Commit 5ae6a6a9 authored May 22, 2020 by Sudhakar Panneerselvam Committed by Martin K. Petersen May 26, 2020

scsi: vhost: Notify TCM about the maximum sg entries supported per command

vhost-scsi pre-allocates the maximum sg entries per command and if a
command requires more than VHOST_SCSI_PREALLOC_SGLS entries, then that
command is failed by it. This patch lets vhost communicate the max sg limit
when it registers vhost_scsi_ops with TCM. With this change, TCM would
report the max sg entries through "Block Limits" VPD page which will be
typically queried by the SCSI initiator during device discovery. By knowing
this limit, the initiator could ensure the maximum transfer length is less
than or equal to what is reported by vhost-scsi.

Link: https://lore.kernel.org/r/1590166317-953-1-git-send-email-sudhakar.panneerselvam@oracle.com

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Sudhakar Panneerselvam <sudhakar.panneerselvam@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

parent ac988c49

drivers/vhost/scsi.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -2280,6 +2280,7 @@ static struct configfs_attribute *vhost_scsi_wwn_attrs[] = {
		static const struct target_core_fabric_ops vhost_scsi_ops = {
		.module = THIS_MODULE,
		.fabric_name = "vhost",
		.max_data_sg_nents = VHOST_SCSI_PREALLOC_SGLS,
		.tpg_get_wwn = vhost_scsi_get_fabric_wwn,
		.tpg_get_tag = vhost_scsi_get_tpgt,
		.tpg_check_demo_mode = vhost_scsi_check_true,

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