[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>

4 files changed, 53 insertions, 58 deletions

diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index 1471aca6fa18..42c4f3651cf8 100644
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -2107,21 +2107,19 @@ EXPORT_SYMBOL(blk_insert_request);
  *    original bio must be passed back in to blk_rq_unmap_user() for proper
  *    unmapping.
  */
-struct request *blk_rq_map_user(request_queue_t *q, int rw, void __user *ubuf,
-                                unsigned int len)
+int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf,
+                    unsigned int len)
 {
         unsigned long uaddr;
-        struct request *rq;
         struct bio *bio;
+        int reading;
 
         if (len > (q->max_sectors << 9))
-                return ERR_PTR(-EINVAL);
-        if ((!len && ubuf) || (len && !ubuf))
-                return ERR_PTR(-EINVAL);
+                return -EINVAL;
+        if (!len || !ubuf)
+                return -EINVAL;
 
-        rq = blk_get_request(q, rw, __GFP_WAIT);
-        if (!rq)
-                return ERR_PTR(-ENOMEM);
+        reading = rq_data_dir(rq) == READ;
 
         /*
          * if alignment requirement is satisfied, map in user pages for
@@ -2129,9 +2127,9 @@ struct request *blk_rq_map_user(request_queue_t *q, int rw, void __user *ubuf,
          */
         uaddr = (unsigned long) ubuf;
         if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q)))
-                bio = bio_map_user(q, NULL, uaddr, len, rw == READ);
+                bio = bio_map_user(q, NULL, uaddr, len, reading);
         else
-                bio = bio_copy_user(q, uaddr, len, rw == READ);
+                bio = bio_copy_user(q, uaddr, len, reading);
 
         if (!IS_ERR(bio)) {
                 rq->bio = rq->biotail = bio;
@@ -2139,14 +2137,13 @@ struct request *blk_rq_map_user(request_queue_t *q, int rw, void __user *ubuf,
 
                 rq->buffer = rq->data = NULL;
                 rq->data_len = len;
-                return rq;
+                return 0;
         }
 
         /*
          * bio is the err-ptr
          */
-        blk_put_request(rq);
-        return (struct request *) bio;
+        return PTR_ERR(bio);
 }
 
 EXPORT_SYMBOL(blk_rq_map_user);
@@ -2160,7 +2157,7 @@ EXPORT_SYMBOL(blk_rq_map_user);
  * Description:
  *    Unmap a request previously mapped by blk_rq_map_user().
  */
-int blk_rq_unmap_user(struct request *rq, struct bio *bio, unsigned int ulen)
+int blk_rq_unmap_user(struct bio *bio, unsigned int ulen)
 {
         int ret = 0;
 
@@ -2171,8 +2168,7 @@ int blk_rq_unmap_user(struct request *rq, struct bio *bio, unsigned int ulen)
                         ret = bio_uncopy_user(bio);
         }
 
-        blk_put_request(rq);
-        return ret;
+        return 0;
 }
 
 EXPORT_SYMBOL(blk_rq_unmap_user);
@@ -2184,39 +2180,29 @@ EXPORT_SYMBOL(blk_rq_unmap_user);
  * @kbuf:       the kernel buffer
  * @len:        length of user data
  */
-struct request *blk_rq_map_kern(request_queue_t *q, int rw, void *kbuf,
-                                unsigned int len, unsigned int gfp_mask)
+int blk_rq_map_kern(request_queue_t *q, struct request *rq, void *kbuf,
+                    unsigned int len, unsigned int gfp_mask)
 {
-        struct request *rq;
         struct bio *bio;
 
         if (len > (q->max_sectors << 9))
-                return ERR_PTR(-EINVAL);
-        if ((!len && kbuf) || (len && !kbuf))
-                return ERR_PTR(-EINVAL);
-
-        rq = blk_get_request(q, rw, gfp_mask);
-        if (!rq)
-                return ERR_PTR(-ENOMEM);
+                return -EINVAL;
+        if (!len || !kbuf)
+                return -EINVAL;
 
         bio = bio_map_kern(q, kbuf, len, gfp_mask);
-        if (!IS_ERR(bio)) {
-                if (rw)
-                        bio->bi_rw |= (1 << BIO_RW);
+        if (IS_ERR(bio))
+                return PTR_ERR(bio);
 
