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 | ||
1e428079 | 12 | static unsigned int __blk_recalc_rq_segments(struct request_queue *q, |
59247eae | 13 | struct bio *bio) |
d6d48196 | 14 | { |
7988613b KO |
15 | struct bio_vec bv, bvprv = { NULL }; |
16 | int cluster, high, highprv = 1; | |
1e428079 | 17 | unsigned int seg_size, nr_phys_segs; |
59247eae | 18 | struct bio *fbio, *bbio; |
7988613b | 19 | struct bvec_iter iter; |
d6d48196 | 20 | |
1e428079 JA |
21 | if (!bio) |
22 | return 0; | |
d6d48196 | 23 | |
5cb8850c KO |
24 | /* |
25 | * This should probably be returning 0, but blk_add_request_payload() | |
26 | * (Christoph!!!!) | |
27 | */ | |
28 | if (bio->bi_rw & REQ_DISCARD) | |
29 | return 1; | |
30 | ||
31 | if (bio->bi_rw & REQ_WRITE_SAME) | |
32 | return 1; | |
33 | ||
1e428079 | 34 | fbio = bio; |
e692cb66 | 35 | cluster = blk_queue_cluster(q); |
5df97b91 | 36 | seg_size = 0; |
2c8919de | 37 | nr_phys_segs = 0; |
1e428079 | 38 | for_each_bio(bio) { |
7988613b | 39 | bio_for_each_segment(bv, bio, iter) { |
1e428079 JA |
40 | /* |
41 | * the trick here is making sure that a high page is | |
42 | * never considered part of another segment, since that | |
43 | * might change with the bounce page. | |
44 | */ | |
7988613b KO |
45 | high = page_to_pfn(bv.bv_page) > queue_bounce_pfn(q); |
46 | if (!high && !highprv && cluster) { | |
47 | if (seg_size + bv.bv_len | |
ae03bf63 | 48 | > queue_max_segment_size(q)) |
1e428079 | 49 | goto new_segment; |
7988613b | 50 | if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv)) |
1e428079 | 51 | goto new_segment; |
7988613b | 52 | if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv)) |
1e428079 | 53 | goto new_segment; |
d6d48196 | 54 | |
7988613b | 55 | seg_size += bv.bv_len; |
1e428079 JA |
56 | bvprv = bv; |
57 | continue; | |
58 | } | |
d6d48196 | 59 | new_segment: |
1e428079 JA |
60 | if (nr_phys_segs == 1 && seg_size > |
61 | fbio->bi_seg_front_size) | |
62 | fbio->bi_seg_front_size = seg_size; | |
86771427 | 63 | |
1e428079 JA |
64 | nr_phys_segs++; |
65 | bvprv = bv; | |
7988613b | 66 | seg_size = bv.bv_len; |
1e428079 JA |
67 | highprv = high; |
68 | } | |
59247eae | 69 | bbio = bio; |
d6d48196 JA |
70 | } |
71 | ||
59247eae JA |
72 | if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) |
73 | fbio->bi_seg_front_size = seg_size; | |
74 | if (seg_size > bbio->bi_seg_back_size) | |
75 | bbio->bi_seg_back_size = seg_size; | |
1e428079 JA |
76 | |
77 | return nr_phys_segs; | |
78 | } | |
79 | ||
80 | void blk_recalc_rq_segments(struct request *rq) | |
81 | { | |
59247eae | 82 | rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio); |
d6d48196 JA |
83 | } |
84 | ||
85 | void blk_recount_segments(struct request_queue *q, struct bio *bio) | |
86 | { | |
d6d48196 | 87 | struct bio *nxt = bio->bi_next; |
1e428079 | 88 | |
d6d48196 | 89 | bio->bi_next = NULL; |
59247eae | 90 | bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio); |
d6d48196 | 91 | bio->bi_next = nxt; |
d6d48196 JA |
92 | bio->bi_flags |= (1 << BIO_SEG_VALID); |
93 | } | |
94 | EXPORT_SYMBOL(blk_recount_segments); | |
95 | ||
96 | static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, | |
97 | struct bio *nxt) | |
98 | { | |
2b8221e1 | 99 | struct bio_vec end_bv = { NULL }, nxt_bv; |
f619d254 KO |
100 | struct bvec_iter iter; |
101 | ||
e692cb66 | 102 | if (!blk_queue_cluster(q)) |
d6d48196 JA |
103 | return 0; |
104 | ||
86771427 | 105 | if (bio->bi_seg_back_size + nxt->bi_seg_front_size > |
