RDMA/srp: Increase max_segment_size (0b5cb330) · Commits · 戴 / test

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 ("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 <bvanassche@acm.org> Signed-off-by:

Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/ulp/srp/ib_srp.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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);

include/rdma/ib_verbs.h

+13 −0

Original line number	Diff line number	Diff line
		@@ -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

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