[SCSI] Legacy MegaRAID: Fix READ CAPACITY

Some Legacy megaraid cards can't actually cope with the scatter/gather
version of the READ CAPACITY command (which is what we now send them
since altering all SCSI internal I/O to go via the block layer).  Fix
this (and a few other broken megaraid driver assumptions) by sending
the non-sg version of the command if the sg list only has a single
element.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 50 insertions, 20 deletions

diff --git a/drivers/scsi/megaraid.c b/drivers/scsi/megaraid.c
index 6f308ebe3e79..61a6fd810bb4 100644
--- a/drivers/scsi/megaraid.c
+++ b/drivers/scsi/megaraid.c
@@ -621,8 +621,6 @@ mega_build_cmd(adapter_t *adapter, Scsi_Cmnd *cmd, int *busy)
         if(islogical) {
                 switch (cmd->cmnd[0]) {
                 case TEST_UNIT_READY:
-                        memset(cmd->request_buffer, 0, cmd->request_bufflen);
-
 #if MEGA_HAVE_CLUSTERING
                         /*
                          * Do we support clustering and is the support enabled
@@ -652,11 +650,28 @@ mega_build_cmd(adapter_t *adapter, Scsi_Cmnd *cmd, int *busy)
                         return NULL;
 #endif
 
-                case MODE_SENSE:
+                case MODE_SENSE: {
+                        char *buf;
+
+                        if (cmd->use_sg) {
+                                struct scatterlist *sg;
+
+                                sg = (struct scatterlist *)cmd->request_buffer;
+                                buf = kmap_atomic(sg->page, KM_IRQ0) +
+                                        sg->offset;
+                        } else
+                                buf = cmd->request_buffer;
                         memset(cmd->request_buffer, 0, cmd->cmnd[4]);
+                        if (cmd->use_sg) {
+                                struct scatterlist *sg;
+
+                                sg = (struct scatterlist *)cmd->request_buffer;
+                                kunmap_atomic(buf - sg->offset, KM_IRQ0);
+                        }
                         cmd->result = (DID_OK << 16);
                         cmd->scsi_done(cmd);
                         return NULL;
+                }
 
                 case READ_CAPACITY:
                 case INQUIRY:
@@ -1685,14 +1700,23 @@ mega_rundoneq (adapter_t *adapter)
 static void
 mega_free_scb(adapter_t *adapter, scb_t *scb)
 {
+        unsigned long length;
+
         switch( scb->dma_type ) {
 
         case MEGA_DMA_TYPE_NONE:
                 break;
 
         case MEGA_BULK_DATA:
+                if (scb->cmd->use_sg == 0)
+                        length = scb->cmd->request_bufflen;
+                else {
+                        struct scatterlist *sgl =
+                                (struct scatterlist *)scb->cmd->request_buffer;
+                        length = sgl->length;
+                }
                 pci_unmap_page(adapter->dev, scb->dma_h_bulkdata,
-                        scb->cmd->request_bufflen, scb->dma_direction);
+                               length, scb->dma_direction);
                 break;
 
         case MEGA_SGLIST:
@@ -1741,6 +1765,7 @@ mega_build_sglist(adapter_t *adapter, scb_t *scb, u32 *buf, u32 *len)
         struct scatterlist      *sgl;
         struct page     *page;
         unsigned long   offset;
+        unsigned int    length;
         Scsi_Cmnd       *cmd;
         int     sgcnt;
         int     idx;
@@ -1748,14 +1773,23 @@ mega_build_sglist(adapter_t *adapter, scb_t *scb, u32 *buf, u32 *len)
         cmd = scb->cmd;
 
         /* Scatter-gather not used */
-        if( !cmd->use_sg ) {
-
-                page = virt_to_page(cmd->request_buffer);
-                offset = offset_in_page(cmd->request_buffer);
+        if( cmd->use_sg == 0 || (cmd->use_sg == 1 && 
+                                 !adapter->has_64bit_addr)) {
+
+                if (cmd->use_sg == 0) {
+                        page = virt_to_page(cmd->request_buffer);
+                        offset = offset_in_page(cmd->request_buffer);
+                        length = cmd->request_bufflen;
+                } else {
+                        sgl = (struct scatterlist *)cmd->request_buffer;
+                        page = sgl->page;
+                        offset = sgl->offset;
+                        length = sgl->length;
+                }
 
                 scb->dma_h_bulkdata = pci_map_page(adapter->dev,
                                                   page, offset,
-                                                  cmd->request_bufflen,
+                                                  length,
                                                   scb->dma_direction);
                 scb->dma_type = MEGA_BULK_DATA;
 
@@ -1765,14 +1799,14 @@ mega_build_sglist(adapter_t *adapter, scb_t *scb, u32 *buf, u32 *len)
                  */
                 if( adapter->has_64bit_addr ) {
                         scb->sgl64[0].address = scb->dma_h_bulkdata;
-                        scb->sgl64[0].length = cmd->request_bufflen;
+                        scb->sgl64[0].length = length;
                         *buf = (u32)scb->sgl_dma_addr;
-                        *len = (u32)cmd->request_bufflen;
+                        *len = (u32)length;
                         return 1;
                 }
                 else {
                         *buf = (u32)scb->dma_h_bulkdata;
-                        *len = (u32)cmd->request_bufflen;
+                        *len = (u32)length;
                 }
                 return 0;
         }
@@ -1791,27 +1825,23 @@ mega_build_sglist(adapter_t *adapter, scb_t *scb, u32 *buf, u32 *len)
 
         if( sgcnt > adapter->sglen ) BUG();
 
+        *len = 0;
+
         for( idx = 0; idx < sgcnt; idx++, sgl++ ) {
 
                 if( adapter->has_64bit_addr ) {
                         scb->sgl64[idx].address = sg_dma_address(sgl);
-                        scb->sgl64[idx].length = sg_dma_len(sgl);
+                        *len += scb->sgl64[idx].length = sg_dma_len(sgl);
                 }
                 else {
                         scb->sgl[idx].address = sg_dma_address(sgl);
-                        scb->sgl[idx].length = sg_dma_len(sgl);
+                        *len += scb->sgl[idx].length = sg_dma_len(sgl);
                 }
         }
 
         /* Reset pointer and length fields */
         *buf = scb->sgl_dma_addr;
 
-        /*
-         * For passthru command, dataxferlen must be set, even for commands
-         * with a sg list
-         */
-        *len = (u32)cmd->request_bufflen;
-
         /* Return count of SG requests */
         return sgcnt;
 }