Branch data Line data Source code
1 : : // SPDX-License-Identifier: GPL-2.0
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 : :
11 : : #include <trace/events/block.h>
12 : :
13 : : #include "blk.h"
14 : :
15 : 1670 : static inline bool bio_will_gap(struct request_queue *q,
16 : : struct request *prev_rq, struct bio *prev, struct bio *next)
17 : : {
18 : 1670 : struct bio_vec pb, nb;
19 : :
20 [ + - - + ]: 3340 : 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 [ # # ]: 0 : if (prev_rq)
29 : 0 : bio_get_first_bvec(prev_rq->bio, &pb);
30 : : else
31 : 0 : bio_get_first_bvec(prev, &pb);
32 [ # # ]: 0 : if (pb.bv_offset & queue_virt_boundary(q))
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 : 0 : bio_get_last_bvec(prev, &pb);
45 : 0 : bio_get_first_bvec(next, &nb);
46 [ # # ]: 0 : if (biovec_phys_mergeable(q, &pb, &nb))
47 : : return false;
48 [ # # ]: 0 : return __bvec_gap_to_prev(q, &pb, nb.bv_offset);
49 : : }
50 : :
51 : 1625 : static inline bool req_gap_back_merge(struct request *req, struct bio *bio)
52 : : {
53 : 1625 : return bio_will_gap(req->q, req, req->biotail, bio);
54 : : }
55 : :
56 : 45 : static inline bool req_gap_front_merge(struct request *req, struct bio *bio)
57 : : {
58 : 45 : return bio_will_gap(req->q, NULL, bio, req->bio);
59 : : }
60 : :
61 : 0 : static struct bio *blk_bio_discard_split(struct request_queue *q,
62 : : struct bio *bio,
63 : : struct bio_set *bs,
64 : : unsigned *nsegs)
65 : : {
66 : 0 : unsigned int max_discard_sectors, granularity;
67 : 0 : int alignment;
68 : 0 : sector_t tmp;
69 : 0 : unsigned split_sectors;
70 : :
71 : 0 : *nsegs = 1;
72 : :
73 : : /* Zero-sector (unknown) and one-sector granularities are the same. */
74 : 0 : granularity = max(q->limits.discard_granularity >> 9, 1U);
75 : :
76 [ # # ]: 0 : max_discard_sectors = min(q->limits.max_discard_sectors,
77 : : bio_allowed_max_sectors(q));
78 : 0 : max_discard_sectors -= max_discard_sectors % granularity;
79 : :
80 [ # # ]: 0 : if (unlikely(!max_discard_sectors)) {
81 : : /* XXX: warn */
82 : : return NULL;
83 : : }
84 : :
85 [ # # ]: 0 : if (bio_sectors(bio) <= max_discard_sectors)
86 : : return NULL;
87 : :
88 : 0 : 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 : 0 : alignment = (q->limits.discard_alignment >> 9) % granularity;
95 : :
96 : 0 : tmp = bio->bi_iter.bi_sector + split_sectors - alignment;
97 : 0 : tmp = sector_div(tmp, granularity);
98 : :
99 [ # # ]: 0 : if (split_sectors > tmp)
100 : 0 : split_sectors -= tmp;
101 : :
102 : 0 : return bio_split(bio, split_sectors, GFP_NOIO, bs);
103 : : }
104 : :
105 : 0 : static struct bio *blk_bio_write_zeroes_split(struct request_queue *q,
106 : : struct bio *bio, struct bio_set *bs, unsigned *nsegs)
107 : : {
108 : 0 : *nsegs = 0;
109 : :
110 : 0 : if (!q->limits.max_write_zeroes_sectors)
111 : : return NULL;
112 : :
113 [ # # ]: 0 : if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors)
114 : : return NULL;
115 : :
116 : 0 : return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs);
117 : : }
118 : :
119 : 0 : static struct bio *blk_bio_write_same_split(struct request_queue *q,
120 : : struct bio *bio,
121 : : struct bio_set *bs,
122 : : unsigned *nsegs)
123 : : {
124 : 0 : *nsegs = 1;
125 : :
126 : 0 : if (!q->limits.max_write_same_sectors)
127 : : return NULL;
128 : :
129 [ # # ]: 0 : if (bio_sectors(bio) <= q->limits.max_write_same_sectors)
130 : : return NULL;
131 : :
132 : 0 : return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs);
133 : : }
134 : :
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 : : */
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);
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);
151 : :
152 : : max_sectors += start_offset;
153 : : max_sectors &= ~(pbs - 1);
154 : : if (max_sectors > start_offset)
155 : : return max_sectors - start_offset;
156 : :
157 : : return sectors & (lbs - 1);
158 : : }
159 : :
160 : 5484 : static inline unsigned get_max_segment_size(const struct request_queue *q,
161 : : struct page *start_page,
162 : : unsigned long offset)
163 : : {
164 : 5484 : unsigned long mask = queue_segment_boundary(q);
165 : :
166 : 5484 : offset = mask & (page_to_phys(start_page) + offset);
167 : :
168 : : /*
169 : : * overflow may be triggered in case of zero page physical address
170 : : * on 32bit arch, use queue's max segment size when that happens.
