From: Chris Murphy <lists@colorremedies.com>
To: Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc: Anand Jain <anand.jain@oracle.com>, Qu Wenruo <wqu@suse.com>,
David Sterba <dsterba@suse.cz>,
"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>,
Omar Sandoval <osandov@osandov.com>
Subject: Re: Seed device is broken, again.
Date: Mon, 28 Feb 2022 18:44:47 -0700 [thread overview]
Message-ID: <CAJCQCtSHCn7Pit7TgLJUTmMg9Tb87DdajDGDvM_bw=bsb8h_jg@mail.gmail.com> (raw)
In-Reply-To: <00f162f7-774c-b7d4-9d1f-e04cc89b2aee@gmx.com>
On Sun, Feb 27, 2022 at 7:35 PM Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>
> >> With method b, at least we can make dev add ioctl to be completely RW in
> >> the long run.
> >
> > Could you please add more clarity here? Very confusing.
>
> Isn't it an awful thing that device add ioctl can even be executed on a
> RO mounted fs?
I think it's more idiosyncratic than awful. It is definitely
confusing. But I think the explanation is that the ro mount is a VFS
option, not a Btrfs option. It only indicates we cannot write from
user space to this file system while it's ro. Btrfs still can,
including playing the tree log (and I assume it updates trees on disk,
even if ro but without notreelog.
There's a wide assortment of confusion in the `mount` command's
results. You just have to depend on rote memorization to know what
things are VFS or file system specific. Maybe it'd be nice if the
output were clearer but ...
/dev/nvme0n1p5 on /home type btrfs
(rw,noatime,seclabel,compress=zstd:1,ssd,space_cache=v2,subvolid=271,subvol=/home)
Is seclabel VFS? Or yet a third domain? Anyway, for example:
/dev/nvme0n1p5 on /home type btrfs
(VFS:rw,noatime,seclabel)(btrfs:compress=zstd:1,ssd,space_cache=v2,subvolid=271,subvol=/home)
--
Chris Murphy
next prev parent reply other threads:[~2022-03-01 1:45 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-25 10:08 Seed device is broken, again Qu Wenruo
2022-02-25 11:39 ` Filipe Manana
2022-02-25 11:47 ` David Sterba
2022-02-25 13:36 ` Qu Wenruo
2022-02-25 19:18 ` Omar Sandoval
2022-02-27 23:56 ` Qu Wenruo
2022-02-28 2:01 ` Anand Jain
2022-02-28 2:35 ` Qu Wenruo
2022-02-28 3:24 ` Anand Jain
2022-02-28 3:27 ` Qu Wenruo
2022-02-28 18:40 ` David Sterba
2022-03-01 0:13 ` Qu Wenruo
2022-03-01 1:49 ` Chris Murphy
2022-03-01 17:09 ` David Sterba
2022-03-02 0:00 ` Qu Wenruo
2022-03-01 1:44 ` Chris Murphy [this message]
2022-03-02 10:09 ` Neal Gompa
2022-02-25 12:00 ` Nikolay Borisov
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