vhost/scsi: increase VHOST_SCSI_PREALLOC_PROT_SGLS to 2048

The current value of VHOST_SCSI_PREALLOC_PROT_SGLS is too small to
accommodate larger I/Os, e.g. 16-32 MiB, when the VIRTIO_SCSI_F_T10_PI
feature bit is negotiated and the backing store supports T10 PI.

vhost-scsi rejects the command with errors like:

[   59.581317] vhost_scsi_calc_sgls: requested sgl_count: 1820 exceeds pre-allocated max_sgls: 512
Signed-off-by: Greg Edwards <gedwards@ddn.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/scsi.c

@@ -56,7 +56,7 @@
 #define VHOST_SCSI_DEFAULT_TAGS 256
 #define VHOST_SCSI_PREALLOC_SGLS 2048
 #define VHOST_SCSI_PREALLOC_UPAGES 2048
-#define VHOST_SCSI_PREALLOC_PROT_SGLS 512
+#define VHOST_SCSI_PREALLOC_PROT_SGLS 2048
 
 struct vhost_scsi_inflight {
 	/* Wait for the flush operation to finish */