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From:   ira.weiny@intel.com
To:     linux-kernel@vger.kernel.org, Jan Kara <jack@suse.cz>
Cc:     Ira Weiny <ira.weiny@intel.com>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Chinner <david@fromorbit.com>,
        Christoph Hellwig <hch@lst.de>,
        "Theodore Y. Ts'o" <tytso@mit.edu>, Jeff Moyer <jmoyer@redhat.com>,
        linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
Subject: [PATCH RFC 2/8] fs/ext4: Disallow verity if inode is DAX
Date:   Mon, 13 Apr 2020 21:00:24 -0700
Message-Id: <20200414040030.1802884-3-ira.weiny@intel.com>
In-Reply-To: <20200414040030.1802884-1-ira.weiny@intel.com>
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From: Ira Weiny <ira.weiny@intel.com>

Verity and DAX are incompatible.  Changing the DAX mode due to a verity
flag change is wrong without a corresponding address_space_operations
update.

Make the 2 options mutually exclusive by returning an error if DAX was
set first.

(Setting DAX is already disabled if Verity is set first.)

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
 fs/ext4/verity.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c
index dc5ec724d889..ce3f9a198d3b 100644
--- a/fs/ext4/verity.c
+++ b/fs/ext4/verity.c
@@ -113,6 +113,9 @@ static int ext4_begin_enable_verity(struct file *filp)
 	handle_t *handle;
 	int err;
 
+	if (WARN_ON_ONCE(IS_DAX(inode)))
+		return -EINVAL;
+
 	if (ext4_verity_in_progress(inode))
 		return -EBUSY;
 
-- 
2.25.1