1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0
2d6d48196SJens Axboe /*
3d6d48196SJens Axboe * Functions related to segment and merge handling
4d6d48196SJens Axboe */
5d6d48196SJens Axboe #include <linux/kernel.h>
6d6d48196SJens Axboe #include <linux/module.h>
7d6d48196SJens Axboe #include <linux/bio.h>
8d6d48196SJens Axboe #include <linux/blkdev.h>
9fe45e630SChristoph Hellwig #include <linux/blk-integrity.h>
10d6d48196SJens Axboe #include <linux/scatterlist.h>
1182d981d4SChristoph Hellwig #include <linux/part_stat.h>
126b2b0459STejun Heo #include <linux/blk-cgroup.h>
13d6d48196SJens Axboe
14cda22646SMike Krinkin #include <trace/events/block.h>
15cda22646SMike Krinkin
16d6d48196SJens Axboe #include "blk.h"
172aa7745bSChristoph Hellwig #include "blk-mq-sched.h"
188e756373SBaolin Wang #include "blk-rq-qos.h"
19a7b36ee6SJens Axboe #include "blk-throttle.h"
20d6d48196SJens Axboe
bio_get_first_bvec(struct bio * bio,struct bio_vec * bv)21ff18d77bSChristoph Hellwig static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
22ff18d77bSChristoph Hellwig {
23ff18d77bSChristoph Hellwig *bv = mp_bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
24ff18d77bSChristoph Hellwig }
25ff18d77bSChristoph Hellwig
bio_get_last_bvec(struct bio * bio,struct bio_vec * bv)26ff18d77bSChristoph Hellwig static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
27ff18d77bSChristoph Hellwig {
28ff18d77bSChristoph Hellwig struct bvec_iter iter = bio->bi_iter;
29ff18d77bSChristoph Hellwig int idx;
30ff18d77bSChristoph Hellwig
31ff18d77bSChristoph Hellwig bio_get_first_bvec(bio, bv);
32ff18d77bSChristoph Hellwig if (bv->bv_len == bio->bi_iter.bi_size)
33ff18d77bSChristoph Hellwig return; /* this bio only has a single bvec */
34ff18d77bSChristoph Hellwig
35ff18d77bSChristoph Hellwig bio_advance_iter(bio, &iter, iter.bi_size);
36ff18d77bSChristoph Hellwig
37ff18d77bSChristoph Hellwig if (!iter.bi_bvec_done)
38ff18d77bSChristoph Hellwig idx = iter.bi_idx - 1;
39ff18d77bSChristoph Hellwig else /* in the middle of bvec */
40ff18d77bSChristoph Hellwig idx = iter.bi_idx;
41ff18d77bSChristoph Hellwig
42ff18d77bSChristoph Hellwig *bv = bio->bi_io_vec[idx];
43ff18d77bSChristoph Hellwig
44ff18d77bSChristoph Hellwig /*
45ff18d77bSChristoph Hellwig * iter.bi_bvec_done records actual length of the last bvec
46ff18d77bSChristoph Hellwig * if this bio ends in the middle of one io vector
47ff18d77bSChristoph Hellwig */
48ff18d77bSChristoph Hellwig if (iter.bi_bvec_done)
49ff18d77bSChristoph Hellwig bv->bv_len = iter.bi_bvec_done;
50ff18d77bSChristoph Hellwig }
51ff18d77bSChristoph Hellwig
bio_will_gap(struct request_queue * q,struct request * prev_rq,struct bio * prev,struct bio * next)52e9907009SChristoph Hellwig static inline bool bio_will_gap(struct request_queue *q,
53e9907009SChristoph Hellwig struct request *prev_rq, struct bio *prev, struct bio *next)
54e9907009SChristoph Hellwig {
55e9907009SChristoph Hellwig struct bio_vec pb, nb;
56e9907009SChristoph Hellwig
57e9907009SChristoph Hellwig if (!bio_has_data(prev) || !queue_virt_boundary(q))
58e9907009SChristoph Hellwig return false;
59e9907009SChristoph Hellwig
60e9907009SChristoph Hellwig /*
61e9907009SChristoph Hellwig * Don't merge if the 1st bio starts with non-zero offset, otherwise it
62e9907009SChristoph Hellwig * is quite difficult to respect the sg gap limit. We work hard to
63e9907009SChristoph Hellwig * merge a huge number of small single bios in case of mkfs.
64e9907009SChristoph Hellwig */
65e9907009SChristoph Hellwig if (prev_rq)
66e9907009SChristoph Hellwig bio_get_first_bvec(prev_rq->bio, &pb);
67e9907009SChristoph Hellwig else
68e9907009SChristoph Hellwig bio_get_first_bvec(prev, &pb);
69df376b2eSJohannes Thumshirn if (pb.bv_offset & queue_virt_boundary(q))
70e9907009SChristoph Hellwig return true;
71e9907009SChristoph Hellwig
72e9907009SChristoph Hellwig /*
73e9907009SChristoph Hellwig * We don't need to worry about the situation that the merged segment
74e9907009SChristoph Hellwig * ends in unaligned virt boundary:
75e9907009SChristoph Hellwig *
76e9907009SChristoph Hellwig * - if 'pb' ends aligned, the merged segment ends aligned
77e9907009SChristoph Hellwig * - if 'pb' ends unaligned, the next bio must include
78e9907009SChristoph Hellwig * one single bvec of 'nb', otherwise the 'nb' can't
79e9907009SChristoph Hellwig * merge with 'pb'
80e9907009SChristoph Hellwig */
81e9907009SChristoph Hellwig bio_get_last_bvec(prev, &pb);
82e9907009SChristoph Hellwig bio_get_first_bvec(next, &nb);
83200a9affSChristoph Hellwig if (biovec_phys_mergeable(q, &pb, &nb))
84e9907009SChristoph Hellwig return false;
85c55ddd90SChristoph Hellwig return __bvec_gap_to_prev(&q->limits, &pb, nb.bv_offset);
86e9907009SChristoph Hellwig }
87e9907009SChristoph Hellwig
req_gap_back_merge(struct request * req,struct bio * bio)88e9907009SChristoph Hellwig static inline bool req_gap_back_merge(struct request *req, struct bio *bio)
89e9907009SChristoph Hellwig {
90e9907009SChristoph Hellwig return bio_will_gap(req->q, req, req->biotail, bio);
91e9907009SChristoph Hellwig }
92e9907009SChristoph Hellwig
req_gap_front_merge(struct request * req,struct bio * bio)93e9907009SChristoph Hellwig static inline bool req_gap_front_merge(struct request *req, struct bio *bio)
94e9907009SChristoph Hellwig {
95e9907009SChristoph Hellwig return bio_will_gap(req->q, NULL, bio, req->bio);
96e9907009SChristoph Hellwig }
97e9907009SChristoph Hellwig
98b6dc6198SChristoph Hellwig /*
99b6dc6198SChristoph Hellwig * The max size one bio can handle is UINT_MAX becasue bvec_iter.bi_size
100b6dc6198SChristoph Hellwig * is defined as 'unsigned int', meantime it has to be aligned to with the
101b6dc6198SChristoph Hellwig * logical block size, which is the minimum accepted unit by hardware.
102b6dc6198SChristoph Hellwig */
bio_allowed_max_sectors(const struct queue_limits * lim)103aa261f20SBart Van Assche static unsigned int bio_allowed_max_sectors(const struct queue_limits *lim)
104b6dc6198SChristoph Hellwig {
105c55ddd90SChristoph Hellwig return round_down(UINT_MAX, lim->logical_block_size) >> SECTOR_SHIFT;
106b6dc6198SChristoph Hellwig }
107b6dc6198SChristoph Hellwig
bio_split_discard(struct bio * bio,const struct queue_limits * lim,unsigned * nsegs,struct bio_set * bs)108aa261f20SBart Van Assche static struct bio *bio_split_discard(struct bio *bio,
109aa261f20SBart Van Assche const struct queue_limits *lim,
1105a97806fSChristoph Hellwig unsigned *nsegs, struct bio_set *bs)
11154efd50bSKent Overstreet {
11254efd50bSKent Overstreet unsigned int max_discard_sectors, granularity;
11354efd50bSKent Overstreet sector_t tmp;
11454efd50bSKent Overstreet unsigned split_sectors;
11554efd50bSKent Overstreet
116bdced438SMing Lei *nsegs = 1;
117bdced438SMing Lei
11854efd50bSKent Overstreet /* Zero-sector (unknown) and one-sector granularities are the same. */
119c55ddd90SChristoph Hellwig granularity = max(lim->discard_granularity >> 9, 1U);
12054efd50bSKent Overstreet
121c55ddd90SChristoph Hellwig max_discard_sectors =
122c55ddd90SChristoph Hellwig min(lim->max_discard_sectors, bio_allowed_max_sectors(lim));
12354efd50bSKent Overstreet max_discard_sectors -= max_discard_sectors % granularity;
12454efd50bSKent Overstreet
12554efd50bSKent Overstreet if (unlikely(!max_discard_sectors)) {
12654efd50bSKent Overstreet /* XXX: warn */
12754efd50bSKent Overstreet return NULL;
12854efd50bSKent Overstreet }
12954efd50bSKent Overstreet
13054efd50bSKent Overstreet if (bio_sectors(bio) <= max_discard_sectors)
13154efd50bSKent Overstreet return NULL;
13254efd50bSKent Overstreet
13354efd50bSKent Overstreet split_sectors = max_discard_sectors;
13454efd50bSKent Overstreet
13554efd50bSKent Overstreet /*
13654efd50bSKent Overstreet * If the next starting sector would be misaligned, stop the discard at
13754efd50bSKent Overstreet * the previous aligned sector.
