diff options
| author | Damien Le Moal <damien.lemoal@wdc.com> | 2019-09-05 18:51:31 +0900 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-09-05 19:52:33 -0600 |
| commit | 68c43f133a754c7bf5cb1018bb16dc0821cc43a1 (patch) | |
| tree | 79d8eba4264de5d90e3f8bedd2329e5802c94b6e /include/linux/elevator.h | |
| parent | 954b4a5ce4a806e7c284ce6b2659abdd03d0b6e2 (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 'include/linux/elevator.h')
| -rw-r--r-- | include/linux/elevator.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/elevator.h b/include/linux/elevator.h index 1dd014c9c87b..901bda352dcb 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -76,6 +76,7 @@ struct elevator_type struct elv_fs_entry *elevator_attrs; const char *elevator_name; const char *elevator_alias; + const unsigned int elevator_features; struct module *elevator_owner; #ifdef CONFIG_BLK_DEBUG_FS const struct blk_mq_debugfs_attr *queue_debugfs_attrs; @@ -165,5 +166,12 @@ extern struct request *elv_rb_find(struct rb_root *, sector_t); #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist) #define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist) +/* + * Elevator features. + */ + +/* Supports zoned block devices sequential write constraint */ +#define ELEVATOR_F_ZBD_SEQ_WRITE (1U << 0) + #endif /* CONFIG_BLOCK */ #endif |