From 46b46554c01c9be10ffd80ec288449e5e61a79cc Mon Sep 17 00:00:00 2001
From: t_jeang <devnull@localhost>
Date: Tue, 6 Jan 2009 12:06:01 +0000
Subject: [PATCH] imported 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    | 10 ++++++++++
 5 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/blkback/blkback.c b/drivers/xen/blkback/blkback.c
index e75c1db8..4b8b5ba6 100644
--- a/drivers/xen/blkback/blkback.c
+++ b/drivers/xen/blkback/blkback.c
@@ -615,6 +615,9 @@ 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 5b00751d..a2f51ce7 100644
--- a/drivers/xen/blktap/blktap.c
+++ b/drivers/xen/blktap/blktap.c
@@ -875,6 +875,9 @@ 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 fd83ea0b..9b1e4d24 100644
--- a/drivers/xen/core/gnttab.c
+++ b/drivers/xen/core/gnttab.c
@@ -589,6 +589,8 @@ 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 145f67db..d771bf06 100644
--- a/drivers/xen/netback/netback.c
+++ b/drivers/xen/netback/netback.c
@@ -863,8 +863,13 @@ 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)
@@ -1590,6 +1595,7 @@ 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 cab8551b..e2f91529 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -104,6 +104,16 @@
 
 #define PG_foreign		20	/* Page is owned by foreign allocator. */
 
+#define PG_netback		21	/* Page is owned by netback */
+#define PageNetback(page)	test_bit(PG_netback, &(page)->flags)
+#define SetPageNetback(page)	set_bit(PG_netback, &(page)->flags)
+#define ClearPageNetback(page)	clear_bit(PG_netback, &(page)->flags)
+
+#define PG_blkback		22	/* Page is owned by blkback */
+#define PageBlkback(page)	test_bit(PG_blkback, &(page)->flags)
+#define SetPageBlkback(page)	set_bit(PG_blkback, &(page)->flags)
+#define ClearPageBlkback(page)	clear_bit(PG_blkback, &(page)->flags)
+
 /*
  * Manipulation of page state flags
  */
-- 
2.39.5