From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756888Ab0EZKNd (ORCPT ); Wed, 26 May 2010 06:13:33 -0400 Received: from hera.amn.nl ([213.189.22.5]:1689 "EHLO AMN.nl" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753285Ab0EZKNc (ORCPT ); Wed, 26 May 2010 06:13:32 -0400 X-Greylist: delayed 591 seconds by postgrey-1.27 at vger.kernel.org; Wed, 26 May 2010 06:13:31 EDT Message-ID: <4BFCF1EB.20709@cs.vu.nl> Date: Wed, 26 May 2010 12:03:23 +0200 From: Erik van der Kouwe User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) MIME-Version: 1.0 To: Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org CC: Fam Zheng Subject: [PATCH] fs/minix: bugfix, number of indirect block ptrs per block depends on block size Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit AMN-SPF: NONE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Erik van der Kouwe The MINIX filesystem driver used a constant number of indirect block pointers in an indirect block. This worked only for filesystems with 1kb block, while the MINIX default block size is now 4kb. As a consequence, large files were read incorrectly on such filesystems and writing a large file would cause the filesystem to become corrupted. This patch computes the number of indirect block pointers based on the block size, making the driver work for each block size. I would like to thank Feiran Zheng ('Fam') for pointing out the cause of the corruption. Signed-off-by: Erik van der Kouwe --- --- fs/minix/itree_v2.c.orig 2010-05-26 14:10:15.000000000 +0200 +++ fs/minix/itree_v2.c 2010-05-26 13:44:53.000000000 +0200 @@ -20,6 +20,9 @@ static inline block_t *i_data(struct ino return (block_t *)minix_i(inode)->u.i2_data; } +#define DIRCOUNT 7 +#define INDIRCOUNT(sb) ((sb)->s_blocksize / 4) + static int block_to_path(struct inode * inode, long block, int offsets[DEPTH]) { int n = 0; @@ -34,21 +37,21 @@ static int block_to_path(struct inode * printk("MINIX-fs: block_to_path: " "block %ld too big on dev %s\n", block, bdevname(sb->s_bdev, b)); - } else if (block < 7) { + } else if (block < DIRCOUNT) { offsets[n++] = block; - } else if ((block -= 7) < 256) { - offsets[n++] = 7; + } else if ((block -= DIRCOUNT) < INDIRCOUNT(sb)) { + offsets[n++] = DIRCOUNT; offsets[n++] = block; - } else if ((block -= 256) < 256*256) { - offsets[n++] = 8; - offsets[n++] = block>>8; - offsets[n++] = block & 255; + } else if ((block -= INDIRCOUNT(sb)) < INDIRCOUNT(sb) * INDIRCOUNT(sb)) { + offsets[n++] = DIRCOUNT + 1; + offsets[n++] = block / INDIRCOUNT(sb); + offsets[n++] = block % INDIRCOUNT(sb); } else { - block -= 256*256; - offsets[n++] = 9; - offsets[n++] = block>>16; - offsets[n++] = (block>>8) & 255; - offsets[n++] = block & 255; + block -= INDIRCOUNT(sb) * INDIRCOUNT(sb); + offsets[n++] = DIRCOUNT + 2; + offsets[n++] = (block / INDIRCOUNT(sb)) / INDIRCOUNT(sb); + offsets[n++] = (block / INDIRCOUNT(sb)) % INDIRCOUNT(sb); + offsets[n++] = block % INDIRCOUNT(sb); } return n; }