nxt->bi_size > q->max_segment_size) | |
1343 | return 0; | |
1344 | ||
1345 | return 1; | |
1346 | } | |
1347 | ||
1da177e4 LT |
1348 | /* |
1349 | * map a request to scatterlist, return number of sg entries setup. Caller | |
1350 | * must make sure sg can hold rq->nr_phys_segments entries | |
1351 | */ | |
1352 | int blk_rq_map_sg(request_queue_t *q, struct request *rq, struct scatterlist *sg) | |
1353 | { | |
1354 | struct bio_vec *bvec, *bvprv; | |
1355 | struct bio *bio; | |
1356 | int nsegs, i, cluster; | |
1357 | ||
1358 | nsegs = 0; | |
1359 | cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); | |
1360 | ||
1361 | /* | |
1362 | * for each bio in rq | |
1363 | */ | |
1364 | bvprv = NULL; | |
1365 | rq_for_each_bio(bio, rq) { | |
1366 | /* | |
1367 | * for each segment in bio | |
1368 | */ | |
1369 | bio_for_each_segment(bvec, bio, i) { | |
1370 | int nbytes = bvec->bv_len; | |
1371 | ||
1372 | if (bvprv && cluster) { | |
1373 | if (sg[nsegs - 1].length + nbytes > q->max_segment_size) | |
1374 | goto new_segment; | |
1375 | ||
1376 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) | |
1377 | goto new_segment; | |
1378 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) | |
1379 | goto new_segment; | |
1380 | ||
1381 | sg[nsegs - 1].length += nbytes; | |
1382 | } else { | |
1383 | new_segment: | |
1384 | memset(&sg[nsegs],0,sizeof(struct scatterlist)); | |
1385 | sg[nsegs].page = bvec->bv_page; | |
1386 | sg[nsegs].length = nbytes; | |
1387 | sg[nsegs].offset = bvec->bv_offset; | |
1388 | ||
1389 | nsegs++; | |
1390 | } | |
1391 | bvprv = bvec; | |
1392 | } /* segments in bio */ | |
1393 | } /* bios in rq */ | |
1394 | ||
1395 | return nsegs; | |
1396 | } | |
1397 | ||
1398 | EXPORT_SYMBOL(blk_rq_map_sg); | |
1399 | ||
1400 | /* | |
1401 | * the standard queue merge functions, can be overridden with device | |
1402 | * specific ones if so desired | |
1403 | */ | |
1404 | ||
1405 | static inline int ll_new_mergeable(request_queue_t *q, | |
1406 | struct request *req, | |
1407 | struct bio *bio) | |
1408 | { | |
1409 | int nr_phys_segs = bio_phys_segments(q, bio); | |
1410 | ||
1411 | if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { | |
4aff5e23 | 1412 | req->cmd_flags |= REQ_NOMERGE; |
1da177e4 LT |
1413 | if (req == q->last_merge) |
1414 | q->last_merge = NULL; | |
1415 | return 0; | |
1416 | } | |
1417 | ||
1418 | /* | |
1419 | * A hw segment is just getting larger, bump just the phys | |
1420 | * counter. | |
1421 | */ | |
1422 | req->nr_phys_segments += nr_phys_segs; | |
1423 | return 1; | |
1424 | } | |
1425 | ||
1426 | static inline int ll_new_hw_segment(request_queue_t *q, | |
1427 | struct request *req, | |
1428 | struct bio *bio) | |
1429 | { | |
1430 | int nr_hw_segs = bio_hw_segments(q, bio); | |
1431 | int nr_phys_segs = bio_phys_segments(q, bio); | |
1432 | ||
1433 | if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments | |
1434 | || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { | |
4aff5e23 | 1435 | req->cmd_flags |= REQ_NOMERGE; |
1da177e4 LT |
1436 | if (req == q->last_merge) |
1437 | q->last_merge = NULL; | |
1438 | return 0; | |
1439 | } | |
1440 | ||
1441 | /* | |
1442 | * This will form the start of a new hw segment. Bump both | |
1443 | * counters. | |
1444 | */ | |
1445 | req->nr_hw_segments += nr_hw_segs; | |
1446 | req->nr_phys_segments += nr_phys_segs; | |
1447 | return 1; | |
1448 | } | |
1449 | ||
1450 | static int ll_back_merge_fn(request_queue_t *q, struct request *req, | |
1451 | struct bio *bio) | |
1452 | { | |
defd94b7 | 1453 | unsigned short max_sectors; |
1da177e4 LT |
1454 | int len; |
1455 | ||
defd94b7 MC |
1456 | if (unlikely(blk_pc_request(req))) |
1457 | max_sectors = q->max_hw_sectors; | |
1458 | else | |
1459 | max_sectors = q->max_sectors; | |
1460 | ||
1461 | if (req->nr_sectors + bio_sectors(bio) > max_sectors) { | |
4aff5e23 | 1462 | req->cmd_flags |= REQ_NOMERGE; |
1da177e4 LT |
1463 | if (req == q->last_merge) |
1464 | q->last_merge = NULL; | |
1465 | return 0; | |
1466 | } | |
1467 | if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID))) | |
1468 | blk_recount_segments(q, req->biotail); | |
1469 | if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
1470 | blk_recount_segments(q, bio); | |
1471 | len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size; | |
1472 | if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) && | |
1473 | !BIOVEC_VIRT_OVERSIZE(len)) { | |
1474 | int mergeable = ll_new_mergeable(q, req, bio); | |
1475 | ||
1476 | if (mergeable) { | |
1477 | if (req->nr_hw_segments == 1) | |
1478 | req->bio->bi_hw_front_size = len; | |
1479 | if (bio->bi_hw_segments == 1) | |
1480 | bio->bi_hw_back_size = len; | |
1481 | } | |
1482 | return mergeable; | |
1483 | } | |
1484 | ||
1485 | return ll_new_hw_segment(q, req, bio); | |
1486 | } | |
1487 | ||
1488 | static int ll_front_merge_fn(request_queue_t *q, struct request *req, | |
1489 | struct bio *bio) | |
1490 | { | |
defd94b7 | 1491 | unsigned short max_sectors; |
1da177e4 LT |
1492 | int len; |
1493 | ||
defd94b7 MC |
1494 | if (unlikely(blk_pc_request(req))) |
1495 | max_sectors = q->max_hw_sectors; | |
1496 | else | |
1497 | max_sectors = q->max_sectors; | |
1498 | ||
1499 | ||
1500 | if (req->nr_sectors + bio_sectors(bio) > max_sectors) { | |
4aff5e23 | 1501 | req->cmd_flags |= REQ_NOMERGE; |
1da177e4 LT |
1502 | if (req == q->last_merge) |
1503 | q->last_merge = NULL; | |
1504 | return 0; | |
1505 | } | |
1506 | len = bio->bi_hw_back_size + req->bio->bi_hw_front_size; | |
1507 | if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
1508 | blk_recount_segments(q, bio); | |
1509 | if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID))) | |
1510 | blk_recount_segments(q, req->bio); | |
1511 | if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) && | |
1512 | !BIOVEC_VIRT_OVERSIZE(len)) { | |
1513 | int mergeable = ll_new_mergeable(q, req, bio); | |
1514 | ||
1515 | if (mergeable) { | |
1516 | if (bio->bi_hw_segments == 1) | |
1517 | bio->bi_hw_front_size = len; | |
1518 | if (req->nr_hw_segments == 1) | |
1519 | req->biotail->bi_hw_back_size = len; | |
1520 | } | |
1521 | return mergeable; | |
1522 | } | |
1523 | ||
1524 | return ll_new_hw_segment(q, req, bio); | |
1525 | } | |
1526 | ||
1527 | static int ll_merge_requests_fn(request_queue_t *q, struct request *req, | |
1528 | struct request *next) | |
1529 | { | |
dfa1a553 ND |
1530 | int total_phys_segments; |
1531 | int total_hw_segments; | |
1da177e4 LT |
1532 | |
1533 | /* | |
1534 | * First check if the either of the requests are re-queued | |
1535 | * requests. Can't merge them if they are. | |
1536 | */ | |
1537 | if (req->special || next->special) | |
1538 | return 0; | |
1539 | ||
1540 | /* | |
dfa1a553 | 1541 | * Will it become too large? |
1da177e4 LT |
1542 | */ |
1543 | if ((req->nr_sectors + next->nr_sectors) > q->max_sectors) | |
1544 | return 0; | |
1545 | ||
1546 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
1547 | if (blk_phys_contig_segment(q, req->biotail, next->bio)) | |
1548 | total_phys_segments--; | |
1549 | ||
1550 | if (total_phys_segments > q->max_phys_segments) | |
1551 | return 0; | |
1552 | ||
1553 | total_hw_segments = req->nr_hw_segments + next->nr_hw_segments; | |
1554 | if (blk_hw_contig_segment(q, req->biotail, next->bio)) { | |
1555 | int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size; | |
1556 | /* | |
1557 | * propagate the combined length to the end of the requests | |
1558 | */ | |
1559 | if (req->nr_hw_segments == 1) | |
1560 | req->bio->bi_hw_front_size = len; | |
1561 | if (next->nr_hw_segments == 1) | |
1562 | next->biotail->bi_hw_back_size = len; | |
1563 | total_hw_segments--; | |
1564 | } | |
1565 | ||
1566 | if (total_hw_segments > q->max_hw_segments) | |
1567 | return 0; | |
1568 | ||
1569 | /* Merge is OK... */ | |
1570 | req->nr_phys_segments = total_phys_segments; | |
1571 | req->nr_hw_segments = total_hw_segments; | |
1572 | return 1; | |
1573 | } | |
1574 | ||
1575 | /* | |
1576 | * "plug" the device if there are no outstanding requests: this will | |
1577 | * force the transfer to start only after we have put all the requests | |
1578 | * on the list. | |
1579 | * | |
1580 | * This is called with interrupts off and no requests on the queue and | |
1581 | * with the queue lock held. | |
1582 | */ | |
1583 | void blk_plug_device(request_queue_t *q) | |
1584 | { | |
1585 | WARN_ON(!irqs_disabled()); | |
1586 | ||
1587 | /* | |
1588 | * don't plug a stopped queue, it must be paired with blk_start_queue() | |
1589 | * which will restart the queueing | |
1590 | */ | |
7daac490 | 1591 | if (blk_queue_stopped(q)) |
1da177e4 LT |
1592 | return; |
1593 | ||
2056a782 | 1594 | if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) { |
1da177e4 | 1595 | mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); |
2056a782 JA |
1596 | blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG); |
1597 | } | |
1da177e4 LT |
1598 | } |
1599 | ||
1600 | EXPORT_SYMBOL(blk_plug_device); | |
1601 | ||
1602 | /* | |
1603 | * remove the queue from the plugged list, if present. called with | |
1604 | * queue lock held and interrupts disabled. | |
1605 | */ | |
1606 | int blk_remove_plug(request_queue_t *q) | |
1607 | { | |
1608 | WARN_ON(!irqs_disabled()); | |
1609 | ||
1610 | if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) | |
1611 | return 0; | |
1612 | ||
1613 | del_timer(&q->unplug_timer); | |
1614 | return 1; | |
1615 | } | |
1616 | ||
1617 | EXPORT_SYMBOL(blk_remove_plug); | |
1618 | ||
1619 | /* | |
1620 | * remove the plug and let it rip.. | |
1621 | */ | |
1622 | void __generic_unplug_device(request_queue_t *q) | |
1623 | { | |
7daac490 | 1624 | if (unlikely(blk_queue_stopped(q))) |
1da177e4 LT |
1625 | return; |
1626 | ||
1627 | if (!blk_remove_plug(q)) | |
1628 | return; | |
1629 | ||
22e2c507 | 1630 | q->request_fn(q); |
1da177e4 LT |
1631 | } |
1632 | EXPORT_SYMBOL(__generic_unplug_device); | |
1633 | ||
1634 | /** | |
1635 | * generic_unplug_device - fire a request queue | |
1636 | * @q: The &request_queue_t in question | |
1637 | * | |
1638 | * Description: | |
1639 | * Linux uses plugging to build bigger requests queues before letting | |
1640 | * the device have at them. If a queue is plugged, the I/O scheduler | |
1641 | * is still adding and merging requests on the queue. Once the queue | |
1642 | * gets unplugged, the request_fn defined for the queue is invoked and | |
1643 | * transfers started. | |
1644 | **/ | |
1645 | void generic_unplug_device(request_queue_t *q) | |
1646 | { | |
1647 | spin_lock_irq(q->queue_lock); | |
1648 | __generic_unplug_device(q); | |
1649 | spin_unlock_irq(q->queue_lock); | |
1650 | } | |
1651 | EXPORT_SYMBOL(generic_unplug_device); | |
1652 | ||
1653 | static void blk_backing_dev_unplug(struct backing_dev_info *bdi, | |
1654 | struct page *page) | |
1655 | { | |
1656 | request_queue_t *q = bdi->unplug_io_data; | |
1657 | ||
1658 | /* | |
1659 | * devices don't necessarily have an ->unplug_fn defined | |
1660 | */ | |
2056a782 JA |
1661 | if (q->unplug_fn) { |
1662 | blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, | |
1663 | q->rq.count[READ] + q->rq.count[WRITE]); | |
1664 | ||
1da177e4 | 1665 | q->unplug_fn(q); |
2056a782 | 1666 | } |
1da177e4 LT |
1667 | } |
1668 | ||
1669 | static void blk_unplug_work(void *data) | |
1670 | { | |
1671 | request_queue_t *q = data; | |
1672 | ||
2056a782 JA |
1673 | blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, |
1674 | q->rq.count[READ] + q->rq.count[WRITE]); | |
1675 | ||
1da177e4 LT |
1676 | q->unplug_fn(q); |
1677 | } | |
1678 | ||
1679 | static void blk_unplug_timeout(unsigned long data) | |
1680 | { | |
1681 | request_queue_t *q = (request_queue_t *)data; | |
1682 | ||
2056a782 JA |
1683 | blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL, |
1684 | q->rq.count[READ] + q->rq.count[WRITE]); | |
1685 | ||
1da177e4 LT |
1686 | kblockd_schedule_work(&q->unplug_work); |
1687 | } | |
1688 | ||
1689 | /** | |
1690 | * blk_start_queue - restart a previously stopped queue | |
1691 | * @q: The &request_queue_t in question | |
1692 | * | |
