dm: fix inflight IO check
After switching to percpu inflight counters, the inflight check is totally buggy. It's perfectly valid for some counters to be non-zero while having a total inflight IO count of 0, that's how these kinds of counters work (inc on one CPU, dec on another). Fix the md_in_flight() check to sum all counters before returning a false positive, potentially. While at it, remove the inflight read for IO completion. We don't need it, just wake anyone that's waiting for the IO count to drop to zero. The caller needs to re-check that value anyway when woken, which it does. Fixes: 6f757231 ("dm: remove the pending IO accounting") Acked-by: Mike Snitzer <snitzer@redhat.com> Reported-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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