cgroup: export fhandle info for a cgroup (121508df) · Commits · e / devices / android_kernel_fairphone_FP4

Add an API to export cgroup fhandle info. We don't export a full 'struct file_handle', there are unrequired info. Sepcifically, cgroup is always a directory, so we don't need a 'FILEID_INO32_GEN_PARENT' type fhandle, we only need export the inode number and generation number just like what generic_fh_to_dentry does. And we can avoid the overhead of getting an inode too, since kernfs_node_id (ino and generation) has all the info required. Acked-by:

Tejun Heo <tj@kernel.org> Signed-off-by:

Shaohua Li <shli@fb.com> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

include/linux/cgroup.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -609,6 +609,10 @@ static inline void cgroup_kthread_ready(void)
		current->no_cgroup_migration = 0;
		}

		static inline union kernfs_node_id cgroup_get_kernfs_id(struct cgroup cgrp)
		{
		return &cgrp->kn->id;
		}
		#else /* !CONFIG_CGROUPS */

		struct cgroup_subsys_state;
		@@ -631,6 +635,10 @@ static inline int cgroup_init_early(void) { return 0; }
		static inline int cgroup_init(void) { return 0; }
		static inline void cgroup_init_kthreadd(void) {}
		static inline void cgroup_kthread_ready(void) {}
		static inline union kernfs_node_id cgroup_get_kernfs_id(struct cgroup cgrp)
		{
		return NULL;
		}

		static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
		struct cgroup *ancestor)