From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:35757 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751818AbdLUPXj (ORCPT ); Thu, 21 Dec 2017 10:23:39 -0500 Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 80CABAEF0 for ; Thu, 21 Dec 2017 15:23:38 +0000 (UTC) Subject: Re: [PATCH 02/14] btrfs: qgroup: Introduce helpers to update and access new qgroup rsv To: Qu Wenruo , linux-btrfs@vger.kernel.org Cc: dsterba@suse.cz, jeffm@suse.com References: <20171212073436.16447-1-wqu@suse.com> <20171212073436.16447-3-wqu@suse.com> From: Nikolay Borisov Message-ID: Date: Thu, 21 Dec 2017 17:23:37 +0200 MIME-Version: 1.0 In-Reply-To: <20171212073436.16447-3-wqu@suse.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 12.12.2017 09:34, Qu Wenruo wrote: > Introduce helpers to: > > 1) Get total reserved space > For limit calculation > 2) Add/release reserved space for given type > With underflow detection and warning > 3) Add/release reserved space according to child qgroup > > Signed-off-by: Qu Wenruo > --- > fs/btrfs/qgroup.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 68 insertions(+) > > diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c > index f6fe28ca0e86..14346ff9a162 100644 > --- a/fs/btrfs/qgroup.c > +++ b/fs/btrfs/qgroup.c > @@ -47,6 +47,74 @@ > * - check all ioctl parameters > */ > > +/* > + * Helpers to access qgroup reservation > + * > + * Callers should ensure the lock context and type are valid > + */ > + > +static u64 qgroup_rsv_total(const struct btrfs_qgroup *qgroup) > +{ > + u64 ret = 0; > + int i; > + > + for (i = 0; i < BTRFS_QGROUP_RSV_LAST; i++) > + ret += qgroup->rsv.values[i]; > + > + return ret; > +} > + > +#ifdef CONFIG_BTRFS_DEBUG > +static const char *qgroup_rsv_type_str(enum btrfs_qgroup_rsv_type type) > +{ > + if (type == BTRFS_QGROUP_RSV_DATA) > + return "data"; > + if (type == BTRFS_QGROUP_RSV_META) > + return "meta"; > + return NULL; > +} > +#endif > + > +static void qgroup_rsv_add(struct btrfs_qgroup *qgroup, u64 num_bytes, > + enum btrfs_qgroup_rsv_type type) > +{ > + qgroup->rsv.values[type] += num_bytes; > +} > + > +static void qgroup_rsv_release(struct btrfs_qgroup *qgroup, u64 num_bytes, > + enum btrfs_qgroup_rsv_type type) > +{ > + if (qgroup->rsv.values[type] >= num_bytes) { > + qgroup->rsv.values[type] -= num_bytes; > + return; > + } nit: Generally I'd prefer that the if tests for the exceptional condition and handle it inside i.e. we expect most of the time for underflow to not occur. Not a big deal so doesn't warrant a resend but something to think about in the future. > +#ifdef CONFIG_BTRFS_DEBUG > + WARN_RATELIMIT(1, > + "qgroup %llu %s reserved space underflow, have %llu to free %llu", > + qgroup->qgroupid, qgroup_rsv_type_str(type), > + qgroup->rsv.values[type], num_bytes); > +#endif > + qgroup->rsv.values[type] = 0; > +} > + > +static void qgroup_rsv_add_by_qgroup(struct btrfs_qgroup *dest, > + struct btrfs_qgroup *src) > +{ > + int i; > + > + for (i = 0; i < BTRFS_QGROUP_RSV_LAST; i++) > + qgroup_rsv_add(dest, src->rsv.values[i], i); > +} > + > +static void qgroup_rsv_release_by_qgroup(struct btrfs_qgroup *dest, > + struct btrfs_qgroup *src) > +{ > + int i; > + > + for (i = 0; i < BTRFS_QGROUP_RSV_LAST; i++) > + qgroup_rsv_release(dest, src->rsv.values[i], i); > +} > + > static void btrfs_qgroup_update_old_refcnt(struct btrfs_qgroup *qg, u64 seq, > int mod) > { >