[PATCH] revoke: break cow fixes

[Pekka J Enberg]

From: Pekka Enberg <penberg@xxxxxxxxxxxxxx>

As pointed out by Nick Piggin, __revoke_break_cow() only needs to do
down_read() and we must use vma_pages() for get_user_pages().

Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Signed-off-by: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
---
 fs/revoke.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

Index: uml-2.6/fs/revoke.c
===================================================================
--- uml-2.6.orig/fs/revoke.c	2007-03-28 12:25:29.000000000 +0300
+++ uml-2.6/fs/revoke.c	2007-03-28 12:54:49.000000000 +0300
@@ -184,7 +184,7 @@ static int __revoke_break_cow(struct tas
 	struct vm_area_struct *vma;
 	int err = 0;
 
-	down_write(&mm->mmap_sem);
+	down_read(&mm->mmap_sem);
 	for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
 		int ret;
 
@@ -195,14 +195,13 @@ 	int err = 0;
 			continue;
 
 		ret = get_user_pages(tsk, tsk->mm, vma->vm_start,
-				     vma->vm_end-vma->vm_start, 1, 1, NULL,
-				     NULL);
+				     vma_pages(vma), 1, 1, NULL, NULL);
 		if (ret < 0) {
 			err = ret;
 			break;
 		}
 	}
-	up_write(&mm->mmap_sem);
+	up_read(&mm->mmap_sem);
 	return err;
 }
 
-
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