Commit 1d0ffd26 authored Aug 30, 2018 by Xiao Ni Committed by Shaohua Li Aug 31, 2018

RAID10 BUG_ON in raise_barrier when force is true and conf->barrier is 0

In raid10 reshape_request it gets max_sectors in read_balance. If the underlayer disks
have bad blocks, the max_sectors is less than last. It will call goto read_more many
times. It calls raise_barrier(conf, sectors_done != 0) every time. In this condition
sectors_done is not 0. So the value passed to the argument force of raise_barrier is
true.

In raise_barrier it checks conf->barrier when force is true. If force is true and
conf->barrier is 0, it panic. In this case reshape_request submits bio to under layer
disks. And in the callback function of the bio it calls lower_barrier. If the bio
finishes before calling raise_barrier again, it can trigger the BUG_ON.

Add one pair of raise_barrier/lower_barrier to fix this bug.

Signed-off-by: Xiao Ni <xni@redhat.com>
Suggested-by: Neil Brown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

parent e254de6b

drivers/md/raid10.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -4529,11 +4529,12 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
		allow_barrier(conf);
		}

		raise_barrier(conf, 0);
		read_more:
		/* Now schedule reads for blocks from sector_nr to last */
		r10_bio = raid10_alloc_init_r10buf(conf);
		r10_bio->state = 0;
		raise_barrier(conf, sectors_done != 0);
		raise_barrier(conf, 1);
		atomic_set(&r10_bio->remaining, 0);
		r10_bio->mddev = mddev;
		r10_bio->sector = sector_nr;
		@@ -4629,6 +4630,8 @@ read_more:
		if (sector_nr <= last)
		goto read_more;

		lower_barrier(conf);

		/* Now that we have done the whole section we can
		* update reshape_progress
		*/

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