On Fri, Jun 18, 2021 at 07:49:53PM +0000, Al Viro wrote: > On Fri, Jun 18, 2021 at 07:42:41PM +0000, Al Viro wrote: > > > Pipe ones are strictly destinations - they can't be sources. So if you > > see it called for one of those, you've a bug. > > > > Xarray ones are *not* - they can be sources, and that's missing here. > > > > Much more unpleasant, though, is that this thing has hard dependency on > > nr_seg == 1 *AND* openly suggests the use of iov_iter_single_seg_count(), > > which is completely wrong. That sucker has some weird users left (as > > of #work.iov_iter), but all of them are actually due to API deficiencies > > and I very much hope to kill that thing off. > > > > Why not simply add iov_iter_check_zeroes(), that would be called after > > copy_from_iter() and verified that all that's left in the iterator > > consists of zeroes? Then this copy_struct_from_...() would be > > trivial to express through those two. And check_zeroes would also > > be trivial, especially on top of #work.iov_iter. With no calls of > > iov_iter_advance() at all, while we are at it... > > > > IDGI... Omar, what semantics do you really want from that primitive? > > And for pity sake, let's not do that EXPORT_SYMBOL_GPL() posturing there. > If it's a sane general-purpose API, it doesn't matter who uses it; > if it's not, it shouldn't be exported in the first place. > > It can be implemented via the already exported primitives, so it's > not as if we prevented anyone from doing an equivalent... Fair enough, I'll fix that.
