On 7/20/21 1:43 AM, Darrick J. Wong wrote:

On Mon, Jul 19, 2021 at 10:38:34AM +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>
---
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?

Yes, but fa->fsx_xflags inherited from fa->flags (at least in ext4 it
is) is the original flags/xflags of the file before SETFLAG/FSSETXATTR.
Here we want to check *new* flags/xflags.

quoted

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

-- 
Thanks,
Jeffle