Add the per-directory "tasks" file for cgroupfs mounts; this allows the user to determine which tasks are members of a cgroup by reading a cgroup's "tasks", and to move a task into a cgroup by writing its pid to its "tasks". Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1556 lines
38 KiB
C
1556 lines
38 KiB
C
/*
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* kernel/cgroup.c
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*
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* Generic process-grouping system.
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*
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* Based originally on the cpuset system, extracted by Paul Menage
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* Copyright (C) 2006 Google, Inc
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*
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* Copyright notices from the original cpuset code:
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* --------------------------------------------------
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* Copyright (C) 2003 BULL SA.
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* Copyright (C) 2004-2006 Silicon Graphics, Inc.
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*
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* Portions derived from Patrick Mochel's sysfs code.
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* sysfs is Copyright (c) 2001-3 Patrick Mochel
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*
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* 2003-10-10 Written by Simon Derr.
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* 2003-10-22 Updates by Stephen Hemminger.
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* 2004 May-July Rework by Paul Jackson.
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* ---------------------------------------------------
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of the Linux
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* distribution for more details.
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*/
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#include <linux/cgroup.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include <linux/mount.h>
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#include <linux/pagemap.h>
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#include <linux/rcupdate.h>
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#include <linux/sched.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include <linux/magic.h>
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#include <linux/spinlock.h>
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#include <linux/string.h>
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#include <linux/sort.h>
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#include <asm/atomic.h>
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/* Generate an array of cgroup subsystem pointers */
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#define SUBSYS(_x) &_x ## _subsys,
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static struct cgroup_subsys *subsys[] = {
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#include <linux/cgroup_subsys.h>
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};
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/*
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* A cgroupfs_root represents the root of a cgroup hierarchy,
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* and may be associated with a superblock to form an active
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* hierarchy
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*/
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struct cgroupfs_root {
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struct super_block *sb;
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/*
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* The bitmask of subsystems intended to be attached to this
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* hierarchy
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*/
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unsigned long subsys_bits;
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/* The bitmask of subsystems currently attached to this hierarchy */
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unsigned long actual_subsys_bits;
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/* A list running through the attached subsystems */
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struct list_head subsys_list;
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/* The root cgroup for this hierarchy */
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struct cgroup top_cgroup;
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/* Tracks how many cgroups are currently defined in hierarchy.*/
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int number_of_cgroups;
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/* A list running through the mounted hierarchies */
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struct list_head root_list;
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/* Hierarchy-specific flags */
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unsigned long flags;
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};
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/*
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* The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
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* subsystems that are otherwise unattached - it never has more than a
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* single cgroup, and all tasks are part of that cgroup.
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*/
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static struct cgroupfs_root rootnode;
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/* The list of hierarchy roots */
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static LIST_HEAD(roots);
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/* dummytop is a shorthand for the dummy hierarchy's top cgroup */
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#define dummytop (&rootnode.top_cgroup)
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/* This flag indicates whether tasks in the fork and exit paths should
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* take callback_mutex and check for fork/exit handlers to call. This
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* avoids us having to do extra work in the fork/exit path if none of the
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* subsystems need to be called.
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*/
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static int need_forkexit_callback;
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/* bits in struct cgroup flags field */
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enum {
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CONT_REMOVED,
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};
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/* convenient tests for these bits */
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inline int cgroup_is_removed(const struct cgroup *cont)
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{
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return test_bit(CONT_REMOVED, &cont->flags);
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}
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/* bits in struct cgroupfs_root flags field */
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enum {
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ROOT_NOPREFIX, /* mounted subsystems have no named prefix */
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};
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/*
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* for_each_subsys() allows you to iterate on each subsystem attached to
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* an active hierarchy
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*/
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#define for_each_subsys(_root, _ss) \
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list_for_each_entry(_ss, &_root->subsys_list, sibling)
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/* for_each_root() allows you to iterate across the active hierarchies */
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#define for_each_root(_root) \
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list_for_each_entry(_root, &roots, root_list)
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/*
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* There is one global cgroup mutex. We also require taking
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* task_lock() when dereferencing a task's cgroup subsys pointers.
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* See "The task_lock() exception", at the end of this comment.
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*
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* A task must hold cgroup_mutex to modify cgroups.
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*
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* Any task can increment and decrement the count field without lock.
