On Mon, Oct 22, 2012 at 03:24:16PM -0500, Eric Sandeen wrote: > commit 1e309da7a4f7e2a2f456bf6b7cea4c5f1181cd36 fixed xfsdump to > properly save & restore the top 16 bits of a 32-bit projid, which > otherwise was being dropped (and restored as 0) in older xfsdump. > > The original thought was to bump the dump version, so that we know > whether the dump (may) have the top 16 bits filled in. In practice > this would prevent older restores from restoring newer dumps, and > losing the top 16 bits contained in these newer dumps. > > However, in hindsight this appears to be of limited value. I > propose that the dump version change is unuseful/unwanted for a > couple reasons: > > * There is no actual dump *format* change; the structure size > is the same, and the top 16 bits were properly zeroed before; old > restores will read these fixed dumps without problems and without > restoring garbage. IOW, they will behave exactly as buggily as > they did before. And worst case, if a dump containing the top 16 > bits is mangled by an old restore, this can be easily remedied by > simply re-restoring with updated userspace. > > * We have no reliable method to know whether 32 bit project IDs are > in use; the feature flag was not added to the GEOM call at the time > of implementation. Therefore we cannot reliably bump to V4 only > for projid32bit filesystems, and we cannot restrict V4 restores > only to projid32bit filesystems. So the dump version is not > useful for feature cross-checking purposes. Seems reasonable. Definitely solves most of the nasty problems you've been juggling caused by a version bump and 32bit projid detection. Do we have an xfstest that verifies these assumptions are valid? Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
