From: Leon Romanovsky <leonro@xxxxxxxxxx>
Calculate the number of DMA entries for each command in the request in
advance.
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>
---
drivers/nvme/host/pci.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index a9a66f184138..2b236b1d209e 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -231,6 +231,7 @@ struct nvme_iod {
struct nvme_request req;
struct nvme_command cmd;
bool aborted;
+ u8 nr_dmas;
s8 nr_allocations; /* PRP list pool allocations. 0 means small
pool in use */
dma_addr_t first_dma;
@@ -766,6 +767,23 @@ static blk_status_t nvme_map_metadata(struct nvme_dev *dev, struct request *req,
return BLK_STS_OK;
}
+static u8 nvme_calc_num_dmas(struct request *req)
+{
+ struct bio_vec bv;
+ u8 nr_dmas;
+
+ if (blk_rq_nr_phys_segments(req) == 0)
+ return 0;
+
+ nr_dmas = DIV_ROUND_UP(blk_rq_payload_bytes(req), NVME_CTRL_PAGE_SIZE);
+ bv = req_bvec(req);
+ if (bv.bv_offset && (bv.bv_offset + bv.bv_len) >= NVME_CTRL_PAGE_SIZE)
+ /* Accommodate for unaligned first page */
+ nr_dmas++;
+
+ return nr_dmas;
+}
+
static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req)
{
struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
@@ -779,6 +797,8 @@ static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req)
if (ret)
return ret;
+ iod->nr_dmas = nvme_calc_num_dmas(req);
+
if (blk_rq_nr_phys_segments(req)) {
ret = nvme_map_data(dev, req, &iod->cmd);
if (ret)
--
2.46.0
