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;
+ bool new_bio = false;
if (!bio)
return 0;
nr_phys_segs = 0;
for_each_bio(bio) {
bio_for_each_bvec(bv, bio, iter) {
- if (prev) {
+ if (new_bio) {
if (seg_size + bv.bv_len
> queue_max_segment_size(q))
goto new_segment;
goto new_segment;
seg_size += bv.bv_len;
- bvprv = bv;
if (nr_phys_segs == 1 && seg_size >
front_seg_size)
continue;
}
new_segment:
- bvprv = bv;
- prev = 1;
bvec_split_segs(q, &bv, &nr_phys_segs, &seg_size,
&front_seg_size, NULL, UINT_MAX);
+ new_bio = false;
}
bbio = bio;
+ bvprv = bv;
+ new_bio = true;
}
fbio->bi_seg_front_size = front_seg_size;
return 1;
}
-static inline void
-__blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec,
- struct scatterlist *sglist, struct bio_vec *bvprv,
- struct scatterlist **sg, int *nsegs)
+/* only try to merge bvecs into one sg if they are from two bios */
+static inline bool
+__blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec,
+ struct bio_vec *bvprv, struct scatterlist **sg)
{
int nbytes = bvec->bv_len;
- if (*sg) {
- if ((*sg)->length + nbytes > queue_max_segment_size(q))
- goto new_segment;
- if (!biovec_phys_mergeable(q, bvprv, bvec))
- goto new_segment;
+ if (!*sg)
+ return false;
- (*sg)->length += nbytes;
- } else {
-new_segment:
- if (bvec->bv_offset + bvec->bv_len <= PAGE_SIZE) {
- (*nsegs) += __blk_bvec_map_sg(*bvec, sglist, sg);
- } else
- (*nsegs) += blk_bvec_map_sg(q, bvec, sglist, sg);
- }
- *bvprv = *bvec;
+ if ((*sg)->length + nbytes > queue_max_segment_size(q))
+ return false;
+
+ if (!biovec_phys_mergeable(q, bvprv, bvec))
+ return false;
+
+ (*sg)->length += nbytes;
+
+ return true;
}
static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio,
struct bio_vec bvec, bvprv = { NULL };
struct bvec_iter iter;
int nsegs = 0;
+ bool new_bio = false;
- for_each_bio(bio)
- bio_for_each_bvec(bvec, bio, iter)
- __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg,
- &nsegs);
+ for_each_bio(bio) {
+ bio_for_each_bvec(bvec, bio, iter) {
+ /*
+ * Only try to merge bvecs from two bios given we
+ * have done bio internal merge when adding pages
+ * to bio
+ */
+ if (new_bio &&
+ __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg))
+ goto next_bvec;
+
+ if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE)
+ nsegs += __blk_bvec_map_sg(bvec, sglist, sg);
+ else
+ nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg);
+ next_bvec:
+ new_bio = false;
+ }
+ bvprv = bvec;
+ new_bio = true;
+ }
return nsegs;
}