block: fix stacked driver stats init and free
authorJens Axboe <axboe@fb.com>
Tue, 21 Mar 2017 23:20:01 +0000 (17:20 -0600)
committerJens Axboe <axboe@fb.com>
Tue, 21 Mar 2017 23:20:01 +0000 (17:20 -0600)
commita83b576c9c25cf771fb0b15ec5eb2e7510ec2f5a
treebaf705377f5e7a1d330eb0ece93f68e1aafe2161
parent34dbad5d26e2f4b88e60f0e9ad03f99480802812
block: fix stacked driver stats init and free

If a driver allocates a queue for stacked usage, then it does
not currently get stats allocated. This causes the later init
of, eg, writeback throttling to blow up. Move the init to the
queue allocation instead.

Additionally, allow a NULL callback unregistration. This avoids
having the caller check for that, fixing another oops on
removal of a block device that doesn't have poll stats allocated.

Fixes: 34dbad5d26e2 ("blk-stat: convert to callback-based statistics reporting")
Signed-off-by: Jens Axboe <axboe@fb.com>
block/blk-core.c
block/blk-stat.c