1. 11 Nov, 2017 35 commits
  2. 07 Nov, 2017 2 commits
  3. 06 Nov, 2017 2 commits
  4. 04 Nov, 2017 1 commit
    • Ming Lei's avatar
      blk-mq: don't allocate driver tag upfront for flush rq · 923218f6
      Ming Lei authored
      The idea behind it is simple:
      
      1) for none scheduler, driver tag has to be borrowed for flush rq,
         otherwise we may run out of tag, and that causes an IO hang. And
         get/put driver tag is actually noop for none, so reordering tags
         isn't necessary at all.
      
      2) for a real I/O scheduler, we need not allocate a driver tag upfront
         for flush rq. It works just fine to follow the same approach as
         normal requests: allocate driver tag for each rq just before calling
         ->queue_rq().
      
      One driver visible change is that the driver tag isn't shared in the
      flush request sequence. That won't be a problem, since we always do that
      in legacy path.
      
      Then flush rq need not be treated specially wrt. get/put driver tag.
      This cleans up the code - for instance, reorder_tags_to_front() can be
      removed, and we needn't worry about request ordering in dispatch list
      for avoiding I/O deadlock.
      
      Also we have to put the driver tag before requeueing.
      Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      923218f6