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 085b7794fb3e..f0a86e201b44 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 160cf14431ac..1e838ae60a60 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 be92c658f06e..228b2ff577aa 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 aa8b890c80d7..8953e7ce0016 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 964e51634f2d..6af250113c2a 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++;