I recently sent a patch for 32-bit project IDs for xfsdump, to properly
restore the top 16 bits, which otherwise get lost. This forced a new
dump format version 4 (we were currently at 3).
One thing missing is that we should not restore a dump with 32-bit
project IDs onto a filesystem w/o that format; the restore will fail
to restore the top 16 bits (but otherwise it returns success; attribute
setting failures are not fatal (!?))
Also, 32-bit project ID is a bit uncommon; bumping the format (and making
older restore incompatible) is a bit draconian.
3 patches here:
1/3: extend fs info call to get fs flags as well
2/3: default back to V3 and go to V4 only if the projid32 flag is set
3/3: fail restore if the target XFS fs doesn't have projid32 set
I have to say, I'm not super happy with this. I have nagging fear
of feature-flag-itis, and I'm not sure how extensible this is as newer
versions may appear. But anyway, here's a place to start.
(p.s. anybody have wkendall's new email?) ;)