]>
Commit | Line | Data |
---|---|---|
d6d48196 JA |
1 | /* |
2 | * Functions related to segment and merge handling | |
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 | ||
54efd50b KO |
12 | static struct bio *blk_bio_discard_split(struct request_queue *q, |
13 | struct bio *bio, | |
bdced438 ML |
14 | struct bio_set *bs, |
15 | unsigned *nsegs) | |
54efd50b KO |
16 | { |
17 | unsigned int max_discard_sectors, granularity; | |
18 | int alignment; | |
19 | sector_t tmp; | |
20 | unsigned split_sectors; | |
21 | ||
bdced438 ML |
22 | *nsegs = 1; |
23 | ||
54efd50b KO |
24 | /* Zero-sector (unknown) and one-sector granularities are the same. */ |
25 | granularity = max(q->limits.discard_granularity >> 9, 1U); | |
26 | ||
27 | max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); | |
28 | max_discard_sectors -= max_discard_sectors % granularity; | |
29 | ||
30 | if (unlikely(!max_discard_sectors)) { | |
31 | /* XXX: warn */ | |
32 | return NULL; | |
33 | } | |
34 | ||
35 | if (bio_sectors(bio) <= max_discard_sectors) | |
36 | return NULL; | |
37 | ||
38 | split_sectors = max_discard_sectors; | |
39 | ||
40 | /* | |
41 | * If the next starting sector would be misaligned, stop the discard at | |
42 | * the previous aligned sector. | |
43 | */ | |
44 | alignment = (q->limits.discard_alignment >> 9) % granularity; | |
45 | ||
46 | tmp = bio->bi_iter.bi_sector + split_sectors - alignment; | |
47 | tmp = sector_div(tmp, granularity); | |
48 | ||
49 | if (split_sectors > tmp) | |
50 | split_sectors -= tmp; | |
51 | ||
52 | return bio_split(bio, split_sectors, GFP_NOIO, bs); | |
53 | } | |
54 | ||
55 | static struct bio *blk_bio_write_same_split(struct request_queue *q, | |
56 | struct bio *bio, | |
bdced438 ML |
57 | struct bio_set *bs, |
58 | unsigned *nsegs) | |
54efd50b | 59 | { |
bdced438 ML |
60 | *nsegs = 1; |
61 | ||
54efd50b KO |
62 | if (!q->limits.max_write_same_sectors) |
63 | return NULL; | |
64 | ||
65 | if (bio_sectors(bio) <= q->limits.max_write_same_sectors) | |
66 | return NULL; | |
67 | ||
68 | return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); | |
69 | } | |
70 | ||
71 | static struct bio *blk_bio_segment_split(struct request_queue *q, | |
72 | struct bio *bio, | |
bdced438 ML |
73 | struct bio_set *bs, |
74 | unsigned *segs) | |
54efd50b | 75 | { |
5014c311 | 76 | struct bio_vec bv, bvprv, *bvprvp = NULL; |
54efd50b | 77 | struct bvec_iter iter; |
8ae12666 | 78 | unsigned seg_size = 0, nsegs = 0, sectors = 0; |
54efd50b | 79 | |
54efd50b | 80 | bio_for_each_segment(bv, bio, iter) { |
52cc6eea | 81 | if (sectors + (bv.bv_len >> 9) > queue_max_sectors(q)) |
54efd50b KO |
82 | goto split; |
83 | ||
84 | /* | |
85 | * If the queue doesn't support SG gaps and adding this | |
86 | * offset would create a gap, disallow it. | |
87 | */ | |
5014c311 | 88 | if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) |
54efd50b KO |
89 | goto split; |
90 | ||
5014c311 | 91 | if (bvprvp && blk_queue_cluster(q)) { |
54efd50b KO |
92 | if (seg_size + bv.bv_len > queue_max_segment_size(q)) |
93 | goto new_segment; | |
5014c311 | 94 | if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv)) |
54efd50b | 95 | goto new_segment; |
5014c311 | 96 | if (!BIOVEC_SEG_BOUNDARY(q, bvprvp, &bv)) |
