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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> | |
9 | #include <linux/scatterlist.h> | |
10 | ||
cda22646 MK |
11 | #include <trace/events/block.h> |
12 | ||
d6d48196 JA |
13 | #include "blk.h" |
14 | ||
e9907009 CH |
15 | static inline bool bio_will_gap(struct request_queue *q, |
16 | struct request *prev_rq, struct bio *prev, struct bio *next) | |
17 | { | |
18 | struct bio_vec pb, nb; | |
19 | ||
20 | if (!bio_has_data(prev) || !queue_virt_boundary(q)) | |
21 | return false; | |
22 | ||
23 | /* | |
24 | * Don't merge if the 1st bio starts with non-zero offset, otherwise it | |
25 | * is quite difficult to respect the sg gap limit. We work hard to | |
26 | * merge a huge number of small single bios in case of mkfs. | |
27 | */ | |
28 | if (prev_rq) | |
29 | bio_get_first_bvec(prev_rq->bio, &pb); | |
30 | else | |
31 | bio_get_first_bvec(prev, &pb); | |
df376b2e | 32 | if (pb.bv_offset & queue_virt_boundary(q)) |
e9907009 CH |
33 | return true; |
34 | ||
35 | /* | |
36 | * We don't need to worry about the situation that the merged segment | |
37 | * ends in unaligned virt boundary: | |
38 | * | |
39 | * - if 'pb' ends aligned, the merged segment ends aligned | |
40 | * - if 'pb' ends unaligned, the next bio must include | |
41 | * one single bvec of 'nb', otherwise the 'nb' can't | |
42 | * merge with 'pb' | |
43 | */ | |
44 | bio_get_last_bvec(prev, &pb); | |
45 | bio_get_first_bvec(next, &nb); | |
200a9aff | 46 | if (biovec_phys_mergeable(q, &pb, &nb)) |
e9907009 CH |
47 | return false; |
48 | return __bvec_gap_to_prev(q, &pb, nb.bv_offset); | |
49 | } | |
50 | ||
51 | static inline bool req_gap_back_merge(struct request *req, struct bio *bio) | |
52 | { | |
53 | return bio_will_gap(req->q, req, req->biotail, bio); | |
54 | } | |
55 | ||
56 | static inline bool req_gap_front_merge(struct request *req, struct bio *bio) | |
57 | { | |
58 | return bio_will_gap(req->q, NULL, bio, req->bio); | |
59 | } | |
60 | ||
54efd50b KO |
61 | static struct bio *blk_bio_discard_split(struct request_queue *q, |
62 | struct bio *bio, | |
bdced438 ML |
63 | struct bio_set *bs, |
64 | unsigned *nsegs) | |
54efd50b KO |
65 | { |
66 | unsigned int max_discard_sectors, granularity; | |
67 | int alignment; | |
68 | sector_t tmp; | |
69 | unsigned split_sectors; | |
70 | ||
bdced438 ML |
71 | *nsegs = 1; |
72 | ||
54efd50b KO |
73 | /* Zero-sector (unknown) and one-sector granularities are the same. */ |
74 | granularity = max(q->limits.discard_granularity >> 9, 1U); | |
75 | ||
1adfc5e4 ML |
76 | max_discard_sectors = min(q->limits.max_discard_sectors, |
77 | bio_allowed_max_sectors(q)); | |
54efd50b KO |
78 | max_discard_sectors -= max_discard_sectors % granularity; |
79 | ||
80 | if (unlikely(!max_discard_sectors)) { | |
81 | /* XXX: warn */ | |
82 | return NULL; | |
83 | } | |
84 | ||
85 | if (bio_sectors(bio) <= max_discard_sectors) | |
86 | return NULL; | |
87 | ||
88 | split_sectors = max_discard_sectors; | |
89 | ||
90 | /* | |
91 | * If the next starting sector would be misaligned, stop the discard at | |
92 | * the previous aligned sector. | |
93 | */ | |
94 | alignment = (q->limits.discard_alignment >> 9) % granularity; | |
95 | ||
96 | tmp = bio->bi_iter.bi_sector + split_sectors - alignment; | |
97 | tmp = sector_div(tmp, granularity); | |
98 | ||
99 | if (split_sectors > tmp) | |
100 | split_sectors -= tmp; | |
101 | ||
102 | return bio_split(bio, split_sectors, GFP_NOIO, bs); | |
103 | } | |
104 | ||
885fa13f CH |
105 | static struct bio *blk_bio_write_zeroes_split(struct request_queue *q, |
106 | struct bio *bio, struct bio_set *bs, unsigned *nsegs) | |
107 | { | |
d665e12a | 108 | *nsegs = 0; |
885fa13f CH |
109 | |
110 | if (!q->limits.max_write_zeroes_sectors) | |
111 | return NULL; | |
112 | ||
113 | if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors) | |
114 | return NULL; | |
115 | ||
116 | return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs); | |
117 | } | |
118 | ||
54efd50b KO |
119 | static struct bio *blk_bio_write_same_split(struct request_queue *q, |
120 | struct bio *bio, | |
bdced438 ML |
121 | struct bio_set *bs, |
122 | unsigned *nsegs) | |
54efd50b | 123 | { |
bdced438 ML |
124 | *nsegs = 1; |
125 | ||
54efd50b KO |
126 | if (!q->limits.max_write_same_sectors) |
127 | return NULL; | |
128 | ||
