cciss: factor out scatter gather chain block mapping code

cciss: factor out scatter gather chain block mapping code
Rationale is I want to use this code from the scsi half of the
driver.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 34 insertions, 29 deletions

diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index c0d794ce69c6..9e3af307aae1 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -301,6 +301,35 @@ clean:
         return NULL;
 }
 
+static void cciss_unmap_sg_chain_block(ctlr_info_t *h, CommandList_struct *c)
+{
+        SGDescriptor_struct *chain_sg;
+        u64bit temp64;
+
+        if (c->Header.SGTotal <= h->max_cmd_sgentries)
+                return;
+
+        chain_sg = &c->SG[h->max_cmd_sgentries - 1];
+        temp64.val32.lower = chain_sg->Addr.lower;
+        temp64.val32.upper = chain_sg->Addr.upper;
+        pci_unmap_single(h->pdev, temp64.val, chain_sg->Len, PCI_DMA_TODEVICE);
+}
+
+static void cciss_map_sg_chain_block(ctlr_info_t *h, CommandList_struct *c,
+        SGDescriptor_struct *chain_block, int len)
+{
+        SGDescriptor_struct *chain_sg;
+        u64bit temp64;
+
+        chain_sg = &c->SG[h->max_cmd_sgentries - 1];
+        chain_sg->Ext = CCISS_SG_CHAIN;
+        chain_sg->Len = len;
+        temp64.val = pci_map_single(h->pdev, chain_block, len,
+                                PCI_DMA_TODEVICE);
+        chain_sg->Addr.lower = temp64.val32.lower;
+        chain_sg->Addr.upper = temp64.val32.upper;
+}
+
 #include "cciss_scsi.c"         /* For SCSI tape support */
 
 static const char *raid_label[] = { "0", "4", "1(1+0)", "5", "5+1", "ADG",
@@ -1715,10 +1744,7 @@ static void cciss_softirq_done(struct request *rq)
         /* unmap the DMA mapping for all the scatter gather elements */
         for (i = 0; i < cmd->Header.SGList; i++) {
                 if (curr_sg[sg_index].Ext == CCISS_SG_CHAIN) {
-                        temp64.val32.lower = cmd->SG[i].Addr.lower;
-                        temp64.val32.upper = cmd->SG[i].Addr.upper;
-                        pci_unmap_single(h->pdev, temp64.val,
-                                cmd->SG[i].Len, PCI_DMA_TODEVICE);
+                        cciss_unmap_sg_chain_block(h, cmd);
                         /* Point to the next block */
                         curr_sg = h->cmd_sg_list[cmd->cmdindex];
                         sg_index = 0;
@@ -3122,7 +3148,6 @@ static void do_cciss_request(struct request_queue *q)
         SGDescriptor_struct *curr_sg;
         drive_info_struct *drv;
         int i, dir;
-        int nseg = 0;
         int sg_index = 0;
         int chained = 0;
 
@@ -3189,11 +3214,6 @@ static void do_cciss_request(struct request_queue *q)
         for (i = 0; i < seg; i++) {
                 if (((sg_index+1) == (h->max_cmd_sgentries)) &&
                         !chained && ((seg - i) > 1)) {
-                        nseg = seg - i;
-                        curr_sg[sg_index].Len = (nseg) *
-                                        sizeof(SGDescriptor_struct);
-                        curr_sg[sg_index].Ext = CCISS_SG_CHAIN;
-
                         /* Point to next chain block. */
                         curr_sg = h->cmd_sg_list[c->cmdindex];
                         sg_index = 0;
@@ -3206,27 +3226,12 @@ static void do_cciss_request(struct request_queue *q)
                 curr_sg[sg_index].Addr.lower = temp64.val32.lower;
                 curr_sg[sg_index].Addr.upper = temp64.val32.upper;
                 curr_sg[sg_index].Ext = 0;  /* we are not chaining */
-
                 ++sg_index;
         }
-
-        if (chained) {
-                int len;
-                dma_addr_t dma_addr;
-                curr_sg = c->SG;
-                sg_index = h->max_cmd_sgentries - 1;
-                len = curr_sg[sg_index].Len;
-                /* Setup pointer to next chain block.
-                 * Fill out last element in current chain
-                 * block with address of next chain block.
-                 */
-                temp64.val = pci_map_single(h->pdev,
-                                        h->cmd_sg_list[c->cmdindex], len,
-                                        PCI_DMA_TODEVICE);
-                dma_addr = temp64.val;
-                curr_sg[sg_index].Addr.lower = temp64.val32.lower;
-                curr_sg[sg_index].Addr.upper = temp64.val32.upper;
-        }
+        if (chained)
+                cciss_map_sg_chain_block(h, c, h->cmd_sg_list[c->cmdindex],
+                        (seg - (h->max_cmd_sgentries - 1)) *
+                                sizeof(SGDescriptor_struct));
 
         /* track how many SG entries we are using */
         if (seg > h->maxSG)