Introductory patches for bio refactor.

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
@@ -1518,11 +1518,13 @@ static int ll_merge_requests_fn(struct r
 		/*
 		 * propagate the combined length to the end of the requests
 		 */
+		total_hw_segments--;
+		if (total_hw_segments > q->max_hw_segments)
+			return 0;
 		if (req->nr_hw_segments == 1)
 			req->bio->bi_hw_front_size = len;
 		if (next->nr_hw_segments == 1)
 			next->biotail->bi_hw_back_size = len;
-		total_hw_segments--;
 	}
 
 	if (total_hw_segments > q->max_hw_segments)

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
@@ -2907,8 +2907,8 @@ 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;

@@ -2977,7 +2977,7 @@ 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;

@@ -3373,7 +3373,7 @@ 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);
 		}
 
 		/*

@@ -3678,14 +3678,22 @@ 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
@@ -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
@@ -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
@@ -1426,7 +1426,7 @@ 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
@@ -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/drivers/message/fusion/mptsas.c ./drivers/message/fusion/mptsas.c
@@ -1382,7 +1382,7 @@ static int mptsas_smp_handler(struct Scs
 		       mpt_addr_size()) << MPI_SGE_FLAGS_SHIFT;
 	flagsLength |= (req->data_len - 4);
 
-	dma_addr_out = pci_map_single(ioc->pcidev, bio_data(req->bio),
+	dma_addr_out = pci_map_single(ioc->pcidev, blk_rq_data(req),
 				      req->data_len, PCI_DMA_BIDIRECTIONAL);
 	if (!dma_addr_out)
 		goto put_mf;

@@ -1392,7 +1392,7 @@ static int mptsas_smp_handler(struct Scs
 	/* response */
 	flagsLength = MPT_SGE_FLAGS_SSIMPLE_READ;
 	flagsLength |= rsp->data_len + 4;
-	dma_addr_in =  pci_map_single(ioc->pcidev, bio_data(rsp->bio),
+	dma_addr_in =  pci_map_single(ioc->pcidev, blk_rq_data(rsp),
 				      rsp->data_len, PCI_DMA_BIDIRECTIONAL);
 	if (!dma_addr_in)
 		goto unmap;

diff .prev/drivers/scsi/libsas/sas_expander.c ./drivers/scsi/libsas/sas_expander.c
@@ -1924,8 +1924,8 @@ int sas_smp_handler(struct Scsi_Host *sh
 		return -EINVAL;
 	}
 
-	ret = smp_execute_task(dev, bio_data(req->bio), req->data_len,
-			       bio_data(rsp->bio), rsp->data_len);
+	ret = smp_execute_task(dev, blk_rq_data(req), req->data_len,
+			       blk_rq_data(rsp), rsp->data_len);
 
 	return ret;
 }

diff .prev/include/linux/bio.h ./include/linux/bio.h
@@ -167,8 +167,7 @@ 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)

@@ -177,7 +176,6 @@ 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
@@ -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)
 {

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
@@ -2904,10 +2904,11 @@ static void init_request_from_bio(struct
 	req->errors = 0;
 	req->hard_sector = req->sector = bio->bi_sector;
 	req->hard_nr_sectors = req->nr_sectors = bio_sectors(bio);
-	req->current_nr_sectors = req->hard_cur_sectors = bio_cur_sectors(bio);
+	req->bio = req->biotail = bio;
+	req->current_nr_sectors = req->hard_cur_sectors =
+		blk_rq_cur_sectors(req);
 	req->nr_phys_segments = bio_phys_segments(req->q, bio);
 	req->nr_hw_segments = bio_hw_segments(req->q, bio);
-	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;

@@ -2978,7 +2979,7 @@ static int __make_request(struct request
 			 * not touch req->buffer either...
 			 */
 			req->buffer = blk_rq_data(req);
-			req->current_nr_sectors = bio_cur_sectors(bio);
+			req->current_nr_sectors = blk_rq_cur_sectors(req);
 			req->hard_cur_sectors = req->current_nr_sectors;
 			req->sector = req->hard_sector = bio->bi_sector;
 			req->nr_sectors = req->hard_nr_sectors += nr_sectors;

