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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/blk-settings.c | |
parent | 954b4a5ce4a806e7c284ce6b2659abdd03d0b6e2 (diff) | |
download | linux-stable-68c43f133a754c7bf5cb1018bb16dc0821cc43a1.tar.gz linux-stable-68c43f133a754c7bf5cb1018bb16dc0821cc43a1.tar.bz2 linux-stable-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/blk-settings.c')
-rw-r--r-- | block/blk-settings.c | 16 |
1 files changed, 16 insertions, 0 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; |