ae03bf63 | 106 | queue_max_segment_size(q)) |
d6d48196 JA |
107 | return 0; |
108 | ||
e17fc0a1 DW |
109 | if (!bio_has_data(bio)) |
110 | return 1; | |
111 | ||
f619d254 KO |
112 | bio_for_each_segment(end_bv, bio, iter) |
113 | if (end_bv.bv_len == iter.bi_size) | |
114 | break; | |
115 | ||
116 | nxt_bv = bio_iovec(nxt); | |
117 | ||
118 | if (!BIOVEC_PHYS_MERGEABLE(&end_bv, &nxt_bv)) | |
e17fc0a1 DW |
119 | return 0; |
120 | ||
d6d48196 | 121 | /* |
e17fc0a1 | 122 | * bio and nxt are contiguous in memory; check if the queue allows |
d6d48196 JA |
123 | * these two to be merged into one |
124 | */ | |
f619d254 | 125 | if (BIOVEC_SEG_BOUNDARY(q, &end_bv, &nxt_bv)) |
d6d48196 JA |
126 | return 1; |
127 | ||
128 | return 0; | |
129 | } | |
130 | ||
7988613b | 131 | static inline void |
963ab9e5 | 132 | __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, |
7988613b | 133 | struct scatterlist *sglist, struct bio_vec *bvprv, |
963ab9e5 AH |
134 | struct scatterlist **sg, int *nsegs, int *cluster) |
135 | { | |
136 | ||
137 | int nbytes = bvec->bv_len; | |
138 | ||
7988613b | 139 | if (*sg && *cluster) { |
963ab9e5 AH |
140 | if ((*sg)->length + nbytes > queue_max_segment_size(q)) |
141 | goto new_segment; | |
142 | ||
7988613b | 143 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) |
963ab9e5 | 144 | goto new_segment; |
7988613b | 145 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) |
963ab9e5 AH |
146 | goto new_segment; |
147 | ||
148 | (*sg)->length += nbytes; | |
149 | } else { | |
150 | new_segment: | |
151 | if (!*sg) | |
152 | *sg = sglist; | |
153 | else { | |
154 | /* | |
155 | * If the driver previously mapped a shorter | |
156 | * list, we could see a termination bit | |
157 | * prematurely unless it fully inits the sg | |
158 | * table on each mapping. We KNOW that there | |
159 | * must be more entries here or the driver | |
160 | * would be buggy, so force clear the | |
161 | * termination bit to avoid doing a full | |
162 | * sg_init_table() in drivers for each command. | |
163 | */ | |
c8164d89 | 164 | sg_unmark_end(*sg); |
963ab9e5 AH |
165 | *sg = sg_next(*sg); |
166 | } | |
167 | ||
168 | sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); | |
169 | (*nsegs)++; | |
170 | } | |
7988613b | 171 | *bvprv = *bvec; |
963ab9e5 AH |
172 | } |
173 | ||
5cb8850c KO |
174 | static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, |
175 | struct scatterlist *sglist, | |
176 | struct scatterlist **sg) | |
d6d48196 | 177 | { |
2b8221e1 | 178 | struct bio_vec bvec, bvprv = { NULL }; |
5cb8850c | 179 | struct bvec_iter iter; |
d6d48196 JA |
180 | int nsegs, cluster; |
181 | ||
182 | nsegs = 0; | |
e692cb66 | 183 | cluster = blk_queue_cluster(q); |
d6d48196 | 184 | |
5cb8850c KO |
185 | if (bio->bi_rw & REQ_DISCARD) { |
186 | /* | |
187 | * This is a hack - drivers should be neither modifying the | |
188 | * biovec, nor relying on bi_vcnt - but because of | |
189 | * blk_add_request_payload(), a discard bio may or may not have | |
190 | * a payload we need to set up here (thank you Christoph) and | |
191 | * bi_vcnt is really the only way of telling if we need to. | |
192 | */ | |
193 | ||
194 | if (bio->bi_vcnt) | |
195 | goto single_segment; | |
196 | ||
197 | return 0; | |
198 | } | |
199 | ||
200 | if (bio->bi_rw & REQ_WRITE_SAME) { | |
201 | single_segment: | |
202 | *sg = sglist; | |
203 | bvec = bio_iovec(bio); | |
