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 bool no_sg_merge)
15{
16 struct bio_vec bv, bvprv = { NULL };
17 int cluster, high, highprv = 1;
18 unsigned int seg_size, nr_phys_segs;
19 struct bio *fbio, *bbio;
20 struct bvec_iter iter;
21
22 if (!bio)
23 return 0;
24
25
26
27
28
29 if (bio->bi_rw & REQ_DISCARD)
30 return 1;
31
32 if (bio->bi_rw & REQ_WRITE_SAME)
33 return 1;
34
35 fbio = bio;
36 cluster = blk_queue_cluster(q);
37 seg_size = 0;
38 nr_phys_segs = 0;
39 high = 0;
40 for_each_bio(bio) {
41 bio_for_each_segment(bv, bio, iter) {
42
43
44
45
46 if (no_sg_merge)
47 goto new_segment;
48
49
50
51
52
53
54 high = page_to_pfn(bv.bv_page) > queue_bounce_pfn(q);
55 if (!high && !highprv && cluster) {
56 if (seg_size + bv.bv_len
57 > queue_max_segment_size(q))
58 goto new_segment;
59 if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv))
60 goto new_segment;
61 if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv))
62 goto new_segment;
63
64 seg_size += bv.bv_len;
65 bvprv = bv;
66 continue;
67 }
68new_segment:
69 if (nr_phys_segs == 1 && seg_size >
70 fbio->bi_seg_front_size)
71 fbio->bi_seg_front_size = seg_size;
72
73 nr_phys_segs++;
74 bvprv = bv;
75 seg_size = bv.bv_len;
76 highprv = high;
77 }
78 bbio = bio;
79 }
80
81 if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size)
82 fbio->bi_seg_front_size = seg_size;
83 if (seg_size > bbio->bi_seg_back_size)
84 bbio->bi_seg_back_size = seg_size;
85
86 return nr_phys_segs;
87}
88
89void blk_recalc_rq_segments(struct request *rq)
90{
91 bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE,
92 &rq->q->queue_flags);
93
94 rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio,
95 no_sg_merge);
96}
97
98void blk_recount_segments(struct request_queue *q, struct bio *bio)
99{
100 unsigned short seg_cnt;
101
102
103 if (bio_flagged(bio, BIO_CLONED))
104 seg_cnt = bio_segments(bio);
105 else
106 seg_cnt = bio->bi_vcnt;
107
108 if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) &&
109 (seg_cnt < queue_max_segments(q)))
110 bio->bi_phys_segments = seg_cnt;
111 else {
112 struct bio *nxt = bio->bi_next;
113
114 bio->bi_next = NULL;
115 bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false);
116 bio->bi_next = nxt;
117 }
118
119 bio->bi_flags |= (1 << BIO_SEG_VALID);
120}
121EXPORT_SYMBOL(blk_recount_segments);
122
123static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
124 struct bio *nxt)
125{
126 struct bio_vec end_bv = { NULL }, nxt_bv;
127 struct bvec_iter iter;
128
129 if (!blk_queue_cluster(q))
130 return 0;
131
132 if (bio->bi_seg_back_size + nxt->bi_seg_front_size >
133 queue_max_segment_size(q))
134 return 0;
135
136 if (!bio_has_data(bio))
137 return 1;
138
139 bio_for_each_segment(end_bv, bio, iter)
140 if (end_bv.bv_len == iter.bi_size)
141 break;
142
143 nxt_bv = bio_iovec(nxt);
144
145 if (!BIOVEC_PHYS_MERGEABLE(&end_bv, &nxt_bv))
146 return 0;
147
148
149
150
151
152 if (BIOVEC_SEG_BOUNDARY(q, &end_bv, &nxt_bv))
153 return 1;
154
155 return 0;
156}
157
158static inline void
159__blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec,
160 struct scatterlist *sglist, struct bio_vec *bvprv,
161 struct scatterlist **sg, int *nsegs, int *cluster)
162{
163
164 int nbytes = bvec->bv_len;
165
166 if (*sg && *cluster) {
167 if ((*sg)->length + nbytes > queue_max_segment_size(q))
168 goto new_segment;
169
170 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
171 goto new_segment;
172 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
173 goto new_segment;
174
175 (*sg)->length += nbytes;
176 } else {
177new_segment:
178 if (!*sg)
179 *sg = sglist;
180 else {
181
182
183
184
185
186
187
188
189
190
191 sg_unmark_end(*sg);
192 *sg = sg_next(*sg);
193 }
194
195 sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset);
196 (*nsegs)++;
197 }
198 *bvprv = *bvec;
199}
200
201static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio,
202 struct scatterlist *sglist,
203 struct scatterlist **sg)
204{
205 struct bio_vec bvec, bvprv = { NULL };
206 struct bvec_iter iter;
207 int nsegs, cluster;
208
209 nsegs = 0;
210 cluster = blk_queue_cluster(q);
211
212 if (bio->bi_rw & REQ_DISCARD) {
213
214
215
216
217
218
219
220
221 if (bio->bi_vcnt)
222 goto single_segment;
223
224 return 0;
225 }
226
227 if (bio->bi_rw & REQ_WRITE_SAME) {
228single_segment:
