1. 13 Dec, 2018 38 commits
  2. 08 Dec, 2018 2 commits
    • Greg Kroah-Hartman's avatar
      Linux 4.19.8 · 178574b6
      Greg Kroah-Hartman authored
      178574b6
    • Jens Axboe's avatar
      blk-mq: punt failed direct issue to dispatch list · 55cbeea7
      Jens Axboe authored
      commit c616cbee upstream.
      
      After the direct dispatch corruption fix, we permanently disallow direct
      dispatch of non read/write requests. This works fine off the normal IO
      path, as they will be retried like any other failed direct dispatch
      request. But for the blk_insert_cloned_request() that only DM uses to
      bypass the bottom level scheduler, we always first attempt direct
      dispatch. For some types of requests, that's now a permanent failure,
      and no amount of retrying will make that succeed. This results in a
      livelock.
      
      Instead of making special cases for what we can direct issue, and now
      having to deal with DM solving the livelock while still retaining a BUSY
      condition feedback loop, always just add a request that has been through
      ->queue_rq() to the hardware queue dispatch list. These are safe to use
      as no merging can take place there. Additionally, if requests do have
      prepped data from drivers, we aren't dependent on them not sharing space
      in the request structure to safely add them to the IO scheduler lists.
      
      This basically reverts ffe81d45 and is based on a patch from Ming,
      but with the list insert case covered as well.
      
      Fixes: ffe81d45 ("blk-mq: fix corruption with direct issue")
      Cc: stable@vger.kernel.org
      Suggested-by: default avatarMing Lei <ming.lei@redhat.com>
      Reported-by: default avatarBart Van Assche <bvanassche@acm.org>
      Tested-by: default avatarMing Lei <ming.lei@redhat.com>
      Acked-by: default avatarMike Snitzer <snitzer@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      55cbeea7