On Fri, Apr 22, 2016 at 02:16:31PM -0700, Bart Van Assche wrote:
> If both max_sectors and the queue_depth are high enough it can
> happen that the MR pool is depleted temporarily. This causes
> the SRP initiator to report mapping failures. Although the SRP
> initiator recovers from such mapping failures, prevent that
> this can happen by limiting max_sectors.
>
> Reported-by: Laurence Oberman <loberman@xxxxxxxxxx>
> Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Sagi Grimberg <sagi@xxxxxxxxxxx>
> ---
> drivers/infiniband/ulp/srp/ib_srp.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
> index a173ec4..ebd4d90 100644
> --- a/drivers/infiniband/ulp/srp/ib_srp.c
> +++ b/drivers/infiniband/ulp/srp/ib_srp.c
> @@ -3172,6 +3172,7 @@ static ssize_t srp_create_target(struct device *dev,
> struct srp_device *srp_dev = host->srp_dev;
> struct ib_device *ibdev = srp_dev->dev;
> int ret, node_idx, node, cpu, i;
> + unsigned int max_max_sectors;
> bool multich = false;
>
> target_host = scsi_host_alloc(&srp_template,
> @@ -3228,6 +3229,25 @@ static ssize_t srp_create_target(struct device *dev,
> target->sg_tablesize = target->cmd_sg_cnt;
> }
>
> + if (srp_dev->use_fast_reg || srp_dev->use_fmr) {
> + /*
> + * FR and FMR can only map one HCA page per entry. If the
> + * start address is not aligned on a HCA page boundary two
> + * entries will be used for the head and the tail although
> + * these two entries combined contain at most one HCA page of
> + * data. Hence the "- 1" in the calculation below.
> + */
> + max_max_sectors = (srp_dev->max_pages_per_mr - 1) <<
> + (ilog2(srp_dev->mr_page_size) - 9);
From my understanding, srp_dev->max_pages_per_mr can be equal to 1, in
case device will advertise it.
Is this understanding correct?
Will the code work in such case?
> + if (target->scsi_host->max_sectors > max_max_sectors) {
> + shost_printk(KERN_WARNING, target->scsi_host,
> + PFX "Reducing max_sectors from %d to %d\n",
> + target->scsi_host->max_sectors,
> + max_max_sectors);
> + target->scsi_host->max_sectors = max_max_sectors;
> + }
> + }
> +
> target_host->sg_tablesize = target->sg_tablesize;
> target->mr_pool_size = target->scsi_host->can_queue;
> target->indirect_size = target->sg_tablesize *
> --
> 2.8.1
>
> --
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