[PATCH 1/3] block: Fix sysfs queue freeze and limits lock order

[Christoph Hellwig]

Did you find an exploit on my development laptop to find what I'm
working on? :)

I've got the same patch sitting here locally together with a few other
cleanups from before the holidays.  But the problem I rant into and
why I didn't finish it, is that is that the lock order doesn't work
for __blk_mq_update_nr_hw_queues which freezes at a very high level
and then does a queue limits update.  Now the whole changing of the
poll flag there look a bit questionable anyway and I was going to
look into how we could fix this, probably by retiring that flag either
just for blk-mq devices where the information can be derived from the
tagset or entirely.  I'll try to get to it ASAP.