129 | if (bio_sectors(bio) <= q->limits.max_write_same_sectors) | |
130 | return NULL; | |
131 | ||
132 | return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); | |
133 | } | |
134 | ||
9cc5169c BVA |
135 | /* |
136 | * Return the maximum number of sectors from the start of a bio that may be | |
137 | * submitted as a single request to a block device. If enough sectors remain, | |
138 | * align the end to the physical block size. Otherwise align the end to the | |
139 | * logical block size. This approach minimizes the number of non-aligned | |
140 | * requests that are submitted to a block device if the start of a bio is not | |
141 | * aligned to a physical block boundary. | |
142 | */ | |
d0e5fbb0 ML |
143 | static inline unsigned get_max_io_size(struct request_queue *q, |
144 | struct bio *bio) | |
145 | { | |
146 | unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector); | |
9cc5169c BVA |
147 | unsigned max_sectors = sectors; |
148 | unsigned pbs = queue_physical_block_size(q) >> SECTOR_SHIFT; | |
149 | unsigned lbs = queue_logical_block_size(q) >> SECTOR_SHIFT; | |
150 | unsigned start_offset = bio->bi_iter.bi_sector & (pbs - 1); | |
d0e5fbb0 | 151 | |
9cc5169c BVA |
152 | max_sectors += start_offset; |
153 | max_sectors &= ~(pbs - 1); | |
154 | if (max_sectors > start_offset) | |
155 | return max_sectors - start_offset; | |
d0e5fbb0 | 156 | |
9cc5169c | 157 | return sectors & (lbs - 1); |
d0e5fbb0 ML |
158 | } |
159 | ||
af2c68fe | 160 | static unsigned get_max_segment_size(const struct request_queue *q, |
dcebd755 ML |
161 | unsigned offset) |
162 | { | |
163 | unsigned long mask = queue_segment_boundary(q); | |
164 | ||
165 | /* default segment boundary mask means no boundary limit */ | |
166 | if (mask == BLK_SEG_BOUNDARY_MASK) | |
167 | return queue_max_segment_size(q); | |
168 | ||
169 | return min_t(unsigned long, mask - (mask & offset) + 1, | |
170 | queue_max_segment_size(q)); | |
171 | } | |
172 | ||
708b25b3 BVA |
173 | /** |
174 | * bvec_split_segs - verify whether or not a bvec should be split in the middle | |
175 | * @q: [in] request queue associated with the bio associated with @bv | |
176 | * @bv: [in] bvec to examine | |
177 | * @nsegs: [in,out] Number of segments in the bio being built. Incremented | |
178 | * by the number of segments from @bv that may be appended to that | |
179 | * bio without exceeding @max_segs | |
180 | * @sectors: [in,out] Number of sectors in the bio being built. Incremented | |
181 | * by the number of sectors from @bv that may be appended to that | |
182 | * bio without exceeding @max_sectors | |
183 | * @max_segs: [in] upper bound for *@nsegs | |
184 | * @max_sectors: [in] upper bound for *@sectors | |
185 | * | |
186 | * When splitting a bio, it can happen that a bvec is encountered that is too | |
187 | * big to fit in a single segment and hence that it has to be split in the | |
188 | * middle. This function verifies whether or not that should happen. The value | |
189 | * %true is returned if and only if appending the entire @bv to a bio with | |
190 | * *@nsegs segments and *@sectors sectors would make that bio unacceptable for | |
191 | * the block driver. | |
dcebd755 | 192 | */ |
af2c68fe BVA |
193 | static bool bvec_split_segs(const struct request_queue *q, |
194 | const struct bio_vec *bv, unsigned *nsegs, | |
708b25b3 BVA |
195 | unsigned *sectors, unsigned max_segs, |
196 | unsigned max_sectors) | |
dcebd755 | 197 | { |
708b25b3 BVA |
198 | unsigned max_len = (min(max_sectors, UINT_MAX >> 9) - *sectors) << 9; |
199 | unsigned len = min(bv->bv_len, max_len); | |
dcebd755 | 200 | unsigned total_len = 0; |
ff9811b3 | 201 | unsigned seg_size = 0; |
dcebd755 | 202 | |
ff9811b3 | 203 | while (len && *nsegs < max_segs) { |
dcebd755 ML |
204 | seg_size = get_max_segment_size(q, bv->bv_offset + total_len); |
205 | seg_size = min(seg_size, len); | |
206 | ||
ff9811b3 | 207 | (*nsegs)++; |
dcebd755 ML |
208 | total_len += seg_size; |
209 | len -= seg_size; | |
210 | ||
211 | if ((bv->bv_offset + total_len) & queue_virt_boundary(q)) | |
212 | break; | |
213 | } | |
214 | ||
ff9811b3 | 215 | *sectors += total_len >> 9; |
dcebd755 | 216 | |
708b25b3 BVA |
217 | /* tell the caller to split the bvec if it is too big to fit */ |
218 | return len > 0 || bv->bv_len > max_len; | |
dcebd755 ML |
219 | } |
220 | ||
dad77584 BVA |
221 | /** |