@@ -3371,7 +3372,7 @@ static void blk_recalc_rq_sectors(struct
 		    (rq->sector <= rq->hard_sector)) {
 			rq->sector = rq->hard_sector;
 			rq->nr_sectors = rq->hard_nr_sectors;
-			rq->hard_cur_sectors = bio_cur_sectors(rq->bio);
+			rq->hard_cur_sectors = blk_rq_cur_sectors(rq);
 			rq->current_nr_sectors = rq->hard_cur_sectors;
 			rq->buffer = blk_rq_data(rq);
 		}

@@ -3675,13 +3676,13 @@ void blk_rq_bio_prep(struct request_queu
 
 	rq->nr_phys_segments = bio_phys_segments(q, bio);
 	rq->nr_hw_segments = bio_hw_segments(q, bio);
-	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->data_len = bio->bi_size;
 
 	rq->bio = rq->biotail = bio;
 	rq->buffer = blk_rq_data(rq);
+	rq->current_nr_sectors = blk_rq_cur_sectors(rq);
+	rq->hard_cur_sectors = rq->current_nr_sectors;
 }
 
 EXPORT_SYMBOL(blk_rq_bio_prep);

@@ -3693,6 +3694,11 @@ void *blk_rq_data(struct request *rq)
 }
 EXPORT_SYMBOL(blk_rq_data);
 
+int blk_rq_cur_bytes(struct request *rq)
+{
+	return bio_iovec(rq->bio)->bv_len;
+}
+EXPORT_SYMBOL(blk_rq_cur_bytes);
 
 int kblockd_schedule_work(struct work_struct *work)
 {

diff .prev/drivers/ide/ide-cd.c ./drivers/ide/ide-cd.c
@@ -1173,7 +1173,8 @@ static ide_startstop_t cdrom_read_intr (
 
 	/* First, figure out if we need to bit-bucket
 	   any of the leading sectors. */
-	nskip = min_t(int, rq->current_nr_sectors - bio_cur_sectors(rq->bio), sectors_to_transfer);
+	nskip = min_t(int, rq->current_nr_sectors - blk_rq_cur_sectors(rq),
+		      sectors_to_transfer);
 
 	while (nskip > 0) {
 		/* We need to throw away a sector. */

@@ -1273,7 +1274,7 @@ static int cdrom_read_from_buffer (ide_d
 	   represent the number of sectors to skip at the start of a transfer
 	   will fail.  I think that this will never happen, but let's be
 	   paranoid and check. */
-	if (rq->current_nr_sectors < bio_cur_sectors(rq->bio) &&
+	if (rq->current_nr_sectors < blk_rq_cur_sectors(rq) &&
 	    (rq->sector & (sectors_per_frame - 1))) {
 		printk(KERN_ERR "%s: cdrom_read_from_buffer: buffer botch (%ld)\n",
 			drive->name, (long)rq->sector);

@@ -1308,7 +1309,7 @@ static ide_startstop_t cdrom_start_read_
 	nskip = rq->sector & (sectors_per_frame - 1);
 	if (nskip > 0) {
 		/* Sanity check... */
-		if (rq->current_nr_sectors != bio_cur_sectors(rq->bio) &&
+		if (rq->current_nr_sectors != blk_rq_cur_sectors(rq) &&
 			(rq->sector & (sectors_per_frame - 1))) {
 			printk(KERN_ERR "%s: cdrom_start_read_continuation: buffer botch (%u)\n",
 				drive->name, rq->current_nr_sectors);

@@ -1389,7 +1390,7 @@ static void restore_request (struct requ
 		rq->nr_sectors += n;
 		rq->sector -= n;
 	}
-	rq->hard_cur_sectors = rq->current_nr_sectors = bio_cur_sectors(rq->bio);
+	rq->hard_cur_sectors = rq->current_nr_sectors = blk_rq_cur_sectors(rq);
 	rq->hard_nr_sectors = rq->nr_sectors;
 	rq->hard_sector = rq->sector;
 	rq->q->prep_rq_fn(rq->q, rq);