171 : : */
172 [ + - + - : 5484 : return min_not_zero(mask - offset + 1,
+ - + - ]
173 : : (unsigned long)queue_max_segment_size(q));
174 : : }
175 : :
176 : : /**
177 : : * bvec_split_segs - verify whether or not a bvec should be split in the middle
178 : : * @q: [in] request queue associated with the bio associated with @bv
179 : : * @bv: [in] bvec to examine
180 : : * @nsegs: [in,out] Number of segments in the bio being built. Incremented
181 : : * by the number of segments from @bv that may be appended to that
182 : : * bio without exceeding @max_segs
183 : : * @sectors: [in,out] Number of sectors in the bio being built. Incremented
184 : : * by the number of sectors from @bv that may be appended to that
185 : : * bio without exceeding @max_sectors
186 : : * @max_segs: [in] upper bound for *@nsegs
187 : : * @max_sectors: [in] upper bound for *@sectors
188 : : *
189 : : * When splitting a bio, it can happen that a bvec is encountered that is too
190 : : * big to fit in a single segment and hence that it has to be split in the
191 : : * middle. This function verifies whether or not that should happen. The value
192 : : * %true is returned if and only if appending the entire @bv to a bio with
193 : : * *@nsegs segments and *@sectors sectors would make that bio unacceptable for
194 : : * the block driver.
195 : : */
196 : 1748 : static bool bvec_split_segs(const struct request_queue *q,
197 : : const struct bio_vec *bv, unsigned *nsegs,
198 : : unsigned *sectors, unsigned max_segs,
199 : : unsigned max_sectors)
200 : : {
201 : 1748 : unsigned max_len = (min(max_sectors, UINT_MAX >> 9) - *sectors) << 9;
202 : 1748 : unsigned len = min(bv->bv_len, max_len);
203 : 1748 : unsigned total_len = 0;
204 : 1748 : unsigned seg_size = 0;
205 : :
206 [ + + + - ]: 4490 : while (len && *nsegs < max_segs) {
207 : 2742 : seg_size = get_max_segment_size(q, bv->bv_page,
208 [ + - ]: 2742 : bv->bv_offset + total_len);
209 : 2742 : seg_size = min(seg_size, len);
210 : :
211 : 2742 : (*nsegs)++;
212 : 2742 : total_len += seg_size;
213 : 2742 : len -= seg_size;
214 : :
215 [ + - ]: 2742 : if ((bv->bv_offset + total_len) & queue_virt_boundary(q))
216 : : break;
217 : : }
218 : :
219 : 1748 : *sectors += total_len >> 9;
220 : :
221 : : /* tell the caller to split the bvec if it is too big to fit */
222 [ + - + - ]: 1748 : return len > 0 || bv->bv_len > max_len;
223 : : }
224 : :
225 : : /**
226 : : * blk_bio_segment_split - split a bio in two bios
227 : : * @q: [in] request queue pointer
228 : : * @bio: [in] bio to be split
229 : : * @bs: [in] bio set to allocate the clone from
230 : : * @segs: [out] number of segments in the bio with the first half of the sectors
231 : : *
232 : : * Clone @bio, update the bi_iter of the clone to represent the first sectors
233 : : * of @bio and update @bio->bi_iter to represent the remaining sectors. The
234 : : * following is guaranteed for the cloned bio:
235 : : * - That it has at most get_max_io_size(@q, @bio) sectors.
236 : : * - That it has at most queue_max_segments(@q) segments.
237 : : *
238 : : * Except for discard requests the cloned bio will point at the bi_io_vec of
239 : : * the original bio. It is the responsibility of the caller to ensure that the
240 : : * original bio is not freed before the cloned bio. The caller is also
241 : : * responsible for ensuring that @bs is only destroyed after processing of the
242 : : * split bio has finished.
243 : : */
244 : 1554 : static struct bio *blk_bio_segment_split(struct request_queue *q,
245 : : struct bio *bio,
246 : : struct bio_set *bs,
247 : : unsigned *segs)
248 : : {
249 : 1554 : struct bio_vec bv, bvprv, *bvprvp = NULL;
250 : 1554 : struct bvec_iter iter;
251 : 1554 : unsigned nsegs = 0, sectors = 0;
252 : 1554 : const unsigned max_sectors = get_max_io_size(q, bio);
253 : 1554 : const unsigned max_segs = queue_max_segments(q);
254 : :
255 [ + + ]: 8525 : bio_for_each_bvec(bv, bio, iter) {
256 : : /*
257 : : * If the queue doesn't support SG gaps and adding this
258 : : * offset would create a gap, disallow it.