204 | sg_set_page(*sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset); | |
205 | return 1; | |
206 | } | |
207 | ||
208 | for_each_bio(bio) | |
209 | bio_for_each_segment(bvec, bio, iter) | |
210 | __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, | |
211 | &nsegs, &cluster); | |
d6d48196 | 212 | |
5cb8850c KO |
213 | return nsegs; |
214 | } | |
215 | ||
216 | /* | |
217 | * map a request to scatterlist, return number of sg entries setup. Caller | |
218 | * must make sure sg can hold rq->nr_phys_segments entries | |
219 | */ | |
220 | int blk_rq_map_sg(struct request_queue *q, struct request *rq, | |
221 | struct scatterlist *sglist) | |
222 | { | |
223 | struct scatterlist *sg = NULL; | |
224 | int nsegs = 0; | |
225 | ||
226 | if (rq->bio) | |
227 | nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); | |
f18573ab FT |
228 | |
229 | if (unlikely(rq->cmd_flags & REQ_COPY_USER) && | |
2e46e8b2 TH |
230 | (blk_rq_bytes(rq) & q->dma_pad_mask)) { |
231 | unsigned int pad_len = | |
232 | (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; | |
f18573ab FT |
233 | |
234 | sg->length += pad_len; | |
235 | rq->extra_len += pad_len; | |
236 | } | |
237 | ||
2fb98e84 | 238 | if (q->dma_drain_size && q->dma_drain_needed(rq)) { |
7b6d91da | 239 | if (rq->cmd_flags & REQ_WRITE) |
db0a2e00 TH |
240 | memset(q->dma_drain_buffer, 0, q->dma_drain_size); |
241 | ||
d6d48196 JA |
242 | sg->page_link &= ~0x02; |
243 | sg = sg_next(sg); | |
244 | sg_set_page(sg, virt_to_page(q->dma_drain_buffer), | |
245 | q->dma_drain_size, | |
246 | ((unsigned long)q->dma_drain_buffer) & | |
247 | (PAGE_SIZE - 1)); | |
248 | nsegs++; | |
7a85f889 | 249 | rq->extra_len += q->dma_drain_size; |
d6d48196 JA |
250 | } |
251 | ||
252 | if (sg) | |
253 | sg_mark_end(sg); | |
254 | ||
255 | return nsegs; | |
256 | } | |
d6d48196 JA |
257 | EXPORT_SYMBOL(blk_rq_map_sg); |
258 | ||
85b9f66a AH |
259 | /** |
260 | * blk_bio_map_sg - map a bio to a scatterlist | |
261 | * @q: request_queue in question | |
262 | * @bio: bio being mapped | |
263 | * @sglist: scatterlist being mapped | |
264 | * | |
265 | * Note: | |
266 | * Caller must make sure sg can hold bio->bi_phys_segments entries | |
267 | * | |
268 | * Will return the number of sg entries setup | |
269 | */ | |
270 | int blk_bio_map_sg(struct request_queue *q, struct bio *bio, | |
271 | struct scatterlist *sglist) | |
272 | { | |
5cb8850c KO |
273 | struct scatterlist *sg = NULL; |
274 | int nsegs; | |
275 | struct bio *next = bio->bi_next; | |
276 | bio->bi_next = NULL; | |
85b9f66a | 277 | |
5cb8850c KO |
278 | nsegs = __blk_bios_map_sg(q, bio, sglist, &sg); |
279 | bio->bi_next = next; | |
85b9f66a AH |
280 | if (sg) |
281 | sg_mark_end(sg); | |
282 | ||
283 | BUG_ON(bio->bi_phys_segments && nsegs > bio->bi_phys_segments); | |
284 | return nsegs; | |
285 | } | |
286 | EXPORT_SYMBOL(blk_bio_map_sg); | |
287 | ||
d6d48196 JA |
288 | static inline int ll_new_hw_segment(struct request_queue *q, |
289 | struct request *req, | |
290 | struct bio *bio) | |
291 | { | |
d6d48196 JA |
292 | int nr_phys_segs = bio_phys_segments(q, bio); |
293 | ||
13f05c8d MP |
294 | if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) |
295 | goto no_merge; | |
296 | ||
297 | if (bio_integrity(bio) && blk_integrity_merge_bio(q, req, bio)) | |
298 | goto no_merge; | |
d6d48196 JA |
299 | |
300 | /* | |
301 | * This will form the start of a new hw segment. Bump both | |
302 | * counters. | |
303 | */ | |
d6d48196 JA |
