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; |
02e70742 ML |
79 | unsigned front_seg_size = bio->bi_seg_front_size; |
80 | bool do_split = true; | |
81 | struct bio *new = NULL; | |
54efd50b | 82 | |
54efd50b | 83 | bio_for_each_segment(bv, bio, iter) { |
52cc6eea | 84 | if (sectors + (bv.bv_len >> 9) > queue_max_sectors(q)) |
54efd50b KO |
85 | goto split; |
86 | ||
87 | /* | |
88 | * If the queue doesn't support SG gaps and adding this | |
89 | * offset would create a gap, disallow it. | |
90 | */ | |
5014c311 | 91 | if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) |
54efd50b KO |
92 | goto split; |
93 | ||
5014c311 | 94 | if (bvprvp && blk_queue_cluster(q)) { |
54efd50b KO |
95 | if (seg_size + bv.bv_len > queue_max_segment_size(q)) |
96 | goto new_segment; | |
5014c311 | 97 | if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv)) |
54efd50b | 98 | goto new_segment; |
5014c311 | 99 | if (!BIOVEC_SEG_BOUNDARY(q, bvprvp, &bv)) |
54efd50b KO |
100 | goto new_segment; |
101 | ||
102 | seg_size += bv.bv_len; | |
103 | bvprv = bv; | |
578270bf | 104 | bvprvp = &bvprv; |
52cc6eea | 105 | sectors += bv.bv_len >> 9; |
a88d32af ML |
106 | |
107 | if (nsegs == 1 && seg_size > front_seg_size) | |
108 | front_seg_size = seg_size; | |
54efd50b KO |
109 | continue; |
110 | } | |
111 | new_segment: | |
112 | if (nsegs == queue_max_segments(q)) | |
113 | goto split; | |
114 | ||
115 | nsegs++; | |
116 | bvprv = bv; | |
578270bf | 117 | bvprvp = &bvprv; |
54efd50b | 118 | seg_size = bv.bv_len; |
52cc6eea | 119 | sectors += bv.bv_len >> 9; |
02e70742 ML |
120 | |
121 | if (nsegs == 1 && seg_size > front_seg_size) | |
122 | front_seg_size = seg_size; | |
54efd50b KO |
123 | } |
124 | ||
02e70742 | 125 | do_split = false; |
54efd50b | 126 | split: |
bdced438 | 127 | *segs = nsegs; |
02e70742 ML |
128 | |
129 | if (do_split) { | |
130 | new = bio_split(bio, sectors, GFP_NOIO, bs); | |
131 | if (new) | |
132 | bio = new; | |
133 | } | |
134 | ||
135 | bio->bi_seg_front_size = front_seg_size; | |
136 | if (seg_size > bio->bi_seg_back_size) | |
137 | bio->bi_seg_back_size = seg_size; | |
138 | ||
139 | return do_split ? new : NULL; | |
54efd50b KO |
140 | } |
141 | ||
142 | void blk_queue_split(struct request_queue *q, struct bio **bio, | |
143 | struct bio_set *bs) | |
144 | { | |
bdced438 ML |
145 | struct bio *split, *res; |
146 | unsigned nsegs; | |
54efd50b KO |
147 | |
148 | if ((*bio)->bi_rw & REQ_DISCARD) | |
bdced438 | 149 | split = blk_bio_discard_split(q, *bio, bs, &nsegs); |
54efd50b | 150 | else if ((*bio)->bi_rw & REQ_WRITE_SAME) |
bdced438 | 151 | split = blk_bio_write_same_split(q, *bio, bs, &nsegs); |
54efd50b | 152 | else |
bdced438 ML |
153 | split = blk_bio_segment_split(q, *bio, q->bio_split, &nsegs); |
154 | ||
155 | /* physical segments can be figured out during splitting */ | |
156 | res = split ? split : *bio; | |
157 | res->bi_phys_segments = nsegs; | |
158 | bio_set_flag(res, BIO_SEG_VALID); | |
54efd50b KO |
159 | |
160 | if (split) { | |
6ac45aeb ML |
161 | /* there isn't chance to merge the splitted bio */ |
162 | split->bi_rw |= REQ_NOMERGE; | |
163 | ||
54efd50b KO |
164 | bio_chain(split, *bio); |
165 | generic_make_request(*bio); | |
166 | *bio = split; | |
167 | } | |
168 | } | |
169 | EXPORT_SYMBOL(blk_queue_split); | |
170 | ||
1e428079 | 171 | static unsigned int __blk_recalc_rq_segments(struct request_queue *q, |
07388549 ML |
172 | struct bio *bio, |
173 | bool no_sg_merge) | |
d6d48196 | 174 | { |
7988613b | 175 | struct bio_vec bv, bvprv = { NULL }; |
54efd50b | 176 | int cluster, prev = 0; |
1e428079 | 177 | unsigned int seg_size, nr_phys_segs; |
59247eae | 178 | struct bio *fbio, *bbio; |
7988613b | 179 | struct bvec_iter iter; |
d6d48196 | 180 | |
1e428079 JA |
181 | if (!bio) |
182 | return 0; | |
d6d48196 | 183 | |
5cb8850c KO |
184 | /* |
185 | * This should probably be returning 0, but blk_add_request_payload() | |
186 | * (Christoph!!!!) | |
187 | */ | |
188 | if (bio->bi_rw & REQ_DISCARD) | |
189 | return 1; | |
190 | ||
191 | if (bio->bi_rw & REQ_WRITE_SAME) | |
192 | return 1; | |
193 | ||
1e428079 | 194 | fbio = bio; |
e692cb66 | 195 | cluster = blk_queue_cluster(q); |
5df97b91 | 196 | seg_size = 0; |
2c8919de | 197 | nr_phys_segs = 0; |
1e428079 | 198 | for_each_bio(bio) { |
7988613b | 199 | bio_for_each_segment(bv, bio, iter) { |
05f1dd53 JA |
200 | /* |
201 | * If SG merging is disabled, each bio vector is | |
202 | * a segment | |
203 | */ | |
204 | if (no_sg_merge) | |
205 | goto new_segment; | |
206 | ||
54efd50b | 207 | if (prev && cluster) { |
7988613b | 208 | if (seg_size + bv.bv_len |
ae03bf63 | 209 | > queue_max_segment_size(q)) |
1e428079 | 210 | goto new_segment; |
7988613b | 211 | if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv)) |
1e428079 | 212 | goto new_segment; |
7988613b | 213 | if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv)) |
1e428079 | 214 | goto new_segment; |
d6d48196 | 215 | |
7988613b | 216 | seg_size += bv.bv_len; |
1e428079 JA |
217 | bvprv = bv; |
218 | continue; | |
219 | } | |
d6d48196 | 220 | new_segment: |
1e428079 JA |
221 | if (nr_phys_segs == 1 && seg_size > |
222 | fbio->bi_seg_front_size) | |
223 | fbio->bi_seg_front_size = seg_size; | |
86771427 | 224 | |
1e428079 JA |
225 | nr_phys_segs++; |
226 | bvprv = bv; | |
54efd50b | 227 | prev = 1; |
7988613b | 228 | seg_size = bv.bv_len; |
1e428079 | 229 | } |
59247eae | 230 | bbio = bio; |
d6d48196 JA |
231 | } |
232 | ||
59247eae JA |
233 | if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) |
234 | fbio->bi_seg_front_size = seg_size; | |
235 | if (seg_size > bbio->bi_seg_back_size) | |
236 | bbio->bi_seg_back_size = seg_size; | |
1e428079 JA |
237 | |
238 | return nr_phys_segs; | |
239 | } | |
240 | ||
241 | void blk_recalc_rq_segments(struct request *rq) | |
242 | { | |
07388549 ML |
243 | bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, |
244 | &rq->q->queue_flags); | |
245 | ||
246 | rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio, | |
247 | no_sg_merge); | |
d6d48196 JA |
248 | } |
249 | ||
250 | void blk_recount_segments(struct request_queue *q, struct bio *bio) | |
251 | { | |
7f60dcaa ML |
252 | unsigned short seg_cnt; |
253 | ||
254 | /* estimate segment number by bi_vcnt for non-cloned bio */ | |
255 | if (bio_flagged(bio, BIO_CLONED)) | |
256 | seg_cnt = bio_segments(bio); | |
257 | else | |
258 | seg_cnt = bio->bi_vcnt; | |
764f612c | 259 | |
7f60dcaa ML |
260 | if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) && |
261 | (seg_cnt < queue_max_segments(q))) | |
262 | bio->bi_phys_segments = seg_cnt; | |
05f1dd53 JA |
263 | else { |
264 | struct bio *nxt = bio->bi_next; | |
265 | ||
266 | bio->bi_next = NULL; | |
7f60dcaa | 267 | bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false); |
05f1dd53 JA |
268 | bio->bi_next = nxt; |
269 | } | |
1e428079 | 270 | |
b7c44ed9 | 271 | bio_set_flag(bio, BIO_SEG_VALID); |
d6d48196 JA |
272 | } |
273 | EXPORT_SYMBOL(blk_recount_segments); | |
274 | ||
275 | static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, | |
276 | struct bio *nxt) | |
277 | { | |
2b8221e1 | 278 | struct bio_vec end_bv = { NULL }, nxt_bv; |
f619d254 KO |
279 | struct bvec_iter iter; |
280 | ||
e692cb66 | 281 | if (!blk_queue_cluster(q)) |
d6d48196 JA |
282 | return 0; |
283 | ||
86771427 | 284 | if (bio->bi_seg_back_size + nxt->bi_seg_front_size > |
ae03bf63 | 285 | queue_max_segment_size(q)) |
d6d48196 JA |
286 | return 0; |
287 | ||
e17fc0a1 DW |
288 | if (!bio_has_data(bio)) |
289 | return 1; | |
290 | ||
f619d254 KO |
291 | bio_for_each_segment(end_bv, bio, iter) |
292 | if (end_bv.bv_len == iter.bi_size) | |
293 | break; | |
294 | ||
295 | nxt_bv = bio_iovec(nxt); | |
296 | ||
297 | if (!BIOVEC_PHYS_MERGEABLE(&end_bv, &nxt_bv)) | |
e17fc0a1 DW |
298 | return 0; |
299 | ||
d6d48196 | 300 | /* |
e17fc0a1 | 301 | * bio and nxt are contiguous in memory; check if the queue allows |
d6d48196 JA |
302 | * these two to be merged into one |
303 | */ | |
f619d254 | 304 | if (BIOVEC_SEG_BOUNDARY(q, &end_bv, &nxt_bv)) |
d6d48196 JA |
305 | return 1; |
306 | ||
307 | return 0; | |
308 | } | |
309 | ||
7988613b | 310 | static inline void |
963ab9e5 | 311 | __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, |
7988613b | 312 | struct scatterlist *sglist, struct bio_vec *bvprv, |
963ab9e5 AH |
313 | struct scatterlist **sg, int *nsegs, int *cluster) |
314 | { | |
315 | ||
316 | int nbytes = bvec->bv_len; | |
317 | ||
7988613b | 318 | if (*sg && *cluster) { |
963ab9e5 AH |
319 | if ((*sg)->length + nbytes > queue_max_segment_size(q)) |
320 | goto new_segment; | |
321 | ||
7988613b | 322 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) |
963ab9e5 | 323 | goto new_segment; |
7988613b | 324 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) |
963ab9e5 AH |
325 | goto new_segment; |
326 | ||
327 | (*sg)->length += nbytes; | |
328 | } else { | |
329 | new_segment: | |
330 | if (!*sg) | |
331 | *sg = sglist; | |
332 | else { | |
333 | /* | |
334 | * If the driver previously mapped a shorter | |
335 | * list, we could see a termination bit | |
336 | * prematurely unless it fully inits the sg | |
337 | * table on each mapping. We KNOW that there | |
338 | * must be more entries here or the driver | |
339 | * would be buggy, so force clear the | |
340 | * termination bit to avoid doing a full | |
341 | * sg_init_table() in drivers for each command. | |
342 | */ | |
c8164d89 | 343 | sg_unmark_end(*sg); |
963ab9e5 AH |
344 | *sg = sg_next(*sg); |
345 | } | |
346 | ||
347 | sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); | |
348 | (*nsegs)++; | |
349 | } | |
7988613b | 350 | *bvprv = *bvec; |
963ab9e5 AH |
351 | } |
352 | ||
5cb8850c KO |
353 | static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, |
354 | struct scatterlist *sglist, | |
355 | struct scatterlist **sg) | |
d6d48196 | 356 | { |
2b8221e1 | 357 | struct bio_vec bvec, bvprv = { NULL }; |
5cb8850c | 358 | struct bvec_iter iter; |
d6d48196 JA |
359 | int nsegs, cluster; |
360 | ||
361 | nsegs = 0; | |
e692cb66 | 362 | cluster = blk_queue_cluster(q); |
d6d48196 | 363 | |
5cb8850c KO |
364 | if (bio->bi_rw & REQ_DISCARD) { |
365 | /* | |
366 | * This is a hack - drivers should be neither modifying the | |
367 | * biovec, nor relying on bi_vcnt - but because of | |
368 | * blk_add_request_payload(), a discard bio may or may not have | |
369 | * a payload we need to set up here (thank you Christoph) and | |
