From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:45814 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755458AbdESSLk (ORCPT ); Fri, 19 May 2017 14:11:40 -0400 Date: Fri, 19 May 2017 20:10:41 +0200 From: David Sterba To: Liu Bo Cc: jeffm@suse.com, linux-btrfs@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 1/3] btrfs: fix race with relocation recovery and fs_root setup Message-ID: <20170519181041.GZ4065@twin.jikos.cz> Reply-To: dsterba@suse.cz References: <1495035516-3217-1-git-send-email-jeffm@suse.com> <20170518235819.GD23822@lim.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170518235819.GD23822@lim.localdomain> Sender: stable-owner@vger.kernel.org List-ID: On Thu, May 18, 2017 at 04:58:19PM -0700, Liu Bo wrote: > On Wed, May 17, 2017 at 11:38:34AM -0400, jeffm@suse.com wrote: > > From: Jeff Mahoney > > > > If we have to recover relocation during mount, we'll ultimately have to > > evict the orphan inode. That goes through the reservation dance, where > > priority_reclaim_metadata_space and flush_space expect fs_info->fs_root > > to be valid. That's the next thing to be set up during mount, so we > > crash, almost always in flush_space trying to join the transaction > > but priority_reclaim_metadata_space is possible as well. This call > > path has been problematic in the past WRT whether ->fs_root is valid > > yet. Commit 957780eb278 (Btrfs: introduce ticketed enospc > > infrastructure) added new users that are called in the direct path > > instead of the async path that had already been worked around. > > > > The thing is that we don't actually need the fs_root, specifically, for > > anything. We either use it to determine whether the root is the > > chunk_root for use in choosing an allocation profile or as a root to pass > > btrfs_join_transaction before immediately committing it. Anything that > > isn't the chunk root works in the former case and any root works in > > the latter. > > > > A simple fix is to use a root we know will always be there: the > > extent_root. > > > Reviewed-by: Liu Bo 2-3 added to 4.13 queue, 1 will go to 4.12. Thanks.