linux-ext4 - Re: [PATCH 3/9] fs/ext4: Disallow encryption if inode is DAX

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Date:   Mon, 18 May 2020 12:44:31 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     Ira Weiny <ira.weiny@...el.com>
Cc:     linux-ext4@...r.kernel.org,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        "Theodore Y. Ts'o" <tytso@....edu>, Jan Kara <jack@...e.cz>,
        Al Viro <viro@...iv.linux.org.uk>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Chinner <david@...morbit.com>,
        Christoph Hellwig <hch@....de>, Jeff Moyer <jmoyer@...hat.com>,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/9] fs/ext4: Disallow encryption if inode is DAX

On Mon, May 18, 2020 at 12:23:57PM -0700, Ira Weiny wrote:
> > 
> > The other question is what should happen when a file is created in an encrypted
> > directory when the filesystem is mounted with -o dax.  Actually, I think I
> > missed something there.  Currently (based on reading the code) the DAX flag will
> > get set first, and then ext4_set_context()
> 
> See this is where I am confused.  Above you said that ext4_set_context() is only
> called on a directory.  And I agree with you now having seen the check in
> fscrypt_ioctl_set_policy().  So what is the call path you are speaking of here?

Here's what I actually said:

	ext4_set_context() is only called when FS_IOC_SET_ENCRYPTION_POLICY sets
	an encryption policy on an empty directory, *or* when a new inode
	(regular, dir, or symlink) is created in an encrypted directory (thus
	inheriting encryption from its parent).

Just find the places where ->set_context() is called and follow them backwards.

- Eric