From: "Aneesh Kumar K.V" Subject: [PATCH -V4 1/2] Fix sub-block zeroing for buffered writes into unwritten extents Date: Wed, 29 Apr 2009 10:17:20 +0530 Message-ID: <1240980441-8105-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Cc: linux-ext4@vger.kernel.org, "Aneesh Kumar K.V" To: cmm@us.ibm.com, tytso@mit.edu, sandeen@redhat.com Return-path: Received: from e23smtp06.au.ibm.com ([202.81.31.148]:59123 "EHLO e23smtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751545AbZD2Er1 (ORCPT ); Wed, 29 Apr 2009 00:47:27 -0400 Received: from d23relay02.au.ibm.com (d23relay02.au.ibm.com [202.81.31.244]) by e23smtp06.au.ibm.com (8.13.1/8.13.1) with ESMTP id n3T4lMe3030526 for ; Wed, 29 Apr 2009 14:47:22 +1000 Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay02.au.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n3T4lQRJ1544298 for ; Wed, 29 Apr 2009 14:47:26 +1000 Received: from d23av01.au.ibm.com (loopback [127.0.0.1]) by d23av01.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n3T4lPhw024733 for ; Wed, 29 Apr 2009 14:47:26 +1000 Sender: linux-ext4-owner@vger.kernel.org List-ID: We need to mark the buffer_head mapping prealloc space as new during write_begin. Otherwise we don't zero out the page cache content properly for a partial write. This will cause file corruption with preallocation. Also use block number -1 as the fake block number so that unmap_underlying_metadata doesn't drop wrong buffer_head Signed-off-by: Aneesh Kumar K.V --- fs/ext4/inode.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index e91f978..12dcfab 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2323,6 +2323,16 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock, set_buffer_delay(bh_result); } else if (ret > 0) { bh_result->b_size = (ret << inode->i_blkbits); + /* + * With sub-block writes into unwritten extents + * we also need to mark the buffer as new so that + * the unwritten parts of the buffer gets correctly zeroed. + */ + if (buffer_unwritten(bh_result)) { + bh_result->b_bdev = inode->i_sb->s_bdev; + set_buffer_new(bh_result); + bh_result->b_blocknr = -1; + } ret = 0; } -- tg: (56a50ad..) preallocate_corruption_quickfix (depends on: master)