X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=block%2Fblk-merge.c;h=22467f475ab412c345379db97313414a19eaeb16;hb=b5420237ec817b0b5f729a674c81ace0865c3b3b;hp=d79a22f111d132f4820188429dc2c321d308c371;hpb=343917b410ba7250dbbe59a8330feffaf36eaab8;p=mirror_ubuntu-jammy-kernel.git diff --git a/block/blk-merge.c b/block/blk-merge.c index d79a22f111d1..22467f475ab4 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -161,6 +161,73 @@ static inline unsigned get_max_io_size(struct request_queue *q, return sectors; } +static unsigned get_max_segment_size(struct request_queue *q, + unsigned offset) +{ + unsigned long mask = queue_segment_boundary(q); + + /* default segment boundary mask means no boundary limit */ + if (mask == BLK_SEG_BOUNDARY_MASK) + return queue_max_segment_size(q); + + return min_t(unsigned long, mask - (mask & offset) + 1, + queue_max_segment_size(q)); +} + +/* + * Split the bvec @bv into segments, and update all kinds of + * variables. + */ +static bool bvec_split_segs(struct request_queue *q, struct bio_vec *bv, + unsigned *nsegs, unsigned *last_seg_size, + unsigned *front_seg_size, unsigned *sectors) +{ + unsigned len = bv->bv_len; + unsigned total_len = 0; + unsigned new_nsegs = 0, seg_size = 0; + + /* + * Multi-page bvec may be too big to hold in one segment, so the + * current bvec has to be splitted as multiple segments. + */ + while (len && new_nsegs + *nsegs < queue_max_segments(q)) { + seg_size = get_max_segment_size(q, bv->bv_offset + total_len); + seg_size = min(seg_size, len); + + new_nsegs++; + total_len += seg_size; + len -= seg_size; + + if ((bv->bv_offset + total_len) & queue_virt_boundary(q)) + break; + } + + if (!new_nsegs) + return !!len; + + /* update front segment size */ + if (!*nsegs) { + unsigned first_seg_size; + + if (new_nsegs == 1) + first_seg_size = get_max_segment_size(q, bv->bv_offset); + else + first_seg_size = queue_max_segment_size(q); + + if (*front_seg_size < first_seg_size) + *front_seg_size = first_seg_size; + } + + /* update other varibles */ + *last_seg_size = seg_size; + *nsegs += new_nsegs; + if (sectors) + *sectors += total_len >> 9; + + /* split in the middle of the bvec if len != 0 */ + return !!len; +} + static struct bio *blk_bio_segment_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, @@ -174,7 +241,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, struct bio *new = NULL; const unsigned max_sectors = get_max_io_size(q, bio); - bio_for_each_segment(bv, bio, iter) { + bio_for_each_bvec(bv, bio, iter) { /* * If the queue doesn't support SG gaps and adding this * offset would create a gap, disallow it. @@ -189,8 +256,12 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, */ if (nsegs < queue_max_segments(q) && sectors < max_sectors) { - nsegs++; - sectors = max_sectors; + /* split in the middle of bvec */ + bv.bv_len = (max_sectors - sectors) << 9; + bvec_split_segs(q, &bv, &nsegs, + &seg_size, + &front_seg_size, + §ors); } goto split; } @@ -206,21 +277,28 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bvprvp = &bvprv; sectors += bv.bv_len >> 9; + if (nsegs == 1 && seg_size > front_seg_size) + front_seg_size = seg_size; + continue; } new_segment: if (nsegs == queue_max_segments(q)) goto split; - if (nsegs == 1 && seg_size > front_seg_size) - front_seg_size = seg_size; - - nsegs++; bvprv = bv; bvprvp = &bvprv; - seg_size = bv.bv_len; - sectors += bv.bv_len >> 9; + if (bv.bv_offset + bv.bv_len <= PAGE_SIZE) { + nsegs++; + seg_size = bv.bv_len; + sectors += bv.bv_len >> 9; + if (nsegs == 1 && seg_size > front_seg_size) + front_seg_size = seg_size; + } else if (bvec_split_segs(q, &bv, &nsegs, &seg_size, + &front_seg_size, §ors)) { + goto split; + } } do_split = false; @@ -233,8 +311,6 @@ split: bio = new; } - if (nsegs == 1 && seg_size > front_seg_size) - front_seg_size = seg_size; bio->bi_seg_front_size = front_seg_size; if (seg_size > bio->bi_seg_back_size) bio->bi_seg_back_size = seg_size; @@ -272,6 +348,16 @@ void blk_queue_split(struct request_queue *q, struct bio **bio) /* there isn't chance to merge the splitted bio */ split->bi_opf |= REQ_NOMERGE; + /* + * Since we're recursing into make_request here, ensure + * that we mark this bio as already having entered the queue. + * If not, and the queue is going away, we can get stuck + * forever on waiting for the queue reference to drop. But + * that will never happen, as we're already holding a + * reference to it. + */ + bio_set_flag(*bio, BIO_QUEUE_ENTERED); + bio_chain(split, *bio); trace_block_split(q, split, (*bio)->bi_iter.bi_sector); generic_make_request(*bio); @@ -281,18 +367,20 @@ void blk_queue_split(struct request_queue *q, struct bio **bio) EXPORT_SYMBOL(blk_queue_split); static unsigned int __blk_recalc_rq_segments(struct request_queue *q, - struct bio *bio, - bool no_sg_merge) + struct bio *bio) { struct bio_vec bv, bvprv = { NULL }; int prev = 0; unsigned int seg_size, nr_phys_segs; + unsigned