On 3/4/20 12:03 PM, Josh Triplett wrote: > On Wed, Mar 04, 2020 at 11:00:10AM -0700, Jens Axboe wrote: >> One of the fabled features with chains has long been the desire to >> support things like: >> >> <open fileX><read from fileX><close fileX> >> >> in a single chain. This currently doesn't work, since the read/close >> depends on what file descriptor we get on open. >> >> The original attempt at solving this provided a means to pass >> descriptors between chains in a link, this version takes a different >> route. Based on Josh's support for O_SPECIFIC_FD, we can instead control >> what fd value we're going to get out of open (or accept). With that in >> place, we don't need to do any magic to make this work. The above chain >> then becomes: >> >> <open fileX with fd Y><read from fd Y><close fd Y> >> >> which is a lot more useful, and allows any sort of weird chains without >> needing to nest "last open" file descriptors. >> >> Updated the test program to use this approach: >> >> https://git.kernel.dk/cgit/liburing/plain/test/orc.c?h=fd-select >> >> which forces the use of fd==89 for the open, and then uses that for the >> read and close. >> >> Outside of this adaptation, fixed a few bugs and cleaned things up. > > I posted one comment about an issue in patch 6. > > Patches 2-5 look great; for those: > Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx> > > Thanks for picking this up and running with it! Thanks for doing the prep work! I think it turned out that much better for it. Are you going to post your series for general review? I just stole your 1 patch that was needed for me. -- Jens Axboe
