[PATCH RFC -next 4/7] blk-iocost: factor out helpers to handle params from ioc_qos_write()

From: Yu Kuai
Date: Wed Jun 12 2024 - 21:51:37 EST

From: Yu Kuai <yukuai3@xxxxxxxxxx>

Currently the procedures are:

1) parse input disk and open the disk;
2) get ioc, if this is the first writer, init iocost;
3) init qos params, by copying from ioc;
4) parse input qos params;
5) update qos params to ioc;

This patch just factor out step 3-5 into separate helpers, there are no
functional changes, and prepare for fulture optimizations:

- move step 3-4 before setp 2, and don't init iocost for invalid input
qos params;
- add a new input, and support to free iocost after step 4;
- support to build iocost as kernel module;

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
block/blk-iocost.c | 155 ++++++++++++++++++++++++++-------------------
1 file changed, 91 insertions(+), 64 deletions(-)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 690ca99dfaca..253143005086 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3206,45 +3206,24 @@ static const match_table_t qos_tokens = {
{ NR_QOS_PARAMS, NULL },
};

-static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
- size_t nbytes, loff_t off)
-{
- struct blkg_conf_ctx ctx;
- struct gendisk *disk;
- struct ioc *ioc;
+struct ioc_qos_params {
u32 qos[NR_QOS_PARAMS];
- bool enable, user;
- char *body, *p;
- int ret;
-
- blkg_conf_init(&ctx, input);
-
- ret = blkg_conf_open_bdev(&ctx);
- if (ret)
- goto err;
-
- body = ctx.body;
- disk = ctx.bdev->bd_disk;
- if (!queue_is_mq(disk->queue)) {
- ret = -EOPNOTSUPP;
- goto err;
- }
-
- ioc = q_to_ioc(disk->queue);
- if (!ioc) {
- ret = blk_iocost_init(disk);
- if (ret)
- goto err;
- ioc = q_to_ioc(disk->queue);
- }
+ bool enable;
+ bool user;
+};

- blk_mq_freeze_queue(disk->queue);
- blk_mq_quiesce_queue(disk->queue);
+static void ioc_qos_params_init(struct ioc *ioc, struct ioc_qos_params *params)
+{
+ memcpy(params->qos, ioc->params.qos, sizeof(params->qos));
+ params->enable = ioc->enabled;
+ params->user = ioc->user_qos_params;
+}

- spin_lock_irq(&ioc->lock);
- memcpy(qos, ioc->params.qos, sizeof(qos));
- enable = ioc->enabled;
- user = ioc->user_qos_params;
+static int ioc_qos_params_parse(struct blkg_conf_ctx *ctx,
+ struct ioc_qos_params *params)
+{
+ char *body = ctx->body;
+ char *p;

while ((p = strsep(&body, " \t\n"))) {
substring_t args[MAX_OPT_ARGS];
@@ -3258,17 +3237,17 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
switch (match_token(p, qos_ctrl_tokens, args)) {
case QOS_ENABLE:
if (match_u64(&args[0], &v))
- goto einval;
- enable = v;
+ return -EINVAL;
+ params->enable = v;
continue;
case QOS_CTRL:
match_strlcpy(buf, &args[0], sizeof(buf));
if (!strcmp(buf, "auto"))
- user = false;
+ params->user = false;
else if (!strcmp(buf, "user"))
- user = true;
+ params->user = true;
else
- goto einval;
+ return -EINVAL;
continue;
}