370 | * bi_vcnt is really the only way of telling if we need to. | |
371 | */ | |
372 | ||
373 | if (bio->bi_vcnt) | |
374 | goto single_segment; | |
375 | ||
376 | return 0; | |
377 | } | |
378 | ||
379 | if (bio->bi_rw & REQ_WRITE_SAME) { | |
380 | single_segment: | |
381 | *sg = sglist; | |
382 | bvec = bio_iovec(bio); | |
383 | sg_set_page(*sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset); | |
384 | return 1; | |
385 | } | |
386 | ||
387 | for_each_bio(bio) | |
388 | bio_for_each_segment(bvec, bio, iter) | |
389 | __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, | |
390 | &nsegs, &cluster); | |
d6d48196 | 391 | |
5cb8850c KO |
392 | return nsegs; |
393 | } | |
394 | ||
395 | /* | |
396 | * map a request to scatterlist, return number of sg entries setup. Caller | |
397 | * must make sure sg can hold rq->nr_phys_segments entries | |
398 | */ | |
399 | int blk_rq_map_sg(struct request_queue *q, struct request *rq, | |
400 | struct scatterlist *sglist) | |
401 | { | |
402 | struct scatterlist *sg = NULL; | |
403 | int nsegs = 0; | |
404 | ||
405 | if (rq->bio) | |
406 | nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); | |
f18573ab FT |
407 | |
408 | if (unlikely(rq->cmd_flags & REQ_COPY_USER) && | |
2e46e8b2 TH |
409 | (blk_rq_bytes(rq) & q->dma_pad_mask)) { |
410 | unsigned int pad_len = | |
411 | (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; | |
f18573ab FT |
412 | |
413 | sg->length += pad_len; | |
414 | rq->extra_len += pad_len; | |
415 | } | |
416 | ||
2fb98e84 | 417 | if (q->dma_drain_size && q->dma_drain_needed(rq)) { |
7b6d91da | 418 | if (rq->cmd_flags & REQ_WRITE) |
db0a2e00 TH |
419 | memset(q->dma_drain_buffer, 0, q->dma_drain_size); |
420 | ||
da81ed16 | 421 | sg_unmark_end(sg); |
d6d48196 JA |
422 | sg = sg_next(sg); |
423 | sg_set_page(sg, virt_to_page(q->dma_drain_buffer), | |
424 | q->dma_drain_size, | |
425 | ((unsigned long)q->dma_drain_buffer) & | |
426 | (PAGE_SIZE - 1)); | |
427 | nsegs++; | |
7a85f889 | 428 | rq->extra_len += q->dma_drain_size; |
d6d48196 JA |
429 | } |
430 | ||
431 | if (sg) | |
432 | sg_mark_end(sg); | |
433 | ||
12e57f59 ML |
434 | /* |
435 | * Something must have been wrong if the figured number of | |
436 | * segment is bigger than number of req's physical segments | |
437 | */ | |
438 | WARN_ON(nsegs > rq->nr_phys_segments); | |
439 | ||
d6d48196 JA |
440 | return nsegs; |
441 | } | |
d6d48196 JA |
442 | EXPORT_SYMBOL(blk_rq_map_sg); |
443 | ||
d6d48196 JA |
444 | static inline int ll_new_hw_segment(struct request_queue *q, |
445 | struct request *req, | |
446 | struct bio *bio) | |
447 | { | |
d6d48196 JA |
448 | int nr_phys_segs = bio_phys_segments(q, bio); |
449 | ||
13f05c8d MP |
450 | if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) |
451 | goto no_merge; | |
452 | ||
4eaf99be | 453 | if (blk_integrity_merge_bio(q, req, bio) == false) |
13f05c8d | 454 | goto no_merge; |
d6d48196 JA |
455 | |
456 | /* | |
457 | * This will form the start of a new hw segment. Bump both | |
458 | * counters. | |
459 | */ | |
d6d48196 JA |
460 | req->nr_phys_segments += nr_phys_segs; |
461 | return 1; | |
13f05c8d MP |
462 | |
463 | no_merge: | |
464 | req->cmd_flags |= REQ_NOMERGE; | |
465 | if (req == q->last_merge) | |
466 | q->last_merge = NULL; | |
467 | return 0; | |
d6d48196 JA |
468 | } |
469 | ||
470 | int ll_back_merge_fn(struct request_queue *q, struct request *req, | |
471 | struct bio *bio) | |
472 | { | |
5e7c4274 JA |
473 | if (req_gap_back_merge(req, bio)) |
474 | return 0; | |
