[PATCH] md: don't allow new md/bitmap file to be set if one already exists

... otherwise we loose a reference and can never free the file.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 373ab92..63c5661 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2430,7 +2430,7 @@
 {
 	int err;
 
-	if (mddev->pers)
+	if (mddev->pers || mddev->bitmap_file)
 		return -EBUSY;
 
 	mddev->bitmap_file = fget(fd);