13854efd50bSKent Overstreet */
139c55ddd90SChristoph Hellwig tmp = bio->bi_iter.bi_sector + split_sectors -
140c55ddd90SChristoph Hellwig ((lim->discard_alignment >> 9) % granularity);
14154efd50bSKent Overstreet tmp = sector_div(tmp, granularity);
14254efd50bSKent Overstreet
14354efd50bSKent Overstreet if (split_sectors > tmp)
14454efd50bSKent Overstreet split_sectors -= tmp;
14554efd50bSKent Overstreet
14654efd50bSKent Overstreet return bio_split(bio, split_sectors, GFP_NOIO, bs);
14754efd50bSKent Overstreet }
14854efd50bSKent Overstreet
bio_split_write_zeroes(struct bio * bio,const struct queue_limits * lim,unsigned * nsegs,struct bio_set * bs)1495a97806fSChristoph Hellwig static struct bio *bio_split_write_zeroes(struct bio *bio,
150aa261f20SBart Van Assche const struct queue_limits *lim,
151aa261f20SBart Van Assche unsigned *nsegs, struct bio_set *bs)
152885fa13fSChristoph Hellwig {
153d665e12aSChristoph Hellwig *nsegs = 0;
154c55ddd90SChristoph Hellwig if (!lim->max_write_zeroes_sectors)
155885fa13fSChristoph Hellwig return NULL;
156c55ddd90SChristoph Hellwig if (bio_sectors(bio) <= lim->max_write_zeroes_sectors)
157885fa13fSChristoph Hellwig return NULL;
158c55ddd90SChristoph Hellwig return bio_split(bio, lim->max_write_zeroes_sectors, GFP_NOIO, bs);
159885fa13fSChristoph Hellwig }
160885fa13fSChristoph Hellwig
1619cc5169cSBart Van Assche /*
1629cc5169cSBart Van Assche * Return the maximum number of sectors from the start of a bio that may be
1639cc5169cSBart Van Assche * submitted as a single request to a block device. If enough sectors remain,
1649cc5169cSBart Van Assche * align the end to the physical block size. Otherwise align the end to the
1659cc5169cSBart Van Assche * logical block size. This approach minimizes the number of non-aligned
1669cc5169cSBart Van Assche * requests that are submitted to a block device if the start of a bio is not
1679cc5169cSBart Van Assche * aligned to a physical block boundary.
1689cc5169cSBart Van Assche */
get_max_io_size(struct bio * bio,const struct queue_limits * lim)1695a97806fSChristoph Hellwig static inline unsigned get_max_io_size(struct bio *bio,
170aa261f20SBart Van Assche const struct queue_limits *lim)
171d0e5fbb0SMing Lei {
172c55ddd90SChristoph Hellwig unsigned pbs = lim->physical_block_size >> SECTOR_SHIFT;
173c55ddd90SChristoph Hellwig unsigned lbs = lim->logical_block_size >> SECTOR_SHIFT;
174c55ddd90SChristoph Hellwig unsigned max_sectors = lim->max_sectors, start, end;
175d0e5fbb0SMing Lei
176c55ddd90SChristoph Hellwig if (lim->chunk_sectors) {
177efef739dSChristoph Hellwig max_sectors = min(max_sectors,
178efef739dSChristoph Hellwig blk_chunk_sectors_left(bio->bi_iter.bi_sector,
179c55ddd90SChristoph Hellwig lim->chunk_sectors));
180efef739dSChristoph Hellwig }
181d0e5fbb0SMing Lei
18284613bedSChristoph Hellwig start = bio->bi_iter.bi_sector & (pbs - 1);
18384613bedSChristoph Hellwig end = (start + max_sectors) & ~(pbs - 1);
18484613bedSChristoph Hellwig if (end > start)
18584613bedSChristoph Hellwig return end - start;
18684613bedSChristoph Hellwig return max_sectors & ~(lbs - 1);
187d0e5fbb0SMing Lei }
188d0e5fbb0SMing Lei
18995465318SBart Van Assche /**
19095465318SBart Van Assche * get_max_segment_size() - maximum number of bytes to add as a single segment
19195465318SBart Van Assche * @lim: Request queue limits.
19295465318SBart Van Assche * @start_page: See below.
19395465318SBart Van Assche * @offset: Offset from @start_page where to add a segment.
19495465318SBart Van Assche *
19595465318SBart Van Assche * Returns the maximum number of bytes that can be added as a single segment.
19695465318SBart Van Assche */
get_max_segment_size(const struct queue_limits * lim,struct page * start_page,unsigned long offset)197aa261f20SBart Van Assche static inline unsigned get_max_segment_size(const struct queue_limits *lim,
198c55ddd90SChristoph Hellwig struct page *start_page, unsigned long offset)
199dcebd755SMing Lei {
200c55ddd90SChristoph Hellwig unsigned long mask = lim->seg_boundary_mask;
201dcebd755SMing Lei
202429120f3SMing Lei offset = mask & (page_to_phys(start_page) + offset);
2034a2f704eSMing Lei
2044a2f704eSMing Lei /*
20595465318SBart Van Assche * Prevent an overflow if mask = ULONG_MAX and offset = 0 by adding 1
20695465318SBart Van Assche * after having calculated the minimum.
2074a2f704eSMing Lei */
20895465318SBart Van Assche return min(mask - offset, (unsigned long)lim->max_segment_size - 1) + 1;
209dcebd755SMing Lei }
210dcebd755SMing Lei
211708b25b3SBart Van Assche /**
212708b25b3SBart Van Assche * bvec_split_segs - verify whether or not a bvec should be split in the middle
213c55ddd90SChristoph Hellwig * @lim: [in] queue limits to split based on
214708b25b3SBart Van Assche * @bv: [in] bvec to examine
215708b25b3SBart Van Assche * @nsegs: [in,out] Number of segments in the bio being built. Incremented
216708b25b3SBart Van Assche * by the number of segments from @bv that may be appended to that
217708b25b3SBart Van Assche * bio without exceeding @max_segs
21867927d22SKeith Busch * @bytes: [in,out] Number of bytes in the bio being built. Incremented
21967927d22SKeith Busch * by the number of bytes from @bv that may be appended to that
22067927d22SKeith Busch * bio without exceeding @max_bytes
221708b25b3SBart Van Assche * @max_segs: [in] upper bound for *@nsegs
22267927d22SKeith Busch * @max_bytes: [in] upper bound for *@bytes
223708b25b3SBart Van Assche *
224708b25b3SBart Van Assche * When splitting a bio, it can happen that a bvec is encountered that is too
225708b25b3SBart Van Assche * big to fit in a single segment and hence that it has to be split in the
226708b25b3SBart Van Assche * middle. This function verifies whether or not that should happen. The value
227708b25b3SBart Van Assche * %true is returned if and only if appending the entire @bv to a bio with
228708b25b3SBart Van Assche * *@nsegs segments and *@sectors sectors would make that bio unacceptable for
229708b25b3SBart Van Assche * the block driver.
230dcebd755SMing Lei */
bvec_split_segs(const struct queue_limits * lim,const struct bio_vec * bv,unsigned * nsegs,unsigned * bytes,unsigned max_segs,unsigned max_bytes)231aa261f20SBart Van Assche static bool bvec_split_segs(const struct queue_limits *lim,
232aa261f20SBart Van Assche const struct bio_vec *bv, unsigned *nsegs, unsigned *bytes,
233aa261f20SBart Van Assche unsigned max_segs, unsigned max_bytes)
234dcebd755SMing Lei {
23567927d22SKeith Busch unsigned max_len = min(max_bytes, UINT_MAX) - *bytes;
236708b25b3SBart Van Assche unsigned len = min(bv->bv_len, max_len);
237dcebd755SMing Lei unsigned total_len = 0;
238ff9811b3SBart Van Assche unsigned seg_size = 0;
239dcebd755SMing Lei
240ff9811b3SBart Van Assche while (len && *nsegs < max_segs) {
241c55ddd90SChristoph Hellwig seg_size = get_max_segment_size(lim, bv->bv_page,
242429120f3SMing Lei bv->bv_offset + total_len);
243dcebd755SMing Lei seg_size = min(seg_size, len);
244dcebd755SMing Lei
245ff9811b3SBart Van Assche (*nsegs)++;
246dcebd755SMing Lei total_len += seg_size;
247dcebd755SMing Lei len -= seg_size;
248dcebd755SMing Lei
249c55ddd90SChristoph Hellwig if ((bv->bv_offset + total_len) & lim->virt_boundary_mask)
250dcebd755SMing Lei break;
251dcebd755SMing Lei }
252dcebd755SMing Lei
25367927d22SKeith Busch *bytes += total_len;
254dcebd755SMing Lei
255708b25b3SBart Van Assche /* tell the caller to split the bvec if it is too big to fit */
256708b25b3SBart Van Assche return len > 0 || bv->bv_len > max_len;
257dcebd755SMing Lei }
258dcebd755SMing Lei
259dad77584SBart Van Assche /**
2605a97806fSChristoph Hellwig * bio_split_rw - split a bio in two bios
261dad77584SBart Van Assche * @bio: [in] bio to be split
262c55ddd90SChristoph Hellwig * @lim: [in] queue limits to split based on
263dad77584SBart Van Assche * @segs: [out] number of segments in the bio with the first half of the sectors
2645a97806fSChristoph Hellwig * @bs: [in] bio set to allocate the clone from
265a85b3637SChristoph Hellwig * @max_bytes: [in] maximum number of bytes per bio
266dad77584SBart Van Assche *
267dad77584SBart Van Assche * Clone @bio, update the bi_iter of the clone to represent the first sectors
268dad77584SBart Van Assche * of @bio and update @bio->bi_iter to represent the remaining sectors. The
269dad77584SBart Van Assche * following is guaranteed for the cloned bio:
270a85b3637SChristoph Hellwig * - That it has at most @max_bytes worth of data
271dad77584SBart Van Assche * - That it has at most queue_max_segments(@q) segments.
272dad77584SBart Van Assche *
273dad77584SBart Van Assche * Except for discard requests the cloned bio will point at the bi_io_vec of
274dad77584SBart Van Assche * the original bio. It is the responsibility of the caller to ensure that the
275dad77584SBart Van Assche * original bio is not freed before the cloned bio. The caller is also
276dad77584SBart Van Assche * responsible for ensuring that @bs is only destroyed after processing of the
277dad77584SBart Van Assche * split bio has finished.