222 | * blk_bio_segment_split - split a bio in two bios | |
223 | * @q: [in] request queue pointer | |
224 | * @bio: [in] bio to be split | |
225 | * @bs: [in] bio set to allocate the clone from | |
226 | * @segs: [out] number of segments in the bio with the first half of the sectors | |
227 | * | |
228 | * Clone @bio, update the bi_iter of the clone to represent the first sectors | |
229 | * of @bio and update @bio->bi_iter to represent the remaining sectors. The | |
230 | * following is guaranteed for the cloned bio: | |
231 | * - That it has at most get_max_io_size(@q, @bio) sectors. | |
232 | * - That it has at most queue_max_segments(@q) segments. | |
233 | * | |
234 | * Except for discard requests the cloned bio will point at the bi_io_vec of | |
235 | * the original bio. It is the responsibility of the caller to ensure that the | |
236 | * original bio is not freed before the cloned bio. The caller is also | |
237 | * responsible for ensuring that @bs is only destroyed after processing of the | |
238 | * split bio has finished. | |
239 | */ | |
54efd50b KO |
240 | static struct bio *blk_bio_segment_split(struct request_queue *q, |
241 | struct bio *bio, | |
bdced438 ML |
242 | struct bio_set *bs, |
243 | unsigned *segs) | |
54efd50b | 244 | { |
5014c311 | 245 | struct bio_vec bv, bvprv, *bvprvp = NULL; |
54efd50b | 246 | struct bvec_iter iter; |
6869875f | 247 | unsigned nsegs = 0, sectors = 0; |
d0e5fbb0 | 248 | const unsigned max_sectors = get_max_io_size(q, bio); |
05b700ba | 249 | const unsigned max_segs = queue_max_segments(q); |
54efd50b | 250 | |
dcebd755 | 251 | bio_for_each_bvec(bv, bio, iter) { |
54efd50b KO |
252 | /* |
253 | * If the queue doesn't support SG gaps and adding this | |
254 | * offset would create a gap, disallow it. | |
255 | */ | |
5014c311 | 256 | if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) |
54efd50b KO |
257 | goto split; |
258 | ||
708b25b3 BVA |
259 | if (nsegs < max_segs && |
260 | sectors + (bv.bv_len >> 9) <= max_sectors && | |
261 | bv.bv_offset + bv.bv_len <= PAGE_SIZE) { | |
262 | nsegs++; | |
263 | sectors += bv.bv_len >> 9; | |
264 | } else if (bvec_split_segs(q, &bv, &nsegs, §ors, max_segs, | |
265 | max_sectors)) { | |
cf8c0c6a | 266 | goto split; |
e36f6204 KB |
267 | } |
268 | ||
54efd50b | 269 | bvprv = bv; |
578270bf | 270 | bvprvp = &bvprv; |
54efd50b KO |
271 | } |
272 | ||
d627065d CH |
273 | *segs = nsegs; |
274 | return NULL; | |
54efd50b | 275 | split: |
bdced438 | 276 | *segs = nsegs; |
d627065d | 277 | return bio_split(bio, sectors, GFP_NOIO, bs); |
54efd50b KO |
278 | } |
279 | ||
dad77584 BVA |
280 | /** |
281 | * __blk_queue_split - split a bio and submit the second half | |
282 | * @q: [in] request queue pointer | |
283 | * @bio: [in, out] bio to be split | |
284 | * @nr_segs: [out] number of segments in the first bio | |
285 | * | |
286 | * Split a bio into two bios, chain the two bios, submit the second half and | |
287 | * store a pointer to the first half in *@bio. If the second bio is still too | |
288 | * big it will be split by a recursive call to this function. Since this | |
289 | * function may allocate a new bio from @q->bio_split, it is the responsibility | |
290 | * of the caller to ensure that @q is only released after processing of the | |
291 | * split bio has finished. | |
292 | */ | |
14ccb66b CH |
293 | void __blk_queue_split(struct request_queue *q, struct bio **bio, |
294 | unsigned int *nr_segs) | |
54efd50b | 295 | { |
14ccb66b | 296 | struct bio *split; |
54efd50b | 297 | |
7afafc8a AH |
298 | switch (bio_op(*bio)) { |
299 | case REQ_OP_DISCARD: | |
300 | case REQ_OP_SECURE_ERASE: | |
14ccb66b | 301 | split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs); |
7afafc8a | 302 | break; |
a6f0788e | 303 | case REQ_OP_WRITE_ZEROES: |
14ccb66b CH |
304 | split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split, |
305 | nr_segs); | |
a6f0788e | 306 | break; |
7afafc8a | 307 | case REQ_OP_WRITE_SAME: |
14ccb66b CH |
308 | split = blk_bio_write_same_split(q, *bio, &q->bio_split, |
309 | nr_segs); | |
7afafc8a AH |
310 | break; |
311 | default: | |
14ccb66b | 312 | split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs); |
7afafc8a AH |
313 | break; |
314 | } | |
bdced438 | 315 | |
54efd50b | 316 | if (split) { |
6ac45aeb | 317 | /* there isn't chance to merge the splitted bio */ |
1eff9d32 | 318 | split->bi_opf |= REQ_NOMERGE; |
