cfq_find_alloc_queue() checks whether a queue actually needs to be allocated, which is unnecessary as its sole caller, cfq_get_queue(), only calls it if so. Also, the oom queue fallback logic is scattered between cfq_get_queue() and cfq_find_alloc_queue(). There really isn't much going on in the latter and things can be made simpler by folding it into cfq_get_queue().
This patch collapses cfq_find_alloc_queue() into cfq_get_queue(). The change is fairly straight-forward with one exception - async_cfqq is now initialized to NULL and the "!is_sync" test in the last if conditional is replaced with "async_cfqq" test. This is because gcc (5.1.1) gets confused for some reason and warns that async_cfqq may be used uninitialized otherwise. Oh well, the code isn't necessarily worse this way. This patch doesn't cause any functional difference. v2: Updated to reflect GFP_ATOMIC -> GPF_NOWAIT. Signed-off-by: Tejun Heo <t...@kernel.org> Reviewed-by: Jeff Moyer <jmo...@redhat.com> Cc: Vivek Goyal <vgo...@redhat.com> Cc: Arianna Avanzini <avanzini.aria...@gmail.com> --- block/cfq-iosched.c | 49 +++++++++++++++---------------------------------- 1 file changed, 15 insertions(+), 34 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index f3ea8a1..fa2a2f7 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3640,33 +3640,6 @@ static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { } #endif /* CONFIG_CFQ_GROUP_IOSCHED */ -static struct cfq_queue * -cfq_find_alloc_queue(struct cfq_data *cfqd, struct cfq_group *cfqg, bool is_sync, - struct cfq_io_cq *cic, struct bio *bio) -{ - struct cfq_queue *cfqq; - - cfqq = cic_to_cfqq(cic, is_sync); - - /* - * Always try a new alloc if we fell back to the OOM cfqq - * originally, since it should just be a temporary situation. - */ - if (!cfqq || cfqq == &cfqd->oom_cfqq) { - cfqq = kmem_cache_alloc_node(cfq_pool, - GFP_NOWAIT | __GFP_ZERO, - cfqd->queue->node); - if (cfqq) { - cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); - cfq_init_prio_data(cfqq, cic); - cfq_link_cfqq_cfqg(cfqq, cfqg); - cfq_log_cfqq(cfqd, cfqq, "alloced"); - } else - cfqq = &cfqd->oom_cfqq; - } - return cfqq; -} - static struct cfq_queue ** cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) { @@ -3691,7 +3664,7 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, { int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio); int ioprio = IOPRIO_PRIO_DATA(cic->ioprio); - struct cfq_queue **async_cfqq; + struct cfq_queue **async_cfqq = NULL; struct cfq_queue *cfqq; struct cfq_group *cfqg; @@ -3714,12 +3687,20 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, goto out; } - cfqq = cfq_find_alloc_queue(cfqd, cfqg, is_sync, cic, bio); + cfqq = kmem_cache_alloc_node(cfq_pool, GFP_NOWAIT | __GFP_ZERO, + cfqd->queue->node); + if (!cfqq) { + cfqq = &cfqd->oom_cfqq; + goto out; + } + + cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); + cfq_init_prio_data(cfqq, cic); + cfq_link_cfqq_cfqg(cfqq, cfqg); + cfq_log_cfqq(cfqd, cfqq, "alloced"); - /* - * pin the queue now that it's allocated, scheduler exit will prune it - */ - if (!is_sync && cfqq != &cfqd->oom_cfqq) { + if (async_cfqq) { + /* a new async queue is created, pin and remember */ cfqq->ref++; *async_cfqq = cfqq; } @@ -4469,7 +4450,7 @@ static int cfq_init_queue(struct request_queue *q, struct elevator_type *e) cfqd->prio_trees[i] = RB_ROOT; /* - * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. + * Our fallback cfqq if cfq_get_queue() runs into OOM issues. * Grab a permanent reference to it, so that the normal code flow * will not attempt to free it. oom_cfqq is linked to root_group * but shouldn't hold a reference as it'll never be unlinked. Lose -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/