[PATCH 001 of 35] Replace bio_data with blk_rq_data

[NeilBrown <neilb@suse.de>]

Almost every call to bio_data is for the first bio
in a request.  A future patch will add some accounting
information to 'struct request' which will need to be
used to find the start of the request in the bio.
So replace bio_data with blk_rq_data which takes a 'struct request *'

The one exception is in dm-emc were using
   page_address(bio->bi_io_vec[0].bv_page);
is appropriate.

Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
 ./block/ll_rw_blk.c      |   16 ++++++++++++----
 ./drivers/block/floppy.c |    2 +-
 ./drivers/ide/ide-cd.c   |   11 ++++++-----
 ./drivers/ide/ide-io.c   |    2 +-
 ./drivers/md/dm-emc.c    |    2 +-
 ./include/linux/bio.h    |    4 +---
 ./include/linux/blkdev.h |    1 +
 7 files changed, 23 insertions(+), 15 deletions(-)

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
--- .prev/block/ll_rw_blk.c	2007-07-31 11:20:23.000000000 +1000
+++ ./block/ll_rw_blk.c	2007-07-31 11:20:42.000000000 +1000
@@ -2905,8 +2905,8 @@ static void init_request_from_bio(struct
 	req->current_nr_sectors = req->hard_cur_sectors = bio_cur_sectors(bio);
 	req->nr_phys_segments = bio_phys_segments(req->q, bio);
 	req->nr_hw_segments = bio_hw_segments(req->q, bio);
-	req->buffer = bio_data(bio);	/* see ->buffer comment above */
 	req->bio = req->biotail = bio;
+	req->buffer = blk_rq_data(req);	/* see ->buffer comment above */
 	req->ioprio = bio_prio(bio);
 	req->rq_disk = bio->bi_bdev->bd_disk;
 	req->start_time = jiffies;
@@ -2975,7 +2975,7 @@ static int __make_request(struct request
 			 * it didn't need a bounce buffer then it better
 			 * not touch req->buffer either...
 			 */
-			req->buffer = bio_data(bio);
+			req->buffer = blk_rq_data(req);
 			req->current_nr_sectors = bio_cur_sectors(bio);
 			req->hard_cur_sectors = req->current_nr_sectors;
 			req->sector = req->hard_sector = bio->bi_sector;
@@ -3371,7 +3371,7 @@ static void blk_recalc_rq_sectors(struct
 			rq->nr_sectors = rq->hard_nr_sectors;
 			rq->hard_cur_sectors = bio_cur_sectors(rq->bio);
 			rq->current_nr_sectors = rq->hard_cur_sectors;
-			rq->buffer = bio_data(rq->bio);
+			rq->buffer = blk_rq_data(rq);
 		}
 
 		/*
@@ -3676,14 +3676,22 @@ void blk_rq_bio_prep(struct request_queu
 	rq->current_nr_sectors = bio_cur_sectors(bio);
 	rq->hard_cur_sectors = rq->current_nr_sectors;
 	rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
-	rq->buffer = bio_data(bio);
 	rq->data_len = bio->bi_size;
 
 	rq->bio = rq->biotail = bio;
+	rq->buffer = blk_rq_data(rq);
 }
 
 EXPORT_SYMBOL(blk_rq_bio_prep);
 
+void *blk_rq_data(struct request *rq)
+{
+	return page_address(bio_page(rq->bio)) +
+		bio_offset(rq->bio);
+}
+EXPORT_SYMBOL(blk_rq_data);
+
+
 int kblockd_schedule_work(struct work_struct *work)
 {
 	return queue_work(kblockd_workqueue, work);

diff .prev/drivers/block/floppy.c ./drivers/block/floppy.c
--- .prev/drivers/block/floppy.c	2007-07-31 11:20:23.000000000 +1000
+++ ./drivers/block/floppy.c	2007-07-31 11:20:42.000000000 +1000
@@ -2456,7 +2456,7 @@ static int buffer_chain_size(void)
 	int i;
 	char *base;
 
-	base = bio_data(current_req->bio);
+	base = blk_rq_data(current_req);
 	size = 0;
 
 	rq_for_each_bio(bio, current_req) {

diff .prev/drivers/ide/ide-cd.c ./drivers/ide/ide-cd.c
--- .prev/drivers/ide/ide-cd.c	2007-07-31 11:20:23.000000000 +1000
+++ ./drivers/ide/ide-cd.c	2007-07-31 11:20:42.000000000 +1000
@@ -1381,10 +1381,11 @@ static ide_startstop_t cdrom_start_seek 
    start it over entirely, or even put it back on the request queue. */
 static void restore_request (struct request *rq)
 {
-	if (rq->buffer != bio_data(rq->bio)) {
-		sector_t n = (rq->buffer - (char *) bio_data(rq->bio)) / SECTOR_SIZE;
+	if (rq->buffer != blk_rq_data(rq)) {
+		sector_t n = (rq->buffer - (char *)blk_rq_data(rq))
+			/ SECTOR_SIZE;
 