6ac45aeb | 319 | |
947b7ac1 JA |
320 | /* |
321 | * Since we're recursing into make_request here, ensure | |
322 | * that we mark this bio as already having entered the queue. | |
323 | * If not, and the queue is going away, we can get stuck | |
324 | * forever on waiting for the queue reference to drop. But | |
325 | * that will never happen, as we're already holding a | |
326 | * reference to it. | |
327 | */ | |
328 | bio_set_flag(*bio, BIO_QUEUE_ENTERED); | |
329 | ||
54efd50b | 330 | bio_chain(split, *bio); |
cda22646 | 331 | trace_block_split(q, split, (*bio)->bi_iter.bi_sector); |
54efd50b KO |
332 | generic_make_request(*bio); |
333 | *bio = split; | |
334 | } | |
335 | } | |
14ccb66b | 336 | |
dad77584 BVA |
337 | /** |
338 | * blk_queue_split - split a bio and submit the second half | |
339 | * @q: [in] request queue pointer | |
340 | * @bio: [in, out] bio to be split | |
341 | * | |
342 | * Split a bio into two bios, chains the two bios, submit the second half and | |
343 | * store a pointer to the first half in *@bio. Since this function may allocate | |
344 | * a new bio from @q->bio_split, it is the responsibility of the caller to | |
345 | * ensure that @q is only released after processing of the split bio has | |
346 | * finished. | |
347 | */ | |
14ccb66b CH |
348 | void blk_queue_split(struct request_queue *q, struct bio **bio) |
349 | { | |
350 | unsigned int nr_segs; | |
351 | ||
352 | __blk_queue_split(q, bio, &nr_segs); | |
353 | } | |
54efd50b KO |
354 | EXPORT_SYMBOL(blk_queue_split); |
355 | ||
e9cd19c0 | 356 | unsigned int blk_recalc_rq_segments(struct request *rq) |
d6d48196 | 357 | { |
6869875f | 358 | unsigned int nr_phys_segs = 0; |
ff9811b3 | 359 | unsigned int nr_sectors = 0; |
e9cd19c0 | 360 | struct req_iterator iter; |
6869875f | 361 | struct bio_vec bv; |
d6d48196 | 362 | |
e9cd19c0 | 363 | if (!rq->bio) |
1e428079 | 364 | return 0; |
d6d48196 | 365 | |
e9cd19c0 | 366 | switch (bio_op(rq->bio)) { |
a6f0788e CK |
367 | case REQ_OP_DISCARD: |
368 | case REQ_OP_SECURE_ERASE: | |
a6f0788e | 369 | case REQ_OP_WRITE_ZEROES: |
f9d03f96 CH |
370 | return 0; |
371 | case REQ_OP_WRITE_SAME: | |
5cb8850c | 372 | return 1; |
a6f0788e | 373 | } |
5cb8850c | 374 | |
e9cd19c0 | 375 | rq_for_each_bvec(bv, rq, iter) |
ff9811b3 | 376 | bvec_split_segs(rq->q, &bv, &nr_phys_segs, &nr_sectors, |
708b25b3 | 377 | UINT_MAX, UINT_MAX); |
1e428079 JA |
378 | return nr_phys_segs; |
379 | } | |
380 | ||
48d7727c | 381 | static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, |
862e5a5e ML |
382 | struct scatterlist *sglist) |
383 | { | |
384 | if (!*sg) | |
385 | return sglist; | |
386 | ||
387 | /* | |
388 | * If the driver previously mapped a shorter list, we could see a | |
389 | * termination bit prematurely unless it fully inits the sg table | |
390 | * on each mapping. We KNOW that there must be more entries here | |
391 | * or the driver would be buggy, so force clear the termination bit | |
392 | * to avoid doing a full sg_init_table() in drivers for each command. | |
393 | */ | |
394 | sg_unmark_end(*sg); | |
395 | return sg_next(*sg); | |
396 | } | |
397 | ||
398 | static unsigned blk_bvec_map_sg(struct request_queue *q, | |
399 | struct bio_vec *bvec, struct scatterlist *sglist, | |
400 | struct scatterlist **sg) | |
401 | { | |
402 | unsigned nbytes = bvec->bv_len; | |
8a96a0e4 | 403 | unsigned nsegs = 0, total = 0; |
862e5a5e ML |
404 | |
405 | while (nbytes > 0) { | |
8a96a0e4 CH |
406 | unsigned offset = bvec->bv_offset + total; |
407 | unsigned len = min(get_max_segment_size(q, offset), nbytes); | |
f9f76879 CH |
408 | struct page *page = bvec->bv_page; |
409 | ||
410 | /* | |
411 | * Unfortunately a fair number of drivers barf on scatterlists | |
412 | * that have an offset larger than PAGE_SIZE, despite other | |
413 | * subsystems dealing with that invariant just fine. For now | |
414 | * stick to the legacy format where we never present those from | |
415 | * the block layer, but the code below should be removed once | |
416 | * these offenders (mostly MMC/SD drivers) are fixed. | |
417 | */ | |
418 | page += (offset >> PAGE_SHIFT); | |
419 | offset &= ~PAGE_MASK; | |
862e5a5e ML |
420 | |
421 | *sg = blk_next_sg(sg, sglist); | |
f9f76879 | 422 | sg_set_page(*sg, page, len, offset); |
862e5a5e | 423 | |
8a96a0e4 CH |
424 | total += len; |