304 | req->nr_phys_segments += nr_phys_segs; |
305 | return 1; | |
13f05c8d MP |
306 | |
307 | no_merge: | |
308 | req->cmd_flags |= REQ_NOMERGE; | |
309 | if (req == q->last_merge) | |
310 | q->last_merge = NULL; | |
311 | return 0; | |
d6d48196 JA |
312 | } |
313 | ||
314 | int ll_back_merge_fn(struct request_queue *q, struct request *req, | |
315 | struct bio *bio) | |
316 | { | |
f31dc1cd MP |
317 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
318 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
319 | req->cmd_flags |= REQ_NOMERGE; |
320 | if (req == q->last_merge) | |
321 | q->last_merge = NULL; | |
322 | return 0; | |
323 | } | |
2cdf79ca | 324 | if (!bio_flagged(req->biotail, BIO_SEG_VALID)) |
d6d48196 | 325 | blk_recount_segments(q, req->biotail); |
2cdf79ca | 326 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 327 | blk_recount_segments(q, bio); |
d6d48196 JA |
328 | |
329 | return ll_new_hw_segment(q, req, bio); | |
330 | } | |
331 | ||
6728cb0e | 332 | int ll_front_merge_fn(struct request_queue *q, struct request *req, |
d6d48196 JA |
333 | struct bio *bio) |
334 | { | |
f31dc1cd MP |
335 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
336 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
337 | req->cmd_flags |= REQ_NOMERGE; |
338 | if (req == q->last_merge) | |
339 | q->last_merge = NULL; | |
340 | return 0; | |
341 | } | |
2cdf79ca | 342 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 343 | blk_recount_segments(q, bio); |
2cdf79ca | 344 | if (!bio_flagged(req->bio, BIO_SEG_VALID)) |
d6d48196 | 345 | blk_recount_segments(q, req->bio); |
d6d48196 JA |
346 | |
347 | return ll_new_hw_segment(q, req, bio); | |
348 | } | |
349 | ||
e7e24500 JA |
350 | /* |
351 | * blk-mq uses req->special to carry normal driver per-request payload, it | |
352 | * does not indicate a prepared command that we cannot merge with. | |
353 | */ | |
354 | static bool req_no_special_merge(struct request *req) | |
355 | { | |
356 | struct request_queue *q = req->q; | |
357 | ||
358 | return !q->mq_ops && req->special; | |
359 | } | |
360 | ||
d6d48196 JA |
361 | static int ll_merge_requests_fn(struct request_queue *q, struct request *req, |
362 | struct request *next) | |
363 | { | |
364 | int total_phys_segments; | |
86771427 FT |
365 | unsigned int seg_size = |
366 | req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; | |
d6d48196 JA |
367 | |
368 | /* | |
369 | * First check if the either of the requests are re-queued | |
370 | * requests. Can't merge them if they are. | |
371 | */ | |
e7e24500 | 372 | if (req_no_special_merge(req) || req_no_special_merge(next)) |
d6d48196 JA |
373 | return 0; |
374 | ||
375 | /* | |
376 | * Will it become too large? | |
377 | */ | |
f31dc1cd MP |
378 | if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > |
379 | blk_rq_get_max_sectors(req)) | |
d6d48196 JA |
380 | return 0; |
381 | ||
382 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
86771427 FT |
383 | if (blk_phys_contig_segment(q, req->biotail, next->bio)) { |
384 | if (req->nr_phys_segments == 1) | |
385 | req->bio->bi_seg_front_size = seg_size; | |
386 | if (next->nr_phys_segments == 1) | |
387 | next->biotail->bi_seg_back_size = seg_size; | |
d6d48196 | 388 | total_phys_segments--; |
86771427 | 389 | } |
d6d48196 | 390 | |
8a78362c | 391 | if (total_phys_segments > queue_max_segments(q)) |
d6d48196 JA |
392 | return 0; |
393 | ||
13f05c8d MP |
394 | if (blk_integrity_rq(req) && blk_integrity_merge_rq(q, req, next)) |
