From: Alex Elder <elder@inktank.com>
Date: Wed, 3 Apr 2013 20:03:53 +0000 (-0500)
Subject: ceph: use page_offset() in ceph_writepages_start()
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=25d71cb92d8eb48df9cbd8cc4bb28e88ee8e88d9;p=deliverable%2Flinux.git

ceph: use page_offset() in ceph_writepages_start()

There's one spot in ceph_writepages_start() that open-codes what
page_offset() does safely.  Use the macro so we don't have to worry
about wrapping.

This resolves:
    http://tracker.ceph.com/issues/4648

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
---

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 45745aae4786..ae438d02a422 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -900,7 +900,7 @@ get_more_pages:
 		}
 
 		/* submit the write */
-		offset = req->r_data_out.pages[0]->index << PAGE_CACHE_SHIFT;
+		offset = page_offset(req->r_data_out.pages[0]);
 		len = min((snap_size ? snap_size : i_size_read(inode)) - offset,
 			  (u64)locked_pages << PAGE_CACHE_SHIFT);
 		dout("writepages got %d pages at %llu~%llu\n",