425 | nbytes -= len; | |
862e5a5e ML |
426 | nsegs++; |
427 | } | |
428 | ||
429 | return nsegs; | |
430 | } | |
431 | ||
16e3e418 ML |
432 | static inline int __blk_bvec_map_sg(struct bio_vec bv, |
433 | struct scatterlist *sglist, struct scatterlist **sg) | |
434 | { | |
435 | *sg = blk_next_sg(sg, sglist); | |
436 | sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); | |
437 | return 1; | |
438 | } | |
439 | ||
f6970f83 ML |
440 | /* only try to merge bvecs into one sg if they are from two bios */ |
441 | static inline bool | |
442 | __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec, | |
443 | struct bio_vec *bvprv, struct scatterlist **sg) | |
963ab9e5 AH |
444 | { |
445 | ||
446 | int nbytes = bvec->bv_len; | |
447 | ||
f6970f83 ML |
448 | if (!*sg) |
449 | return false; | |
963ab9e5 | 450 | |
f6970f83 ML |
451 | if ((*sg)->length + nbytes > queue_max_segment_size(q)) |
452 | return false; | |
453 | ||
454 | if (!biovec_phys_mergeable(q, bvprv, bvec)) | |
455 | return false; | |
456 | ||
457 | (*sg)->length += nbytes; | |
458 | ||
459 | return true; | |
963ab9e5 AH |
460 | } |
461 | ||
5cb8850c KO |
462 | static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, |
463 | struct scatterlist *sglist, | |
464 | struct scatterlist **sg) | |
d6d48196 | 465 | { |
b21e11c5 | 466 | struct bio_vec uninitialized_var(bvec), bvprv = { NULL }; |
5cb8850c | 467 | struct bvec_iter iter; |
38417468 | 468 | int nsegs = 0; |
f6970f83 | 469 | bool new_bio = false; |
5cb8850c | 470 | |
f6970f83 ML |
471 | for_each_bio(bio) { |
472 | bio_for_each_bvec(bvec, bio, iter) { | |
473 | /* | |
474 | * Only try to merge bvecs from two bios given we | |
475 | * have done bio internal merge when adding pages | |
476 | * to bio | |
477 | */ | |
478 | if (new_bio && | |
479 | __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg)) | |
480 | goto next_bvec; | |
481 | ||
482 | if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE) | |
483 | nsegs += __blk_bvec_map_sg(bvec, sglist, sg); | |
484 | else | |
485 | nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg); | |
486 | next_bvec: | |
487 | new_bio = false; | |
488 | } | |
b21e11c5 ML |
489 | if (likely(bio->bi_iter.bi_size)) { |
490 | bvprv = bvec; | |
491 | new_bio = true; | |
492 | } | |
f6970f83 | 493 | } |
d6d48196 | 494 | |
5cb8850c KO |
495 | return nsegs; |
496 | } | |
497 | ||
498 | /* | |
499 | * map a request to scatterlist, return number of sg entries setup. Caller | |
500 | * must make sure sg can hold rq->nr_phys_segments entries | |
501 | */ | |
502 | int blk_rq_map_sg(struct request_queue *q, struct request *rq, | |
503 | struct scatterlist *sglist) | |
504 | { | |
505 | struct scatterlist *sg = NULL; | |
506 | int nsegs = 0; | |
507 | ||
f9d03f96 | 508 | if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) |
cae6c2e5 | 509 | nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, &sg); |
f9d03f96 | 510 | else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME) |
cae6c2e5 | 511 | nsegs = __blk_bvec_map_sg(bio_iovec(rq->bio), sglist, &sg); |
f9d03f96 | 512 | else if (rq->bio) |
5cb8850c | 513 | nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); |
f18573ab | 514 | |
e8064021 | 515 | if (unlikely(rq->rq_flags & RQF_COPY_USER) && |
2e46e8b2 TH |
516 | (blk_rq_bytes(rq) & q->dma_pad_mask)) { |
517 | unsigned int pad_len = | |
518 | (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; | |
f18573ab FT |
519 | |
520 | sg->length += pad_len; | |
521 | rq->extra_len += pad_len; | |
522 | } | |
523 | ||
2fb98e84 | 524 | if (q->dma_drain_size && q->dma_drain_needed(rq)) { |
a8ebb056 | 525 | if (op_is_write(req_op(rq))) |
db0a2e00 TH |
526 | memset(q->dma_drain_buffer, 0, q->dma_drain_size); |
527 | ||
da81ed16 | 528 | sg_unmark_end(sg); |
d6d48196 JA |
529 | sg = sg_next(sg); |
530 | sg_set_page(sg, virt_to_page(q->dma_drain_buffer), | |
531 | q->dma_drain_size, | |
532 | ((unsigned long)q->dma_drain_buffer) & | |
533 | (PAGE_SIZE - 1)); | |
534 | nsegs++; | |
7a85f889 | 535 | rq->extra_len += q->dma_drain_size; |
d6d48196 JA |
536 | } |
537 | ||
538 | if (sg) | |
539 | sg_mark_end(sg); | |
540 | ||
12e57f59 ML |
541 | /* |
542 | * Something must have been wrong if the figured number of | |
543 | * segment is bigger than number of req's physical segments | |
544 | */ | |
f9d03f96 | 545 | WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); |
