[PATCH] [RFC][patch 4/12][CFQ-cgroup] Add ioprio entry

["Satoshi UCHIDA" <s-uchida@ap.jp.nec.com>]

This patch add "ioprio" entry in cfq_cgroup.
The "ioprio" entry shows I/O priority of group.
When you would change priority, write this entry.

      Signed-off-by: Satoshi UCHIDA <uchida@ap.jp.nec.com>

---
 block/cfq-cgroup.c |   96 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 96 insertions(+), 0 deletions(-)

diff --git a/block/cfq-cgroup.c b/block/cfq-cgroup.c
index de00a0d..378a23d 100644
--- a/block/cfq-cgroup.c
+++ b/block/cfq-cgroup.c
@@ -15,8 +15,12 @@
 #include <linux/cgroup.h>
 #include <linux/cfq-iosched.h>
 
+#define CFQ_CGROUP_SLICE_SCALE		(5)
+#define CFQ_CGROUP_MAX_IOPRIO		(8)
+
 struct cfq_cgroup {
 	struct cgroup_subsys_state css;
+	unsigned int ioprio;
 };
 
 
@@ -41,6 +45,8 @@ cfq_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 	if (unlikely(!cfqc))
 		return ERR_PTR(-ENOMEM);
 
+	cfqc->ioprio = 3;
+
 	return &cfqc->css;	
 }
 
@@ -49,9 +55,99 @@ static void cfq_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
 	kfree(cgroup_to_cfq_cgroup(cont));
 }
 
+static ssize_t cfq_cgroup_read(struct cgroup *cont, struct cftype *cft,
+			       struct file *file, char __user *userbuf,
+			       size_t nbytes, loff_t *ppos)
+{
+	struct cfq_cgroup *cfqc;
+	char *page;
+	ssize_t ret;
+
+	page = (char *)__get_free_page(GFP_TEMPORARY);
+	if (!page)
+		return -ENOMEM;
+
+	cgroup_lock();
+	if (cgroup_is_removed(cont)) {
+		cgroup_unlock();
+		ret = -ENODEV;
+		goto out;
+	}
+
+	cfqc = cgroup_to_cfq_cgroup(cont);
+
+	cgroup_unlock();
+
+	/* print priority */
+	ret = sprintf(page, " priority: %d \n", cfqc->ioprio);
+
+	ret = simple_read_from_buffer(userbuf, nbytes, ppos, page, ret);
+
+out:
+	free_page((unsigned long)page);
+	return ret;
+}
+
+static ssize_t cfq_cgroup_write(struct cgroup *cont, struct cftype *cft,
+				struct file *file, const char __user *userbuf,
+				size_t nbytes, loff_t *ppos)
+{
+	struct cfq_cgroup *cfqc;
+	ssize_t ret;
+	int new_prio;
+	char *buffer = NULL;
+
+	cgroup_lock();
+	if (cgroup_is_removed(cont)) {
+		cgroup_unlock();
+		ret = -ENODEV;
+		goto out;
+	}
+
+	cfqc = cgroup_to_cfq_cgroup(cont);
+	cgroup_unlock();
+
+	/* set priority */
+	if ((buffer = kmalloc(nbytes + 1, GFP_KERNEL)) == 0)
+		return -ENOMEM;
+	
+	if (copy_from_user(buffer, userbuf, nbytes)) {
+		ret = -EFAULT;
+		goto out;
+	}
+	buffer[nbytes]=0;
+
+	new_prio = simple_strtoul(buffer, NULL, 10);
+	if ((new_prio < 0) || (new_prio > CFQ_CGROUP_MAX_IOPRIO)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	cfqc->ioprio = new_prio;
+	ret = nbytes;
+	
+out:
+	kfree(buffer);
+	return ret;
+}
+
+static struct cftype files[] = {
+	{
+		.name = "ioprio",
+		.read = cfq_cgroup_read,
+		.write = cfq_cgroup_write,
+	},
+};
+
+static int cfq_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+	return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
+}
+
 struct cgroup_subsys cfq_subsys = {
 	.name = "cfq",
 	.create = cfq_cgroup_create,
 	.destroy = cfq_cgroup_destroy,
 	.subsys_id = cfq_subsys_id,
+	.populate = cfq_cgroup_populate,
 };
-- 
1.5.4.1