259 : : */
260 [ - - + + ]: 6971 : if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset))
261 : 0 : goto split;
262 : :
263 [ + - ]: 6971 : if (nsegs < max_segs &&
264 [ + - ]: 6971 : sectors + (bv.bv_len >> 9) <= max_sectors &&
265 [ + + ]: 6971 : bv.bv_offset + bv.bv_len <= PAGE_SIZE) {
266 : 5223 : nsegs++;
267 : 5223 : sectors += bv.bv_len >> 9;
268 [ - + ]: 1748 : } else if (bvec_split_segs(q, &bv, &nsegs, §ors, max_segs,
269 : : max_sectors)) {
270 : 0 : goto split;
271 : : }
272 : :
273 : 6971 : bvprv = bv;
274 : 6971 : bvprvp = &bvprv;
275 : : }
276 : :
277 : 1554 : *segs = nsegs;
278 : 1554 : return NULL;
279 : 0 : split:
280 : 0 : *segs = nsegs;
281 : 0 : return bio_split(bio, sectors, GFP_NOIO, bs);
282 : : }
283 : :
284 : : /**
285 : : * __blk_queue_split - split a bio and submit the second half
286 : : * @q: [in] request queue pointer
287 : : * @bio: [in, out] bio to be split
288 : : * @nr_segs: [out] number of segments in the first bio
289 : : *
290 : : * Split a bio into two bios, chain the two bios, submit the second half and
291 : : * store a pointer to the first half in *@bio. If the second bio is still too
292 : : * big it will be split by a recursive call to this function. Since this
293 : : * function may allocate a new bio from @q->bio_split, it is the responsibility
294 : : * of the caller to ensure that @q is only released after processing of the
295 : : * split bio has finished.
296 : : */
297 : 4584 : void __blk_queue_split(struct request_queue *q, struct bio **bio,
298 : : unsigned int *nr_segs)
299 : : {
300 : 4584 : struct bio *split = NULL;
301 : :
302 [ - - - + ]: 4584 : switch (bio_op(*bio)) {
303 : 0 : case REQ_OP_DISCARD:
304 : : case REQ_OP_SECURE_ERASE:
305 : 0 : split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs);
306 : 0 : break;
307 : 0 : case REQ_OP_WRITE_ZEROES:
308 [ # # ]: 0 : split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split,
309 : : nr_segs);
310 : 0 : break;
311 : 0 : case REQ_OP_WRITE_SAME:
312 [ # # ]: 0 : split = blk_bio_write_same_split(q, *bio, &q->bio_split,
313 : : nr_segs);
314 : 0 : break;
315 : 4584 : default:
316 : : /*
317 : : * All drivers must accept single-segments bios that are <=
318 : : * PAGE_SIZE. This is a quick and dirty check that relies on
319 : : * the fact that bi_io_vec[0] is always valid if a bio has data.
320 : : * The check might lead to occasional false negatives when bios
321 : : * are cloned, but compared to the performance impact of cloned
322 : : * bios themselves the loop below doesn't matter anyway.
323 : : */
324 [ + - ]: 4584 : if (!q->limits.chunk_sectors &&
325 [ + + ]: 4584 : (*bio)->bi_vcnt == 1 &&
326 : 3923 : ((*bio)->bi_io_vec[0].bv_len +
327 [ + + ]: 3923 : (*bio)->bi_io_vec[0].bv_offset) <= PAGE_SIZE) {
328 : 3030 : *nr_segs = 1;
329 : 3030 : break;
330 : : }
331 : 1554 : split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs);
332 : 1554 : break;
333 : : }
334 : :
335 [ - + ]: 4584 : if (split) {
336 : : /* there isn't chance to merge the splitted bio */
337 : 0 : split->bi_opf |= REQ_NOMERGE;
338 : :
339 : : /*
340 : : * Since we're recursing into make_request here, ensure
341 : : * that we mark this bio as already having entered the queue.
342 : : * If not, and the queue is going away, we can get stuck
343 : : * forever on waiting for the queue reference to drop. But
344 : : * that will never happen, as we're already holding a
345 : : * reference to it.