1693 | * Description: | |
1694 | * blk_start_queue() will clear the stop flag on the queue, and call | |
1695 | * the request_fn for the queue if it was in a stopped state when | |
1696 | * entered. Also see blk_stop_queue(). Queue lock must be held. | |
1697 | **/ | |
1698 | void blk_start_queue(request_queue_t *q) | |
1699 | { | |
a038e253 PBG |
1700 | WARN_ON(!irqs_disabled()); |
1701 | ||
1da177e4 LT |
1702 | clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); |
1703 | ||
1704 | /* | |
1705 | * one level of recursion is ok and is much faster than kicking | |
1706 | * the unplug handling | |
1707 | */ | |
1708 | if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { | |
1709 | q->request_fn(q); | |
1710 | clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); | |
1711 | } else { | |
1712 | blk_plug_device(q); | |
1713 | kblockd_schedule_work(&q->unplug_work); | |
1714 | } | |
1715 | } | |
1716 | ||
1717 | EXPORT_SYMBOL(blk_start_queue); | |
1718 | ||
1719 | /** | |
1720 | * blk_stop_queue - stop a queue | |
1721 | * @q: The &request_queue_t in question | |
1722 | * | |
1723 | * Description: | |
1724 | * The Linux block layer assumes that a block driver will consume all | |
1725 | * entries on the request queue when the request_fn strategy is called. | |
1726 | * Often this will not happen, because of hardware limitations (queue | |
1727 | * depth settings). If a device driver gets a 'queue full' response, | |
1728 | * or if it simply chooses not to queue more I/O at one point, it can | |
1729 | * call this function to prevent the request_fn from being called until | |
1730 | * the driver has signalled it's ready to go again. This happens by calling | |
1731 | * blk_start_queue() to restart queue operations. Queue lock must be held. | |
1732 | **/ | |
1733 | void blk_stop_queue(request_queue_t *q) | |
1734 | { | |
1735 | blk_remove_plug(q); | |
1736 | set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); | |
1737 | } | |
1738 | EXPORT_SYMBOL(blk_stop_queue); | |
1739 | ||
1740 | /** | |
1741 | * blk_sync_queue - cancel any pending callbacks on a queue | |
1742 | * @q: the queue | |
1743 | * | |
1744 | * Description: | |
1745 | * The block layer may perform asynchronous callback activity | |
1746 | * on a queue, such as calling the unplug function after a timeout. | |
1747 | * A block device may call blk_sync_queue to ensure that any | |
1748 | * such activity is cancelled, thus allowing it to release resources | |
1749 | * the the callbacks might use. The caller must already have made sure | |
1750 | * that its ->make_request_fn will not re-add plugging prior to calling | |
1751 | * this function. | |
1752 | * | |
1753 | */ | |
1754 | void blk_sync_queue(struct request_queue *q) | |
1755 | { | |
1756 | del_timer_sync(&q->unplug_timer); | |
1757 | kblockd_flush(); | |
1758 | } | |
1759 | EXPORT_SYMBOL(blk_sync_queue); | |
1760 | ||
1761 | /** | |
1762 | * blk_run_queue - run a single device queue | |
1763 | * @q: The queue to run | |
1764 | */ | |
1765 | void blk_run_queue(struct request_queue *q) | |
1766 | { | |
1767 | unsigned long flags; | |
1768 | ||
1769 | spin_lock_irqsave(q->queue_lock, flags); | |
1770 | blk_remove_plug(q); | |
dac07ec1 JA |
1771 | |
1772 | /* | |
1773 | * Only recurse once to avoid overrunning the stack, let the unplug | |
1774 | * handling reinvoke the handler shortly if we already got there. | |
1775 | */ | |
1776 | if (!elv_queue_empty(q)) { | |
1777 | if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { | |
1778 | q->request_fn(q); | |
1779 | clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); | |
1780 | } else { | |
1781 | blk_plug_device(q); | |
1782 | kblockd_schedule_work(&q->unplug_work); | |
1783 | } | |
1784 | } | |
1785 | ||
1da177e4 LT |
1786 | spin_unlock_irqrestore(q->queue_lock, flags); |
1787 | } | |
1788 | EXPORT_SYMBOL(blk_run_queue); | |
1789 | ||
1790 | /** | |
1791 | * blk_cleanup_queue: - release a &request_queue_t when it is no longer needed | |
a580290c | 1792 | * @kobj: the kobj belonging of the request queue to be released |
1da177e4 LT |
1793 | * |
1794 | * Description: | |
1795 | * blk_cleanup_queue is the pair to blk_init_queue() or | |
1796 | * blk_queue_make_request(). It should be called when a request queue is | |
1797 | * being released; typically when a block device is being de-registered. | |
1798 | * Currently, its primary task it to free all the &struct request | |
1799 | * structures that were allocated to the queue and the queue itself. | |
1800 | * | |
1801 | * Caveat: | |
1802 | * Hopefully the low level driver will have finished any | |
1803 | * outstanding requests first... | |
1804 | **/ | |
483f4afc | 1805 | static void blk_release_queue(struct kobject *kobj) |
1da177e4 | 1806 | { |
483f4afc | 1807 | request_queue_t *q = container_of(kobj, struct request_queue, kobj); |
1da177e4 LT |
1808 | struct request_list *rl = &q->rq; |
1809 | ||
1da177e4 LT |
1810 | blk_sync_queue(q); |
1811 | ||
1812 | if (rl->rq_pool) | |
1813 | mempool_destroy(rl->rq_pool); | |
1814 | ||
1815 | if (q->queue_tags) | |
1816 | __blk_queue_free_tags(q); | |
1817 | ||
6c5c9341 | 1818 | blk_trace_shutdown(q); |
2056a782 | 1819 | |
1da177e4 LT |
1820 | kmem_cache_free(requestq_cachep, q); |
1821 | } | |
1822 | ||
483f4afc AV |
1823 | void blk_put_queue(request_queue_t *q) |
1824 | { | |
1825 | kobject_put(&q->kobj); | |
1826 | } | |
1827 | EXPORT_SYMBOL(blk_put_queue); | |
1828 | ||
1829 | void blk_cleanup_queue(request_queue_t * q) | |
1830 | { | |
1831 | mutex_lock(&q->sysfs_lock); | |
1832 | set_bit(QUEUE_FLAG_DEAD, &q->queue_flags); | |
1833 | mutex_unlock(&q->sysfs_lock); | |
1834 | ||
1835 | if (q->elevator) | |
1836 | elevator_exit(q->elevator); | |
1837 | ||
1838 | blk_put_queue(q); | |
1839 | } | |
1840 | ||
1da177e4 LT |
1841 | EXPORT_SYMBOL(blk_cleanup_queue); |
1842 | ||
1843 | static int blk_init_free_list(request_queue_t *q) | |
1844 | { | |
1845 | struct request_list *rl = &q->rq; | |
1846 | ||
1847 | rl->count[READ] = rl->count[WRITE] = 0; | |
1848 | rl->starved[READ] = rl->starved[WRITE] = 0; | |
cb98fc8b | 1849 | rl->elvpriv = 0; |
1da177e4 LT |
1850 | init_waitqueue_head(&rl->wait[READ]); |
1851 | init_waitqueue_head(&rl->wait[WRITE]); | |
1da177e4 | 1852 | |
1946089a CL |
1853 | rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
1854 | mempool_free_slab, request_cachep, q->node); | |
1da177e4 LT |
1855 | |
1856 | if (!rl->rq_pool) | |
1857 | return -ENOMEM; | |
1858 | ||
1859 | return 0; | |
1860 | } | |
1861 | ||
8267e268 | 1862 | request_queue_t *blk_alloc_queue(gfp_t gfp_mask) |
1da177e4 | 1863 | { |
1946089a CL |
1864 | return blk_alloc_queue_node(gfp_mask, -1); |
1865 | } | |
1866 | EXPORT_SYMBOL(blk_alloc_queue); | |
1da177e4 | 1867 | |
483f4afc AV |
1868 | static struct kobj_type queue_ktype; |
1869 | ||
8267e268 | 1870 | request_queue_t *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) |
1946089a CL |
1871 | { |
1872 | request_queue_t *q; | |
1873 | ||
1874 | q = kmem_cache_alloc_node(requestq_cachep, gfp_mask, node_id); | |
1da177e4 LT |
1875 | if (!q) |
1876 | return NULL; | |
1877 | ||
1878 | memset(q, 0, sizeof(*q)); | |
1879 | init_timer(&q->unplug_timer); | |
483f4afc AV |
1880 | |
1881 | snprintf(q->kobj.name, KOBJ_NAME_LEN, "%s", "queue"); | |
1882 | q->kobj.ktype = &queue_ktype; | |
1883 | kobject_init(&q->kobj); | |
1da177e4 LT |
1884 | |
1885 | q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; | |
1886 | q->backing_dev_info.unplug_io_data = q; | |
1887 | ||
483f4afc AV |
1888 | mutex_init(&q->sysfs_lock); |
1889 | ||
1da177e4 LT |
1890 | return q; |
1891 | } | |
1946089a | 1892 | EXPORT_SYMBOL(blk_alloc_queue_node); |
1da177e4 LT |
1893 | |
1894 | /** | |
1895 | * blk_init_queue - prepare a request queue for use with a block device | |
1896 | * @rfn: The function to be called to process requests that have been | |
1897 | * placed on the queue. | |
1898 | * @lock: Request queue spin lock | |
1899 | * | |
1900 | * Description: | |
1901 | * If a block device wishes to use the standard request handling procedures, | |
1902 | * which sorts requests and coalesces adjacent requests, then it must | |
1903 | * call blk_init_queue(). The function @rfn will be called when there | |
1904 | * are requests on the queue that need to be processed. If the device | |
1905 | * supports plugging, then @rfn may not be called immediately when requests | |
1906 | * are available on the queue, but may be called at some time later instead. | |
1907 | * Plugged queues are generally unplugged when a buffer belonging to one | |
1908 | * of the requests on the queue is needed, or due to memory pressure. | |
1909 | * | |
1910 | * @rfn is not required, or even expected, to remove all requests off the | |
1911 | * queue, but only as many as it can handle at a time. If it does leave | |
1912 | * requests on the queue, it is responsible for arranging that the requests | |
1913 | * get dealt with eventually. | |
1914 | * | |
1915 | * The queue spin lock must be held while manipulating the requests on the | |
a038e253 PBG |
1916 | * request queue; this lock will be taken also from interrupt context, so irq |
1917 | * disabling is needed for it. | |
1da177e4 LT |
1918 | * |
1919 | * Function returns a pointer to the initialized request queue, or NULL if | |
1920 | * it didn't succeed. | |
1921 | * | |
1922 | * Note: | |
1923 | * blk_init_queue() must be paired with a blk_cleanup_queue() call | |
1924 | * when the block device is deactivated (such as at module unload). | |
1925 | **/ | |
1946089a | 1926 | |
1da177e4 LT |
1927 | request_queue_t *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) |
1928 | { | |
1946089a CL |
1929 | return blk_init_queue_node(rfn, lock, -1); |
1930 | } | |
1931 | EXPORT_SYMBOL(blk_init_queue); | |
1932 | ||
1933 | request_queue_t * | |
1934 | blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) | |
1935 | { | |
1936 | request_queue_t *q = blk_alloc_queue_node(GFP_KERNEL, node_id); | |
1da177e4 LT |
1937 | |
1938 | if (!q) | |
1939 | return NULL; | |
1940 | ||
1946089a | 1941 | q->node = node_id; |
8669aafd AV |
1942 | if (blk_init_free_list(q)) { |
1943 | kmem_cache_free(requestq_cachep, q); | |
1944 | return NULL; | |
1945 | } | |
1da177e4 | 1946 | |
152587de JA |
1947 | /* |
1948 | * if caller didn't supply a lock, they get per-queue locking with | |
1949 | * our embedded lock | |
1950 | */ | |
1951 | if (!lock) { | |
1952 | spin_lock_init(&q->__queue_lock); | |
1953 | lock = &q->__queue_lock; | |
1954 | } | |
1955 | ||
1da177e4 LT |
1956 | q->request_fn = rfn; |
1957 | q->back_merge_fn = ll_back_merge_fn; | |
1958 | q->front_merge_fn = ll_front_merge_fn; | |
1959 | q->merge_requests_fn = ll_merge_requests_fn; | |
1960 | q->prep_rq_fn = NULL; | |
1961 | q->unplug_fn = generic_unplug_device; | |
1962 | q->queue_flags = (1 << QUEUE_FLAG_CLUSTER); | |
1963 | q->queue_lock = lock; | |
1964 | ||
1965 | blk_queue_segment_boundary(q, 0xffffffff); | |
1966 | ||
1967 | blk_queue_make_request(q, __make_request); | |
1968 | blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE); | |
1969 | ||
1970 | blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); | |
1971 | blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); | |
1972 | ||
1973 | /* | |
1974 | * all done | |
1975 | */ | |
1976 | if (!elevator_init(q, NULL)) { | |
1977 | blk_queue_congestion_threshold(q); | |
1978 | return q; | |
1979 | } | |
1980 | ||
8669aafd | 1981 | blk_put_queue(q); |
1da177e4 LT |
1982 | return NULL; |
1983 | } | |
1946089a | 1984 | EXPORT_SYMBOL(blk_init_queue_node); |
1da177e4 LT |
1985 | |
1986 | int blk_get_queue(request_queue_t *q) | |
1987 | { | |
fde6ad22 | 1988 | if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { |
483f4afc | 1989 | kobject_get(&q->kobj); |
1da177e4 LT |
1990 | return 0; |
1991 | } | |
1992 | ||
1993 | return 1; | |
1994 | } | |
1995 | ||
1996 | EXPORT_SYMBOL(blk_get_queue); | |
1997 | ||
1998 | static inline void blk_free_request(request_queue_t *q, struct request *rq) | |
1999 | { | |
4aff5e23 | 2000 | if (rq->cmd_flags & REQ_ELVPRIV) |
cb98fc8b | 2001 | elv_put_request(q, rq); |
1da177e4 LT |
