From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cantor2.suse.de ([195.135.220.15]:39434 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751437AbaAMSlM (ORCPT ); Mon, 13 Jan 2014 13:41:12 -0500 Date: Mon, 13 Jan 2014 19:40:24 +0100 From: David Sterba To: Wang Shilong Cc: dsterba@suse.cz, Wang Shilong , linux-btrfs@vger.kernel.org Subject: Re: [PATCH v2 1/4] Btrfs: fix wrong send_in_progress accounting Message-ID: <20140113184024.GT6498@twin.jikos.cz> Reply-To: dsterba@suse.cz References: <1389086721-19624-1-git-send-email-wangsl.fnst@cn.fujitsu.com> <20140108121609.GF6498@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Wed, Jan 08, 2014 at 11:09:02PM +0800, Wang Shilong wrote: > > Hello David, > > > On Tue, Jan 07, 2014 at 05:25:18PM +0800, Wang Shilong wrote: > >> Steps to reproduce: > >> # mkfs.btrfs -f /dev/sda8 > >> # mount /dev/sda8 /mnt > >> # btrfs sub snapshot -r /mnt /mnt/snap1 > >> # btrfs sub snapshot -r /mnt /mnt/snap2 > >> # btrfs send /mnt/snap1 -p /mnt/snap2 -f /mnt/1 > >> # dmesg > >> > >> The problem is that we will sort clone roots(include @send_root), it > >> might push @send_root before thus @send_root's @send_in_progress will > >> be decreased twice. > > > > Of course, the sort(). I think your fix adds some complexity that's not > > necessary. Whether the clone_roots array is sorted is not important, we > > just have to process each root once. > > > > send_root becomes a clone_root member, so the missing part is to account > > in the rollback counter: > > > > --- a/fs/btrfs/send.c > > +++ b/fs/btrfs/send.c > > @@ -4937,6 +4937,7 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_) > > * for possible clone sources. > > */ > > sctx->clone_roots[sctx->clone_roots_cnt++].root = sctx->send_root; > > + clone_sources_to_rollback++; > > Not really, If we fail to come here, we still need decrease @send_root. Right. I was thinking if the code can be simplified somehow, but don't have anything vastly better. Can you please add a comment to the first branch that send_root is processed in the loop and not missed? It looks unabalanced when it's handled just a few lines below and not in the 1st loop. thanks, david