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From: Ira Weiny <ira.weiny@intel.com>
To: "Theodore Y. Ts'o" <tytso@mit.edu>
Cc: linux-kernel@vger.kernel.org, Jan Kara <jack@suse.cz>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@lst.de>, Jeff Moyer <jmoyer@redhat.com>,
	linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH RFC 3/8] fs/ext4: Disallow encryption if inode is DAX
Date: Tue, 21 Apr 2020 11:41:43 -0700	[thread overview]
Message-ID: <20200421184143.GA3004764@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20200415195433.GC2305801@iweiny-DESK2.sc.intel.com>

On Wed, Apr 15, 2020 at 12:54:34PM -0700, 'Ira Weiny' wrote:
> On Wed, Apr 15, 2020 at 12:03:07PM -0400, Theodore Y. Ts'o wrote:
> > On Mon, Apr 13, 2020 at 09:00:25PM -0700, ira.weiny@intel.com wrote:
 
[snip]

> > 
> > Also note that encrypted files are read/write so we must never allow
> > the combination of ENCRPYT_FL and DAX_FL.  So that may be something
> > where we should teach __ext4_iget() to check for this, and declare the
> > file system as corrupted if it sees this combination.
> 
> ok...

After thinking about this...

Do we really want to declare the FS corrupted?

If so, I think we need to return errors when such a configuration is attempted.
If in the future we have an encrypted mode which can co-exist with DAX (such as
Dan mentioned) we can change this.

FWIW I think we should return errors when such a configuration is attempted but
_not_ declare the FS corrupted.  That allows users to enable this configuration
later if we can figure out how to support it.

> 
> > (For VERITY_FL
> > && DAX_FL that is a combo that we might want to support in the future,
> > so that's probably a case where arguably, we should just ignore the
> > DAX_FL for now.)
> 
> ok...

I think this should work the same.

It looks like VERITY_FL and ENCRYPT_FL are _not_ user modifiable?  Is that
correct?

You said that ENCRPYT_FL is set from the parent directory?  But I'm not seeing
where that occurs?

Similarly I don't see where VERITY_FL is being set either?  :-/

I think to make this work correctly we should restrict setting those flags if
DAX_FL is set and vice versa.  But I'm not finding where to do that.  :-/

Ira

> 
> Ira
> 

  reply	other threads:[~2020-04-21 18:41 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-14  4:00 [PATCH RFC 0/8] Enable ext4 support for per-file/directory DAX operations ira.weiny
2020-04-14  4:00 ` [PATCH RFC 1/8] fs/ext4: Narrow scope of DAX check in setflags ira.weiny
2020-04-15 11:45   ` Jan Kara
2020-04-14  4:00 ` [PATCH RFC 2/8] fs/ext4: Disallow verity if inode is DAX ira.weiny
2020-04-15 11:58   ` Jan Kara
2020-04-15 12:00   ` Jan Kara
2020-04-15 15:55     ` Theodore Y. Ts'o
2020-04-15 19:21       ` Ira Weiny
2020-04-15 19:14     ` Ira Weiny
2020-04-16  1:29       ` Eric Biggers
2020-04-16  3:48         ` Ira Weiny
2020-04-15 20:34     ` Ira Weiny
2020-04-14  4:00 ` [PATCH RFC 3/8] fs/ext4: Disallow encryption " ira.weiny
2020-04-15 12:02   ` Jan Kara
2020-04-15 20:35     ` Ira Weiny
2020-04-15 16:03   ` Theodore Y. Ts'o
2020-04-15 17:27     ` Dan Williams
2020-04-15 19:54     ` Ira Weiny
2020-04-21 18:41       ` Ira Weiny [this message]
2020-04-21 18:56         ` Darrick J. Wong
2020-04-14  4:00 ` [PATCH RFC 4/8] fs/ext4: Introduce DAX inode flag ira.weiny
2020-04-15 12:08   ` Jan Kara
2020-04-15 20:39     ` Ira Weiny
2020-04-16 10:32       ` Jan Kara
2020-04-16 18:01       ` Theodore Y. Ts'o
2020-04-16 16:25   ` Darrick J. Wong
2020-04-16 22:33     ` Ira Weiny
2020-04-16 22:49       ` Darrick J. Wong
2020-04-17  0:37         ` Ira Weiny
2020-04-17  1:57           ` Darrick J. Wong
2020-04-17  2:20             ` Ira Weiny
2020-04-17  6:43               ` Andreas Dilger
2020-04-17 17:19                 ` Ira Weiny
2020-04-14  4:00 ` [PATCH RFC 5/8] fs/ext4: Make DAX mount option a tri-state ira.weiny
2020-04-15 12:51   ` Jan Kara
2020-04-14  4:00 ` [PATCH RFC 6/8] fs/ext4: Update ext4_should_use_dax() ira.weiny
2020-04-15 13:58   ` Jan Kara
2020-04-17 17:16     ` Ira Weiny
2020-04-14  4:00 ` [PATCH RFC 7/8] fs/ext4: Only change S_DAX on inode load ira.weiny
2020-04-15 14:03   ` Jan Kara
2020-04-17 17:18     ` Ira Weiny
2020-04-14  4:00 ` [PATCH RFC 8/8] Documentation/dax: Update DAX enablement for ext4 ira.weiny

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