229 *sg = sglist;
230 bvec = bio_iovec(bio);
231 sg_set_page(*sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset);
232 return 1;
233 }
234
235 for_each_bio(bio)
236 bio_for_each_segment(bvec, bio, iter)
237 __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg,
238 &nsegs, &cluster);
239
240 return nsegs;
241}
242
243
244
245
246
247int blk_rq_map_sg(struct request_queue *q, struct request *rq,
248 struct scatterlist *sglist)
249{
250 struct scatterlist *sg = NULL;
251 int nsegs = 0;
252
253 if (rq->bio)
254 nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg);
255
256 if (unlikely(rq->cmd_flags & REQ_COPY_USER) &&
257 (blk_rq_bytes(rq) & q->dma_pad_mask)) {
258 unsigned int pad_len =
259 (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1;
260
261 sg->length += pad_len;
262 rq->extra_len += pad_len;
263 }
264
265 if (q->dma_drain_size && q->dma_drain_needed(rq)) {
266 if (rq->cmd_flags & REQ_WRITE)
267 memset(q->dma_drain_buffer, 0, q->dma_drain_size);
268
269 sg->page_link &= ~0x02;
270 sg = sg_next(sg);
271 sg_set_page(sg, virt_to_page(q->dma_drain_buffer),
272 q->dma_drain_size,
273 ((unsigned long)q->dma_drain_buffer) &
274 (PAGE_SIZE - 1));
275 nsegs++;
276 rq->extra_len += q->dma_drain_size;
277 }
278
279 if (sg)
280 sg_mark_end(sg);
281
282 return nsegs;
283}
284EXPORT_SYMBOL(blk_rq_map_sg);
285
286
287
288
289
290
291
292
293
294
295
296
297int blk_bio_map_sg(struct request_queue *q, struct bio *bio,
298 struct scatterlist *sglist)
299{
300 struct scatterlist *sg = NULL;
301 int nsegs;
302 struct bio *next = bio->bi_next;
303 bio->bi_next = NULL;
304
305 nsegs = __blk_bios_map_sg(q, bio, sglist, &sg);
306 bio->bi_next = next;
307 if (sg)
308 sg_mark_end(sg);
309
310 BUG_ON(bio->bi_phys_segments && nsegs > bio->bi_phys_segments);
311 return nsegs;
312}
313EXPORT_SYMBOL(blk_bio_map_sg);
314
315static inline int ll_new_hw_segment(struct request_queue *q,
316 struct request *req,
317 struct bio *bio)
318{
319 int nr_phys_segs = bio_phys_segments(q, bio);
320
321 if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q))
322 goto no_merge;
323
324 if (blk_integrity_merge_bio(q, req, bio) == false)
325 goto no_merge;
326
327
328
329
330
331 req->nr_phys_segments += nr_phys_segs;
332 return 1;
333
334no_merge:
335 req->cmd_flags |= REQ_NOMERGE;
336 if (req == q->last_merge)
337 q->last_merge = NULL;
338 return 0;
339}
340
341int ll_back_merge_fn(struct request_queue *q, struct request *req,
342 struct bio *bio)
343{
344 if (blk_rq_sectors(req) + bio_sectors(bio) >
345 blk_rq_get_max_sectors(req)) {
346 req->cmd_flags |= REQ_NOMERGE;
347 if (req == q->last_merge)
348 q->last_merge = NULL;
349 return 0;
350 }
351 if (!bio_flagged(req->biotail, BIO_SEG_VALID))
352 blk_recount_segments(q, req->biotail);
353 if (!bio_flagged(bio, BIO_SEG_VALID))
354 blk_recount_segments(q, bio);
355
356 return ll_new_hw_segment(q, req, bio);
357}
358
359int ll_front_merge_fn(struct request_queue *q, struct request *req,
360 struct bio *bio)
361{
362 if (blk_rq_sectors(req) + bio_sectors(bio) >
363 blk_rq_get_max_sectors(req)) {
364 req->cmd_flags |= REQ_NOMERGE;
365 if (req == q->last_merge)
366 q->last_merge = NULL;
367 return 0;
368 }
369 if (!bio_flagged(bio, BIO_SEG_VALID))
370 blk_recount_segments(q, bio);
371 if (!bio_flagged(req->bio, BIO_SEG_VALID))
372 blk_recount_segments(q, req->bio);
373
374 return ll_new_hw_segment(q, req, bio);
375}
376
377
378
379
380
381static bool req_no_special_merge(struct request *req)
382{
383 struct request_queue *q = req->q;
384
385 return !q->mq_ops && req->special;
386}
387
388static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
389 struct request *next)
390{
391 int total_phys_segments;
392 unsigned int seg_size =
393 req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size;
394
395
396
397
398
399 if (req_no_special_merge(req) || req_no_special_merge(next))
400 return 0;
401
402
403
404
405 if ((blk_rq_sectors(req) + blk_rq_sectors(next)) >
406 blk_rq_get_max_sectors(req))
407 return 0;
408
409 total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
410 if (blk_phys_contig_segment(q, req->biotail, next->bio)) {
411 if (req->nr_phys_segments == 1)
412 req->bio->bi_seg_front_size = seg_size;
413 if (next->nr_phys_segments == 1)
414 next->biotail->bi_seg_back_size = seg_size;