7f39add3 SG |
475 | if (blk_integrity_rq(req) && |
476 | integrity_req_gap_back_merge(req, bio)) | |
477 | return 0; | |
f31dc1cd MP |
478 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
479 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
480 | req->cmd_flags |= REQ_NOMERGE; |
481 | if (req == q->last_merge) | |
482 | q->last_merge = NULL; | |
483 | return 0; | |
484 | } | |
2cdf79ca | 485 | if (!bio_flagged(req->biotail, BIO_SEG_VALID)) |
d6d48196 | 486 | blk_recount_segments(q, req->biotail); |
2cdf79ca | 487 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 488 | blk_recount_segments(q, bio); |
d6d48196 JA |
489 | |
490 | return ll_new_hw_segment(q, req, bio); | |
491 | } | |
492 | ||
6728cb0e | 493 | int ll_front_merge_fn(struct request_queue *q, struct request *req, |
d6d48196 JA |
494 | struct bio *bio) |
495 | { | |
5e7c4274 JA |
496 | |
497 | if (req_gap_front_merge(req, bio)) | |
498 | return 0; | |
7f39add3 SG |
499 | if (blk_integrity_rq(req) && |
500 | integrity_req_gap_front_merge(req, bio)) | |
501 | return 0; | |
f31dc1cd MP |
502 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
503 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
504 | req->cmd_flags |= REQ_NOMERGE; |
505 | if (req == q->last_merge) | |
506 | q->last_merge = NULL; | |
507 | return 0; | |
508 | } | |
2cdf79ca | 509 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 510 | blk_recount_segments(q, bio); |
2cdf79ca | 511 | if (!bio_flagged(req->bio, BIO_SEG_VALID)) |
d6d48196 | 512 | blk_recount_segments(q, req->bio); |
d6d48196 JA |
513 | |
514 | return ll_new_hw_segment(q, req, bio); | |
515 | } | |
516 | ||
e7e24500 JA |
517 | /* |
518 | * blk-mq uses req->special to carry normal driver per-request payload, it | |
519 | * does not indicate a prepared command that we cannot merge with. | |
520 | */ | |
521 | static bool req_no_special_merge(struct request *req) | |
522 | { | |
523 | struct request_queue *q = req->q; | |
524 | ||
525 | return !q->mq_ops && req->special; | |
526 | } | |
527 | ||
d6d48196 JA |
528 | static int ll_merge_requests_fn(struct request_queue *q, struct request *req, |
529 | struct request *next) | |
530 | { | |
531 | int total_phys_segments; | |
86771427 FT |
532 | unsigned int seg_size = |
533 | req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; | |
d6d48196 JA |
534 | |
535 | /* | |
536 | * First check if the either of the requests are re-queued | |
537 | * requests. Can't merge them if they are. | |
538 | */ | |
e7e24500 | 539 | if (req_no_special_merge(req) || req_no_special_merge(next)) |
d6d48196 JA |
540 | return 0; |
541 | ||
5e7c4274 | 542 | if (req_gap_back_merge(req, next->bio)) |
854fbb9c KB |
543 | return 0; |
544 | ||
d6d48196 JA |
545 | /* |
546 | * Will it become too large? | |
547 | */ | |
f31dc1cd MP |
548 | if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > |
549 | blk_rq_get_max_sectors(req)) | |
d6d48196 JA |
550 | return 0; |
551 | ||
552 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
86771427 FT |
553 | if (blk_phys_contig_segment(q, req->biotail, next->bio)) { |
554 | if (req->nr_phys_segments == 1) | |
555 | req->bio->bi_seg_front_size = seg_size; | |
556 | if (next->nr_phys_segments == 1) | |
557 | next->biotail->bi_seg_back_size = seg_size; | |
d6d48196 | 558 | total_phys_segments--; |
86771427 | 559 | } |
d6d48196 | 560 | |
8a78362c | 561 | if (total_phys_segments > queue_max_segments(q)) |
d6d48196 JA |
562 | return 0; |
563 | ||
4eaf99be | 564 | if (blk_integrity_merge_rq(q, req, next) == false) |
