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Commit 786dc86c authored by Mike Snitzer's avatar Mike Snitzer Committed by Greg Kroah-Hartman
Browse files

dm: interlock pending dm_io and dm_wait_for_bios_completion 



commit 9f6dc633761006f974701d4c88da71ab68670749 upstream.

Commit d208b89401e0 ("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: d208b89401e0 ("dm: fix mempool NULL pointer race when completing IO")
Cc: stable@vger.kernel.org
Co-developed-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Reviewed-by: default avatarMike Snitzer <snitzer@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ad1393b9

drivers/md/dm.c

+7 −3
Original line number Original line Diff line number Diff line
@@ -681,14 +681,16 @@ static void end_io_acct(struct mapped_device *md, struct bio *bio, 
{

{

	unsigned long duration = jiffies - start_time;

	unsigned long duration = jiffies - start_time;





	generic_end_io_acct(md->queue, bio_op(bio), &dm_disk(md)->part0,

			    start_time);



	if (unlikely(dm_stats_used(&md->stats)))

	if (unlikely(dm_stats_used(&md->stats)))

		dm_stats_account_io(&md->stats, bio_data_dir(bio),

		dm_stats_account_io(&md->stats, bio_data_dir(bio),

				    bio->bi_iter.bi_sector, bio_sectors(bio),

				    bio->bi_iter.bi_sector, bio_sectors(bio),

				    true, duration, stats_aux);

				    true, duration, stats_aux);





	smp_wmb();



	generic_end_io_acct(md->queue, bio_op(bio), &dm_disk(md)->part0,

			    start_time);



	/* nudge anyone waiting on suspend queue */

	/* nudge anyone waiting on suspend queue */

	if (unlikely(wq_has_sleeper(&md->wait)))

	if (unlikely(wq_has_sleeper(&md->wait)))

		wake_up(&md->wait);

		wake_up(&md->wait);
@@ -2494,6 +2496,8 @@ static int dm_wait_for_completion(struct mapped_device *md, long task_state) 
	}

	}

	finish_wait(&md->wait, &wait);

	finish_wait(&md->wait, &wait);





	smp_rmb();



	return r;

	return r;

}

}