Over the last few weeks I've been working on other projects
(pretty must time dedicated to getting grep back into shape),
so coreutils has languished. Sorry for not giving more feedback,
but I have been watching.
In fact, seeing the use of HAVE_FTRUNCATE that is moved by your patch
is what prompted me to mark the ftruncate module as obsolete and remove
that code from copy.c.
While I'm writing, here's one high-level question for you.
When would your new --fiemap-sync option be useful, and what change
in semantics will I see between when I use it and when I don't?
--fiemap-sync sync file data before fiemap\n\
IMHO, there is no difference from the user's point of view with or without this
option.
and on the kernel side, if FIEMAP_FLAG_SYNC was specified, it just do the dirty
page process
regardless of the sync succeeds or failed due to ENOSPC or EIO or other errors.
I need to do more investigation to answer this question.