diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/bfq-iosched.c | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 02dd4c836936..aa32e56cb385 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -1839,15 +1839,28 @@ static void bfq_request_merged(struct request_queue *q, struct request *req, } } +/* + * This function is called to notify the scheduler that the requests + * rq and 'next' have been merged, with 'next' going away. BFQ + * exploits this hook to address the following issue: if 'next' has a + * fifo_time lower that rq, then the fifo_time of rq must be set to + * the value of 'next', to not forget the greater age of 'next'. + * Moreover 'next' may be in a bfq_queue, in this case it must be + * removed. + * + * NOTE: in this function we assume that rq is in a bfq_queue, basing + * on that rq is picked from the hash table q->elevator->hash, which, + * in its turn, is filled only with I/O requests present in + * bfq_queues, while BFQ is in use for the request queue q. In fact, + * the function that fills this hash table (elv_rqhash_add) is called + * only by bfq_insert_request. + */ static void bfq_requests_merged(struct request_queue *q, struct request *rq, struct request *next) { struct bfq_queue *bfqq = bfq_init_rq(rq), *next_bfqq = bfq_init_rq(next); - if (!RB_EMPTY_NODE(&rq->rb_node)) - goto end; - /* * If next and rq belong to the same bfq_queue and next is older * than rq, then reposition rq in the fifo (by substituting next @@ -1868,10 +1881,11 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq, if (bfqq->next_rq == next) bfqq->next_rq = rq; - bfq_remove_request(q, next); - bfqg_stats_update_io_remove(bfqq_group(bfqq), next->cmd_flags); + if (!RB_EMPTY_NODE(&next->rb_node)) { + bfq_remove_request(q, next); + bfqg_stats_update_io_remove(bfqq_group(bfqq), next->cmd_flags); + } -end: bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags); } |