54efd50b KO |
97 | goto new_segment; |
98 | ||
99 | seg_size += bv.bv_len; | |
100 | bvprv = bv; | |
5014c311 | 101 | bvprvp = &bv; |
52cc6eea | 102 | sectors += bv.bv_len >> 9; |
54efd50b KO |
103 | continue; |
104 | } | |
105 | new_segment: | |
106 | if (nsegs == queue_max_segments(q)) | |
107 | goto split; | |
108 | ||
109 | nsegs++; | |
110 | bvprv = bv; | |
5014c311 | 111 | bvprvp = &bv; |
54efd50b | 112 | seg_size = bv.bv_len; |
52cc6eea | 113 | sectors += bv.bv_len >> 9; |
54efd50b KO |
114 | } |
115 | ||
bdced438 | 116 | *segs = nsegs; |
54efd50b KO |
117 | return NULL; |
118 | split: | |
bdced438 | 119 | *segs = nsegs; |
52cc6eea | 120 | return bio_split(bio, sectors, GFP_NOIO, bs); |
54efd50b KO |
121 | } |
122 | ||
123 | void blk_queue_split(struct request_queue *q, struct bio **bio, | |
124 | struct bio_set *bs) | |
125 | { | |
bdced438 ML |
126 | struct bio *split, *res; |
127 | unsigned nsegs; | |
54efd50b KO |
128 | |
129 | if ((*bio)->bi_rw & REQ_DISCARD) | |
bdced438 | 130 | split = blk_bio_discard_split(q, *bio, bs, &nsegs); |
54efd50b | 131 | else if ((*bio)->bi_rw & REQ_WRITE_SAME) |
bdced438 | 132 | split = blk_bio_write_same_split(q, *bio, bs, &nsegs); |
54efd50b | 133 | else |
bdced438 ML |
134 | split = blk_bio_segment_split(q, *bio, q->bio_split, &nsegs); |
135 | ||
136 | /* physical segments can be figured out during splitting */ | |
137 | res = split ? split : *bio; | |
138 | res->bi_phys_segments = nsegs; | |
139 | bio_set_flag(res, BIO_SEG_VALID); | |
54efd50b KO |
140 | |
141 | if (split) { | |
142 | bio_chain(split, *bio); | |
143 | generic_make_request(*bio); | |
144 | *bio = split; | |
145 | } | |
146 | } | |
147 | EXPORT_SYMBOL(blk_queue_split); | |
148 | ||
1e428079 | 149 | static unsigned int __blk_recalc_rq_segments(struct request_queue *q, |
07388549 ML |
150 | struct bio *bio, |
151 | bool no_sg_merge) | |
d6d48196 | 152 | { |
7988613b | 153 | struct bio_vec bv, bvprv = { NULL }; |
54efd50b | 154 | int cluster, prev = 0; |
1e428079 | 155 | unsigned int seg_size, nr_phys_segs; |
59247eae | 156 | struct bio *fbio, *bbio; |
7988613b | 157 | struct bvec_iter iter; |
d6d48196 | 158 | |
1e428079 JA |
159 | if (!bio) |
160 | return 0; | |
d6d48196 | 161 | |
5cb8850c KO |
162 | /* |
163 | * This should probably be returning 0, but blk_add_request_payload() | |
164 | * (Christoph!!!!) | |
165 | */ | |
166 | if (bio->bi_rw & REQ_DISCARD) | |
167 | return 1; | |
168 | ||
169 | if (bio->bi_rw & REQ_WRITE_SAME) | |
170 | return 1; | |
171 | ||
1e428079 | 172 | fbio = bio; |
e692cb66 | 173 | cluster = blk_queue_cluster(q); |
5df97b91 | 174 | seg_size = 0; |
2c8919de | 175 | nr_phys_segs = 0; |
1e428079 | 176 | for_each_bio(bio) { |
7988613b | 177 | bio_for_each_segment(bv, bio, iter) { |
05f1dd53 JA |
178 | /* |
179 | * If SG merging is disabled, each bio vector is | |
180 | * a segment | |
181 | */ | |
182 | if (no_sg_merge) | |
183 | goto new_segment; | |
184 | ||
54efd50b | 185 | if (prev && cluster) { |
7988613b | 186 | if (seg_size + bv.bv_len |
ae03bf63 | 187 | > queue_max_segment_size(q)) |
1e428079 | 188 | goto new_segment; |
7988613b | 189 | if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv)) |
1e428079 | 190 | goto new_segment; |
