On Wed, Aug 28, 2019 at 05:20:57PM +0800, Ming Lei wrote:
> On Thu, Mar 21, 2019 at 04:10:32PM -0700, Christoph Hellwig wrote:
> > We always have exactly one segment, so we can simply call dma_map_bvec.
> >
> > Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> > ---
> > drivers/nvme/host/pci.c | 23 ++++++++++-------------
> > 1 file changed, 10 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> > index bc4ee869fe82..a7dad24e0406 100644
> > --- a/drivers/nvme/host/pci.c
> > +++ b/drivers/nvme/host/pci.c
> > @@ -221,7 +221,7 @@ struct nvme_iod {
> > int npages; /* In the PRP list. 0 means small pool in use */
> > int nents; /* Used in scatterlist */
> > dma_addr_t first_dma;
> > - struct scatterlist meta_sg; /* metadata requires single contiguous buffer */
> > + dma_addr_t meta_dma;
> > struct scatterlist *sg;
> > struct scatterlist inline_sg[0];
> > };
> > @@ -592,13 +592,16 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
> > dma_addr_t dma_addr = iod->first_dma, next_dma_addr;
> > int i;
> >
> > + if (blk_integrity_rq(req)) {
> > + dma_unmap_page(dev->dev, iod->meta_dma,
> > + rq_integrity_vec(req)->bv_len, dma_dir);
> > + }
> > +
> > if (iod->nents) {
> > /* P2PDMA requests do not need to be unmapped */
> > if (!is_pci_p2pdma_page(sg_page(iod->sg)))
> > dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
> >
> > - if (blk_integrity_rq(req))
> > - dma_unmap_sg(dev->dev, &iod->meta_sg, 1, dma_dir);
> > }
> >
> > if (iod->npages == 0)
> > @@ -861,17 +864,11 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
> >
> > ret = BLK_STS_IOERR;
> > if (blk_integrity_rq(req)) {
> > - if (blk_rq_count_integrity_sg(q, req->bio) != 1)
> > - goto out;
> > -
> > - sg_init_table(&iod->meta_sg, 1);
> > - if (blk_rq_map_integrity_sg(q, req->bio, &iod->meta_sg) != 1)
> > - goto out;
> > -
> > - if (!dma_map_sg(dev->dev, &iod->meta_sg, 1, dma_dir))
> > + iod->meta_dma = dma_map_bvec(dev->dev, rq_integrity_vec(req),
> > + dma_dir, 0);
>
> Hi Christoph,
>
> When one bio is enough big, the generated integrity data could cross
> more than one pages even though the data is still in single segment.
>
> However, we don't convert to multi-page bvec for bio_integrity_prep(),
> and each page may consume one bvec, so is it possible for this patch to
> cause issues in case of NVMe's protection? Since this patch supposes
> that there is only one bvec for integrity data.
>
> BTW, not see such kind of report, just a concern in theory.
Hello Christoph,
Gently ping...
Thanks,
Ming
