On Fri, May 07, 2021 at 12:29:44PM -0700, Linus Torvalds wrote: > On Fri, May 7, 2021 at 12:17 PM Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > > > Umm... That would do wonders to anything that used to do > > copy_to_user()/clear_user()/copy_to_user() and got converted > > to copy_to_iter()/iov_iter_zero()/copy_to_iter()... > > I didn't mean for iov_iter_zero doing this - only splice_read_zero(). > > > Are you sure we can shove zero page into pipe, anyway? > > IIRC, get_page()/put_page() on that is not allowed, > > That's what the > > buf->ops = &zero_pipe_buf_ops; > > is for. The zero_pipe_buf_ops would have empty get and release > functions, and a 'steal' function that always returns false. > > That's how the pipe pages are supposed to work: there are people who > put non-page data (ie things like skbuff allocations etc) into a > splice pipe buffer. It's why we have those "ops" pointers. Supposed to - sure, but I'd like to verify that they actually do work that way before we go there. Let me RTFS a bit...
