Re: [man-pages RFC PATCH v4] statx, inode: document the new STATX_INO_VERSION field

J. Bruce Fields
2022-09-12T13:51:40Z

On Mon, Sep 12, 2022 at 08:55:04AM -0400, Jeff Layton wrote:
> Because of the "seen" flag, we have a 63 bit counter to play with. Could
> we use a similar scheme to the one we use to handle when "jiffies"
> wraps? Assume that we'd never compare two values that were more than
> 2^62 apart? We could add i_version_before/i_version_after macros to make
> it simple to handle this.

As far as I recall the protocol just assumes it can never wrap. I guess
you could add a new change_attr_type that works the way you describe.
But without some new protocol clients aren't going to know what to do
with a change attribute that wraps.

I think this just needs to be designed so that wrapping is impossible in
any realistic scenario. I feel like that's doable?

If we feel we have to catch that case, the only 100% correct behavior
would probably be to make the filesystem readonly.

--b.