12e57f59 | 546 | |
d6d48196 JA |
547 | return nsegs; |
548 | } | |
d6d48196 JA |
549 | EXPORT_SYMBOL(blk_rq_map_sg); |
550 | ||
14ccb66b CH |
551 | static inline int ll_new_hw_segment(struct request *req, struct bio *bio, |
552 | unsigned int nr_phys_segs) | |
d6d48196 | 553 | { |
14ccb66b | 554 | if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(req->q)) |
13f05c8d MP |
555 | goto no_merge; |
556 | ||
14ccb66b | 557 | if (blk_integrity_merge_bio(req->q, req, bio) == false) |
13f05c8d | 558 | goto no_merge; |
d6d48196 JA |
559 | |
560 | /* | |
561 | * This will form the start of a new hw segment. Bump both | |
562 | * counters. | |
563 | */ | |
d6d48196 JA |
564 | req->nr_phys_segments += nr_phys_segs; |
565 | return 1; | |
13f05c8d MP |
566 | |
567 | no_merge: | |
14ccb66b | 568 | req_set_nomerge(req->q, req); |
13f05c8d | 569 | return 0; |
d6d48196 JA |
570 | } |
571 | ||
14ccb66b | 572 | int ll_back_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs) |
d6d48196 | 573 | { |
5e7c4274 JA |
574 | if (req_gap_back_merge(req, bio)) |
575 | return 0; | |
7f39add3 SG |
576 | if (blk_integrity_rq(req) && |
577 | integrity_req_gap_back_merge(req, bio)) | |
578 | return 0; | |
f31dc1cd | 579 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
17007f39 | 580 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) { |
14ccb66b | 581 | req_set_nomerge(req->q, req); |
d6d48196 JA |
582 | return 0; |
583 | } | |
d6d48196 | 584 | |
14ccb66b | 585 | return ll_new_hw_segment(req, bio, nr_segs); |
d6d48196 JA |
586 | } |
587 | ||
14ccb66b | 588 | int ll_front_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs) |
d6d48196 | 589 | { |
5e7c4274 JA |
590 | if (req_gap_front_merge(req, bio)) |
591 | return 0; | |
7f39add3 SG |
592 | if (blk_integrity_rq(req) && |
593 | integrity_req_gap_front_merge(req, bio)) | |
594 | return 0; | |
f31dc1cd | 595 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
17007f39 | 596 | blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { |
14ccb66b | 597 | req_set_nomerge(req->q, req); |
d6d48196 JA |
598 | return 0; |
599 | } | |
d6d48196 | 600 | |
14ccb66b | 601 | return ll_new_hw_segment(req, bio, nr_segs); |
d6d48196 JA |
602 | } |
603 | ||
445251d0 JA |
604 | static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, |
605 | struct request *next) | |
606 | { | |
607 | unsigned short segments = blk_rq_nr_discard_segments(req); | |
608 | ||
609 | if (segments >= queue_max_discard_segments(q)) | |
610 | goto no_merge; | |
611 | if (blk_rq_sectors(req) + bio_sectors(next->bio) > | |
612 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) | |
613 | goto no_merge; | |
614 | ||
615 | req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); | |
616 | return true; | |
617 | no_merge: | |
618 | req_set_nomerge(q, req); | |
619 | return false; | |
620 | } | |
621 | ||
d6d48196 JA |
622 | static int ll_merge_requests_fn(struct request_queue *q, struct request *req, |
623 | struct request *next) | |
624 | { | |
625 | int total_phys_segments; | |
d6d48196 | 626 | |
5e7c4274 | 627 | if (req_gap_back_merge(req, next->bio)) |
854fbb9c KB |
628 | return 0; |
629 | ||
d6d48196 JA |
630 | /* |
631 | * Will it become too large? | |
632 | */ | |
f31dc1cd | 633 | if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > |
17007f39 | 634 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) |
d6d48196 JA |
635 | return 0; |
636 | ||
637 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
8a78362c | 638 | if (total_phys_segments > queue_max_segments(q)) |
d6d48196 JA |
639 | return 0; |
640 | ||
4eaf99be | 641 | if (blk_integrity_merge_rq(q, req, next) == false) |
13f05c8d MP |
642 | return 0; |
643 | ||
d6d48196 JA |
644 | /* Merge is OK... */ |
645 | req->nr_phys_segments = total_phys_segments; | |
d6d48196 JA |
646 | return 1; |
647 | } | |
648 | ||
80a761fd TH |
649 | /** |
650 | * blk_rq_set_mixed_merge - mark a request as mixed merge | |
651 | * @rq: request to mark as mixed merge | |
652 | * | |
653 | * Description: | |
654 | * @rq is about to be mixed merged. Make sure the attributes | |
655 | * which can be mixed are set in each bio and mark @rq as mixed | |
656 | * merged. | |
657 | */ | |
658 | void blk_rq_set_mixed_merge(struct request *rq) | |
659 | { | |
660 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
661 | struct bio *bio; | |
662 | ||