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* So in general, code holding cgroup_mutex can't rely on the count
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* field not changing. However, if the count goes to zero, then only
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* attach_task() can increment it again. Because a count of zero
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* means that no tasks are currently attached, therefore there is no
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* way a task attached to that cgroup can fork (the other way to
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* increment the count). So code holding cgroup_mutex can safely
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* assume that if the count is zero, it will stay zero. Similarly, if
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* a task holds cgroup_mutex on a cgroup with zero count, it
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* knows that the cgroup won't be removed, as cgroup_rmdir()
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* needs that mutex.
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*
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* The cgroup_common_file_write handler for operations that modify
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* the cgroup hierarchy holds cgroup_mutex across the entire operation,
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* single threading all such cgroup modifications across the system.
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*
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* The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
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* (usually) take cgroup_mutex. These are the two most performance
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* critical pieces of code here. The exception occurs on cgroup_exit(),
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* when a task in a notify_on_release cgroup exits. Then cgroup_mutex
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* is taken, and if the cgroup count is zero, a usermode call made
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* to /sbin/cgroup_release_agent with the name of the cgroup (path
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* relative to the root of cgroup file system) as the argument.
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*
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* A cgroup can only be deleted if both its 'count' of using tasks
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* is zero, and its list of 'children' cgroups is empty. Since all
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* tasks in the system use _some_ cgroup, and since there is always at
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* least one task in the system (init, pid == 1), therefore, top_cgroup
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* always has either children cgroups and/or using tasks. So we don't
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* need a special hack to ensure that top_cgroup cannot be deleted.
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*
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* The task_lock() exception
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*
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* The need for this exception arises from the action of
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* attach_task(), which overwrites one tasks cgroup pointer with
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* another. It does so using cgroup_mutexe, however there are
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* several performance critical places that need to reference
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* task->cgroup without the expense of grabbing a system global
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* mutex. Therefore except as noted below, when dereferencing or, as
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* in attach_task(), modifying a task'ss cgroup pointer we use
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* task_lock(), which acts on a spinlock (task->alloc_lock) already in
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* the task_struct routinely used for such matters.
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*
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* P.S. One more locking exception. RCU is used to guard the
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* update of a tasks cgroup pointer by attach_task()
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*/
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static DEFINE_MUTEX(cgroup_mutex);
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/**
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* cgroup_lock - lock out any changes to cgroup structures
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*
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*/
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void cgroup_lock(void)
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{
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mutex_lock(&cgroup_mutex);
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}
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/**
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* cgroup_unlock - release lock on cgroup changes
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*
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* Undo the lock taken in a previous cgroup_lock() call.
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*/
