common: add discard threads option, descriptions and flags

Signed-off-by: Matt Vandermeulen <[email protected]>

Author: Matt1360

src/common/options/global.yaml.in

@@ -4000,15 +4000,39 @@ options:
   default: false
   with_legacy: true
 - name: bdev_enable_discard
+  desc: send discards to the block device
   type: bool
   level: advanced
   default: false
   with_legacy: true
+  flags:
+  - runtime
+  see_also:
+  - bdev_async_discard
+  - bdev_async_discard_threads
 - name: bdev_async_discard
-  type: bool
+  desc: send discards to the block device in one or more threads
+  type: uint
   level: advanced
   default: false
-  with_legacy: true
+  with_legacy: false
+  flags:
+  - runtime
+  see_also:
+  - bdev_enable_discard
+  - bdev_async_discard_threads
+- name: bdev_async_discard_threads
+  desc: number of discard threads used to issue discards to the device
+  type: uint
+  level: advanced
+  default: 1
+  min: 1
+  with_legacy: false
+  flags:
+  - runtime
+  see_also:
+  - bdev_enable_discard
+  - bdev_async_discard
 - name: bdev_flock_retry_interval
   type: float
   level: advanced