7988613b | 191 | if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv)) |
1e428079 | 192 | goto new_segment; |
d6d48196 | 193 | |
7988613b | 194 | seg_size += bv.bv_len; |
1e428079 JA |
195 | bvprv = bv; |
196 | continue; | |
197 | } | |
d6d48196 | 198 | new_segment: |
1e428079 JA |
199 | if (nr_phys_segs == 1 && seg_size > |
200 | fbio->bi_seg_front_size) | |
201 | fbio->bi_seg_front_size = seg_size; | |
86771427 | 202 | |
1e428079 JA |
203 | nr_phys_segs++; |
204 | bvprv = bv; | |
54efd50b | 205 | prev = 1; |
7988613b | 206 | seg_size = bv.bv_len; |
1e428079 | 207 | } |
59247eae | 208 | bbio = bio; |
d6d48196 JA |
209 | } |
210 | ||
59247eae JA |
211 | if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) |
212 | fbio->bi_seg_front_size = seg_size; | |
213 | if (seg_size > bbio->bi_seg_back_size) | |
214 | bbio->bi_seg_back_size = seg_size; | |
1e428079 JA |
215 | |
216 | return nr_phys_segs; | |
217 | } | |
218 | ||
219 | void blk_recalc_rq_segments(struct request *rq) | |
220 | { | |
07388549 ML |
221 | bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, |
222 | &rq->q->queue_flags); | |
223 | ||
224 | rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio, | |
225 | no_sg_merge); | |
d6d48196 JA |
226 | } |
227 | ||
228 | void blk_recount_segments(struct request_queue *q, struct bio *bio) | |
229 | { | |
7f60dcaa ML |
230 | unsigned short seg_cnt; |
231 | ||
232 | /* estimate segment number by bi_vcnt for non-cloned bio */ | |
233 | if (bio_flagged(bio, BIO_CLONED)) | |
234 | seg_cnt = bio_segments(bio); | |
235 | else | |
236 | seg_cnt = bio->bi_vcnt; | |
764f612c | 237 | |
7f60dcaa ML |
238 | if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) && |
239 | (seg_cnt < queue_max_segments(q))) | |
240 | bio->bi_phys_segments = seg_cnt; | |
05f1dd53 JA |
241 | else { |
242 | struct bio *nxt = bio->bi_next; | |
243 | ||
244 | bio->bi_next = NULL; | |
7f60dcaa | 245 | bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false); |
05f1dd53 JA |
246 | bio->bi_next = nxt; |
247 | } | |
1e428079 | 248 | |
b7c44ed9 | 249 | bio_set_flag(bio, BIO_SEG_VALID); |
d6d48196 JA |
250 | } |
251 | EXPORT_SYMBOL(blk_recount_segments); | |
252 | ||
253 | static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, | |
254 | struct bio *nxt) | |
255 | { | |
2b8221e1 | 256 | struct bio_vec end_bv = { NULL }, nxt_bv; |
f619d254 KO |
257 | struct bvec_iter iter; |
258 | ||
e692cb66 | 259 | if (!blk_queue_cluster(q)) |
d6d48196 JA |
260 | return 0; |
261 | ||
86771427 | 262 | if (bio->bi_seg_back_size + nxt->bi_seg_front_size > |
ae03bf63 | 263 | queue_max_segment_size(q)) |
d6d48196 JA |
264 | return 0; |
265 | ||
e17fc0a1 DW |
266 | if (!bio_has_data(bio)) |
267 | return 1; | |
268 | ||
f619d254 KO |
269 | bio_for_each_segment(end_bv, bio, iter) |
270 | if (end_bv.bv_len == iter.bi_size) | |
271 | break; | |
272 | ||
273 | nxt_bv = bio_iovec(nxt); | |
274 | ||
275 | if (!BIOVEC_PHYS_MERGEABLE(&end_bv, &nxt_bv)) | |
e17fc0a1 DW |
276 | return 0; |
277 | ||
d6d48196 | 278 | /* |
e17fc0a1 | 279 | * bio and nxt are contiguous in memory; check if the queue allows |
d6d48196 JA |
280 | * these two to be merged into one |
281 | */ | |
f619d254 | 282 | if (BIOVEC_SEG_BOUNDARY(q, &end_bv, &nxt_bv)) |