13f05c8d MP |
565 | return 0; |
566 | ||
d6d48196 JA |
567 | /* Merge is OK... */ |
568 | req->nr_phys_segments = total_phys_segments; | |
d6d48196 JA |
569 | return 1; |
570 | } | |
571 | ||
80a761fd TH |
572 | /** |
573 | * blk_rq_set_mixed_merge - mark a request as mixed merge | |
574 | * @rq: request to mark as mixed merge | |
575 | * | |
576 | * Description: | |
577 | * @rq is about to be mixed merged. Make sure the attributes | |
578 | * which can be mixed are set in each bio and mark @rq as mixed | |
579 | * merged. | |
580 | */ | |
581 | void blk_rq_set_mixed_merge(struct request *rq) | |
582 | { | |
583 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
584 | struct bio *bio; | |
585 | ||
586 | if (rq->cmd_flags & REQ_MIXED_MERGE) | |
587 | return; | |
588 | ||
589 | /* | |
590 | * @rq will no longer represent mixable attributes for all the | |
591 | * contained bios. It will just track those of the first one. | |
592 | * Distributes the attributs to each bio. | |
593 | */ | |
594 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
595 | WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) && | |
596 | (bio->bi_rw & REQ_FAILFAST_MASK) != ff); | |
597 | bio->bi_rw |= ff; | |
598 | } | |
599 | rq->cmd_flags |= REQ_MIXED_MERGE; | |
600 | } | |
601 | ||
26308eab JM |
602 | static void blk_account_io_merge(struct request *req) |
603 | { | |
604 | if (blk_do_io_stat(req)) { | |
605 | struct hd_struct *part; | |
606 | int cpu; | |
607 | ||
608 | cpu = part_stat_lock(); | |
09e099d4 | 609 | part = req->part; |
26308eab JM |
610 | |
611 | part_round_stats(cpu, part); | |
316d315b | 612 | part_dec_in_flight(part, rq_data_dir(req)); |
26308eab | 613 | |
6c23a968 | 614 | hd_struct_put(part); |
26308eab JM |
615 | part_stat_unlock(); |
616 | } | |
617 | } | |
618 | ||
d6d48196 JA |
619 | /* |
620 | * Has to be called with the request spinlock acquired | |
621 | */ | |
622 | static int attempt_merge(struct request_queue *q, struct request *req, | |
623 | struct request *next) | |
624 | { | |
625 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
626 | return 0; | |
627 | ||
f31dc1cd MP |
628 | if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags)) |
629 | return 0; | |
630 | ||
d6d48196 JA |
631 | /* |
632 | * not contiguous | |
633 | */ | |
83096ebf | 634 | if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next)) |
d6d48196 JA |
635 | return 0; |
636 | ||
637 | if (rq_data_dir(req) != rq_data_dir(next) | |
638 | || req->rq_disk != next->rq_disk | |
e7e24500 | 639 | || req_no_special_merge(next)) |
d6d48196 JA |
640 | return 0; |
641 | ||
4363ac7c MP |
642 | if (req->cmd_flags & REQ_WRITE_SAME && |
643 | !blk_write_same_mergeable(req->bio, next->bio)) | |
644 | return 0; | |
645 | ||
d6d48196 JA |
646 | /* |
647 | * If we are allowed to merge, then append bio list | |
648 | * from next to rq and release next. merge_requests_fn | |
649 | * will have updated segment counts, update sector | |
650 | * counts here. | |
651 | */ | |
652 | if (!ll_merge_requests_fn(q, req, next)) | |
653 | return 0; | |
654 | ||
80a761fd TH |
655 | /* |
656 | * If failfast settings disagree or any of the two is already | |
657 | * a mixed merge, mark both as mixed before proceeding. This | |
658 | * makes sure that all involved bios have mixable attributes | |
659 | * set properly. | |
660 | */ | |
661 | if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE || | |
662 | (req->cmd_flags & REQ_FAILFAST_MASK) != | |