2002 | mempool_free(rq, q->rq.rq_pool); |
2003 | } | |
2004 | ||
22e2c507 | 2005 | static inline struct request * |
cb78b285 | 2006 | blk_alloc_request(request_queue_t *q, int rw, int priv, gfp_t gfp_mask) |
1da177e4 LT |
2007 | { |
2008 | struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); | |
2009 | ||
2010 | if (!rq) | |
2011 | return NULL; | |
2012 | ||
2013 | /* | |
4aff5e23 | 2014 | * first three bits are identical in rq->cmd_flags and bio->bi_rw, |
1da177e4 LT |
2015 | * see bio.h and blkdev.h |
2016 | */ | |
49171e5c | 2017 | rq->cmd_flags = rw | REQ_ALLOCED; |
1da177e4 | 2018 | |
cb98fc8b | 2019 | if (priv) { |
cb78b285 | 2020 | if (unlikely(elv_set_request(q, rq, gfp_mask))) { |
cb98fc8b TH |
2021 | mempool_free(rq, q->rq.rq_pool); |
2022 | return NULL; | |
2023 | } | |
4aff5e23 | 2024 | rq->cmd_flags |= REQ_ELVPRIV; |
cb98fc8b | 2025 | } |
1da177e4 | 2026 | |
cb98fc8b | 2027 | return rq; |
1da177e4 LT |
2028 | } |
2029 | ||
2030 | /* | |
2031 | * ioc_batching returns true if the ioc is a valid batching request and | |
2032 | * should be given priority access to a request. | |
2033 | */ | |
2034 | static inline int ioc_batching(request_queue_t *q, struct io_context *ioc) | |
2035 | { | |
2036 | if (!ioc) | |
2037 | return 0; | |
2038 | ||
2039 | /* | |
2040 | * Make sure the process is able to allocate at least 1 request | |
2041 | * even if the batch times out, otherwise we could theoretically | |
2042 | * lose wakeups. | |
2043 | */ | |
2044 | return ioc->nr_batch_requests == q->nr_batching || | |
2045 | (ioc->nr_batch_requests > 0 | |
2046 | && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); | |
2047 | } | |
2048 | ||
2049 | /* | |
2050 | * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This | |
2051 | * will cause the process to be a "batcher" on all queues in the system. This | |
2052 | * is the behaviour we want though - once it gets a wakeup it should be given | |
2053 | * a nice run. | |
2054 | */ | |
93d17d3d | 2055 | static void ioc_set_batching(request_queue_t *q, struct io_context *ioc) |
1da177e4 LT |
2056 | { |
2057 | if (!ioc || ioc_batching(q, ioc)) | |
2058 | return; | |
2059 | ||
2060 | ioc->nr_batch_requests = q->nr_batching; | |
2061 | ioc->last_waited = jiffies; | |
2062 | } | |
2063 | ||
2064 | static void __freed_request(request_queue_t *q, int rw) | |
2065 | { | |
2066 | struct request_list *rl = &q->rq; | |
2067 | ||
2068 | if (rl->count[rw] < queue_congestion_off_threshold(q)) | |
2069 | clear_queue_congested(q, rw); | |
2070 | ||
2071 | if (rl->count[rw] + 1 <= q->nr_requests) { | |
1da177e4 LT |
2072 | if (waitqueue_active(&rl->wait[rw])) |
2073 | wake_up(&rl->wait[rw]); | |
2074 | ||
2075 | blk_clear_queue_full(q, rw); | |
2076 | } | |
2077 | } | |
2078 | ||
2079 | /* | |
2080 | * A request has just been released. Account for it, update the full and | |
2081 | * congestion status, wake up any waiters. Called under q->queue_lock. | |
2082 | */ | |
cb98fc8b | 2083 | static void freed_request(request_queue_t *q, int rw, int priv) |
1da177e4 LT |
2084 | { |
2085 | struct request_list *rl = &q->rq; | |
2086 | ||
2087 | rl->count[rw]--; | |
cb98fc8b TH |
2088 | if (priv) |
2089 | rl->elvpriv--; | |
1da177e4 LT |
2090 | |
2091 | __freed_request(q, rw); | |
2092 | ||
2093 | if (unlikely(rl->starved[rw ^ 1])) | |
2094 | __freed_request(q, rw ^ 1); | |
1da177e4 LT |
2095 | } |
2096 | ||
2097 | #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist) | |
2098 | /* | |
d6344532 NP |
2099 | * Get a free request, queue_lock must be held. |
2100 | * Returns NULL on failure, with queue_lock held. | |
2101 | * Returns !NULL on success, with queue_lock *not held*. | |
1da177e4 | 2102 | */ |
22e2c507 | 2103 | static struct request *get_request(request_queue_t *q, int rw, struct bio *bio, |
8267e268 | 2104 | gfp_t gfp_mask) |
1da177e4 LT |
2105 | { |
2106 | struct request *rq = NULL; | |
2107 | struct request_list *rl = &q->rq; | |
88ee5ef1 JA |
2108 | struct io_context *ioc = NULL; |
2109 | int may_queue, priv; | |
2110 | ||
cb78b285 | 2111 | may_queue = elv_may_queue(q, rw); |
88ee5ef1 JA |
2112 | if (may_queue == ELV_MQUEUE_NO) |
2113 | goto rq_starved; | |
2114 | ||
2115 | if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) { | |
2116 | if (rl->count[rw]+1 >= q->nr_requests) { | |
2117 | ioc = current_io_context(GFP_ATOMIC); | |
2118 | /* | |
2119 | * The queue will fill after this allocation, so set | |
2120 | * it as full, and mark this process as "batching". | |
2121 | * This process will be allowed to complete a batch of | |
2122 | * requests, others will be blocked. | |
2123 | */ | |
2124 | if (!blk_queue_full(q, rw)) { | |
2125 | ioc_set_batching(q, ioc); | |
2126 | blk_set_queue_full(q, rw); | |
2127 | } else { | |
2128 | if (may_queue != ELV_MQUEUE_MUST | |
2129 | && !ioc_batching(q, ioc)) { | |
2130 | /* | |
2131 | * The queue is full and the allocating | |
2132 | * process is not a "batcher", and not | |
2133 | * exempted by the IO scheduler | |
2134 | */ | |
2135 | goto out; | |
2136 | } | |
2137 | } | |
1da177e4 | 2138 | } |
88ee5ef1 | 2139 | set_queue_congested(q, rw); |
1da177e4 LT |
2140 | } |
2141 | ||
082cf69e JA |
2142 | /* |
2143 | * Only allow batching queuers to allocate up to 50% over the defined | |
2144 | * limit of requests, otherwise we could have thousands of requests | |
2145 | * allocated with any setting of ->nr_requests | |
2146 | */ | |
fd782a4a | 2147 | if (rl->count[rw] >= (3 * q->nr_requests / 2)) |
082cf69e | 2148 | goto out; |
fd782a4a | 2149 | |
1da177e4 LT |
2150 | rl->count[rw]++; |
2151 | rl->starved[rw] = 0; | |
cb98fc8b | 2152 | |
64521d1a | 2153 | priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
cb98fc8b TH |
2154 | if (priv) |
2155 | rl->elvpriv++; | |
2156 | ||
1da177e4 LT |
2157 | spin_unlock_irq(q->queue_lock); |
2158 | ||
cb78b285 | 2159 | rq = blk_alloc_request(q, rw, priv, gfp_mask); |
88ee5ef1 | 2160 | if (unlikely(!rq)) { |
1da177e4 LT |
2161 | /* |
2162 | * Allocation failed presumably due to memory. Undo anything | |
2163 | * we might have messed up. | |
2164 | * | |
2165 | * Allocating task should really be put onto the front of the | |
2166 | * wait queue, but this is pretty rare. | |
2167 | */ | |
2168 | spin_lock_irq(q->queue_lock); | |
cb98fc8b | 2169 | freed_request(q, rw, priv); |
1da177e4 LT |
2170 | |
2171 | /* | |
2172 | * in the very unlikely event that allocation failed and no | |
2173 | * requests for this direction was pending, mark us starved | |
2174 | * so that freeing of a request in the other direction will | |
2175 | * notice us. another possible fix would be to split the | |
2176 | * rq mempool into READ and WRITE | |
2177 | */ | |
2178 | rq_starved: | |
2179 | if (unlikely(rl->count[rw] == 0)) | |
2180 | rl->starved[rw] = 1; | |
2181 | ||
1da177e4 LT |
2182 | goto out; |
2183 | } | |
2184 | ||
88ee5ef1 JA |
2185 | /* |
2186 | * ioc may be NULL here, and ioc_batching will be false. That's | |
2187 | * OK, if the queue is under the request limit then requests need | |
2188 | * not count toward the nr_batch_requests limit. There will always | |
2189 | * be some limit enforced by BLK_BATCH_TIME. | |
2190 | */ | |
1da177e4 LT |
2191 | if (ioc_batching(q, ioc)) |
2192 | ioc->nr_batch_requests--; | |
2193 | ||
2194 | rq_init(q, rq); | |
2056a782 JA |
2195 | |
2196 | blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ); | |
1da177e4 | 2197 | out: |
1da177e4 LT |
2198 | return rq; |
2199 | } | |
2200 | ||
2201 | /* | |
2202 | * No available requests for this queue, unplug the device and wait for some | |
2203 | * requests to become available. | |
d6344532 NP |
2204 | * |
2205 | * Called with q->queue_lock held, and returns with it unlocked. | |
1da177e4 | 2206 | */ |
22e2c507 JA |
2207 | static struct request *get_request_wait(request_queue_t *q, int rw, |
2208 | struct bio *bio) | |
1da177e4 | 2209 | { |
1da177e4 LT |
2210 | struct request *rq; |
2211 | ||
450991bc NP |
2212 | rq = get_request(q, rw, bio, GFP_NOIO); |
2213 | while (!rq) { | |
2214 | DEFINE_WAIT(wait); | |
1da177e4 LT |
2215 | struct request_list *rl = &q->rq; |
2216 | ||
2217 | prepare_to_wait_exclusive(&rl->wait[rw], &wait, | |
2218 | TASK_UNINTERRUPTIBLE); | |
2219 | ||
22e2c507 | 2220 | rq = get_request(q, rw, bio, GFP_NOIO); |
1da177e4 LT |
2221 | |
2222 | if (!rq) { | |
2223 | struct io_context *ioc; | |
2224 | ||
2056a782 JA |
2225 | blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ); |
2226 | ||
d6344532 NP |
2227 | __generic_unplug_device(q); |
2228 | spin_unlock_irq(q->queue_lock); | |
1da177e4 LT |
2229 | io_schedule(); |
2230 | ||
2231 | /* | |
2232 | * After sleeping, we become a "batching" process and | |
2233 | * will be able to allocate at least one request, and | |
2234 | * up to a big batch of them for a small period time. | |
2235 | * See ioc_batching, ioc_set_batching | |
2236 | */ | |
fb3cc432 | 2237 | ioc = current_io_context(GFP_NOIO); |
1da177e4 | 2238 | ioc_set_batching(q, ioc); |
d6344532 NP |
2239 | |
2240 | spin_lock_irq(q->queue_lock); | |
1da177e4 LT |
2241 | } |
2242 | finish_wait(&rl->wait[rw], &wait); | |
450991bc | 2243 | } |
1da177e4 LT |
2244 | |
2245 | return rq; | |
2246 | } | |
2247 | ||
8267e268 | 2248 | struct request *blk_get_request(request_queue_t *q, int rw, gfp_t gfp_mask) |
1da177e4 LT |
2249 | { |
2250 | struct request *rq; | |
2251 | ||
2252 | BUG_ON(rw != READ && rw != WRITE); | |
2253 | ||
d6344532 NP |
2254 | spin_lock_irq(q->queue_lock); |
2255 | if (gfp_mask & __GFP_WAIT) { | |
22e2c507 | 2256 | rq = get_request_wait(q, rw, NULL); |
d6344532 | 2257 | } else { |
22e2c507 | 2258 | rq = get_request(q, rw, NULL, gfp_mask); |
d6344532 NP |
2259 | if (!rq) |
2260 | spin_unlock_irq(q->queue_lock); | |
2261 | } | |
2262 | /* q->queue_lock is unlocked at this point */ | |
1da177e4 LT |
2263 | |
2264 | return rq; | |
2265 | } | |
1da177e4 LT |
2266 | EXPORT_SYMBOL(blk_get_request); |
2267 | ||
2268 | /** | |
2269 | * blk_requeue_request - put a request back on queue | |
2270 | * @q: request queue where request should be inserted | |
2271 | * @rq: request to be inserted | |
2272 | * | |
2273 | * Description: | |
2274 | * Drivers often keep queueing requests until the hardware cannot accept | |
2275 | * more, when that condition happens we need to put the request back | |
2276 | * on the queue. Must be called with queue lock held. | |
2277 | */ | |
2278 | void blk_requeue_request(request_queue_t *q, struct request *rq) | |
2279 | { | |
2056a782 JA |
2280 | blk_add_trace_rq(q, rq, BLK_TA_REQUEUE); |
2281 | ||
1da177e4 LT |
2282 | if (blk_rq_tagged(rq)) |
2283 | blk_queue_end_tag(q, rq); | |
2284 | ||
2285 | elv_requeue_request(q, rq); | |
2286 | } | |
2287 | ||
2288 | EXPORT_SYMBOL(blk_requeue_request); | |
2289 | ||
2290 | /** | |
2291 | * blk_insert_request - insert a special request in to a request queue | |
2292 | * @q: request queue where request should be inserted | |
2293 | * @rq: request to be inserted | |
2294 | * @at_head: insert request at head or tail of queue | |
2295 | * @data: private data | |
1da177e4 LT |
2296 | * |
2297 | * Description: | |
2298 | * Many block devices need to execute commands asynchronously, so they don't | |
2299 | * block the whole kernel from preemption during request execution. This is | |
2300 | * accomplished normally by inserting aritficial requests tagged as | |
2301 | * REQ_SPECIAL in to the corresponding request queue, and letting them be | |
2302 | * scheduled for actual execution by the request queue. | |
2303 | * | |
2304 | * We have the option of inserting the head or the tail of the queue. | |
2305 | * Typically we use the tail for new ioctls and so forth. We use the head | |
2306 | * of the queue for things like a QUEUE_FULL message from a device, or a | |
2307 | * host that is unable to accept a particular command. | |
2308 | */ | |
2309 | void blk_insert_request(request_queue_t *q, struct request *rq, | |
867d1191 | 2310 | int at_head, void *data) |
1da177e4 | 2311 | { |
867d1191 | 2312 | int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; |
1da177e4 LT |
2313 | unsigned long flags; |
2314 | ||
2315 | /* | |
2316 | * tell I/O scheduler that this isn't a regular read/write (ie it | |
