diff options
Diffstat (limited to 'include/linux/blk-cgroup.h')
| -rw-r--r-- | include/linux/blk-cgroup.h | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index 6c666fd7de3c..69aa71dc0c04 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -239,6 +239,22 @@ static inline struct blkcg *bio_blkcg(struct bio *bio) } /** + * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg + * @return: true if this bio needs to be submitted with the root blkg context. + * + * In order to avoid priority inversions we sometimes need to issue a bio as if + * it were attached to the root blkg, and then backcharge to the actual owning + * blkg. The idea is we do bio_blkcg() to look up the actual context for the + * bio and attach the appropriate blkg to the bio. Then we call this helper and + * if it is true run with the root blkg for that queue and then do any + * backcharging to the originating cgroup once the io is complete. + */ +static inline bool bio_issue_as_root_blkg(struct bio *bio) +{ + return (bio->bi_opf & REQ_META); +} + +/** * blkcg_parent - get the parent of a blkcg * @blkcg: blkcg of interest * |