Re: UAPI value collision: STATX_ATTR_MOUNT_ROOT vs STATX_ATTR_DAX

[Miklos Szeredi]

On Wed, Nov 25, 2020 at 5:57 PM David Howells <dhowells@xxxxxxxxxx> wrote:
>
> Hi Linus, Miklos, Ira,
>
> It seems that two patches that got merged in the 5.8 merge window collided and
> no one noticed until now:
>
> 80340fe3605c0 (Miklos Szeredi     2020-05-14 184) #define STATX_ATTR_MOUNT_ROOT         0x00002000 /* Root of a mount */
> ...
> 712b2698e4c02 (Ira Weiny          2020-04-30 186) #define STATX_ATTR_DAX                        0x00002000 /* [I] File is DAX */
>
> The question is, what do we do about it?  Renumber one or both of the
> constants?

<uapi/linux/stat.h>:
 * Note that the flags marked [I] correspond to generic FS_IOC_FLAGS
 * semantically.  Where possible, the numerical value is picked to correspond
 * also.

<uapi/linux/fs.h>:
#define FS_DAX_FL 0x02000000 /* Inode is DAX */

The DAX one can be the same value as FS_DAX_FL, the placement (after
STATX_ATTR_VERITY, instead of before) seems to confirm this intention.

Not that I care too much, the important thing is to have distinct values.
Thanks,
Miklos