sd: don't use scsi_setup_blk_pc_cmnd for discard requests

Simplify handling of discard requests by setting up the command directly
instead of initializing request fields and then calling
scsi_setup_blk_pc_cmnd to propagate the information into the command.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>

1 files changed, 31 insertions, 19 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index aefedf4fbb2b..03bed86b9fc9 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -691,8 +691,10 @@ static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode)
  * Will issue either UNMAP or WRITE SAME(16) depending on preference
  * indicated by target device.
  **/
-static int sd_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq)
+static int sd_setup_discard_cmnd(struct scsi_cmnd *cmd)
 {
+        struct request *rq = cmd->request;
+        struct scsi_device *sdp = cmd->device;
         struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
         sector_t sector = blk_rq_pos(rq);
         unsigned int nr_sectors = blk_rq_sectors(rq);
@@ -704,9 +706,6 @@ static int sd_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq)
 
         sector >>= ilog2(sdp->sector_size) - 9;
         nr_sectors >>= ilog2(sdp->sector_size) - 9;
-        rq->timeout = SD_TIMEOUT;
-
-        memset(rq->cmd, 0, rq->cmd_len);
 
         page = alloc_page(GFP_ATOMIC | __GFP_ZERO);
         if (!page)
@@ -716,9 +715,9 @@ static int sd_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq)
         case SD_LBP_UNMAP:
                 buf = page_address(page);
 
-                rq->cmd_len = 10;
-                rq->cmd[0] = UNMAP;
-                rq->cmd[8] = 24;
+                cmd->cmd_len = 10;
+                cmd->cmnd[0] = UNMAP;
+                cmd->cmnd[8] = 24;
 
                 put_unaligned_be16(6 + 16, &buf[0]);
                 put_unaligned_be16(16, &buf[2]);
@@ -729,23 +728,23 @@ static int sd_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq)
                 break;
 
         case SD_LBP_WS16:
-                rq->cmd_len = 16;
-                rq->cmd[0] = WRITE_SAME_16;
-                rq->cmd[1] = 0x8; /* UNMAP */
-                put_unaligned_be64(sector, &rq->cmd[2]);
-                put_unaligned_be32(nr_sectors, &rq->cmd[10]);
+                cmd->cmd_len = 16;
+                cmd->cmnd[0] = WRITE_SAME_16;
+                cmd->cmnd[1] = 0x8; /* UNMAP */
+                put_unaligned_be64(sector, &cmd->cmnd[2]);
+                put_unaligned_be32(nr_sectors, &cmd->cmnd[10]);
 
                 len = sdkp->device->sector_size;
                 break;
 
         case SD_LBP_WS10:
         case SD_LBP_ZERO:
-                rq->cmd_len = 10;
-                rq->cmd[0] = WRITE_SAME;
+                cmd->cmd_len = 10;
+                cmd->cmnd[0] = WRITE_SAME;
                 if (sdkp->provisioning_mode == SD_LBP_WS10)
-                        rq->cmd[1] = 0x8; /* UNMAP */
-                put_unaligned_be32(sector, &rq->cmd[2]);
-                put_unaligned_be16(nr_sectors, &rq->cmd[7]);
+                        cmd->cmnd[1] = 0x8; /* UNMAP */
+                put_unaligned_be32(sector, &cmd->cmnd[2]);
+                put_unaligned_be16(nr_sectors, &cmd->cmnd[7]);
 
                 len = sdkp->device->sector_size;
                 break;
@@ -756,8 +755,21 @@ static int sd_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq)
         }
 
         rq->completion_data = page;
+        rq->timeout = SD_TIMEOUT;
+
+        cmd->transfersize = len;
+        cmd->allowed = rq->retries;
+
+        /*
+         * Initially __data_len is set to the amount of data that needs to be
+         * transferred to the target. This amount depends on whether WRITE SAME
+         * or UNMAP is being used. After the scatterlist has been mapped by
+         * scsi_init_io() we set __data_len to the size of the area to be
+         * discarded on disk. This allows us to report completion on the full
+         * amount of blocks described by the request.
+         */
         blk_add_request_payload(rq, page, len);
-        ret = scsi_setup_blk_pc_cmnd(sdp, rq);
+        ret = scsi_init_io(cmd, GFP_ATOMIC);
         rq->__data_len = nr_bytes;
 
 out:
@@ -903,7 +915,7 @@ static int sd_init_command(struct scsi_cmnd *SCpnt)
          * block PC requests to make life easier.
          */
         if (rq->cmd_flags & REQ_DISCARD) {
-                ret = sd_setup_discard_cmnd(sdp, rq);
+                ret = sd_setup_discard_cmnd(SCpnt);
                 goto out;
         } else if (rq->cmd_flags & REQ_WRITE_SAME) {
                 ret = sd_setup_write_same_cmnd(SCpnt);