From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:38974 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752183AbeGBHtt (ORCPT ); Mon, 2 Jul 2018 03:49:49 -0400 Subject: Re: [PATCH] btrfs: use correct compare function of dirty_metadata_bytes To: Ethan Lien , linux-btrfs@vger.kernel.org References: <20180702074458.16270-1-ethanlien@synology.com> From: Nikolay Borisov Message-ID: <068bb6e1-78b9-ed1c-f9e2-08e90de5e928@suse.com> Date: Mon, 2 Jul 2018 10:49:46 +0300 MIME-Version: 1.0 In-Reply-To: <20180702074458.16270-1-ethanlien@synology.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2.07.2018 10:44, Ethan Lien wrote: > We use customized, nodesize batch value to update dirty_metadata_bytes. > We should also use batch version of compare function or we will easily > goto fast path and get false result from percpu_counter_compare(). > > Signed-off-by: Ethan Lien Reviewed-by: Nikolay Borisov Also this needs the following tag: Fixes: e2d845211eda ("Btrfs: use percpu counter for dirty metadata count") And perhaps stable from 4.4 onwards. But David will take care of that. So the patch is good. > --- > fs/btrfs/disk-io.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index 205092dc9390..dfed08e70ec1 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -961,8 +961,9 @@ static int btree_writepages(struct address_space *mapping, > > fs_info = BTRFS_I(mapping->host)->root->fs_info; > /* this is a bit racy, but that's ok */ > - ret = percpu_counter_compare(&fs_info->dirty_metadata_bytes, > - BTRFS_DIRTY_METADATA_THRESH); > + ret = __percpu_counter_compare(&fs_info->dirty_metadata_bytes, > + BTRFS_DIRTY_METADATA_THRESH, > + fs_info->dirty_metadata_batch); > if (ret < 0) > return 0; > } > @@ -4150,8 +4151,9 @@ static void __btrfs_btree_balance_dirty(struct btrfs_fs_info *fs_info, > if (flush_delayed) > btrfs_balance_delayed_items(fs_info); > > - ret = percpu_counter_compare(&fs_info->dirty_metadata_bytes, > - BTRFS_DIRTY_METADATA_THRESH); > + ret = __percpu_counter_compare(&fs_info->dirty_metadata_bytes, > + BTRFS_DIRTY_METADATA_THRESH, > + fs_info->dirty_metadata_batch); > if (ret > 0) { > balance_dirty_pages_ratelimited(fs_info->btree_inode->i_mapping); > } >