d6d48196 JA |
283 | return 1; |
284 | ||
285 | return 0; | |
286 | } | |
287 | ||
7988613b | 288 | static inline void |
963ab9e5 | 289 | __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, |
7988613b | 290 | struct scatterlist *sglist, struct bio_vec *bvprv, |
963ab9e5 AH |
291 | struct scatterlist **sg, int *nsegs, int *cluster) |
292 | { | |
293 | ||
294 | int nbytes = bvec->bv_len; | |
295 | ||
7988613b | 296 | if (*sg && *cluster) { |
963ab9e5 AH |
297 | if ((*sg)->length + nbytes > queue_max_segment_size(q)) |
298 | goto new_segment; | |
299 | ||
7988613b | 300 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) |
963ab9e5 | 301 | goto new_segment; |
7988613b | 302 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) |
963ab9e5 AH |
303 | goto new_segment; |
304 | ||
305 | (*sg)->length += nbytes; | |
306 | } else { | |
307 | new_segment: | |
308 | if (!*sg) | |
309 | *sg = sglist; | |
310 | else { | |
311 | /* | |
312 | * If the driver previously mapped a shorter | |
313 | * list, we could see a termination bit | |
314 | * prematurely unless it fully inits the sg | |
315 | * table on each mapping. We KNOW that there | |
316 | * must be more entries here or the driver | |
317 | * would be buggy, so force clear the | |
318 | * termination bit to avoid doing a full | |
319 | * sg_init_table() in drivers for each command. | |
320 | */ | |
c8164d89 | 321 | sg_unmark_end(*sg); |
963ab9e5 AH |
322 | *sg = sg_next(*sg); |
323 | } | |
324 | ||
325 | sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); | |
326 | (*nsegs)++; | |
327 | } | |
7988613b | 328 | *bvprv = *bvec; |
963ab9e5 AH |
329 | } |
330 | ||
5cb8850c KO |
331 | static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, |
332 | struct scatterlist *sglist, | |
333 | struct scatterlist **sg) | |
d6d48196 | 334 | { |
2b8221e1 | 335 | struct bio_vec bvec, bvprv = { NULL }; |
5cb8850c | 336 | struct bvec_iter iter; |
d6d48196 JA |
337 | int nsegs, cluster; |
338 | ||
339 | nsegs = 0; | |
e692cb66 | 340 | cluster = blk_queue_cluster(q); |
d6d48196 | 341 | |
5cb8850c KO |
342 | if (bio->bi_rw & REQ_DISCARD) { |
343 | /* | |
344 | * This is a hack - drivers should be neither modifying the | |
345 | * biovec, nor relying on bi_vcnt - but because of | |
346 | * blk_add_request_payload(), a discard bio may or may not have | |
347 | * a payload we need to set up here (thank you Christoph) and | |
348 | * bi_vcnt is really the only way of telling if we need to. | |
349 | */ | |
350 | ||
351 | if (bio->bi_vcnt) | |
352 | goto single_segment; | |
353 | ||
354 | return 0; | |
355 | } | |
356 | ||
357 | if (bio->bi_rw & REQ_WRITE_SAME) { | |
358 | single_segment: | |
359 | *sg = sglist; | |
360 | bvec = bio_iovec(bio); | |
361 | sg_set_page(*sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset); | |
362 | return 1; | |
363 | } | |
364 | ||
365 | for_each_bio(bio) | |
366 | bio_for_each_segment(bvec, bio, iter) | |
367 | __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, | |
368 | &nsegs, &cluster); | |
d6d48196 | 369 | |
5cb8850c KO |
370 | return nsegs; |
371 | } | |
372 | ||
373 | /* | |
374 | * map a request to scatterlist, return number of sg entries setup. Caller | |
375 | * must make sure sg can hold rq->nr_phys_segments entries | |
