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authorJens Axboe <axboe@kernel.dk>2017-10-25 12:33:42 -0600
committerJens Axboe <axboe@kernel.dk>2017-10-25 12:36:45 -0600
commit2527d99789e248576ac8081530cd4fd88730f8c7 (patch)
treeb3053bb28bcb630c818a7dbe154f2b220a16edd3 /block/elevator.c
parentd5ce4c31d6df518dd8f63bbae20d7423c5018a6c (diff)
downloadlinux-0-day-2527d99789e248576ac8081530cd4fd88730f8c7.tar.gz
elevator: lookup mq vs non-mq elevators
If an IO scheduler is selected via elevator= and it doesn't match the driver in question wrt blk-mq support, then we fail to boot. The elevator= parameter is deprecated and only supported for non-mq devices. Augment the elevator lookup API so that we pass in if we're looking for an mq capable scheduler or not, so that we only ever return a valid type for the queue in question. Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=196695 Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/elevator.c')
-rw-r--r--block/elevator.c44
1 files changed, 21 insertions, 23 deletions
diff --git a/block/elevator.c b/block/elevator.c
index 7ae50eb..77856bf 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -83,12 +83,15 @@ bool elv_bio_merge_ok(struct request *rq, struct bio *bio)
}
EXPORT_SYMBOL(elv_bio_merge_ok);
-static struct elevator_type *elevator_find(const char *name)
+/*
+ * Return scheduler with name 'name' and with matching 'mq capability
+ */
+static struct elevator_type *elevator_find(const char *name, bool mq)
{
struct elevator_type *e;
list_for_each_entry(e, &elv_list, list) {
- if (!strcmp(e->elevator_name, name))
+ if (!strcmp(e->elevator_name, name) && (mq == e->uses_mq))
return e;
}
@@ -100,25 +103,25 @@ static void elevator_put(struct elevator_type *e)
module_put(e->elevator_owner);
}
-static struct elevator_type *elevator_get(const char *name, bool try_loading)
+static struct elevator_type *elevator_get(struct request_queue *q,
+ const char *name, bool try_loading)
{
struct elevator_type *e;
spin_lock(&elv_list_lock);
- e = elevator_find(name);
+ e = elevator_find(name, q->mq_ops != NULL);
if (!e && try_loading) {
spin_unlock(&elv_list_lock);
request_module("%s-iosched", name);
spin_lock(&elv_list_lock);
- e = elevator_find(name);
+ e = elevator_find(name, q->mq_ops != NULL);
}
if (e && !try_module_get(e->elevator_owner))
e = NULL;
spin_unlock(&elv_list_lock);
-
return e;
}
@@ -144,8 +147,12 @@ void __init load_default_elevator_module(void)
if (!chosen_elevator[0])
return;
+ /*
+ * Boot parameter is deprecated, we haven't supported that for MQ.
+ * Only look for non-mq schedulers from here.
+ */
spin_lock(&elv_list_lock);
- e = elevator_find(chosen_elevator);
+ e = elevator_find(chosen_elevator, false);
spin_unlock(&elv_list_lock);
if (!e)
@@ -202,7 +209,7 @@ int elevator_init(struct request_queue *q, char *name)
q->boundary_rq = NULL;
if (name) {
- e = elevator_get(name, true);
+ e = elevator_get(q, name, true);
if (!e)
return -EINVAL;
}
@@ -214,7 +221,7 @@ int elevator_init(struct request_queue *q, char *name)
* allowed from async.
*/
if (!e && !q->mq_ops && *chosen_elevator) {
- e = elevator_get(chosen_elevator, false);
+ e = elevator_get(q, chosen_elevator, false);
if (!e)
printk(KERN_ERR "I/O scheduler %s not found\n",
chosen_elevator);
@@ -229,17 +236,17 @@ int elevator_init(struct request_queue *q, char *name)
*/
if (q->mq_ops) {
if (q->nr_hw_queues == 1)
- e = elevator_get("mq-deadline", false);
+ e = elevator_get(q, "mq-deadline", false);
if (!e)
return 0;
} else
- e = elevator_get(CONFIG_DEFAULT_IOSCHED, false);
+ e = elevator_get(q, CONFIG_DEFAULT_IOSCHED, false);
if (!e) {
printk(KERN_ERR
"Default I/O scheduler not found. " \
"Using noop.\n");
- e = elevator_get("noop", false);
+ e = elevator_get(q, "noop", false);
}
}
@@ -905,7 +912,7 @@ int elv_register(struct elevator_type *e)
/* register, don't allow duplicate names */
spin_lock(&elv_list_lock);
- if (elevator_find(e->elevator_name)) {
+ if (elevator_find(e->elevator_name, e->uses_mq)) {
spin_unlock(&elv_list_lock);
if (e->icq_cache)
kmem_cache_destroy(e->icq_cache);
@@ -1066,7 +1073,7 @@ static int __elevator_change(struct request_queue *q, const char *name)
return elevator_switch(q, NULL);
strlcpy(elevator_name, name, sizeof(elevator_name));
- e = elevator_get(strstrip(elevator_name), true);
+ e = elevator_get(q, strstrip(elevator_name), true);
if (!e)
return -EINVAL;
@@ -1076,15 +1083,6 @@ static int __elevator_change(struct request_queue *q, const char *name)
return 0;
}
- if (!e->uses_mq && q->mq_ops) {
- elevator_put(e);
- return -EINVAL;
- }
- if (e->uses_mq && !q->mq_ops) {
- elevator_put(e);
- return -EINVAL;
- }
-
return elevator_switch(q, e);
}