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-rw-r--r--block/blk-ioprio.c23
1 files changed, 20 insertions, 3 deletions
diff --git a/block/blk-ioprio.c b/block/blk-ioprio.c
index 055529b9b92b..4051fada01f1 100644
--- a/block/blk-ioprio.c
+++ b/block/blk-ioprio.c
@@ -23,25 +23,28 @@
/**
* enum prio_policy - I/O priority class policy.
* @POLICY_NO_CHANGE: (default) do not modify the I/O priority class.
- * @POLICY_NONE_TO_RT: modify IOPRIO_CLASS_NONE into IOPRIO_CLASS_RT.
+ * @POLICY_PROMOTE_TO_RT: modify no-IOPRIO_CLASS_RT to IOPRIO_CLASS_RT.
* @POLICY_RESTRICT_TO_BE: modify IOPRIO_CLASS_NONE and IOPRIO_CLASS_RT into
* IOPRIO_CLASS_BE.
* @POLICY_ALL_TO_IDLE: change the I/O priority class into IOPRIO_CLASS_IDLE.
+ * @POLICY_NONE_TO_RT: an alias for POLICY_PROMOTE_TO_RT.
*
* See also <linux/ioprio.h>.
*/
enum prio_policy {
POLICY_NO_CHANGE = 0,
- POLICY_NONE_TO_RT = 1,
+ POLICY_PROMOTE_TO_RT = 1,
POLICY_RESTRICT_TO_BE = 2,
POLICY_ALL_TO_IDLE = 3,
+ POLICY_NONE_TO_RT = 4,
};
static const char *policy_name[] = {
[POLICY_NO_CHANGE] = "no-change",
- [POLICY_NONE_TO_RT] = "none-to-rt",
+ [POLICY_PROMOTE_TO_RT] = "promote-to-rt",
[POLICY_RESTRICT_TO_BE] = "restrict-to-be",
[POLICY_ALL_TO_IDLE] = "idle",
+ [POLICY_NONE_TO_RT] = "none-to-rt",
};
static struct blkcg_policy ioprio_policy;
@@ -189,6 +192,20 @@ void blkcg_set_ioprio(struct bio *bio)
if (!blkcg || blkcg->prio_policy == POLICY_NO_CHANGE)
return;
+ if (blkcg->prio_policy == POLICY_PROMOTE_TO_RT ||
+ blkcg->prio_policy == POLICY_NONE_TO_RT) {
+ /*
+ * For RT threads, the default priority level is 4 because
+ * task_nice is 0. By promoting non-RT io-priority to RT-class
+ * and default level 4, those requests that are already
+ * RT-class but need a higher io-priority can use ioprio_set()
+ * to achieve this.
+ */
+ if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) != IOPRIO_CLASS_RT)
+ bio->bi_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_RT, 4);
+ return;
+ }
+
/*
* Except for IOPRIO_CLASS_NONE, higher I/O priority numbers
* correspond to a lower priority. Hence, the max_t() below selects