278dad77584SBart Van Assche */
bio_split_rw(struct bio * bio,const struct queue_limits * lim,unsigned * segs,struct bio_set * bs,unsigned max_bytes)279fd8f8edeSChristoph Hellwig struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim,
280a85b3637SChristoph Hellwig unsigned *segs, struct bio_set *bs, unsigned max_bytes)
28154efd50bSKent Overstreet {
2825014c311SJens Axboe struct bio_vec bv, bvprv, *bvprvp = NULL;
28354efd50bSKent Overstreet struct bvec_iter iter;
28467927d22SKeith Busch unsigned nsegs = 0, bytes = 0;
28554efd50bSKent Overstreet
286dcebd755SMing Lei bio_for_each_bvec(bv, bio, iter) {
28754efd50bSKent Overstreet /*
28854efd50bSKent Overstreet * If the queue doesn't support SG gaps and adding this
28954efd50bSKent Overstreet * offset would create a gap, disallow it.
29054efd50bSKent Overstreet */
291c55ddd90SChristoph Hellwig if (bvprvp && bvec_gap_to_prev(lim, bvprvp, bv.bv_offset))
29254efd50bSKent Overstreet goto split;
29354efd50bSKent Overstreet
294c55ddd90SChristoph Hellwig if (nsegs < lim->max_segments &&
29567927d22SKeith Busch bytes + bv.bv_len <= max_bytes &&
296708b25b3SBart Van Assche bv.bv_offset + bv.bv_len <= PAGE_SIZE) {
297708b25b3SBart Van Assche nsegs++;
29867927d22SKeith Busch bytes += bv.bv_len;
299c55ddd90SChristoph Hellwig } else {
300c55ddd90SChristoph Hellwig if (bvec_split_segs(lim, &bv, &nsegs, &bytes,
301c55ddd90SChristoph Hellwig lim->max_segments, max_bytes))
302e36f6204SKeith Busch goto split;
303e36f6204SKeith Busch }
304e36f6204SKeith Busch
30554efd50bSKent Overstreet bvprv = bv;
306578270bfSMing Lei bvprvp = &bvprv;
30754efd50bSKent Overstreet }
30854efd50bSKent Overstreet
309d627065dSChristoph Hellwig *segs = nsegs;
310d627065dSChristoph Hellwig return NULL;
31154efd50bSKent Overstreet split:
3129cea62b2SJens Axboe /*
3139cea62b2SJens Axboe * We can't sanely support splitting for a REQ_NOWAIT bio. End it
3149cea62b2SJens Axboe * with EAGAIN if splitting is required and return an error pointer.
3159cea62b2SJens Axboe */
3169cea62b2SJens Axboe if (bio->bi_opf & REQ_NOWAIT) {
3179cea62b2SJens Axboe bio->bi_status = BLK_STS_AGAIN;
3189cea62b2SJens Axboe bio_endio(bio);
3199cea62b2SJens Axboe return ERR_PTR(-EAGAIN);
3209cea62b2SJens Axboe }
3219cea62b2SJens Axboe
322bdced438SMing Lei *segs = nsegs;
323cc29e1bfSJeffle Xu
324cc29e1bfSJeffle Xu /*
32567927d22SKeith Busch * Individual bvecs might not be logical block aligned. Round down the
32667927d22SKeith Busch * split size so that each bio is properly block size aligned, even if
32767927d22SKeith Busch * we do not use the full hardware limits.
32867927d22SKeith Busch */
329c55ddd90SChristoph Hellwig bytes = ALIGN_DOWN(bytes, lim->logical_block_size);
33067927d22SKeith Busch
33167927d22SKeith Busch /*
332cc29e1bfSJeffle Xu * Bio splitting may cause subtle trouble such as hang when doing sync
333cc29e1bfSJeffle Xu * iopoll in direct IO routine. Given performance gain of iopoll for
334cc29e1bfSJeffle Xu * big IO can be trival, disable iopoll when split needed.
335cc29e1bfSJeffle Xu */
3366ce913feSChristoph Hellwig bio_clear_polled(bio);
33767927d22SKeith Busch return bio_split(bio, bytes >> SECTOR_SHIFT, GFP_NOIO, bs);
33854efd50bSKent Overstreet }
339fd8f8edeSChristoph Hellwig EXPORT_SYMBOL_GPL(bio_split_rw);
34054efd50bSKent Overstreet
341dad77584SBart Van Assche /**
3425a97806fSChristoph Hellwig * __bio_split_to_limits - split a bio to fit the queue limits
3435a97806fSChristoph Hellwig * @bio: bio to be split
344c55ddd90SChristoph Hellwig * @lim: queue limits to split based on
3455a97806fSChristoph Hellwig * @nr_segs: returns the number of segments in the returned bio
346dad77584SBart Van Assche *
3475a97806fSChristoph Hellwig * Check if @bio needs splitting based on the queue limits, and if so split off
3485a97806fSChristoph Hellwig * a bio fitting the limits from the beginning of @bio and return it. @bio is
3495a97806fSChristoph Hellwig * shortened to the remainder and re-submitted.
3505a97806fSChristoph Hellwig *
3515a97806fSChristoph Hellwig * The split bio is allocated from @q->bio_split, which is provided by the
3525a97806fSChristoph Hellwig * block layer.
353dad77584SBart Van Assche */
__bio_split_to_limits(struct bio * bio,const struct queue_limits * lim,unsigned int * nr_segs)354aa261f20SBart Van Assche struct bio *__bio_split_to_limits(struct bio *bio,
355aa261f20SBart Van Assche const struct queue_limits *lim,
356abd45c15SJens Axboe unsigned int *nr_segs)
35754efd50bSKent Overstreet {
35846754bd0SChristoph Hellwig struct bio_set *bs = &bio->bi_bdev->bd_disk->bio_split;
3595a97806fSChristoph Hellwig struct bio *split;
36054efd50bSKent Overstreet
3615a97806fSChristoph Hellwig switch (bio_op(bio)) {
3627afafc8aSAdrian Hunter case REQ_OP_DISCARD:
3637afafc8aSAdrian Hunter case REQ_OP_SECURE_ERASE:
364c55ddd90SChristoph Hellwig split = bio_split_discard(bio, lim, nr_segs, bs);
3657afafc8aSAdrian Hunter break;
366a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES:
367c55ddd90SChristoph Hellwig split = bio_split_write_zeroes(bio, lim, nr_segs, bs);
368a6f0788eSChaitanya Kulkarni break;
3697afafc8aSAdrian Hunter default:
370c55ddd90SChristoph Hellwig split = bio_split_rw(bio, lim, nr_segs, bs,
371c55ddd90SChristoph Hellwig get_max_io_size(bio, lim) << SECTOR_SHIFT);
372613b1488SJens Axboe if (IS_ERR(split))
373613b1488SJens Axboe return NULL;
3747afafc8aSAdrian Hunter break;
3757afafc8aSAdrian Hunter }
376bdced438SMing Lei
37754efd50bSKent Overstreet if (split) {
378613b1488SJens Axboe /* there isn't chance to merge the split bio */
3791eff9d32SJens Axboe split->bi_opf |= REQ_NOMERGE;
3806ac45aebSMing Lei
381957a2b34SMuchun Song blkcg_bio_issue_init(split);
3825a97806fSChristoph Hellwig bio_chain(split, bio);
3835a97806fSChristoph Hellwig trace_block_split(split, bio->bi_iter.bi_sector);
3845a97806fSChristoph Hellwig submit_bio_noacct(bio);
3855a97806fSChristoph Hellwig return split;
38654efd50bSKent Overstreet }
3875a97806fSChristoph Hellwig return bio;
38854efd50bSKent Overstreet }
38914ccb66bSChristoph Hellwig
390dad77584SBart Van Assche /**
3915a97806fSChristoph Hellwig * bio_split_to_limits - split a bio to fit the queue limits
3925a97806fSChristoph Hellwig * @bio: bio to be split
393dad77584SBart Van Assche *
3945a97806fSChristoph Hellwig * Check if @bio needs splitting based on the queue limits of @bio->bi_bdev, and
3955a97806fSChristoph Hellwig * if so split off a bio fitting the limits from the beginning of @bio and
3965a97806fSChristoph Hellwig * return it. @bio is shortened to the remainder and re-submitted.
3975a97806fSChristoph Hellwig *
3985a97806fSChristoph Hellwig * The split bio is allocated from @q->bio_split, which is provided by the
3995a97806fSChristoph Hellwig * block layer.
400dad77584SBart Van Assche */
bio_split_to_limits(struct bio * bio)4015a97806fSChristoph Hellwig struct bio *bio_split_to_limits(struct bio *bio)
40214ccb66bSChristoph Hellwig {
403aa261f20SBart Van Assche const struct queue_limits *lim = &bdev_get_queue(bio->bi_bdev)->limits;
40414ccb66bSChristoph Hellwig unsigned int nr_segs;
40514ccb66bSChristoph Hellwig
406c55ddd90SChristoph Hellwig if (bio_may_exceed_limits(bio, lim))
407c55ddd90SChristoph Hellwig return __bio_split_to_limits(bio, lim, &nr_segs);
4085a97806fSChristoph Hellwig return bio;
40914ccb66bSChristoph Hellwig }
4105a97806fSChristoph Hellwig EXPORT_SYMBOL(bio_split_to_limits);
41154efd50bSKent Overstreet
blk_recalc_rq_segments(struct request * rq)412e9cd19c0SChristoph Hellwig unsigned int blk_recalc_rq_segments(struct request *rq)
413d6d48196SJens Axboe {
4146869875fSChristoph Hellwig unsigned int nr_phys_segs = 0;
41567927d22SKeith Busch unsigned int bytes = 0;
416e9cd19c0SChristoph Hellwig struct req_iterator iter;
4176869875fSChristoph Hellwig struct bio_vec bv;
418d6d48196SJens Axboe
419e9cd19c0SChristoph Hellwig if (!rq->bio)
4201e428079SJens Axboe return 0;
421d6d48196SJens Axboe
422e9cd19c0SChristoph Hellwig switch (bio_op(rq->bio)) {
423a6f0788eSChaitanya Kulkarni case REQ_OP_DISCARD:
424a6f0788eSChaitanya Kulkarni case REQ_OP_SECURE_ERASE:
425a958937fSDavid Jeffery if (queue_max_discard_segments(rq->q) > 1) {
426a958937fSDavid Jeffery struct bio *bio = rq->bio;
427a958937fSDavid Jeffery
428a958937fSDavid Jeffery for_each_bio(bio)
429a958937fSDavid Jeffery nr_phys_segs++;
430a958937fSDavid Jeffery return nr_phys_segs;
431a958937fSDavid Jeffery }
432a958937fSDavid Jeffery return 1;
433a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES:
434f9d03f96SChristoph Hellwig return 0;
4352d9b02beSBart Van Assche default:
4362d9b02beSBart Van Assche break;
437a6f0788eSChaitanya Kulkarni }
4385cb8850cSKent Overstreet
439e9cd19c0SChristoph Hellwig rq_for_each_bvec(bv, rq, iter)
440c55ddd90SChristoph Hellwig bvec_split_segs(&rq->q->limits, &bv, &nr_phys_segs, &bytes,
441708b25b3SBart Van Assche UINT_MAX, UINT_MAX);
4421e428079SJens Axboe return nr_phys_segs;
4431e428079SJens Axboe }
4441e428079SJens Axboe
blk_next_sg(struct scatterlist ** sg,struct scatterlist * sglist)44548d7727cSMing Lei static inline struct scatterlist *blk_next_sg(struct scatterlist **sg,
446862e5a5eSMing Lei struct scatterlist *sglist)
447862e5a5eSMing Lei {
448862e5a5eSMing Lei if (!*sg)
449862e5a5eSMing Lei return sglist;
450862e5a5eSMing Lei
451862e5a5eSMing Lei /*
452862e5a5eSMing Lei * If the driver previously mapped a shorter list, we could see a
453862e5a5eSMing Lei * termination bit prematurely unless it fully inits the sg table
454862e5a5eSMing Lei * on each mapping. We KNOW that there must be more entries here
455862e5a5eSMing Lei * or the driver would be buggy, so force clear the termination bit
456862e5a5eSMing Lei * to avoid doing a full sg_init_table() in drivers for each command.
457862e5a5eSMing Lei */
458862e5a5eSMing Lei sg_unmark_end(*sg);
459862e5a5eSMing Lei return sg_next(*sg);
460862e5a5eSMing Lei }
461862e5a5eSMing Lei
blk_bvec_map_sg(struct request_queue * q,struct bio_vec * bvec,struct scatterlist * sglist,struct scatterlist ** sg)462862e5a5eSMing Lei static unsigned blk_bvec_map_sg(struct request_queue *q,
463862e5a5eSMing Lei struct bio_vec *bvec, struct scatterlist *sglist,
464862e5a5eSMing Lei struct scatterlist **sg)
465862e5a5eSMing Lei {
466862e5a5eSMing Lei unsigned nbytes = bvec->bv_len;
4678a96a0e4SChristoph Hellwig unsigned nsegs = 0, total = 0;
468862e5a5eSMing Lei
469862e5a5eSMing Lei while (nbytes > 0) {
4708a96a0e4SChristoph Hellwig unsigned offset = bvec->bv_offset + total;
471c55ddd90SChristoph Hellwig unsigned len = min(get_max_segment_size(&q->limits,
472c55ddd90SChristoph Hellwig bvec->bv_page, offset), nbytes);
473f9f76879SChristoph Hellwig struct page *page = bvec->bv_page;
474f9f76879SChristoph Hellwig
475f9f76879SChristoph Hellwig /*
476f9f76879SChristoph Hellwig * Unfortunately a fair number of drivers barf on scatterlists
477f9f76879SChristoph Hellwig * that have an offset larger than PAGE_SIZE, despite other
478f9f76879SChristoph Hellwig * subsystems dealing with that invariant just fine. For now
479f9f76879SChristoph Hellwig * stick to the legacy format where we never present those from
480f9f76879SChristoph Hellwig * the block layer, but the code below should be removed once
481f9f76879SChristoph Hellwig * these offenders (mostly MMC/SD drivers) are fixed.
482f9f76879SChristoph Hellwig */
483f9f76879SChristoph Hellwig page += (offset >> PAGE_SHIFT);
484f9f76879SChristoph Hellwig offset &= ~PAGE_MASK;
485862e5a5eSMing Lei
486862e5a5eSMing Lei *sg = blk_next_sg(sg, sglist);
487f9f76879SChristoph Hellwig sg_set_page(*sg, page, len, offset);
488862e5a5eSMing Lei
4898a96a0e4SChristoph Hellwig total += len;
4908a96a0e4SChristoph Hellwig nbytes -= len;
491862e5a5eSMing Lei nsegs++;
492862e5a5eSMing Lei }
493862e5a5eSMing Lei
494862e5a5eSMing Lei return nsegs;
495862e5a5eSMing Lei }
496862e5a5eSMing Lei
__blk_bvec_map_sg(struct bio_vec bv,struct scatterlist * sglist,struct scatterlist ** sg)49716e3e418SMing Lei static inline int __blk_bvec_map_sg(struct bio_vec bv,
49816e3e418SMing Lei struct scatterlist *sglist, struct scatterlist **sg)
49916e3e418SMing Lei {
50016e3e418SMing Lei *sg = blk_next_sg(sg, sglist);
50116e3e418SMing Lei sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset);
50216e3e418SMing Lei return 1;
50316e3e418SMing Lei }
50416e3e418SMing Lei
505f6970f83SMing Lei /* only try to merge bvecs into one sg if they are from two bios */
506f6970f83SMing Lei static inline bool
__blk_segment_map_sg_merge(struct request_queue * q,struct bio_vec * bvec,struct bio_vec * bvprv,struct scatterlist ** sg)507f6970f83SMing Lei __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec,
508f6970f83SMing Lei struct bio_vec *bvprv, struct scatterlist **sg)
509963ab9e5SAsias He {
510963ab9e5SAsias He
511963ab9e5SAsias He int nbytes = bvec->bv_len;
512963ab9e5SAsias He
513f6970f83SMing Lei if (!*sg)
514f6970f83SMing Lei return false;
515f6970f83SMing Lei
516b4b6cb61SMing Lei if ((*sg)->length + nbytes > queue_max_segment_size(q))
517f6970f83SMing Lei return false;
518f6970f83SMing Lei
5193dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, bvprv, bvec))
520f6970f83SMing Lei return false;
521963ab9e5SAsias He
522963ab9e5SAsias He (*sg)->length += nbytes;
523f6970f83SMing Lei
524f6970f83SMing Lei return true;
525963ab9e5SAsias He }
526963ab9e5SAsias He
__blk_bios_map_sg(struct request_queue * q,struct bio * bio,struct scatterlist * sglist,struct scatterlist ** sg)5275cb8850cSKent Overstreet static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio,
5285cb8850cSKent Overstreet struct scatterlist *sglist,
5295cb8850cSKent Overstreet struct scatterlist **sg)
5305cb8850cSKent Overstreet {
5313f649ab7SKees Cook struct bio_vec bvec, bvprv = { NULL };
5325cb8850cSKent Overstreet struct bvec_iter iter;
53338417468SChristoph Hellwig int nsegs = 0;
534f6970f83SMing Lei bool new_bio = false;
5355cb8850cSKent Overstreet
536f6970f83SMing Lei for_each_bio(bio) {
537f6970f83SMing Lei bio_for_each_bvec(bvec, bio, iter) {
538f6970f83SMing Lei /*
539f6970f83SMing Lei * Only try to merge bvecs from two bios given we
540f6970f83SMing Lei * have done bio internal merge when adding pages
541f6970f83SMing Lei * to bio
542f6970f83SMing Lei */
543f6970f83SMing Lei if (new_bio &&
544f6970f83SMing Lei __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg))
545f6970f83SMing Lei goto next_bvec;
546f6970f83SMing Lei
547f6970f83SMing Lei if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE)
548f6970f83SMing Lei nsegs += __blk_bvec_map_sg(bvec, sglist, sg);
549f6970f83SMing Lei else
550f6970f83SMing Lei nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg);
551f6970f83SMing Lei next_bvec:
552f6970f83SMing Lei new_bio = false;
553f6970f83SMing Lei }
554b21e11c5SMing Lei if (likely(bio->bi_iter.bi_size)) {
555f6970f83SMing Lei bvprv = bvec;
556f6970f83SMing Lei new_bio = true;
557f6970f83SMing Lei }
558b21e11c5SMing Lei }
5595cb8850cSKent Overstreet
5605cb8850cSKent Overstreet return nsegs;
5615cb8850cSKent Overstreet }
5625cb8850cSKent Overstreet
563d6d48196SJens Axboe /*
564d6d48196SJens Axboe * map a request to scatterlist, return number of sg entries setup. Caller
565d6d48196SJens Axboe * must make sure sg can hold rq->nr_phys_segments entries
566d6d48196SJens Axboe */
