This message generated a parse failure. Raw output follows here. Please use 'back' to navigate. From devnull@lkml.org Fri Apr 26 16:01:22 2024 Received: from nic2.funet.fi (nic2.funet.fi [128.214.248.46]) by herbie.ucs.indiana.edu (8.9.3/8.9.3) with ESMTP id LAA13560 for ; Sun, 26 Sep 1999 11:31:12 -0500 (EST) Received: from vger.rutgers.edu ([128.6.190.2]:3844 "EHLO vger.rutgers.edu") by nic2.funet.fi with ESMTP id ; Sun, 26 Sep 1999 19:30:41 +0300 Received: by vger.rutgers.edu via listexpand id ; Sun, 26 Sep 1999 12:28:39 -0400 Received: by vger.rutgers.edu id ; Sun, 26 Sep 1999 12:28:20 -0400 Received: from [202.96.44.19] ([202.96.44.19]:2590 "HELO smtp.263.net") by vger.rutgers.edu with SMTP id ; Sun, 26 Sep 1999 12:28:06 -0400 Received: (fmail 23221 invoked from network); 26 Sep 1999 14:18:29 -0000 Received: from unknown (HELO 192.168.1.21) (210.78.135.162) by 202.96.44.19 with SMTP; 26 Sep 1999 14:18:29 -0000 Date: Sun, 26 Sep 1999 22:13:11 +0800 From: Song Jianping X-Mailer: The Bat! (v1.31) UNREG Reply-To: Song Jianping Organization: Tsinghua Univ. X-Priority: 3 (Normal) Message-Id: <7925.990926@263.net> To: linux-kernel@vger.rutgers.edu Subject: When will getblk() return NULL? Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-kernel@vger.rutgers.edu Precedence: bulk X-Loop: majordomo@vger.rutgers.edu X-Orcpt: rfc822;linux-kernel-outgoing-dig Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by herbie.ucs.indiana.edu id LAA13560 Hello all, In getblk()( in buffer.c ), there are just two "return" statement: if (bh) { if (!buffer_dirty(bh)) { if (buffer_uptodate(bh)) //最近访问过,如果不脏,且uptodate,放入表末尾 put_last_lru(bh); bh->b_flushtime = 0; } return bh; ^^^^^^^^^^ } and if( !bh ) goto refill; // bh can not be NULL now .... return bh; ^^^^^^^^ So it can not return NULL. But in block_read of block_dev.c,it assumes getblk() can return NULL, and in this case it will copy zero to user space "buf". Can anyone tell me when getblk() will return NULL? Many thanks, Song mailto:song.jpg@263.net:.炈洷殊m珉a娚b策靭wm呴b濓顬藳笔鈓閎烄戧鐉_鉃豝n噐■侂h櫒璀&{鄗侩贺辷沐y澏瓎踚鹈砘璁鍜i