1
2
3
4#include <linux/kernel.h>
5#include <linux/module.h>
6#include <linux/bio.h>
7#include <linux/blkdev.h>
8#include <linux/scatterlist.h>
9
10#include "blk.h"
11
12static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
13 struct bio *bio)
14{
15 struct bio_vec *bv, *bvprv = NULL;
16 int cluster, i, high, highprv = 1;
17 unsigned int seg_size, nr_phys_segs;
18 struct bio *fbio, *bbio;
19
20 if (!bio)
21 return 0;
22
23 fbio = bio;
24 cluster = blk_queue_cluster(q);
25 seg_size = 0;
26 nr_phys_segs = 0;
27 for_each_bio(bio) {
28 bio_for_each_segment(bv, bio, i) {
29
30
31
32
33
34 high = page_to_pfn(bv->bv_page) > queue_bounce_pfn(q);
35 if (high || highprv)
36 goto new_segment;
37 if (cluster) {
38 if (seg_size + bv->bv_len
39 > queue_max_segment_size(q))
40 goto new_segment;
41 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
42 goto new_segment;
43 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
44 goto new_segment;
45
46 seg_size += bv->bv_len;
47 bvprv = bv;
48 continue;
49 }
50new_segment:
51 if (nr_phys_segs == 1 && seg_size >
52 fbio->bi_seg_front_size)
53 fbio->bi_seg_front_size = seg_size;
54
55 nr_phys_segs++;
56 bvprv = bv;
57 seg_size = bv->bv_len;
58 highprv = high;
59 }
60 bbio = bio;
61 }
62
63 if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size)
64 fbio->bi_seg_front_size = seg_size;
65 if (seg_size > bbio->bi_seg_back_size)
66 bbio->bi_seg_back_size = seg_size;
67
68 return nr_phys_segs;
69}
70
71void blk_recalc_rq_segments(struct request *rq)
72{
73 rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio);
74}
75
76void blk_recount_segments(struct request_queue *q, struct bio *bio)
77{
78 struct bio *nxt = bio->bi_next;
79
80 bio->bi_next = NULL;
81 bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio);
82 bio->bi_next = nxt;
83 bio->bi_flags |= (1 << BIO_SEG_VALID);
84}
85EXPORT_SYMBOL(blk_recount_segments);
86
87static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
88 struct bio *nxt)
89{
90 if (!blk_queue_cluster(q))
91 return 0;
92
93 if (bio->bi_seg_back_size + nxt->bi_seg_front_size >
94 queue_max_segment_size(q))
95 return 0;
96
97 if (!bio_has_data(bio))
98 return 1;
99
100 if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
101 return 0;
102
103
104
105
106
107 if (BIO_SEG_BOUNDARY(q, bio, nxt))
108 return 1;
109
110 return 0;
111}
112
113static void
114__blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec,
115 struct scatterlist *sglist, struct bio_vec **bvprv,
116 struct scatterlist **sg, int *nsegs, int *cluster)
117{
118
119 int nbytes = bvec->bv_len;
120
121 if (*bvprv && *cluster) {
122 if ((*sg)->length + nbytes > queue_max_segment_size(q))
123 goto new_segment;
124
125 if (!BIOVEC_PHYS_MERGEABLE(*bvprv, bvec))
126 goto new_segment;
127 if (!BIOVEC_SEG_BOUNDARY(q, *bvprv, bvec))
128 goto new_segment;
129
130 (*sg)->length += nbytes;
131 } else {
132new_segment:
133 if (!*sg)
134 *sg = sglist;
135 else {
136
137
138
139
140
141
142
143
144
145
146 sg_unmark_end(*sg);
147 *sg = sg_next(*sg);
148 }
149
150 sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset);
151 (*nsegs)++;
152 }
153 *bvprv = bvec;
154}
155
156
157
158
159
160int blk_rq_map_sg(struct request_queue *q, struct request *rq,
161 struct scatterlist *sglist)
162{
163 struct bio_vec *bvec, *bvprv;
164 struct req_iterator iter;
165 struct scatterlist *sg;
166 int nsegs, cluster;
167
168 nsegs = 0;
169 cluster = blk_queue_cluster(q);
170
171
172
173
174 bvprv = NULL;
175 sg = NULL;
176 rq_for_each_segment(bvec, rq, iter) {
177 __blk_segment_map_sg(q, bvec, sglist, &bvprv, &sg,
178 &nsegs, &cluster);
179 }
180
181
182 if (unlikely(rq->cmd_flags & REQ_COPY_USER) &&
183 (blk_rq_bytes(rq) & q->dma_pad_mask)) {
184 unsigned int pad_len =
185 (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1;
186
187 sg->length += pad_len;
188 rq->extra_len += pad_len;