e8064021 | 663 | if (rq->rq_flags & RQF_MIXED_MERGE) |
80a761fd TH |
664 | return; |
665 | ||
666 | /* | |
667 | * @rq will no longer represent mixable attributes for all the | |
668 | * contained bios. It will just track those of the first one. | |
669 | * Distributes the attributs to each bio. | |
670 | */ | |
671 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
1eff9d32 JA |
672 | WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && |
673 | (bio->bi_opf & REQ_FAILFAST_MASK) != ff); | |
674 | bio->bi_opf |= ff; | |
80a761fd | 675 | } |
e8064021 | 676 | rq->rq_flags |= RQF_MIXED_MERGE; |
80a761fd TH |
677 | } |
678 | ||
26308eab JM |
679 | static void blk_account_io_merge(struct request *req) |
680 | { | |
681 | if (blk_do_io_stat(req)) { | |
682 | struct hd_struct *part; | |
26308eab | 683 | |
112f158f | 684 | part_stat_lock(); |
09e099d4 | 685 | part = req->part; |
26308eab | 686 | |
d62e26b3 | 687 | part_dec_in_flight(req->q, part, rq_data_dir(req)); |
26308eab | 688 | |
6c23a968 | 689 | hd_struct_put(part); |
26308eab JM |
690 | part_stat_unlock(); |
691 | } | |
692 | } | |
69840466 JW |
693 | /* |
694 | * Two cases of handling DISCARD merge: | |
695 | * If max_discard_segments > 1, the driver takes every bio | |
696 | * as a range and send them to controller together. The ranges | |
697 | * needn't to be contiguous. | |
698 | * Otherwise, the bios/requests will be handled as same as | |
699 | * others which should be contiguous. | |
700 | */ | |
701 | static inline bool blk_discard_mergable(struct request *req) | |
702 | { | |
703 | if (req_op(req) == REQ_OP_DISCARD && | |
704 | queue_max_discard_segments(req->q) > 1) | |
705 | return true; | |
706 | return false; | |
707 | } | |
708 | ||
e96c0d83 EB |
709 | static enum elv_merge blk_try_req_merge(struct request *req, |
710 | struct request *next) | |
69840466 JW |
711 | { |
712 | if (blk_discard_mergable(req)) | |
713 | return ELEVATOR_DISCARD_MERGE; | |
714 | else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) | |
715 | return ELEVATOR_BACK_MERGE; | |
716 | ||
717 | return ELEVATOR_NO_MERGE; | |
718 | } | |
26308eab | 719 | |
d6d48196 | 720 | /* |
b973cb7e JA |
721 | * For non-mq, this has to be called with the request spinlock acquired. |
722 | * For mq with scheduling, the appropriate queue wide lock should be held. | |
d6d48196 | 723 | */ |
b973cb7e JA |
724 | static struct request *attempt_merge(struct request_queue *q, |
725 | struct request *req, struct request *next) | |
d6d48196 JA |
726 | { |
727 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
b973cb7e | 728 | return NULL; |
d6d48196 | 729 | |
288dab8a | 730 | if (req_op(req) != req_op(next)) |
b973cb7e | 731 | return NULL; |
f31dc1cd | 732 | |
d6d48196 | 733 | if (rq_data_dir(req) != rq_data_dir(next) |
2081a56b | 734 | || req->rq_disk != next->rq_disk) |
b973cb7e | 735 | return NULL; |
d6d48196 | 736 | |
8fe0d473 | 737 | if (req_op(req) == REQ_OP_WRITE_SAME && |
4363ac7c | 738 | !blk_write_same_mergeable(req->bio, next->bio)) |
b973cb7e | 739 | return NULL; |
4363ac7c | 740 | |
cb6934f8 JA |
741 | /* |
742 | * Don't allow merge of different write hints, or for a hint with | |
743 | * non-hint IO. | |
744 | */ | |
745 | if (req->write_hint != next->write_hint) | |
746 | return NULL; | |
747 | ||
668ffc03 DLM |
748 | if (req->ioprio != next->ioprio) |
749 | return NULL; | |
750 | ||
d6d48196 JA |
751 | /* |
752 | * If we are allowed to merge, then append bio list | |
753 | * from next to rq and release next. merge_requests_fn | |
754 | * will have updated segment counts, update sector | |
445251d0 JA |
755 | * counts here. Handle DISCARDs separately, as they |
756 | * have separate settings. | |
d6d48196 | 757 | */ |
69840466 JW |
758 | |
759 | switch (blk_try_req_merge(req, next)) { | |
760 | case ELEVATOR_DISCARD_MERGE: | |
445251d0 JA |
761 | if (!req_attempt_discard_merge(q, req, next)) |
762 | return NULL; | |
69840466 JW |
763 | break; |
764 | case ELEVATOR_BACK_MERGE: | |
765 | if (!ll_merge_requests_fn(q, req, next)) | |
766 | return NULL; | |
767 | break; | |
768 | default: | |
b973cb7e | 769 | return NULL; |
69840466 | 770 | } |
d6d48196 | 771 | |
80a761fd TH |
772 | /* |
773 | * If failfast settings disagree or any of the two is already | |
774 | * a mixed merge, mark both as mixed before proceeding. This | |
775 | * makes sure that all involved bios have mixable attributes | |
