Introduce rq_for_each_segment replacing rq_for_each_bio

Every usage of rq_for_each_bio wraps a usage of
bio_for_each_segment, so these can be combined into
rq_for_each_segment.

We define "struct req_iterator" to hold the 'bio' and 'index' that
are needed for the double iteration.

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

Various compile fixes by me...

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

5 files changed, 69 insertions, 82 deletions

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 085b7794fb3..f0a86e201b4 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -2437,22 +2437,19 @@ static void rw_interrupt(void)
 /* Compute maximal contiguous buffer size. */
 static int buffer_chain_size(void)
 {
-	struct bio *bio;
 	struct bio_vec *bv;
-	int size, i;
+	int size;
+	struct req_iterator iter;
 	char *base;
 
 	base = bio_data(current_req->bio);
 	size = 0;
 
-	rq_for_each_bio(bio, current_req) {
-		bio_for_each_segment(bv, bio, i) {
-			if (page_address(bv->bv_page) + bv->bv_offset !=
-			    base + size)
-				break;
+	rq_for_each_segment(bv, current_req, iter) {
+		if (page_address(bv->bv_page) + bv->bv_offset != base + size)
+			break;
 
-			size += bv->bv_len;
-		}
+		size += bv->bv_len;
 	}
 
 	return size >> 9;
@@ -2479,9 +2476,9 @@ static void copy_buffer(int ssize, int max_sector, int max_sector_2)
 {
 	int remaining;		/* number of transferred 512-byte sectors */
 	struct bio_vec *bv;
-	struct bio *bio;
 	char *buffer, *dma_buffer;
-	int size, i;
+	int size;
+	struct req_iterator iter;
 
 	max_sector = transfer_size(ssize,
 				   min(max_sector, max_sector_2),
@@ -2514,43 +2511,41 @@ static void copy_buffer(int ssize, int max_sector, int max_sector_2)
 
 	size = current_req->current_nr_sectors << 9;
 
-	rq_for_each_bio(bio, current_req) {
-		bio_for_each_segment(bv, bio, i) {
-			if (!remaining)
-				break;
+	rq_for_each_segment(bv, current_req, iter) {
+		if (!remaining)
+			break;
 
-			size = bv->bv_len;
-			SUPBOUND(size, remaining);
+		size = bv->bv_len;
+		SUPBOUND(size, remaining);
 
-			buffer = page_address(bv->bv_page) + bv->bv_offset;
+		buffer = page_address(bv->bv_page) + bv->bv_offset;
 #ifdef FLOPPY_SANITY_CHECK
-			if (dma_buffer + size >
-			    floppy_track_buffer + (max_buffer_sectors << 10) ||
-			    dma_buffer < floppy_track_buffer) {
-				DPRINT("buffer overrun in copy buffer %d\n",
-				       (int)((floppy_track_buffer -
-					      dma_buffer) >> 9));
-				printk("fsector_t=%d buffer_min=%d\n",
-				       fsector_t, buffer_min);
-				printk("current_count_sectors=%ld\n",
-				       current_count_sectors);
-				if (CT(COMMAND) == FD_READ)
-					printk("read\n");
-				if (CT(COMMAND) == FD_WRITE)
-					printk("write\n");
-				break;
-			}
-			if (((unsigned long)buffer) % 512)
-				DPRINT("%p buffer not aligned\n", buffer);
-#endif
+		if (dma_buffer + size >
+		    floppy_track_buffer + (max_buffer_sectors << 10) ||
+		    dma_buffer < floppy_track_buffer) {
+			DPRINT("buffer overrun in copy buffer %d\n",
+			       (int)((floppy_track_buffer -
+				      dma_buffer) >> 9));
+			printk("fsector_t=%d buffer_min=%d\n",
+			       fsector_t, buffer_min);
+			printk("current_count_sectors=%ld\n",
+			       current_count_sectors);
 			if (CT(COMMAND) == FD_READ)
-				memcpy(buffer, dma_buffer, size);
-			else
-				memcpy(dma_buffer, buffer, size);
-
-			remaining -= size;
-			dma_buffer += size;
+				printk("read\n");
+			if (CT(COMMAND) == FD_WRITE)
+				printk("write\n");
+			break;
 		}
+		if (((unsigned long)buffer) % 512)
+			DPRINT("%p buffer not aligned\n", buffer);
+#endif
+		if (CT(COMMAND) == FD_READ)
+			memcpy(buffer, dma_buffer, size);
+		else
+			memcpy(dma_buffer, buffer, size);
+
+		remaining -= size;
+		dma_buffer += size;
 	}
 #ifdef FLOPPY_SANITY_CHECK
 	if (remaining) {
diff --git a/drivers/block/lguest_blk.c b/drivers/block/lguest_blk.c
index 160cf14431a..1e838ae60a6 100644
--- a/drivers/block/lguest_blk.c
+++ b/drivers/block/lguest_blk.c
@@ -142,12 +142,11 @@ static irqreturn_t lgb_irq(int irq, void *_bd)
  * 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, len = 0;
+	struct req_iterator iter;
+	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(bvec, req, iter) {
 			/* We told the block layer not to give us too many. */
 			BUG_ON(i == LGUEST_MAX_DMA_SECTIONS);
 			/* If we had a zero-length segment, it would look like
@@ -160,7 +159,6 @@ static unsigned int req_to_dma(struct request *req, struct lguest_dma *dma)
 			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)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index be92c658f06..228b2ff577a 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -180,7 +180,7 @@ static inline int sock_send_bvec(struct socket *sock, struct bio_vec *bvec,
 
