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authorTejun Heo <tj@kernel.org>2015-08-18 14:55:04 -0700
committerJens Axboe <axboe@fb.com>2015-08-18 15:49:16 -0700
commitd4aad7ff04dfd00f2a69356a48054d6be84dda31 (patch)
treed1e9b3a0300ff41f977ae790b6d91fb557ac5093 /block
parent322731ed0dd2d8a7f11307e0444257f48580a0de (diff)
downloadlinux-d4aad7ff04dfd00f2a69356a48054d6be84dda31.tar.bz2
cfq-iosched: fold cfq_find_alloc_queue() into cfq_get_queue()
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 <tj@kernel.org> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c49
1 files changed, 15 insertions, 34 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index f3ea8a198def..fa2a2f7dbecd 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