376 | */ | |
377 | int blk_rq_map_sg(struct request_queue *q, struct request *rq, | |
378 | struct scatterlist *sglist) | |
379 | { | |
380 | struct scatterlist *sg = NULL; | |
381 | int nsegs = 0; | |
382 | ||
383 | if (rq->bio) | |
384 | nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); | |
f18573ab FT |
385 | |
386 | if (unlikely(rq->cmd_flags & REQ_COPY_USER) && | |
2e46e8b2 TH |
387 | (blk_rq_bytes(rq) & q->dma_pad_mask)) { |
388 | unsigned int pad_len = | |
389 | (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; | |
f18573ab FT |
390 | |
391 | sg->length += pad_len; | |
392 | rq->extra_len += pad_len; | |
393 | } | |
394 | ||
2fb98e84 | 395 | if (q->dma_drain_size && q->dma_drain_needed(rq)) { |
7b6d91da | 396 | if (rq->cmd_flags & REQ_WRITE) |
db0a2e00 TH |
397 | memset(q->dma_drain_buffer, 0, q->dma_drain_size); |
398 | ||
da81ed16 | 399 | sg_unmark_end(sg); |
d6d48196 JA |
400 | sg = sg_next(sg); |
401 | sg_set_page(sg, virt_to_page(q->dma_drain_buffer), | |
402 | q->dma_drain_size, | |
403 | ((unsigned long)q->dma_drain_buffer) & | |
404 | (PAGE_SIZE - 1)); | |
405 | nsegs++; | |
7a85f889 | 406 | rq->extra_len += q->dma_drain_size; |
d6d48196 JA |
407 | } |
408 | ||
409 | if (sg) | |
410 | sg_mark_end(sg); | |
411 | ||
412 | return nsegs; | |
413 | } | |
d6d48196 JA |
414 | EXPORT_SYMBOL(blk_rq_map_sg); |
415 | ||
d6d48196 JA |
416 | static inline int ll_new_hw_segment(struct request_queue *q, |
417 | struct request *req, | |
418 | struct bio *bio) | |
419 | { | |
d6d48196 JA |
420 | int nr_phys_segs = bio_phys_segments(q, bio); |
421 | ||
13f05c8d MP |
422 | if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) |
423 | goto no_merge; | |
424 | ||
4eaf99be | 425 | if (blk_integrity_merge_bio(q, req, bio) == false) |
13f05c8d | 426 | goto no_merge; |
d6d48196 JA |
427 | |
428 | /* | |
429 | * This will form the start of a new hw segment. Bump both | |
430 | * counters. | |
431 | */ | |
d6d48196 JA |
432 | req->nr_phys_segments += nr_phys_segs; |
433 | return 1; | |
13f05c8d MP |
434 | |
435 | no_merge: | |
436 | req->cmd_flags |= REQ_NOMERGE; | |
437 | if (req == q->last_merge) | |
438 | q->last_merge = NULL; | |
439 | return 0; | |
d6d48196 JA |
440 | } |
441 | ||
442 | int ll_back_merge_fn(struct request_queue *q, struct request *req, | |
443 | struct bio *bio) | |
444 | { | |
5e7c4274 JA |
445 | if (req_gap_back_merge(req, bio)) |
446 | return 0; | |
7f39add3 SG |
447 | if (blk_integrity_rq(req) && |
448 | integrity_req_gap_back_merge(req, bio)) | |
449 | return 0; | |
f31dc1cd MP |
450 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
451 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
452 | req->cmd_flags |= REQ_NOMERGE; |
453 | if (req == q->last_merge) | |
454 | q->last_merge = NULL; | |
455 | return 0; | |
456 | } | |
2cdf79ca | 457 | if (!bio_flagged(req->biotail, BIO_SEG_VALID)) |
d6d48196 | 458 | blk_recount_segments(q, req->biotail); |
2cdf79ca | 459 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 460 | blk_recount_segments(q, bio); |
d6d48196 JA |
461 | |
462 | return ll_new_hw_segment(q, req, bio); | |
463 | } | |
464 | ||
6728cb0e | 465 | int ll_front_merge_fn(struct request_queue *q, struct request *req, |
