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 | 15 | struct bio_vec bv, bvprv = { NULL }; |
05f1dd53 | 16 | int cluster, high, highprv = 1, no_sg_merge; |
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; |
05f1dd53 JA |
38 | no_sg_merge = test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags); |
39 | high = 0; | |
1e428079 | 40 | for_each_bio(bio) { |
7988613b | 41 | bio_for_each_segment(bv, bio, iter) { |
05f1dd53 JA |
42 | /* |
43 | * If SG merging is disabled, each bio vector is | |
44 | * a segment | |
45 | */ | |
46 | if (no_sg_merge) | |
47 | goto new_segment; | |
48 | ||
1e428079 JA |
49 | /* |
50 | * the trick here is making sure that a high page is | |
05f1dd53 JA |
51 | * never considered part of another segment, since |
52 | * that might change with the bounce page. | |
1e428079 | 53 | */ |
7988613b KO |
54 | high = page_to_pfn(bv.bv_page) > queue_bounce_pfn(q); |
55 | if (!high && !highprv && cluster) { | |
56 | if (seg_size + bv.bv_len | |
ae03bf63 | 57 | > queue_max_segment_size(q)) |
1e428079 | 58 | goto new_segment; |
7988613b | 59 | if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv)) |
1e428079 | 60 | goto new_segment; |
7988613b | 61 | if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv)) |
1e428079 | 62 | goto new_segment; |
d6d48196 | 63 | |
7988613b | 64 | seg_size += bv.bv_len; |
1e428079 JA |
65 | bvprv = bv; |
66 | continue; | |
67 | } | |
d6d48196 | 68 | new_segment: |
1e428079 JA |
69 | if (nr_phys_segs == 1 && seg_size > |
70 | fbio->bi_seg_front_size) | |
71 | fbio->bi_seg_front_size = seg_size; | |
86771427 | 72 | |
1e428079 JA |
73 | nr_phys_segs++; |
74 | bvprv = bv; | |
7988613b | 75 | seg_size = bv.bv_len; |
1e428079 JA |
76 | highprv = high; |
77 | } | |
59247eae | 78 | bbio = bio; |
d6d48196 JA |
79 | } |
80 | ||
59247eae JA |
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; | |
1e428079 JA |
85 | |
86 | return nr_phys_segs; | |
87 | } | |
88 | ||
89 | void blk_recalc_rq_segments(struct request *rq) | |
90 | { | |
59247eae | 91 | rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio); |
d6d48196 JA |
92 | } |
93 | ||
94 | void blk_recount_segments(struct request_queue *q, struct bio *bio) | |
95 | { | |
05f1dd53 JA |
96 | if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags)) |
97 | bio->bi_phys_segments = bio->bi_vcnt; | |
98 | else { | |
99 | struct bio *nxt = bio->bi_next; | |
100 | ||
101 | bio->bi_next = NULL; | |
102 | bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio); | |
103 | bio->bi_next = nxt; | |
104 | } | |
1e428079 | 105 | |
d6d48196 JA |
106 | bio->bi_flags |= (1 << BIO_SEG_VALID); |
107 | } | |
108 | EXPORT_SYMBOL(blk_recount_segments); | |
109 | ||
110 | static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, | |
111 | struct bio *nxt) | |
112 | { | |
2b8221e1 | 113 | struct bio_vec end_bv = { NULL }, nxt_bv; |
f619d254 KO |
114 | struct bvec_iter iter; |
115 | ||
e692cb66 | 116 | if (!blk_queue_cluster(q)) |
d6d48196 JA |
117 | return 0; |
118 | ||
86771427 | 119 | if (bio->bi_seg_back_size + nxt->bi_seg_front_size > |
ae03bf63 | 120 | queue_max_segment_size(q)) |
d6d48196 JA |
121 | return 0; |
122 | ||
e17fc0a1 DW |
123 | if (!bio_has_data(bio)) |
124 | return 1; | |
125 | ||
f619d254 KO |
126 | bio_for_each_segment(end_bv, bio, iter) |
127 | if (end_bv.bv_len == iter.bi_size) | |
128 | break; | |
129 | ||
130 | nxt_bv = bio_iovec(nxt); | |
131 | ||
132 | if (!BIOVEC_PHYS_MERGEABLE(&end_bv, &nxt_bv)) | |
