So, the whole scan for delalloc logic seems pretty generic, I think
it can an should be lifted to iomap, with
xfs_buffered_write_delalloc_punch provided as a callback.
As for the reuse of the seek hole / data helpers, and I'm not sure
this actually helps all that much, and certainly is not super
efficient. I don't want you to directly talk into rewriting this
once again, but a simple
while ((folio = find_get_entry(&xas, max, XA_PRESENT))) {
if (xa_is_value(folio) || folio_test_uptodate(folio) ||
ops->is_partially_uptodate) {
xas_pause(xas);
rcu_read_unlock();
folio_lock(folio);
if (likely(folio->mapping == mapping) &&
folio_test_dirty(folio)) {
// crop folio start / end by total range
if (ops->is_partially_uptodate) {
// find partial range
}
// add to or start new range
}
} else {
// pause rcu unlock and submit previous range if
// needed
}
// move to next folio with size magic etc
}
// submit pending range if it exists