d6d48196 JA |
466 | struct bio *bio) |
467 | { | |
5e7c4274 JA |
468 | |
469 | if (req_gap_front_merge(req, bio)) | |
470 | return 0; | |
7f39add3 SG |
471 | if (blk_integrity_rq(req) && |
472 | integrity_req_gap_front_merge(req, bio)) | |
473 | return 0; | |
f31dc1cd MP |
474 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
475 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
476 | req->cmd_flags |= REQ_NOMERGE; |
477 | if (req == q->last_merge) | |
478 | q->last_merge = NULL; | |
479 | return 0; | |
480 | } | |
2cdf79ca | 481 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 482 | blk_recount_segments(q, bio); |
2cdf79ca | 483 | if (!bio_flagged(req->bio, BIO_SEG_VALID)) |
d6d48196 | 484 | blk_recount_segments(q, req->bio); |
d6d48196 JA |
485 | |
486 | return ll_new_hw_segment(q, req, bio); | |
487 | } | |
488 | ||
e7e24500 JA |
489 | /* |
490 | * blk-mq uses req->special to carry normal driver per-request payload, it | |
491 | * does not indicate a prepared command that we cannot merge with. | |
492 | */ | |
493 | static bool req_no_special_merge(struct request *req) | |
494 | { | |
495 | struct request_queue *q = req->q; | |
496 | ||
497 | return !q->mq_ops && req->special; | |
498 | } | |
499 | ||
d6d48196 JA |
500 | static int ll_merge_requests_fn(struct request_queue *q, struct request *req, |
501 | struct request *next) | |
502 | { | |
503 | int total_phys_segments; | |
86771427 FT |
504 | unsigned int seg_size = |
505 | req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; | |
d6d48196 JA |
506 | |
507 | /* | |
508 | * First check if the either of the requests are re-queued | |
509 | * requests. Can't merge them if they are. | |
510 | */ | |
e7e24500 | 511 | if (req_no_special_merge(req) || req_no_special_merge(next)) |
d6d48196 JA |
512 | return 0; |
513 | ||
5e7c4274 | 514 | if (req_gap_back_merge(req, next->bio)) |
854fbb9c KB |
515 | return 0; |
516 | ||
d6d48196 JA |
517 | /* |
518 | * Will it become too large? | |
519 | */ | |
f31dc1cd MP |
520 | if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > |
521 | blk_rq_get_max_sectors(req)) | |
d6d48196 JA |
522 | return 0; |
523 | ||
524 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
86771427 FT |
525 | if (blk_phys_contig_segment(q, req->biotail, next->bio)) { |
526 | if (req->nr_phys_segments == 1) | |
527 | req->bio->bi_seg_front_size = seg_size; | |
528 | if (next->nr_phys_segments == 1) | |
529 | next->biotail->bi_seg_back_size = seg_size; | |
d6d48196 | 530 | total_phys_segments--; |
86771427 | 531 | } |
d6d48196 | 532 | |
8a78362c | 533 | if (total_phys_segments > queue_max_segments(q)) |
d6d48196 JA |
534 | return 0; |
535 | ||
4eaf99be | 536 | if (blk_integrity_merge_rq(q, req, next) == false) |
13f05c8d MP |
537 | return 0; |
538 | ||
d6d48196 JA |
539 | /* Merge is OK... */ |
540 | req->nr_phys_segments = total_phys_segments; | |
d6d48196 JA |
541 | return 1; |
542 | } | |
543 | ||
80a761fd TH |
544 | /** |
545 | * blk_rq_set_mixed_merge - mark a request as mixed merge | |
546 | * @rq: request to mark as mixed merge | |
547 | * | |
548 | * Description: | |
549 | * @rq is about to be mixed merged. Make sure the attributes | |
550 | * which can be mixed are set in each bio and mark @rq as mixed | |
551 | * merged. | |
552 | */ | |
553 | void blk_rq_set_mixed_merge(struct request *rq) | |
554 | { | |
555 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
556 | struct bio *bio; | |
557 | ||
558 | if (rq->cmd_flags & REQ_MIXED_MERGE) | |
559 | return; | |
560 | ||
561 | /* | |
562 | * @rq will no longer represent mixable attributes for all the | |
563 | * contained bios. It will just track those of the first one. | |
564 | * Distributes the attributs to each bio. | |
565 | */ | |
566 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
567 | WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) && | |
568 | (bio->bi_rw & REQ_FAILFAST_MASK) != ff); | |
569 | bio->bi_rw |= ff; | |
570 | } | |
571 | rq->cmd_flags |= REQ_MIXED_MERGE; | |
572 | } | |
573 | ||
26308eab JM |
574 | static void blk_account_io_merge(struct request *req) |
575 | { | |
576 | if (blk_do_io_stat(req)) { | |
577 | struct hd_struct *part; | |
578 | int cpu; | |
579 | ||
580 | cpu = part_stat_lock(); | |
09e099d4 | 581 | part = req->part; |
26308eab JM |
582 | |
583 | part_round_stats(cpu, part); | |
316d315b | 584 | part_dec_in_flight(part, rq_data_dir(req)); |
26308eab | 585 | |
6c23a968 | 586 | hd_struct_put(part); |
26308eab JM |
587 | part_stat_unlock(); |
588 | } | |
589 | } | |
590 | ||
d6d48196 JA |
591 | /* |
592 | * Has to be called with the request spinlock acquired | |
593 | */ | |
594 | static int attempt_merge(struct request_queue *q, struct request *req, | |
595 | struct request *next) | |
596 | { | |
597 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
598 | return 0; | |
599 | ||
f31dc1cd MP |
600 | if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags)) |
601 | return 0; | |
602 | ||
d6d48196 JA |
603 | /* |
604 | * not contiguous | |
605 | */ | |
83096ebf | 606 | if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next)) |
d6d48196 JA |
607 | return 0; |
608 | ||
609 | if (rq_data_dir(req) != rq_data_dir(next) | |
610 | || req->rq_disk != next->rq_disk | |
e7e24500 | 611 | || req_no_special_merge(next)) |
d6d48196 JA |
612 | return 0; |
613 | ||
4363ac7c MP |
614 | if (req->cmd_flags & REQ_WRITE_SAME && |
615 | !blk_write_same_mergeable(req->bio, next->bio)) | |
616 | return 0; | |
617 | ||
d6d48196 JA |
618 | /* |
619 | * If we are allowed to merge, then append bio list | |
620 | * from next to rq and release next. merge_requests_fn | |
621 | * will have updated segment counts, update sector | |
622 | * counts here. | |
623 | */ | |
624 | if (!ll_merge_requests_fn(q, req, next)) | |
625 | return 0; | |
626 | ||
80a761fd TH |
627 | /* |
628 | * If failfast settings disagree or any of the two is already | |
629 | * a mixed merge, mark both as mixed before proceeding. This | |
630 | * makes sure that all involved bios have mixable attributes | |
631 | * set properly. | |
632 | */ | |
633 | if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE || | |
634 | (req->cmd_flags & REQ_FAILFAST_MASK) != | |
635 | (next->cmd_flags & REQ_FAILFAST_MASK)) { | |
636 | blk_rq_set_mixed_merge(req); | |
637 | blk_rq_set_mixed_merge(next); | |
638 | } | |
639 | ||
d6d48196 JA |
640 | /* |
641 | * At this point we have either done a back merge | |
