[PATCH] Cleanup blk_rq_map_* interfaces

Change the blk_rq_map_user() and blk_rq_map_kern() interface to require
a previously allocated request to be passed in. This is both more efficient
for multiple iterations of mapping data to the same request, and it is also
a much nicer API.

Signed-off-by: Jens Axboe <axboe@suse.de>

1 files changed, 14 insertions, 9 deletions

diff --git a/drivers/block/scsi_ioctl.c b/drivers/block/scsi_ioctl.c
index 681871ca5d60..93c4ca874be3 100644
--- a/drivers/block/scsi_ioctl.c
+++ b/drivers/block/scsi_ioctl.c
@@ -216,7 +216,7 @@ static int sg_io(struct file *file, request_queue_t *q,
                 struct gendisk *bd_disk, struct sg_io_hdr *hdr)
 {
         unsigned long start_time;
-        int reading, writing;
+        int reading, writing, ret;
         struct request *rq;
         struct bio *bio;
         char sense[SCSI_SENSE_BUFFERSIZE];
@@ -255,14 +255,17 @@ static int sg_io(struct file *file, request_queue_t *q,
                         reading = 1;
                         break;
                 }
+        }
 
-                rq = blk_rq_map_user(q, writing ? WRITE : READ, hdr->dxferp,
-                                     hdr->dxfer_len);
+        rq = blk_get_request(q, writing ? WRITE : READ, GFP_KERNEL);
+        if (!rq)
+                return -ENOMEM;
 
-                if (IS_ERR(rq))
-                        return PTR_ERR(rq);
-        } else
-                rq = blk_get_request(q, READ, __GFP_WAIT);
+        if (reading || writing) {
+                ret = blk_rq_map_user(q, rq, hdr->dxferp, hdr->dxfer_len);
+                if (ret)
+                        goto out;
+        }
 
         /*
          * fill in request structure
@@ -321,11 +324,13 @@ static int sg_io(struct file *file, request_queue_t *q,
         }
 
         if (blk_rq_unmap_user(rq, bio, hdr->dxfer_len))
-                return -EFAULT;
+                ret = -EFAULT;
 
         /* may not have succeeded, but output values written to control
          * structure (struct sg_io_hdr).  */
-        return 0;
+out:
+        blk_put_request(rq);
+        return ret;
 }
 
 #define OMAX_SB_LEN 16          /* For backward compatibility */