189 }
190
191 if (q->dma_drain_size && q->dma_drain_needed(rq)) {
192 if (rq->cmd_flags & REQ_WRITE)
193 memset(q->dma_drain_buffer, 0, q->dma_drain_size);
194
195 sg->page_link &= ~0x02;
196 sg = sg_next(sg);
197 sg_set_page(sg, virt_to_page(q->dma_drain_buffer),
198 q->dma_drain_size,
199 ((unsigned long)q->dma_drain_buffer) &
200 (PAGE_SIZE - 1));
201 nsegs++;
202 rq->extra_len += q->dma_drain_size;
203 }
204
205 if (sg)
206 sg_mark_end(sg);
207
208 return nsegs;
209}
210EXPORT_SYMBOL(blk_rq_map_sg);
211
212
213
214
215
216
217
218
219
220
221
222
223int blk_bio_map_sg(struct request_queue *q, struct bio *bio,
224 struct scatterlist *sglist)
225{
226 struct bio_vec *bvec, *bvprv;
227 struct scatterlist *sg;
228 int nsegs, cluster;
229 unsigned long i;
230
231 nsegs = 0;
232 cluster = blk_queue_cluster(q);
233
234 bvprv = NULL;
235 sg = NULL;
236 bio_for_each_segment(bvec, bio, i) {
237 __blk_segment_map_sg(q, bvec, sglist, &bvprv, &sg,
238 &nsegs, &cluster);
239 }
240
241 if (sg)
242 sg_mark_end(sg);
243
244 BUG_ON(bio->bi_phys_segments && nsegs > bio->bi_phys_segments);
245 return nsegs;
246}
247EXPORT_SYMBOL(blk_bio_map_sg);
248
249static inline int ll_new_hw_segment(struct request_queue *q,
250 struct request *req,
251 struct bio *bio)
252{
253 int nr_phys_segs = bio_phys_segments(q, bio);
254
255 if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q))
256 goto no_merge;
257
258 if (bio_integrity(bio) && blk_integrity_merge_bio(q, req, bio))
259 goto no_merge;
260
261
262
263
264
265 req->nr_phys_segments += nr_phys_segs;
266 return 1;
267
268no_merge:
269 req->cmd_flags |= REQ_NOMERGE;
270 if (req == q->last_merge)
271 q->last_merge = NULL;
272 return 0;
273}
274
275int ll_back_merge_fn(struct request_queue *q, struct request *req,
276 struct bio *bio)
277{
278 if (blk_rq_sectors(req) + bio_sectors(bio) >
279 blk_rq_get_max_sectors(req)) {
280 req->cmd_flags |= REQ_NOMERGE;
281 if (req == q->last_merge)
282 q->last_merge = NULL;
283 return 0;
284 }
285 if (!bio_flagged(req->biotail, BIO_SEG_VALID))
286 blk_recount_segments(q, req->biotail);
287 if (!bio_flagged(bio, BIO_SEG_VALID))
288 blk_recount_segments(q, bio);
289
290 return ll_new_hw_segment(q, req, bio);
291}
292
293int ll_front_merge_fn(struct request_queue *q, struct request *req,
294 struct bio *bio)
295{
296 if (blk_rq_sectors(req) + bio_sectors(bio) >
297 blk_rq_get_max_sectors(req)) {
298 req->cmd_flags |= REQ_NOMERGE;
299 if (req == q->last_merge)
300 q->last_merge = NULL;
301 return 0;
302 }
303 if (!bio_flagged(bio, BIO_SEG_VALID))
304 blk_recount_segments(q, bio);
305 if (!bio_flagged(req->bio, BIO_SEG_VALID))
306 blk_recount_segments(q, req->bio);
307
308 return ll_new_hw_segment(q, req, bio);
309}
310
311
312
313
314
315static bool req_no_special_merge(struct request *req)
316{
317 struct request_queue *q = req->q;
318
319 return !q->mq_ops && req->special;
320}
321
322static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
323 struct request *next)
324{
325 int total_phys_segments;
326 unsigned int seg_size =
327 req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size;
328
329
330
331
332
333 if (req_no_special_merge(req) || req_no_special_merge(next))
334 return 0;
335
336
337
338
339 if ((blk_rq_sectors(req) + blk_rq_sectors(next)) >
340 blk_rq_get_max_sectors(req))
341 return 0;
342
343 total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
344 if (blk_phys_contig_segment(q, req->biotail, next->bio)) {
345 if (req->nr_phys_segments == 1)
346 req->bio->bi_seg_front_size = seg_size;
347 if (next->nr_phys_segments == 1)
348 next->biotail->bi_seg_back_size = seg_size;
349 total_phys_segments--;
350 }
351
352 if (total_phys_segments > queue_max_segments(q))
353 return 0;
354
355 if (blk_integrity_rq(req) && blk_integrity_merge_rq(q, req, next))
356 return 0;
357
358
