Re: [PATCH v2] loop: fix no-unmap write-zeroes request behavior

[Christoph Hellwig]

While this looks generally good to me, I have another nitpick to avoid
code duplication.  What about just renaming lo_discard to lo_fallocate
and pass the mode (possibly minus the FALLOC_FL_KEEP_SIZE flag) to it?

The in the do_req_filebacked we could further simplify it down to:

        case REQ_OP_WRITE_ZEROES:
                /*
                 * If the caller doesn't want deallocation, call zeroout to
                 * write zeroes the range.  Otherwise, punch them out.
                 */
                return lo_fallocate(lo, rq, pos,
                        (rq->cmd_flags & REQ_NOUNMAP) ?
                                FALLOC_FL_ZERO_RANGE : FALLOC_FL_PUNCH_HOLE);
                break;
        case REQ_OP_DISCARD:
                return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);