diff options
Diffstat (limited to 'block/blk-mq.h')
| -rw-r--r-- | block/blk-mq.h | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/block/blk-mq.h b/block/blk-mq.h index f4bf5161333e..32c62c64e6c2 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -233,4 +233,36 @@ static inline void blk_mq_clear_mq_map(struct blk_mq_queue_map *qmap) qmap->mq_map[cpu] = 0; } +/* + * blk_mq_plug() - Get caller context plug + * @q: request queue + * @bio : the bio being submitted by the caller context + * + * Plugging, by design, may delay the insertion of BIOs into the elevator in + * order to increase BIO merging opportunities. This however can cause BIO + * insertion order to change from the order in which submit_bio() is being + * executed in the case of multiple contexts concurrently issuing BIOs to a + * device, even if these context are synchronized to tightly control BIO issuing + * order. While this is not a problem with regular block devices, this ordering + * change can cause write BIO failures with zoned block devices as these + * require sequential write patterns to zones. Prevent this from happening by + * ignoring the plug state of a BIO issuing context if the target request queue + * is for a zoned block device and the BIO to plug is a write operation. + * + * Return current->plug if the bio can be plugged and NULL otherwise + */ +static inline struct blk_plug *blk_mq_plug(struct request_queue *q, + struct bio *bio) +{ + /* + * For regular block devices or read operations, use the context plug + * which may be NULL if blk_start_plug() was not executed. + */ + if (!blk_queue_is_zoned(q) || !op_is_write(bio_op(bio))) + return current->plug; + + /* Zoned block device write operation case: do not plug the BIO */ + return NULL; +} + #endif |