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

Ira Weiny
2020-04-15T20:36:09Z

On Wed, Apr 15, 2020 at 02:02:41PM +0200, Jan Kara wrote:
> 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...

Removed.
Ira

>
> 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