__blk_rq_map_sg(struct request_queue * q,struct request * rq,struct scatterlist * sglist,struct scatterlist ** last_sg)56789de1504SChristoph Hellwig int __blk_rq_map_sg(struct request_queue *q, struct request *rq,
56889de1504SChristoph Hellwig struct scatterlist *sglist, struct scatterlist **last_sg)
569d6d48196SJens Axboe {
5705cb8850cSKent Overstreet int nsegs = 0;
571d6d48196SJens Axboe
572f9d03f96SChristoph Hellwig if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
57389de1504SChristoph Hellwig nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, last_sg);
574f9d03f96SChristoph Hellwig else if (rq->bio)
57589de1504SChristoph Hellwig nsegs = __blk_bios_map_sg(q, rq->bio, sglist, last_sg);
576f18573abSFUJITA Tomonori
57789de1504SChristoph Hellwig if (*last_sg)
57889de1504SChristoph Hellwig sg_mark_end(*last_sg);
579d6d48196SJens Axboe
58012e57f59SMing Lei /*
58112e57f59SMing Lei * Something must have been wrong if the figured number of
58212e57f59SMing Lei * segment is bigger than number of req's physical segments
58312e57f59SMing Lei */
584f9d03f96SChristoph Hellwig WARN_ON(nsegs > blk_rq_nr_phys_segments(rq));
58512e57f59SMing Lei
586d6d48196SJens Axboe return nsegs;
587d6d48196SJens Axboe }
58889de1504SChristoph Hellwig EXPORT_SYMBOL(__blk_rq_map_sg);
589d6d48196SJens Axboe
blk_rq_get_max_sectors(struct request * rq,sector_t offset)590badf7f64SChristoph Hellwig static inline unsigned int blk_rq_get_max_sectors(struct request *rq,
591badf7f64SChristoph Hellwig sector_t offset)
592badf7f64SChristoph Hellwig {
593badf7f64SChristoph Hellwig struct request_queue *q = rq->q;
594c8875190SChristoph Hellwig unsigned int max_sectors;
595badf7f64SChristoph Hellwig
596badf7f64SChristoph Hellwig if (blk_rq_is_passthrough(rq))
597badf7f64SChristoph Hellwig return q->limits.max_hw_sectors;
598badf7f64SChristoph Hellwig
599c8875190SChristoph Hellwig max_sectors = blk_queue_get_max_sectors(q, req_op(rq));
600badf7f64SChristoph Hellwig if (!q->limits.chunk_sectors ||
601badf7f64SChristoph Hellwig req_op(rq) == REQ_OP_DISCARD ||
602badf7f64SChristoph Hellwig req_op(rq) == REQ_OP_SECURE_ERASE)
603c8875190SChristoph Hellwig return max_sectors;
604c8875190SChristoph Hellwig return min(max_sectors,
605c8875190SChristoph Hellwig blk_chunk_sectors_left(offset, q->limits.chunk_sectors));
606badf7f64SChristoph Hellwig }
607badf7f64SChristoph Hellwig
ll_new_hw_segment(struct request * req,struct bio * bio,unsigned int nr_phys_segs)60814ccb66bSChristoph Hellwig static inline int ll_new_hw_segment(struct request *req, struct bio *bio,
60914ccb66bSChristoph Hellwig unsigned int nr_phys_segs)
610d6d48196SJens Axboe {
6116b2b0459STejun Heo if (!blk_cgroup_mergeable(req, bio))
6126b2b0459STejun Heo goto no_merge;
6136b2b0459STejun Heo
6142705dfb2SMing Lei if (blk_integrity_merge_bio(req->q, req, bio) == false)
61513f05c8dSMartin K. Petersen goto no_merge;
61613f05c8dSMartin K. Petersen
6172705dfb2SMing Lei /* discard request merge won't add new segment */
6182705dfb2SMing Lei if (req_op(req) == REQ_OP_DISCARD)
6192705dfb2SMing Lei return 1;
6202705dfb2SMing Lei
6212705dfb2SMing Lei if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req))
62213f05c8dSMartin K. Petersen goto no_merge;
623d6d48196SJens Axboe
624d6d48196SJens Axboe /*
625d6d48196SJens Axboe * This will form the start of a new hw segment. Bump both
626d6d48196SJens Axboe * counters.
627d6d48196SJens Axboe */
628d6d48196SJens Axboe req->nr_phys_segments += nr_phys_segs;
629d6d48196SJens Axboe return 1;
63013f05c8dSMartin K. Petersen
63113f05c8dSMartin K. Petersen no_merge:
63214ccb66bSChristoph Hellwig req_set_nomerge(req->q, req);
63313f05c8dSMartin K. Petersen return 0;
634d6d48196SJens Axboe }
635d6d48196SJens Axboe
ll_back_merge_fn(struct request * req,struct bio * bio,unsigned int nr_segs)63614ccb66bSChristoph Hellwig int ll_back_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs)
637d6d48196SJens Axboe {
6385e7c4274SJens Axboe if (req_gap_back_merge(req, bio))
6395e7c4274SJens Axboe return 0;
6407f39add3SSagi Grimberg if (blk_integrity_rq(req) &&
6417f39add3SSagi Grimberg integrity_req_gap_back_merge(req, bio))
6427f39add3SSagi Grimberg return 0;
643a892c8d5SSatya Tangirala if (!bio_crypt_ctx_back_mergeable(req, bio))
644a892c8d5SSatya Tangirala return 0;
645f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) >
64617007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) {
64714ccb66bSChristoph Hellwig req_set_nomerge(req->q, req);
648d6d48196SJens Axboe return 0;
649d6d48196SJens Axboe }
650d6d48196SJens Axboe
65114ccb66bSChristoph Hellwig return ll_new_hw_segment(req, bio, nr_segs);
652d6d48196SJens Axboe }
653d6d48196SJens Axboe
ll_front_merge_fn(struct request * req,struct bio * bio,unsigned int nr_segs)654eda5cc99SChristoph Hellwig static int ll_front_merge_fn(struct request *req, struct bio *bio,
655eda5cc99SChristoph Hellwig unsigned int nr_segs)
656d6d48196SJens Axboe {
6575e7c4274SJens Axboe if (req_gap_front_merge(req, bio))
6585e7c4274SJens Axboe return 0;
6597f39add3SSagi Grimberg if (blk_integrity_rq(req) &&
6607f39add3SSagi Grimberg integrity_req_gap_front_merge(req, bio))
6617f39add3SSagi Grimberg return 0;
662a892c8d5SSatya Tangirala if (!bio_crypt_ctx_front_mergeable(req, bio))
663a892c8d5SSatya Tangirala return 0;
664f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) >
66517007f39SDamien Le Moal blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) {
66614ccb66bSChristoph Hellwig req_set_nomerge(req->q, req);
667d6d48196SJens Axboe return 0;
668d6d48196SJens Axboe }
669d6d48196SJens Axboe
67014ccb66bSChristoph Hellwig return ll_new_hw_segment(req, bio, nr_segs);
671d6d48196SJens Axboe }
672d6d48196SJens Axboe
req_attempt_discard_merge(struct request_queue * q,struct request * req,struct request * next)673445251d0SJens Axboe static bool req_attempt_discard_merge(struct request_queue *q, struct request *req,
674445251d0SJens Axboe struct request *next)
675445251d0SJens Axboe {
676445251d0SJens Axboe unsigned short segments = blk_rq_nr_discard_segments(req);
677445251d0SJens Axboe
678445251d0SJens Axboe if (segments >= queue_max_discard_segments(q))
679445251d0SJens Axboe goto no_merge;
680445251d0SJens Axboe if (blk_rq_sectors(req) + bio_sectors(next->bio) >
681445251d0SJens Axboe blk_rq_get_max_sectors(req, blk_rq_pos(req)))
682445251d0SJens Axboe goto no_merge;
683445251d0SJens Axboe
684445251d0SJens Axboe req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next);
685445251d0SJens Axboe return true;
686445251d0SJens Axboe no_merge:
687445251d0SJens Axboe req_set_nomerge(q, req);
688445251d0SJens Axboe return false;
689445251d0SJens Axboe }
690445251d0SJens Axboe
ll_merge_requests_fn(struct request_queue * q,struct request * req,struct request * next)691d6d48196SJens Axboe static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
692d6d48196SJens Axboe struct request *next)
693d6d48196SJens Axboe {
694d6d48196SJens Axboe int total_phys_segments;
695d6d48196SJens Axboe
6965e7c4274SJens Axboe if (req_gap_back_merge(req, next->bio))
697854fbb9cSKeith Busch return 0;
698854fbb9cSKeith Busch
699d6d48196SJens Axboe /*
700d6d48196SJens Axboe * Will it become too large?
701d6d48196SJens Axboe */
702f31dc1cdSMartin K. Petersen if ((blk_rq_sectors(req) + blk_rq_sectors(next)) >
70317007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req)))
704d6d48196SJens Axboe return 0;
705d6d48196SJens Axboe
706d6d48196SJens Axboe total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
707943b40c8SMing Lei if (total_phys_segments > blk_rq_get_max_segments(req))
708d6d48196SJens Axboe return 0;
709d6d48196SJens Axboe
7106b2b0459STejun Heo if (!blk_cgroup_mergeable(req, next->bio))
7116b2b0459STejun Heo return 0;
7126b2b0459STejun Heo
7134eaf99beSMartin K. Petersen if (blk_integrity_merge_rq(q, req, next) == false)
71413f05c8dSMartin K. Petersen return 0;
71513f05c8dSMartin K. Petersen
716a892c8d5SSatya Tangirala if (!bio_crypt_ctx_merge_rq(req, next))
717a892c8d5SSatya Tangirala return 0;
718a892c8d5SSatya Tangirala
719d6d48196SJens Axboe /* Merge is OK... */
720d6d48196SJens Axboe req->nr_phys_segments = total_phys_segments;
721d6d48196SJens Axboe return 1;
722d6d48196SJens Axboe }
723d6d48196SJens Axboe
72480a761fdSTejun Heo /**
72580a761fdSTejun Heo * blk_rq_set_mixed_merge - mark a request as mixed merge
72680a761fdSTejun Heo * @rq: request to mark as mixed merge
72780a761fdSTejun Heo *
72880a761fdSTejun Heo * Description:
72980a761fdSTejun Heo * @rq is about to be mixed merged. Make sure the attributes
73080a761fdSTejun Heo * which can be mixed are set in each bio and mark @rq as mixed
73180a761fdSTejun Heo * merged.