642 | * or front merge. We need the smaller start_time of | |
643 | * the merged requests to be the current request | |
644 | * for accounting purposes. | |
645 | */ | |
646 | if (time_after(req->start_time, next->start_time)) | |
647 | req->start_time = next->start_time; | |
648 | ||
649 | req->biotail->bi_next = next->bio; | |
650 | req->biotail = next->biotail; | |
651 | ||
a2dec7b3 | 652 | req->__data_len += blk_rq_bytes(next); |
d6d48196 JA |
653 | |
654 | elv_merge_requests(q, req, next); | |
655 | ||
42dad764 JM |
656 | /* |
657 | * 'next' is going away, so update stats accordingly | |
658 | */ | |
659 | blk_account_io_merge(next); | |
d6d48196 JA |
660 | |
661 | req->ioprio = ioprio_best(req->ioprio, next->ioprio); | |
ab780f1e JA |
662 | if (blk_rq_cpu_valid(next)) |
663 | req->cpu = next->cpu; | |
d6d48196 | 664 | |
1cd96c24 BH |
665 | /* owner-ship of bio passed from next to req */ |
666 | next->bio = NULL; | |
d6d48196 JA |
667 | __blk_put_request(q, next); |
668 | return 1; | |
669 | } | |
670 | ||
671 | int attempt_back_merge(struct request_queue *q, struct request *rq) | |
672 | { | |
673 | struct request *next = elv_latter_request(q, rq); | |
674 | ||
675 | if (next) | |
676 | return attempt_merge(q, rq, next); | |
677 | ||
678 | return 0; | |
679 | } | |
680 | ||
681 | int attempt_front_merge(struct request_queue *q, struct request *rq) | |
682 | { | |
683 | struct request *prev = elv_former_request(q, rq); | |
684 | ||
685 | if (prev) | |
686 | return attempt_merge(q, prev, rq); | |
687 | ||
688 | return 0; | |
689 | } | |
5e84ea3a JA |
690 | |
691 | int blk_attempt_req_merge(struct request_queue *q, struct request *rq, | |
692 | struct request *next) | |
693 | { | |
694 | return attempt_merge(q, rq, next); | |
695 | } | |
050c8ea8 TH |
696 | |
697 | bool blk_rq_merge_ok(struct request *rq, struct bio *bio) | |
698 | { | |
e2a60da7 | 699 | if (!rq_mergeable(rq) || !bio_mergeable(bio)) |
050c8ea8 TH |
700 | return false; |
701 | ||
f31dc1cd MP |
702 | if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw)) |
703 | return false; | |
704 | ||
050c8ea8 TH |
705 | /* different data direction or already started, don't merge */ |
706 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
707 | return false; | |
708 | ||
709 | /* must be same device and not a special request */ | |
e7e24500 | 710 | if (rq->rq_disk != bio->bi_bdev->bd_disk || req_no_special_merge(rq)) |
050c8ea8 TH |
711 | return false; |
712 | ||
713 | /* only merge integrity protected bio into ditto rq */ | |
4eaf99be | 714 | if (blk_integrity_merge_bio(rq->q, rq, bio) == false) |
050c8ea8 TH |
715 | return false; |
716 | ||
4363ac7c MP |
717 | /* must be using the same buffer */ |
718 | if (rq->cmd_flags & REQ_WRITE_SAME && | |
719 | !blk_write_same_mergeable(rq->bio, bio)) | |
720 | return false; | |
721 | ||
050c8ea8 TH |
722 | return true; |
723 | } | |
724 | ||
725 | int blk_try_merge(struct request *rq, struct bio *bio) | |
726 | { | |
4f024f37 | 727 | if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) |
050c8ea8 | 728 | return ELEVATOR_BACK_MERGE; |
4f024f37 | 729 | else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) |
050c8ea8 TH |
730 | return ELEVATOR_FRONT_MERGE; |
731 | return ELEVATOR_NO_MERGE; | |
732 | } |