linux-ext4 - Re: [PATCH v2] vfs: only allow SETFLAGS to set DAX flag on files and dirs

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Date:   Mon, 19 Jul 2021 10:43:31 -0700
From:   "Darrick J. Wong" <djwong@...nel.org>
To:     Jeffle Xu <jefflexu@...ux.alibaba.com>
Cc:     viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org,
        linux-ext4@...r.kernel.org
Subject: Re: [PATCH v2] vfs: only allow SETFLAGS to set DAX flag on files and
 dirs

On Mon, Jul 19, 2021 at 10:38:34AM +0800, Jeffle Xu wrote:
> This is similar to commit dbc77f31e58b ("vfs: only allow FSSETXATTR to
> set DAX flag on files and dirs").
> 
> Though the underlying filesystems may have filtered invalid flags, e.g.,
> ext4_mask_flags() called in ext4_fileattr_set(), also check it in VFS
> layer.
> 
> Signed-off-by: Jeffle Xu <jefflexu@...ux.alibaba.com>
> ---
> changes since v1:
> - add separate parentheses surrounding flag tests
> ---
>  fs/ioctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ioctl.c b/fs/ioctl.c
> index 1e2204fa9963..90cfaa4db03a 100644
> --- a/fs/ioctl.c
> +++ b/fs/ioctl.c
> @@ -835,7 +835,7 @@ static int fileattr_set_prepare(struct inode *inode,
>  	 * It is only valid to set the DAX flag on regular files and
>  	 * directories on filesystems.
>  	 */
> -	if ((fa->fsx_xflags & FS_XFLAG_DAX) &&
> +	if (((fa->fsx_xflags & FS_XFLAG_DAX) || (fa->flags & FS_DAX_FL)) &&

Isn't fileattr_fill_flags supposed to fill out fa->fsx_xflags from
fa->flags for a SETFLAGS call?

--D

>  	    !(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
>  		return -EINVAL;
>  
> -- 
> 2.27.0
>