On Mon, Mar 8, 2021 at 12:17 PM Chengguang Xu <cgxu519@xxxxxxxxxxxx> wrote: > > Currently copy-up will copy whole lower file to upper > regardless of the data range which is needed for further > operation. This patch avoids unnecessary copy when truncate > size is smaller than the file size. This doesn't look right. If copy up succeeds, resulting in a truncated file, then we should return success there and then. Doing the truncate again and failing (unlikely, but I wouldn't think it impossible) wouldn't be nice. But need to be careful, because we could possibly have other attribute change requests besides ATTR_SIZE, in which case optimizing the truncate away and returning success wouldn't be correct. Minor issue: this patch doesn't optimize the truncate to zero case. That's not a bug, but I'm curious if that is an oversight or deliberate. Thanks, Miklos