2317 | * must not attempt merges on this) and that it acts as a soft | |
2318 | * barrier | |
2319 | */ | |
4aff5e23 JA |
2320 | rq->cmd_type = REQ_TYPE_SPECIAL; |
2321 | rq->cmd_flags |= REQ_SOFTBARRIER; | |
1da177e4 LT |
2322 | |
2323 | rq->special = data; | |
2324 | ||
2325 | spin_lock_irqsave(q->queue_lock, flags); | |
2326 | ||
2327 | /* | |
2328 | * If command is tagged, release the tag | |
2329 | */ | |
867d1191 TH |
2330 | if (blk_rq_tagged(rq)) |
2331 | blk_queue_end_tag(q, rq); | |
1da177e4 | 2332 | |
867d1191 TH |
2333 | drive_stat_acct(rq, rq->nr_sectors, 1); |
2334 | __elv_add_request(q, rq, where, 0); | |
1da177e4 | 2335 | |
1da177e4 LT |
2336 | if (blk_queue_plugged(q)) |
2337 | __generic_unplug_device(q); | |
2338 | else | |
2339 | q->request_fn(q); | |
2340 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2341 | } | |
2342 | ||
2343 | EXPORT_SYMBOL(blk_insert_request); | |
2344 | ||
2345 | /** | |
2346 | * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage | |
2347 | * @q: request queue where request should be inserted | |
73747aed | 2348 | * @rq: request structure to fill |
1da177e4 LT |
2349 | * @ubuf: the user buffer |
2350 | * @len: length of user data | |
2351 | * | |
2352 | * Description: | |
2353 | * Data will be mapped directly for zero copy io, if possible. Otherwise | |
2354 | * a kernel bounce buffer is used. | |
2355 | * | |
2356 | * A matching blk_rq_unmap_user() must be issued at the end of io, while | |
2357 | * still in process context. | |
2358 | * | |
2359 | * Note: The mapped bio may need to be bounced through blk_queue_bounce() | |
2360 | * before being submitted to the device, as pages mapped may be out of | |
2361 | * reach. It's the callers responsibility to make sure this happens. The | |
2362 | * original bio must be passed back in to blk_rq_unmap_user() for proper | |
2363 | * unmapping. | |
2364 | */ | |
dd1cab95 JA |
2365 | int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf, |
2366 | unsigned int len) | |
1da177e4 LT |
2367 | { |
2368 | unsigned long uaddr; | |
1da177e4 | 2369 | struct bio *bio; |
dd1cab95 | 2370 | int reading; |
1da177e4 | 2371 | |
defd94b7 | 2372 | if (len > (q->max_hw_sectors << 9)) |
dd1cab95 JA |
2373 | return -EINVAL; |
2374 | if (!len || !ubuf) | |
2375 | return -EINVAL; | |
1da177e4 | 2376 | |
dd1cab95 | 2377 | reading = rq_data_dir(rq) == READ; |
1da177e4 LT |
2378 | |
2379 | /* | |
2380 | * if alignment requirement is satisfied, map in user pages for | |
2381 | * direct dma. else, set up kernel bounce buffers | |
2382 | */ | |
2383 | uaddr = (unsigned long) ubuf; | |
2384 | if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q))) | |
dd1cab95 | 2385 | bio = bio_map_user(q, NULL, uaddr, len, reading); |
1da177e4 | 2386 | else |
dd1cab95 | 2387 | bio = bio_copy_user(q, uaddr, len, reading); |
1da177e4 LT |
2388 | |
2389 | if (!IS_ERR(bio)) { | |
2390 | rq->bio = rq->biotail = bio; | |
2391 | blk_rq_bio_prep(q, rq, bio); | |
2392 | ||
2393 | rq->buffer = rq->data = NULL; | |
2394 | rq->data_len = len; | |
dd1cab95 | 2395 | return 0; |
1da177e4 LT |
2396 | } |
2397 | ||
2398 | /* | |
2399 | * bio is the err-ptr | |
2400 | */ | |
dd1cab95 | 2401 | return PTR_ERR(bio); |
1da177e4 LT |
2402 | } |
2403 | ||
2404 | EXPORT_SYMBOL(blk_rq_map_user); | |
2405 | ||
f1970baf JB |
2406 | /** |
2407 | * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage | |
2408 | * @q: request queue where request should be inserted | |
2409 | * @rq: request to map data to | |
2410 | * @iov: pointer to the iovec | |
2411 | * @iov_count: number of elements in the iovec | |
2412 | * | |
2413 | * Description: | |
2414 | * Data will be mapped directly for zero copy io, if possible. Otherwise | |
2415 | * a kernel bounce buffer is used. | |
2416 | * | |
2417 | * A matching blk_rq_unmap_user() must be issued at the end of io, while | |
2418 | * still in process context. | |
2419 | * | |
2420 | * Note: The mapped bio may need to be bounced through blk_queue_bounce() | |
2421 | * before being submitted to the device, as pages mapped may be out of | |
2422 | * reach. It's the callers responsibility to make sure this happens. The | |
2423 | * original bio must be passed back in to blk_rq_unmap_user() for proper | |
2424 | * unmapping. | |
2425 | */ | |
2426 | int blk_rq_map_user_iov(request_queue_t *q, struct request *rq, | |
2427 | struct sg_iovec *iov, int iov_count) | |
2428 | { | |
2429 | struct bio *bio; | |
2430 | ||
2431 | if (!iov || iov_count <= 0) | |
2432 | return -EINVAL; | |
2433 | ||
2434 | /* we don't allow misaligned data like bio_map_user() does. If the | |
2435 | * user is using sg, they're expected to know the alignment constraints | |
2436 | * and respect them accordingly */ | |
2437 | bio = bio_map_user_iov(q, NULL, iov, iov_count, rq_data_dir(rq)== READ); | |
2438 | if (IS_ERR(bio)) | |
2439 | return PTR_ERR(bio); | |
2440 | ||
2441 | rq->bio = rq->biotail = bio; | |
2442 | blk_rq_bio_prep(q, rq, bio); | |
2443 | rq->buffer = rq->data = NULL; | |
2444 | rq->data_len = bio->bi_size; | |
2445 | return 0; | |
2446 | } | |
2447 | ||
2448 | EXPORT_SYMBOL(blk_rq_map_user_iov); | |
2449 | ||
1da177e4 LT |
2450 | /** |
2451 | * blk_rq_unmap_user - unmap a request with user data | |
73747aed | 2452 | * @bio: bio to be unmapped |
1da177e4 LT |
2453 | * @ulen: length of user buffer |
2454 | * | |
2455 | * Description: | |
73747aed | 2456 | * Unmap a bio previously mapped by blk_rq_map_user(). |
1da177e4 | 2457 | */ |
dd1cab95 | 2458 | int blk_rq_unmap_user(struct bio *bio, unsigned int ulen) |
1da177e4 LT |
2459 | { |
2460 | int ret = 0; | |
2461 | ||
2462 | if (bio) { | |
2463 | if (bio_flagged(bio, BIO_USER_MAPPED)) | |
2464 | bio_unmap_user(bio); | |
2465 | else | |
2466 | ret = bio_uncopy_user(bio); | |
2467 | } | |
2468 | ||
dd1cab95 | 2469 | return 0; |
1da177e4 LT |
2470 | } |
2471 | ||
2472 | EXPORT_SYMBOL(blk_rq_unmap_user); | |
2473 | ||
df46b9a4 MC |
2474 | /** |
2475 | * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage | |
2476 | * @q: request queue where request should be inserted | |
73747aed | 2477 | * @rq: request to fill |
df46b9a4 MC |
2478 | * @kbuf: the kernel buffer |
2479 | * @len: length of user data | |
73747aed | 2480 | * @gfp_mask: memory allocation flags |
df46b9a4 | 2481 | */ |
dd1cab95 | 2482 | int blk_rq_map_kern(request_queue_t *q, struct request *rq, void *kbuf, |
8267e268 | 2483 | unsigned int len, gfp_t gfp_mask) |
df46b9a4 | 2484 | { |
df46b9a4 MC |
2485 | struct bio *bio; |
2486 | ||
defd94b7 | 2487 | if (len > (q->max_hw_sectors << 9)) |
dd1cab95 JA |
2488 | return -EINVAL; |
2489 | if (!len || !kbuf) | |
2490 | return -EINVAL; | |
df46b9a4 MC |
2491 | |
2492 | bio = bio_map_kern(q, kbuf, len, gfp_mask); | |
dd1cab95 JA |
2493 | if (IS_ERR(bio)) |
2494 | return PTR_ERR(bio); | |
df46b9a4 | 2495 | |
dd1cab95 JA |
2496 | if (rq_data_dir(rq) == WRITE) |
2497 | bio->bi_rw |= (1 << BIO_RW); | |
df46b9a4 | 2498 | |
dd1cab95 JA |
2499 | rq->bio = rq->biotail = bio; |
2500 | blk_rq_bio_prep(q, rq, bio); | |
df46b9a4 | 2501 | |
dd1cab95 JA |
2502 | rq->buffer = rq->data = NULL; |
2503 | rq->data_len = len; | |
2504 | return 0; | |
df46b9a4 MC |
2505 | } |
2506 | ||
2507 | EXPORT_SYMBOL(blk_rq_map_kern); | |
2508 | ||
73747aed CH |
2509 | /** |
2510 | * blk_execute_rq_nowait - insert a request into queue for execution | |
2511 | * @q: queue to insert the request in | |
2512 | * @bd_disk: matching gendisk | |
2513 | * @rq: request to insert | |
2514 | * @at_head: insert request at head or tail of queue | |
2515 | * @done: I/O completion handler | |
2516 | * | |
2517 | * Description: | |
2518 | * Insert a fully prepared request at the back of the io scheduler queue | |
2519 | * for execution. Don't wait for completion. | |
2520 | */ | |
f1970baf JB |
2521 | void blk_execute_rq_nowait(request_queue_t *q, struct gendisk *bd_disk, |
2522 | struct request *rq, int at_head, | |
8ffdc655 | 2523 | rq_end_io_fn *done) |
f1970baf JB |
2524 | { |
2525 | int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; | |
2526 | ||
2527 | rq->rq_disk = bd_disk; | |
4aff5e23 | 2528 | rq->cmd_flags |= REQ_NOMERGE; |
f1970baf | 2529 | rq->end_io = done; |
4c5d0bbd AM |
2530 | WARN_ON(irqs_disabled()); |
2531 | spin_lock_irq(q->queue_lock); | |
2532 | __elv_add_request(q, rq, where, 1); | |
2533 | __generic_unplug_device(q); | |
2534 | spin_unlock_irq(q->queue_lock); | |
f1970baf | 2535 | } |
6e39b69e MC |
2536 | EXPORT_SYMBOL_GPL(blk_execute_rq_nowait); |
2537 | ||
1da177e4 LT |
2538 | /** |
2539 | * blk_execute_rq - insert a request into queue for execution | |
2540 | * @q: queue to insert the request in | |
2541 | * @bd_disk: matching gendisk | |
2542 | * @rq: request to insert | |
994ca9a1 | 2543 | * @at_head: insert request at head or tail of queue |
1da177e4 LT |
2544 | * |
2545 | * Description: | |
2546 | * Insert a fully prepared request at the back of the io scheduler queue | |
73747aed | 2547 | * for execution and wait for completion. |
1da177e4 LT |
2548 | */ |
2549 | int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk, | |
994ca9a1 | 2550 | struct request *rq, int at_head) |
1da177e4 | 2551 | { |
60be6b9a | 2552 | DECLARE_COMPLETION_ONSTACK(wait); |
1da177e4 LT |
2553 | char sense[SCSI_SENSE_BUFFERSIZE]; |
2554 | int err = 0; | |
2555 | ||
1da177e4 LT |
2556 | /* |
2557 | * we need an extra reference to the request, so we can look at | |
2558 | * it after io completion | |
2559 | */ | |
2560 | rq->ref_count++; | |
2561 | ||
2562 | if (!rq->sense) { | |
2563 | memset(sense, 0, sizeof(sense)); | |
2564 | rq->sense = sense; | |
2565 | rq->sense_len = 0; | |
2566 | } | |
2567 | ||
c00895ab | 2568 | rq->end_io_data = &wait; |
994ca9a1 | 2569 | blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq); |
1da177e4 | 2570 | wait_for_completion(&wait); |
1da177e4 LT |
2571 | |
2572 | if (rq->errors) | |
2573 | err = -EIO; | |
2574 | ||
2575 | return err; | |
2576 | } | |
2577 | ||
2578 | EXPORT_SYMBOL(blk_execute_rq); | |
2579 | ||
2580 | /** | |
2581 | * blkdev_issue_flush - queue a flush | |
2582 | * @bdev: blockdev to issue flush for | |
2583 | * @error_sector: error sector | |
2584 | * | |
2585 | * Description: | |
2586 | * Issue a flush for the block device in question. Caller can supply | |
2587 | * room for storing the error offset in case of a flush error, if they | |
2588 | * wish to. Caller must run wait_for_completion() on its own. | |
2589 | */ | |
2590 | int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector) | |
2591 | { | |
2592 | request_queue_t *q; | |
2593 | ||
2594 | if (bdev->bd_disk == NULL) | |
2595 | return -ENXIO; | |
2596 | ||
2597 | q = bdev_get_queue(bdev); | |
2598 | if (!q) | |
2599 | return -ENXIO; | |
2600 | if (!q->issue_flush_fn) | |
2601 | return -EOPNOTSUPP; | |
2602 | ||
2603 | return q->issue_flush_fn(q, bdev->bd_disk, error_sector); | |
2604 | } | |
2605 | ||
2606 | EXPORT_SYMBOL(blkdev_issue_flush); | |
2607 | ||
93d17d3d | 2608 | static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io) |
1da177e4 LT |
2609 | { |
2610 | int rw = rq_data_dir(rq); | |
2611 | ||
2612 | if (!blk_fs_request(rq) || !rq->rq_disk) | |
2613 | return; | |
2614 | ||
d72d904a | 2615 | if (!new_io) { |
a362357b | 2616 | __disk_stat_inc(rq->rq_disk, merges[rw]); |
d72d904a | 2617 | } else { |
1da177e4 LT |
2618 | disk_round_stats(rq->rq_disk); |
2619 | rq->rq_disk->in_flight++; | |
2620 | } | |
2621 | } | |
2622 | ||
2623 | /* | |
2624 | * add-request adds a request to the linked list. | |
2625 | * queue lock is held and interrupts disabled, as we muck with the | |
2626 | * request queue list. | |
2627 | */ | |
2628 | static inline void add_request(request_queue_t * q, struct request * req) | |
2629 | { | |
2630 | drive_stat_acct(req, req->nr_sectors, 1); | |
2631 | ||
2632 | if (q->activity_fn) | |
2633 | q->activity_fn(q->activity_data, rq_data_dir(req)); | |
2634 | ||
2635 | /* | |
2636 | * elevator indicated where it wants this request to be | |
2637 | * inserted at elevator_merge time | |
2638 | */ | |
2639 | __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0); | |
2640 | } | |
2641 | ||