73280a761fdSTejun Heo */
blk_rq_set_mixed_merge(struct request * rq)73380a761fdSTejun Heo void blk_rq_set_mixed_merge(struct request *rq)
73480a761fdSTejun Heo {
73516458cf3SBart Van Assche blk_opf_t ff = rq->cmd_flags & REQ_FAILFAST_MASK;
73680a761fdSTejun Heo struct bio *bio;
73780a761fdSTejun Heo
738e8064021SChristoph Hellwig if (rq->rq_flags & RQF_MIXED_MERGE)
73980a761fdSTejun Heo return;
74080a761fdSTejun Heo
74180a761fdSTejun Heo /*
74280a761fdSTejun Heo * @rq will no longer represent mixable attributes for all the
74380a761fdSTejun Heo * contained bios. It will just track those of the first one.
74480a761fdSTejun Heo * Distributes the attributs to each bio.
74580a761fdSTejun Heo */
74680a761fdSTejun Heo for (bio = rq->bio; bio; bio = bio->bi_next) {
7471eff9d32SJens Axboe WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) &&
7481eff9d32SJens Axboe (bio->bi_opf & REQ_FAILFAST_MASK) != ff);
7491eff9d32SJens Axboe bio->bi_opf |= ff;
75080a761fdSTejun Heo }
751e8064021SChristoph Hellwig rq->rq_flags |= RQF_MIXED_MERGE;
75280a761fdSTejun Heo }
75380a761fdSTejun Heo
bio_failfast(const struct bio * bio)754f3ca7386SJens Axboe static inline blk_opf_t bio_failfast(const struct bio *bio)
7553ce6a115SMing Lei {
7563ce6a115SMing Lei if (bio->bi_opf & REQ_RAHEAD)
7573ce6a115SMing Lei return REQ_FAILFAST_MASK;
7583ce6a115SMing Lei
7593ce6a115SMing Lei return bio->bi_opf & REQ_FAILFAST_MASK;
7603ce6a115SMing Lei }
7613ce6a115SMing Lei
7623ce6a115SMing Lei /*
7633ce6a115SMing Lei * After we are marked as MIXED_MERGE, any new RA bio has to be updated
7643ce6a115SMing Lei * as failfast, and request's failfast has to be updated in case of
7653ce6a115SMing Lei * front merge.
7663ce6a115SMing Lei */
blk_update_mixed_merge(struct request * req,struct bio * bio,bool front_merge)7673ce6a115SMing Lei static inline void blk_update_mixed_merge(struct request *req,
7683ce6a115SMing Lei struct bio *bio, bool front_merge)
7693ce6a115SMing Lei {
7703ce6a115SMing Lei if (req->rq_flags & RQF_MIXED_MERGE) {
7713ce6a115SMing Lei if (bio->bi_opf & REQ_RAHEAD)
7723ce6a115SMing Lei bio->bi_opf |= REQ_FAILFAST_MASK;
7733ce6a115SMing Lei
7743ce6a115SMing Lei if (front_merge) {
7753ce6a115SMing Lei req->cmd_flags &= ~REQ_FAILFAST_MASK;
7763ce6a115SMing Lei req->cmd_flags |= bio->bi_opf & REQ_FAILFAST_MASK;
7773ce6a115SMing Lei }
7783ce6a115SMing Lei }
7793ce6a115SMing Lei }
7803ce6a115SMing Lei
blk_account_io_merge_request(struct request * req)781b9c54f56SKonstantin Khlebnikov static void blk_account_io_merge_request(struct request *req)
78226308eabSJerome Marchand {
78326308eabSJerome Marchand if (blk_do_io_stat(req)) {
784112f158fSMike Snitzer part_stat_lock();
785b9c54f56SKonstantin Khlebnikov part_stat_inc(req->part, merges[op_stat_group(req_op(req))]);
786e5d98cc3SYu Kuai part_stat_local_dec(req->part,
787e5d98cc3SYu Kuai in_flight[op_is_write(req_op(req))]);
78826308eabSJerome Marchand part_stat_unlock();
78926308eabSJerome Marchand }
79026308eabSJerome Marchand }
791b9c54f56SKonstantin Khlebnikov
blk_try_req_merge(struct request * req,struct request * next)792e96c0d83SEric Biggers static enum elv_merge blk_try_req_merge(struct request *req,
793e96c0d83SEric Biggers struct request *next)
79469840466SJianchao Wang {
79569840466SJianchao Wang if (blk_discard_mergable(req))
79669840466SJianchao Wang return ELEVATOR_DISCARD_MERGE;
79769840466SJianchao Wang else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next))
79869840466SJianchao Wang return ELEVATOR_BACK_MERGE;
79969840466SJianchao Wang
80069840466SJianchao Wang return ELEVATOR_NO_MERGE;
80169840466SJianchao Wang }
80226308eabSJerome Marchand
803d6d48196SJens Axboe /*
804b973cb7eSJens Axboe * For non-mq, this has to be called with the request spinlock acquired.
805b973cb7eSJens Axboe * For mq with scheduling, the appropriate queue wide lock should be held.
806d6d48196SJens Axboe */
attempt_merge(struct request_queue * q,struct request * req,struct request * next)807b973cb7eSJens Axboe static struct request *attempt_merge(struct request_queue *q,
808b973cb7eSJens Axboe struct request *req, struct request *next)
809d6d48196SJens Axboe {
810d6d48196SJens Axboe if (!rq_mergeable(req) || !rq_mergeable(next))
811b973cb7eSJens Axboe return NULL;
812d6d48196SJens Axboe
813288dab8aSChristoph Hellwig if (req_op(req) != req_op(next))
814b973cb7eSJens Axboe return NULL;
815f31dc1cdSMartin K. Petersen
81679bb1dbdSChristoph Hellwig if (rq_data_dir(req) != rq_data_dir(next))
817b973cb7eSJens Axboe return NULL;
818d6d48196SJens Axboe
819668ffc03SDamien Le Moal if (req->ioprio != next->ioprio)
820668ffc03SDamien Le Moal return NULL;
821668ffc03SDamien Le Moal
822cb6934f8SJens Axboe /*
823d6d48196SJens Axboe * If we are allowed to merge, then append bio list
824d6d48196SJens Axboe * from next to rq and release next. merge_requests_fn
825d6d48196SJens Axboe * will have updated segment counts, update sector
826445251d0SJens Axboe * counts here. Handle DISCARDs separately, as they
827445251d0SJens Axboe * have separate settings.
828d6d48196SJens Axboe */
82969840466SJianchao Wang
83069840466SJianchao Wang switch (blk_try_req_merge(req, next)) {
83169840466SJianchao Wang case ELEVATOR_DISCARD_MERGE:
832445251d0SJens Axboe if (!req_attempt_discard_merge(q, req, next))
833445251d0SJens Axboe return NULL;
83469840466SJianchao Wang break;
83569840466SJianchao Wang case ELEVATOR_BACK_MERGE:
83669840466SJianchao Wang if (!ll_merge_requests_fn(q, req, next))
837b973cb7eSJens Axboe return NULL;
83869840466SJianchao Wang break;
83969840466SJianchao Wang default:
84069840466SJianchao Wang return NULL;
84169840466SJianchao Wang }
842d6d48196SJens Axboe
843d6d48196SJens Axboe /*
84480a761fdSTejun Heo * If failfast settings disagree or any of the two is already
84580a761fdSTejun Heo * a mixed merge, mark both as mixed before proceeding. This
84680a761fdSTejun Heo * makes sure that all involved bios have mixable attributes
84780a761fdSTejun Heo * set properly.
84880a761fdSTejun Heo */
849e8064021SChristoph Hellwig if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) ||
85080a761fdSTejun Heo (req->cmd_flags & REQ_FAILFAST_MASK) !=
85180a761fdSTejun Heo (next->cmd_flags & REQ_FAILFAST_MASK)) {
85280a761fdSTejun Heo blk_rq_set_mixed_merge(req);
85380a761fdSTejun Heo blk_rq_set_mixed_merge(next);
85480a761fdSTejun Heo }
85580a761fdSTejun Heo
85680a761fdSTejun Heo /*
857522a7775SOmar Sandoval * At this point we have either done a back merge or front merge. We
858522a7775SOmar Sandoval * need the smaller start_time_ns of the merged requests to be the
859522a7775SOmar Sandoval * current request for accounting purposes.
860d6d48196SJens Axboe */
861522a7775SOmar Sandoval if (next->start_time_ns < req->start_time_ns)
862522a7775SOmar Sandoval req->start_time_ns = next->start_time_ns;
863d6d48196SJens Axboe
864d6d48196SJens Axboe req->biotail->bi_next = next->bio;
865d6d48196SJens Axboe req->biotail = next->biotail;
866d6d48196SJens Axboe
867a2dec7b3STejun Heo req->__data_len += blk_rq_bytes(next);
868d6d48196SJens Axboe
8692a5cf35cSMing Lei if (!blk_discard_mergable(req))
870d6d48196SJens Axboe elv_merge_requests(q, req, next);
871d6d48196SJens Axboe
8729cd1e566SEric Biggers blk_crypto_rq_put_keyslot(next);
8739cd1e566SEric Biggers
87442dad764SJerome Marchand /*
87542dad764SJerome Marchand * 'next' is going away, so update stats accordingly
87642dad764SJerome Marchand */
877b9c54f56SKonstantin Khlebnikov blk_account_io_merge_request(next);
878d6d48196SJens Axboe
879a54895faSChristoph Hellwig trace_block_rq_merge(next);
880f3bdc62fSJan Kara
881e4d750c9SJens Axboe /*
882e4d750c9SJens Axboe * ownership of bio passed from next to req, return 'next' for
883e4d750c9SJens Axboe * the caller to free
884e4d750c9SJens Axboe */
8851cd96c24SBoaz Harrosh next->bio = NULL;
886b973cb7eSJens Axboe return next;
887d6d48196SJens Axboe }
888d6d48196SJens Axboe
attempt_back_merge(struct request_queue * q,struct request * rq)889eda5cc99SChristoph Hellwig static struct request *attempt_back_merge(struct request_queue *q,
890eda5cc99SChristoph Hellwig struct request *rq)
891d6d48196SJens Axboe {
892d6d48196SJens Axboe struct request *next = elv_latter_request(q, rq);
893d6d48196SJens Axboe
894d6d48196SJens Axboe if (next)
895d6d48196SJens Axboe return attempt_merge(q, rq, next);
896d6d48196SJens Axboe
897b973cb7eSJens Axboe return NULL;
898d6d48196SJens Axboe }
899d6d48196SJens Axboe
attempt_front_merge(struct request_queue * q,struct request * rq)900eda5cc99SChristoph Hellwig static struct request *attempt_front_merge(struct request_queue *q,
901eda5cc99SChristoph Hellwig struct request *rq)
902d6d48196SJens Axboe {
903d6d48196SJens Axboe struct request *prev = elv_former_request(q, rq);
904d6d48196SJens Axboe
905d6d48196SJens Axboe if (prev)
906d6d48196SJens Axboe return attempt_merge(q, prev, rq);
907d6d48196SJens Axboe
908b973cb7eSJens Axboe return NULL;
909d6d48196SJens Axboe }
9105e84ea3aSJens Axboe
911fd2ef39cSJan Kara /*
912fd2ef39cSJan Kara * Try to merge 'next' into 'rq'. Return true if the merge happened, false
913fd2ef39cSJan Kara * otherwise. The caller is responsible for freeing 'next' if the merge
914fd2ef39cSJan Kara * happened.