395 | return 0; | |
396 | ||
d6d48196 JA |
397 | /* Merge is OK... */ |
398 | req->nr_phys_segments = total_phys_segments; | |
d6d48196 JA |
399 | return 1; |
400 | } | |
401 | ||
80a761fd TH |
402 | /** |
403 | * blk_rq_set_mixed_merge - mark a request as mixed merge | |
404 | * @rq: request to mark as mixed merge | |
405 | * | |
406 | * Description: | |
407 | * @rq is about to be mixed merged. Make sure the attributes | |
408 | * which can be mixed are set in each bio and mark @rq as mixed | |
409 | * merged. | |
410 | */ | |
411 | void blk_rq_set_mixed_merge(struct request *rq) | |
412 | { | |
413 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
414 | struct bio *bio; | |
415 | ||
416 | if (rq->cmd_flags & REQ_MIXED_MERGE) | |
417 | return; | |
418 | ||
419 | /* | |
420 | * @rq will no longer represent mixable attributes for all the | |
421 | * contained bios. It will just track those of the first one. | |
422 | * Distributes the attributs to each bio. | |
423 | */ | |
424 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
425 | WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) && | |
426 | (bio->bi_rw & REQ_FAILFAST_MASK) != ff); | |
427 | bio->bi_rw |= ff; | |
428 | } | |
429 | rq->cmd_flags |= REQ_MIXED_MERGE; | |
430 | } | |
431 | ||
26308eab JM |
432 | static void blk_account_io_merge(struct request *req) |
433 | { | |
434 | if (blk_do_io_stat(req)) { | |
435 | struct hd_struct *part; | |
436 | int cpu; | |
437 | ||
438 | cpu = part_stat_lock(); | |
09e099d4 | 439 | part = req->part; |
26308eab JM |
440 | |
441 | part_round_stats(cpu, part); | |
316d315b | 442 | part_dec_in_flight(part, rq_data_dir(req)); |
26308eab | 443 | |
6c23a968 | 444 | hd_struct_put(part); |
26308eab JM |
445 | part_stat_unlock(); |
446 | } | |
447 | } | |
448 | ||
d6d48196 JA |
449 | /* |
450 | * Has to be called with the request spinlock acquired | |
451 | */ | |
452 | static int attempt_merge(struct request_queue *q, struct request *req, | |
453 | struct request *next) | |
454 | { | |
455 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
456 | return 0; | |
457 | ||
f31dc1cd MP |
458 | if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags)) |
459 | return 0; | |
460 | ||
d6d48196 JA |
461 | /* |
462 | * not contiguous | |
463 | */ | |
83096ebf | 464 | if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next)) |
d6d48196 JA |
465 | return 0; |
466 | ||
467 | if (rq_data_dir(req) != rq_data_dir(next) | |
468 | || req->rq_disk != next->rq_disk | |
e7e24500 | 469 | || req_no_special_merge(next)) |
d6d48196 JA |
470 | return 0; |
471 | ||
4363ac7c MP |
472 | if (req->cmd_flags & REQ_WRITE_SAME && |
473 | !blk_write_same_mergeable(req->bio, next->bio)) | |
474 | return 0; | |
475 | ||
d6d48196 JA |
476 | /* |
477 | * If we are allowed to merge, then append bio list | |
478 | * from next to rq and release next. merge_requests_fn | |
479 | * will have updated segment counts, update sector | |
480 | * counts here. | |
481 | */ | |
482 | if (!ll_merge_requests_fn(q, req, next)) | |
483 | return 0; | |
484 | ||
80a761fd TH |
485 | /* |
486 | * If failfast settings disagree or any of the two is already | |
487 | * a mixed merge, mark both as mixed before proceeding. This | |
488 | * makes sure that all involved bios have mixable attributes | |
489 | * set properly. | |
490 | */ | |
491 | if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE || | |
492 | (req->cmd_flags & REQ_FAILFAST_MASK) != | |
