From 0b5cb3300ae59ed7e93b465dfa2384a6a4df8eb4 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Tue, 22 Jan 2019 10:25:20 -0800 Subject: [PATCH] RDMA/srp: Increase max_segment_size The default behavior of the SCSI core is to set the block layer request queue parameter max_segment_size to 64 KB. That means that elements of scatterlists are limited to 64 KB. Since RDMA adapters support larger sizes, increase max_segment_size for the SRP initiator. Notes: - The SCSI max_segment_size parameter was introduced in kernel v5.0. See also commit 50c2e9107f17 ("scsi: introduce a max_segment_size host_template parameters"). - Some other block drivers already set max_segment_size to UINT_MAX, e.g. nbd and rbd. Signed-off-by: Bart Van Assche Signed-off-by: Jason Gunthorpe --- drivers/infiniband/ulp/srp/ib_srp.c | 1 + include/rdma/ib_verbs.h | 13 +++++++++++++ 2 files changed, 14 insertions(+) diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c index 0f855294ff3f..29fe46dbdbf1 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.c +++ b/drivers/infiniband/ulp/srp/ib_srp.c @@ -3823,6 +3823,7 @@ static ssize_t srp_create_target(struct device *dev, target_host->max_id = 1; target_host->max_lun = -1LL; target_host->max_cmd_len = sizeof ((struct srp_cmd *) (void *) 0L)->cdb; + target_host->max_segment_size = ib_dma_max_seg_size(ibdev); target = host_to_target(target_host); diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h index 94b6e1dd4dab..71ea144ec823 100644 --- a/include/rdma/ib_verbs.h +++ b/include/rdma/ib_verbs.h @@ -3715,6 +3715,19 @@ static inline unsigned int ib_sg_dma_len(struct ib_device *dev, return sg_dma_len(sg); } +/** + * ib_dma_max_seg_size - Return the size limit of a single DMA transfer + * @dev: The device to query + * + * The returned value represents a size in bytes. + */ +static inline unsigned int ib_dma_max_seg_size(struct ib_device *dev) +{ + struct device_dma_parameters *p = dev->dma_device->dma_parms; + + return p ? p->max_segment_size : UINT_MAX; +} + /** * ib_dma_sync_single_for_cpu - Prepare DMA region to be accessed by CPU * @dev: The device for which the DMA address was created