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void cgroup_unlock(void)
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{
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mutex_unlock(&cgroup_mutex);
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}
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/*
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* A couple of forward declarations required, due to cyclic reference loop:
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* cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
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* cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
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* -> cgroup_mkdir.
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*/
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static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode);
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static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry);
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static int cgroup_populate_dir(struct cgroup *cont);
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static struct inode_operations cgroup_dir_inode_operations;
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static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
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{
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struct inode *inode = new_inode(sb);
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static struct backing_dev_info cgroup_backing_dev_info = {
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.capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
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};
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if (inode) {
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inode->i_mode = mode;
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inode->i_uid = current->fsuid;
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inode->i_gid = current->fsgid;
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inode->i_blocks = 0;
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inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info;
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}
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return inode;
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}
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static void cgroup_diput(struct dentry *dentry, struct inode *inode)
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{
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/* is dentry a directory ? if so, kfree() associated cgroup */
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if (S_ISDIR(inode->i_mode)) {
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struct cgroup *cont = dentry->d_fsdata;
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BUG_ON(!(cgroup_is_removed(cont)));
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kfree(cont);
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}
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iput(inode);
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}
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static void remove_dir(struct dentry *d)
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{
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struct dentry *parent = dget(d->d_parent);
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d_delete(d);
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simple_rmdir(parent->d_inode, d);
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dput(parent);
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}
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static void cgroup_clear_directory(struct dentry *dentry)
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{
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struct list_head *node;
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BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
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spin_lock(&dcache_lock);
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node = dentry->d_subdirs.next;
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while (node != &dentry->d_subdirs) {
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struct dentry *d = list_entry(node, struct dentry, d_u.d_child);
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list_del_init(node);
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if (d->d_inode) {
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/* This should never be called on a cgroup
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* directory with child cgroups */
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BUG_ON(d->d_inode->i_mode & S_IFDIR);
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d = dget_locked(d);
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spin_unlock(&dcache_lock);
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d_delete(d);
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simple_unlink(dentry->d_inode, d);
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dput(d);
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spin_lock(&dcache_lock);
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}
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node = dentry->d_subdirs.next;
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}
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spin_unlock(&dcache_lock);
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}
|
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|
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/*
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* NOTE : the dentry must have been dget()'ed
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*/
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static void cgroup_d_remove_dir(struct dentry *dentry)
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{
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cgroup_clear_directory(dentry);
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spin_lock(&dcache_lock);
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list_del_init(&dentry->d_u.d_child);
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spin_unlock(&dcache_lock);
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remove_dir(dentry);
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}
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|
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static int rebind_subsystems(struct cgroupfs_root *root,
|
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unsigned long final_bits)
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{
|
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unsigned long added_bits, removed_bits;
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struct cgroup *cont = &root->top_cgroup;
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int i;
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|
|
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removed_bits = root->actual_subsys_bits & ~final_bits;
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added_bits = final_bits & ~root->actual_subsys_bits;
|
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/* Check that any added subsystems are currently free */
|
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
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unsigned long long bit = 1ull << i;
|
|
struct cgroup_subsys *ss = subsys[i];
|
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if (!(bit & added_bits))
|
|
continue;
|
|
if (ss->root != &rootnode) {
|
|
/* Subsystem isn't free */
|
|
return -EBUSY;
|
|
}
|
|
}
|
|
|
|
/* Currently we don't handle adding/removing subsystems when
|
|
* any child cgroups exist. This is theoretically supportable
|
|
* but involves complex error handling, so it's being left until
|
|
* later */
|
|
if (!list_empty(&cont->children))
|
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return -EBUSY;
|
|
|
|
/* Process each subsystem */
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
unsigned long bit = 1UL << i;
|
|
if (bit & added_bits) {
|
|
/* We're binding this subsystem to this hierarchy */
|
|
BUG_ON(cont->subsys[i]);
|
|
BUG_ON(!dummytop->subsys[i]);
|
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BUG_ON(dummytop->subsys[i]->cgroup != dummytop);
|
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cont->subsys[i] = dummytop->subsys[i];
|
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cont->subsys[i]->cgroup = cont;
|
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list_add(&ss->sibling, &root->subsys_list);
|
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rcu_assign_pointer(ss->root, root);
|
|
if (ss->bind)
|
|
ss->bind(ss, cont);
|
|
|
|
} else if (bit & removed_bits) {
|
|
/* We're removing this subsystem */
|
|
BUG_ON(cont->subsys[i] != dummytop->subsys[i]);
|
|
BUG_ON(cont->subsys[i]->cgroup != cont);
|
|
if (ss->bind)
|
|
ss->bind(ss, dummytop);
|
|
dummytop->subsys[i]->cgroup = dummytop;
|
|
cont->subsys[i] = NULL;
|
|
rcu_assign_pointer(subsys[i]->root, &rootnode);
|
|
list_del(&ss->sibling);
|
|
} else if (bit & final_bits) {
|
|
/* Subsystem state should already exist */
|
|
BUG_ON(!cont->subsys[i]);
|
|
} else {
|
|
/* Subsystem state shouldn't exist */
|
|
BUG_ON(cont->subsys[i]);
|
|
}
|
|
}
|
|
root->subsys_bits = root->actual_subsys_bits = final_bits;
|
|
synchronize_rcu();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs)
|
|
{
|
|
struct cgroupfs_root *root = vfs->mnt_sb->s_fs_info;
|
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struct cgroup_subsys *ss;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
for_each_subsys(root, ss)
|
|
seq_printf(seq, ",%s", ss->name);
|
|
if (test_bit(ROOT_NOPREFIX, &root->flags))
|
|
seq_puts(seq, ",noprefix");
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
struct cgroup_sb_opts {
|
|
unsigned long subsys_bits;
|
|
unsigned long flags;
|
|
};
|
|
|
|
/* Convert a hierarchy specifier into a bitmask of subsystems and
|
|
* flags. */
|
|
static int parse_cgroupfs_options(char *data,
|
|
struct cgroup_sb_opts *opts)
|
|
{
|
|
char *token, *o = data ?: "all";
|
|
|
|
opts->subsys_bits = 0;
|
|
opts->flags = 0;
|
|
|
|
while ((token = strsep(&o, ",")) != NULL) {
|
|
if (!*token)
|
|
return -EINVAL;
|
|
if (!strcmp(token, "all")) {
|
|
opts->subsys_bits = (1 << CGROUP_SUBSYS_COUNT) - 1;
|
|
} else if (!strcmp(token, "noprefix")) {
|
|
set_bit(ROOT_NOPREFIX, &opts->flags);
|
|
} else {
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
ss = subsys[i];
|
|
if (!strcmp(token, ss->name)) {
|
|
set_bit(i, &opts->subsys_bits);
|
|
break;
|
|
}
|
|
}
|
|
if (i == CGROUP_SUBSYS_COUNT)
|
|
return -ENOENT;
|
|
}
|
|
}
|
|
|
|
/* We can't have an empty hierarchy */
|
|
if (!opts->subsys_bits)
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_remount(struct super_block *sb, int *flags, char *data)
|
|
{
|
|
int ret = 0;
|
|
struct cgroupfs_root *root = sb->s_fs_info;
|
|
struct cgroup *cont = &root->top_cgroup;
|
|
struct cgroup_sb_opts opts;
|
|
|
|
mutex_lock(&cont->dentry->d_inode->i_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* See what subsystems are wanted */
|
|
ret = parse_cgroupfs_options(data, &opts);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