2642 | /* | |
2643 | * disk_round_stats() - Round off the performance stats on a struct | |
2644 | * disk_stats. | |
2645 | * | |
2646 | * The average IO queue length and utilisation statistics are maintained | |
2647 | * by observing the current state of the queue length and the amount of | |
2648 | * time it has been in this state for. | |
2649 | * | |
2650 | * Normally, that accounting is done on IO completion, but that can result | |
2651 | * in more than a second's worth of IO being accounted for within any one | |
2652 | * second, leading to >100% utilisation. To deal with that, we call this | |
2653 | * function to do a round-off before returning the results when reading | |
2654 | * /proc/diskstats. This accounts immediately for all queue usage up to | |
2655 | * the current jiffies and restarts the counters again. | |
2656 | */ | |
2657 | void disk_round_stats(struct gendisk *disk) | |
2658 | { | |
2659 | unsigned long now = jiffies; | |
2660 | ||
b2982649 KC |
2661 | if (now == disk->stamp) |
2662 | return; | |
1da177e4 | 2663 | |
20e5c81f KC |
2664 | if (disk->in_flight) { |
2665 | __disk_stat_add(disk, time_in_queue, | |
2666 | disk->in_flight * (now - disk->stamp)); | |
2667 | __disk_stat_add(disk, io_ticks, (now - disk->stamp)); | |
2668 | } | |
1da177e4 | 2669 | disk->stamp = now; |
1da177e4 LT |
2670 | } |
2671 | ||
3eaf840e JNN |
2672 | EXPORT_SYMBOL_GPL(disk_round_stats); |
2673 | ||
1da177e4 LT |
2674 | /* |
2675 | * queue lock must be held | |
2676 | */ | |
6e39b69e | 2677 | void __blk_put_request(request_queue_t *q, struct request *req) |
1da177e4 | 2678 | { |
1da177e4 LT |
2679 | if (unlikely(!q)) |
2680 | return; | |
2681 | if (unlikely(--req->ref_count)) | |
2682 | return; | |
2683 | ||
8922e16c TH |
2684 | elv_completed_request(q, req); |
2685 | ||
1da177e4 LT |
2686 | /* |
2687 | * Request may not have originated from ll_rw_blk. if not, | |
2688 | * it didn't come out of our reserved rq pools | |
2689 | */ | |
49171e5c | 2690 | if (req->cmd_flags & REQ_ALLOCED) { |
1da177e4 | 2691 | int rw = rq_data_dir(req); |
4aff5e23 | 2692 | int priv = req->cmd_flags & REQ_ELVPRIV; |
1da177e4 | 2693 | |
1da177e4 | 2694 | BUG_ON(!list_empty(&req->queuelist)); |
9817064b | 2695 | BUG_ON(!hlist_unhashed(&req->hash)); |
1da177e4 LT |
2696 | |
2697 | blk_free_request(q, req); | |
cb98fc8b | 2698 | freed_request(q, rw, priv); |
1da177e4 LT |
2699 | } |
2700 | } | |
2701 | ||
6e39b69e MC |
2702 | EXPORT_SYMBOL_GPL(__blk_put_request); |
2703 | ||
1da177e4 LT |
2704 | void blk_put_request(struct request *req) |
2705 | { | |
8922e16c TH |
2706 | unsigned long flags; |
2707 | request_queue_t *q = req->q; | |
2708 | ||
1da177e4 | 2709 | /* |
8922e16c TH |
2710 | * Gee, IDE calls in w/ NULL q. Fix IDE and remove the |
2711 | * following if (q) test. | |
1da177e4 | 2712 | */ |
8922e16c | 2713 | if (q) { |
1da177e4 LT |
2714 | spin_lock_irqsave(q->queue_lock, flags); |
2715 | __blk_put_request(q, req); | |
2716 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2717 | } | |
2718 | } | |
2719 | ||
2720 | EXPORT_SYMBOL(blk_put_request); | |
2721 | ||
2722 | /** | |
2723 | * blk_end_sync_rq - executes a completion event on a request | |
2724 | * @rq: request to complete | |
fddfdeaf | 2725 | * @error: end io status of the request |
1da177e4 | 2726 | */ |
8ffdc655 | 2727 | void blk_end_sync_rq(struct request *rq, int error) |
1da177e4 | 2728 | { |
c00895ab | 2729 | struct completion *waiting = rq->end_io_data; |
1da177e4 | 2730 | |
c00895ab | 2731 | rq->end_io_data = NULL; |
1da177e4 LT |
2732 | __blk_put_request(rq->q, rq); |
2733 | ||
2734 | /* | |
2735 | * complete last, if this is a stack request the process (and thus | |
2736 | * the rq pointer) could be invalid right after this complete() | |
2737 | */ | |
2738 | complete(waiting); | |
2739 | } | |
2740 | EXPORT_SYMBOL(blk_end_sync_rq); | |
2741 | ||
2742 | /** | |
2743 | * blk_congestion_wait - wait for a queue to become uncongested | |
2744 | * @rw: READ or WRITE | |
2745 | * @timeout: timeout in jiffies | |
2746 | * | |
2747 | * Waits for up to @timeout jiffies for a queue (any queue) to exit congestion. | |
2748 | * If no queues are congested then just wait for the next request to be | |
2749 | * returned. | |
2750 | */ | |
2751 | long blk_congestion_wait(int rw, long timeout) | |
2752 | { | |
2753 | long ret; | |
2754 | DEFINE_WAIT(wait); | |
2755 | wait_queue_head_t *wqh = &congestion_wqh[rw]; | |
2756 | ||
2757 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
2758 | ret = io_schedule_timeout(timeout); | |
2759 | finish_wait(wqh, &wait); | |
2760 | return ret; | |
2761 | } | |
2762 | ||
2763 | EXPORT_SYMBOL(blk_congestion_wait); | |
2764 | ||
275a082f TM |
2765 | /** |
2766 | * blk_congestion_end - wake up sleepers on a congestion queue | |
2767 | * @rw: READ or WRITE | |
2768 | */ | |
2769 | void blk_congestion_end(int rw) | |
2770 | { | |
2771 | wait_queue_head_t *wqh = &congestion_wqh[rw]; | |
2772 | ||
2773 | if (waitqueue_active(wqh)) | |
2774 | wake_up(wqh); | |
2775 | } | |
2776 | ||
1da177e4 LT |
2777 | /* |
2778 | * Has to be called with the request spinlock acquired | |
2779 | */ | |
2780 | static int attempt_merge(request_queue_t *q, struct request *req, | |
2781 | struct request *next) | |
2782 | { | |
2783 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
2784 | return 0; | |
2785 | ||
2786 | /* | |
d6e05edc | 2787 | * not contiguous |
1da177e4 LT |
2788 | */ |
2789 | if (req->sector + req->nr_sectors != next->sector) | |
2790 | return 0; | |
2791 | ||
2792 | if (rq_data_dir(req) != rq_data_dir(next) | |
2793 | || req->rq_disk != next->rq_disk | |
c00895ab | 2794 | || next->special) |
1da177e4 LT |
2795 | return 0; |
2796 | ||
2797 | /* | |
2798 | * If we are allowed to merge, then append bio list | |
2799 | * from next to rq and release next. merge_requests_fn | |
2800 | * will have updated segment counts, update sector | |
2801 | * counts here. | |
2802 | */ | |
2803 | if (!q->merge_requests_fn(q, req, next)) | |
2804 | return 0; | |
2805 | ||
2806 | /* | |
2807 | * At this point we have either done a back merge | |
2808 | * or front merge. We need the smaller start_time of | |
2809 | * the merged requests to be the current request | |
2810 | * for accounting purposes. | |
2811 | */ | |
2812 | if (time_after(req->start_time, next->start_time)) | |
2813 | req->start_time = next->start_time; | |
2814 | ||
2815 | req->biotail->bi_next = next->bio; | |
2816 | req->biotail = next->biotail; | |
2817 | ||
2818 | req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors; | |
2819 | ||
2820 | elv_merge_requests(q, req, next); | |
2821 | ||
2822 | if (req->rq_disk) { | |
2823 | disk_round_stats(req->rq_disk); | |
2824 | req->rq_disk->in_flight--; | |
2825 | } | |
2826 | ||
22e2c507 JA |
2827 | req->ioprio = ioprio_best(req->ioprio, next->ioprio); |
2828 | ||
1da177e4 LT |
2829 | __blk_put_request(q, next); |
2830 | return 1; | |
2831 | } | |
2832 | ||
2833 | static inline int attempt_back_merge(request_queue_t *q, struct request *rq) | |
2834 | { | |
2835 | struct request *next = elv_latter_request(q, rq); | |
2836 | ||
2837 | if (next) | |
2838 | return attempt_merge(q, rq, next); | |
2839 | ||
2840 | return 0; | |
2841 | } | |
2842 | ||
2843 | static inline int attempt_front_merge(request_queue_t *q, struct request *rq) | |
2844 | { | |
2845 | struct request *prev = elv_former_request(q, rq); | |
2846 | ||
2847 | if (prev) | |
2848 | return attempt_merge(q, prev, rq); | |
2849 | ||
2850 | return 0; | |
2851 | } | |
2852 | ||
52d9e675 TH |
2853 | static void init_request_from_bio(struct request *req, struct bio *bio) |
2854 | { | |
4aff5e23 | 2855 | req->cmd_type = REQ_TYPE_FS; |
52d9e675 TH |
2856 | |
2857 | /* | |
2858 | * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST) | |
2859 | */ | |
2860 | if (bio_rw_ahead(bio) || bio_failfast(bio)) | |
4aff5e23 | 2861 | req->cmd_flags |= REQ_FAILFAST; |
52d9e675 TH |
2862 | |
2863 | /* | |
2864 | * REQ_BARRIER implies no merging, but lets make it explicit | |
2865 | */ | |
2866 | if (unlikely(bio_barrier(bio))) | |
4aff5e23 | 2867 | req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE); |
52d9e675 | 2868 | |
b31dc66a | 2869 | if (bio_sync(bio)) |
4aff5e23 | 2870 | req->cmd_flags |= REQ_RW_SYNC; |
b31dc66a | 2871 | |
52d9e675 TH |
2872 | req->errors = 0; |
2873 | req->hard_sector = req->sector = bio->bi_sector; | |
2874 | req->hard_nr_sectors = req->nr_sectors = bio_sectors(bio); | |
2875 | req->current_nr_sectors = req->hard_cur_sectors = bio_cur_sectors(bio); | |
2876 | req->nr_phys_segments = bio_phys_segments(req->q, bio); | |
2877 | req->nr_hw_segments = bio_hw_segments(req->q, bio); | |
2878 | req->buffer = bio_data(bio); /* see ->buffer comment above */ | |
52d9e675 TH |
2879 | req->bio = req->biotail = bio; |
2880 | req->ioprio = bio_prio(bio); | |
2881 | req->rq_disk = bio->bi_bdev->bd_disk; | |
2882 | req->start_time = jiffies; | |
2883 | } | |
2884 | ||
1da177e4 LT |
2885 | static int __make_request(request_queue_t *q, struct bio *bio) |
2886 | { | |
450991bc | 2887 | struct request *req; |
51da90fc JA |
2888 | int el_ret, nr_sectors, barrier, err; |
2889 | const unsigned short prio = bio_prio(bio); | |
2890 | const int sync = bio_sync(bio); | |
1da177e4 | 2891 | |
1da177e4 | 2892 | nr_sectors = bio_sectors(bio); |
1da177e4 LT |
2893 | |
2894 | /* | |
2895 | * low level driver can indicate that it wants pages above a | |
2896 | * certain limit bounced to low memory (ie for highmem, or even | |
2897 | * ISA dma in theory) | |
2898 | */ | |
2899 | blk_queue_bounce(q, &bio); | |
2900 | ||
1da177e4 | 2901 | barrier = bio_barrier(bio); |
797e7dbb | 2902 | if (unlikely(barrier) && (q->next_ordered == QUEUE_ORDERED_NONE)) { |
1da177e4 LT |
2903 | err = -EOPNOTSUPP; |
2904 | goto end_io; | |
2905 | } | |
2906 | ||
1da177e4 LT |
2907 | spin_lock_irq(q->queue_lock); |
2908 | ||
450991bc | 2909 | if (unlikely(barrier) || elv_queue_empty(q)) |
1da177e4 LT |
2910 | goto get_rq; |
2911 | ||
2912 | el_ret = elv_merge(q, &req, bio); | |
2913 | switch (el_ret) { | |
2914 | case ELEVATOR_BACK_MERGE: | |
2915 | BUG_ON(!rq_mergeable(req)); | |
2916 | ||
2917 | if (!q->back_merge_fn(q, req, bio)) | |
2918 | break; | |
2919 | ||
2056a782 JA |
2920 | blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE); |
2921 | ||
1da177e4 LT |
2922 | req->biotail->bi_next = bio; |
2923 | req->biotail = bio; | |
2924 | req->nr_sectors = req->hard_nr_sectors += nr_sectors; | |
22e2c507 | 2925 | req->ioprio = ioprio_best(req->ioprio, prio); |
1da177e4 LT |
2926 | drive_stat_acct(req, nr_sectors, 0); |
2927 | if (!attempt_back_merge(q, req)) | |
2e662b65 | 2928 | elv_merged_request(q, req, el_ret); |
1da177e4 LT |
2929 | goto out; |
2930 | ||
2931 | case ELEVATOR_FRONT_MERGE: | |
2932 | BUG_ON(!rq_mergeable(req)); | |
2933 | ||
2934 | if (!q->front_merge_fn(q, req, bio)) | |
2935 | break; | |
2936 | ||
2056a782 JA |
2937 | blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE); |
2938 | ||
1da177e4 LT |
2939 | bio->bi_next = req->bio; |
2940 | req->bio = bio; | |
2941 | ||
2942 | /* | |
2943 | * may not be valid. if the low level driver said | |
2944 | * it didn't need a bounce buffer then it better | |
2945 | * not touch req->buffer either... | |
2946 | */ | |
2947 | req->buffer = bio_data(bio); | |
51da90fc JA |
2948 | req->current_nr_sectors = bio_cur_sectors(bio); |
2949 | req->hard_cur_sectors = req->current_nr_sectors; | |
2950 | req->sector = req->hard_sector = bio->bi_sector; | |
1da177e4 | 2951 | req->nr_sectors = req->hard_nr_sectors += nr_sectors; |
22e2c507 | 2952 | req->ioprio = ioprio_best(req->ioprio, prio); |
1da177e4 LT |
2953 | drive_stat_acct(req, nr_sectors, 0); |
2954 | if (!attempt_front_merge(q, req)) | |
2e662b65 | 2955 | elv_merged_request(q, req, el_ret); |
1da177e4 LT |
2956 | goto out; |
2957 | ||
450991bc | 2958 | /* ELV_NO_MERGE: elevator says don't/can't merge. */ |
1da177e4 | 2959 | default: |
450991bc | 2960 | ; |
1da177e4 LT |
2961 | } |
2962 | ||
450991bc | 2963 | get_rq: |
1da177e4 | 2964 | /* |
450991bc | 2965 | * Grab a free request. This is might sleep but can not fail. |
