diff options
| -rw-r--r-- | block/blk-merge.c | 54 |
1 files changed, 49 insertions, 5 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c index a476337a8ff4..ca2e7aec8e77 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -109,6 +109,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bool do_split = true; struct bio *new = NULL; const unsigned max_sectors = get_max_io_size(q, bio); + unsigned advance = 0; bio_for_each_segment(bv, bio, iter) { /* @@ -134,12 +135,32 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, } if (bvprvp && blk_queue_cluster(q)) { - if (seg_size + bv.bv_len > queue_max_segment_size(q)) - goto new_segment; if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv)) goto new_segment; if (!BIOVEC_SEG_BOUNDARY(q, bvprvp, &bv)) goto new_segment; + if (seg_size + bv.bv_len > queue_max_segment_size(q)) { + /* + * One assumption is that initial value of + * @seg_size(equals to bv.bv_len) won't be + * bigger than max segment size, but this + * becomes false after multipage bvecs. + */ + advance = queue_max_segment_size(q) - seg_size; + + if (advance > 0) { + seg_size += advance; + sectors += advance >> 9; + bv.bv_len -= advance; + bv.bv_offset += advance; + } + + /* + * Still need to put remainder of current + * bvec into a new segment. + */ + goto new_segment; + } seg_size += bv.bv_len; bvprv = bv; @@ -161,6 +182,12 @@ new_segment: seg_size = bv.bv_len; sectors += bv.bv_len >> 9; + /* restore the bvec for iterator */ + if (advance) { + bv.bv_len += advance; + bv.bv_offset -= advance; + advance = 0; + } } do_split = false; @@ -361,16 +388,29 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, { int nbytes = bvec->bv_len; + unsigned advance = 0; if (*sg && *cluster) { - if ((*sg)->length + nbytes > queue_max_segment_size(q)) - goto new_segment; - if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) goto new_segment; if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) goto new_segment; + /* + * try best to merge part of the bvec into previous + * segment and follow same policy with + * blk_bio_segment_split() + */ + if ((*sg)->length + nbytes > queue_max_segment_size(q)) { + advance = queue_max_segment_size(q) - (*sg)->length; + if (advance) { + (*sg)->length += advance; + bvec->bv_offset += advance; + bvec->bv_len -= advance; + } + goto new_segment; + } + (*sg)->length += nbytes; } else { new_segment: @@ -393,6 +433,10 @@ new_segment: sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); (*nsegs)++; + + /* for making iterator happy */ + bvec->bv_offset -= advance; + bvec->bv_len += advance; } *bvprv = *bvec; } |