e17fc0a1 DW |
133 | return 0; |
134 | ||
d6d48196 | 135 | /* |
e17fc0a1 | 136 | * bio and nxt are contiguous in memory; check if the queue allows |
d6d48196 JA |
137 | * these two to be merged into one |
138 | */ | |
f619d254 | 139 | if (BIOVEC_SEG_BOUNDARY(q, &end_bv, &nxt_bv)) |
d6d48196 JA |
140 | return 1; |
141 | ||
142 | return 0; | |
143 | } | |
144 | ||
7988613b | 145 | static inline void |
963ab9e5 | 146 | __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, |
7988613b | 147 | struct scatterlist *sglist, struct bio_vec *bvprv, |
963ab9e5 AH |
148 | struct scatterlist **sg, int *nsegs, int *cluster) |
149 | { | |
150 | ||
151 | int nbytes = bvec->bv_len; | |
152 | ||
7988613b | 153 | if (*sg && *cluster) { |
963ab9e5 AH |
154 | if ((*sg)->length + nbytes > queue_max_segment_size(q)) |
155 | goto new_segment; | |
156 | ||
7988613b | 157 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) |
963ab9e5 | 158 | goto new_segment; |
7988613b | 159 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) |
963ab9e5 AH |
160 | goto new_segment; |
161 | ||
162 | (*sg)->length += nbytes; | |
163 | } else { | |
164 | new_segment: | |
165 | if (!*sg) | |
166 | *sg = sglist; | |
167 | else { | |
168 | /* | |
169 | * If the driver previously mapped a shorter | |
170 | * list, we could see a termination bit | |
171 | * prematurely unless it fully inits the sg | |
172 | * table on each mapping. We KNOW that there | |
173 | * must be more entries here or the driver | |
174 | * would be buggy, so force clear the | |
175 | * termination bit to avoid doing a full | |
176 | * sg_init_table() in drivers for each command. | |
177 | */ | |
c8164d89 | 178 | sg_unmark_end(*sg); |
963ab9e5 AH |
179 | *sg = sg_next(*sg); |
180 | } | |
181 | ||
182 | sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); | |
183 | (*nsegs)++; | |
184 | } | |
7988613b | 185 | *bvprv = *bvec; |
963ab9e5 AH |
186 | } |
187 | ||
5cb8850c KO |
188 | static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, |
189 | struct scatterlist *sglist, | |
190 | struct scatterlist **sg) | |
d6d48196 | 191 | { |
2b8221e1 | 192 | struct bio_vec bvec, bvprv = { NULL }; |
5cb8850c | 193 | struct bvec_iter iter; |
d6d48196 JA |
194 | int nsegs, cluster; |
195 | ||
196 | nsegs = 0; | |
e692cb66 | 197 | cluster = blk_queue_cluster(q); |
d6d48196 | 198 | |
5cb8850c KO |
199 | if (bio->bi_rw & REQ_DISCARD) { |
200 | /* | |
201 | * This is a hack - drivers should be neither modifying the | |
202 | * biovec, nor relying on bi_vcnt - but because of | |
203 | * blk_add_request_payload(), a discard bio may or may not have | |
204 | * a payload we need to set up here (thank you Christoph) and | |
205 | * bi_vcnt is really the only way of telling if we need to. | |
206 | */ | |
207 | ||
208 | if (bio->bi_vcnt) | |
209 | goto single_segment; | |
210 | ||
211 | return 0; | |
212 | } | |
213 | ||
214 | if (bio->bi_rw & REQ_WRITE_SAME) { | |
215 | single_segment: | |
216 | *sg = sglist; | |
217 | bvec = bio_iovec(bio); | |
218 | sg_set_page(*sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset); | |
219 | return 1; | |
220 | } | |
221 | ||
222 | for_each_bio(bio) | |
223 | bio_for_each_segment(bvec, bio, iter) | |
224 | __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, | |
225 | &nsegs, &cluster); | |
d6d48196 | 226 | |
5cb8850c KO |
227 | return nsegs; |
228 | } | |
229 | ||
230 | /* | |
231 | * map a request to scatterlist, return number of sg entries setup. Caller | |
232 | * must make sure sg can hold rq->nr_phys_segments entries | |
233 | */ | |
234 | int blk_rq_map_sg(struct request_queue *q, struct request *rq, | |
235 | struct scatterlist *sglist) | |
236 | { | |
237 | struct scatterlist *sg = NULL; | |
238 | int nsegs = 0; | |
239 | ||
240 | if (rq->bio) | |
241 | nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); | |
f18573ab FT |
242 | |
243 | if (unlikely(rq->cmd_flags & REQ_COPY_USER) && | |
2e46e8b2 TH |
244 | (blk_rq_bytes(rq) & q->dma_pad_mask)) { |
245 | unsigned int pad_len = | |
246 | (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; | |
f18573ab FT |
247 | |
248 | sg->length += pad_len; | |
249 | rq->extra_len += pad_len; | |
250 | } | |
251 | ||
2fb98e84 | 252 | if (q->dma_drain_size && q->dma_drain_needed(rq)) { |
7b6d91da | 253 | if (rq->cmd_flags & REQ_WRITE) |
db0a2e00 TH |
254 | memset(q->dma_drain_buffer, 0, q->dma_drain_size); |
255 | ||
d6d48196 JA |
256 | sg->page_link &= ~0x02; |
257 | sg = sg_next(sg); | |
258 | sg_set_page(sg, virt_to_page(q->dma_drain_buffer), | |
259 | q->dma_drain_size, | |
260 | ((unsigned long)q->dma_drain_buffer) & | |
261 | (PAGE_SIZE - 1)); | |
262 | nsegs++; | |
7a85f889 | 263 | rq->extra_len += q->dma_drain_size; |
d6d48196 JA |
264 | } |
265 | ||
266 | if (sg) | |
267 | sg_mark_end(sg); | |
268 | ||
269 | return nsegs; | |
270 | } | |
d6d48196 JA |
271 | EXPORT_SYMBOL(blk_rq_map_sg); |
272 | ||
85b9f66a AH |
273 | /** |
274 | * blk_bio_map_sg - map a bio to a scatterlist | |
275 | * @q: request_queue in question | |
276 | * @bio: bio being mapped | |
277 | * @sglist: scatterlist being mapped | |
278 | * | |
279 | * Note: | |
280 | * Caller must make sure sg can hold bio->bi_phys_segments entries | |
281 | * | |
282 | * Will return the number of sg entries setup | |
283 | */ | |
284 | int blk_bio_map_sg(struct request_queue *q, struct bio *bio, | |
285 | struct scatterlist *sglist) | |
286 | { | |
5cb8850c KO |
287 | struct scatterlist *sg = NULL; |
288 | int nsegs; | |
289 | struct bio *next = bio->bi_next; | |
290 | bio->bi_next = NULL; | |
85b9f66a | 291 | |
5cb8850c KO |
292 | nsegs = __blk_bios_map_sg(q, bio, sglist, &sg); |
293 | bio->bi_next = next; | |
85b9f66a AH |
294 | if (sg) |
295 | sg_mark_end(sg); | |
296 | ||
297 | BUG_ON(bio->bi_phys_segments && nsegs > bio->bi_phys_segments); | |
298 | return nsegs; | |
299 | } | |
300 | EXPORT_SYMBOL(blk_bio_map_sg); | |
301 | ||
d6d48196 JA |
302 | static inline int ll_new_hw_segment(struct request_queue *q, |
303 | struct request *req, | |
304 | struct bio *bio) | |
305 | { | |
d6d48196 JA |
306 | int nr_phys_segs = bio_phys_segments(q, bio); |
307 | ||
13f05c8d MP |
308 | if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) |
309 | goto no_merge; | |
310 | ||
311 | if (bio_integrity(bio) && blk_integrity_merge_bio(q, req, bio)) | |
312 | goto no_merge; | |
d6d48196 JA |
313 | |
314 | /* | |
315 | * This will form the start of a new hw segment. Bump both | |
316 | * counters. | |
317 | */ | |
d6d48196 JA |
318 | req->nr_phys_segments += nr_phys_segs; |
319 | return 1; | |
13f05c8d MP |
320 | |
321 | no_merge: | |
322 | req->cmd_flags |= REQ_NOMERGE; | |
323 | if (req == q->last_merge) | |
324 | q->last_merge = NULL; | |
325 | return 0; | |
d6d48196 JA |
326 | } |
327 | ||
328 | int ll_back_merge_fn(struct request_queue *q, struct request *req, | |
329 | struct bio *bio) | |
330 | { | |
f31dc1cd MP |
331 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
332 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
333 | req->cmd_flags |= REQ_NOMERGE; |
334 | if (req == q->last_merge) | |
335 | q->last_merge = NULL; | |
336 | return 0; | |
337 | } | |
2cdf79ca | 338 | if (!bio_flagged(req->biotail, BIO_SEG_VALID)) |
d6d48196 | 339 | blk_recount_segments(q, req->biotail); |
2cdf79ca | 340 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 341 | blk_recount_segments(q, bio); |
d6d48196 JA |
342 | |
343 | return ll_new_hw_segment(q, req, bio); | |
344 | } | |
345 | ||
6728cb0e | 346 | int ll_front_merge_fn(struct request_queue *q, struct request *req, |
d6d48196 JA |
347 | struct bio *bio) |
348 | { | |
f31dc1cd MP |
349 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
350 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
351 | req->cmd_flags |= REQ_NOMERGE; |
352 | if (req == q->last_merge) | |
353 | q->last_merge = NULL; | |
354 | return 0; | |
355 | } | |
2cdf79ca | 356 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 357 | blk_recount_segments(q, bio); |
2cdf79ca | 358 | if (!bio_flagged(req->bio, BIO_SEG_VALID)) |
d6d48196 | 359 | blk_recount_segments(q, req->bio); |
d6d48196 JA |
360 | |
361 | return ll_new_hw_segment(q, req, bio); | |
362 | } | |
363 | ||
e7e24500 JA |
364 | /* |
365 | * blk-mq uses req->special to carry normal driver per-request payload, it | |
366 | * does not indicate a prepared command that we cannot merge with. | |
367 | */ | |
368 | static bool req_no_special_merge(struct request *req) | |
369 | { | |
370 | struct request_queue *q = req->q; | |
371 | ||
372 | return !q->mq_ops && req->special; | |
373 | } | |
374 | ||
d6d48196 JA |
375 | static int ll_merge_requests_fn(struct request_queue *q, struct request *req, |
376 | struct request *next) | |
377 | { | |
378 | int total_phys_segments; | |
86771427 FT |
379 | unsigned int seg_size = |
380 | req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; | |
d6d48196 JA |
381 | |
382 | /* | |
383 | * First check if the either of the requests are re-queued | |
384 | * requests. Can't merge them if they are. | |
385 | */ | |
e7e24500 | 386 | if (req_no_special_merge(req) || req_no_special_merge(next)) |
d6d48196 JA |
387 | return 0; |
388 | ||
389 | /* | |
390 | * Will it become too large? | |
391 | */ | |
f31dc1cd MP |
392 | if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > |
393 | blk_rq_get_max_sectors(req)) | |
d6d48196 JA |
394 | return 0; |
395 | ||
396 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
86771427 FT |
397 | if (blk_phys_contig_segment(q, req->biotail, next->bio)) { |
398 | if (req->nr_phys_segments == 1) | |
399 | req->bio->bi_seg_front_size = seg_size; | |
400 | if (next->nr_phys_segments == 1) | |
401 | next->biotail->bi_seg_back_size = seg_size; | |
d6d48196 | 402 | total_phys_segments--; |
86771427 | 403 | } |
d6d48196 | 404 | |
8a78362c | 405 | if (total_phys_segments > queue_max_segments(q)) |
d6d48196 JA |
406 | return 0; |
407 | ||
13f05c8d MP |
408 | if (blk_integrity_rq(req) && blk_integrity_merge_rq(q, req, next)) |
409 | return 0; | |
410 | ||
d6d48196 JA |
411 | /* Merge is OK... */ |
412 | req->nr_phys_segments = total_phys_segments; | |
d6d48196 JA |
413 | return 1; |
414 | } | |
415 | ||
80a761fd TH |
416 | /** |
417 | * blk_rq_set_mixed_merge - mark a request as mixed merge | |
418 | * @rq: request to mark as mixed merge | |
419 | * | |
420 | * Description: | |
421 | * @rq is about to be mixed merged. Make sure the attributes | |
422 | * which can be mixed are set in each bio and mark @rq as mixed | |
423 | * merged. | |
424 | */ | |
425 | void blk_rq_set_mixed_merge(struct request *rq) | |
426 | { | |
427 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
428 | struct bio *bio; | |
429 | ||
430 | if (rq->cmd_flags & REQ_MIXED_MERGE) | |
431 | return; | |
432 | ||
433 | /* | |
434 | * @rq will no longer represent mixable attributes for all the | |
435 | * contained bios. It will just track those of the first one. | |
436 | * Distributes the attributs to each bio. | |
437 | */ | |
438 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
439 | WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) && | |
440 | (bio->bi_rw & REQ_FAILFAST_MASK) != ff); | |
441 | bio->bi_rw |= ff; | |
442 | } | |
443 | rq->cmd_flags |= REQ_MIXED_MERGE; | |
444 | } | |
445 | ||
26308eab JM |
446 | static void blk_account_io_merge(struct request *req) |
447 | { | |
448 | if (blk_do_io_stat(req)) { | |
449 | struct hd_struct *part; | |
450 | int cpu; | |
451 | ||
452 | cpu = part_stat_lock(); | |
09e099d4 | 453 | part = req->part; |
26308eab JM |
454 | |
455 | part_round_stats(cpu, part); | |
316d315b | 456 | part_dec_in_flight(part, rq_data_dir(req)); |
26308eab | 457 | |
6c23a968 | 458 | hd_struct_put(part); |
26308eab JM |
459 | part_stat_unlock(); |
460 | } | |
461 | } | |
462 | ||
d6d48196 JA |
463 | /* |
464 | * Has to be called with the request spinlock acquired | |
465 | */ | |
466 | static int attempt_merge(struct request_queue *q, struct request *req, | |
467 | struct request *next) | |
468 | { | |
469 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
470 | return 0; | |
471 | ||
f31dc1cd MP |
472 | if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags)) |
473 | return 0; | |
474 | ||
d6d48196 JA |
475 | /* |
476 | * not contiguous | |
477 | */ | |
83096ebf | 478 | if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next)) |
d6d48196 JA |
479 | return 0; |
480 | ||
481 | if (rq_data_dir(req) != rq_data_dir(next) | |
482 | || req->rq_disk != next->rq_disk | |
e7e24500 | 483 | || req_no_special_merge(next)) |
d6d48196 JA |
484 | return 0; |
485 | ||
4363ac7c MP |
486 | if (req->cmd_flags & REQ_WRITE_SAME && |
487 | !blk_write_same_mergeable(req->bio, next->bio)) | |
488 | return 0; | |
489 | ||
d6d48196 JA |
490 | /* |
491 | * If we are allowed to merge, then append bio list | |
492 | * from next to rq and release next. merge_requests_fn | |
493 | * will have updated segment counts, update sector | |
494 | * counts here. | |
495 | */ | |
496 | if (!ll_merge_requests_fn(q, req, next)) | |
497 | return 0; | |
498 | ||
80a761fd TH |
499 | /* |
500 | * If failfast settings disagree or any of the two is already | |
501 | * a mixed merge, mark both as mixed before proceeding. This | |
502 | * makes sure that all involved bios have mixable attributes | |
503 | * set properly. | |
504 | */ | |
505 | if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE || | |
506 | (req->cmd_flags & REQ_FAILFAST_MASK) != | |
507 | (next->cmd_flags & REQ_FAILFAST_MASK)) { | |
508 | blk_rq_set_mixed_merge(req); | |
509 | blk_rq_set_mixed_merge(next); | |
510 | } | |
511 | ||
d6d48196 JA |
512 | /* |
513 | * At this point we have either done a back merge | |
514 | * or front merge. We need the smaller start_time of | |
515 | * the merged requests to be the current request | |
516 | * for accounting purposes. | |
