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From: Jan Kara <jack@suse.cz>
To: Ira Weiny <ira.weiny@intel.com>
Cc: "Theodore Y. Ts'o" <tytso@mit.edu>,
	Ext4 Developers List <linux-ext4@vger.kernel.org>,
	syzkaller-bugs@googlegroups.com, stable@kernel.org,
	syzbot+bca9799bf129256190da@syzkaller.appspotmail.com
Subject: Re: [PATCH] ext4: reject mount options not supported when remounting in handle_mount_opt()
Date: Wed, 22 Apr 2020 18:10:29 +0200	[thread overview]
Message-ID: <20200422161029.GD20756@quack2.suse.cz> (raw)
In-Reply-To: <20200416052352.GK2309605@iweiny-DESK2.sc.intel.com>

On Wed 15-04-20 22:23:52, Ira Weiny wrote:
> On Wed, Apr 15, 2020 at 06:07:52PM -0400, Theodore Y. Ts'o wrote:
> > On Wed, Apr 15, 2020 at 01:25:37PM -0700, Ira Weiny wrote:
> > > This fundamentally changes the behavior from forcing the dax mode to be the
> > > same across the remount to only failing if we are going from non-dax to dax,
> > > adding -o dax on the remount?
> > > 
> > > But going from -o dax to 'not -o dax' would be ok?
> > > 
> > > FWIW after thinking about it some I _think_ it would be ok to allow the dax
> > > mode to change on a remount and let the inodes in memory stay in the mode they
> > > are at.  And newly loaded inodes would get the new mode...  Unfortunately
> > > without the STATX patch I have proposed the user does not have any way of
> > > knowing which files are in which mode.
> > 
> > We don't currently support mount -o nodax.
> 
> But we do support not supplying the option which means 'nodax' right?

Yeah, I second what Ira wrote. The new code does not seem to properly
detect a case when enabled mount option is removed for remount and thus the
feature would get disabled during remount as a result...

								Honza

-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply	other threads:[~2020-04-22 16:10 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <to=00000000000098a5d505a34d1e48@google.com>
2020-04-15 17:48 ` [PATCH] ext4: reject mount options not supported when remounting in handle_mount_opt() Theodore Ts'o
2020-04-15 18:12   ` Andreas Dilger
2020-04-15 20:25   ` Ira Weiny
2020-04-15 22:07     ` Theodore Y. Ts'o
2020-04-16  5:23       ` Ira Weiny
2020-04-22 16:10         ` Jan Kara [this message]
2020-05-14 14:34           ` Theodore Y. Ts'o
2020-05-16  1:49             ` Ira Weiny

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