346 : : */
347 : 0 : bio_set_flag(*bio, BIO_QUEUE_ENTERED);
348 : :
349 : 0 : bio_chain(split, *bio);
350 : 0 : trace_block_split(q, split, (*bio)->bi_iter.bi_sector);
351 : 0 : generic_make_request(*bio);
352 : 0 : *bio = split;
353 : : }
354 : 4584 : }
355 : :
356 : : /**
357 : : * blk_queue_split - split a bio and submit the second half
358 : : * @q: [in] request queue pointer
359 : : * @bio: [in, out] bio to be split
360 : : *
361 : : * Split a bio into two bios, chains the two bios, submit the second half and
362 : : * store a pointer to the first half in *@bio. Since this function may allocate
363 : : * a new bio from @q->bio_split, it is the responsibility of the caller to
364 : : * ensure that @q is only released after processing of the split bio has
365 : : * finished.
366 : : */
367 : 0 : void blk_queue_split(struct request_queue *q, struct bio **bio)
368 : : {
369 : 0 : unsigned int nr_segs;
370 : :
371 : 0 : __blk_queue_split(q, bio, &nr_segs);
372 : 0 : }
373 : : EXPORT_SYMBOL(blk_queue_split);
374 : :
375 : 0 : unsigned int blk_recalc_rq_segments(struct request *rq)
376 : : {
377 : 0 : unsigned int nr_phys_segs = 0;
378 : 0 : unsigned int nr_sectors = 0;
379 : 0 : struct req_iterator iter;
380 : 0 : struct bio_vec bv;
381 : :
382 [ # # ]: 0 : if (!rq->bio)
383 : : return 0;
384 : :
385 [ # # # ]: 0 : switch (bio_op(rq->bio)) {
386 : : case REQ_OP_DISCARD:
387 : : case REQ_OP_SECURE_ERASE:
388 : : case REQ_OP_WRITE_ZEROES:
389 : : return 0;
390 : 0 : case REQ_OP_WRITE_SAME:
391 : 0 : return 1;
392 : : }
393 : :
394 [ # # # # ]: 0 : rq_for_each_bvec(bv, rq, iter)
395 : 0 : bvec_split_segs(rq->q, &bv, &nr_phys_segs, &nr_sectors,
396 : : UINT_MAX, UINT_MAX);
397 : 0 : return nr_phys_segs;
398 : : }
399 : :
400 : 10931 : static inline struct scatterlist *blk_next_sg(struct scatterlist **sg,
401 : : struct scatterlist *sglist)
402 : : {
403 : 10931 : if (!*sg)
404 : : return sglist;
405 : :
406 : : /*
407 : : * If the driver previously mapped a shorter list, we could see a
408 : : * termination bit prematurely unless it fully inits the sg table
409 : : * on each mapping. We KNOW that there must be more entries here
410 : : * or the driver would be buggy, so force clear the termination bit
411 : : * to avoid doing a full sg_init_table() in drivers for each command.
412 : : */
413 : 7663 : sg_unmark_end(*sg);
414 : 7663 : return sg_next(*sg);
415 : : }
416 : :
417 : 1748 : static unsigned blk_bvec_map_sg(struct request_queue *q,
418 : : struct bio_vec *bvec, struct scatterlist *sglist,
419 : : struct scatterlist **sg)
420 : : {
421 : 1748 : unsigned nbytes = bvec->bv_len;
422 : 1748 : unsigned nsegs = 0, total = 0;
423 : :
424 [ + + ]: 4490 : while (nbytes > 0) {
425 : 2742 : unsigned offset = bvec->bv_offset + total;
426 [ + - ]: 2742 : unsigned len = min(get_max_segment_size(q, bvec->bv_page,
427 : : offset), nbytes);
428 : 2742 : struct page *page = bvec->bv_page;
429 : :
430 : : /*
431 : : * Unfortunately a fair number of drivers barf on scatterlists
432 : : * that have an offset larger than PAGE_SIZE, despite other
433 : : * subsystems dealing with that invariant just fine. For now
434 : : * stick to the legacy format where we never present those from
435 : : * the block layer, but the code below should be removed once
436 : : * these offenders (mostly MMC/SD drivers) are fixed.
437 : : */
438 : 2742 : page += (offset >> PAGE_SHIFT);
439 : 2742 : offset &= ~PAGE_MASK;
440 : :
441 [ + + ]: 2742 : *sg = blk_next_sg(sg, sglist);
442 [ - + ]: 2742 : sg_set_page(*sg, page, len, offset);
443 : :
444 : 2742 : total += len;
445 : 2742 : nbytes -= len;
446 : 2742 : nsegs++;
447 : : }
448 : :
449 : 1748 : return nsegs;
450 : : }
451 : :
452 : 8189 : static inline int __blk_bvec_map_sg(struct bio_vec bv,
453 : : struct scatterlist *sglist, struct scatterlist **sg)
454 : : {
455 [ + + ]: 8189 : *sg = blk_next_sg(sg, sglist);
456 [ - + ]: 8189 : sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset);
457 : 8189 : return 1;
458 : : }
459 : :
460 : : /* only try to merge bvecs into one sg if they are from two bios */
461 : : static inline bool
462 : : __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec,
463 : : struct bio_vec *bvprv, struct scatterlist **sg)
464 : : {
465 : :
466 : : int nbytes = bvec->bv_len;
467 : :
468 : : if (!*sg)
469 : : return false;
470 : :
471 : : if ((*sg)->length + nbytes > queue_max_segment_size(q))
472 : : return false;
473 : :
474 : : if (!biovec_phys_mergeable(q, bvprv, bvec))
475 : : return false;
476 : :
477 : : (*sg)->length += nbytes;
478 : :
479 : : return true;
480 : : }
481 : :
482 : 3268 : static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio,
483 : : struct scatterlist *sglist,
484 : : struct scatterlist **sg)
485 : : {
486 : 3268 : struct bio_vec uninitialized_var(bvec), bvprv = { NULL };
487 : 3268 : struct bvec_iter iter;
488 : 3268 : int nsegs = 0;
489 : 3268 : bool new_bio = false;
490 : :
491 [ + + ]: 8206 : for_each_bio(bio) {
492 [ + + ]: 15293 : bio_for_each_bvec(bvec, bio, iter) {
493 : : /*
494 : : * Only try to merge bvecs from two bios given we
495 : : * have done bio internal merge when adding pages
496 : : * to bio
497 : : */
498 [ + + + + ]: 12025 : if (new_bio &&
499 : 1670 : __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg))
500 : 418 : goto next_bvec;
501 : :
502 [ + + ]: 9937 : if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE)
503 : 8189 : nsegs += __blk_bvec_map_sg(bvec, sglist, sg);
504 : : else
505 : 1748 : nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg);
506 : 10355 : next_bvec:
507 : 10355 : new_bio = false;
508 : : }
509 [ + - ]: 4938 : if (likely(bio->bi_iter.bi_size)) {
510 : 4938 : bvprv = bvec;
511 : 4938 : new_bio = true;
512 : : }
513 : : }
514 : :
515 : 3268 : return nsegs;
516 : : }
517 : :
518 : : /*
519 : : * map a request to scatterlist, return number of sg entries setup. Caller
520 : : * must make sure sg can hold rq->nr_phys_segments entries
521 : : */
522 : 3268 : int blk_rq_map_sg(struct request_queue *q, struct request *rq,
523 : : struct scatterlist *sglist)
524 : : {
525 : 3268 : struct scatterlist *sg = NULL;
526 : 3268 : int nsegs = 0;
527 : :
528 [ - + ]: 3268 : if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
529 : 0 : nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, &sg);
530 [ + - - + ]: 3268 : else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME)
531 : 0 : nsegs = __blk_bvec_map_sg(bio_iovec(rq->bio), sglist, &sg);
532 [ + - ]: 3268 : else if (rq->bio)
533 : 3268 : nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg);
534 : :
535 [ + + + + ]: 3268 : if (unlikely(rq->rq_flags & RQF_COPY_USER) &&
536 [ + + ]: 285 : (blk_rq_bytes(rq) & q->dma_pad_mask)) {
537 : 9 : unsigned int pad_len =
538 : 9 : (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1;
539 : :
540 : 9 : sg->length += pad_len;
541 : 9 : rq->extra_len += pad_len;
542 : : }
543 : :
544 [ + + + + ]: 3268 : if (q->dma_drain_size && q->dma_drain_needed(rq)) {
545 [ - + ]: 54 : if (op_is_write(req_op(rq)))
546 : 0 : memset(q->dma_drain_buffer, 0, q->dma_drain_size);
547 : :
548 : 54 : sg_unmark_end(sg);
549 : 54 : sg = sg_next(sg);
550 [ - + ]: 54 : sg_set_page(sg, virt_to_page(q->dma_drain_buffer),
551 : : q->dma_drain_size,
552 [ + - ]: 54 : ((unsigned long)q->dma_drain_buffer) &
553 : : (PAGE_SIZE - 1));
554 : 54 : nsegs++;
555 : 54 : rq->extra_len += q->dma_drain_size;
556 : : }
557 : :
558 [ + - ]: 3268 : if (sg)
559 : 3268 : sg_mark_end(sg);
560 : :
561 : : /*
562 : : * Something must have been wrong if the figured number of
563 : : * segment is bigger than number of req's physical segments
564 : : */
565 [ + - - + ]: 6536 : WARN_ON(nsegs > blk_rq_nr_phys_segments(rq));
566 : :
567 : 3268 : return nsegs;
568 : : }
569 : : EXPORT_SYMBOL(blk_rq_map_sg);
570 : :
571 : 1634 : static inline int ll_new_hw_segment(struct request *req, struct bio *bio,
572 : : unsigned int nr_phys_segs)
573 : : {
574 : 1634 : if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(req->q))
575 : 0 : goto no_merge;
576 : :
577 : 1634 : if (blk_integrity_merge_bio(req->q, req, bio) == false)
578 : : goto no_merge;
579 : :
580 : : /*
581 : : * This will form the start of a new hw segment. Bump both
582 : : * counters.
583 : : */
584 : 1634 : req->nr_phys_segments += nr_phys_segs;
585 : 1634 : return 1;
586 : :
587 : : no_merge:
588 [ # # # # ]: 0 : req_set_nomerge(req->q, req);
589 : : return 0;
590 : : }
591 : :
592 : 1589 : int ll_back_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs)
593 : : {
594 [ + - ]: 1589 : if (req_gap_back_merge(req, bio))
595 : : return 0;
596 [ - + ]: 1589 : if (blk_integrity_rq(req) &&
597 : : integrity_req_gap_back_merge(req, bio))
598 : : return 0;
599 [ - + ]: 1589 : if (blk_rq_sectors(req) + bio_sectors(bio) >
600 [ - + ]: 1589 : blk_rq_get_max_sectors(req, blk_rq_pos(req))) {
601 [ # # ]: 0 : req_set_nomerge(req->q, req);
602 : 0 : return 0;
603 : : }
604 : :
605 [ - + ]: 1589 : return ll_new_hw_segment(req, bio, nr_segs);
606 : : }
607 : :
608 : 45 : int ll_front_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs)
609 : : {
610 [ + - ]: 45 : if (req_gap_front_merge(req, bio))
611 : : return 0;
612 [ - + ]: 45 : if (blk_integrity_rq(req) &&
613 : : integrity_req_gap_front_merge(req, bio))
614 : : return 0;
615 [ - + ]: 45 : if (blk_rq_sectors(req) + bio_sectors(bio) >
616 [ - + ]: 45 : blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) {
617 [ # # ]: 0 : req_set_nomerge(req->q, req);
618 : 0 : return 0;
619 : : }
620 : :
621 [ - + ]: 45 : return ll_new_hw_segment(req, bio, nr_segs);
622 : : }
623 : :
624 : 0 : static bool req_attempt_discard_merge(struct request_queue *q, struct request *req,
625 : : struct request *next)
626 : : {
627 [ # # ]: 0 : unsigned short segments = blk_rq_nr_discard_segments(req);
628 : :
629 [ # # ]: 0 : if (segments >= queue_max_discard_segments(q))
630 : 0 : goto no_merge;
631 [ # # ]: 0 : if (blk_rq_sectors(req) + bio_sectors(next->bio) >
632 [ # # ]: 0 : blk_rq_get_max_sectors(req, blk_rq_pos(req)))
633 : 0 : goto no_merge;
634 : :
635 : 0 : req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next);
636 : 0 : return true;
637 : 0 : no_merge:
638 [ # # ]: 0 : req_set_nomerge(q, req);
639 : : return false;
640 : : }
641 : :
642 : 36 : static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
643 : : struct request *next)
644 : : {
645 : 36 : int total_phys_segments;
646 : :
647 [ + - ]: 36 : if (req_gap_back_merge(req, next->bio))
648 : : return 0;
649 : :
650 : : /*
651 : : * Will it become too large?
652 : : */
653 [ + - ]: 36 : if ((blk_rq_sectors(req) + blk_rq_sectors(next)) >
654 [ + - ]: 36 : blk_rq_get_max_sectors(req, blk_rq_pos(req)))
655 : : return 0;
656 : :
657 : 36 : total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
658 [ + - ]: 36 : if (total_phys_segments > queue_max_segments(q))
659 : : return 0;
660 : :
661 : 36 : if (blk_integrity_merge_rq(q, req, next) == false)
662 : : return 0;
663 : :
664 : : /* Merge is OK... */
665 : 36 : req->nr_phys_segments = total_phys_segments;
666 : 36 : return 1;
667 : : }
668 : :
669 : : /**
670 : : * blk_rq_set_mixed_merge - mark a request as mixed merge
671 : : * @rq: request to mark as mixed merge
672 : : *
673 : : * Description:
674 : : * @rq is about to be mixed merged. Make sure the attributes
675 : : * which can be mixed are set in each bio and mark @rq as mixed
676 : : * merged.
677 : : */
678 : 1444 : void blk_rq_set_mixed_merge(struct request *rq)
679 : : {
680 : 1444 : unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
681 : 1444 : struct bio *bio;
682 : :
683 [ + + ]: 1444 : if (rq->rq_flags & RQF_MIXED_MERGE)
684 : : return;
685 : :
686 : : /*
687 : : * @rq will no longer represent mixable attributes for all the
688 : : * contained bios. It will just track those of the first one.
