[PATCH 3/4] nvme-pci: use max of PRP or SGL for iod size

[Chaitanya Kulkarni]

>From the initial implementation of NVMe SGL kernel support
commit a7a7cbe353a5 ("nvme-pci: add SGL support") with addition of the
commit 943e942e6266 ("nvme-pci: limit max IO size and segments to avoid
high order allocations") now there is only caller left for
nvme_pci_iod_alloc_size() which statically passes true for last
parameter that calculates allocation size based on SGL since we need
size of biggest command supported for mempool allocation.

This patch modifies the helper functions nvme_pci_iod_alloc_size() such
that it is now uses maximum of PRP and SGL size for iod allocation size
calculation.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
---
 drivers/nvme/host/pci.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index cef87ad2323f..0588bd053a2a 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -370,14 +370,13 @@ static int nvme_pci_npages_sgl(unsigned int num_seg)
 }
 
 static size_t nvme_pci_iod_alloc_size(struct nvme_dev *dev,
-		unsigned int size, unsigned int nseg, bool use_sgl)
+		unsigned int size, unsigned int nseg)
 {
-	size_t alloc_size;
+	size_t npages_sgl = nvme_pci_npages_sgl(nseg);
+	size_t npages = nvme_npages(size, dev);
+	size_t alloc_size = sizeof(__le64 *);
 
-	if (use_sgl)
-		alloc_size = sizeof(__le64 *) * nvme_pci_npages_sgl(nseg);
-	else
-		alloc_size = sizeof(__le64 *) * nvme_npages(size, dev);
+	alloc_size *= (npages_sgl > npages ? npages_sgl : npages);
 
 	return alloc_size + sizeof(struct scatterlist) * nseg;
 }
@@ -2819,7 +2818,7 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	 * command we support.
 	 */
 	alloc_size = nvme_pci_iod_alloc_size(dev, NVME_MAX_KB_SZ,
-						NVME_MAX_SEGS, true);
+						NVME_MAX_SEGS);
 	WARN_ON_ONCE(alloc_size > PAGE_SIZE);
 
 	dev->iod_mempool = mempool_create_node(1, mempool_kmalloc,
-- 
2.26.0