[PATCH 3/3] xstat: Implement a requestable extra result to procure some inode flags [ver #4]

[David Howells]

Andreas Dilger <adilger at dilger.ca> wrote:

> I would say this should be a full-fledged member of struct xstat.  I think
> they are fairly standard (available on many filesystems today), and
> requiring an ioctl to access them is unpleasant.

Remember: adding them to xstat and kstat will use up three extra 64-bit words
of stack at least if ecryptfs.

Are they used often enough to justify this?

> Yuck on the names.  Why not stick with the "UF_" and "SF_" prefixes?

Firstly, this is a quick and dirty example, primarily because I'd like someone
to take a look at the mechanism.

Secondly, because the flags I've added don't have UF_ and SF_ variants within
Linux.

> Since we don't need to keep _binary_ compatibility with these flag values
> (only name portability) we can use the same flag values as the FS_*_FL
> definitions in fs.h.

No, you can't, because Linux doesn't have separate S and U variants.

However, I'd be quite happy to just use the FS_*_FL, perhaps plus a couple of
flags, and have userspace munge together the BSD-compatible st_flags.  To that
end, could we rearrange i_flags to match the ioctl?

David