689 : : * Distributes the attributs to each bio.
690 : : */
691 [ + + ]: 170 : for (bio = rq->bio; bio; bio = bio->bi_next) {
692 [ - + - - : 170 : WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) &&
- + ]
693 : : (bio->bi_opf & REQ_FAILFAST_MASK) != ff);
694 : 85 : bio->bi_opf |= ff;
695 : : }
696 : 85 : rq->rq_flags |= RQF_MIXED_MERGE;
697 : : }
698 : :
699 : 36 : static void blk_account_io_merge(struct request *req)
700 : : {
701 [ + - + - ]: 72 : if (blk_do_io_stat(req)) {
702 : 36 : struct hd_struct *part;
703 : :
704 : 36 : part_stat_lock();
705 : 36 : part = req->part;
706 : :
707 : 36 : part_dec_in_flight(req->q, part, rq_data_dir(req));
708 : :
709 : 36 : hd_struct_put(part);
710 : 36 : part_stat_unlock();
711 : : }
712 : 36 : }
713 : : /*
714 : : * Two cases of handling DISCARD merge:
715 : : * If max_discard_segments > 1, the driver takes every bio
716 : : * as a range and send them to controller together. The ranges
717 : : * needn't to be contiguous.
718 : : * Otherwise, the bios/requests will be handled as same as
719 : : * others which should be contiguous.
720 : : */
721 : 1824 : static inline bool blk_discard_mergable(struct request *req)
722 : : {
723 [ # # # # : 0 : if (req_op(req) == REQ_OP_DISCARD &&
# # ]
724 [ # # # # : 0 : queue_max_discard_segments(req->q) > 1)
# # ]
725 : : return true;
726 : : return false;
727 : : }
728 : :
729 : 51 : static enum elv_merge blk_try_req_merge(struct request *req,
730 : : struct request *next)
731 : : {
732 : 51 : if (blk_discard_mergable(req))
733 : : return ELEVATOR_DISCARD_MERGE;
734 [ + + ]: 51 : else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next))
735 : 36 : return ELEVATOR_BACK_MERGE;
736 : :
737 : : return ELEVATOR_NO_MERGE;
738 : : }
739 : :
740 : : /*
741 : : * For non-mq, this has to be called with the request spinlock acquired.
742 : : * For mq with scheduling, the appropriate queue wide lock should be held.
743 : : */
744 : 51 : static struct request *attempt_merge(struct request_queue *q,
745 : : struct request *req, struct request *next)
746 : : {
747 [ + - + - ]: 51 : if (!rq_mergeable(req) || !rq_mergeable(next))
748 : : return NULL;
749 : :
750 [ + - ]: 51 : if (req_op(req) != req_op(next))
751 : : return NULL;
752 : :
753 [ + - ]: 51 : if (rq_data_dir(req) != rq_data_dir(next)
754 [ + - ]: 51 : || req->rq_disk != next->rq_disk)
755 : : return NULL;
756 : :
757 [ - + ]: 51 : if (req_op(req) == REQ_OP_WRITE_SAME &&
758 [ # # ]: 0 : !blk_write_same_mergeable(req->bio, next->bio))
759 : : return NULL;
760 : :
761 : : /*
762 : : * Don't allow merge of different write hints, or for a hint with
763 : : * non-hint IO.
764 : : */
765 [ + - ]: 51 : if (req->write_hint != next->write_hint)
766 : : return NULL;
767 : :
768 [ + - ]: 51 : if (req->ioprio != next->ioprio)
769 : : return NULL;
770 : :
771 : : /*
772 : : * If we are allowed to merge, then append bio list
773 : : * from next to rq and release next. merge_requests_fn
774 : : * will have updated segment counts, update sector
775 : : * counts here. Handle DISCARDs separately, as they
776 : : * have separate settings.
777 : : */
778 : :
779 [ - + - + : 102 : switch (blk_try_req_merge(req, next)) {
+ ]
780 : 0 : case ELEVATOR_DISCARD_MERGE:
781 [ # # ]: 0 : if (!req_attempt_discard_merge(q, req, next))
782 : : return NULL;
783 : : break;
784 : 36 : case ELEVATOR_BACK_MERGE:
785 [ + - ]: 36 : if (!ll_merge_requests_fn(q, req, next))
786 : : return NULL;
787 : : break;
788 : : default:
789 : : return NULL;
790 : : }
791 : :
792 : : /*
793 : : * If failfast settings disagree or any of the two is already
794 : : * a mixed merge, mark both as mixed before proceeding. This
795 : : * makes sure that all involved bios have mixable attributes
796 : : * set properly.