d6344532 | 2966 | * Returns with the queue unlocked. |
450991bc | 2967 | */ |
51da90fc | 2968 | req = get_request_wait(q, bio_data_dir(bio), bio); |
d6344532 | 2969 | |
450991bc NP |
2970 | /* |
2971 | * After dropping the lock and possibly sleeping here, our request | |
2972 | * may now be mergeable after it had proven unmergeable (above). | |
2973 | * We don't worry about that case for efficiency. It won't happen | |
2974 | * often, and the elevators are able to handle it. | |
1da177e4 | 2975 | */ |
52d9e675 | 2976 | init_request_from_bio(req, bio); |
1da177e4 | 2977 | |
450991bc NP |
2978 | spin_lock_irq(q->queue_lock); |
2979 | if (elv_queue_empty(q)) | |
2980 | blk_plug_device(q); | |
1da177e4 LT |
2981 | add_request(q, req); |
2982 | out: | |
4a534f93 | 2983 | if (sync) |
1da177e4 LT |
2984 | __generic_unplug_device(q); |
2985 | ||
2986 | spin_unlock_irq(q->queue_lock); | |
2987 | return 0; | |
2988 | ||
2989 | end_io: | |
2990 | bio_endio(bio, nr_sectors << 9, err); | |
2991 | return 0; | |
2992 | } | |
2993 | ||
2994 | /* | |
2995 | * If bio->bi_dev is a partition, remap the location | |
2996 | */ | |
2997 | static inline void blk_partition_remap(struct bio *bio) | |
2998 | { | |
2999 | struct block_device *bdev = bio->bi_bdev; | |
3000 | ||
3001 | if (bdev != bdev->bd_contains) { | |
3002 | struct hd_struct *p = bdev->bd_part; | |
a362357b JA |
3003 | const int rw = bio_data_dir(bio); |
3004 | ||
3005 | p->sectors[rw] += bio_sectors(bio); | |
3006 | p->ios[rw]++; | |
1da177e4 | 3007 | |
1da177e4 LT |
3008 | bio->bi_sector += p->start_sect; |
3009 | bio->bi_bdev = bdev->bd_contains; | |
3010 | } | |
3011 | } | |
3012 | ||
1da177e4 LT |
3013 | static void handle_bad_sector(struct bio *bio) |
3014 | { | |
3015 | char b[BDEVNAME_SIZE]; | |
3016 | ||
3017 | printk(KERN_INFO "attempt to access beyond end of device\n"); | |
3018 | printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", | |
3019 | bdevname(bio->bi_bdev, b), | |
3020 | bio->bi_rw, | |
3021 | (unsigned long long)bio->bi_sector + bio_sectors(bio), | |
3022 | (long long)(bio->bi_bdev->bd_inode->i_size >> 9)); | |
3023 | ||
3024 | set_bit(BIO_EOF, &bio->bi_flags); | |
3025 | } | |
3026 | ||
3027 | /** | |
3028 | * generic_make_request: hand a buffer to its device driver for I/O | |
3029 | * @bio: The bio describing the location in memory and on the device. | |
3030 | * | |
3031 | * generic_make_request() is used to make I/O requests of block | |
3032 | * devices. It is passed a &struct bio, which describes the I/O that needs | |
3033 | * to be done. | |
3034 | * | |
3035 | * generic_make_request() does not return any status. The | |
3036 | * success/failure status of the request, along with notification of | |
3037 | * completion, is delivered asynchronously through the bio->bi_end_io | |
3038 | * function described (one day) else where. | |
3039 | * | |
3040 | * The caller of generic_make_request must make sure that bi_io_vec | |
3041 | * are set to describe the memory buffer, and that bi_dev and bi_sector are | |
3042 | * set to describe the device address, and the | |
3043 | * bi_end_io and optionally bi_private are set to describe how | |
3044 | * completion notification should be signaled. | |
3045 | * | |
3046 | * generic_make_request and the drivers it calls may use bi_next if this | |
3047 | * bio happens to be merged with someone else, and may change bi_dev and | |
3048 | * bi_sector for remaps as it sees fit. So the values of these fields | |
3049 | * should NOT be depended on after the call to generic_make_request. | |
3050 | */ | |
3051 | void generic_make_request(struct bio *bio) | |
3052 | { | |
3053 | request_queue_t *q; | |
3054 | sector_t maxsector; | |
3055 | int ret, nr_sectors = bio_sectors(bio); | |
2056a782 | 3056 | dev_t old_dev; |
1da177e4 LT |
3057 | |
3058 | might_sleep(); | |
3059 | /* Test device or partition size, when known. */ | |
3060 | maxsector = bio->bi_bdev->bd_inode->i_size >> 9; | |
3061 | if (maxsector) { | |
3062 | sector_t sector = bio->bi_sector; | |
3063 | ||
3064 | if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { | |
3065 | /* | |
3066 | * This may well happen - the kernel calls bread() | |
3067 | * without checking the size of the device, e.g., when | |
3068 | * mounting a device. | |
3069 | */ | |
3070 | handle_bad_sector(bio); | |
3071 | goto end_io; | |
3072 | } | |
3073 | } | |
3074 | ||
3075 | /* | |
3076 | * Resolve the mapping until finished. (drivers are | |
3077 | * still free to implement/resolve their own stacking | |
3078 | * by explicitly returning 0) | |
3079 | * | |
3080 | * NOTE: we don't repeat the blk_size check for each new device. | |
3081 | * Stacking drivers are expected to know what they are doing. | |
3082 | */ | |
2056a782 JA |
3083 | maxsector = -1; |
3084 | old_dev = 0; | |
1da177e4 LT |
3085 | do { |
3086 | char b[BDEVNAME_SIZE]; | |
3087 | ||
3088 | q = bdev_get_queue(bio->bi_bdev); | |
3089 | if (!q) { | |
3090 | printk(KERN_ERR | |
3091 | "generic_make_request: Trying to access " | |
3092 | "nonexistent block-device %s (%Lu)\n", | |
3093 | bdevname(bio->bi_bdev, b), | |
3094 | (long long) bio->bi_sector); | |
3095 | end_io: | |
3096 | bio_endio(bio, bio->bi_size, -EIO); | |
3097 | break; | |
3098 | } | |
3099 | ||
3100 | if (unlikely(bio_sectors(bio) > q->max_hw_sectors)) { | |
3101 | printk("bio too big device %s (%u > %u)\n", | |
3102 | bdevname(bio->bi_bdev, b), | |
3103 | bio_sectors(bio), | |
3104 | q->max_hw_sectors); | |
3105 | goto end_io; | |
3106 | } | |
3107 | ||
fde6ad22 | 3108 | if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) |
1da177e4 LT |
3109 | goto end_io; |
3110 | ||
1da177e4 LT |
3111 | /* |
3112 | * If this device has partitions, remap block n | |
3113 | * of partition p to block n+start(p) of the disk. | |
3114 | */ | |
3115 | blk_partition_remap(bio); | |
3116 | ||
2056a782 JA |
3117 | if (maxsector != -1) |
3118 | blk_add_trace_remap(q, bio, old_dev, bio->bi_sector, | |
3119 | maxsector); | |
3120 | ||
3121 | blk_add_trace_bio(q, bio, BLK_TA_QUEUE); | |
3122 | ||
3123 | maxsector = bio->bi_sector; | |
3124 | old_dev = bio->bi_bdev->bd_dev; | |
3125 | ||
1da177e4 LT |
3126 | ret = q->make_request_fn(q, bio); |
3127 | } while (ret); | |
3128 | } | |
3129 | ||
3130 | EXPORT_SYMBOL(generic_make_request); | |
3131 | ||
3132 | /** | |
3133 | * submit_bio: submit a bio to the block device layer for I/O | |
3134 | * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) | |
3135 | * @bio: The &struct bio which describes the I/O | |
3136 | * | |
3137 | * submit_bio() is very similar in purpose to generic_make_request(), and | |
3138 | * uses that function to do most of the work. Both are fairly rough | |
3139 | * interfaces, @bio must be presetup and ready for I/O. | |
3140 | * | |
3141 | */ | |
3142 | void submit_bio(int rw, struct bio *bio) | |
3143 | { | |
3144 | int count = bio_sectors(bio); | |
3145 | ||
3146 | BIO_BUG_ON(!bio->bi_size); | |
3147 | BIO_BUG_ON(!bio->bi_io_vec); | |
22e2c507 | 3148 | bio->bi_rw |= rw; |
1da177e4 | 3149 | if (rw & WRITE) |
f8891e5e | 3150 | count_vm_events(PGPGOUT, count); |
1da177e4 | 3151 | else |
f8891e5e | 3152 | count_vm_events(PGPGIN, count); |
1da177e4 LT |
3153 | |
3154 | if (unlikely(block_dump)) { | |
3155 | char b[BDEVNAME_SIZE]; | |
3156 | printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n", | |
3157 | current->comm, current->pid, | |
3158 | (rw & WRITE) ? "WRITE" : "READ", | |
3159 | (unsigned long long)bio->bi_sector, | |
3160 | bdevname(bio->bi_bdev,b)); | |
3161 | } | |
3162 | ||
3163 | generic_make_request(bio); | |
3164 | } | |
3165 | ||
3166 | EXPORT_SYMBOL(submit_bio); | |
3167 | ||
93d17d3d | 3168 | static void blk_recalc_rq_segments(struct request *rq) |
1da177e4 LT |
3169 | { |
3170 | struct bio *bio, *prevbio = NULL; | |
3171 | int nr_phys_segs, nr_hw_segs; | |
3172 | unsigned int phys_size, hw_size; | |
3173 | request_queue_t *q = rq->q; | |
3174 | ||
3175 | if (!rq->bio) | |
3176 | return; | |
3177 | ||
3178 | phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0; | |
3179 | rq_for_each_bio(bio, rq) { | |
3180 | /* Force bio hw/phys segs to be recalculated. */ | |
3181 | bio->bi_flags &= ~(1 << BIO_SEG_VALID); | |
3182 | ||
3183 | nr_phys_segs += bio_phys_segments(q, bio); | |
3184 | nr_hw_segs += bio_hw_segments(q, bio); | |
3185 | if (prevbio) { | |
3186 | int pseg = phys_size + prevbio->bi_size + bio->bi_size; | |
3187 | int hseg = hw_size + prevbio->bi_size + bio->bi_size; | |
3188 | ||
3189 | if (blk_phys_contig_segment(q, prevbio, bio) && | |
3190 | pseg <= q->max_segment_size) { | |
3191 | nr_phys_segs--; | |
3192 | phys_size += prevbio->bi_size + bio->bi_size; | |
3193 | } else | |
3194 | phys_size = 0; | |
3195 | ||
3196 | if (blk_hw_contig_segment(q, prevbio, bio) && | |
3197 | hseg <= q->max_segment_size) { | |
3198 | nr_hw_segs--; | |
3199 | hw_size += prevbio->bi_size + bio->bi_size; | |
3200 | } else | |
3201 | hw_size = 0; | |
3202 | } | |
3203 | prevbio = bio; | |
3204 | } | |
3205 | ||
3206 | rq->nr_phys_segments = nr_phys_segs; | |
3207 | rq->nr_hw_segments = nr_hw_segs; | |
3208 | } | |
3209 | ||
93d17d3d | 3210 | static void blk_recalc_rq_sectors(struct request *rq, int nsect) |
1da177e4 LT |
3211 | { |
3212 | if (blk_fs_request(rq)) { | |
3213 | rq->hard_sector += nsect; | |
3214 | rq->hard_nr_sectors -= nsect; | |
3215 | ||
3216 | /* | |
3217 | * Move the I/O submission pointers ahead if required. | |
3218 | */ | |
3219 | if ((rq->nr_sectors >= rq->hard_nr_sectors) && | |
3220 | (rq->sector <= rq->hard_sector)) { | |
3221 | rq->sector = rq->hard_sector; | |
3222 | rq->nr_sectors = rq->hard_nr_sectors; | |
3223 | rq->hard_cur_sectors = bio_cur_sectors(rq->bio); | |
3224 | rq->current_nr_sectors = rq->hard_cur_sectors; | |
3225 | rq->buffer = bio_data(rq->bio); | |
3226 | } | |
3227 | ||
3228 | /* | |
3229 | * if total number of sectors is less than the first segment | |
3230 | * size, something has gone terribly wrong | |
3231 | */ | |
3232 | if (rq->nr_sectors < rq->current_nr_sectors) { | |
3233 | printk("blk: request botched\n"); | |
3234 | rq->nr_sectors = rq->current_nr_sectors; | |
3235 | } | |
3236 | } | |
3237 | } | |
3238 | ||
3239 | static int __end_that_request_first(struct request *req, int uptodate, | |
3240 | int nr_bytes) | |
3241 | { | |
3242 | int total_bytes, bio_nbytes, error, next_idx = 0; | |
3243 | struct bio *bio; | |
3244 | ||
2056a782 JA |
3245 | blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE); |
3246 | ||
1da177e4 LT |
3247 | /* |
3248 | * extend uptodate bool to allow < 0 value to be direct io error | |
3249 | */ | |
3250 | error = 0; | |
3251 | if (end_io_error(uptodate)) | |
3252 | error = !uptodate ? -EIO : uptodate; | |
3253 | ||
3254 | /* | |
3255 | * for a REQ_BLOCK_PC request, we want to carry any eventual | |
3256 | * sense key with us all the way through | |
3257 | */ | |
3258 | if (!blk_pc_request(req)) | |
3259 | req->errors = 0; | |
3260 | ||
3261 | if (!uptodate) { | |
4aff5e23 | 3262 | if (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET)) |
1da177e4 LT |
3263 | printk("end_request: I/O error, dev %s, sector %llu\n", |
3264 | req->rq_disk ? req->rq_disk->disk_name : "?", | |
3265 | (unsigned long long)req->sector); | |
3266 | } | |
3267 | ||
d72d904a | 3268 | if (blk_fs_request(req) && req->rq_disk) { |
a362357b JA |
3269 | const int rw = rq_data_dir(req); |
3270 | ||
53e86061 | 3271 | disk_stat_add(req->rq_disk, sectors[rw], nr_bytes >> 9); |
d72d904a JA |
3272 | } |
3273 | ||
1da177e4 LT |
3274 | total_bytes = bio_nbytes = 0; |
3275 | while ((bio = req->bio) != NULL) { | |
3276 | int nbytes; | |
3277 | ||
3278 | if (nr_bytes >= bio->bi_size) { | |
3279 | req->bio = bio->bi_next; | |
3280 | nbytes = bio->bi_size; | |
797e7dbb TH |
3281 | if (!ordered_bio_endio(req, bio, nbytes, error)) |
3282 | bio_endio(bio, nbytes, error); | |
1da177e4 LT |
3283 | next_idx = 0; |
3284 | bio_nbytes = 0; | |
3285 | } else { | |
3286 | int idx = bio->bi_idx + next_idx; | |
3287 | ||
3288 | if (unlikely(bio->bi_idx >= bio->bi_vcnt)) { | |
3289 | blk_dump_rq_flags(req, "__end_that"); | |
3290 | printk("%s: bio idx %d >= vcnt %d\n", | |
3291 | __FUNCTION__, | |