@@ -1770,7 +1771,7 @@ static ide_startstop_t cdrom_newpc_intr(
 		 */
 		if (rq->bio) {
 			ptr = blk_rq_data(rq);
-			blen = bio_iovec(rq->bio)->bv_len;
+			blen = blk_rq_cur_bytes(rq);
 		}
 
 		if (!ptr) {

diff .prev/drivers/ide/ide-io.c ./drivers/ide/ide-io.c
@@ -1424,7 +1424,7 @@ static ide_startstop_t ide_dma_timeout_r
 		goto out;
 
 	rq->sector = rq->bio->bi_sector;
-	rq->current_nr_sectors = bio_iovec(rq->bio)->bv_len >> 9;
+	rq->current_nr_sectors = blk_rq_cur_sectors(rq);
 	rq->hard_cur_sectors = rq->current_nr_sectors;
 	rq->buffer = blk_rq_data(rq);
 out:

diff .prev/include/linux/bio.h ./include/linux/bio.h
@@ -175,7 +175,6 @@ struct bio {
 #define bio_offset(bio)		bio_iovec((bio))->bv_offset
 #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_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
@@ -701,6 +701,11 @@ extern void blk_execute_rq_nowait(struct
 				  struct request *, int, rq_end_io_fn *);
 extern int blk_verify_command(unsigned char *, int);
 extern void *blk_rq_data(struct request *);
+extern int blk_rq_cur_bytes(struct request *);
+static inline int blk_rq_cur_sectors(struct request *rq)
+{
+	return blk_rq_cur_bytes(rq) >> 9;
+}
 
 static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
 {

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
@@ -1313,9 +1313,11 @@ static int blk_hw_contig_segment(struct 
 int blk_rq_map_sg(struct request_queue *q, struct request *rq,
 		  struct scatterlist *sg)
 {
-	struct bio_vec *bvec, *bvprv;
-	struct bio *bio;
-	int nsegs, i, cluster;
+	struct bio_vec bvec;
+	struct bio_vec bvprv = { 0 };
+	struct req_iterator i;
+	int nsegs;
+	int cluster;
 
 	nsegs = 0;
 	cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);

@@ -1323,36 +1325,30 @@ int blk_rq_map_sg(struct request_queue *
 	/*
 	 * for each bio in rq
 	 */
-	bvprv = NULL;
-	rq_for_each_bio(bio, rq) {
-		/*
-		 * for each segment in bio
-		 */
-		bio_for_each_segment(bvec, bio, i) {
-			int nbytes = bvec->bv_len;
+	rq_for_each_segment(rq, i, bvec) {
+		int nbytes = bvec.bv_len;
 
-			if (bvprv && cluster) {
-				if (sg[nsegs - 1].length + nbytes > q->max_segment_size)
-					goto new_segment;
-
-				if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
-					goto new_segment;
-				if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
-					goto new_segment;
+		if (bvprv.bv_page && cluster) {
+			if (sg[nsegs - 1].length + nbytes > q->max_segment_size)
+				goto new_segment;
+
+			if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bvec))
+				goto new_segment;
+			if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bvec))
+				goto new_segment;
 
-				sg[nsegs - 1].length += nbytes;
-			} else {
+			sg[nsegs - 1].length += nbytes;
+		} else {
 new_segment:
-				memset(&sg[nsegs],0,sizeof(struct scatterlist));
-				sg[nsegs].page = bvec->bv_page;
-				sg[nsegs].length = nbytes;
-				sg[nsegs].offset = bvec->bv_offset;
+			memset(&sg[nsegs], 0, sizeof(struct scatterlist));
+			sg[nsegs].page = bvec.bv_page;
+			sg[nsegs].length = nbytes;
+			sg[nsegs].offset = bvec.bv_offset;
 
