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

On 7/17/21 12:20 AM, Darrick J. Wong wrote:

On Fri, Jul 16, 2021 at 02:19:51PM +0800, Jeffle Xu wrote:

quoted

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