On Sun, Aug 11, 2019 at 12:15:08PM -0400, Theodore Y. Ts'o wrote:

quoted

Nak.  No weird fs specific fiemap flags that aren't even in the uapi
header.  Please provide your own debug only interface.

I can understand why you don't like this from the principle of the
thing.

I think mixing up in-kernel temporary state with the on-disk layout
is a bad idea, yes.  I think it is an even worse idea to try to sneak
it in without API review in an undocumented fashion.

I'll create my own ioctl, and make a copy of ioctl_fiemap() into ext4
and modify it for my needs.  I was trying to avoid needing to do that,
since there is plenty of space in the fiemap flags to carve out space
for file-specific specific flags, and avoiding making extra copies of
code for the purposes of reuse weighed more heavily than "no
fs-specific fiemap flags".

I think dumping your internal state is a candidate for debugs, not
a copy of ioctl_fiemap.