-				nsegs++;
-			}
-			bvprv = bvec;
-		} /* segments in bio */
-	} /* bios in rq */
+			nsegs++;
+		}
+		bvprv = bvec;
+	}
 
 	return nsegs;
 }

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diff .prev/drivers/block/lguest_blk.c ./drivers/block/lguest_blk.c
@@ -142,25 +142,24 @@ static irqreturn_t lgb_irq(int irq, void
  * return the total length. */
 static unsigned int req_to_dma(struct request *req, struct lguest_dma *dma)
 {
-	unsigned int i = 0, idx, len = 0;
-	struct bio *bio;
+	unsigned int i = 0;
+	unsigned int len = 0;
+	struct req_iterator idx;
+	struct bio_vec bvec;
 
-	rq_for_each_bio(bio, req) {
-		struct bio_vec *bvec;
-		bio_for_each_segment(bvec, bio, idx) {
+	rq_for_each_segment(req, idx, bvec) {
 			/* We told the block layer not to give us too many. */
-			BUG_ON(i == LGUEST_MAX_DMA_SECTIONS);
+		BUG_ON(i == LGUEST_MAX_DMA_SECTIONS);
 			/* If we had a zero-length segment, it would look like
 			 * the end of the data referred to by the "struct
 			 * lguest_dma", so make sure that doesn't happen. */
-			BUG_ON(!bvec->bv_len);
+		BUG_ON(!bvec.bv_len);
 			/* Convert page & offset to a physical address */
-			dma->addr[i] = page_to_phys(bvec->bv_page)
-				+ bvec->bv_offset;
-			dma->len[i] = bvec->bv_len;
-			len += bvec->bv_len;
-			i++;
-		}
+		dma->addr[i] = page_to_phys(bvec.bv_page)
+			+ bvec.bv_offset;
+		dma->len[i] = bvec.bv_len;
+		len += bvec.bv_len;
+		i++;
 	}
 	/* If the array isn't full, we mark the end with a 0 length */
 	if (i < LGUEST_MAX_DMA_SECTIONS)

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diff .prev/drivers/s390/block/dasd_diag.c ./drivers/s390/block/dasd_diag.c
@@ -471,14 +471,13 @@ dasd_diag_build_cp(struct dasd_device * 
 	struct dasd_ccw_req *cqr;
 	struct dasd_diag_req *dreq;
 	struct dasd_diag_bio *dbio;
-	struct bio *bio;
-	struct bio_vec *bv;
+	struct bio_vec bv;
 	char *dst;
 	unsigned int count, datasize;
 	sector_t recid, first_rec, last_rec;
 	unsigned int blksize, off;
 	unsigned char rw_cmd;
-	int i;
+	struct req_iterator i;
 
 	if (rq_data_dir(req) == READ)
 		rw_cmd = MDSK_READ_REQ;

@@ -492,13 +491,11 @@ dasd_diag_build_cp(struct dasd_device * 
 	last_rec = (req->sector + req->nr_sectors - 1) >> device->s2b_shift;
 	/* Check struct bio and count the number of blocks for the request. */
 	count = 0;
-	rq_for_each_bio(bio, req) {
-		bio_for_each_segment(bv, bio, i) {
-			if (bv->bv_len & (blksize - 1))
-				/* Fba can only do full blocks. */
-				return ERR_PTR(-EINVAL);
-			count += bv->bv_len >> (device->s2b_shift + 9);
-		}
+	rq_for_each_segment(req, i, bv) {
+		if (bv.bv_len & (blksize - 1))
+			/* Fba can only do full blocks. */
+			return ERR_PTR(-EINVAL);
+		count += bv.bv_len >> (device->s2b_shift + 9);
 	}
 	/* Paranoia. */
 	if (count != last_rec - first_rec + 1)