797 : : */
798 [ - + ]: 36 : if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) ||
799 : 0 : (req->cmd_flags & REQ_FAILFAST_MASK) !=
800 [ # # ]: 0 : (next->cmd_flags & REQ_FAILFAST_MASK)) {
801 : 36 : blk_rq_set_mixed_merge(req);
802 : 36 : blk_rq_set_mixed_merge(next);
803 : : }
804 : :
805 : : /*
806 : : * At this point we have either done a back merge or front merge. We
807 : : * need the smaller start_time_ns of the merged requests to be the
808 : : * current request for accounting purposes.
809 : : */
810 [ - + ]: 36 : if (next->start_time_ns < req->start_time_ns)
811 : 0 : req->start_time_ns = next->start_time_ns;
812 : :
813 : 36 : req->biotail->bi_next = next->bio;
814 : 36 : req->biotail = next->biotail;
815 : :
816 [ - + ]: 36 : req->__data_len += blk_rq_bytes(next);
817 : :
818 [ - + ]: 36 : if (!blk_discard_mergable(req))
819 : 36 : elv_merge_requests(q, req, next);
820 : :
821 : : /*
822 : : * 'next' is going away, so update stats accordingly
823 : : */
824 : 36 : blk_account_io_merge(next);
825 : :
826 : : /*
827 : : * ownership of bio passed from next to req, return 'next' for
828 : : * the caller to free
829 : : */
830 : 36 : next->bio = NULL;
831 : 36 : return next;
832 : : }
833 : :
834 : 1 : struct request *attempt_back_merge(struct request_queue *q, struct request *rq)
835 : : {
836 : 1 : struct request *next = elv_latter_request(q, rq);
837 : :
838 [ - + ]: 1 : if (next)
839 : 0 : return attempt_merge(q, rq, next);
840 : :
841 : : return NULL;
842 : : }
843 : :
844 : 0 : struct request *attempt_front_merge(struct request_queue *q, struct request *rq)
845 : : {
846 : 0 : struct request *prev = elv_former_request(q, rq);
847 : :
848 [ # # ]: 0 : if (prev)
849 : 0 : return attempt_merge(q, prev, rq);
850 : :
851 : : return NULL;
852 : : }
853 : :
854 : 51 : int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
855 : : struct request *next)
856 : : {
857 : 51 : struct request *free;
858 : :
859 : 51 : free = attempt_merge(q, rq, next);
860 [ + + ]: 51 : if (free) {
861 : 36 : blk_put_request(free);
862 : 36 : return 1;
863 : : }
864 : :
865 : : return 0;
866 : : }
867 : :
868 : 1738 : bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
869 : : {
870 [ + - + - ]: 1738 : if (!rq_mergeable(rq) || !bio_mergeable(bio))
871 : : return false;
872 : :
873 [ + - ]: 1738 : if (req_op(rq) != bio_op(bio))
874 : : return false;
875 : :
876 : : /* different data direction or already started, don't merge */
877 [ + - ]: 1738 : if (bio_data_dir(bio) != rq_data_dir(rq))
878 : : return false;
879 : :
880 : : /* must be same device */
881 [ + - ]: 1738 : if (rq->rq_disk != bio->bi_disk)
882 : : return false;
883 : :
884 : : /* only merge integrity protected bio into ditto rq */
885 [ - + ]: 1738 : if (blk_integrity_merge_bio(rq->q, rq, bio) == false)
886 : : return false;
887 : :
888 : : /* must be using the same buffer */
889 [ - + ]: 1738 : if (req_op(rq) == REQ_OP_WRITE_SAME &&
890 [ # # ]: 0 : !blk_write_same_mergeable(rq->bio, bio))
891 : : return false;
892 : :
893 : : /*
894 : : * Don't allow merge of different write hints, or for a hint with
895 : : * non-hint IO.
896 : : */
897 [ + - ]: 1738 : if (rq->write_hint != bio->bi_write_hint)
898 : : return false;
899 : :
900 [ - + ]: 1738 : if (rq->ioprio != bio_prio(bio))
901 : 0 : return false;
902 : :
903 : : return true;
904 : : }
905 : :
906 : 1737 : enum elv_merge blk_try_merge(struct request *rq, struct bio *bio)
907 : : {
908 [ - + ]: 1737 : if (blk_discard_mergable(rq))
909 : : return ELEVATOR_DISCARD_MERGE;
910 [ + + ]: 1737 : else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
911 : : return ELEVATOR_BACK_MERGE;
912 [ + + ]: 149 : else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector)
913 : 45 : return ELEVATOR_FRONT_MERGE;
914 : : return ELEVATOR_NO_MERGE;
915 : : }
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