Commit b0f2853b authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

nvme-pci: take sglist coalescing in dma_map_sg into account

Some iommu implementations can merge physically and/or virtually
contiguous segments inside sg_map_dma.  The NVMe SGL support does not take
this into account and will warn because of falling off a loop.  Pass the
number of mapped segments to nvme_pci_setup_sgls so that the SGL setup
can take the number of mapped segments into account.
Reported-by: default avatarFangjian (Turing) <>
Fixes: a7a7cbe3

 ("nvme-pci: add SGL support")
Signed-off-by: default avatarChristoph Hellwig <>
Reviewed-by: default avatarKeith Busch <>
Reviewed-by: default avatarSagi Grimberg <>
Signed-off-by: default avatarJens Axboe <>
parent 20469a37
......@@ -725,20 +725,19 @@ static void nvme_pci_sgl_set_seg(struct nvme_sgl_desc *sge,
static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,
struct request *req, struct nvme_rw_command *cmd)
struct request *req, struct nvme_rw_command *cmd, int entries)
struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
int length = blk_rq_payload_bytes(req);
struct dma_pool *pool;
struct nvme_sgl_desc *sg_list;
struct scatterlist *sg = iod->sg;
int entries = iod->nents, i = 0;
dma_addr_t sgl_dma;
int i = 0;
/* setting the transfer type as SGL */
cmd->flags = NVME_CMD_SGL_METABUF;
if (length == sg_dma_len(sg)) {
if (entries == 1) {
nvme_pci_sgl_set_data(&cmd->dptr.sgl, sg);
return BLK_STS_OK;
......@@ -778,13 +777,9 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,
nvme_pci_sgl_set_data(&sg_list[i++], sg);
length -= sg_dma_len(sg);
sg = sg_next(sg);
} while (length > 0);
} while (--entries > 0);
WARN_ON(entries > 0);
return BLK_STS_OK;
......@@ -796,6 +791,7 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
enum dma_data_direction dma_dir = rq_data_dir(req) ?
blk_status_t ret = BLK_STS_IOERR;
int nr_mapped;
sg_init_table(iod->sg, blk_rq_nr_phys_segments(req));
iod->nents = blk_rq_map_sg(q, req, iod->sg);
......@@ -803,12 +799,13 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
goto out;
if (!dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, dma_dir,
nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, dma_dir,
if (!nr_mapped)
goto out;
if (iod->use_sgl)
ret = nvme_pci_setup_sgls(dev, req, &cmnd->rw);
ret = nvme_pci_setup_sgls(dev, req, &cmnd->rw, nr_mapped);
ret = nvme_pci_setup_prps(dev, req, &cmnd->rw);
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