From: Jan Kara Subject: Re: [PATCH] ext4: make sure to revoke all the freeable blocks in ext4_free_blocks Date: Wed, 16 Dec 2015 10:44:15 +0100 Message-ID: <20151216094415.GC8968@quack.suse.cz> References: <1450225243-9085-1-git-send-email-daeho.jeong@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: tytso@mit.edu, jack@suse.cz, linux-ext4@vger.kernel.org To: Daeho Jeong Return-path: Received: from mx2.suse.de ([195.135.220.15]:35009 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754739AbbLPJoS (ORCPT ); Wed, 16 Dec 2015 04:44:18 -0500 Content-Disposition: inline In-Reply-To: <1450225243-9085-1-git-send-email-daeho.jeong@samsung.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed 16-12-15 09:20:43, Daeho Jeong wrote: > Now, ext4_free_blocks() doesn't revoke data blocks of per-file data > journalled inode and it can cause file data inconsistency problems. > Even though data blocks of per-file data journalled inode are already > forgotten by jbd2_journal_invalidatepage() in advance of invoking > ext4_free_blocks(), we still need to revoke the data blocks here. > Moreover some of the metadata blocks, which are not found by > sb_find_get_block(), are still needed to be revoked, but this is also > missing here. Thanks for looking into the issue! Just one small nit below. > Signed-off-by: Daeho Jeong > --- > fs/ext4/mballoc.c | 29 ++++++++++++++--------------- > 1 file changed, 14 insertions(+), 15 deletions(-) ... > + /* > + * We need to make sure we don't reuse the freed block until > + * after the transaction is committed, which we can do by > + * treating the block as metadata, below. We make an > + * exception if the inode is to be written in writeback mode > + * since writeback mode has weak data consistency guarantees. > + */ > + if (!ext4_should_writeback_data(inode)) > + flags |= EXT4_FREE_BLOCKS_METADATA; > + I think it would be clearer what's going on if your just modified the condition checking whether EFD entry needs to be created. Like: - if ((flags & EXT4_FREE_BLOCKS_METADATA) && ext4_handle_valid(handle)) { + /* + * We need to make sure we don't reuse the freed block until after the + * transaction is committed. We make an exception if the inode is to be + * written in writeback mode since writeback mode has weak data + * consistency guarantees. + */ + if (ext4_handle_valid(handle) && + ((flags & EXT4_FREE_BLOCKS_METADATA) || + !ext4_should_writeback_data(inode))) { struct ext4_free_data *new_entry; /* - * blocks being freed are metadata. these blocks shouldn't - * be used until this transaction is committed - * * We use __GFP_NOFAIL because ext4_free_blocks() is not * allowed * to fail. Otherwise the patch looks fine so after changing this feel free to add: Reviewed-by: Jan Kara Honza -- Jan Kara SUSE Labs, CR