On Tue, Nov 23, 2021 at 02:44:32PM +0800, Qu Wenruo wrote: > Hi, > > Although there are some out-of-date comments mentions other > bio_clone_*() variants, but there isn't really any other bio clone > variants other than __bio_clone_fast(), which shares bi_io_vec with the > source bio. > > This limits means we can't free the source bio before the cloned one. > > Is there any bio_clone variant which do a deep clone, including bi_io_vec? There is no use case for that, unless the actual data changes like in the bounce buffering code. > That's why the bio_clone thing is involved, there is still some corner > cases that we don't want to fail the whole large bio if there is only > one stripe failed (mostly for read bio, that we want to salvage as much > data as possible) > > Thus regular bio_split() + bio_chain() solution is not that good here. > > Any idea why no such bio_clone_slow() or bio_split_slow() provided in > block layer? > > Or really bio_split() + bio_chain() is the only recommended solution? You can use bio_split witout bio_chain. You just need your own bi_end_io handler that first performs the action you want and then contains code equivalent to __bio_chain_endio. As a bonus you can pint bi_private to whatever you want, it does not have to be the parent bio, just something that allows you to find it.