776 | * set properly. | |
777 | */ | |
e8064021 | 778 | if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || |
80a761fd TH |
779 | (req->cmd_flags & REQ_FAILFAST_MASK) != |
780 | (next->cmd_flags & REQ_FAILFAST_MASK)) { | |
781 | blk_rq_set_mixed_merge(req); | |
782 | blk_rq_set_mixed_merge(next); | |
783 | } | |
784 | ||
d6d48196 | 785 | /* |
522a7775 OS |
786 | * At this point we have either done a back merge or front merge. We |
787 | * need the smaller start_time_ns of the merged requests to be the | |
788 | * current request for accounting purposes. | |
d6d48196 | 789 | */ |
522a7775 OS |
790 | if (next->start_time_ns < req->start_time_ns) |
791 | req->start_time_ns = next->start_time_ns; | |
d6d48196 JA |
792 | |
793 | req->biotail->bi_next = next->bio; | |
794 | req->biotail = next->biotail; | |
795 | ||
a2dec7b3 | 796 | req->__data_len += blk_rq_bytes(next); |
d6d48196 | 797 | |
2a5cf35c | 798 | if (!blk_discard_mergable(req)) |
445251d0 | 799 | elv_merge_requests(q, req, next); |
d6d48196 | 800 | |
42dad764 JM |
801 | /* |
802 | * 'next' is going away, so update stats accordingly | |
803 | */ | |
804 | blk_account_io_merge(next); | |
d6d48196 | 805 | |
e4d750c9 JA |
806 | /* |
807 | * ownership of bio passed from next to req, return 'next' for | |
808 | * the caller to free | |
809 | */ | |
1cd96c24 | 810 | next->bio = NULL; |
b973cb7e | 811 | return next; |
d6d48196 JA |
812 | } |
813 | ||
b973cb7e | 814 | struct request *attempt_back_merge(struct request_queue *q, struct request *rq) |
d6d48196 JA |
815 | { |
816 | struct request *next = elv_latter_request(q, rq); | |
817 | ||
818 | if (next) | |
819 | return attempt_merge(q, rq, next); | |
820 | ||
b973cb7e | 821 | return NULL; |
d6d48196 JA |
822 | } |
823 | ||
b973cb7e | 824 | struct request *attempt_front_merge(struct request_queue *q, struct request *rq) |
d6d48196 JA |
825 | { |
826 | struct request *prev = elv_former_request(q, rq); | |
827 | ||
828 | if (prev) | |
829 | return attempt_merge(q, prev, rq); | |
830 | ||
b973cb7e | 831 | return NULL; |
d6d48196 | 832 | } |
5e84ea3a JA |
833 | |
834 | int blk_attempt_req_merge(struct request_queue *q, struct request *rq, | |
835 | struct request *next) | |
836 | { | |
e4d750c9 | 837 | struct request *free; |
72ef799b | 838 | |
e4d750c9 JA |
839 | free = attempt_merge(q, rq, next); |
840 | if (free) { | |
92bc5a24 | 841 | blk_put_request(free); |
e4d750c9 JA |
842 | return 1; |
843 | } | |
844 | ||
845 | return 0; | |
5e84ea3a | 846 | } |
050c8ea8 TH |
847 | |
848 | bool blk_rq_merge_ok(struct request *rq, struct bio *bio) | |
849 | { | |
e2a60da7 | 850 | if (!rq_mergeable(rq) || !bio_mergeable(bio)) |
050c8ea8 TH |
851 | return false; |
852 | ||
288dab8a | 853 | if (req_op(rq) != bio_op(bio)) |
f31dc1cd MP |
854 | return false; |
855 | ||
050c8ea8 TH |
856 | /* different data direction or already started, don't merge */ |
857 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
858 | return false; | |
859 | ||
2081a56b JA |
860 | /* must be same device */ |
861 | if (rq->rq_disk != bio->bi_disk) | |
050c8ea8 TH |
862 | return false; |
863 | ||
864 | /* only merge integrity protected bio into ditto rq */ | |
4eaf99be | 865 | if (blk_integrity_merge_bio(rq->q, rq, bio) == false) |
050c8ea8 TH |
866 | return false; |
867 | ||
4363ac7c | 868 | /* must be using the same buffer */ |
8fe0d473 | 869 | if (req_op(rq) == REQ_OP_WRITE_SAME && |
4363ac7c MP |
870 | !blk_write_same_mergeable(rq->bio, bio)) |
871 | return false; | |
872 | ||
cb6934f8 JA |
873 | /* |
874 | * Don't allow merge of different write hints, or for a hint with | |
875 | * non-hint IO. | |
876 | */ | |
877 | if (rq->write_hint != bio->bi_write_hint) | |
878 | return false; | |
879 | ||
668ffc03 DLM |
880 | if (rq->ioprio != bio_prio(bio)) |
881 | return false; | |
882 | ||
050c8ea8 TH |
883 | return true; |
884 | } | |
885 | ||
34fe7c05 | 886 | enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) |
050c8ea8 | 887 | { |
69840466 | 888 | if (blk_discard_mergable(rq)) |
1e739730 CH |
889 | return ELEVATOR_DISCARD_MERGE; |
890 | else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) | |
050c8ea8 | 891 | return ELEVATOR_BACK_MERGE; |
4f024f37 | 892 | else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) |
050c8ea8 TH |
893 | return ELEVATOR_FRONT_MERGE; |
894 | return ELEVATOR_NO_MERGE; | |
895 | } |