The whole concept of "dtime" is _wrong_.
Reason: it implies you have to write out the inode after deleting it.
Which is just stupid, plain and simple - if we have deallocated the inode
it by definition no longer contains any useful information, so we
shouldn't spend time writing it out to disk.
When I wrote the minix filesystem I made certain that if I create a
temporary file it will result in the absolute minimal number of disk
writes. In fact, temporary files that were deleted quickly enough
generally resulted in only _one_ disk block being updated, and that was
the inode bitmap block (which usually becomes dirty anyway due to other
inode allocations - you seldom have just one temporary file).
I'm very touchy about latency issues, and dtime is a feature that is not
worth writing out the inode.
Linus