 static int nbd_send_req(struct nbd_device *lo, struct request *req)
 {
-	int result, i, flags;
+	int result, flags;
 	struct nbd_request request;
 	unsigned long size = req->nr_sectors << 9;
 	struct socket *sock = lo->sock;
@@ -205,16 +205,15 @@ static int nbd_send_req(struct nbd_device *lo, struct request *req)
 	}
 
 	if (nbd_cmd(req) == NBD_CMD_WRITE) {
-		struct bio *bio;
+		struct req_iterator iter;
+		struct bio_vec *bvec;
 		/*
 		 * we are really probing at internals to determine
 		 * whether to set MSG_MORE or not...
 		 */
-		rq_for_each_bio(bio, req) {
-			struct bio_vec *bvec;
-			bio_for_each_segment(bvec, bio, i) {
+		rq_for_each_segment(bvec, req, iter) {
 				flags = 0;
-				if ((i < (bio->bi_vcnt - 1)) || bio->bi_next)
+				if (!rq_iter_last(req, iter))
 					flags = MSG_MORE;
 				dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
 						lo->disk->disk_name, req,
@@ -226,7 +225,6 @@ static int nbd_send_req(struct nbd_device *lo, struct request *req)
 							result);
 					goto error_out;
 				}
-			}
 		}
 	}
 	return 0;
@@ -321,11 +319,10 @@ static struct request *nbd_read_stat(struct nbd_device *lo)
 	dprintk(DBG_RX, "%s: request %p: got reply\n",
 			lo->disk->disk_name, req);
 	if (nbd_cmd(req) == NBD_CMD_READ) {
-		int i;
-		struct bio *bio;
-		rq_for_each_bio(bio, req) {
-			struct bio_vec *bvec;
-			bio_for_each_segment(bvec, bio, i) {
+		struct req_iterator iter;
+		struct bio_vec *bvec;
+
+		rq_for_each_segment(bvec, req, iter) {
 				result = sock_recv_bvec(sock, bvec);
 				if (result <= 0) {
 					printk(KERN_ERR "%s: Receive data failed (result %d)\n",
@@ -336,7 +333,6 @@ static struct request *nbd_read_stat(struct nbd_device *lo)
 				}
 				dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
 					lo->disk->disk_name, req, bvec->bv_len);
-			}
 		}
 	}
 	return req;
diff --git a/drivers/block/ps3disk.c b/drivers/block/ps3disk.c
index aa8b890c80d..8953e7ce001 100644
--- a/drivers/block/ps3disk.c
+++ b/drivers/block/ps3disk.c
@@ -91,30 +91,30 @@ static void ps3disk_scatter_gather(struct ps3_storage_device *dev,
 				   struct request *req, int gather)
 {
 	unsigned int offset = 0;
-	struct bio *bio;
-	sector_t sector;
+	struct req_iterator iter;
 	struct bio_vec *bvec;
-	unsigned int i = 0, j;
+	unsigned int i = 0;
 	size_t size;
 	void *buf;
 
