Merge branch 'block-5.7' into for-5.8/block

Pull in block-5.7 fixes for 5.8. Mostly to resolve a conflict with
the blk-iocost changes, but we also need the base of the bdi
use-after-free as well as we build on top of it.

* block-5.7:
  nvme: fix possible hang when ns scanning fails during error recovery
  nvme-pci: fix "slimmer CQ head update"
  bdi: add a ->dev_name field to struct backing_dev_info
  bdi: use bdi_dev_name() to get device name
  bdi: move bdi_dev_name out of line
  vboxsf: don't use the source name in the bdi name
  iocost: protect iocg->abs_vdebt with iocg->waitq.lock
  block: remove the bd_openers checks in blk_drop_partitions
  nvme: prevent double free in nvme_alloc_ns() error handling
  null_blk: Cleanup zoned device initialization
  null_blk: Fix zoned command handling
  block: remove unused header
  blk-iocost: Fix error on iocost_ioc_vrate_adj
  bdev: Reduce time holding bd_mutex in sync in blkdev_close()
  buffer: remove useless comment and WB_REASON_FREE_MORE_MEM, reason.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

tools/cgroup/iocost_monitor.py

@@ -160,7 +160,12 @@ class IocgStat:
         else:
             self.inflight_pct = 0
 
-        self.debt_ms = iocg.abs_vdebt.counter.value_() / VTIME_PER_USEC / 1000
+        # vdebt used to be an atomic64_t and is now u64, support both
+        try:
+            self.debt_ms = iocg.abs_vdebt.counter.value_() / VTIME_PER_USEC / 1000
+        except:
+            self.debt_ms = iocg.abs_vdebt.value_() / VTIME_PER_USEC / 1000
+
         self.use_delay = blkg.use_delay.counter.value_()
         self.delay_ms = blkg.delay_nsec.counter.value_() / 1_000_000