# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1244108814 -3600
# Node ID 444a9ed5dfdefb1b7d4a765b7a110e1e74116540
# Parent  2fd85e9a1e21854264c3d3d593749db42b6fc03f
blktap2: use blk_rq_map_sg() here too

Just like in blkfront, not doing so can cause the maximum number of
segments check to trigger.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

linux-2.6-pvops:
 * Rebase against git-fbbc8527 (wean off of use of the BlkBack pageflag)
 * Scatterlist: fix access macro usage, add initcall to device creation.

Signed-off-by: Daniel Stodden <daniel.stodden@xxxxxxxxxx>

diff -r 2fd85e9a1e21 -r 444a9ed5dfde drivers/xen/blktap/blktap.h
--- a/drivers/xen/blktap/blktap.h	Thu Jun 04 10:33:52 2009 +0100
+++ b/drivers/xen/blktap/blktap.h	Thu Jun 04 10:46:54 2009 +0100
@@ -4,6 +4,7 @@
 #include <linux/mm.h>
 #include <linux/fs.h>
 #include <linux/cdev.h>
+#include <linux/scatterlist.h>
 #include <xen/blkif.h>
 #include <xen/grant_table.h>
 
@@ -173,6 +174,7 @@
 
 	int                            pending_cnt;
 	struct blktap_request         *pending_requests[MAX_PENDING_REQS];
+	struct scatterlist             sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 
 	wait_queue_head_t              wq;
 	struct list_head               deferred_queue;
diff -r 2fd85e9a1e21 -r 444a9ed5dfde drivers/xen/blktap/control.c
--- a/drivers/xen/blktap/control.c	Thu Jun 04 10:33:52 2009 +0100
+++ b/drivers/xen/blktap/control.c	Thu Jun 04 10:46:54 2009 +0100
@@ -23,6 +23,7 @@
 	init_rwsem(&tap->tap_sem);
 	init_waitqueue_head(&tap->wq);
 	atomic_set(&tap->refcnt, 0);
+	sg_init_table(tap->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
 
 	tap->minor = minor;
 }
diff -r 2fd85e9a1e21 -r 444a9ed5dfde drivers/xen/blktap/device.c
--- a/drivers/xen/blktap/device.c	Thu Jun 04 10:33:52 2009 +0100
+++ b/drivers/xen/blktap/device.c	Thu Jun 04 10:46:54 2009 +0100
@@ -579,10 +579,9 @@
 			      struct request *req)
 {
 	struct page *page;
-	struct bio_vec *bvec;
-	int usr_idx, err;
-	struct req_iterator iter;
+	int i, usr_idx, err;
 	struct blktap_ring *ring;
+	struct scatterlist *sg;
 	struct blktap_grant_table table;
 	unsigned int fsect, lsect, nr_sects;
 	unsigned long offset, uvaddr, kvaddr;
@@ -609,42 +608,39 @@
 
 	nr_sects = 0;
 	request->nr_pages = 0;
-	blkif_req.nr_segments = 0;
-	rq_for_each_segment(bvec, req, iter) {
-			BUG_ON(blkif_req.nr_segments ==
-			       BLKIF_MAX_SEGMENTS_PER_REQUEST);
+	blkif_req.nr_segments = blk_rq_map_sg(req->q, req, tap->sg);
+	BUG_ON(blkif_req.nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
+	for (i = 0; i < blkif_req.nr_segments; ++i) {
+			sg = tap->sg + i;
+			fsect = sg->offset >> 9;
+			lsect = fsect + (sg->length >> 9) - 1;
+			nr_sects += sg->length >> 9;
 
-			fsect     = bvec->bv_offset >> 9;
-			lsect     = fsect + (bvec->bv_len >> 9) - 1;
-			nr_sects += bvec->bv_len >> 9;
-
-			blkif_req.seg[blkif_req.nr_segments] =
+			blkif_req.seg[i] =
 				(struct blkif_request_segment) {
 				.gref       = 0,
 				.first_sect = fsect,
 				.last_sect  = lsect };
 
-			if (blkback_pagemap_contains_page(bvec->bv_page)) {
+			if (blkback_pagemap_contains_page(sg_page(sg))) {
 				/* foreign page -- use xen */
 				if (blktap_prep_foreign(tap,
 							request,
 							&blkif_req,
-							blkif_req.nr_segments,
-							bvec->bv_page,
+							i,
+							sg_page(sg),
 							&table))
 					goto out;
 			} else {
 				/* do it the old fashioned way */
 				blktap_map(tap,
 					   request,
-					   blkif_req.nr_segments,
-					   bvec->bv_page);
+					   i,
+					   sg_page(sg));
 			}
 
-			uvaddr = MMAP_VADDR(ring->user_vstart,
-					    usr_idx, blkif_req.nr_segments);
-			kvaddr = request_to_kaddr(request,
-						  blkif_req.nr_segments);
+			uvaddr = MMAP_VADDR(ring->user_vstart, usr_idx, i);
+			kvaddr = request_to_kaddr(request, i);
 			offset = (uvaddr - ring->vma->vm_start) >> PAGE_SHIFT;
 			page   = pfn_to_page(__pa(kvaddr) >> PAGE_SHIFT);
 			ring->foreign_map.map[offset] = page;
@@ -654,10 +650,9 @@
 			      uvaddr, page, __pa(kvaddr) >> PAGE_SHIFT);
 			BTDBG("offset: 0x%08lx, pending_req: %p, seg: %d, "
 			      "page: %p, kvaddr: 0x%08lx, uvaddr: 0x%08lx\n",
-			      offset, request, blkif_req.nr_segments,
+			      offset, request, i,
 			      page, kvaddr, uvaddr);
 
-			blkif_req.nr_segments++;
 			request->nr_pages++;
 	}