From: Eric Sandeen Subject: Re: [PATCH, RFC] ext4: add EXT4_IOC_ALLOC_DA_BLKS ioctl Date: Thu, 12 Mar 2009 11:32:18 -0500 Message-ID: <49B93912.804@redhat.com> References: <1235451952-2726-1-git-send-email-tytso@mit.edu> <1235451952-2726-2-git-send-email-tytso@mit.edu> <1235451952-2726-3-git-send-email-tytso@mit.edu> <1235451952-2726-4-git-send-email-tytso@mit.edu> <1235451952-2726-5-git-send-email-tytso@mit.edu> <49B83E01.1040605@redhat.com> <20090312052906.GA3033@skywalker> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Theodore Ts'o" , linux-ext4@vger.kernel.org To: "Aneesh Kumar K.V" Return-path: Received: from mx2.redhat.com ([66.187.237.31]:36516 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754419AbZCLQcf (ORCPT ); Thu, 12 Mar 2009 12:32:35 -0400 In-Reply-To: <20090312052906.GA3033@skywalker> Sender: linux-ext4-owner@vger.kernel.org List-ID: Aneesh Kumar K.V wrote: > On Wed, Mar 11, 2009 at 05:41:05PM -0500, Eric Sandeen wrote: >> Theodore Ts'o wrote: >>> Add an ioctl which forces all of the delay allocated blocks to be >>> allocated. This also provides a function ext4_alloc_da_blocks() which >>> will be used by the following commits to force files to be fully >>> allocated to preserve application-expected ext3 behaviour. >>> >> Is it worth checking whether a) the file has delalloc blocks, and/or b) >> whether the mapping is dirty before we spin off a filemap_flush? >> > +int ext4_alloc_da_blocks(struct inode *inode) > +{ > + if (!EXT4_I(inode)->i_reserved_data_blocks && > + !EXT4_I(inode)->i_reserved_meta_blocks) > + return 0; > > This check test does (a). Since the ioctl is to force allocation of > delayed allocated blocks i guess (a) is enough because we don't want to > cause a filemap_flush when we don't have any delayed allocated blocks > but have dirty pages around. and b) is as simple as if (!mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) return 0; I think? -Eric