-		rq->buffer = bio_data(rq->bio);
+		rq->buffer = blk_rq_data(rq);
 		rq->nr_sectors += n;
 		rq->sector -= n;
 	}
@@ -1659,7 +1660,7 @@ static void post_transform_command(struc
 		return;
 
 	if (req->bio)
-		ibuf = bio_data(req->bio);
+		ibuf = blk_rq_data(req);
 	else
 		ibuf = req->data;
 
@@ -1768,7 +1769,7 @@ static ide_startstop_t cdrom_newpc_intr(
 		 * bio backed?
 		 */
 		if (rq->bio) {
-			ptr = bio_data(rq->bio);
+			ptr = blk_rq_data(rq);
 			blen = bio_iovec(rq->bio)->bv_len;
 		}
 

diff .prev/drivers/ide/ide-io.c ./drivers/ide/ide-io.c
--- .prev/drivers/ide/ide-io.c	2007-07-31 11:20:23.000000000 +1000
+++ ./drivers/ide/ide-io.c	2007-07-31 11:20:42.000000000 +1000
@@ -1418,7 +1418,7 @@ static ide_startstop_t ide_dma_timeout_r
 	rq->sector = rq->bio->bi_sector;
 	rq->current_nr_sectors = bio_iovec(rq->bio)->bv_len >> 9;
 	rq->hard_cur_sectors = rq->current_nr_sectors;
-	rq->buffer = bio_data(rq->bio);
+	rq->buffer = blk_rq_data(rq);
 out:
 	return ret;
 }

diff .prev/drivers/md/dm-emc.c ./drivers/md/dm-emc.c
--- .prev/drivers/md/dm-emc.c	2007-07-31 11:20:23.000000000 +1000
+++ ./drivers/md/dm-emc.c	2007-07-31 11:20:42.000000000 +1000
@@ -167,7 +167,7 @@ static struct request *emc_trespass_get(
 		return NULL;
 	}
 
-	page22 = (unsigned char *)bio_data(bio);
+	page22 = (unsigned char *)page_address(bio->bi_io_vec[0].bv_page);
 	memset(page22, 0, data_size);
 
 	memcpy(page22, h->short_trespass ?

diff .prev/include/linux/bio.h ./include/linux/bio.h
--- .prev/include/linux/bio.h	2007-07-31 11:20:23.000000000 +1000
+++ ./include/linux/bio.h	2007-07-31 11:20:42.000000000 +1000
@@ -165,8 +165,7 @@ struct bio {
 } while (0)
 
 /*
- * various member access, note that bio_data should of course not be used
- * on highmem page vectors
+ * various member access
  */
 #define bio_iovec_idx(bio, idx)	(&((bio)->bi_io_vec[(idx)]))
 #define bio_iovec(bio)		bio_iovec_idx((bio), (bio)->bi_idx)
@@ -175,7 +174,6 @@ struct bio {
 #define bio_segments(bio)	((bio)->bi_vcnt - (bio)->bi_idx)
 #define bio_sectors(bio)	((bio)->bi_size >> 9)
 #define bio_cur_sectors(bio)	(bio_iovec(bio)->bv_len >> 9)
-#define bio_data(bio)		(page_address(bio_page((bio))) + bio_offset((bio)))
 #define bio_barrier(bio)	((bio)->bi_rw & (1 << BIO_RW_BARRIER))
 #define bio_sync(bio)		((bio)->bi_rw & (1 << BIO_RW_SYNC))
 #define bio_failfast(bio)	((bio)->bi_rw & (1 << BIO_RW_FAILFAST))

diff .prev/include/linux/blkdev.h ./include/linux/blkdev.h
--- .prev/include/linux/blkdev.h	2007-07-31 11:20:23.000000000 +1000
+++ ./include/linux/blkdev.h	2007-07-31 11:20:42.000000000 +1000
@@ -700,6 +700,7 @@ extern int blk_execute_rq(struct request
 extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
 				  struct request *, int, rq_end_io_fn *);
 extern int blk_verify_command(unsigned char *, int);
+extern void *blk_rq_data(struct request *);
 
 static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
 {