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dm: interlock pending dm_io and dm_wait_for_bios_completion
commit9f6dc63376
upstream. Commitd208b89401
("dm: fix mempool NULL pointer race when completing IO") didn't go far enough. When bio_end_io_acct ends the count of in-flight I/Os may reach zero and the DM device may be suspended. There is a possibility that the suspend races with dm_stats_account_io. Fix this by adding percpu "pending_io" counters to track outstanding dm_io. Move kicking of suspend queue to dm_io_dec_pending(). Also, rename md_in_flight_bios() to dm_in_flight_bios() and update it to iterate all pending_io counters. Fixes:d208b89401
("dm: fix mempool NULL pointer race when completing IO") Cc: stable@vger.kernel.org Co-developed-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Mike Snitzer <snitzer@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -2230,6 +2230,8 @@ static int dm_wait_for_completion(struct mapped_device *md, long task_state)
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}
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}
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finish_wait(&md->wait, &wait);
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finish_wait(&md->wait, &wait);
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smp_rmb(); /* paired with atomic_dec_return in end_io_acct */
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return r;
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return r;
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}
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}
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