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From: Sascha Hauer <s.hauer@pengutronix.de>
To: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@infradead.org>,
	linux-fsdevel@vger.kernel.org,
	Richard Weinberger <richard@nod.at>,
	linux-mtd@lists.infradead.org, kernel@pengutronix.de,
	Jan Kara <jack@suse.com>
Subject: Re: [PATCH 1/8] quota: Allow to pass mount path to quotactl
Date: Wed, 27 Jan 2021 15:05:10 +0100	[thread overview]
Message-ID: <20210127140510.GI28722@pengutronix.de> (raw)
In-Reply-To: <20210126161829.GG10966@quack2.suse.cz>

On Tue, Jan 26, 2021 at 05:18:29PM +0100, Jan Kara wrote:
> On Tue 26-01-21 13:34:06, Christoph Hellwig wrote:
> > On Tue, Jan 26, 2021 at 02:17:52PM +0100, Jan Kara wrote:
> > > Well, I don't think that "wait until unfrozen" is that strange e.g. for
> > > Q_SETQUOTA - it behaves like setxattr() or any other filesystem
> > > modification operation. And IMO it is desirable that filesystem freezing is
> > > transparent for operations like these. For stuff like Q_QUOTAON, I agree
> > > that returning EBUSY makes sense but then I'm not convinced it's really
> > > simpler or more useful behavior...
> > 
> > If we want it to behave like other syscalls we'll just need to throw in
> > a mnt_want_write/mnt_drop_write pair.  Than it behaves exactly like other
> > syscalls.
> 
> Right, we could do that. I'd just note that the "wait until unfrozen" and
> holding of sb->s_umount semaphore is equivalent to
> mnt_want_write/mnt_drop_write pair. But I agree
> mnt_want_write/mnt_drop_write is easier to understand and there's no reason
> not to use it. So I'm for that simplification in the new syscall.

Due to the user_path_at() to the mountpoint the fs won't go away, so I
guess for non-exclusive, non-write quota command I don't need any
additional locking. For non-exclusive, write commands I'll need a
mnt_want_write/mnt_drop_write pair. What about the exclusive, write
commands (Q_QUOTAON/Q_QUOTAOFF)?

Sascha

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  reply	other threads:[~2021-01-27 14:07 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-22 15:15 [PATCH v5 0/8] Add quota support to UBIFS Sascha Hauer
2021-01-22 15:15 ` [PATCH 1/8] quota: Allow to pass mount path to quotactl Sascha Hauer
2021-01-22 17:16   ` Christoph Hellwig
2021-01-25  8:38     ` Sascha Hauer
2021-01-25 15:45       ` Jan Kara
2021-01-25 20:42         ` Christoph Hellwig
2021-01-26 13:17           ` Jan Kara
2021-01-26 13:34             ` Christoph Hellwig
2021-01-26 16:18               ` Jan Kara
2021-01-27 14:05                 ` Sascha Hauer [this message]
2021-01-27 14:19                   ` Jan Kara
2021-01-26 10:45         ` Sascha Hauer
2021-01-27 14:46           ` Jan Kara
2021-01-27 16:25             ` Christoph Hellwig
2021-01-22 15:15 ` [PATCH 2/8] ubifs: move checks and preparation into setflags() Sascha Hauer
2021-01-22 15:15 ` [PATCH 3/8] ubifs: Add support for FS_IOC_FS[SG]ETXATTR ioctls Sascha Hauer
2021-01-22 17:18   ` Christoph Hellwig
2021-01-22 15:15 ` [PATCH 4/8] ubifs: do not ubifs_inode() on potentially NULL pointer Sascha Hauer
2021-01-22 15:15 ` [PATCH 5/8] ubifs: Factor out ubifs_set_feature_flag() Sascha Hauer
2021-01-22 15:15 ` [PATCH 6/8] ubifs: Add support for project id Sascha Hauer
2021-01-22 15:15 ` [PATCH 7/8] ubifs: export get_znode Sascha Hauer
2021-01-22 17:20   ` Christoph Hellwig
2021-01-22 15:15 ` [PATCH 8/8] ubifs: Add quota support Sascha Hauer
  -- strict thread matches above, loose matches on Subject: below --
2020-01-24 13:13 [PATCH v4 0/8] Add quota support to UBIFS Sascha Hauer
2020-01-24 13:13 ` [PATCH 1/8] quota: Allow to pass mount path to quotactl Sascha Hauer
2020-01-27 10:45   ` Jan Kara
2020-01-28 10:06     ` Sascha Hauer
2020-01-28 11:41       ` Jan Kara
2020-01-29  1:29       ` Al Viro
2020-01-29 16:14         ` Jan Kara
2020-02-04 10:35         ` Sascha Hauer
2020-02-18  9:22           ` Jan Kara

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