@@ -515,20 +512,19 @@ dasd_diag_build_cp(struct dasd_device * 
 	dreq->block_count = count;
 	dbio = dreq->bio;
 	recid = first_rec;
-	rq_for_each_bio(bio, req) {
-		bio_for_each_segment(bv, bio, i) {
-			dst = page_address(bv->bv_page) + bv->bv_offset;
-			for (off = 0; off < bv->bv_len; off += blksize) {
-				memset(dbio, 0, sizeof (struct dasd_diag_bio));
-				dbio->type = rw_cmd;
-				dbio->block_number = recid + 1;
-				dbio->buffer = dst;
-				dbio++;
-				dst += blksize;
-				recid++;
-			}
+	rq_for_each_segment(req, i, bv) {
+		dst = page_address(bv.bv_page) + bv.bv_offset;
+		for (off = 0; off < bv.bv_len; off += blksize) {
+			memset(dbio, 0, sizeof(struct dasd_diag_bio));
+			dbio->type = rw_cmd;
+			dbio->block_number = recid + 1;
+			dbio->buffer = dst;
+			dbio++;
+			dst += blksize;
+			recid++;
 		}
 	}
+
 	cqr->retries = DIAG_MAX_RETRIES;
 	cqr->buildclk = get_clock();
 	if (req->cmd_flags & REQ_FAILFAST)

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diff .prev/drivers/s390/char/tape_34xx.c ./drivers/s390/char/tape_34xx.c
@@ -1134,21 +1134,18 @@ tape_34xx_bread(struct tape_device *devi
 {
 	struct tape_request *request;
 	struct ccw1 *ccw;
-	int count = 0, i;
+	int count = 0;
+	struct req_iterator i;
 	unsigned off;
 	char *dst;
-	struct bio_vec *bv;
-	struct bio *bio;
+	struct bio_vec bv;
 	struct tape_34xx_block_id *	start_block;
 
 	DBF_EVENT(6, "xBREDid:");
 
 	/* Count the number of blocks for the request. */
-	rq_for_each_bio(bio, req) {
-		bio_for_each_segment(bv, bio, i) {
+	rq_for_each_segment(req, i, bv)
 			count += bv->bv_len >> (TAPEBLOCK_HSEC_S2B + 9);
-		}
-	}
 
 	/* Allocate the ccw request. */
 	request = tape_alloc_request(3+count+1, 8);

@@ -1175,18 +1172,16 @@ tape_34xx_bread(struct tape_device *devi
 	ccw = tape_ccw_cc(ccw, NOP, 0, NULL);
 	ccw = tape_ccw_cc(ccw, NOP, 0, NULL);
 
-	rq_for_each_bio(bio, req) {
-		bio_for_each_segment(bv, bio, i) {
-			dst = kmap(bv->bv_page) + bv->bv_offset;
-			for (off = 0; off < bv->bv_len;
-			     off += TAPEBLOCK_HSEC_SIZE) {
-				ccw->flags = CCW_FLAG_CC;
-				ccw->cmd_code = READ_FORWARD;
-				ccw->count = TAPEBLOCK_HSEC_SIZE;
-				set_normalized_cda(ccw, (void*) __pa(dst));
-				ccw++;
-				dst += TAPEBLOCK_HSEC_SIZE;
-			}
+	rq_for_each_segment(req, i, bv) {
+		dst = kmap(bv.bv_page) + bv.bv_offset;
+		for (off = 0; off < bv.bv_len;
+		     off += TAPEBLOCK_HSEC_SIZE) {
+			ccw->flags = CCW_FLAG_CC;
+			ccw->cmd_code = READ_FORWARD;
+			ccw->count = TAPEBLOCK_HSEC_SIZE;
+			set_normalized_cda(ccw, (void *) __pa(dst));
+			ccw++;
+			dst += TAPEBLOCK_HSEC_SIZE;
 		}
 	}
 

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diff .prev/include/linux/blkdev.h ./include/linux/blkdev.h
@@ -637,6 +637,24 @@ static inline void blk_queue_bounce(stru
 }
 #endif /* CONFIG_MMU */
 