front_seg_size; struct bio *fbio, *bbio; struct bvec_iter iter; if (!bio) return 0; + front_seg_size = bio->bi_seg_front_size; + switch (bio_op(bio)) { case REQ_OP_DISCARD: case REQ_OP_SECURE_ERASE: @@ -306,14 +394,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, seg_size = 0; nr_phys_segs = 0; for_each_bio(bio) { - bio_for_each_segment(bv, bio, iter) { - /* - * If SG merging is disabled, each bio vector is - * a segment - */ - if (no_sg_merge) - goto new_segment; - + bio_for_each_bvec(bv, bio, iter) { if (prev) { if (seg_size + bv.bv_len > queue_max_segment_size(q)) @@ -323,23 +404,23 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, seg_size += bv.bv_len; bvprv = bv; + + if (nr_phys_segs == 1 && seg_size > + front_seg_size) + front_seg_size = seg_size; + continue; } new_segment: - if (nr_phys_segs == 1 && seg_size > - fbio->bi_seg_front_size) - fbio->bi_seg_front_size = seg_size; - - nr_phys_segs++; bvprv = bv; prev = 1; - seg_size = bv.bv_len; + bvec_split_segs(q, &bv, &nr_phys_segs, &seg_size, + &front_seg_size, NULL); } bbio = bio; } - if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) - fbio->bi_seg_front_size = seg_size; + fbio->bi_seg_front_size = front_seg_size; if (seg_size > bbio->bi_seg_back_size) bbio->bi_seg_back_size = seg_size; @@ -348,33 +429,16 @@ new_segment: void blk_recalc_rq_segments(struct request *rq) { - bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, - &rq->q->queue_flags); - - rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio, - no_sg_merge); + rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio); } void blk_recount_segments(struct request_queue *q, struct bio *bio) { - unsigned short seg_cnt; - - /* estimate segment number by bi_vcnt for non-cloned bio */ - if (bio_flagged(bio, BIO_CLONED)) - seg_cnt = bio_segments(bio); - else - seg_cnt = bio->bi_vcnt; - - if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) && - (seg_cnt < queue_max_segments(q))) - bio->bi_phys_segments = seg_cnt; - else { - struct bio *nxt = bio->bi_next; + struct bio *nxt = bio->bi_next; - bio->bi_next = NULL; - bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false); - bio->bi_next = nxt; - } + bio->bi_next = NULL; + bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio); + bio->bi_next = nxt; bio_set_flag(bio, BIO_SEG_VALID); } @@ -397,6 +461,54 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, return biovec_phys_mergeable(q, &end_bv, &nxt_bv); } +static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, + struct scatterlist *sglist) +{ + if (!*sg) + return sglist; + + /* + * If the driver previously mapped a shorter list, we could see a + * termination bit prematurely unless it fully inits the sg table + * on each mapping. We KNOW that there must be more entries here + * or the driver would be buggy, so force clear the termination bit + * to avoid doing a full sg_init_table() in drivers for each command. + */ + sg_unmark_end(*sg); + return sg_next(*sg); +} + +static unsigned blk_bvec_map_sg(struct request_queue *q, + struct bio_vec *bvec, struct scatterlist *sglist, + struct scatterlist **sg) +{ + unsigned nbytes = bvec->bv_len; + unsigned nsegs = 0, total = 0, offset = 0; + + while (nbytes > 0) { + unsigned seg_size; + struct page *pg; + unsigned idx; + + *sg = blk_next_sg(sg, sglist); + + seg_size = get_max_segment_size(q, bvec->bv_offset + total); + seg_size = min(nbytes, seg_size); + + offset = (total + bvec->bv_offset) % PAGE_SIZE; + idx = (total + bvec->bv_offset) / PAGE_SIZE; + pg = bvec_nth_page(bvec->bv_page, idx); + + sg_set_page(*sg, pg, seg_size, offset); + + total += seg_size; + nbytes -= seg_size; + nsegs++; + } + + return nsegs; +} + static inline void __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, struct scatterlist *sglist, struct bio_vec *bvprv, @@ -414,25 +526,12 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, (*sg)->length += nbytes; } else { new_segment: - if (!*sg) - *sg = sglist; - else { - /* - * If the driver previously mapped a shorter - * list, we could see a termination bit - * prematurely unless it fully inits the sg - * table on each mapping. We KNOW that there - * must be more entries here or the driver - * would be buggy, so force clear the - * termination bit to avoid doing a full - * sg_init_table() in drivers for each command. - */ - sg_unmark_end(*sg); - *sg = sg_next(*sg); - } - - sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); - (*nsegs)++; + if (bvec->bv_offset + bvec->bv_len <= PAGE_SIZE) { + *sg = blk_next_sg(sg, sglist); + sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); + (*nsegs) += 1; + } else + (*nsegs) += blk_bvec_map_sg(q, bvec, sglist, sg); } *bvprv = *bvec; } @@ -454,7 +553,7 @@ static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, int nsegs = 0; for_each_bio(bio) - bio_for_each_segment(bvec, bio, iter) + bio_for_each_bvec(bvec, bio, iter) __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, &nsegs);