-                rq->bio = rq->biotail = bio;
-                blk_rq_bio_prep(q, rq, bio);
+        if (rq_data_dir(rq) == WRITE)
+                bio->bi_rw |= (1 << BIO_RW);
 
-                rq->buffer = rq->data = NULL;
-                rq->data_len = len;
-                return rq;
-        }
+        rq->bio = rq->biotail = bio;
+        blk_rq_bio_prep(q, rq, bio);
 
-        /*
-         * bio is the err-ptr
-         */
-        blk_put_request(rq);
-        return (struct request *) bio;
+        rq->buffer = rq->data = NULL;
+        rq->data_len = len;
+        return 0;
 }
 
 EXPORT_SYMBOL(blk_rq_map_kern);
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 */
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index beaa561f2ed8..6a7d926774a1 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2097,6 +2097,10 @@ static int cdrom_read_cdda_bpc(struct cdrom_device_info *cdi, __u8 __user *ubuf,
         if (!q)
                 return -ENXIO;
 
+        rq = blk_get_request(q, READ, GFP_KERNEL);
+        if (!rq)
+                return -ENOMEM;
+
         cdi->last_sense = 0;
 
         while (nframes) {
@@ -2108,9 +2112,9 @@ static int cdrom_read_cdda_bpc(struct cdrom_device_info *cdi, __u8 __user *ubuf,
 
                 len = nr * CD_FRAMESIZE_RAW;
 
-                rq = blk_rq_map_user(q, READ, ubuf, len);
-                if (IS_ERR(rq))
-                        return PTR_ERR(rq);
+                ret = blk_rq_map_user(q, rq, ubuf, len);
+                if (ret)
+                        break;
 
                 memset(rq->cmd, 0, sizeof(rq->cmd));
                 rq->cmd[0] = GPCMD_READ_CD;
@@ -2138,7 +2142,7 @@ static int cdrom_read_cdda_bpc(struct cdrom_device_info *cdi, __u8 __user *ubuf,
                         cdi->last_sense = s->sense_key;
                 }
 
-                if (blk_rq_unmap_user(rq, bio, len))
+                if (blk_rq_unmap_user(bio, len))
                         ret = -EFAULT;
 
                 if (ret)
@@ -2149,6 +2153,7 @@ static int cdrom_read_cdda_bpc(struct cdrom_device_info *cdi, __u8 __user *ubuf,
                 ubuf += len;
         }
 
+        blk_put_request(rq);
         return ret;
 }
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 67339bc5f6bc..fc0dce078616 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -558,10 +558,9 @@ extern void blk_sync_queue(struct request_queue *q);
 extern void __blk_stop_queue(request_queue_t *q);
 extern void blk_run_queue(request_queue_t *);
 extern void blk_queue_activity_fn(request_queue_t *, activity_fn *, void *);
-extern struct request *blk_rq_map_user(request_queue_t *, int, void __user *, unsigned int);
-extern int blk_rq_unmap_user(struct request *, struct bio *, unsigned int);
-extern struct request *blk_rq_map_kern(request_queue_t *, int, void *,
-                                        unsigned int, unsigned int);
+extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, unsigned int);
+extern int blk_rq_unmap_user(struct bio *, unsigned int);
+extern int blk_rq_map_kern(request_queue_t *, struct request *, void *, unsigned int, unsigned int);
 extern int blk_execute_rq(request_queue_t *, struct gendisk *, struct request *);
 
 static inline request_queue_t *bdev_get_queue(struct block_device *bdev)