From: Jan Kara Subject: [PATCH 2/2] ext4: Fix buffer dirtying in data=journal mode Date: Mon, 21 Jun 2010 12:42:53 +0200 Message-ID: <1277116973-4183-3-git-send-email-jack@suse.cz> References: <1277116973-4183-1-git-send-email-jack@suse.cz> Cc: Jan Kara , tytso@mit.edu To: linux-ext4@vger.kernel.org Return-path: Received: from cantor2.suse.de ([195.135.220.15]:57117 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932176Ab0FUKn1 (ORCPT ); Mon, 21 Jun 2010 06:43:27 -0400 In-Reply-To: <1277116973-4183-1-git-send-email-jack@suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: block_prepare_write() can dirty freshly created buffer. This is a problem for data=journal mode because data buffers shouldn't be dirty unless they are undergoing checkpoint. So we have to tweak get_block function for data=journal mode to catch the case when block_prepare_write would dirty the buffer, do the work instead of block_prepare_write, and properly handle dirty buffer as data=journal mode requires it. It might be cleaner to avoid using block_prepare_write() for data=journal mode writes but that would require us to duplicate most of the function which isn't nice either... CC: tytso@mit.edu Signed-off-by: Jan Kara --- fs/ext4/inode.c | 47 +++++++++++++++++++++++++++++++++++++++++++---- 1 files changed, 43 insertions(+), 4 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 81d6054..526404b 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1388,6 +1388,43 @@ out: return ret; } +static int ext4_journalled_get_block(struct inode *inode, sector_t iblock, + struct buffer_head *bh, int create) +{ + handle_t *handle = ext4_journal_current_handle(); + int ret; + + /* This function should ever be used only for real buffers */ + BUG_ON(!bh->b_page); + + ret = ext4_get_blocks(handle, inode, iblock, 1, bh, + create ? EXT4_GET_BLOCKS_CREATE : 0); + if (ret > 0) { + if (buffer_new(bh)) { + struct page *page = bh->b_page; + + /* + * This is a terrible hack to avoid block_prepare_write + * marking our buffer as dirty + */ + if (PageUptodate(page)) { + ret = ext4_journal_get_write_access(handle, bh); + if (ret < 0) + return ret; + unmap_underlying_metadata(bh->b_bdev, + bh->b_blocknr); + clear_buffer_new(bh); + set_buffer_uptodate(bh); + ret = jbd2_journal_dirty_metadata(handle, bh); + if (ret < 0) + return ret; + } + } + ret = 0; + } + return ret; +} + /* * `handle' can be NULL if create is zero */ @@ -1599,12 +1636,14 @@ retry: if (ext4_should_dioread_nolock(inode)) ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata, ext4_get_block_write); - else + else if (!ext4_should_journal_data(inode)) ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata, ext4_get_block);