Re: [PATCH RFC 3/8] fs/ext4: Disallow encryption if inode is DAX

Jan Kara
2020-04-15T12:08:33Z

On Mon 13-04-20 21:00:25, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
>
> Encryption and DAX are incompatible. Changing the DAX mode due to a
> change in Encryption mode is wrong without a corresponding
> address_space_operations update.
>
> Make the 2 options mutually exclusive by returning an error if DAX was
> set first.
>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> ---
> fs/ext4/super.c | 10 +---------
> 1 file changed, 1 insertion(+), 9 deletions(-)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 0c7c4adb664e..b14863058115 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1325,7 +1325,7 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
> if (inode->i_ino == EXT4_ROOT_INO)
> return -EPERM;
>
> - if (WARN_ON_ONCE(IS_DAX(inode) && i_size_read(inode)))
> + if (WARN_ON_ONCE(IS_DAX(inode)))

Also here I don't think WARN_ON_ONCE() is warranted once we allow per-inode
setting of DAX. It will then become a regular error condition...

Honza

> return -EINVAL;
>
> res = ext4_convert_inline_data(inode);
> @@ -1349,10 +1349,6 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
> ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
> ext4_clear_inode_state(inode,
> EXT4_STATE_MAY_INLINE_DATA);
> - /*
> - * Update inode->i_flags - S_ENCRYPTED will be enabled,
> - * S_DAX may be disabled
> - */
> ext4_set_inode_flags(inode);
> }
> return res;
> @@ -1376,10 +1372,6 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
> ctx, len, 0);
> if (!res) {
> ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
> - /*
> - * Update inode->i_flags - S_ENCRYPTED will be enabled,
> - * S_DAX may be disabled
> - */
> ext4_set_inode_flags(inode);
> res = ext4_mark_inode_dirty(handle, inode);
> if (res)
> --
> 2.25.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR