block: fix bug in ptbl lookup cache
Neil writes:
Hi Jens,
I've found a little bug for you. It was introduced by
a6f23657d3072bde6844055bbc2290e497f33fbc
block: add one-hit cache for disk partition lookup
and has the effect of killing my machine whenever I try to assemble
an md array :-(
One of the devices in the array has partitions, and mdadm always
deletes partitions before putting a whole-device in an array (as it
can cause confusion). The next IO to that device locks the machine.
I don't really understand exactly why it locks up, but it happens in
disk_map_sector_rcu(). This patch fixes it.
Which is due to a missing clear of the (now) stale partition lookup
data. So clear that when we delete a partition.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 5198ada..6d72024 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -334,6 +334,7 @@
blk_free_devt(part_devt(part));
rcu_assign_pointer(ptbl->part[partno], NULL);
+ rcu_assign_pointer(ptbl->last_lookup, NULL);
kobject_put(part->holder_dir);
device_del(part_to_dev(part));