493 | (next->cmd_flags & REQ_FAILFAST_MASK)) { | |
494 | blk_rq_set_mixed_merge(req); | |
495 | blk_rq_set_mixed_merge(next); | |
496 | } | |
497 | ||
d6d48196 JA |
498 | /* |
499 | * At this point we have either done a back merge | |
500 | * or front merge. We need the smaller start_time of | |
501 | * the merged requests to be the current request | |
502 | * for accounting purposes. | |
503 | */ | |
504 | if (time_after(req->start_time, next->start_time)) | |
505 | req->start_time = next->start_time; | |
506 | ||
507 | req->biotail->bi_next = next->bio; | |
508 | req->biotail = next->biotail; | |
509 | ||
a2dec7b3 | 510 | req->__data_len += blk_rq_bytes(next); |
d6d48196 JA |
511 | |
512 | elv_merge_requests(q, req, next); | |
513 | ||
42dad764 JM |
514 | /* |
515 | * 'next' is going away, so update stats accordingly | |
516 | */ | |
517 | blk_account_io_merge(next); | |
d6d48196 JA |
518 | |
519 | req->ioprio = ioprio_best(req->ioprio, next->ioprio); | |
ab780f1e JA |
520 | if (blk_rq_cpu_valid(next)) |
521 | req->cpu = next->cpu; | |
d6d48196 | 522 | |
1cd96c24 BH |
523 | /* owner-ship of bio passed from next to req */ |
524 | next->bio = NULL; | |
d6d48196 JA |
525 | __blk_put_request(q, next); |
526 | return 1; | |
527 | } | |
528 | ||
529 | int attempt_back_merge(struct request_queue *q, struct request *rq) | |
530 | { | |
531 | struct request *next = elv_latter_request(q, rq); | |
532 | ||
533 | if (next) | |
534 | return attempt_merge(q, rq, next); | |
535 | ||
536 | return 0; | |
537 | } | |
538 | ||
539 | int attempt_front_merge(struct request_queue *q, struct request *rq) | |
540 | { | |
541 | struct request *prev = elv_former_request(q, rq); | |
542 | ||
543 | if (prev) | |
544 | return attempt_merge(q, prev, rq); | |
545 | ||
546 | return 0; | |
547 | } | |
5e84ea3a JA |
548 | |
549 | int blk_attempt_req_merge(struct request_queue *q, struct request *rq, | |
550 | struct request *next) | |
551 | { | |
552 | return attempt_merge(q, rq, next); | |
553 | } | |
050c8ea8 TH |
554 | |
555 | bool blk_rq_merge_ok(struct request *rq, struct bio *bio) | |
556 | { | |
e2a60da7 | 557 | if (!rq_mergeable(rq) || !bio_mergeable(bio)) |
050c8ea8 TH |
558 | return false; |
559 | ||
f31dc1cd MP |
560 | if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw)) |
561 | return false; | |
562 | ||
050c8ea8 TH |
563 | /* different data direction or already started, don't merge */ |
564 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
565 | return false; | |
566 | ||
567 | /* must be same device and not a special request */ | |
e7e24500 | 568 | if (rq->rq_disk != bio->bi_bdev->bd_disk || req_no_special_merge(rq)) |
050c8ea8 TH |
569 | return false; |
570 | ||
571 | /* only merge integrity protected bio into ditto rq */ | |
572 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
573 | return false; | |
574 | ||
4363ac7c MP |
575 | /* must be using the same buffer */ |
576 | if (rq->cmd_flags & REQ_WRITE_SAME && | |
577 | !blk_write_same_mergeable(rq->bio, bio)) | |
578 | return false; | |
579 | ||
050c8ea8 TH |
580 | return true; |
581 | } | |
582 | ||
583 | int blk_try_merge(struct request *rq, struct bio *bio) | |
584 | { | |
4f024f37 | 585 | if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) |
050c8ea8 | 586 | return ELEVATOR_BACK_MERGE; |
4f024f37 | 587 | else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) |
050c8ea8 TH |
588 | return ELEVATOR_FRONT_MERGE; |
589 | return ELEVATOR_NO_MERGE; | |
590 | } |