From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc: dsterba@suse.cz, Qu Wenruo <wqu@suse.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 1/5] btrfs: sysfs: introduce qgroup global attribute groups
Date: Fri, 3 Sep 2021 16:03:58 +0200 [thread overview]
Message-ID: <20210903140358.GF3379@twin.jikos.cz> (raw)
In-Reply-To: <9f48f55f-a4f3-ad0c-e48e-1da02b0ef068@gmx.com>
On Fri, Sep 03, 2021 at 06:30:36AM +0800, Qu Wenruo wrote:
>
>
> On 2021/9/3 上午12:28, David Sterba wrote:
> > On Tue, Aug 31, 2021 at 05:48:59PM +0800, Qu Wenruo wrote:
> >> Although we already have info kobject for each qgroup, we don't have
> >> global qgroup info attributes to show things like qgroup flags.
> >>
> >> Add this qgroups attribute groups, and the first member is qgroup_flags,
> >> which is a read-only attribute to show human readable qgroup flags.
> >>
> >> The path is:
> >> /sys/fs/btrfs/<uuid>/qgroups/qgroup_flags
> >>
> >> The output would look like:
> >> ON | INCONSISTENT
> >
> > So that's another format of sysfs file, we should try to keep them
> > consistent or follow common practices. The recommended way for sysfs is
> > to have one file per value, and here it follows the known states.
> >
> > So eg
> >
> > /sys/fs/.../qgroups/enabled -> 0 or 1
> > /sys/fs/.../qgroups/inconsistent -> 0 or 1
> > ...
> >
> > The files can be also writable so rescan can be triggered from sysfs, or
> > quotas disabled eventually. For the start exporting the state would be
> > sufficient though.
> >
> OK, that sounds indeed better than the current solution.
>
> Although there may be a small window that one reading 3 attributes could
> get inconsistent view, as it's no longer atomic.
>
> Would that be a problem?
I hope not, the status can change after reading the sysfs files anyway.
next prev parent reply other threads:[~2021-09-03 14:04 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-31 9:48 [PATCH 0/5] btrfs: qgroup: address the performance penalty for subvolume dropping Qu Wenruo
2021-08-31 9:48 ` [PATCH 1/5] btrfs: sysfs: introduce qgroup global attribute groups Qu Wenruo
2021-09-02 16:28 ` David Sterba
2021-09-02 22:30 ` Qu Wenruo
2021-09-03 14:03 ` David Sterba [this message]
2021-08-31 9:49 ` [PATCH 2/5] btrfs: introduce BTRFS_QGROUP_STATUS_FLAGS_MASK for later expansion Qu Wenruo
2021-08-31 9:49 ` [PATCH 3/5] btrfs: introduce BTRFS_QGROUP_RUNTIME_FLAG_CANCEL_RESCAN Qu Wenruo
2021-08-31 9:49 ` [PATCH 4/5] btrfs: introduce BTRFS_QGROUP_RUNTIME_FLAG_NO_ACCOUNTING to skip qgroup accounting Qu Wenruo
2021-08-31 9:49 ` [PATCH 5/5] btrfs: skip subtree scan if it's too high to avoid low stall in btrfs_commit_transaction() Qu Wenruo
2021-09-02 16:25 ` [PATCH 0/5] btrfs: qgroup: address the performance penalty for subvolume dropping David Sterba
2021-09-02 22:28 ` Qu Wenruo
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