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Commit 0b5cb330 authored by Bart Van Assche's avatar Bart Van Assche Committed by Jason Gunthorpe
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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 50c2e910 ("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: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
parent db421a54

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