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nvme-pci: iod npages fits in s8 

The largest allowed transfer is 4MB, which can use at most 1025 PRPs.
Each PRP is 8 bytes, so the maximum number of 4k nvme pages needed for
the iod_list is 3, which fits in an 's8' type.

While modifying this field, change the name to "nr_allocations" to
better represent that this is referring to the number of units allocated
from a dma_pool.

Also introduce a BUILD_BUG_ON to ensure we never accidently increase the
largest transfer limit beyond 127 chained prp lists.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Keith Busch 2022-09-06 09:07:37 -07:00 committed by Christoph Hellwig
parent 52da4f3f5c
commit c372cdd1ef
1 changed files with 16 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
drivers/nvme/host/pci.c
View File

@ -228,7 +228,8 @@ struct nvme_iod {
struct nvme_command cmd;
bool use_sgl;
bool aborted;
int npages; /* In the PRP list. 0 means small pool in use */
s8 nr_allocations; /* PRP list pool allocations. 0 means small
pool in use */
dma_addr_t first_dma;
unsigned int dma_len; /* length of single DMA segment mapping */
dma_addr_t meta_dma;
@ -542,7 +543,7 @@ static void nvme_free_prps(struct nvme_dev *dev, struct request *req)
dma_addr_t dma_addr = iod->first_dma;
int i;
for (i = 0; i < iod->npages; i++) {
for (i = 0; i < iod->nr_allocations; i++) {
__le64 *prp_list = nvme_pci_iod_list(req)[i];
dma_addr_t next_dma_addr = le64_to_cpu(prp_list[last_prp]);
@ -558,7 +559,7 @@ static void nvme_free_sgls(struct nvme_dev *dev, struct request *req)
dma_addr_t dma_addr = iod->first_dma;
int i;
for (i = 0; i < iod->npages; i++) {
for (i = 0; i < iod->nr_allocations; i++) {
struct nvme_sgl_desc *sg_list = nvme_pci_iod_list(req)[i];
dma_addr_t next_dma_addr = le64_to_cpu((sg_list[last_sg]).addr);
@ -581,7 +582,7 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
dma_unmap_sgtable(dev->dev, &iod->sgt, rq_dma_dir(req), 0);
if (iod->npages == 0)
if (iod->nr_allocations == 0)
dma_pool_free(dev->prp_small_pool, nvme_pci_iod_list(req)[0],
iod->first_dma);
else if (iod->use_sgl)
@ -643,15 +644,15 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
nprps = DIV_ROUND_UP(length, NVME_CTRL_PAGE_SIZE);
if (nprps <= (256 / 8)) {
pool = dev->prp_small_pool;
iod->npages = 0;
iod->nr_allocations = 0;
} else {
pool = dev->prp_page_pool;
iod->npages = 1;
iod->nr_allocations = 1;
}
prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
if (!prp_list) {
iod->npages = -1;
iod->nr_allocations = -1;
return BLK_STS_RESOURCE;
}
list[0] = prp_list;
@ -663,7 +664,7 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
if (!prp_list)
goto free_prps;
list[iod->npages++] = prp_list;
list[iod->nr_allocations++] = prp_list;
prp_list[0] = old_prp_list[i - 1];
old_prp_list[i - 1] = cpu_to_le64(prp_dma);
i = 1;
@ -738,15 +739,15 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,
if (entries <= (256 / sizeof(struct nvme_sgl_desc))) {
pool = dev->prp_small_pool;
iod->npages = 0;
iod->nr_allocations = 0;
} else {
pool = dev->prp_page_pool;
iod->npages = 1;
iod->nr_allocations = 1;
}
sg_list = dma_pool_alloc(pool, GFP_ATOMIC, &sgl_dma);
if (!sg_list) {
iod->npages = -1;
iod->nr_allocations = -1;
return BLK_STS_RESOURCE;
}
@ -765,7 +766,7 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,
goto free_sgls;
i = 0;
nvme_pci_iod_list(req)[iod->npages++] = sg_list;
nvme_pci_iod_list(req)[iod->nr_allocations++] = sg_list;
sg_list[i++] = *link;
nvme_pci_sgl_set_seg(link, sgl_dma, entries);
}
@ -892,7 +893,7 @@ static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req)
blk_status_t ret;
iod->aborted = false;
iod->npages = -1;
iod->nr_allocations = -1;
iod->sgt.nents = 0;
ret = nvme_setup_cmd(req->q->queuedata, req);
@ -3559,6 +3560,8 @@ static int __init nvme_init(void)
BUILD_BUG_ON(sizeof(struct nvme_create_sq) != 64);
BUILD_BUG_ON(sizeof(struct nvme_delete_queue) != 64);
BUILD_BUG_ON(IRQ_AFFINITY_MAX_SETS < 2);
BUILD_BUG_ON(DIV_ROUND_UP(nvme_pci_npages_prp(), NVME_CTRL_PAGE_SIZE) >
S8_MAX);
return pci_register_driver(&nvme_driver);
}