+struct req_iterator {
+	int i;
+	struct bio *bio;
+};
+
+#define _bio_for_each_segment(bvec, bio, i)		\
+	for (i = (bio)->bi_idx;				\
+	     i < (bio)->bi_vcnt;			\
+	     i++) if ((bvec = *bio_iovec_idx(bio, i)), 1)
+
+#define rq_for_each_segment(rq, _iter, bvec)	\
+	for (_iter.bio = (rq)->bio;		\
+	     _iter.bio;				\
+	     _iter.bio = _iter.bio->bi_next)	\
+		_bio_for_each_segment(bvec, _iter.bio, _iter.i)
+
+#define rq_iter_last(rq, _iter) (_iter.bio->bi_next == NULL && 	\
+				 _iter.i == _iter.bio->bi_vcnt - 1)
 #define rq_for_each_bio(_bio, rq)	\
 	if ((rq->bio))			\
 		for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
@@ -42,6 +42,7 @@ static void drive_stat_acct(struct reque
 static void init_request_from_bio(struct request *req, struct bio *bio);
 static int __make_request(struct request_queue *q, struct bio *bio);
 static struct io_context *current_io_context(gfp_t gfp_flags, int node);
+static void blk_recalc_rq_segments(struct request *rq);
 
 /*
  * For the allocated request tables

@@ -1209,65 +1210,91 @@ EXPORT_SYMBOL(blk_dump_rq_flags);
 
 void blk_recount_segments(struct request_queue *q, struct bio *bio)
 {
-	struct bio_vec *bv, *bvprv = NULL;
-	int i, nr_phys_segs, nr_hw_segs, seg_size, hw_seg_size, cluster;
+	struct request rq;
+	struct bio *nxt = bio->bi_next;
+	rq.q = q;
+	rq.bio = rq.biotail = bio;
+	bio->bi_next = NULL;
+	blk_recalc_rq_segments(&rq);
+	bio->bi_next = nxt;
+	bio->bi_phys_segments = rq.nr_phys_segments;
+	bio->bi_hw_segments = rq.nr_hw_segments;
+	bio->bi_flags |= (1 << BIO_SEG_VALID);
+}
+EXPORT_SYMBOL(blk_recount_segments);
+
+static void blk_recalc_rq_segments(struct request *rq)
+{
+	int nr_phys_segs;
+	int nr_hw_segs;
+	unsigned int phys_size;
+	unsigned int hw_size;
+	struct bio_vec bv;
+	struct bio_vec bvprv = {0};
+	int seg_size;
+	int hw_seg_size;
+	int cluster;
+	struct req_iterator i;
 	int high, highprv = 1;
+	struct request_queue *q = rq->q;
 
-	if (unlikely(!bio->bi_io_vec))
+	if (!rq->bio)
 		return;
 
 	cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
-	hw_seg_size = seg_size = nr_phys_segs = nr_hw_segs = 0;
-	bio_for_each_segment(bv, bio, i) {
+	hw_seg_size = seg_size = 0;
+	phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
+	rq_for_each_segment(rq, i, bv) {
 		/*
 		 * the trick here is making sure that a high page is never
 		 * considered part of another segment, since that might
 		 * change with the bounce page.
 		 */
-		high = page_to_pfn(bv->bv_page) > q->bounce_pfn;
+		high = page_to_pfn(bv.bv_page) > q->bounce_pfn;
 		if (high || highprv)
 			goto new_hw_segment;
 		if (cluster) {
-			if (seg_size + bv->bv_len > q->max_segment_size)
+			if (seg_size + bv.bv_len > q->max_segment_size)
 				goto new_segment;
-			if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
+			if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv))
 				goto new_segment;
-			if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
+			if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv))
 				goto new_segment;
-			if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
+			if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv.bv_len))
 				goto new_hw_segment;
 
-			seg_size += bv->bv_len;
-			hw_seg_size += bv->bv_len;
+			seg_size += bv.bv_len;
+			hw_seg_size += bv.bv_len;
 			bvprv = bv;
 			continue;
 		}
 new_segment:
-		if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) &&
-		    !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) {
-			hw_seg_size += bv->bv_len;
-		} else {
+		if (BIOVEC_VIRT_MERGEABLE(&bvprv, &bv) &&
+		    !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv.bv_len))
+			hw_seg_size += bv.bv_len;
+		else {
 new_hw_segment:
-			if (hw_seg_size > bio->bi_hw_front_size)
-				bio->bi_hw_front_size = hw_seg_size;
-			hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len;
+			if (nr_hw_segs == 1 &&
+			    hw_seg_size > rq->bio->bi_hw_front_size)
+				rq->bio->bi_hw_front_size = hw_seg_size;
+			hw_seg_size = BIOVEC_VIRT_START_SIZE(&bv) + bv.bv_len;
 			nr_hw_segs++;
 		}
 
