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

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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>
This commit is contained in:
Xiao Ni 2018-08-30 15:57:09 +08:00 committed by Shaohua Li
parent e254de6bcf
commit 1d0ffd2642
1 changed files with 4 additions and 1 deletions
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5
drivers/md/raid10.c
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@ -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
*/