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    Subject[PATCH][cfq-cgroups][05/12] Introduce cgroups structure with ioprio entry.
    Date
    From 471798eeeea0d3cdc4c556ec3d663d4a91fd2e05 Mon Sep 17 00:00:00 2001
    From: Satoshi UCHIDA <s-uchida@ap.jp.nec.com>
    Date: Wed, 29 Oct 2008 18:12:51 +0900
    Subject: [PATCH][cfq-cgroups] Introduce cgroups structure with ioprio entry.

    This patch introcude cfq_cgroup structure which is type for
    group control within expanded CFQ scheduler.
    In addition, the cfq_cgroup structure has "ioprio" entry which
    is preference of group for I/O.


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

    ---
    block/cfq-cgroup.c | 148 +++++++++++++++++++++++++++++++++++++++++
    include/linux/cgroup_subsys.h | 6 ++
    2 files changed, 154 insertions(+), 0 deletions(-)

    diff --git a/block/cfq-cgroup.c b/block/cfq-cgroup.c
    index aaa00ef..733980d 100644
    --- a/block/cfq-cgroup.c
    +++ b/block/cfq-cgroup.c
    @@ -15,6 +15,154 @@
    #include <linux/cgroup.h>
    #include <linux/cfq-iosched.h>

    +#define CFQ_CGROUP_MAX_IOPRIO (7)
    +
    +
    +struct cfq_cgroup {
    + struct cgroup_subsys_state css;
    + unsigned int ioprio;
    +};
    +
    +static inline struct cfq_cgroup *cgroup_to_cfq_cgroup(struct cgroup *cont)
    +{
    + return container_of(cgroup_subsys_state(cont, cfq_subsys_id),
    + struct cfq_cgroup, css);
    +}
    +
    +static inline struct cfq_cgroup *task_to_cfq_cgroup(struct task_struct *tsk)
    +{
    + return container_of(task_subsys_state(tsk, cfq_subsys_id),
    + struct cfq_cgroup, css);
    +}
    +
    +
    +static struct cgroup_subsys_state *
    +cfq_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
    +{
    + struct cfq_cgroup *cfqc;
    +
    + if (!capable(CAP_SYS_ADMIN))
    + return ERR_PTR(-EPERM);
    +
    + if (!cgroup_is_descendant(cont))
    + return ERR_PTR(-EPERM);
    +
    + cfqc = kzalloc(sizeof(struct cfq_cgroup), GFP_KERNEL);
    + if (unlikely(!cfqc))
    + return ERR_PTR(-ENOMEM);
    +
    + cfqc->ioprio = 3;
    +
    + return &cfqc->css;
    +}
    +
    +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 = snprintf(page, PAGE_SIZE, "%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;
    + long new_prio;
    + int err;
    + 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 */
    + buffer = kmalloc(nbytes + 1, GFP_KERNEL);
    + if (buffer == NULL)
    + return -ENOMEM;
    +
    + if (copy_from_user(buffer, userbuf, nbytes)) {
    + ret = -EFAULT;
    + goto out;
    + }
    + buffer[nbytes] = 0;
    +
    + err = strict_strtoul(buffer, 10, &new_prio);
    + if ((err) || ((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,
    + .populate = cfq_cgroup_populate,
    + .subsys_id = cfq_subsys_id,
    +};
    +
    +
    /*
    * sysfs parts below -->
    */
    diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
    index 9c22396..a9482aa 100644
    --- a/include/linux/cgroup_subsys.h
    +++ b/include/linux/cgroup_subsys.h
    @@ -54,3 +54,9 @@ SUBSYS(freezer)
    #endif

    /* */
    +
    +#ifdef CONFIG_IOSCHED_CFQ_CGROUP
    +SUBSYS(cfq)
    +#endif
    +
    +/* */
    --
    1.5.6.5



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