NFSv2: Fix eof handling

[ Upstream commit 71affe9be45a5c60b9772e1b2701710712637274 ]

If we received a reply from the server with a zero length read and
no error, then that implies we are at eof.
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>

fs/nfs/proc.c

@@ -594,7 +594,8 @@ static int nfs_read_done(struct rpc_task *task, struct nfs_pgio_header *hdr)
 		/* Emulate the eof flag, which isn't normally needed in NFSv2
 		 * as it is guaranteed to always return the file attributes
 		 */
-		if (hdr->args.offset + hdr->res.count >= hdr->res.fattr->size)
+		if ((hdr->res.count == 0 && hdr->args.count > 0) ||
+		    hdr->args.offset + hdr->res.count >= hdr->res.fattr->size)
 			hdr->res.eof = 1;
 	}
 	return 0;