From 0262d1a48280b2b3d11d74ccb0660a229894c4be Mon Sep 17 00:00:00 2001
From: Steven Smith <ssmith@weybridge.uk.xensource.com>
Date: Tue, 30 Jun 2009 12:55:47 +0100
Subject: [PATCH] patch backend-track-pages-with-page-flags.patch

---
 drivers/xen/blkback/blkback.c |  3 +++
 drivers/xen/blktap/blktap.c   |  3 +++
 drivers/xen/core/gnttab.c     |  2 ++
 drivers/xen/netback/netback.c | 10 ++++++++--
 include/linux/page-flags.h    |  4 ++++
 5 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/blkback/blkback.c b/drivers/xen/blkback/blkback.c
index 6e9ef7b7..612f7c9b 100644
--- a/drivers/xen/blkback/blkback.c
+++ b/drivers/xen/blkback/blkback.c
@@ -623,6 +623,9 @@ static int __init blkif_init(void)
 					mmap_pages, GFP_KERNEL);
 	pending_pages         = alloc_empty_pages_and_pagevec(mmap_pages);
 
+	for(i = 0; i < mmap_pages; i++)
+		SetPageBlkback(pending_pages[i]);
+
 	if (!pending_reqs || !pending_grant_handles || !pending_pages)
 		goto out_of_memory;
 
diff --git a/drivers/xen/blktap/blktap.c b/drivers/xen/blktap/blktap.c
index 752382a8..cd555a8e 100644
--- a/drivers/xen/blktap/blktap.c
+++ b/drivers/xen/blktap/blktap.c
@@ -876,6 +876,9 @@ static int req_increase(void)
 	DPRINTK("%s: reqs=%d, pages=%d\n",
 		__FUNCTION__, blkif_reqs, mmap_pages);
 
+	for (i = 0; i < mmap_pages; i++)
+		SetPageBlkback(foreign_pages[mmap_alloc][i]);
+
 	for (i = 0; i < MAX_PENDING_REQS; i++) {
 		list_add_tail(&pending_reqs[mmap_alloc][i].free_list, 
 			      &pending_free);
diff --git a/drivers/xen/core/gnttab.c b/drivers/xen/core/gnttab.c
index 82c2e644..e6b4917b 100644
--- a/drivers/xen/core/gnttab.c
+++ b/drivers/xen/core/gnttab.c
@@ -593,6 +593,8 @@ int gnttab_copy_grant_page(grant_ref_t ref, struct page **pagep)
 	*pagep = new_page;
 
 	SetPageForeign(page, gnttab_page_free);
+	ClearPageNetback(page);
+	ClearPageBlkback(page);
 	page->mapping = NULL;
 
 out:
diff --git a/drivers/xen/netback/netback.c b/drivers/xen/netback/netback.c
index efa1d17d..cb2d5622 100644
--- a/drivers/xen/netback/netback.c
+++ b/drivers/xen/netback/netback.c
@@ -866,8 +866,13 @@ static void tx_credit_callback(unsigned long data)
 
 static inline int copy_pending_req(PEND_RING_IDX pending_idx)
 {
-	return gnttab_copy_grant_page(grant_tx_handle[pending_idx],
-				      &mmap_pages[pending_idx]);
+	int err = gnttab_copy_grant_page(grant_tx_handle[pending_idx],
+					&mmap_pages[pending_idx]);
+
+	if (!err)
+		SetPageNetback(mmap_pages[pending_idx]);
+
+	return err;
 }
 
 inline static void net_tx_action_dealloc(void)
@@ -1598,6 +1603,7 @@ static int __init netback_init(void)
 	for (i = 0; i < MAX_PENDING_REQS; i++) {
 		page = mmap_pages[i];
 		SetPageForeign(page, netif_page_release);
+		SetPageNetback(page);
 		netif_set_page_index(page, i);
 		INIT_LIST_HEAD(&pending_inuse[i].list);
 	}
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index ef187aa8..1d4e02da 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -104,6 +104,8 @@ enum pageflags {
 				 * bad_page() checks include this bit.
 				 * Should not use PG_arch_1 as that may have
 				 * a different purpose elsewhere. */
+	PG_netback,		/* Page is owned by netback */
+	PG_blkback,		/* Page is owned by blkback */
 #endif
 	__NR_PAGEFLAGS,
 
@@ -302,6 +304,8 @@ static inline void PageForeignDestructor(struct page *page, unsigned int order)
 {
 	((void (*)(struct page *, unsigned int))page->index)(page, order);
 }
+PAGEFLAG(Blkback, blkback)
+PAGEFLAG(Netback, netback)
 #endif
 
 extern void cancel_dirty_page(struct page *page, unsigned int account_size);
-- 
2.39.5