From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from imap.thunk.org ([74.207.234.97]:55840 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752435AbaK0UUF (ORCPT ); Thu, 27 Nov 2014 15:20:05 -0500 Date: Thu, 27 Nov 2014 15:19:54 -0500 From: "Theodore Ts'o" To: Jan Kara Cc: Linux Filesystem Development List , Ext4 Developers List , Linux btrfs Developers List , XFS Developers Subject: Re: [PATCH-v4 2/7] vfs: add support for a lazytime mount option Message-ID: <20141127201954.GF14091@thunk.org> References: <1416997437-26092-1-git-send-email-tytso@mit.edu> <1416997437-26092-3-git-send-email-tytso@mit.edu> <20141127131421.GE30152@quack.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20141127131421.GE30152@quack.suse.cz> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Thu, Nov 27, 2014 at 02:14:21PM +0100, Jan Kara wrote: > Looking into the code & your patch I'd prefer to do something like: > * add support for I_DIRTY_TIME in __mark_inode_dirty() - update_time will > call __mark_inode_dirty() with this flag if any of the times was updated. > That way we can just remove your ->write_time() callback - filesystems > can just handle this in their ->dirty_inode() methods if they wish. > __mark_inode_dirty() will take care of moving inode into proper writeback > list (i_dirty / i_dirty_time), dirtied_when will be set to current time. One of the tricky bits about this is that btrfs wants to be able to return an error from write_time() which gets reflected up through update_time() to the callers of file_update_time(). Currently __mark_inode_dirty() and family return a void, and changing this is going to be a bit of a mess, since doing this correctly would require auditing all of the callers of mark_inode_dirty(), mark_inode_dirty_sync(), __mark_inode_dirty(), etc. Doing this would be a good thing, and eventually I think it would be nice if we could allow the mark_inode_dirty() functions return an error instead of void, but I wonder if that's a cleanup that's better saved for later. While we were at it, maybe we should rename mark_inode_dirty() to inode_dirty(), since that way we can be sure we've looked at all of the call site of mark_inode_dirty() and friends --- and we have a number of file systems, including btrfs, ext3, and ext4, where mark_inode_dirty() is doing a lot more than just marking the inode is dirty, and the only reason why it's named that is mostly historical. - Ted