blkcg: convert blkg_lookup_create() to find closest blkg

There are several scenarios where blkg_lookup_create() can fail such as
the blkcg dying, request_queue is dying, or simply being OOM. Most
handle this by simply falling back to the q->root_blkg and calling it a
day.

This patch implements the notion of closest blkg. During
blkg_lookup_create(), if it fails to create, return the closest blkg
found or the q->root_blkg. blkg_try_get_closest() is introduced and used
during association so a bio is always attached to a blkg.

Signed-off-by: Dennis Zhou <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Reviewed-by: Josef Bacik <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions