Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
d6d48196 JA |
2 | /* |
3 | * Functions related to segment and merge handling | |
4 | */ | |
5 | #include <linux/kernel.h> | |
6 | #include <linux/module.h> | |
7 | #include <linux/bio.h> | |
8 | #include <linux/blkdev.h> | |
fe45e630 | 9 | #include <linux/blk-integrity.h> |
d6d48196 JA |
10 | #include <linux/scatterlist.h> |
11 | ||
cda22646 MK |
12 | #include <trace/events/block.h> |
13 | ||
d6d48196 | 14 | #include "blk.h" |
8e756373 | 15 | #include "blk-rq-qos.h" |
a7b36ee6 | 16 | #include "blk-throttle.h" |
d6d48196 | 17 | |
ff18d77b CH |
18 | static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv) |
19 | { | |
20 | *bv = mp_bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); | |
21 | } | |
22 | ||
23 | static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv) | |
24 | { | |
25 | struct bvec_iter iter = bio->bi_iter; | |
26 | int idx; | |
27 | ||
28 | bio_get_first_bvec(bio, bv); | |
29 | if (bv->bv_len == bio->bi_iter.bi_size) | |
30 | return; /* this bio only has a single bvec */ | |
31 | ||
32 | bio_advance_iter(bio, &iter, iter.bi_size); | |
33 | ||
34 | if (!iter.bi_bvec_done) | |
35 | idx = iter.bi_idx - 1; | |
36 | else /* in the middle of bvec */ | |
37 | idx = iter.bi_idx; | |
38 | ||
39 | *bv = bio->bi_io_vec[idx]; | |
40 | ||
41 | /* | |
42 | * iter.bi_bvec_done records actual length of the last bvec | |
43 | * if this bio ends in the middle of one io vector | |
44 | */ | |
45 | if (iter.bi_bvec_done) | |
46 | bv->bv_len = iter.bi_bvec_done; | |
47 | } | |
48 | ||
e9907009 CH |
49 | static inline bool bio_will_gap(struct request_queue *q, |
50 | struct request *prev_rq, struct bio *prev, struct bio *next) | |
51 | { | |
52 | struct bio_vec pb, nb; | |
53 | ||
54 | if (!bio_has_data(prev) || !queue_virt_boundary(q)) | |
55 | return false; | |
56 | ||
57 | /* | |
58 | * Don't merge if the 1st bio starts with non-zero offset, otherwise it | |
59 | * is quite difficult to respect the sg gap limit. We work hard to | |
60 | * merge a huge number of small single bios in case of mkfs. | |
61 | */ | |
62 | if (prev_rq) | |
63 | bio_get_first_bvec(prev_rq->bio, &pb); | |
64 | else | |
65 | bio_get_first_bvec(prev, &pb); | |
df376b2e | 66 | if (pb.bv_offset & queue_virt_boundary(q)) |
e9907009 CH |
67 | return true; |
68 | ||
69 | /* | |
70 | * We don't need to worry about the situation that the merged segment | |
71 | * ends in unaligned virt boundary: | |
72 | * | |
73 | * - if 'pb' ends aligned, the merged segment ends aligned | |
74 | * - if 'pb' ends unaligned, the next bio must include | |
75 | * one single bvec of 'nb', otherwise the 'nb' can't | |
76 | * merge with 'pb' | |
77 | */ | |
78 | bio_get_last_bvec(prev, &pb); | |
79 | bio_get_first_bvec(next, &nb); | |
200a9aff | 80 | if (biovec_phys_mergeable(q, &pb, &nb)) |
e9907009 CH |
81 | return false; |
82 | return __bvec_gap_to_prev(q, &pb, nb.bv_offset); | |
83 | } | |
84 | ||
85 | static inline bool req_gap_back_merge(struct request *req, struct bio *bio) | |
86 | { | |
87 | return bio_will_gap(req->q, req, req->biotail, bio); | |
88 | } | |
89 | ||
90 | static inline bool req_gap_front_merge(struct request *req, struct bio *bio) | |
91 | { | |
92 | return bio_will_gap(req->q, NULL, bio, req->bio); | |
93 | } | |
94 | ||
54efd50b KO |
95 | static struct bio *blk_bio_discard_split(struct request_queue *q, |
96 | struct bio *bio, | |
bdced438 ML |
97 | struct bio_set *bs, |
98 | unsigned *nsegs) | |
54efd50b KO |
99 | { |
100 | unsigned int max_discard_sectors, granularity; | |
101 | int alignment; | |
102 | sector_t tmp; | |
103 | unsigned split_sectors; | |
104 | ||
bdced438 ML |
105 | *nsegs = 1; |
106 | ||
54efd50b KO |
107 | /* Zero-sector (unknown) and one-sector granularities are the same. */ |
108 | granularity = max(q->limits.discard_granularity >> 9, 1U); | |
109 | ||
1adfc5e4 ML |
110 | max_discard_sectors = min(q->limits.max_discard_sectors, |
111 | bio_allowed_max_sectors(q)); | |
54efd50b KO |
112 | max_discard_sectors -= max_discard_sectors % granularity; |
113 | ||
114 | if (unlikely(!max_discard_sectors)) { | |
115 | /* XXX: warn */ | |
116 | return NULL; | |
117 | } | |
118 | ||
119 | if (bio_sectors(bio) <= max_discard_sectors) | |
120 | return NULL; | |
121 | ||
122 | split_sectors = max_discard_sectors; | |
123 | ||
124 | /* | |
125 | * If the next starting sector would be misaligned, stop the discard at | |
126 | * the previous aligned sector. | |
127 | */ | |
128 | alignment = (q->limits.discard_alignment >> 9) % granularity; | |
129 | ||
130 | tmp = bio->bi_iter.bi_sector + split_sectors - alignment; | |
131 | tmp = sector_div(tmp, granularity); | |
132 | ||
133 | if (split_sectors > tmp) | |
134 | split_sectors -= tmp; | |
135 | ||
136 | return bio_split(bio, split_sectors, GFP_NOIO, bs); | |
137 | } | |
138 | ||
885fa13f CH |
139 | static struct bio *blk_bio_write_zeroes_split(struct request_queue *q, |
140 | struct bio *bio, struct bio_set *bs, unsigned *nsegs) | |
141 | { | |
d665e12a | 142 | *nsegs = 0; |
885fa13f CH |
143 | |
144 | if (!q->limits.max_write_zeroes_sectors) | |
145 | return NULL; | |
146 | ||
147 | if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors) | |
148 | return NULL; | |
149 | ||
150 | return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs); | |
151 | } | |
152 | ||
54efd50b KO |
153 | static struct bio *blk_bio_write_same_split(struct request_queue *q, |
154 | struct bio *bio, | |
bdced438 ML |
155 | struct bio_set *bs, |
156 | unsigned *nsegs) | |
54efd50b | 157 | { |
bdced438 ML |
158 | *nsegs = 1; |
159 | ||
54efd50b KO |
160 | if (!q->limits.max_write_same_sectors) |
161 | return NULL; | |
162 | ||
163 | if (bio_sectors(bio) <= q->limits.max_write_same_sectors) | |
164 | return NULL; | |
165 | ||
166 | return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); | |
167 | } | |
168 | ||
9cc5169c BVA |
169 | /* |
170 | * Return the maximum number of sectors from the start of a bio that may be | |
171 | * submitted as a single request to a block device. If enough sectors remain, | |
172 | * align the end to the physical block size. Otherwise align the end to the | |
173 | * logical block size. This approach minimizes the number of non-aligned | |
174 | * requests that are submitted to a block device if the start of a bio is not | |
175 | * aligned to a physical block boundary. | |
176 | */ | |
d0e5fbb0 ML |
177 | static inline unsigned get_max_io_size(struct request_queue *q, |
178 | struct bio *bio) | |
179 | { | |
3ee16db3 | 180 | unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector, 0); |
9cc5169c BVA |
181 | unsigned max_sectors = sectors; |
182 | unsigned pbs = queue_physical_block_size(q) >> SECTOR_SHIFT; | |
183 | unsigned lbs = queue_logical_block_size(q) >> SECTOR_SHIFT; | |
184 | unsigned start_offset = bio->bi_iter.bi_sector & (pbs - 1); | |
d0e5fbb0 | 185 | |
9cc5169c BVA |
186 | max_sectors += start_offset; |
187 | max_sectors &= ~(pbs - 1); | |
188 | if (max_sectors > start_offset) | |
189 | return max_sectors - start_offset; | |
d0e5fbb0 | 190 | |
e4b469c6 | 191 | return sectors & ~(lbs - 1); |
d0e5fbb0 ML |
192 | } |
193 | ||
429120f3 ML |
194 | static inline unsigned get_max_segment_size(const struct request_queue *q, |
195 | struct page *start_page, | |
196 | unsigned long offset) | |
dcebd755 ML |
197 | { |
198 | unsigned long mask = queue_segment_boundary(q); | |
199 | ||
429120f3 | 200 | offset = mask & (page_to_phys(start_page) + offset); |
4a2f704e ML |
201 | |
202 | /* | |
203 | * overflow may be triggered in case of zero page physical address | |
204 | * on 32bit arch, use queue's max segment size when that happens. | |
205 | */ | |
206 | return min_not_zero(mask - offset + 1, | |
207 | (unsigned long)queue_max_segment_size(q)); | |
dcebd755 ML |
208 | } |
209 | ||
708b25b3 BVA |
210 | /** |
211 | * bvec_split_segs - verify whether or not a bvec should be split in the middle | |
212 | * @q: [in] request queue associated with the bio associated with @bv | |
213 | * @bv: [in] bvec to examine | |
214 | * @nsegs: [in,out] Number of segments in the bio being built. Incremented | |
215 | * by the number of segments from @bv that may be appended to that | |
216 | * bio without exceeding @max_segs | |
217 | * @sectors: [in,out] Number of sectors in the bio being built. Incremented | |
218 | * by the number of sectors from @bv that may be appended to that | |
219 | * bio without exceeding @max_sectors | |
220 | * @max_segs: [in] upper bound for *@nsegs | |
221 | * @max_sectors: [in] upper bound for *@sectors | |
222 | * | |
223 | * When splitting a bio, it can happen that a bvec is encountered that is too | |
224 | * big to fit in a single segment and hence that it has to be split in the | |
225 | * middle. This function verifies whether or not that should happen. The value | |
226 | * %true is returned if and only if appending the entire @bv to a bio with | |
227 | * *@nsegs segments and *@sectors sectors would make that bio unacceptable for | |
228 | * the block driver. | |
dcebd755 | 229 | */ |
af2c68fe BVA |
230 | static bool bvec_split_segs(const struct request_queue *q, |
231 | const struct bio_vec *bv, unsigned *nsegs, | |
708b25b3 BVA |
232 | unsigned *sectors, unsigned max_segs, |
233 | unsigned max_sectors) | |
dcebd755 | 234 | { |
708b25b3 BVA |
235 | unsigned max_len = (min(max_sectors, UINT_MAX >> 9) - *sectors) << 9; |
236 | unsigned len = min(bv->bv_len, max_len); | |
dcebd755 | 237 | unsigned total_len = 0; |
ff9811b3 | 238 | unsigned seg_size = 0; |
dcebd755 | 239 | |
ff9811b3 | 240 | while (len && *nsegs < max_segs) { |
429120f3 ML |
241 | seg_size = get_max_segment_size(q, bv->bv_page, |
242 | bv->bv_offset + total_len); | |
dcebd755 ML |
243 | seg_size = min(seg_size, len); |
244 | ||
ff9811b3 | 245 | (*nsegs)++; |
dcebd755 ML |
246 | total_len += seg_size; |
247 | len -= seg_size; | |
248 | ||
249 | if ((bv->bv_offset + total_len) & queue_virt_boundary(q)) | |
250 | break; | |
251 | } | |
252 | ||
ff9811b3 | 253 | *sectors += total_len >> 9; |
dcebd755 | 254 | |
708b25b3 BVA |
255 | /* tell the caller to split the bvec if it is too big to fit */ |
256 | return len > 0 || bv->bv_len > max_len; | |
dcebd755 ML |
257 | } |
258 | ||
dad77584 BVA |
259 | /** |
260 | * blk_bio_segment_split - split a bio in two bios | |
261 | * @q: [in] request queue pointer | |
262 | * @bio: [in] bio to be split | |
263 | * @bs: [in] bio set to allocate the clone from | |
264 | * @segs: [out] number of segments in the bio with the first half of the sectors | |
265 | * | |
266 | * Clone @bio, update the bi_iter of the clone to represent the first sectors | |
267 | * of @bio and update @bio->bi_iter to represent the remaining sectors. The | |
268 | * following is guaranteed for the cloned bio: | |
269 | * - That it has at most get_max_io_size(@q, @bio) sectors. | |
270 | * - That it has at most queue_max_segments(@q) segments. | |
271 | * | |
272 | * Except for discard requests the cloned bio will point at the bi_io_vec of | |
273 | * the original bio. It is the responsibility of the caller to ensure that the | |
274 | * original bio is not freed before the cloned bio. The caller is also | |
275 | * responsible for ensuring that @bs is only destroyed after processing of the | |
276 | * split bio has finished. | |
277 | */ | |
54efd50b KO |
278 | static struct bio *blk_bio_segment_split(struct request_queue *q, |
279 | struct bio *bio, | |
bdced438 ML |
280 | struct bio_set *bs, |
281 | unsigned *segs) | |
54efd50b | 282 | { |
5014c311 | 283 | struct bio_vec bv, bvprv, *bvprvp = NULL; |
54efd50b | 284 | struct bvec_iter iter; |
6869875f | 285 | unsigned nsegs = 0, sectors = 0; |
d0e5fbb0 | 286 | const unsigned max_sectors = get_max_io_size(q, bio); |
05b700ba | 287 | const unsigned max_segs = queue_max_segments(q); |
54efd50b | 288 | |
dcebd755 | 289 | bio_for_each_bvec(bv, bio, iter) { |
54efd50b KO |
290 | /* |
291 | * If the queue doesn't support SG gaps and adding this | |
292 | * offset would create a gap, disallow it. | |
293 | */ | |
5014c311 | 294 | if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) |
54efd50b KO |
295 | goto split; |
296 | ||
708b25b3 BVA |
297 | if (nsegs < max_segs && |
298 | sectors + (bv.bv_len >> 9) <= max_sectors && | |
299 | bv.bv_offset + bv.bv_len <= PAGE_SIZE) { | |
300 | nsegs++; | |
301 | sectors += bv.bv_len >> 9; | |
302 | } else if (bvec_split_segs(q, &bv, &nsegs, §ors, max_segs, | |
303 | max_sectors)) { | |
cf8c0c6a | 304 | goto split; |
e36f6204 KB |
305 | } |
306 | ||
54efd50b | 307 | bvprv = bv; |
578270bf | 308 | bvprvp = &bvprv; |
54efd50b KO |
309 | } |
310 | ||
d627065d CH |
311 | *segs = nsegs; |
312 | return NULL; | |
54efd50b | 313 | split: |
bdced438 | 314 | *segs = nsegs; |
cc29e1bf JX |
315 | |
316 | /* | |
317 | * Bio splitting may cause subtle trouble such as hang when doing sync | |
318 | * iopoll in direct IO routine. Given performance gain of iopoll for | |
319 | * big IO can be trival, disable iopoll when split needed. | |
320 | */ | |
6ce913fe | 321 | bio_clear_polled(bio); |
d627065d | 322 | return bio_split(bio, sectors, GFP_NOIO, bs); |
54efd50b KO |
323 | } |
324 | ||
dad77584 BVA |
325 | /** |
326 | * __blk_queue_split - split a bio and submit the second half | |
abd45c15 | 327 | * @q: [in] request_queue new bio is being queued at |
dad77584 BVA |
328 | * @bio: [in, out] bio to be split |
329 | * @nr_segs: [out] number of segments in the first bio | |
330 | * | |
331 | * Split a bio into two bios, chain the two bios, submit the second half and | |
332 | * store a pointer to the first half in *@bio. If the second bio is still too | |
333 | * big it will be split by a recursive call to this function. Since this | |
309dca30 CH |
334 | * function may allocate a new bio from q->bio_split, it is the responsibility |
335 | * of the caller to ensure that q->bio_split is only released after processing | |
336 | * of the split bio has finished. | |
dad77584 | 337 | */ |
abd45c15 JA |
338 | void __blk_queue_split(struct request_queue *q, struct bio **bio, |
339 | unsigned int *nr_segs) | |
54efd50b | 340 | { |
fa532287 | 341 | struct bio *split = NULL; |
54efd50b | 342 | |
7afafc8a AH |
343 | switch (bio_op(*bio)) { |
344 | case REQ_OP_DISCARD: | |
345 | case REQ_OP_SECURE_ERASE: | |
14ccb66b | 346 | split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs); |
7afafc8a | 347 | break; |
a6f0788e | 348 | case REQ_OP_WRITE_ZEROES: |
14ccb66b CH |
349 | split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split, |
350 | nr_segs); | |
a6f0788e | 351 | break; |
7afafc8a | 352 | case REQ_OP_WRITE_SAME: |
14ccb66b CH |
353 | split = blk_bio_write_same_split(q, *bio, &q->bio_split, |
354 | nr_segs); | |
7afafc8a AH |
355 | break; |
356 | default: | |
14ccb66b | 357 | split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs); |
7afafc8a AH |
358 | break; |
359 | } | |
bdced438 | 360 | |
54efd50b | 361 | if (split) { |
6ac45aeb | 362 | /* there isn't chance to merge the splitted bio */ |
1eff9d32 | 363 | split->bi_opf |= REQ_NOMERGE; |
6ac45aeb | 364 | |
54efd50b | 365 | bio_chain(split, *bio); |
eb6f7f7c | 366 | trace_block_split(split, (*bio)->bi_iter.bi_sector); |
ed00aabd | 367 | submit_bio_noacct(*bio); |
54efd50b | 368 | *bio = split; |
4f1e9630 CX |
369 | |
370 | blk_throtl_charge_bio_split(*bio); | |
54efd50b KO |
371 | } |
372 | } | |
14ccb66b | 373 | |
dad77584 BVA |
374 | /** |
375 | * blk_queue_split - split a bio and submit the second half | |
dad77584 BVA |
376 | * @bio: [in, out] bio to be split |
377 | * | |
378 | * Split a bio into two bios, chains the two bios, submit the second half and | |
379 | * store a pointer to the first half in *@bio. Since this function may allocate | |
309dca30 CH |
380 | * a new bio from q->bio_split, it is the responsibility of the caller to ensure |
381 | * that q->bio_split is only released after processing of the split bio has | |
382 | * finished. | |
dad77584 | 383 | */ |
f695ca38 | 384 | void blk_queue_split(struct bio **bio) |
14ccb66b | 385 | { |
859897c3 | 386 | struct request_queue *q = bdev_get_queue((*bio)->bi_bdev); |
14ccb66b CH |
387 | unsigned int nr_segs; |
388 | ||
abd45c15 JA |
389 | if (blk_may_split(q, *bio)) |
390 | __blk_queue_split(q, bio, &nr_segs); | |
14ccb66b | 391 | } |
54efd50b KO |
392 | EXPORT_SYMBOL(blk_queue_split); |
393 | ||
e9cd19c0 | 394 | unsigned int blk_recalc_rq_segments(struct request *rq) |
d6d48196 | 395 | { |
6869875f | 396 | unsigned int nr_phys_segs = 0; |
ff9811b3 | 397 | unsigned int nr_sectors = 0; |
e9cd19c0 | 398 | struct req_iterator iter; |
6869875f | 399 | struct bio_vec bv; |
d6d48196 | 400 | |
e9cd19c0 | 401 | if (!rq->bio) |
1e428079 | 402 | return 0; |
d6d48196 | 403 | |
e9cd19c0 | 404 | switch (bio_op(rq->bio)) { |
a6f0788e CK |
405 | case REQ_OP_DISCARD: |
406 | case REQ_OP_SECURE_ERASE: | |
a958937f DJ |
407 | if (queue_max_discard_segments(rq->q) > 1) { |
408 | struct bio *bio = rq->bio; | |
409 | ||
410 | for_each_bio(bio) | |
411 | nr_phys_segs++; | |
412 | return nr_phys_segs; | |
413 | } | |
414 | return 1; | |
a6f0788e | 415 | case REQ_OP_WRITE_ZEROES: |
f9d03f96 CH |
416 | return 0; |
417 | case REQ_OP_WRITE_SAME: | |
5cb8850c | 418 | return 1; |
a6f0788e | 419 | } |
5cb8850c | 420 | |
e9cd19c0 | 421 | rq_for_each_bvec(bv, rq, iter) |
ff9811b3 | 422 | bvec_split_segs(rq->q, &bv, &nr_phys_segs, &nr_sectors, |
708b25b3 | 423 | UINT_MAX, UINT_MAX); |
1e428079 JA |
424 | return nr_phys_segs; |
425 | } | |
426 | ||
48d7727c | 427 | static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, |
862e5a5e ML |
428 | struct scatterlist *sglist) |
429 | { | |
430 | if (!*sg) | |
431 | return sglist; | |
432 | ||
433 | /* | |
434 | * If the driver previously mapped a shorter list, we could see a | |
435 | * termination bit prematurely unless it fully inits the sg table | |
436 | * on each mapping. We KNOW that there must be more entries here | |
437 | * or the driver would be buggy, so force clear the termination bit | |
438 | * to avoid doing a full sg_init_table() in drivers for each command. | |
439 | */ | |
440 | sg_unmark_end(*sg); | |
441 | return sg_next(*sg); | |
442 | } | |
443 | ||
444 | static unsigned blk_bvec_map_sg(struct request_queue *q, | |
445 | struct bio_vec *bvec, struct scatterlist *sglist, | |
446 | struct scatterlist **sg) | |
447 | { | |
448 | unsigned nbytes = bvec->bv_len; | |
8a96a0e4 | 449 | unsigned nsegs = 0, total = 0; |
862e5a5e ML |
450 | |
451 | while (nbytes > 0) { | |
8a96a0e4 | 452 | unsigned offset = bvec->bv_offset + total; |
429120f3 ML |
453 | unsigned len = min(get_max_segment_size(q, bvec->bv_page, |
454 | offset), nbytes); | |
f9f76879 CH |
455 | struct page *page = bvec->bv_page; |
456 | ||
457 | /* | |
458 | * Unfortunately a fair number of drivers barf on scatterlists | |
459 | * that have an offset larger than PAGE_SIZE, despite other | |
460 | * subsystems dealing with that invariant just fine. For now | |
461 | * stick to the legacy format where we never present those from | |
462 | * the block layer, but the code below should be removed once | |
463 | * these offenders (mostly MMC/SD drivers) are fixed. | |
464 | */ | |
465 | page += (offset >> PAGE_SHIFT); | |
466 | offset &= ~PAGE_MASK; | |
862e5a5e ML |
467 | |
468 | *sg = blk_next_sg(sg, sglist); | |
f9f76879 | 469 | sg_set_page(*sg, page, len, offset); |
862e5a5e | 470 | |
8a96a0e4 CH |
471 | total += len; |
472 | nbytes -= len; | |
862e5a5e ML |
473 | nsegs++; |
474 | } | |
475 | ||
476 | return nsegs; | |
477 | } | |
478 | ||
16e3e418 ML |
479 | static inline int __blk_bvec_map_sg(struct bio_vec bv, |
480 | struct scatterlist *sglist, struct scatterlist **sg) | |
481 | { | |
482 | *sg = blk_next_sg(sg, sglist); | |
483 | sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); | |
484 | return 1; | |
485 | } | |
486 | ||
f6970f83 ML |
487 | /* only try to merge bvecs into one sg if they are from two bios */ |
488 | static inline bool | |
489 | __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec, | |
490 | struct bio_vec *bvprv, struct scatterlist **sg) | |
963ab9e5 AH |
491 | { |
492 | ||
493 | int nbytes = bvec->bv_len; | |
494 | ||
f6970f83 ML |
495 | if (!*sg) |
496 | return false; | |
963ab9e5 | 497 | |
f6970f83 ML |
498 | if ((*sg)->length + nbytes > queue_max_segment_size(q)) |
499 | return false; | |
500 | ||
501 | if (!biovec_phys_mergeable(q, bvprv, bvec)) | |
502 | return false; | |
503 | ||
504 | (*sg)->length += nbytes; | |
505 | ||
506 | return true; | |
963ab9e5 AH |
507 | } |
508 | ||
5cb8850c KO |
509 | static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, |
510 | struct scatterlist *sglist, | |
511 | struct scatterlist **sg) | |
d6d48196 | 512 | { |
3f649ab7 | 513 | struct bio_vec bvec, bvprv = { NULL }; |
5cb8850c | 514 | struct bvec_iter iter; |
38417468 | 515 | int nsegs = 0; |
f6970f83 | 516 | bool new_bio = false; |
5cb8850c | 517 | |
f6970f83 ML |
518 | for_each_bio(bio) { |
519 | bio_for_each_bvec(bvec, bio, iter) { | |
520 | /* | |
521 | * Only try to merge bvecs from two bios given we | |
522 | * have done bio internal merge when adding pages | |
523 | * to bio | |
524 | */ | |
525 | if (new_bio && | |
526 | __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg)) | |
527 | goto next_bvec; | |
528 | ||
529 | if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE) | |
530 | nsegs += __blk_bvec_map_sg(bvec, sglist, sg); | |
531 | else | |
532 | nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg); | |
533 | next_bvec: | |
534 | new_bio = false; | |
535 | } | |
b21e11c5 ML |
536 | if (likely(bio->bi_iter.bi_size)) { |
537 | bvprv = bvec; | |
538 | new_bio = true; | |
539 | } | |
f6970f83 | 540 | } |
d6d48196 | 541 | |
5cb8850c KO |
542 | return nsegs; |
543 | } | |
544 | ||
545 | /* | |
546 | * map a request to scatterlist, return number of sg entries setup. Caller | |
547 | * must make sure sg can hold rq->nr_phys_segments entries | |
548 | */ | |
89de1504 CH |
549 | int __blk_rq_map_sg(struct request_queue *q, struct request *rq, |
550 | struct scatterlist *sglist, struct scatterlist **last_sg) | |
5cb8850c | 551 | { |
5cb8850c KO |
552 | int nsegs = 0; |
553 | ||
f9d03f96 | 554 | if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) |
89de1504 | 555 | nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, last_sg); |
f9d03f96 | 556 | else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME) |
89de1504 | 557 | nsegs = __blk_bvec_map_sg(bio_iovec(rq->bio), sglist, last_sg); |
f9d03f96 | 558 | else if (rq->bio) |
89de1504 | 559 | nsegs = __blk_bios_map_sg(q, rq->bio, sglist, last_sg); |
f18573ab | 560 | |
89de1504 CH |
561 | if (*last_sg) |
562 | sg_mark_end(*last_sg); | |
d6d48196 | 563 | |
12e57f59 ML |
564 | /* |
565 | * Something must have been wrong if the figured number of | |
566 | * segment is bigger than number of req's physical segments | |
567 | */ | |
f9d03f96 | 568 | WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); |
12e57f59 | 569 | |
d6d48196 JA |
570 | return nsegs; |
571 | } | |
89de1504 | 572 | EXPORT_SYMBOL(__blk_rq_map_sg); |
d6d48196 | 573 | |
943b40c8 ML |
574 | static inline unsigned int blk_rq_get_max_segments(struct request *rq) |
575 | { | |
576 | if (req_op(rq) == REQ_OP_DISCARD) | |
577 | return queue_max_discard_segments(rq->q); | |
578 | return queue_max_segments(rq->q); | |
579 | } | |
580 | ||
badf7f64 CH |
581 | static inline unsigned int blk_rq_get_max_sectors(struct request *rq, |
582 | sector_t offset) | |
583 | { | |
584 | struct request_queue *q = rq->q; | |
585 | ||
586 | if (blk_rq_is_passthrough(rq)) | |
587 | return q->limits.max_hw_sectors; | |
588 | ||
589 | if (!q->limits.chunk_sectors || | |
590 | req_op(rq) == REQ_OP_DISCARD || | |
591 | req_op(rq) == REQ_OP_SECURE_ERASE) | |
592 | return blk_queue_get_max_sectors(q, req_op(rq)); | |
593 | ||
594 | return min(blk_max_size_offset(q, offset, 0), | |
595 | blk_queue_get_max_sectors(q, req_op(rq))); | |
596 | } | |
597 | ||
14ccb66b CH |
598 | static inline int ll_new_hw_segment(struct request *req, struct bio *bio, |
599 | unsigned int nr_phys_segs) | |
d6d48196 | 600 | { |
2705dfb2 | 601 | if (blk_integrity_merge_bio(req->q, req, bio) == false) |
13f05c8d MP |
602 | goto no_merge; |
603 | ||
2705dfb2 ML |
604 | /* discard request merge won't add new segment */ |
605 | if (req_op(req) == REQ_OP_DISCARD) | |
606 | return 1; | |
607 | ||
608 | if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) | |
13f05c8d | 609 | goto no_merge; |
d6d48196 JA |
610 | |
611 | /* | |
612 | * This will form the start of a new hw segment. Bump both | |
613 | * counters. | |
614 | */ | |
d6d48196 JA |
615 | req->nr_phys_segments += nr_phys_segs; |
616 | return 1; | |
13f05c8d MP |
617 | |
618 | no_merge: | |
14ccb66b | 619 | req_set_nomerge(req->q, req); |
13f05c8d | 620 | return 0; |
d6d48196 JA |
621 | } |
622 | ||
14ccb66b | 623 | int ll_back_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs) |
d6d48196 | 624 | { |
5e7c4274 JA |
625 | if (req_gap_back_merge(req, bio)) |
626 | return 0; | |
7f39add3 SG |
627 | if (blk_integrity_rq(req) && |
628 | integrity_req_gap_back_merge(req, bio)) | |
629 | return 0; | |
a892c8d5 ST |
630 | if (!bio_crypt_ctx_back_mergeable(req, bio)) |
631 | return 0; | |
f31dc1cd | 632 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
17007f39 | 633 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) { |
14ccb66b | 634 | req_set_nomerge(req->q, req); |
d6d48196 JA |
635 | return 0; |
636 | } | |
d6d48196 | 637 | |
14ccb66b | 638 | return ll_new_hw_segment(req, bio, nr_segs); |
d6d48196 JA |
639 | } |
640 | ||
eda5cc99 CH |
641 | static int ll_front_merge_fn(struct request *req, struct bio *bio, |
642 | unsigned int nr_segs) | |
d6d48196 | 643 | { |
5e7c4274 JA |
644 | if (req_gap_front_merge(req, bio)) |
645 | return 0; | |
7f39add3 SG |
646 | if (blk_integrity_rq(req) && |
647 | integrity_req_gap_front_merge(req, bio)) | |
648 | return 0; | |
a892c8d5 ST |
649 | if (!bio_crypt_ctx_front_mergeable(req, bio)) |
650 | return 0; | |
f31dc1cd | 651 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
17007f39 | 652 | blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { |
14ccb66b | 653 | req_set_nomerge(req->q, req); |
d6d48196 JA |
654 | return 0; |
655 | } | |
d6d48196 | 656 | |
14ccb66b | 657 | return ll_new_hw_segment(req, bio, nr_segs); |
d6d48196 JA |
658 | } |
659 | ||
445251d0 JA |
660 | static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, |
661 | struct request *next) | |
662 | { | |
663 | unsigned short segments = blk_rq_nr_discard_segments(req); | |
664 | ||
665 | if (segments >= queue_max_discard_segments(q)) | |
666 | goto no_merge; | |
667 | if (blk_rq_sectors(req) + bio_sectors(next->bio) > | |
668 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) | |
669 | goto no_merge; | |
670 | ||
671 | req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); | |
672 | return true; | |
673 | no_merge: | |
674 | req_set_nomerge(q, req); | |
675 | return false; | |
676 | } | |
677 | ||
d6d48196 JA |
678 | static int ll_merge_requests_fn(struct request_queue *q, struct request *req, |
679 | struct request *next) | |
680 | { | |
681 | int total_phys_segments; | |
d6d48196 | 682 | |
5e7c4274 | 683 | if (req_gap_back_merge(req, next->bio)) |
854fbb9c KB |
684 | return 0; |
685 | ||
d6d48196 JA |
686 | /* |
687 | * Will it become too large? | |
688 | */ | |
f31dc1cd | 689 | if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > |
17007f39 | 690 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) |
d6d48196 JA |
691 | return 0; |
692 | ||
693 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
943b40c8 | 694 | if (total_phys_segments > blk_rq_get_max_segments(req)) |
d6d48196 JA |
695 | return 0; |
696 | ||
4eaf99be | 697 | if (blk_integrity_merge_rq(q, req, next) == false) |
13f05c8d MP |
698 | return 0; |
699 | ||
a892c8d5 ST |
700 | if (!bio_crypt_ctx_merge_rq(req, next)) |
701 | return 0; | |
702 | ||
d6d48196 JA |
703 | /* Merge is OK... */ |
704 | req->nr_phys_segments = total_phys_segments; | |
d6d48196 JA |
705 | return 1; |
706 | } | |
707 | ||
80a761fd TH |
708 | /** |
709 | * blk_rq_set_mixed_merge - mark a request as mixed merge | |
710 | * @rq: request to mark as mixed merge | |
711 | * | |
712 | * Description: | |
713 | * @rq is about to be mixed merged. Make sure the attributes | |
714 | * which can be mixed are set in each bio and mark @rq as mixed | |
715 | * merged. | |
716 | */ | |
717 | void blk_rq_set_mixed_merge(struct request *rq) | |
718 | { | |
719 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
720 | struct bio *bio; | |
721 | ||
e8064021 | 722 | if (rq->rq_flags & RQF_MIXED_MERGE) |
80a761fd TH |
723 | return; |
724 | ||
725 | /* | |
726 | * @rq will no longer represent mixable attributes for all the | |
727 | * contained bios. It will just track those of the first one. | |
728 | * Distributes the attributs to each bio. | |
729 | */ | |
730 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
1eff9d32 JA |
731 | WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && |
732 | (bio->bi_opf & REQ_FAILFAST_MASK) != ff); | |
733 | bio->bi_opf |= ff; | |
80a761fd | 734 | } |
e8064021 | 735 | rq->rq_flags |= RQF_MIXED_MERGE; |
80a761fd TH |
736 | } |
737 | ||
b9c54f56 | 738 | static void blk_account_io_merge_request(struct request *req) |
26308eab JM |
739 | { |
740 | if (blk_do_io_stat(req)) { | |
112f158f | 741 | part_stat_lock(); |
b9c54f56 | 742 | part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); |
26308eab JM |
743 | part_stat_unlock(); |
744 | } | |
745 | } | |
b9c54f56 | 746 | |
e96c0d83 EB |
747 | static enum elv_merge blk_try_req_merge(struct request *req, |
748 | struct request *next) | |
69840466 JW |
749 | { |
750 | if (blk_discard_mergable(req)) | |
751 | return ELEVATOR_DISCARD_MERGE; | |
752 | else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) | |
753 | return ELEVATOR_BACK_MERGE; | |
754 | ||
755 | return ELEVATOR_NO_MERGE; | |
756 | } | |
26308eab | 757 | |
badf7f64 CH |
758 | static inline bool blk_write_same_mergeable(struct bio *a, struct bio *b) |
759 | { | |
760 | if (bio_page(a) == bio_page(b) && bio_offset(a) == bio_offset(b)) | |
761 | return true; | |
762 | return false; | |
763 | } | |
764 | ||
d6d48196 | 765 | /* |
b973cb7e JA |
766 | * For non-mq, this has to be called with the request spinlock acquired. |
767 | * For mq with scheduling, the appropriate queue wide lock should be held. | |
d6d48196 | 768 | */ |
b973cb7e JA |
769 | static struct request *attempt_merge(struct request_queue *q, |
770 | struct request *req, struct request *next) | |
d6d48196 JA |
771 | { |
772 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
b973cb7e | 773 | return NULL; |
d6d48196 | 774 | |
288dab8a | 775 | if (req_op(req) != req_op(next)) |
b973cb7e | 776 | return NULL; |
f31dc1cd | 777 | |
d6d48196 | 778 | if (rq_data_dir(req) != rq_data_dir(next) |
2081a56b | 779 | || req->rq_disk != next->rq_disk) |
b973cb7e | 780 | return NULL; |
d6d48196 | 781 | |
8fe0d473 | 782 | if (req_op(req) == REQ_OP_WRITE_SAME && |
4363ac7c | 783 | !blk_write_same_mergeable(req->bio, next->bio)) |
b973cb7e | 784 | return NULL; |
4363ac7c | 785 | |
cb6934f8 JA |
786 | /* |
787 | * Don't allow merge of different write hints, or for a hint with | |
788 | * non-hint IO. | |
789 | */ | |
790 | if (req->write_hint != next->write_hint) | |
791 | return NULL; | |
792 | ||
668ffc03 DLM |
793 | if (req->ioprio != next->ioprio) |
794 | return NULL; | |
795 | ||
d6d48196 JA |
796 | /* |
797 | * If we are allowed to merge, then append bio list | |
798 | * from next to rq and release next. merge_requests_fn | |
799 | * will have updated segment counts, update sector | |
445251d0 JA |
800 | * counts here. Handle DISCARDs separately, as they |
801 | * have separate settings. | |
d6d48196 | 802 | */ |
69840466 JW |
803 | |
804 | switch (blk_try_req_merge(req, next)) { | |
805 | case ELEVATOR_DISCARD_MERGE: | |
445251d0 JA |
806 | if (!req_attempt_discard_merge(q, req, next)) |
807 | return NULL; | |
69840466 JW |
808 | break; |
809 | case ELEVATOR_BACK_MERGE: | |
810 | if (!ll_merge_requests_fn(q, req, next)) | |
811 | return NULL; | |
812 | break; | |
813 | default: | |
b973cb7e | 814 | return NULL; |
69840466 | 815 | } |
d6d48196 | 816 | |
80a761fd TH |
817 | /* |
818 | * If failfast settings disagree or any of the two is already | |
819 | * a mixed merge, mark both as mixed before proceeding. This | |
820 | * makes sure that all involved bios have mixable attributes | |
821 | * set properly. | |
822 | */ | |
e8064021 | 823 | if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || |
80a761fd TH |
824 | (req->cmd_flags & REQ_FAILFAST_MASK) != |
825 | (next->cmd_flags & REQ_FAILFAST_MASK)) { | |
826 | blk_rq_set_mixed_merge(req); | |
827 | blk_rq_set_mixed_merge(next); | |
828 | } | |
829 | ||
d6d48196 | 830 | /* |
522a7775 OS |
831 | * At this point we have either done a back merge or front merge. We |
832 | * need the smaller start_time_ns of the merged requests to be the | |
833 | * current request for accounting purposes. | |
d6d48196 | 834 | */ |
522a7775 OS |
835 | if (next->start_time_ns < req->start_time_ns) |
836 | req->start_time_ns = next->start_time_ns; | |
d6d48196 JA |
837 | |
838 | req->biotail->bi_next = next->bio; | |
839 | req->biotail = next->biotail; | |
840 | ||
a2dec7b3 | 841 | req->__data_len += blk_rq_bytes(next); |
d6d48196 | 842 | |
2a5cf35c | 843 | if (!blk_discard_mergable(req)) |
445251d0 | 844 | elv_merge_requests(q, req, next); |
d6d48196 | 845 | |
42dad764 JM |
846 | /* |
847 | * 'next' is going away, so update stats accordingly | |
848 | */ | |
b9c54f56 | 849 | blk_account_io_merge_request(next); |
d6d48196 | 850 | |
a54895fa | 851 | trace_block_rq_merge(next); |
f3bdc62f | 852 | |
e4d750c9 JA |
853 | /* |
854 | * ownership of bio passed from next to req, return 'next' for | |
855 | * the caller to free | |
856 | */ | |
1cd96c24 | 857 | next->bio = NULL; |
b973cb7e | 858 | return next; |
d6d48196 JA |
859 | } |
860 | ||
eda5cc99 CH |
861 | static struct request *attempt_back_merge(struct request_queue *q, |
862 | struct request *rq) | |
d6d48196 JA |
863 | { |
864 | struct request *next = elv_latter_request(q, rq); | |
865 | ||
866 | if (next) | |
867 | return attempt_merge(q, rq, next); | |
868 | ||
b973cb7e | 869 | return NULL; |
d6d48196 JA |
870 | } |
871 | ||
eda5cc99 CH |
872 | static struct request *attempt_front_merge(struct request_queue *q, |
873 | struct request *rq) | |
d6d48196 JA |
874 | { |
875 | struct request *prev = elv_former_request(q, rq); | |
876 | ||
877 | if (prev) | |
878 | return attempt_merge(q, prev, rq); | |
879 | ||
b973cb7e | 880 | return NULL; |
d6d48196 | 881 | } |
5e84ea3a | 882 | |
fd2ef39c JK |
883 | /* |
884 | * Try to merge 'next' into 'rq'. Return true if the merge happened, false | |
885 | * otherwise. The caller is responsible for freeing 'next' if the merge | |
886 | * happened. | |
887 | */ | |
888 | bool blk_attempt_req_merge(struct request_queue *q, struct request *rq, | |
889 | struct request *next) | |
5e84ea3a | 890 | { |
fd2ef39c | 891 | return attempt_merge(q, rq, next); |
5e84ea3a | 892 | } |
050c8ea8 TH |
893 | |
894 | bool blk_rq_merge_ok(struct request *rq, struct bio *bio) | |
895 | { | |
e2a60da7 | 896 | if (!rq_mergeable(rq) || !bio_mergeable(bio)) |
050c8ea8 TH |
897 | return false; |
898 | ||
288dab8a | 899 | if (req_op(rq) != bio_op(bio)) |
f31dc1cd MP |
900 | return false; |
901 | ||
050c8ea8 TH |
902 | /* different data direction or already started, don't merge */ |
903 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
904 | return false; | |
905 | ||
2081a56b | 906 | /* must be same device */ |
309dca30 | 907 | if (rq->rq_disk != bio->bi_bdev->bd_disk) |
050c8ea8 TH |
908 | return false; |
909 | ||
910 | /* only merge integrity protected bio into ditto rq */ | |
4eaf99be | 911 | if (blk_integrity_merge_bio(rq->q, rq, bio) == false) |
050c8ea8 TH |
912 | return false; |
913 | ||
a892c8d5 ST |
914 | /* Only merge if the crypt contexts are compatible */ |
915 | if (!bio_crypt_rq_ctx_compatible(rq, bio)) | |
916 | return false; | |
917 | ||
4363ac7c | 918 | /* must be using the same buffer */ |
8fe0d473 | 919 | if (req_op(rq) == REQ_OP_WRITE_SAME && |
4363ac7c MP |
920 | !blk_write_same_mergeable(rq->bio, bio)) |
921 | return false; | |
922 | ||
cb6934f8 JA |
923 | /* |
924 | * Don't allow merge of different write hints, or for a hint with | |
925 | * non-hint IO. | |
926 | */ | |
927 | if (rq->write_hint != bio->bi_write_hint) | |
928 | return false; | |
929 | ||
668ffc03 DLM |
930 | if (rq->ioprio != bio_prio(bio)) |
931 | return false; | |
932 | ||
050c8ea8 TH |
933 | return true; |
934 | } | |
935 | ||
34fe7c05 | 936 | enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) |
050c8ea8 | 937 | { |
69840466 | 938 | if (blk_discard_mergable(rq)) |
1e739730 CH |
939 | return ELEVATOR_DISCARD_MERGE; |
940 | else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) | |
050c8ea8 | 941 | return ELEVATOR_BACK_MERGE; |
4f024f37 | 942 | else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) |
050c8ea8 TH |
943 | return ELEVATOR_FRONT_MERGE; |
944 | return ELEVATOR_NO_MERGE; | |
945 | } | |
8e756373 BW |
946 | |
947 | static void blk_account_io_merge_bio(struct request *req) | |
948 | { | |
949 | if (!blk_do_io_stat(req)) | |
950 | return; | |
951 | ||
952 | part_stat_lock(); | |
953 | part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); | |
954 | part_stat_unlock(); | |
955 | } | |
956 | ||
eda5cc99 CH |
957 | enum bio_merge_status { |
958 | BIO_MERGE_OK, | |
959 | BIO_MERGE_NONE, | |
960 | BIO_MERGE_FAILED, | |
961 | }; | |
962 | ||
963 | static enum bio_merge_status bio_attempt_back_merge(struct request *req, | |
964 | struct bio *bio, unsigned int nr_segs) | |
8e756373 BW |
965 | { |
966 | const int ff = bio->bi_opf & REQ_FAILFAST_MASK; | |
967 | ||
968 | if (!ll_back_merge_fn(req, bio, nr_segs)) | |
7d7ca7c5 | 969 | return BIO_MERGE_FAILED; |
8e756373 | 970 | |
e8a676d6 | 971 | trace_block_bio_backmerge(bio); |
8e756373 BW |
972 | rq_qos_merge(req->q, req, bio); |
973 | ||
974 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) | |
975 | blk_rq_set_mixed_merge(req); | |
976 | ||
977 | req->biotail->bi_next = bio; | |
978 | req->biotail = bio; | |
979 | req->__data_len += bio->bi_iter.bi_size; | |
980 | ||
981 | bio_crypt_free_ctx(bio); | |
982 | ||
983 | blk_account_io_merge_bio(req); | |
7d7ca7c5 | 984 | return BIO_MERGE_OK; |
8e756373 BW |
985 | } |
986 | ||
eda5cc99 CH |
987 | static enum bio_merge_status bio_attempt_front_merge(struct request *req, |
988 | struct bio *bio, unsigned int nr_segs) | |
8e756373 BW |
989 | { |
990 | const int ff = bio->bi_opf & REQ_FAILFAST_MASK; | |
991 | ||
992 | if (!ll_front_merge_fn(req, bio, nr_segs)) | |
7d7ca7c5 | 993 | return BIO_MERGE_FAILED; |
8e756373 | 994 | |
e8a676d6 | 995 | trace_block_bio_frontmerge(bio); |
8e756373 BW |
996 | rq_qos_merge(req->q, req, bio); |
997 | ||
998 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) | |
999 | blk_rq_set_mixed_merge(req); | |
1000 | ||
1001 | bio->bi_next = req->bio; | |
1002 | req->bio = bio; | |
1003 | ||
1004 | req->__sector = bio->bi_iter.bi_sector; | |
1005 | req->__data_len += bio->bi_iter.bi_size; | |
1006 | ||
1007 | bio_crypt_do_front_merge(req, bio); | |
1008 | ||
1009 | blk_account_io_merge_bio(req); | |
7d7ca7c5 | 1010 | return BIO_MERGE_OK; |
8e756373 BW |
1011 | } |
1012 | ||
eda5cc99 CH |
1013 | static enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q, |
1014 | struct request *req, struct bio *bio) | |
8e756373 BW |
1015 | { |
1016 | unsigned short segments = blk_rq_nr_discard_segments(req); | |
1017 | ||
1018 | if (segments >= queue_max_discard_segments(q)) | |
1019 | goto no_merge; | |
1020 | if (blk_rq_sectors(req) + bio_sectors(bio) > | |
1021 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) | |
1022 | goto no_merge; | |
1023 | ||
1024 | rq_qos_merge(q, req, bio); | |
1025 | ||
1026 | req->biotail->bi_next = bio; | |
1027 | req->biotail = bio; | |
1028 | req->__data_len += bio->bi_iter.bi_size; | |
1029 | req->nr_phys_segments = segments + 1; | |
1030 | ||
1031 | blk_account_io_merge_bio(req); | |
7d7ca7c5 | 1032 | return BIO_MERGE_OK; |
8e756373 BW |
1033 | no_merge: |
1034 | req_set_nomerge(q, req); | |
7d7ca7c5 BW |
1035 | return BIO_MERGE_FAILED; |
1036 | } | |
1037 | ||
1038 | static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q, | |
1039 | struct request *rq, | |
1040 | struct bio *bio, | |
1041 | unsigned int nr_segs, | |
1042 | bool sched_allow_merge) | |
1043 | { | |
1044 | if (!blk_rq_merge_ok(rq, bio)) | |
1045 | return BIO_MERGE_NONE; | |
1046 | ||
1047 | switch (blk_try_merge(rq, bio)) { | |
1048 | case ELEVATOR_BACK_MERGE: | |
265600b7 | 1049 | if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) |
7d7ca7c5 BW |
1050 | return bio_attempt_back_merge(rq, bio, nr_segs); |
1051 | break; | |
1052 | case ELEVATOR_FRONT_MERGE: | |
265600b7 | 1053 | if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) |
7d7ca7c5 BW |
1054 | return bio_attempt_front_merge(rq, bio, nr_segs); |
1055 | break; | |
1056 | case ELEVATOR_DISCARD_MERGE: | |
1057 | return bio_attempt_discard_merge(q, rq, bio); | |
1058 | default: | |
1059 | return BIO_MERGE_NONE; | |
1060 | } | |
1061 | ||
1062 | return BIO_MERGE_FAILED; | |
8e756373 BW |
1063 | } |
1064 | ||
1065 | /** | |
1066 | * blk_attempt_plug_merge - try to merge with %current's plugged list | |
1067 | * @q: request_queue new bio is being queued at | |
1068 | * @bio: new bio being queued | |
1069 | * @nr_segs: number of segments in @bio | |
87c037d1 JA |
1070 | * @same_queue_rq: output value, will be true if there's an existing request |
1071 | * from the passed in @q already in the plug list | |
8e756373 | 1072 | * |
d38a9c04 JA |
1073 | * Determine whether @bio being queued on @q can be merged with the previous |
1074 | * request on %current's plugged list. Returns %true if merge was successful, | |
8e756373 BW |
1075 | * otherwise %false. |
1076 | * | |
1077 | * Plugging coalesces IOs from the same issuer for the same purpose without | |
1078 | * going through @q->queue_lock. As such it's more of an issuing mechanism | |
1079 | * than scheduling, and the request, while may have elvpriv data, is not | |
1080 | * added on the elevator at this point. In addition, we don't have | |
1081 | * reliable access to the elevator outside queue lock. Only check basic | |
1082 | * merging parameters without querying the elevator. | |
1083 | * | |
1084 | * Caller must ensure !blk_queue_nomerges(q) beforehand. | |
1085 | */ | |
1086 | bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, | |
87c037d1 | 1087 | unsigned int nr_segs, bool *same_queue_rq) |
8e756373 BW |
1088 | { |
1089 | struct blk_plug *plug; | |
1090 | struct request *rq; | |
8e756373 BW |
1091 | |
1092 | plug = blk_mq_plug(q, bio); | |
bc490f81 | 1093 | if (!plug || rq_list_empty(plug->mq_list)) |
8e756373 BW |
1094 | return false; |
1095 | ||
d38a9c04 | 1096 | /* check the previously added entry for a quick merge attempt */ |
bc490f81 | 1097 | rq = rq_list_peek(&plug->mq_list); |
87c037d1 | 1098 | if (rq->q == q) { |
d38a9c04 JA |
1099 | /* |
1100 | * Only blk-mq multiple hardware queues case checks the rq in | |
1101 | * the same queue, there should be only one such rq in a queue | |
1102 | */ | |
87c037d1 | 1103 | *same_queue_rq = true; |
a1cb6537 ML |
1104 | |
1105 | if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) == | |
1106 | BIO_MERGE_OK) | |
1107 | return true; | |
8e756373 | 1108 | } |
8e756373 BW |
1109 | return false; |
1110 | } | |
bdc6a287 BW |
1111 | |
1112 | /* | |
1113 | * Iterate list of requests and see if we can merge this bio with any | |
1114 | * of them. | |
1115 | */ | |
1116 | bool blk_bio_list_merge(struct request_queue *q, struct list_head *list, | |
1117 | struct bio *bio, unsigned int nr_segs) | |
1118 | { | |
1119 | struct request *rq; | |
1120 | int checked = 8; | |
1121 | ||
1122 | list_for_each_entry_reverse(rq, list, queuelist) { | |
bdc6a287 BW |
1123 | if (!checked--) |
1124 | break; | |
1125 | ||
7d7ca7c5 BW |
1126 | switch (blk_attempt_bio_merge(q, rq, bio, nr_segs, true)) { |
1127 | case BIO_MERGE_NONE: | |
bdc6a287 | 1128 | continue; |
7d7ca7c5 BW |
1129 | case BIO_MERGE_OK: |
1130 | return true; | |
1131 | case BIO_MERGE_FAILED: | |
1132 | return false; | |
bdc6a287 BW |
1133 | } |
1134 | ||
bdc6a287 BW |
1135 | } |
1136 | ||
1137 | return false; | |
1138 | } | |
1139 | EXPORT_SYMBOL_GPL(blk_bio_list_merge); | |
eda5cc99 CH |
1140 | |
1141 | bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio, | |
1142 | unsigned int nr_segs, struct request **merged_request) | |
1143 | { | |
1144 | struct request *rq; | |
1145 | ||
1146 | switch (elv_merge(q, &rq, bio)) { | |
1147 | case ELEVATOR_BACK_MERGE: | |
1148 | if (!blk_mq_sched_allow_merge(q, rq, bio)) | |
1149 | return false; | |
1150 | if (bio_attempt_back_merge(rq, bio, nr_segs) != BIO_MERGE_OK) | |
1151 | return false; | |
1152 | *merged_request = attempt_back_merge(q, rq); | |
1153 | if (!*merged_request) | |
1154 | elv_merged_request(q, rq, ELEVATOR_BACK_MERGE); | |
1155 | return true; | |
1156 | case ELEVATOR_FRONT_MERGE: | |
1157 | if (!blk_mq_sched_allow_merge(q, rq, bio)) | |
1158 | return false; | |
1159 | if (bio_attempt_front_merge(rq, bio, nr_segs) != BIO_MERGE_OK) | |
1160 | return false; | |
1161 | *merged_request = attempt_front_merge(q, rq); | |
1162 | if (!*merged_request) | |
1163 | elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE); | |
1164 | return true; | |
1165 | case ELEVATOR_DISCARD_MERGE: | |
1166 | return bio_attempt_discard_merge(q, rq, bio) == BIO_MERGE_OK; | |
1167 | default: | |
1168 | return false; | |
1169 | } | |
1170 | } | |
1171 | EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge); |