517 | */ | |
518 | if (time_after(req->start_time, next->start_time)) | |
519 | req->start_time = next->start_time; | |
520 | ||
521 | req->biotail->bi_next = next->bio; | |
522 | req->biotail = next->biotail; | |
523 | ||
a2dec7b3 | 524 | req->__data_len += blk_rq_bytes(next); |
d6d48196 JA |
525 | |
526 | elv_merge_requests(q, req, next); | |
527 | ||
42dad764 JM |
528 | /* |
529 | * 'next' is going away, so update stats accordingly | |
530 | */ | |
531 | blk_account_io_merge(next); | |
d6d48196 JA |
532 | |
533 | req->ioprio = ioprio_best(req->ioprio, next->ioprio); | |
ab780f1e JA |
534 | if (blk_rq_cpu_valid(next)) |
535 | req->cpu = next->cpu; | |
d6d48196 | 536 | |
1cd96c24 BH |
537 | /* owner-ship of bio passed from next to req */ |
538 | next->bio = NULL; | |
d6d48196 JA |
539 | __blk_put_request(q, next); |
540 | return 1; | |
541 | } | |
542 | ||
543 | int attempt_back_merge(struct request_queue *q, struct request *rq) | |
544 | { | |
545 | struct request *next = elv_latter_request(q, rq); | |
546 | ||
547 | if (next) | |
548 | return attempt_merge(q, rq, next); | |
549 | ||
550 | return 0; | |
551 | } | |
552 | ||
553 | int attempt_front_merge(struct request_queue *q, struct request *rq) | |
554 | { | |
555 | struct request *prev = elv_former_request(q, rq); | |
556 | ||
557 | if (prev) | |
558 | return attempt_merge(q, prev, rq); | |
559 | ||
560 | return 0; | |
561 | } | |
5e84ea3a JA |
562 | |
563 | int blk_attempt_req_merge(struct request_queue *q, struct request *rq, | |
564 | struct request *next) | |
565 | { | |
566 | return attempt_merge(q, rq, next); | |
567 | } | |
050c8ea8 TH |
568 | |
569 | bool blk_rq_merge_ok(struct request *rq, struct bio *bio) | |
570 | { | |
66cb45aa JA |
571 | struct request_queue *q = rq->q; |
572 | ||
e2a60da7 | 573 | if (!rq_mergeable(rq) || !bio_mergeable(bio)) |
050c8ea8 TH |
574 | return false; |
575 | ||
f31dc1cd MP |
576 | if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw)) |
577 | return false; | |
578 | ||
050c8ea8 TH |
579 | /* different data direction or already started, don't merge */ |
580 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
581 | return false; | |
582 | ||
583 | /* must be same device and not a special request */ | |
e7e24500 | 584 | if (rq->rq_disk != bio->bi_bdev->bd_disk || req_no_special_merge(rq)) |
050c8ea8 TH |
585 | return false; |
586 | ||
587 | /* only merge integrity protected bio into ditto rq */ | |
588 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
589 | return false; | |
590 | ||
4363ac7c MP |
591 | /* must be using the same buffer */ |
592 | if (rq->cmd_flags & REQ_WRITE_SAME && | |
593 | !blk_write_same_mergeable(rq->bio, bio)) | |
594 | return false; | |
595 | ||
66cb45aa JA |
596 | if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS)) { |
597 | struct bio_vec *bprev; | |
598 | ||
599 | bprev = &rq->biotail->bi_io_vec[bio->bi_vcnt - 1]; | |
600 | if (bvec_gap_to_prev(bprev, bio->bi_io_vec[0].bv_offset)) | |
601 | return false; | |
602 | } | |
603 | ||
050c8ea8 TH |
604 | return true; |
605 | } | |
606 | ||
607 | int blk_try_merge(struct request *rq, struct bio *bio) | |
608 | { | |
4f024f37 | 609 | if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) |
050c8ea8 | 610 | return ELEVATOR_BACK_MERGE; |
4f024f37 | 611 | else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) |
050c8ea8 TH |
612 | return ELEVATOR_FRONT_MERGE; |
613 | return ELEVATOR_NO_MERGE; | |
614 | } |