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author | Damien Le Moal <damien.lemoal@wdc.com> | 2019-09-05 18:51:31 +0900 |
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committer | Jens Axboe <axboe@kernel.dk> | 2019-09-05 19:52:33 -0600 |
commit | 68c43f133a754c7bf5cb1018bb16dc0821cc43a1 (patch) | |
tree | 79d8eba4264de5d90e3f8bedd2329e5802c94b6e /block | |
parent | 954b4a5ce4a806e7c284ce6b2659abdd03d0b6e2 (diff) | |
download | linux-68c43f133a754c7bf5cb1018bb16dc0821cc43a1.tar.gz linux-68c43f133a754c7bf5cb1018bb16dc0821cc43a1.tar.bz2 linux-68c43f133a754c7bf5cb1018bb16dc0821cc43a1.zip |
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.c | 16 | ||||
-rw-r--r-- | block/elevator.c | 49 | ||||
-rw-r--r-- | block/mq-deadline.c | 1 |
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"); |