915fd2ef39cSJan Kara */
blk_attempt_req_merge(struct request_queue * q,struct request * rq,struct request * next)916fd2ef39cSJan Kara bool blk_attempt_req_merge(struct request_queue *q, struct request *rq,
9175e84ea3aSJens Axboe struct request *next)
9185e84ea3aSJens Axboe {
919fd2ef39cSJan Kara return attempt_merge(q, rq, next);
9205e84ea3aSJens Axboe }
921050c8ea8STejun Heo
blk_rq_merge_ok(struct request * rq,struct bio * bio)922050c8ea8STejun Heo bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
923050c8ea8STejun Heo {
924e2a60da7SMartin K. Petersen if (!rq_mergeable(rq) || !bio_mergeable(bio))
925050c8ea8STejun Heo return false;
926050c8ea8STejun Heo
927288dab8aSChristoph Hellwig if (req_op(rq) != bio_op(bio))
928f31dc1cdSMartin K. Petersen return false;
929f31dc1cdSMartin K. Petersen
930050c8ea8STejun Heo /* different data direction or already started, don't merge */
931050c8ea8STejun Heo if (bio_data_dir(bio) != rq_data_dir(rq))
932050c8ea8STejun Heo return false;
933050c8ea8STejun Heo
9346b2b0459STejun Heo /* don't merge across cgroup boundaries */
9356b2b0459STejun Heo if (!blk_cgroup_mergeable(rq, bio))
9366b2b0459STejun Heo return false;
9376b2b0459STejun Heo
938050c8ea8STejun Heo /* only merge integrity protected bio into ditto rq */
9394eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(rq->q, rq, bio) == false)
940050c8ea8STejun Heo return false;
941050c8ea8STejun Heo
942a892c8d5SSatya Tangirala /* Only merge if the crypt contexts are compatible */
943a892c8d5SSatya Tangirala if (!bio_crypt_rq_ctx_compatible(rq, bio))
944a892c8d5SSatya Tangirala return false;
945a892c8d5SSatya Tangirala
946668ffc03SDamien Le Moal if (rq->ioprio != bio_prio(bio))
947668ffc03SDamien Le Moal return false;
948668ffc03SDamien Le Moal
949050c8ea8STejun Heo return true;
950050c8ea8STejun Heo }
951050c8ea8STejun Heo
blk_try_merge(struct request * rq,struct bio * bio)95234fe7c05SChristoph Hellwig enum elv_merge blk_try_merge(struct request *rq, struct bio *bio)
953050c8ea8STejun Heo {
95469840466SJianchao Wang if (blk_discard_mergable(rq))
9551e739730SChristoph Hellwig return ELEVATOR_DISCARD_MERGE;
9561e739730SChristoph Hellwig else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
957050c8ea8STejun Heo return ELEVATOR_BACK_MERGE;
9584f024f37SKent Overstreet else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector)
959050c8ea8STejun Heo return ELEVATOR_FRONT_MERGE;
960050c8ea8STejun Heo return ELEVATOR_NO_MERGE;
961050c8ea8STejun Heo }
9628e756373SBaolin Wang
blk_account_io_merge_bio(struct request * req)9638e756373SBaolin Wang static void blk_account_io_merge_bio(struct request *req)
9648e756373SBaolin Wang {
9658e756373SBaolin Wang if (!blk_do_io_stat(req))
9668e756373SBaolin Wang return;
9678e756373SBaolin Wang
9688e756373SBaolin Wang part_stat_lock();
9698e756373SBaolin Wang part_stat_inc(req->part, merges[op_stat_group(req_op(req))]);
9708e756373SBaolin Wang part_stat_unlock();
9718e756373SBaolin Wang }
9728e756373SBaolin Wang
973eda5cc99SChristoph Hellwig enum bio_merge_status {
974eda5cc99SChristoph Hellwig BIO_MERGE_OK,
975eda5cc99SChristoph Hellwig BIO_MERGE_NONE,
976eda5cc99SChristoph Hellwig BIO_MERGE_FAILED,
977eda5cc99SChristoph Hellwig };
978eda5cc99SChristoph Hellwig
bio_attempt_back_merge(struct request * req,struct bio * bio,unsigned int nr_segs)979eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_back_merge(struct request *req,
980eda5cc99SChristoph Hellwig struct bio *bio, unsigned int nr_segs)
9818e756373SBaolin Wang {
9823ce6a115SMing Lei const blk_opf_t ff = bio_failfast(bio);
9838e756373SBaolin Wang
9848e756373SBaolin Wang if (!ll_back_merge_fn(req, bio, nr_segs))
9857d7ca7c5SBaolin Wang return BIO_MERGE_FAILED;
9868e756373SBaolin Wang
987e8a676d6SChristoph Hellwig trace_block_bio_backmerge(bio);
9888e756373SBaolin Wang rq_qos_merge(req->q, req, bio);
9898e756373SBaolin Wang
9908e756373SBaolin Wang if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
9918e756373SBaolin Wang blk_rq_set_mixed_merge(req);
9928e756373SBaolin Wang
9933ce6a115SMing Lei blk_update_mixed_merge(req, bio, false);
9943ce6a115SMing Lei
9958e756373SBaolin Wang req->biotail->bi_next = bio;
9968e756373SBaolin Wang req->biotail = bio;
9978e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size;
9988e756373SBaolin Wang
9998e756373SBaolin Wang bio_crypt_free_ctx(bio);
10008e756373SBaolin Wang
10018e756373SBaolin Wang blk_account_io_merge_bio(req);
10027d7ca7c5SBaolin Wang return BIO_MERGE_OK;
10038e756373SBaolin Wang }
10048e756373SBaolin Wang
bio_attempt_front_merge(struct request * req,struct bio * bio,unsigned int nr_segs)1005eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_front_merge(struct request *req,
1006eda5cc99SChristoph Hellwig struct bio *bio, unsigned int nr_segs)
10078e756373SBaolin Wang {
10083ce6a115SMing Lei const blk_opf_t ff = bio_failfast(bio);
10098e756373SBaolin Wang
10108e756373SBaolin Wang if (!ll_front_merge_fn(req, bio, nr_segs))
10117d7ca7c5SBaolin Wang return BIO_MERGE_FAILED;
10128e756373SBaolin Wang
1013e8a676d6SChristoph Hellwig trace_block_bio_frontmerge(bio);
10148e756373SBaolin Wang rq_qos_merge(req->q, req, bio);
10158e756373SBaolin Wang
10168e756373SBaolin Wang if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
10178e756373SBaolin Wang blk_rq_set_mixed_merge(req);
10188e756373SBaolin Wang
10193ce6a115SMing Lei blk_update_mixed_merge(req, bio, true);
10203ce6a115SMing Lei
10218e756373SBaolin Wang bio->bi_next = req->bio;
10228e756373SBaolin Wang req->bio = bio;
10238e756373SBaolin Wang
10248e756373SBaolin Wang req->__sector = bio->bi_iter.bi_sector;
10258e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size;
10268e756373SBaolin Wang
10278e756373SBaolin Wang bio_crypt_do_front_merge(req, bio);
10288e756373SBaolin Wang
10298e756373SBaolin Wang blk_account_io_merge_bio(req);
10307d7ca7c5SBaolin Wang return BIO_MERGE_OK;
10318e756373SBaolin Wang }
10328e756373SBaolin Wang
bio_attempt_discard_merge(struct request_queue * q,struct request * req,struct bio * bio)1033eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q,
1034eda5cc99SChristoph Hellwig struct request *req, struct bio *bio)
10358e756373SBaolin Wang {
10368e756373SBaolin Wang unsigned short segments = blk_rq_nr_discard_segments(req);
10378e756373SBaolin Wang
10388e756373SBaolin Wang if (segments >= queue_max_discard_segments(q))
10398e756373SBaolin Wang goto no_merge;
10408e756373SBaolin Wang if (blk_rq_sectors(req) + bio_sectors(bio) >
10418e756373SBaolin Wang blk_rq_get_max_sectors(req, blk_rq_pos(req)))
10428e756373SBaolin Wang goto no_merge;
10438e756373SBaolin Wang
10448e756373SBaolin Wang rq_qos_merge(q, req, bio);
10458e756373SBaolin Wang
10468e756373SBaolin Wang req->biotail->bi_next = bio;
10478e756373SBaolin Wang req->biotail = bio;
10488e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size;
10498e756373SBaolin Wang req->nr_phys_segments = segments + 1;
10508e756373SBaolin Wang
10518e756373SBaolin Wang blk_account_io_merge_bio(req);
10527d7ca7c5SBaolin Wang return BIO_MERGE_OK;
10538e756373SBaolin Wang no_merge:
10548e756373SBaolin Wang req_set_nomerge(q, req);
10557d7ca7c5SBaolin Wang return BIO_MERGE_FAILED;
10567d7ca7c5SBaolin Wang }
10577d7ca7c5SBaolin Wang
blk_attempt_bio_merge(struct request_queue * q,struct request * rq,struct bio * bio,unsigned int nr_segs,bool sched_allow_merge)10587d7ca7c5SBaolin Wang static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q,
