cgroup: add cgroup_v1v2_get_from_[fd/file]()

Add cgroup_v1v2_get_from_fd() and cgroup_v1v2_get_from_file() that
support both cgroup1 and cgroup2.

Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 398f0bce7c21446a294bd123ff444acca0aabac2..a88de5bdeaa9f797302216584ca96dc9fcc2d94f 100644 (file)
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -106,6 +106,7 @@ struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
 
 struct cgroup *cgroup_get_from_path(const char *path);
 struct cgroup *cgroup_get_from_fd(int fd);
+struct cgroup *cgroup_v1v2_get_from_fd(int fd);
 
 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 6d8a5a40c24d875492321b4c47e24105db8d7e04..6349a9fe9ec15c833cefb0f2c20b871e2257b9bf 100644 (file)
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6224,16 +6224,36 @@ void cgroup_fork(struct task_struct *child)
        INIT_LIST_HEAD(&child->cg_list);
 }
 
-static struct cgroup *cgroup_get_from_file(struct file *f)
+/**
+ * cgroup_v1v2_get_from_file - get a cgroup pointer from a file pointer
+ * @f: file corresponding to cgroup_dir
+ *
+ * Find the cgroup from a file pointer associated with a cgroup directory.
+ * Returns a pointer to the cgroup on success. ERR_PTR is returned if the
+ * cgroup cannot be found.
+ */
+static struct cgroup *cgroup_v1v2_get_from_file(struct file *f)
 {
        struct cgroup_subsys_state *css;
-       struct cgroup *cgrp;
 
        css = css_tryget_online_from_dir(f->f_path.dentry, NULL);
        if (IS_ERR(css))
                return ERR_CAST(css);
 
-       cgrp = css->cgroup;
+       return css->cgroup;
+}
+
+/**
+ * cgroup_get_from_file - same as cgroup_v1v2_get_from_file, but only supports
+ * cgroup2.
+ */
+static struct cgroup *cgroup_get_from_file(struct file *f)
+{
+       struct cgroup *cgrp = cgroup_v1v2_get_from_file(f);
+
+       if (IS_ERR(cgrp))
+               return ERR_CAST(cgrp);
+
        if (!cgroup_on_dfl(cgrp)) {
                cgroup_put(cgrp);
                return ERR_PTR(-EBADF);
@@ -6734,14 +6754,14 @@ EXPORT_SYMBOL_GPL(cgroup_get_from_path);
 
 /**
  * cgroup_get_from_fd - get a cgroup pointer from a fd
- * @fd: fd obtained by open(cgroup2_dir)
+ * @fd: fd obtained by open(cgroup_dir)
  *
  * Find the cgroup from a fd which should be obtained
  * by opening a cgroup directory.  Returns a pointer to the
  * cgroup on success. ERR_PTR is returned if the cgroup
  * cannot be found.
  */
-struct cgroup *cgroup_get_from_fd(int fd)
+struct cgroup *cgroup_v1v2_get_from_fd(int fd)
 {
        struct cgroup *cgrp;
        struct file *f;
@@ -6750,10 +6770,28 @@ struct cgroup *cgroup_get_from_fd(int fd)
        if (!f)
                return ERR_PTR(-EBADF);
 
-       cgrp = cgroup_get_from_file(f);
+       cgrp = cgroup_v1v2_get_from_file(f);
        fput(f);
        return cgrp;
 }
+
+/**
+ * cgroup_get_from_fd - same as cgroup_v1v2_get_from_fd, but only supports
+ * cgroup2.
+ */
+struct cgroup *cgroup_get_from_fd(int fd)
+{
+       struct cgroup *cgrp = cgroup_v1v2_get_from_fd(fd);
+
+       if (IS_ERR(cgrp))
+               return ERR_CAST(cgrp);
+
+       if (!cgroup_on_dfl(cgrp)) {
+               cgroup_put(cgrp);
+               return ERR_PTR(-EBADF);
+       }
+       return cgrp;
+}
 EXPORT_SYMBOL_GPL(cgroup_get_from_fd);
 
 static u64 power_of_ten(int power)