Re: [PATCH V1 2/9] fs/ext4: Disallow verity if inode is DAX

Jan Kara
2020-05-14T10:22:44Z

On Wed 13-05-20 23:53:08, ira.weiny@intel.com wrote:
> 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>

Makes sence. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

>
> ---
> Changes:
> remove WARN_ON_ONCE
> Add documentation for DAX/Verity exclusivity
> ---
> Documentation/filesystems/ext4/verity.rst | 7 +++++++
> fs/ext4/verity.c | 3 +++
> 2 files changed, 10 insertions(+)
>
> diff --git a/Documentation/filesystems/ext4/verity.rst b/Documentation/filesystems/ext4/verity.rst
> index 3e4c0ee0e068..51ab1aa17e59 100644
> --- a/Documentation/filesystems/ext4/verity.rst
> +++ b/Documentation/filesystems/ext4/verity.rst
> @@ -39,3 +39,10 @@ is encrypted as well as the data itself.
>
> Verity files cannot have blocks allocated past the end of the verity
> metadata.
> +
> +Verity and DAX
> +--------------
> +
> +Verity and DAX are not compatible and attempts to set both of these flags on a
> +file will fail.
> +
> diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c
> index dc5ec724d889..f05a09fb2ae4 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 (IS_DAX(inode))
> + return -EINVAL;
> +
> if (ext4_verity_in_progress(inode))
> return -EBUSY;
>
> --
> 2.25.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR