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NVMe: Handle physical merging of bvec entries 

In order to not overrun the sg array, we have to merge physically
contiguous pages into a single sg entry.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
This commit is contained in:
Matthew Wilcox 2011-02-10 13:55:39 -05:00
parent 1974b1ae88
commit 768308400f
1 changed files with 15 additions and 9 deletions
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24
drivers/block/nvme.c
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@ -392,19 +392,25 @@ static struct nvme_prps *nvme_setup_prps(struct nvme_dev *dev,
static int nvme_map_bio(struct device *dev, struct nvme_bio *nbio,
struct bio *bio, enum dma_data_direction dma_dir, int psegs)
{
struct bio_vec *bvec;
struct scatterlist *sg = nbio->sg;
int i, nsegs;
struct bio_vec *bvec, *bvprv = NULL;
struct scatterlist *sg = NULL;
int i, nsegs = 0;
sg_init_table(sg, psegs);
sg_init_table(nbio->sg, psegs);
bio_for_each_segment(bvec, bio, i) {
sg_set_page(sg, bvec->bv_page, bvec->bv_len, bvec->bv_offset);
sg++;
/* XXX: handle non-mergable here */
nsegs++;
if (bvprv && BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) {
sg->length += bvec->bv_len;
} else {
/* Check bvprv && offset == 0 */
sg = sg ? sg + 1 : nbio->sg;
sg_set_page(sg, bvec->bv_page, bvec->bv_len,
bvec->bv_offset);
nsegs++;
}
bvprv = bvec;
}
nbio->nents = nsegs;
sg_mark_end(sg);
return dma_map_sg(dev, nbio->sg, nbio->nents, dma_dir);
}