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Subject: Re: [PATCH] vfs: only allow SETFLAGS to set DAX flag on files and
 dirs
To:     "Darrick J. Wong" <djwong@kernel.org>
Cc:     viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org,
        linux-ext4@vger.kernel.org
References: <20210716061951.81529-1-jefflexu@linux.alibaba.com>
 <20210716162017.GA22346@magnolia>
From:   JeffleXu <jefflexu@linux.alibaba.com>
Message-ID: <e85ceae6-23b8-aea8-1314-7e2ebece61d6@linux.alibaba.com>
Date:   Mon, 19 Jul 2021 09:47:45 +0800
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On 7/17/21 12:20 AM, Darrick J. Wong wrote:
> On Fri, Jul 16, 2021 at 02:19:51PM +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@linux.alibaba.com>
>> ---
>>  fs/ioctl.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/ioctl.c b/fs/ioctl.c
>> index 1e2204fa9963..1fe73e148e2d 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) &&
> 
> I thought we always had to surround flag tests with separate
> parentheses...?

Thanks.

The 'bitwise and' has a higher priority than 'logical or'. But for sure
I can add parentheses to make it more readable and precise.

-- 
Thanks,
Jeffle