From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cantor2.suse.de ([195.135.220.15]:52448 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755200AbaAHMQL (ORCPT ); Wed, 8 Jan 2014 07:16:11 -0500 Date: Wed, 8 Jan 2014 13:16:09 +0100 From: David Sterba To: Wang Shilong Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH v2 1/4] Btrfs: fix wrong send_in_progress accounting Message-ID: <20140108121609.GF6498@suse.cz> Reply-To: dsterba@suse.cz References: <1389086721-19624-1-git-send-email-wangsl.fnst@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1389086721-19624-1-git-send-email-wangsl.fnst@cn.fujitsu.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: 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++; /* We do a bsearch later */ sort(sctx->clone_roots, sctx->clone_roots_cnt, @@ -4961,7 +4962,6 @@ out: btrfs_root_dec_send_in_progress(sctx->clone_roots[i].root); if (sctx && !IS_ERR_OR_NULL(sctx->parent_root)) btrfs_root_dec_send_in_progress(sctx->parent_root); - btrfs_root_dec_send_in_progress(send_root); kfree(arg); vfree(clone_sources_tmp); ---