nfs: fix nfs_size_to_loff_t

See http: //www.infradead.org/rpr.html
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We support OFFSET_MAX just fine, so don't round down below it.  Also
switch to using min_t to make the helper more readable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Fixes: 433c92379d9c ("NFS: Clean up nfs_size_to_loff_t()")
Cc: stable@vger.kernel.org # 2.6.23+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

include/linux/nfs_fs.h

@@ -550,9 +550,7 @@ extern int  nfs_readpage_async(struct nfs_open_context *, struct inode *,
 
 static inline loff_t nfs_size_to_loff_t(__u64 size)
 {
-	if (size > (__u64) OFFSET_MAX - 1)
-		return OFFSET_MAX - 1;
-	return (loff_t) size;
+	return min_t(u64, size, OFFSET_MAX);
 }
 
 static inline ino_t