aboutsummaryrefslogtreecommitdiffstats
path: root/block
diff options
context:
space:
mode:
authorDamien Le Moal <damien.lemoal@wdc.com>2019-09-05 18:51:31 +0900
committerJens Axboe <axboe@kernel.dk>2019-09-05 19:52:33 -0600
commit68c43f133a754c7bf5cb1018bb16dc0821cc43a1 (patch)
tree79d8eba4264de5d90e3f8bedd2329e5802c94b6e /block
parent954b4a5ce4a806e7c284ce6b2659abdd03d0b6e2 (diff)
block: Introduce elevator features
Introduce the definition of elevator features through the elevator_features flags in the elevator_type structure. Each flag can represent a feature supported by an elevator. The first feature defined by this patch is support for zoned block device sequential write constraint with the flag ELEVATOR_F_ZBD_SEQ_WRITE, which is implemented by the mq-deadline elevator using zone write locking. Other possible features are IO priorities, write hints, latency targets or single-LUN dual-actuator disks (for which the elevator could maintain one LBA ordered list per actuator). The required_elevator_features field is also added to the request_queue structure to allow a device driver to specify elevator feature flags that an elevator must support for the correct operation of the device (e.g. device drivers for zoned block devices can have the ELEVATOR_F_ZBD_SEQ_WRITE flag as a required feature). The helper function blk_queue_required_elevator_features() is defined for setting this new field. With these two new fields in place, the elevator functions elevator_match() and elevator_find() are modified to allow a user to set only an elevator with a set of features that satisfies the device required features. Elevators not matching the device requirements are not shown in the device sysfs queue/scheduler file to prevent their use. The "none" elevator can always be selected as before. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-settings.c16
-rw-r--r--block/elevator.c49
-rw-r--r--block/mq-deadline.c1
3 files changed, 55 insertions, 11 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
index a058997b9cce..6bd1e3b082d8 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -832,6 +832,22 @@ void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
}
EXPORT_SYMBOL_GPL(blk_queue_write_cache);
+/**
+ * blk_queue_required_elevator_features - Set a queue required elevator features
+ * @q: the request queue for the target device
+ * @features: Required elevator features OR'ed together
+ *
+ * Tell the block layer that for the device controlled through @q, only the
+ * only elevators that can be used are those that implement at least the set of
+ * features specified by @features.
+ */
+void blk_queue_required_elevator_features(struct request_queue *q,
+ unsigned int features)
+{
+ q->required_elevator_features = features;
+}
+EXPORT_SYMBOL_GPL(blk_queue_required_elevator_features);
+
static int __init blk_settings_init(void)
{
blk_max_low_pfn = max_low_pfn - 1;
diff --git a/block/elevator.c b/block/elevator.c
index 2944c129760c..ac7c8ad580ba 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -83,8 +83,26 @@ bool elv_bio_merge_ok(struct request *rq, struct bio *bio)
}
EXPORT_SYMBOL(elv_bio_merge_ok);
-static bool elevator_match(const struct elevator_type *e, const char *name)
+static inline bool elv_support_features(unsigned int elv_features,
+ unsigned int required_features)
{
+ return (required_features & elv_features) == required_features;
+}
+
+/**
+ * elevator_match - Test an elevator name and features
+ * @e: Scheduler to test
+ * @name: Elevator name to test
+ * @required_features: Features that the elevator must provide
+ *
+ * Return true is the elevator @e name matches @name and if @e provides all the
+ * the feratures spcified by @required_features.
+ */
+static bool elevator_match(const struct elevator_type *e, const char *name,
+ unsigned int required_features)
+{
+ if (!elv_support_features(e->elevator_features, required_features))
+ return false;
if (!strcmp(e->elevator_name, name))
return true;
if (e->elevator_alias && !strcmp(e->elevator_alias, name))
@@ -93,15 +111,21 @@ static bool elevator_match(const struct elevator_type *e, const char *name)
return false;
}
-/*
- * Return scheduler with name 'name'
+/**
+ * elevator_find - Find an elevator
+ * @name: Name of the elevator to find
+ * @required_features: Features that the elevator must provide
+ *
+ * Return the first registered scheduler with name @name and supporting the
+ * features @required_features and NULL otherwise.
*/
-static struct elevator_type *elevator_find(const char *name)
+static struct elevator_type *elevator_find(const char *name,
+ unsigned int required_features)
{
struct elevator_type *e;
list_for_each_entry(e, &elv_list, list) {
- if (elevator_match(e, name))
+ if (elevator_match(e, name, required_features))
return e;
}
@@ -120,12 +144,12 @@ static struct elevator_type *elevator_get(struct request_queue *q,
spin_lock(&elv_list_lock);
- e = elevator_find(name);
+ e = elevator_find(name, q->required_elevator_features);
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->required_elevator_features);
}
if (e && !try_module_get(e->elevator_owner))
@@ -525,7 +549,7 @@ 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, 0)) {
spin_unlock(&elv_list_lock);
kmem_cache_destroy(e->icq_cache);
return -EBUSY;
@@ -709,7 +733,8 @@ static int __elevator_change(struct request_queue *q, const char *name)
if (!e)
return -EINVAL;
- if (q->elevator && elevator_match(q->elevator->type, elevator_name)) {
+ if (q->elevator &&
+ elevator_match(q->elevator->type, elevator_name, 0)) {
elevator_put(e);
return 0;
}
@@ -749,11 +774,13 @@ ssize_t elv_iosched_show(struct request_queue *q, char *name)
spin_lock(&elv_list_lock);
list_for_each_entry(__e, &elv_list, list) {
- if (elv && elevator_match(elv, __e->elevator_name)) {
+ if (elv && elevator_match(elv, __e->elevator_name, 0)) {
len += sprintf(name+len, "[%s] ", elv->elevator_name);
continue;
}
- if (elv_support_iosched(q))
+ if (elv_support_iosched(q) &&
+ elevator_match(__e, __e->elevator_name,
+ q->required_elevator_features))
len += sprintf(name+len, "%s ", __e->elevator_name);
}
spin_unlock(&elv_list_lock);
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 35e84bc0ec8c..b490f47fd553 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -794,6 +794,7 @@ static struct elevator_type mq_deadline = {
.elevator_attrs = deadline_attrs,
.elevator_name = "mq-deadline",
.elevator_alias = "deadline",
+ .elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE,
.elevator_owner = THIS_MODULE,
};
MODULE_ALIAS("mq-deadline-iosched");

Privacy Policy