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