 		nr_phys_segs++;
 		bvprv = bv;
-		seg_size = bv->bv_len;
+		seg_size = bv.bv_len;
 		highprv = high;
 	}
-	if (hw_seg_size > bio->bi_hw_back_size)
-		bio->bi_hw_back_size = hw_seg_size;
-	if (nr_hw_segs == 1 && hw_seg_size > bio->bi_hw_front_size)
-		bio->bi_hw_front_size = hw_seg_size;
-	bio->bi_phys_segments = nr_phys_segs;
-	bio->bi_hw_segments = nr_hw_segs;
-	bio->bi_flags |= (1 << BIO_SEG_VALID);
+
+	if (nr_hw_segs == 1 &&
+	    hw_seg_size > rq->bio->bi_hw_front_size)
+		rq->bio->bi_hw_front_size = hw_seg_size;
+	if (hw_seg_size > rq->biotail->bi_hw_back_size)
+		rq->biotail->bi_hw_back_size = hw_seg_size;
+	rq->nr_phys_segments = nr_phys_segs;
+	rq->nr_hw_segments = nr_hw_segs;
 }
-EXPORT_SYMBOL(blk_recount_segments);
 
 static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
 				   struct bio *nxt)

@@ -3313,48 +3340,6 @@ void submit_bio(int rw, struct bio *bio)
 
 EXPORT_SYMBOL(submit_bio);
 
-static void blk_recalc_rq_segments(struct request *rq)
-{
-	struct bio *bio, *prevbio = NULL;
-	int nr_phys_segs, nr_hw_segs;
-	unsigned int phys_size, hw_size;
-	struct request_queue *q = rq->q;
-
-	if (!rq->bio)
-		return;
-
-	phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
-	rq_for_each_bio(bio, rq) {
-		/* Force bio hw/phys segs to be recalculated. */
-		bio->bi_flags &= ~(1 << BIO_SEG_VALID);
-
-		nr_phys_segs += bio_phys_segments(q, bio);
-		nr_hw_segs += bio_hw_segments(q, bio);
-		if (prevbio) {
-			int pseg = phys_size + prevbio->bi_size + bio->bi_size;
-			int hseg = hw_size + prevbio->bi_size + bio->bi_size;
-
-			if (blk_phys_contig_segment(q, prevbio, bio) &&
-			    pseg <= q->max_segment_size) {
-				nr_phys_segs--;
-				phys_size += prevbio->bi_size + bio->bi_size;
-			} else
-				phys_size = 0;
-
-			if (blk_hw_contig_segment(q, prevbio, bio) &&
-			    hseg <= q->max_segment_size) {
-				nr_hw_segs--;
-				hw_size += prevbio->bi_size + bio->bi_size;
-			} else
-				hw_size = 0;
-		}
-		prevbio = bio;
-	}
-
-	rq->nr_phys_segments = nr_phys_segs;
-	rq->nr_hw_segments = nr_hw_segs;
-}
-
 static void blk_recalc_rq_sectors(struct request *rq, int nsect)
 {
 	if (blk_fs_request(rq)) {

diff .prev/include/linux/blkdev.h ./include/linux/blkdev.h
@@ -655,9 +655,6 @@ struct req_iterator {
 
 #define rq_iter_last(rq, _iter) (_iter.bio->bi_next == NULL && 	\
 				 _iter.i == _iter.bio->bi_vcnt - 1)
-#define rq_for_each_bio(_bio, rq)	\
-	if ((rq->bio))			\
-		for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
 
 extern int blk_register_queue(struct gendisk *disk);
 extern void blk_unregister_queue(struct gendisk *disk);