From: Steven Whitehouse Subject: Re: Motion to nuke FS_DIRECTIO_FL Date: Mon, 25 Jan 2010 09:31:27 +0000 Message-ID: <1264411887.2449.3.camel@localhost> References: <20090906092546.GU4197@webber.adilger.int> <20100124194839.GB4372@thunk.org> <20100125080610.GD4372@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Andreas Dilger , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org To: tytso@mit.edu Return-path: In-Reply-To: <20100125080610.GD4372@thunk.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Hi, On Mon, 2010-01-25 at 03:06 -0500, tytso@mit.edu wrote: > On Sun, Jan 24, 2010 at 11:18:47PM -0700, Andreas Dilger wrote: > > > > It doesn't seem that ext2/3/4 are using the 0x00100000 value itself, > > but it seems the VFS is using this value for FS_DIRECTIO_FL. Should > > we reserve this in the ext4 flags also, to avoid collisions? I'm > > not sure what that flag is for, possibly to force all IO to the file > > to be uncached? > > Hmm, absolutely nothing seems to use FS_DIRECTIO_FL; it looks like it > was introduced by GFS2 in commit 128e5eba in 2006 and then dropped in > commit c9f6a6bb in 2008, but we never killed the FS_DIRECTIO_FL flag > itself in include/linux/fs.h. > > The summary line for c9f6a6bb is a bit amusing: > > [GFS2] Remove support for unused and pointless flag > > Heh. > > Sounds like we should just kill it. Any objections? > > - Ted No. Sounds good to me. It was never used with GFS2 and it a left-over from GFS1 which had a flag allowing all "normal" I/O to be turned into O_DIRECT I/O depending on an inode flag. The idea failed due to alignment restrictions of course and nobody actually used it, Steve.