From: Milan Broz <mbroz@redhat.com>

Limit the amount of memory allocated per snapshot on systems
with a large page size.  (The larger default chunk size on
these systems compensates for the smaller number of pages reserved.)

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---
 drivers/md/dm-snap.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6.25/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.25.orig/drivers/md/dm-snap.c	2008-04-24 17:43:47.000000000 +0100
+++ linux-2.6.25/drivers/md/dm-snap.c	2008-04-24 18:00:22.000000000 +0100
@@ -36,9 +36,9 @@
 #define SNAPSHOT_COPY_PRIORITY 2
 
 /*
- * Each snapshot reserves this many pages for io
+ * Reserve 1MB for each snapshot initially (with minimum of 1 page).
  */
-#define SNAPSHOT_PAGES 256
+#define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1)
 
 static struct workqueue_struct *ksnapd;
 static void flush_queued_bios(struct work_struct *work);