-	rq_for_each_bio(bio, req) {
-		sector = bio->bi_sector;
+	rq_for_each_segment(bvec, req, iter) {
+		unsigned long flags;
 		dev_dbg(&dev->sbd.core,
 			"%s:%u: bio %u: %u segs %u sectors from %lu\n",
-			__func__, __LINE__, i, bio_segments(bio),
-			bio_sectors(bio), sector);
-		bio_for_each_segment(bvec, bio, j) {
+			__func__, __LINE__, i, bio_segments(iter.bio),
+			bio_sectors(iter.bio),
+			(unsigned long)iter.bio->bi_sector);
+
 			size = bvec->bv_len;
-			buf = __bio_kmap_atomic(bio, j, KM_IRQ0);
+			buf = bvec_kmap_irq(bvec, &flags);
 			if (gather)
 				memcpy(dev->bounce_buf+offset, buf, size);
 			else
 				memcpy(buf, dev->bounce_buf+offset, size);
 			offset += size;
-			flush_kernel_dcache_page(bio_iovec_idx(bio, j)->bv_page);
-			__bio_kunmap_atomic(bio, KM_IRQ0);
-		}
+			flush_kernel_dcache_page(bvec->bv_page);
+			bvec_kunmap_irq(bvec, &flags);
+
 		i++;
 	}
 }
@@ -130,12 +130,13 @@ static int ps3disk_submit_request_sg(struct ps3_storage_device *dev,
 
 #ifdef DEBUG
 	unsigned int n = 0;
-	struct bio *bio;
+	struct bio_vec *bv;
+	struct req_iterator iter;
 
-	rq_for_each_bio(bio, req)
+	rq_for_each_segment(bv, req, iter)
 		n++;
 	dev_dbg(&dev->sbd.core,
-		"%s:%u: %s req has %u bios for %lu sectors %lu hard sectors\n",
+		"%s:%u: %s req has %u bvecs for %lu sectors %lu hard sectors\n",
 		__func__, __LINE__, op, n, req->nr_sectors,
 		req->hard_nr_sectors);
 #endif
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 964e51634f2..6af250113c2 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -150,9 +150,8 @@ static int blkif_queue_request(struct request *req)
 	struct blkfront_info *info = req->rq_disk->private_data;
 	unsigned long buffer_mfn;
 	struct blkif_request *ring_req;
-	struct bio *bio;
+	struct req_iterator iter;
 	struct bio_vec *bvec;
-	int idx;
 	unsigned long id;
 	unsigned int fsect, lsect;
 	int ref;
@@ -186,8 +185,7 @@ static int blkif_queue_request(struct request *req)
 		ring_req->operation = BLKIF_OP_WRITE_BARRIER;
 
 	ring_req->nr_segments = 0;
-	rq_for_each_bio (bio, req) {
-		bio_for_each_segment (bvec, bio, idx) {
+	rq_for_each_segment(bvec, req, iter) {
 			BUG_ON(ring_req->nr_segments
 			       == BLKIF_MAX_SEGMENTS_PER_REQUEST);
 			buffer_mfn = pfn_to_mfn(page_to_pfn(bvec->bv_page));
@@ -213,7 +211,6 @@ static int blkif_queue_request(struct request *req)
 					.last_sect  = lsect };
 
 			ring_req->nr_segments++;
-		}
 	}
 
 	info->ring.req_prod_pvt++;