On Tue, Nov 21 2017 at 7:10am -0500, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > On Mon, Nov 20 2017 at 8:35pm -0500, > Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > > > On Mon, Nov 20 2017 at 7:34pm -0500, > > NeilBrown <neilb@xxxxxxxx> wrote: > > > > > Please see > > > https://www.redhat.com/archives/dm-devel/2017-August/msg00310.html > > I'll very likely pick these up for 4.16 shortly. But hope to work > through complete removal of DM's use of BIOSET_NEED_RESCUER for 4.16 as > well. > > > > and > > > https://www.redhat.com/archives/dm-devel/2017-August/msg00315.html > > This one [1] needs a lot of review and testing. Particularly against this > test case that Mikulas created to reproduce the snapshot deadlock (same > deadlock that motivated commit dbba42d8): > https://www.redhat.com/archives/dm-devel/2017-January/msg00064.html ... > Short of that, how would you like to proceed? > > > > That would then just leave bcache.... I find it a bit of a challenge to > > > reason about the code in bcache, but if we can remove > > > BIOSET_NEED_RESCUER from dm, that will be an extra incentive for me to learn :-) > > > > I'm all for properly removing BIOSET_NEED_RESCUER from DM. > > Should we work to make [1] (above) sure it fixes Mikulas' test case? > > I'll set in on reviewing and playing with [1] now. Decided it a better use of my time to review and then hopefully use the block-core's bio splitting infrastructure in DM. Been meaning to do that for quite a while anyway. This mail from you just made it all the more clear that needs doing: https://www.redhat.com/archives/dm-devel/2017-September/msg00098.html So I will start here on this patch you proposed: https://www.redhat.com/archives/dm-devel/2017-September/msg00091.html (of note, this patch slipped through the cracks because I was recovering from injury when it originally came through). Once DM is using q->bio_split I'll come back to this patch (aka "[1]") as a starting point for the follow-on work to remove DM's use of BIOSET_NEED_RESCUER: https://www.redhat.com/archives/dm-devel/2017-August/msg00315.html Mike
