On 11/01/2021 09:35, David Laight wrote: > From: Pavel Begunkov >> Sent: 09 January 2021 22:11 > .... >>> Does any code actually look at the fields as a pair? >>> Would it even be better to use separate bytes? >>> Even growing the on-stack structure by a word won't really matter. >> >> u8 type, rw; >> >> That won't bloat the struct. I like the idea. If used together compilers >> can treat it as u16. >> >> btw there is a 4B hole just after for x64. > > I've just had a quick look at the sources. > (Nothing was powered up earlier.) > > AFAICT nothing needs the RW flag to be in the same word > as the type. > If you think about it, the call site is specific to read/write. > The only places iov_iter_rw() is used in inside helper functions > to save the direction being passed from the caller. > > I hope the comment about bit 1 being BVEC_FLAG_NO_REF is old. > I can't find any references to that flag. Yep, long dead. -- Pavel Begunkov
