From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Wed, 12 Feb 2014 14:36:59 +0000 (-0500)
Subject: NFSv4.1: Fix wraparound issues in pnfs_seqid_is_newer()
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=2c64c57dfc4b7946f7abd8af653f55af581bc2c3;p=deliverable%2Flinux.git

NFSv4.1: Fix wraparound issues in pnfs_seqid_is_newer()

Subtraction of signed integers does not have well defined wraparound
semantics in the C99 standard. In order to be wraparound-safe, we
have to use unsigned subtraction, and then cast the result.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 4755858e37a0..6e67ada6c22c 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -662,7 +662,7 @@ pnfs_destroy_all_layouts(struct nfs_client *clp)
  */
 static bool pnfs_seqid_is_newer(u32 s1, u32 s2)
 {
-	return (s32)s1 - (s32)s2 > 0;
+	return (s32)(s1 - s2) > 0;
 }
 
 /* update lo->plh_stateid with new if is more recent */