3292 | bio->bi_idx, bio->bi_vcnt); | |
3293 | break; | |
3294 | } | |
3295 | ||
3296 | nbytes = bio_iovec_idx(bio, idx)->bv_len; | |
3297 | BIO_BUG_ON(nbytes > bio->bi_size); | |
3298 | ||
3299 | /* | |
3300 | * not a complete bvec done | |
3301 | */ | |
3302 | if (unlikely(nbytes > nr_bytes)) { | |
3303 | bio_nbytes += nr_bytes; | |
3304 | total_bytes += nr_bytes; | |
3305 | break; | |
3306 | } | |
3307 | ||
3308 | /* | |
3309 | * advance to the next vector | |
3310 | */ | |
3311 | next_idx++; | |
3312 | bio_nbytes += nbytes; | |
3313 | } | |
3314 | ||
3315 | total_bytes += nbytes; | |
3316 | nr_bytes -= nbytes; | |
3317 | ||
3318 | if ((bio = req->bio)) { | |
3319 | /* | |
3320 | * end more in this run, or just return 'not-done' | |
3321 | */ | |
3322 | if (unlikely(nr_bytes <= 0)) | |
3323 | break; | |
3324 | } | |
3325 | } | |
3326 | ||
3327 | /* | |
3328 | * completely done | |
3329 | */ | |
3330 | if (!req->bio) | |
3331 | return 0; | |
3332 | ||
3333 | /* | |
3334 | * if the request wasn't completed, update state | |
3335 | */ | |
3336 | if (bio_nbytes) { | |
797e7dbb TH |
3337 | if (!ordered_bio_endio(req, bio, bio_nbytes, error)) |
3338 | bio_endio(bio, bio_nbytes, error); | |
1da177e4 LT |
3339 | bio->bi_idx += next_idx; |
3340 | bio_iovec(bio)->bv_offset += nr_bytes; | |
3341 | bio_iovec(bio)->bv_len -= nr_bytes; | |
3342 | } | |
3343 | ||
3344 | blk_recalc_rq_sectors(req, total_bytes >> 9); | |
3345 | blk_recalc_rq_segments(req); | |
3346 | return 1; | |
3347 | } | |
3348 | ||
3349 | /** | |
3350 | * end_that_request_first - end I/O on a request | |
3351 | * @req: the request being processed | |
3352 | * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error | |
3353 | * @nr_sectors: number of sectors to end I/O on | |
3354 | * | |
3355 | * Description: | |
3356 | * Ends I/O on a number of sectors attached to @req, and sets it up | |
3357 | * for the next range of segments (if any) in the cluster. | |
3358 | * | |
3359 | * Return: | |
3360 | * 0 - we are done with this request, call end_that_request_last() | |
3361 | * 1 - still buffers pending for this request | |
3362 | **/ | |
3363 | int end_that_request_first(struct request *req, int uptodate, int nr_sectors) | |
3364 | { | |
3365 | return __end_that_request_first(req, uptodate, nr_sectors << 9); | |
3366 | } | |
3367 | ||
3368 | EXPORT_SYMBOL(end_that_request_first); | |
3369 | ||
3370 | /** | |
3371 | * end_that_request_chunk - end I/O on a request | |
3372 | * @req: the request being processed | |
3373 | * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error | |
3374 | * @nr_bytes: number of bytes to complete | |
3375 | * | |
3376 | * Description: | |
3377 | * Ends I/O on a number of bytes attached to @req, and sets it up | |
3378 | * for the next range of segments (if any). Like end_that_request_first(), | |
3379 | * but deals with bytes instead of sectors. | |
3380 | * | |
3381 | * Return: | |
3382 | * 0 - we are done with this request, call end_that_request_last() | |
3383 | * 1 - still buffers pending for this request | |
3384 | **/ | |
3385 | int end_that_request_chunk(struct request *req, int uptodate, int nr_bytes) | |
3386 | { | |
3387 | return __end_that_request_first(req, uptodate, nr_bytes); | |
3388 | } | |
3389 | ||
3390 | EXPORT_SYMBOL(end_that_request_chunk); | |
3391 | ||
ff856bad JA |
3392 | /* |
3393 | * splice the completion data to a local structure and hand off to | |
3394 | * process_completion_queue() to complete the requests | |
3395 | */ | |
3396 | static void blk_done_softirq(struct softirq_action *h) | |
3397 | { | |
626ab0e6 | 3398 | struct list_head *cpu_list, local_list; |
ff856bad JA |
3399 | |
3400 | local_irq_disable(); | |
3401 | cpu_list = &__get_cpu_var(blk_cpu_done); | |
626ab0e6 | 3402 | list_replace_init(cpu_list, &local_list); |
ff856bad JA |
3403 | local_irq_enable(); |
3404 | ||
3405 | while (!list_empty(&local_list)) { | |
3406 | struct request *rq = list_entry(local_list.next, struct request, donelist); | |
3407 | ||
3408 | list_del_init(&rq->donelist); | |
3409 | rq->q->softirq_done_fn(rq); | |
3410 | } | |
3411 | } | |
3412 | ||
3413 | #ifdef CONFIG_HOTPLUG_CPU | |
3414 | ||
3415 | static int blk_cpu_notify(struct notifier_block *self, unsigned long action, | |
3416 | void *hcpu) | |
3417 | { | |
3418 | /* | |
3419 | * If a CPU goes away, splice its entries to the current CPU | |
3420 | * and trigger a run of the softirq | |
3421 | */ | |
3422 | if (action == CPU_DEAD) { | |
3423 | int cpu = (unsigned long) hcpu; | |
3424 | ||
3425 | local_irq_disable(); | |
3426 | list_splice_init(&per_cpu(blk_cpu_done, cpu), | |
3427 | &__get_cpu_var(blk_cpu_done)); | |
3428 | raise_softirq_irqoff(BLOCK_SOFTIRQ); | |
3429 | local_irq_enable(); | |
3430 | } | |
3431 | ||
3432 | return NOTIFY_OK; | |
3433 | } | |
3434 | ||
3435 | ||
054cc8a2 | 3436 | static struct notifier_block __devinitdata blk_cpu_notifier = { |
ff856bad JA |
3437 | .notifier_call = blk_cpu_notify, |
3438 | }; | |
3439 | ||
3440 | #endif /* CONFIG_HOTPLUG_CPU */ | |
3441 | ||
3442 | /** | |
3443 | * blk_complete_request - end I/O on a request | |
3444 | * @req: the request being processed | |
3445 | * | |
3446 | * Description: | |
3447 | * Ends all I/O on a request. It does not handle partial completions, | |
d6e05edc | 3448 | * unless the driver actually implements this in its completion callback |
ff856bad JA |
3449 | * through requeueing. Theh actual completion happens out-of-order, |
3450 | * through a softirq handler. The user must have registered a completion | |
3451 | * callback through blk_queue_softirq_done(). | |
3452 | **/ | |
3453 | ||
3454 | void blk_complete_request(struct request *req) | |
3455 | { | |
3456 | struct list_head *cpu_list; | |
3457 | unsigned long flags; | |
3458 | ||
3459 | BUG_ON(!req->q->softirq_done_fn); | |
3460 | ||
3461 | local_irq_save(flags); | |
3462 | ||
3463 | cpu_list = &__get_cpu_var(blk_cpu_done); | |
3464 | list_add_tail(&req->donelist, cpu_list); | |
3465 | raise_softirq_irqoff(BLOCK_SOFTIRQ); | |
3466 | ||
3467 | local_irq_restore(flags); | |
3468 | } | |
3469 | ||
3470 | EXPORT_SYMBOL(blk_complete_request); | |
3471 | ||
1da177e4 LT |
3472 | /* |
3473 | * queue lock must be held | |
3474 | */ | |
8ffdc655 | 3475 | void end_that_request_last(struct request *req, int uptodate) |
1da177e4 LT |
3476 | { |
3477 | struct gendisk *disk = req->rq_disk; | |
8ffdc655 TH |
3478 | int error; |
3479 | ||
3480 | /* | |
3481 | * extend uptodate bool to allow < 0 value to be direct io error | |
3482 | */ | |
3483 | error = 0; | |
3484 | if (end_io_error(uptodate)) | |
3485 | error = !uptodate ? -EIO : uptodate; | |
1da177e4 LT |
3486 | |
3487 | if (unlikely(laptop_mode) && blk_fs_request(req)) | |
3488 | laptop_io_completion(); | |
3489 | ||
fd0ff8aa JA |
3490 | /* |
3491 | * Account IO completion. bar_rq isn't accounted as a normal | |
3492 | * IO on queueing nor completion. Accounting the containing | |
3493 | * request is enough. | |
3494 | */ | |
3495 | if (disk && blk_fs_request(req) && req != &req->q->bar_rq) { | |
1da177e4 | 3496 | unsigned long duration = jiffies - req->start_time; |
a362357b JA |
3497 | const int rw = rq_data_dir(req); |
3498 | ||
3499 | __disk_stat_inc(disk, ios[rw]); | |
3500 | __disk_stat_add(disk, ticks[rw], duration); | |
1da177e4 LT |
3501 | disk_round_stats(disk); |
3502 | disk->in_flight--; | |
3503 | } | |
3504 | if (req->end_io) | |
8ffdc655 | 3505 | req->end_io(req, error); |
1da177e4 LT |
3506 | else |
3507 | __blk_put_request(req->q, req); | |
3508 | } | |
3509 | ||
3510 | EXPORT_SYMBOL(end_that_request_last); | |
3511 | ||
3512 | void end_request(struct request *req, int uptodate) | |
3513 | { | |
3514 | if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) { | |
3515 | add_disk_randomness(req->rq_disk); | |
3516 | blkdev_dequeue_request(req); | |
8ffdc655 | 3517 | end_that_request_last(req, uptodate); |
1da177e4 LT |
3518 | } |
3519 | } | |
3520 | ||
3521 | EXPORT_SYMBOL(end_request); | |
3522 | ||
3523 | void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio) | |
3524 | { | |
4aff5e23 JA |
3525 | /* first two bits are identical in rq->cmd_flags and bio->bi_rw */ |
3526 | rq->cmd_flags |= (bio->bi_rw & 3); | |
1da177e4 LT |
3527 | |
3528 | rq->nr_phys_segments = bio_phys_segments(q, bio); | |
3529 | rq->nr_hw_segments = bio_hw_segments(q, bio); | |
3530 | rq->current_nr_sectors = bio_cur_sectors(bio); | |
3531 | rq->hard_cur_sectors = rq->current_nr_sectors; | |
3532 | rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio); | |
3533 | rq->buffer = bio_data(bio); | |
3534 | ||
3535 | rq->bio = rq->biotail = bio; | |
3536 | } | |
3537 | ||
3538 | EXPORT_SYMBOL(blk_rq_bio_prep); | |
3539 | ||
3540 | int kblockd_schedule_work(struct work_struct *work) | |
3541 | { | |
3542 | return queue_work(kblockd_workqueue, work); | |
3543 | } | |
3544 | ||
3545 | EXPORT_SYMBOL(kblockd_schedule_work); | |
3546 | ||
3547 | void kblockd_flush(void) | |
3548 | { | |
3549 | flush_workqueue(kblockd_workqueue); | |
3550 | } | |
3551 | EXPORT_SYMBOL(kblockd_flush); | |
3552 | ||
3553 | int __init blk_dev_init(void) | |
3554 | { | |
ff856bad JA |
3555 | int i; |
3556 | ||
1da177e4 LT |
3557 | kblockd_workqueue = create_workqueue("kblockd"); |
3558 | if (!kblockd_workqueue) | |
3559 | panic("Failed to create kblockd\n"); | |
3560 | ||
3561 | request_cachep = kmem_cache_create("blkdev_requests", | |
3562 | sizeof(struct request), 0, SLAB_PANIC, NULL, NULL); | |
3563 | ||
3564 | requestq_cachep = kmem_cache_create("blkdev_queue", | |
3565 | sizeof(request_queue_t), 0, SLAB_PANIC, NULL, NULL); | |
3566 | ||
3567 | iocontext_cachep = kmem_cache_create("blkdev_ioc", | |
3568 | sizeof(struct io_context), 0, SLAB_PANIC, NULL, NULL); | |
3569 | ||
0a945022 | 3570 | for_each_possible_cpu(i) |
ff856bad JA |
3571 | INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i)); |
3572 | ||
3573 | open_softirq(BLOCK_SOFTIRQ, blk_done_softirq, NULL); | |
5a67e4c5 | 3574 | register_hotcpu_notifier(&blk_cpu_notifier); |
ff856bad | 3575 | |
1da177e4 LT |
3576 | blk_max_low_pfn = max_low_pfn; |
3577 | blk_max_pfn = max_pfn; | |
3578 | ||
3579 | return 0; | |
3580 | } | |
3581 | ||
3582 | /* | |
3583 | * IO Context helper functions | |
3584 | */ | |
3585 | void put_io_context(struct io_context *ioc) | |
3586 | { | |
3587 | if (ioc == NULL) | |
3588 | return; | |
3589 | ||
3590 | BUG_ON(atomic_read(&ioc->refcount) == 0); | |
3591 | ||
3592 | if (atomic_dec_and_test(&ioc->refcount)) { | |
e2d74ac0 JA |
3593 | struct cfq_io_context *cic; |
3594 | ||
334e94de | 3595 | rcu_read_lock(); |
1da177e4 LT |
3596 | if (ioc->aic && ioc->aic->dtor) |
3597 | ioc->aic->dtor(ioc->aic); | |
e2d74ac0 | 3598 | if (ioc->cic_root.rb_node != NULL) { |
7143dd4b JA |
3599 | struct rb_node *n = rb_first(&ioc->cic_root); |
3600 | ||
3601 | cic = rb_entry(n, struct cfq_io_context, rb_node); | |
e2d74ac0 JA |
3602 | cic->dtor(ioc); |
3603 | } | |
334e94de | 3604 | rcu_read_unlock(); |
1da177e4 LT |
3605 | |
3606 | kmem_cache_free(iocontext_cachep, ioc); | |
3607 | } | |
3608 | } | |
3609 | EXPORT_SYMBOL(put_io_context); | |
3610 | ||
3611 | /* Called by the exitting task */ | |
3612 | void exit_io_context(void) | |
3613 | { | |
3614 | unsigned long flags; | |
3615 | struct io_context *ioc; | |
e2d74ac0 | 3616 | struct cfq_io_context *cic; |
1da177e4 LT |
3617 | |
3618 | local_irq_save(flags); | |
22e2c507 | 3619 | task_lock(current); |
1da177e4 LT |
3620 | ioc = current->io_context; |
3621 | current->io_context = NULL; | |
22e2c507 JA |
3622 | ioc->task = NULL; |
3623 | task_unlock(current); | |
1da177e4 LT |
3624 | local_irq_restore(flags); |
3625 | ||
3626 | if (ioc->aic && ioc->aic->exit) | |
3627 | ioc->aic->exit(ioc->aic); | |
e2d74ac0 JA |
3628 | if (ioc->cic_root.rb_node != NULL) { |
3629 | cic = rb_entry(rb_first(&ioc->cic_root), struct cfq_io_context, rb_node); | |
3630 | cic->exit(ioc); | |
3631 | } | |
3632 | ||
1da177e4 LT |
3633 | put_io_context(ioc); |
3634 | } | |
3635 | ||
3636 | /* | |
3637 | * If the current task has no IO context then create one and initialise it. | |
fb3cc432 | 3638 | * Otherwise, return its existing IO context. |
