nfs: fix nfs_size_to_loff_t

commit 50ab8ec7 upstream.

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: 433c9237 ("NFS: Clean up nfs_size_to_loff_t()")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

include/linux/nfs_fs.h

@@ -589,9 +589,7 @@ static inline void nfs3_forget_cached_acls(struct inode *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