10597d7ca7c5SBaolin Wang struct request *rq,
10607d7ca7c5SBaolin Wang struct bio *bio,
10617d7ca7c5SBaolin Wang unsigned int nr_segs,
10627d7ca7c5SBaolin Wang bool sched_allow_merge)
10637d7ca7c5SBaolin Wang {
10647d7ca7c5SBaolin Wang if (!blk_rq_merge_ok(rq, bio))
10657d7ca7c5SBaolin Wang return BIO_MERGE_NONE;
10667d7ca7c5SBaolin Wang
10677d7ca7c5SBaolin Wang switch (blk_try_merge(rq, bio)) {
10687d7ca7c5SBaolin Wang case ELEVATOR_BACK_MERGE:
1069265600b7SBaolin Wang if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio))
10707d7ca7c5SBaolin Wang return bio_attempt_back_merge(rq, bio, nr_segs);
10717d7ca7c5SBaolin Wang break;
10727d7ca7c5SBaolin Wang case ELEVATOR_FRONT_MERGE:
1073265600b7SBaolin Wang if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio))
10747d7ca7c5SBaolin Wang return bio_attempt_front_merge(rq, bio, nr_segs);
10757d7ca7c5SBaolin Wang break;
10767d7ca7c5SBaolin Wang case ELEVATOR_DISCARD_MERGE:
10777d7ca7c5SBaolin Wang return bio_attempt_discard_merge(q, rq, bio);
10787d7ca7c5SBaolin Wang default:
10797d7ca7c5SBaolin Wang return BIO_MERGE_NONE;
10807d7ca7c5SBaolin Wang }
10817d7ca7c5SBaolin Wang
10827d7ca7c5SBaolin Wang return BIO_MERGE_FAILED;
10838e756373SBaolin Wang }
10848e756373SBaolin Wang
10858e756373SBaolin Wang /**
10868e756373SBaolin Wang * blk_attempt_plug_merge - try to merge with %current's plugged list
10878e756373SBaolin Wang * @q: request_queue new bio is being queued at
10888e756373SBaolin Wang * @bio: new bio being queued
10898e756373SBaolin Wang * @nr_segs: number of segments in @bio
109087c037d1SJens Axboe * from the passed in @q already in the plug list
10918e756373SBaolin Wang *
1092d38a9c04SJens Axboe * Determine whether @bio being queued on @q can be merged with the previous
1093d38a9c04SJens Axboe * request on %current's plugged list. Returns %true if merge was successful,
10948e756373SBaolin Wang * otherwise %false.
10958e756373SBaolin Wang *
10968e756373SBaolin Wang * Plugging coalesces IOs from the same issuer for the same purpose without
10978e756373SBaolin Wang * going through @q->queue_lock. As such it's more of an issuing mechanism
10988e756373SBaolin Wang * than scheduling, and the request, while may have elvpriv data, is not
10998e756373SBaolin Wang * added on the elevator at this point. In addition, we don't have
11008e756373SBaolin Wang * reliable access to the elevator outside queue lock. Only check basic
11018e756373SBaolin Wang * merging parameters without querying the elevator.
11028e756373SBaolin Wang *
11038e756373SBaolin Wang * Caller must ensure !blk_queue_nomerges(q) beforehand.
11048e756373SBaolin Wang */
blk_attempt_plug_merge(struct request_queue * q,struct bio * bio,unsigned int nr_segs)11058e756373SBaolin Wang bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
11060c5bcc92SChristoph Hellwig unsigned int nr_segs)
11078e756373SBaolin Wang {
11088e756373SBaolin Wang struct blk_plug *plug;
11098e756373SBaolin Wang struct request *rq;
11108e756373SBaolin Wang
11116deacb3bSChristoph Hellwig plug = blk_mq_plug(bio);
1112bc490f81SJens Axboe if (!plug || rq_list_empty(plug->mq_list))
11138e756373SBaolin Wang return false;
11148e756373SBaolin Wang
11155b205071SJens Axboe rq_list_for_each(&plug->mq_list, rq) {
111687c037d1SJens Axboe if (rq->q == q) {
1117a1cb6537SMing Lei if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) ==
1118a1cb6537SMing Lei BIO_MERGE_OK)
11198e756373SBaolin Wang return true;
11205b205071SJens Axboe break;
11215b205071SJens Axboe }
11225b205071SJens Axboe
11235b205071SJens Axboe /*
11245b205071SJens Axboe * Only keep iterating plug list for merges if we have multiple
11255b205071SJens Axboe * queues
11265b205071SJens Axboe */
11275b205071SJens Axboe if (!plug->multiple_queues)
11285b205071SJens Axboe break;
1129a1cb6537SMing Lei }
11308e756373SBaolin Wang return false;
11318e756373SBaolin Wang }
1132bdc6a287SBaolin Wang
1133bdc6a287SBaolin Wang /*
1134bdc6a287SBaolin Wang * Iterate list of requests and see if we can merge this bio with any
1135bdc6a287SBaolin Wang * of them.
1136bdc6a287SBaolin Wang */
blk_bio_list_merge(struct request_queue * q,struct list_head * list,struct bio * bio,unsigned int nr_segs)1137bdc6a287SBaolin Wang bool blk_bio_list_merge(struct request_queue *q, struct list_head *list,
1138bdc6a287SBaolin Wang struct bio *bio, unsigned int nr_segs)
1139bdc6a287SBaolin Wang {
1140bdc6a287SBaolin Wang struct request *rq;
1141bdc6a287SBaolin Wang int checked = 8;
1142bdc6a287SBaolin Wang
1143bdc6a287SBaolin Wang list_for_each_entry_reverse(rq, list, queuelist) {
1144bdc6a287SBaolin Wang if (!checked--)
1145bdc6a287SBaolin Wang break;
1146bdc6a287SBaolin Wang
11477d7ca7c5SBaolin Wang switch (blk_attempt_bio_merge(q, rq, bio, nr_segs, true)) {
11487d7ca7c5SBaolin Wang case BIO_MERGE_NONE:
1149bdc6a287SBaolin Wang continue;
11507d7ca7c5SBaolin Wang case BIO_MERGE_OK:
11517d7ca7c5SBaolin Wang return true;
11527d7ca7c5SBaolin Wang case BIO_MERGE_FAILED:
11537d7ca7c5SBaolin Wang return false;
1154bdc6a287SBaolin Wang }
1155bdc6a287SBaolin Wang
1156bdc6a287SBaolin Wang }
1157bdc6a287SBaolin Wang
1158bdc6a287SBaolin Wang return false;
1159bdc6a287SBaolin Wang }
1160bdc6a287SBaolin Wang EXPORT_SYMBOL_GPL(blk_bio_list_merge);
1161eda5cc99SChristoph Hellwig
blk_mq_sched_try_merge(struct request_queue * q,struct bio * bio,unsigned int nr_segs,struct request ** merged_request)1162eda5cc99SChristoph Hellwig bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
1163eda5cc99SChristoph Hellwig unsigned int nr_segs, struct request **merged_request)
1164eda5cc99SChristoph Hellwig {
1165eda5cc99SChristoph Hellwig struct request *rq;
1166eda5cc99SChristoph Hellwig
1167eda5cc99SChristoph Hellwig switch (elv_merge(q, &rq, bio)) {
1168eda5cc99SChristoph Hellwig case ELEVATOR_BACK_MERGE:
1169eda5cc99SChristoph Hellwig if (!blk_mq_sched_allow_merge(q, rq, bio))
1170eda5cc99SChristoph Hellwig return false;
1171eda5cc99SChristoph Hellwig if (bio_attempt_back_merge(rq, bio, nr_segs) != BIO_MERGE_OK)
1172eda5cc99SChristoph Hellwig return false;
1173eda5cc99SChristoph Hellwig *merged_request = attempt_back_merge(q, rq);
1174eda5cc99SChristoph Hellwig if (!*merged_request)
1175eda5cc99SChristoph Hellwig elv_merged_request(q, rq, ELEVATOR_BACK_MERGE);
1176eda5cc99SChristoph Hellwig return true;
1177eda5cc99SChristoph Hellwig case ELEVATOR_FRONT_MERGE:
1178eda5cc99SChristoph Hellwig if (!blk_mq_sched_allow_merge(q, rq, bio))
1179eda5cc99SChristoph Hellwig return false;
1180eda5cc99SChristoph Hellwig if (bio_attempt_front_merge(rq, bio, nr_segs) != BIO_MERGE_OK)
1181eda5cc99SChristoph Hellwig return false;
1182eda5cc99SChristoph Hellwig *merged_request = attempt_front_merge(q, rq);
1183eda5cc99SChristoph Hellwig if (!*merged_request)
1184eda5cc99SChristoph Hellwig elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE);
1185eda5cc99SChristoph Hellwig return true;
1186eda5cc99SChristoph Hellwig case ELEVATOR_DISCARD_MERGE:
1187eda5cc99SChristoph Hellwig return bio_attempt_discard_merge(q, rq, bio) == BIO_MERGE_OK;
1188eda5cc99SChristoph Hellwig default:
1189eda5cc99SChristoph Hellwig return false;
1190eda5cc99SChristoph Hellwig }
1191eda5cc99SChristoph Hellwig }
1192eda5cc99SChristoph Hellwig EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
1193