Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma

Pull rdma fix from Doug Ledford:
 "Fix for max sector calculation in iSER"

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma:
  IB/iser: Fix max_sectors calculation

1 files changed, 10 insertions, 4 deletions

diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.c b/drivers/infiniband/ulp/iser/iscsi_iser.c
index 80b6bedc172f..64b3d11dcf1e 100644
--- a/drivers/infiniband/ulp/iser/iscsi_iser.c
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.c
@@ -612,6 +612,7 @@ iscsi_iser_session_create(struct iscsi_endpoint *ep,
         struct Scsi_Host *shost;
         struct iser_conn *iser_conn = NULL;
         struct ib_conn *ib_conn;
+        u32 max_fr_sectors;
         u16 max_cmds;
 
         shost = iscsi_host_alloc(&iscsi_iser_sht, 0, 0);
@@ -632,7 +633,6 @@ iscsi_iser_session_create(struct iscsi_endpoint *ep,
                 iser_conn = ep->dd_data;
                 max_cmds = iser_conn->max_cmds;
                 shost->sg_tablesize = iser_conn->scsi_sg_tablesize;
-                shost->max_sectors = iser_conn->scsi_max_sectors;
 
                 mutex_lock(&iser_conn->state_mutex);
                 if (iser_conn->state != ISER_CONN_UP) {
@@ -657,8 +657,6 @@ iscsi_iser_session_create(struct iscsi_endpoint *ep,
                  */
                 shost->sg_tablesize = min_t(unsigned short, shost->sg_tablesize,
                         ib_conn->device->ib_device->attrs.max_fast_reg_page_list_len);
-                shost->max_sectors = min_t(unsigned int,
-                        1024, (shost->sg_tablesize * PAGE_SIZE) >> 9);
 
                 if (iscsi_host_add(shost,
                                    ib_conn->device->ib_device->dma_device)) {
@@ -672,6 +670,15 @@ iscsi_iser_session_create(struct iscsi_endpoint *ep,
                         goto free_host;
         }
 
+        /*
+         * FRs or FMRs can only map up to a (device) page per entry, but if the
+         * first entry is misaligned we'll end up using using two entries
+         * (head and tail) for a single page worth data, so we have to drop
+         * one segment from the calculation.
+         */
+        max_fr_sectors = ((shost->sg_tablesize - 1) * PAGE_SIZE) >> 9;
+        shost->max_sectors = min(iser_max_sectors, max_fr_sectors);
+
         if (cmds_max > max_cmds) {
                 iser_info("cmds_max changed from %u to %u\n",
                           cmds_max, max_cmds);
@@ -989,7 +996,6 @@ static struct scsi_host_template iscsi_iser_sht = {
         .queuecommand           = iscsi_queuecommand,
         .change_queue_depth     = scsi_change_queue_depth,
         .sg_tablesize           = ISCSI_ISER_DEF_SG_TABLESIZE,
-        .max_sectors            = ISER_DEF_MAX_SECTORS,
         .cmd_per_lun            = ISER_DEF_CMD_PER_LUN,
         .eh_abort_handler       = iscsi_eh_abort,
         .eh_device_reset_handler= iscsi_eh_device_reset,