663 | (next->cmd_flags & REQ_FAILFAST_MASK)) { | |
664 | blk_rq_set_mixed_merge(req); | |
665 | blk_rq_set_mixed_merge(next); | |
666 | } | |
667 | ||
d6d48196 JA |
668 | /* |
669 | * At this point we have either done a back merge | |
670 | * or front merge. We need the smaller start_time of | |
671 | * the merged requests to be the current request | |
672 | * for accounting purposes. | |
673 | */ | |
674 | if (time_after(req->start_time, next->start_time)) | |
675 | req->start_time = next->start_time; | |
676 | ||
677 | req->biotail->bi_next = next->bio; | |
678 | req->biotail = next->biotail; | |
679 | ||
a2dec7b3 | 680 | req->__data_len += blk_rq_bytes(next); |
d6d48196 JA |
681 | |
682 | elv_merge_requests(q, req, next); | |
683 | ||
42dad764 JM |
684 | /* |
685 | * 'next' is going away, so update stats accordingly | |
686 | */ | |
687 | blk_account_io_merge(next); | |
d6d48196 JA |
688 | |
689 | req->ioprio = ioprio_best(req->ioprio, next->ioprio); | |
ab780f1e JA |
690 | if (blk_rq_cpu_valid(next)) |
691 | req->cpu = next->cpu; | |
d6d48196 | 692 | |
1cd96c24 BH |
693 | /* owner-ship of bio passed from next to req */ |
694 | next->bio = NULL; | |
d6d48196 JA |
695 | __blk_put_request(q, next); |
696 | return 1; | |
697 | } | |
698 | ||
699 | int attempt_back_merge(struct request_queue *q, struct request *rq) | |
700 | { | |
701 | struct request *next = elv_latter_request(q, rq); | |
702 | ||
703 | if (next) | |
704 | return attempt_merge(q, rq, next); | |
705 | ||
706 | return 0; | |
707 | } | |
708 | ||
709 | int attempt_front_merge(struct request_queue *q, struct request *rq) | |
710 | { | |
711 | struct request *prev = elv_former_request(q, rq); | |
712 | ||
713 | if (prev) | |
714 | return attempt_merge(q, prev, rq); | |
715 | ||
716 | return 0; | |
717 | } | |
5e84ea3a JA |
718 | |
719 | int blk_attempt_req_merge(struct request_queue *q, struct request *rq, | |
720 | struct request *next) | |
721 | { | |
722 | return attempt_merge(q, rq, next); | |
723 | } | |
050c8ea8 TH |
724 | |
725 | bool blk_rq_merge_ok(struct request *rq, struct bio *bio) | |
726 | { | |
e2a60da7 | 727 | if (!rq_mergeable(rq) || !bio_mergeable(bio)) |
050c8ea8 TH |
728 | return false; |
729 | ||
f31dc1cd MP |
730 | if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw)) |
731 | return false; | |
732 | ||
050c8ea8 TH |
733 | /* different data direction or already started, don't merge */ |
734 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
735 | return false; | |
736 | ||
737 | /* must be same device and not a special request */ | |
e7e24500 | 738 | if (rq->rq_disk != bio->bi_bdev->bd_disk || req_no_special_merge(rq)) |
050c8ea8 TH |
739 | return false; |
740 | ||
741 | /* only merge integrity protected bio into ditto rq */ | |
4eaf99be | 742 | if (blk_integrity_merge_bio(rq->q, rq, bio) == false) |
050c8ea8 TH |
743 | return false; |
744 | ||
4363ac7c MP |
745 | /* must be using the same buffer */ |
746 | if (rq->cmd_flags & REQ_WRITE_SAME && | |
747 | !blk_write_same_mergeable(rq->bio, bio)) | |
748 | return false; | |
749 | ||
050c8ea8 TH |
750 | return true; |
751 | } | |
752 | ||
753 | int blk_try_merge(struct request *rq, struct bio *bio) | |
754 | { | |
4f024f37 | 755 | if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) |
050c8ea8 | 756 | return ELEVATOR_BACK_MERGE; |
4f024f37 | 757 | else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) |
050c8ea8 TH |
758 | return ELEVATOR_FRONT_MERGE; |
759 | return ELEVATOR_NO_MERGE; | |
760 | } |