359 req->nr_phys_segments = total_phys_segments;
360 return 1;
361}
362
363
364
365
366
367
368
369
370
371
372void blk_rq_set_mixed_merge(struct request *rq)
373{
374 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
375 struct bio *bio;
376
377 if (rq->cmd_flags & REQ_MIXED_MERGE)
378 return;
379
380
381
382
383
384
385 for (bio = rq->bio; bio; bio = bio->bi_next) {
386 WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) &&
387 (bio->bi_rw & REQ_FAILFAST_MASK) != ff);
388 bio->bi_rw |= ff;
389 }
390 rq->cmd_flags |= REQ_MIXED_MERGE;
391}
392
393static void blk_account_io_merge(struct request *req)
394{
395 if (blk_do_io_stat(req)) {
396 struct hd_struct *part;
397 int cpu;
398
399 cpu = part_stat_lock();
400 part = req->part;
401
402 part_round_stats(cpu, part);
403 part_dec_in_flight(part, rq_data_dir(req));
404
405 hd_struct_put(part);
406 part_stat_unlock();
407 }
408}
409
410
411
412
413static int attempt_merge(struct request_queue *q, struct request *req,
414 struct request *next)
415{
416 if (!rq_mergeable(req) || !rq_mergeable(next))
417 return 0;
418
419 if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags))
420 return 0;
421
422
423
424
425 if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next))
426 return 0;
427
428 if (rq_data_dir(req) != rq_data_dir(next)
429 || req->rq_disk != next->rq_disk
430 || req_no_special_merge(next))
431 return 0;
432
433 if (req->cmd_flags & REQ_WRITE_SAME &&
434 !blk_write_same_mergeable(req->bio, next->bio))
435 return 0;
436
437
438
439
440
441
442
443 if (!ll_merge_requests_fn(q, req, next))
444 return 0;
445
446
447
448
449
450
451
452 if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE ||
453 (req->cmd_flags & REQ_FAILFAST_MASK) !=
454 (next->cmd_flags & REQ_FAILFAST_MASK)) {
455 blk_rq_set_mixed_merge(req);
456 blk_rq_set_mixed_merge(next);
457 }
458
459
460
461
462
463
464
465 if (time_after(req->start_time, next->start_time))
466 req->start_time = next->start_time;
467
468 req->biotail->bi_next = next->bio;
469 req->biotail = next->biotail;
470
471 req->__data_len += blk_rq_bytes(next);
472
473 elv_merge_requests(q, req, next);
474
475
476
477
478 blk_account_io_merge(next);
479
480 req->ioprio = ioprio_best(req->ioprio, next->ioprio);
481 if (blk_rq_cpu_valid(next))
482 req->cpu = next->cpu;
483
484
485 next->bio = NULL;
486 __blk_put_request(q, next);
487 return 1;
488}
489
490int attempt_back_merge(struct request_queue *q, struct request *rq)
491{
492 struct request *next = elv_latter_request(q, rq);
493
494 if (next)
495 return attempt_merge(q, rq, next);
496
497 return 0;
498}
499
500int attempt_front_merge(struct request_queue *q, struct request *rq)
501{
502 struct request *prev = elv_former_request(q, rq);
503
504 if (prev)
505 return attempt_merge(q, prev, rq);
506
507 return 0;
508}
509
510int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
511 struct request *next)
512{
513 return attempt_merge(q, rq, next);
514}
515
516bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
517{
518 if (!rq_mergeable(rq) || !bio_mergeable(bio))
519 return false;
520
521 if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw))
522 return false;
523
524
525 if (bio_data_dir(bio) != rq_data_dir(rq))
526 return false;
527
528
529 if (rq->rq_disk != bio->bi_bdev->bd_disk || req_no_special_merge(rq))
530 return false;
531
532
533 if (bio_integrity(bio) != blk_integrity_rq(rq))
534 return false;
535
536
537 if (rq->cmd_flags & REQ_WRITE_SAME &&
538 !blk_write_same_mergeable(rq->bio, bio))
539 return false;
540
541 return true;
542}
543
544int blk_try_merge(struct request *rq, struct bio *bio)
545{
546 if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_sector)
547 return ELEVATOR_BACK_MERGE;
548 else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_sector)
549 return ELEVATOR_FRONT_MERGE;
550 return ELEVATOR_NO_MERGE;
551}
552