1da177e4 | 3639 | * |
fb3cc432 NP |
3640 | * This returned IO context doesn't have a specifically elevated refcount, |
3641 | * but since the current task itself holds a reference, the context can be | |
3642 | * used in general code, so long as it stays within `current` context. | |
1da177e4 | 3643 | */ |
8267e268 | 3644 | struct io_context *current_io_context(gfp_t gfp_flags) |
1da177e4 LT |
3645 | { |
3646 | struct task_struct *tsk = current; | |
1da177e4 LT |
3647 | struct io_context *ret; |
3648 | ||
1da177e4 | 3649 | ret = tsk->io_context; |
fb3cc432 NP |
3650 | if (likely(ret)) |
3651 | return ret; | |
1da177e4 LT |
3652 | |
3653 | ret = kmem_cache_alloc(iocontext_cachep, gfp_flags); | |
3654 | if (ret) { | |
3655 | atomic_set(&ret->refcount, 1); | |
22e2c507 | 3656 | ret->task = current; |
fc46379d | 3657 | ret->ioprio_changed = 0; |
1da177e4 LT |
3658 | ret->last_waited = jiffies; /* doesn't matter... */ |
3659 | ret->nr_batch_requests = 0; /* because this is 0 */ | |
3660 | ret->aic = NULL; | |
e2d74ac0 | 3661 | ret->cic_root.rb_node = NULL; |
9f83e45e ON |
3662 | /* make sure set_task_ioprio() sees the settings above */ |
3663 | smp_wmb(); | |
fb3cc432 NP |
3664 | tsk->io_context = ret; |
3665 | } | |
1da177e4 | 3666 | |
fb3cc432 NP |
3667 | return ret; |
3668 | } | |
3669 | EXPORT_SYMBOL(current_io_context); | |
1da177e4 | 3670 | |
fb3cc432 NP |
3671 | /* |
3672 | * If the current task has no IO context then create one and initialise it. | |
3673 | * If it does have a context, take a ref on it. | |
3674 | * | |
3675 | * This is always called in the context of the task which submitted the I/O. | |
3676 | */ | |
8267e268 | 3677 | struct io_context *get_io_context(gfp_t gfp_flags) |
fb3cc432 NP |
3678 | { |
3679 | struct io_context *ret; | |
3680 | ret = current_io_context(gfp_flags); | |
3681 | if (likely(ret)) | |
1da177e4 | 3682 | atomic_inc(&ret->refcount); |
1da177e4 LT |
3683 | return ret; |
3684 | } | |
3685 | EXPORT_SYMBOL(get_io_context); | |
3686 | ||
3687 | void copy_io_context(struct io_context **pdst, struct io_context **psrc) | |
3688 | { | |
3689 | struct io_context *src = *psrc; | |
3690 | struct io_context *dst = *pdst; | |
3691 | ||
3692 | if (src) { | |
3693 | BUG_ON(atomic_read(&src->refcount) == 0); | |
3694 | atomic_inc(&src->refcount); | |
3695 | put_io_context(dst); | |
3696 | *pdst = src; | |
3697 | } | |
3698 | } | |
3699 | EXPORT_SYMBOL(copy_io_context); | |
3700 | ||
3701 | void swap_io_context(struct io_context **ioc1, struct io_context **ioc2) | |
3702 | { | |
3703 | struct io_context *temp; | |
3704 | temp = *ioc1; | |
3705 | *ioc1 = *ioc2; | |
3706 | *ioc2 = temp; | |
3707 | } | |
3708 | EXPORT_SYMBOL(swap_io_context); | |
3709 | ||
3710 | /* | |
3711 | * sysfs parts below | |
3712 | */ | |
3713 | struct queue_sysfs_entry { | |
3714 | struct attribute attr; | |
3715 | ssize_t (*show)(struct request_queue *, char *); | |
3716 | ssize_t (*store)(struct request_queue *, const char *, size_t); | |
3717 | }; | |
3718 | ||
3719 | static ssize_t | |
3720 | queue_var_show(unsigned int var, char *page) | |
3721 | { | |
3722 | return sprintf(page, "%d\n", var); | |
3723 | } | |
3724 | ||
3725 | static ssize_t | |
3726 | queue_var_store(unsigned long *var, const char *page, size_t count) | |
3727 | { | |
3728 | char *p = (char *) page; | |
3729 | ||
3730 | *var = simple_strtoul(p, &p, 10); | |
3731 | return count; | |
3732 | } | |
3733 | ||
3734 | static ssize_t queue_requests_show(struct request_queue *q, char *page) | |
3735 | { | |
3736 | return queue_var_show(q->nr_requests, (page)); | |
3737 | } | |
3738 | ||
3739 | static ssize_t | |
3740 | queue_requests_store(struct request_queue *q, const char *page, size_t count) | |
3741 | { | |
3742 | struct request_list *rl = &q->rq; | |
c981ff9f AV |
3743 | unsigned long nr; |
3744 | int ret = queue_var_store(&nr, page, count); | |
3745 | if (nr < BLKDEV_MIN_RQ) | |
3746 | nr = BLKDEV_MIN_RQ; | |
1da177e4 | 3747 | |
c981ff9f AV |
3748 | spin_lock_irq(q->queue_lock); |
3749 | q->nr_requests = nr; | |
1da177e4 LT |
3750 | blk_queue_congestion_threshold(q); |
3751 | ||
3752 | if (rl->count[READ] >= queue_congestion_on_threshold(q)) | |
3753 | set_queue_congested(q, READ); | |
3754 | else if (rl->count[READ] < queue_congestion_off_threshold(q)) | |
3755 | clear_queue_congested(q, READ); | |
3756 | ||
3757 | if (rl->count[WRITE] >= queue_congestion_on_threshold(q)) | |
3758 | set_queue_congested(q, WRITE); | |
3759 | else if (rl->count[WRITE] < queue_congestion_off_threshold(q)) | |
3760 | clear_queue_congested(q, WRITE); | |
3761 | ||
3762 | if (rl->count[READ] >= q->nr_requests) { | |
3763 | blk_set_queue_full(q, READ); | |
3764 | } else if (rl->count[READ]+1 <= q->nr_requests) { | |
3765 | blk_clear_queue_full(q, READ); | |
3766 | wake_up(&rl->wait[READ]); | |
3767 | } | |
3768 | ||
3769 | if (rl->count[WRITE] >= q->nr_requests) { | |
3770 | blk_set_queue_full(q, WRITE); | |
3771 | } else if (rl->count[WRITE]+1 <= q->nr_requests) { | |
3772 | blk_clear_queue_full(q, WRITE); | |
3773 | wake_up(&rl->wait[WRITE]); | |
3774 | } | |
c981ff9f | 3775 | spin_unlock_irq(q->queue_lock); |
1da177e4 LT |
3776 | return ret; |
3777 | } | |
3778 | ||
3779 | static ssize_t queue_ra_show(struct request_queue *q, char *page) | |
3780 | { | |
3781 | int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10); | |
3782 | ||
3783 | return queue_var_show(ra_kb, (page)); | |
3784 | } | |
3785 | ||
3786 | static ssize_t | |
3787 | queue_ra_store(struct request_queue *q, const char *page, size_t count) | |
3788 | { | |
3789 | unsigned long ra_kb; | |
3790 | ssize_t ret = queue_var_store(&ra_kb, page, count); | |
3791 | ||
3792 | spin_lock_irq(q->queue_lock); | |
3793 | if (ra_kb > (q->max_sectors >> 1)) | |
3794 | ra_kb = (q->max_sectors >> 1); | |
3795 | ||
3796 | q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10); | |
3797 | spin_unlock_irq(q->queue_lock); | |
3798 | ||
3799 | return ret; | |
3800 | } | |
3801 | ||
3802 | static ssize_t queue_max_sectors_show(struct request_queue *q, char *page) | |
3803 | { | |
3804 | int max_sectors_kb = q->max_sectors >> 1; | |
3805 | ||
3806 | return queue_var_show(max_sectors_kb, (page)); | |
3807 | } | |
3808 | ||
3809 | static ssize_t | |
3810 | queue_max_sectors_store(struct request_queue *q, const char *page, size_t count) | |
3811 | { | |
3812 | unsigned long max_sectors_kb, | |
3813 | max_hw_sectors_kb = q->max_hw_sectors >> 1, | |
3814 | page_kb = 1 << (PAGE_CACHE_SHIFT - 10); | |
3815 | ssize_t ret = queue_var_store(&max_sectors_kb, page, count); | |
3816 | int ra_kb; | |
3817 | ||
3818 | if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb) | |
3819 | return -EINVAL; | |
3820 | /* | |
3821 | * Take the queue lock to update the readahead and max_sectors | |
3822 | * values synchronously: | |
3823 | */ | |
3824 | spin_lock_irq(q->queue_lock); | |
3825 | /* | |
3826 | * Trim readahead window as well, if necessary: | |
3827 | */ | |
3828 | ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10); | |
3829 | if (ra_kb > max_sectors_kb) | |
3830 | q->backing_dev_info.ra_pages = | |
3831 | max_sectors_kb >> (PAGE_CACHE_SHIFT - 10); | |
3832 | ||
3833 | q->max_sectors = max_sectors_kb << 1; | |
3834 | spin_unlock_irq(q->queue_lock); | |
3835 | ||
3836 | return ret; | |
3837 | } | |
3838 | ||
3839 | static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page) | |
3840 | { | |
3841 | int max_hw_sectors_kb = q->max_hw_sectors >> 1; | |
3842 | ||
3843 | return queue_var_show(max_hw_sectors_kb, (page)); | |
3844 | } | |
3845 | ||
3846 | ||
3847 | static struct queue_sysfs_entry queue_requests_entry = { | |
3848 | .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR }, | |
3849 | .show = queue_requests_show, | |
3850 | .store = queue_requests_store, | |
3851 | }; | |
3852 | ||
3853 | static struct queue_sysfs_entry queue_ra_entry = { | |
3854 | .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR }, | |
3855 | .show = queue_ra_show, | |
3856 | .store = queue_ra_store, | |
3857 | }; | |
3858 | ||
3859 | static struct queue_sysfs_entry queue_max_sectors_entry = { | |
3860 | .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR }, | |
3861 | .show = queue_max_sectors_show, | |
3862 | .store = queue_max_sectors_store, | |
3863 | }; | |
3864 | ||
3865 | static struct queue_sysfs_entry queue_max_hw_sectors_entry = { | |
3866 | .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO }, | |
3867 | .show = queue_max_hw_sectors_show, | |
3868 | }; | |
3869 | ||
3870 | static struct queue_sysfs_entry queue_iosched_entry = { | |
3871 | .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR }, | |
3872 | .show = elv_iosched_show, | |
3873 | .store = elv_iosched_store, | |
3874 | }; | |
3875 | ||
3876 | static struct attribute *default_attrs[] = { | |
3877 | &queue_requests_entry.attr, | |
3878 | &queue_ra_entry.attr, | |
3879 | &queue_max_hw_sectors_entry.attr, | |
3880 | &queue_max_sectors_entry.attr, | |
3881 | &queue_iosched_entry.attr, | |
3882 | NULL, | |
3883 | }; | |
3884 | ||
3885 | #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr) | |
3886 | ||
3887 | static ssize_t | |
3888 | queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
3889 | { | |
3890 | struct queue_sysfs_entry *entry = to_queue(attr); | |
483f4afc AV |
3891 | request_queue_t *q = container_of(kobj, struct request_queue, kobj); |
3892 | ssize_t res; | |
1da177e4 | 3893 | |
1da177e4 | 3894 | if (!entry->show) |
6c1852a0 | 3895 | return -EIO; |
483f4afc AV |
3896 | mutex_lock(&q->sysfs_lock); |
3897 | if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) { | |
3898 | mutex_unlock(&q->sysfs_lock); | |
3899 | return -ENOENT; | |
3900 | } | |
3901 | res = entry->show(q, page); | |
3902 | mutex_unlock(&q->sysfs_lock); | |
3903 | return res; | |
1da177e4 LT |
3904 | } |
3905 | ||
3906 | static ssize_t | |
3907 | queue_attr_store(struct kobject *kobj, struct attribute *attr, | |
3908 | const char *page, size_t length) | |
3909 | { | |
3910 | struct queue_sysfs_entry *entry = to_queue(attr); | |
483f4afc AV |
3911 | request_queue_t *q = container_of(kobj, struct request_queue, kobj); |
3912 | ||
3913 | ssize_t res; | |
1da177e4 | 3914 | |
1da177e4 | 3915 | if (!entry->store) |
6c1852a0 | 3916 | return -EIO; |
483f4afc AV |
3917 | mutex_lock(&q->sysfs_lock); |
3918 | if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) { | |
3919 | mutex_unlock(&q->sysfs_lock); | |
3920 | return -ENOENT; | |
3921 | } | |
3922 | res = entry->store(q, page, length); | |
3923 | mutex_unlock(&q->sysfs_lock); | |
3924 | return res; | |
1da177e4 LT |
3925 | } |
3926 | ||
3927 | static struct sysfs_ops queue_sysfs_ops = { | |
3928 | .show = queue_attr_show, | |
3929 | .store = queue_attr_store, | |
3930 | }; | |
3931 | ||
93d17d3d | 3932 | static struct kobj_type queue_ktype = { |
1da177e4 LT |
3933 | .sysfs_ops = &queue_sysfs_ops, |
3934 | .default_attrs = default_attrs, | |
483f4afc | 3935 | .release = blk_release_queue, |
1da177e4 LT |
3936 | }; |
3937 | ||
3938 | int blk_register_queue(struct gendisk *disk) | |
3939 | { | |
3940 | int ret; | |
3941 | ||
3942 | request_queue_t *q = disk->queue; | |
3943 | ||
3944 | if (!q || !q->request_fn) | |
3945 | return -ENXIO; | |
3946 | ||
3947 | q->kobj.parent = kobject_get(&disk->kobj); | |
1da177e4 | 3948 | |
483f4afc | 3949 | ret = kobject_add(&q->kobj); |
1da177e4 LT |
3950 | if (ret < 0) |
3951 | return ret; | |
3952 | ||
483f4afc AV |
3953 | kobject_uevent(&q->kobj, KOBJ_ADD); |
3954 | ||
1da177e4 LT |
3955 | ret = elv_register_queue(q); |
3956 | if (ret) { | |
483f4afc AV |
3957 | kobject_uevent(&q->kobj, KOBJ_REMOVE); |
3958 | kobject_del(&q->kobj); | |
1da177e4 LT |
3959 | return ret; |
3960 | } | |
3961 | ||
3962 | return 0; | |
3963 | } | |
3964 | ||
3965 | void blk_unregister_queue(struct gendisk *disk) | |
3966 | { | |
3967 | request_queue_t *q = disk->queue; | |
3968 | ||
3969 | if (q && q->request_fn) { | |
3970 | elv_unregister_queue(q); | |
3971 | ||
483f4afc AV |
3972 | kobject_uevent(&q->kobj, KOBJ_REMOVE); |
3973 | kobject_del(&q->kobj); | |
1da177e4 LT |
3974 | kobject_put(&disk->kobj); |
3975 | } | |
3976 | } |