[SCSI] move ULD attachment into the prep function

One of the intents of the block prep function was to allow ULDs to use
it for preprocessing.  The original SCSI model was to have a single prep
function and add a pointer indirect filter to build the necessary
commands.  This patch reverses that, does away with the init_command
field of the scsi_driver structure and makes ULDs attach directly to the
prep function instead.  The value is really that it allows us to begin
to separate the ULDs from the SCSI mid layer (as long as they don't use
any core functions---which is hard at the moment---a ULD doesn't even
need SCSI to bind).

Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 34 insertions, 14 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 2c6116fd4578..38a41415004b 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -240,7 +240,6 @@ static struct scsi_driver sd_template = {
                 .shutdown       = sd_shutdown,
         },
         .rescan                 = sd_rescan,
-        .init_command           = sd_init_command,
 };
 
 /*
@@ -331,14 +330,31 @@ static void scsi_disk_put(struct scsi_disk *sdkp)
  *
  *      Returns 1 if successful and 0 if error (or cannot be done now).
  **/
-static int sd_init_command(struct scsi_cmnd * SCpnt)
+static int sd_prep_fn(struct request_queue *q, struct request *rq)
 {
-        struct scsi_device *sdp = SCpnt->device;
-        struct request *rq = SCpnt->request;
+        struct scsi_cmnd *SCpnt;
+        struct scsi_device *sdp = q->queuedata;
         struct gendisk *disk = rq->rq_disk;
         sector_t block = rq->sector;
-        unsigned int this_count = SCpnt->request_bufflen >> 9;
+        unsigned int this_count = rq->nr_sectors;
         unsigned int timeout = sdp->timeout;
+        int ret;
+
+        if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
+                ret = scsi_setup_blk_pc_cmnd(sdp, rq);
+                goto out;
+        } else if (rq->cmd_type != REQ_TYPE_FS) {
+                ret = BLKPREP_KILL;
+                goto out;
+        }
+        ret = scsi_setup_fs_cmnd(sdp, rq);
+        if (ret != BLKPREP_OK)
+                goto out;
+        SCpnt = rq->special;
+
+        /* from here on until we're complete, any goto out
+         * is used for a killable error condition */
+        ret = BLKPREP_KILL;
 
         SCSI_LOG_HLQUEUE(1, scmd_printk(KERN_INFO, SCpnt,
                                         "sd_init_command: block=%llu, "
@@ -353,7 +369,7 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
                                                 rq->nr_sectors));
                 SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt,
                                                 "Retry with 0x%p\n", SCpnt));
-                return 0;
+                goto out;
         }
 
         if (sdp->changed) {
@@ -362,8 +378,9 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
                  * the changed bit has been reset
                  */
                 /* printk("SCSI disk has been changed. Prohibiting further I/O.\n"); */
-                return 0;
+                goto out;
         }
+
         SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt, "block=%llu\n",
                                         (unsigned long long)block));
 
@@ -382,7 +399,7 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
                 if ((block & 1) || (rq->nr_sectors & 1)) {
                         scmd_printk(KERN_ERR, SCpnt,
                                     "Bad block number requested\n");
-                        return 0;
+                        goto out;
                 } else {
                         block = block >> 1;
                         this_count = this_count >> 1;
@@ -392,7 +409,7 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
                 if ((block & 3) || (rq->nr_sectors & 3)) {
                         scmd_printk(KERN_ERR, SCpnt,
                                     "Bad block number requested\n");
-                        return 0;
+                        goto out;
                 } else {
                         block = block >> 2;
                         this_count = this_count >> 2;
@@ -402,7 +419,7 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
                 if ((block & 7) || (rq->nr_sectors & 7)) {
                         scmd_printk(KERN_ERR, SCpnt,
                                     "Bad block number requested\n");
-                        return 0;
+                        goto out;
                 } else {
                         block = block >> 3;
                         this_count = this_count >> 3;
@@ -410,7 +427,7 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
         }
         if (rq_data_dir(rq) == WRITE) {
                 if (!sdp->writeable) {
-                        return 0;
+                        goto out;
                 }
                 SCpnt->cmnd[0] = WRITE_6;
                 SCpnt->sc_data_direction = DMA_TO_DEVICE;
@@ -419,7 +436,7 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
                 SCpnt->sc_data_direction = DMA_FROM_DEVICE;
         } else {
                 scmd_printk(KERN_ERR, SCpnt, "Unknown command %x\n", rq->cmd_flags);
-                return 0;
+                goto out;
         }
 
         SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt,
@@ -470,7 +487,7 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
                          */
                         scmd_printk(KERN_ERR, SCpnt,
                                     "FUA write on READ/WRITE(6) drive\n");
-                        return 0;
+                        goto out;
                 }
 
                 SCpnt->cmnd[1] |= (unsigned char) ((block >> 16) & 0x1f);
@@ -501,7 +518,9 @@ static int sd_init_command(struct scsi_cmnd * SCpnt)
          * This indicates that the command is ready from our end to be
          * queued.
          */
-        return 1;
+        ret = BLKPREP_OK;
+ out:
+        return scsi_prep_return(q, rq, ret);
 }
 
 /**
@@ -1669,6 +1688,7 @@ static int sd_probe(struct device *dev)
 
         sd_revalidate_disk(gd);
 
+        blk_queue_prep_rq(sdp->request_queue, sd_prep_fn);
         blk_queue_issue_flush_fn(sdp->request_queue, sd_issue_flush);
 
         gd->driverfs_dev = &sdp->sdev_gendev;