415 total_phys_segments--;
416 }
417
418 if (total_phys_segments > queue_max_segments(q))
419 return 0;
420
421 if (blk_integrity_merge_rq(q, req, next) == false)
422 return 0;
423
424
425 req->nr_phys_segments = total_phys_segments;
426 return 1;
427}
428
429
430
431
432
433
434
435
436
437
438void blk_rq_set_mixed_merge(struct request *rq)
439{
440 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
441 struct bio *bio;
442
443 if (rq->cmd_flags & REQ_MIXED_MERGE)
444 return;
445
446
447
448
449
450
451 for (bio = rq->bio; bio; bio = bio->bi_next) {
452 WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) &&
453 (bio->bi_rw & REQ_FAILFAST_MASK) != ff);
454 bio->bi_rw |= ff;
455 }
456 rq->cmd_flags |= REQ_MIXED_MERGE;
457}
458
459static void blk_account_io_merge(struct request *req)
460{
461 if (blk_do_io_stat(req)) {
462 struct hd_struct *part;
463 int cpu;
464
465 cpu = part_stat_lock();
466 part = req->part;
467
468 part_round_stats(cpu, part);
469 part_dec_in_flight(part, rq_data_dir(req));
470
471 hd_struct_put(part);
472 part_stat_unlock();
473 }
474}
475
476
477
478
479static int attempt_merge(struct request_queue *q, struct request *req,
480 struct request *next)
481{
482 if (!rq_mergeable(req) || !rq_mergeable(next))
483 return 0;
484
485 if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags))
486 return 0;
487
488
489
490
491 if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next))
492 return 0;
493
494 if (rq_data_dir(req) != rq_data_dir(next)
495 || req->rq_disk != next->rq_disk
496 || req_no_special_merge(next))
497 return 0;
498
499 if (req->cmd_flags & REQ_WRITE_SAME &&
500 !blk_write_same_mergeable(req->bio, next->bio))
501 return 0;
502
503
504
505
506
507
508
509 if (!ll_merge_requests_fn(q, req, next))
510 return 0;
511
512
513
514
515
516
517
518 if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE ||
519 (req->cmd_flags & REQ_FAILFAST_MASK) !=
520 (next->cmd_flags & REQ_FAILFAST_MASK)) {
521 blk_rq_set_mixed_merge(req);
522 blk_rq_set_mixed_merge(next);
523 }
524
525
526
527
528
529
530
531 if (time_after(req->start_time, next->start_time))
532 req->start_time = next->start_time;
533
534 req->biotail->bi_next = next->bio;
535 req->biotail = next->biotail;
536
537 req->__data_len += blk_rq_bytes(next);
538
539 elv_merge_requests(q, req, next);
540
541
542
543
544 blk_account_io_merge(next);
545
546 req->ioprio = ioprio_best(req->ioprio, next->ioprio);
547 if (blk_rq_cpu_valid(next))
548 req->cpu = next->cpu;
549
550
551 next->bio = NULL;
552 __blk_put_request(q, next);
553 return 1;
554}
555
556int attempt_back_merge(struct request_queue *q, struct request *rq)
557{
558 struct request *next = elv_latter_request(q, rq);
559
560 if (next)
561 return attempt_merge(q, rq, next);
562
563 return 0;
564}
565
566int attempt_front_merge(struct request_queue *q, struct request *rq)
567{
568 struct request *prev = elv_former_request(q, rq);
569
570 if (prev)
571 return attempt_merge(q, prev, rq);
572
573 return 0;
574}
575
576int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
577 struct request *next)
578{
579 return attempt_merge(q, rq, next);
580}
581
582bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
583{
584 struct request_queue *q = rq->q;
585
586 if (!rq_mergeable(rq) || !bio_mergeable(bio))
587 return false;
588
589 if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw))
590 return false;
591
592
593 if (bio_data_dir(bio) != rq_data_dir(rq))
594 return false;
595
596
597 if (rq->rq_disk != bio->bi_bdev->bd_disk || req_no_special_merge(rq))
598 return false;
599
600
601 if (blk_integrity_merge_bio(rq->q, rq, bio) == false)
602 return false;
603
604
605 if (rq->cmd_flags & REQ_WRITE_SAME &&
606 !blk_write_same_mergeable(rq->bio, bio))
607 return false;
608
609 if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS)) {
610 struct bio_vec *bprev;
611
612 bprev = &rq->biotail->bi_io_vec[bio->bi_vcnt - 1];
613 if (bvec_gap_to_prev(bprev, bio->bi_io_vec[0].bv_offset))
614 return false;
615 }
616
617 return true;
618}
619
620int blk_try_merge(struct request *rq, struct bio *bio)
621{
622 if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
623 return ELEVATOR_BACK_MERGE;
624 else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector)
625 return ELEVATOR_FRONT_MERGE;
626 return ELEVATOR_NO_MERGE;
627}
628