@@ -3278,61 +3257,110 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
case QOS_WPPM:
if (match_strlcpy(buf, &args[0], sizeof(buf)) >=
sizeof(buf))
- goto einval;
+ return -EINVAL;
if (cgroup_parse_float(buf, 2, &v))
- goto einval;
+ return -EINVAL;
if (v < 0 || v > 10000)
- goto einval;
- qos[tok] = v * 100;
+ return -EINVAL;
+ params->qos[tok] = v * 100;
break;
case QOS_RLAT:
case QOS_WLAT:
if (match_u64(&args[0], &v))
- goto einval;
- qos[tok] = v;
+ return -EINVAL;
+ params->qos[tok] = v;
break;
case QOS_MIN:
case QOS_MAX:
if (match_strlcpy(buf, &args[0], sizeof(buf)) >=
sizeof(buf))
- goto einval;
+ return -EINVAL;
if (cgroup_parse_float(buf, 2, &v))
- goto einval;
+ return -EINVAL;
if (v < 0)
- goto einval;
- qos[tok] = clamp_t(s64, v * 100,
- VRATE_MIN_PPM, VRATE_MAX_PPM);
+ return -EINVAL;
+ params->qos[tok] = clamp_t(s64, v * 100,
+ VRATE_MIN_PPM,
+ VRATE_MAX_PPM);
break;
default:
- goto einval;
+ return -EINVAL;
}
- user = true;
+ params->user = true;
}

- if (qos[QOS_MIN] > qos[QOS_MAX])
- goto einval;
+ if (params->qos[QOS_MIN] > params->qos[QOS_MAX])
+ return -EINVAL;
+
+ return 0;
+}

- if (enable && !ioc->enabled) {
+static void ioc_qos_params_update(struct gendisk *disk, struct ioc *ioc,
+ struct ioc_qos_params *params)
+{
+ if (params->enable && !ioc->enabled) {
blk_stat_enable_accounting(disk->queue);
blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue);
ioc->enabled = true;
- } else if (!enable && ioc->enabled) {
+ } else if (!params->enable && ioc->enabled) {
blk_stat_disable_accounting(disk->queue);
blk_queue_flag_clear(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue);
ioc->enabled = false;
}

- if (user) {
- memcpy(ioc->params.qos, qos, sizeof(qos));
+ if (params->user) {
+ memcpy(ioc->params.qos, params->qos, sizeof(params->qos));
ioc->user_qos_params = true;
} else {
ioc->user_qos_params = false;
}

ioc_refresh_params(ioc, true);
+}
+
+static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
+ size_t nbytes, loff_t off)
+{
+ struct ioc_qos_params params;
+ struct blkg_conf_ctx ctx;
+ struct gendisk *disk;
+ struct ioc *ioc;
+ int ret;
+
+ blkg_conf_init(&ctx, input);
+
+ ret = blkg_conf_open_bdev(&ctx);
+ if (ret)
+ goto err;
+
+ disk = ctx.bdev->bd_disk;
+ if (!queue_is_mq(disk->queue)) {
+ ret = -EOPNOTSUPP;
+ goto err;
+ }
+
+ ioc = q_to_ioc(disk->queue);
+ if (!ioc) {
+ ret = blk_iocost_init(disk);
+ if (ret)
+ goto err;
+ ioc = q_to_ioc(disk->queue);
+ }
+
+ blk_mq_freeze_queue(disk->queue);
+ blk_mq_quiesce_queue(disk->queue);
+
+ spin_lock_irq(&ioc->lock);
+ ioc_qos_params_init(ioc, &params);
+
+ ret = ioc_qos_params_parse(&ctx, &params);
+ if (ret)
+ goto err_parse;
+
+ ioc_qos_params_update(disk, ioc, &params);
spin_unlock_irq(&ioc->lock);

- if (enable)
+ if (params.enable)
wbt_disable_default(disk);
else
wbt_enable_default(disk);
@@ -3342,13 +3370,12 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,

blkg_conf_exit(&ctx);
return nbytes;
-einval:
+
+err_parse:
spin_unlock_irq(&ioc->lock);

blk_mq_unquiesce_queue(disk->queue);
blk_mq_unfreeze_queue(disk->queue);
-
- ret = -EINVAL;
err:
blkg_conf_exit(&ctx);
return ret;
--
2.39.2