/* Don't allow flags to change at remount */
|
|
if (opts.flags != root->flags) {
|
|
ret = -EINVAL;
|
|
goto out_unlock;
|
|
}
|
|
|
|
ret = rebind_subsystems(root, opts.subsys_bits);
|
|
|
|
/* (re)populate subsystem files */
|
|
if (!ret)
|
|
cgroup_populate_dir(cont);
|
|
|
|
out_unlock:
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cont->dentry->d_inode->i_mutex);
|
|
return ret;
|
|
}
|
|
|
|
static struct super_operations cgroup_ops = {
|
|
.statfs = simple_statfs,
|
|
.drop_inode = generic_delete_inode,
|
|
.show_options = cgroup_show_options,
|
|
.remount_fs = cgroup_remount,
|
|
};
|
|
|
|
static void init_cgroup_root(struct cgroupfs_root *root)
|
|
{
|
|
struct cgroup *cont = &root->top_cgroup;
|
|
INIT_LIST_HEAD(&root->subsys_list);
|
|
INIT_LIST_HEAD(&root->root_list);
|
|
root->number_of_cgroups = 1;
|
|
cont->root = root;
|
|
cont->top_cgroup = cont;
|
|
INIT_LIST_HEAD(&cont->sibling);
|
|
INIT_LIST_HEAD(&cont->children);
|
|
}
|
|
|
|
static int cgroup_test_super(struct super_block *sb, void *data)
|
|
{
|
|
struct cgroupfs_root *new = data;
|
|
struct cgroupfs_root *root = sb->s_fs_info;
|
|
|
|
/* First check subsystems */
|
|
if (new->subsys_bits != root->subsys_bits)
|
|
return 0;
|
|
|
|
/* Next check flags */
|
|
if (new->flags != root->flags)
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int cgroup_set_super(struct super_block *sb, void *data)
|
|
{
|
|
int ret;
|
|
struct cgroupfs_root *root = data;
|
|
|
|
ret = set_anon_super(sb, NULL);
|
|
if (ret)
|
|
return ret;
|
|
|
|
sb->s_fs_info = root;
|
|
root->sb = sb;
|
|
|
|
sb->s_blocksize = PAGE_CACHE_SIZE;
|
|
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
|
|
sb->s_magic = CGROUP_SUPER_MAGIC;
|
|
sb->s_op = &cgroup_ops;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_get_rootdir(struct super_block *sb)
|
|
{
|
|
struct inode *inode =
|
|
cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb);
|
|
struct dentry *dentry;
|
|
|
|
if (!inode)
|
|
return -ENOMEM;
|
|
|
|
inode->i_op = &simple_dir_inode_operations;
|
|
inode->i_fop = &simple_dir_operations;
|
|
inode->i_op = &cgroup_dir_inode_operations;
|
|
/* directories start off with i_nlink == 2 (for "." entry) */
|
|
inc_nlink(inode);
|
|
dentry = d_alloc_root(inode);
|
|
if (!dentry) {
|
|
iput(inode);
|
|
return -ENOMEM;
|
|
}
|
|
sb->s_root = dentry;
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_get_sb(struct file_system_type *fs_type,
|
|
int flags, const char *unused_dev_name,
|
|
void *data, struct vfsmount *mnt)
|
|
{
|
|
struct cgroup_sb_opts opts;
|
|
int ret = 0;
|
|
struct super_block *sb;
|
|
struct cgroupfs_root *root;
|
|
|
|
/* First find the desired set of subsystems */
|
|
ret = parse_cgroupfs_options(data, &opts);
|
|
if (ret)
|
|
return ret;
|
|
|
|
root = kzalloc(sizeof(*root), GFP_KERNEL);
|
|
if (!root)
|
|
return -ENOMEM;
|
|
|
|
init_cgroup_root(root);
|
|
root->subsys_bits = opts.subsys_bits;
|
|
root->flags = opts.flags;
|
|
|
|
sb = sget(fs_type, cgroup_test_super, cgroup_set_super, root);
|
|
|
|
if (IS_ERR(sb)) {
|
|
kfree(root);
|
|
return PTR_ERR(sb);
|
|
}
|
|
|
|
if (sb->s_fs_info != root) {
|
|
/* Reusing an existing superblock */
|
|
BUG_ON(sb->s_root == NULL);
|
|
kfree(root);
|
|
root = NULL;
|
|
} else {
|
|
/* New superblock */
|
|
struct cgroup *cont = &root->top_cgroup;
|
|
|
|
BUG_ON(sb->s_root != NULL);
|
|
|
|
ret = cgroup_get_rootdir(sb);
|
|
if (ret)
|
|
goto drop_new_super;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
ret = rebind_subsystems(root, root->subsys_bits);
|
|
if (ret == -EBUSY) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
goto drop_new_super;
|
|
}
|
|
|
|
/* EBUSY should be the only error here */
|
|
BUG_ON(ret);
|
|
|
|
list_add(&root->root_list, &roots);
|
|
|
|
sb->s_root->d_fsdata = &root->top_cgroup;
|
|
root->top_cgroup.dentry = sb->s_root;
|
|
|
|
BUG_ON(!list_empty(&cont->sibling));
|
|
BUG_ON(!list_empty(&cont->children));
|
|
BUG_ON(root->number_of_cgroups != 1);
|
|
|
|
/*
|
|
* I believe that it's safe to nest i_mutex inside
|
|
* cgroup_mutex in this case, since no-one else can
|
|
* be accessing this directory yet. But we still need
|
|
* to teach lockdep that this is the case - currently
|
|
* a cgroupfs remount triggers a lockdep warning
|
|
*/
|
|
mutex_lock(&cont->dentry->d_inode->i_mutex);
|
|
cgroup_populate_dir(cont);
|
|
mutex_unlock(&cont->dentry->d_inode->i_mutex);
|
|
mutex_unlock(&cgroup_mutex);
|
|
}
|
|
|
|
return simple_set_mnt(mnt, sb);
|
|
|
|
drop_new_super:
|
|
up_write(&sb->s_umount);
|
|
deactivate_super(sb);
|
|
return ret;
|
|
}
|
|
|
|
static void cgroup_kill_sb(struct super_block *sb) {
|
|
struct cgroupfs_root *root = sb->s_fs_info;
|
|
struct cgroup *cont = &root->top_cgroup;
|
|
int ret;
|
|
|
|
BUG_ON(!root);
|
|
|
|
BUG_ON(root->number_of_cgroups != 1);
|
|
BUG_ON(!list_empty(&cont->children));
|
|
BUG_ON(!list_empty(&cont->sibling));
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* Rebind all subsystems back to the default hierarchy */
|
|
ret = rebind_subsystems(root, 0);
|
|
/* Shouldn't be able to fail ... */
|
|
BUG_ON(ret);
|
|
|
|
if (!list_empty(&root->root_list))
|
|
list_del(&root->root_list);
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
kfree(root);
|
|
kill_litter_super(sb);
|
|
}
|
|
|
|
static struct file_system_type cgroup_fs_type = {
|
|
.name = "cgroup",
|
|
.get_sb = cgroup_get_sb,
|
|
.kill_sb = cgroup_kill_sb,
|
|
};
|
|
|
|
static inline struct cgroup *__d_cont(struct dentry *dentry)
|
|
{
|
|
return dentry->d_fsdata;
|
|
}
|
|
|
|
static inline struct cftype *__d_cft(struct dentry *dentry)
|
|
{
|
|
return dentry->d_fsdata;
|
|
}
|
|
|
|
/*
|
|
* Called with cgroup_mutex held. Writes path of cgroup into buf.
|
|
* Returns 0 on success, -errno on error.
|
|
*/
|
|
int cgroup_path(const struct cgroup *cont, char *buf, int buflen)
|
|
{
|
|
char *start;
|
|
|
|
if (cont == dummytop) {
|
|
/*
|
|
* Inactive subsystems have no dentry for their root
|
|
* cgroup
|
|
*/
|
|
strcpy(buf, "/");
|
|
return 0;
|
|
}
|
|
|
|
start = buf + buflen;
|
|
|
|
*--start = '\0';
|
|
for (;;) {
|
|
int len = cont->dentry->d_name.len;
|
|
if ((start -= len) < buf)
|
|
return -ENAMETOOLONG;
|
|
memcpy(start, cont->dentry->d_name.name, len);
|
|
cont = cont->parent;
|
|
if (!cont)
|
|
break;
|
|
if (!cont->parent)
|
|
continue;
|
|
if (--start < buf)
|
|
return -ENAMETOOLONG;
|
|
*start = '/';
|
|
}
|
|
memmove(buf, start, buf + buflen - start);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Return the first subsystem attached to a cgroup's hierarchy, and
|
|
* its subsystem id.
|
|
*/
|
|
|
|
static void get_first_subsys(const struct cgroup *cont,
|
|
struct cgroup_subsys_state **css, int *subsys_id)
|
|
{
|
|
const struct cgroupfs_root *root = cont->root;
|
|
const struct cgroup_subsys *test_ss;
|
|
BUG_ON(list_empty(&root->subsys_list));
|
|
test_ss = list_entry(root->subsys_list.next,
|
|
struct cgroup_subsys, sibling);
|
|
if (css) {
|
|
*css = cont->subsys[test_ss->subsys_id];
|
|
BUG_ON(!*css);
|
|
}
|
|
if (subsys_id)
|
|
*subsys_id = test_ss->subsys_id;
|
|
}
|
|
|
|
/*
|
|
* Attach task 'tsk' to cgroup 'cont'
|
|
*
|
|
* Call holding cgroup_mutex. May take task_lock of
|
|
* the task 'pid' during call.
|
|
*/
|
|
static int attach_task(struct cgroup *cont, struct task_struct *tsk)
|
|
{
|
|
int retval = 0;
|
|
struct cgroup_subsys *ss;
|
|
struct cgroup *oldcont;
|
|
struct css_set *cg = &tsk->cgroups;
|
|
struct cgroupfs_root *root = cont->root;
|
|
int i;
|
|
int subsys_id;
|
|
|
|
get_first_subsys(cont, NULL, &subsys_id);
|
|
|
|
/* Nothing to do if the task is already in that cgroup */
|
|
oldcont = task_cgroup(tsk, subsys_id);
|
|
if (cont == oldcont)
|
|
return 0;
|
|
|
|
for_each_subsys(root, ss) {
|
|
if (ss->can_attach) {
|
|
retval = ss->can_attach(ss, cont, tsk);
|
|
if (retval) {
|
|
return retval;
|
|
}
|
|
}
|
|
}
|
|
|
|
task_lock(tsk);
|
|
if (tsk->flags & PF_EXITING) {
|
|
task_unlock(tsk);
|
|
return -ESRCH;
|
|
}
|
|
/* Update the css_set pointers for the subsystems in this
|
|
* hierarchy */
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
if (root->subsys_bits & (1ull << i)) {
|
|
/* Subsystem is in this hierarchy. So we want
|
|
* the subsystem state from the new
|
|
* cgroup. Transfer the refcount from the
|
|
* old to the new */
|
|
atomic_inc(&cont->count);
|
|
atomic_dec(&cg->subsys[i]->cgroup->count);
|
|
rcu_assign_pointer(cg->subsys[i], cont->subsys[i]);
|
|
}
|
|
}
|
|
task_unlock(tsk);
|
|
|
|
for_each_subsys(root, ss) {
|
|
if (ss->attach) {
|
|
ss->attach(ss, cont, oldcont, tsk);
|
|
}
|
|
}
|
|
|
|
synchronize_rcu();
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Attach task with pid 'pid' to cgroup 'cont'. Call with
|
|
* cgroup_mutex, may take task_lock of task
|
|
*/
|
|
static int attach_task_by_pid(struct cgroup *cont, char *pidbuf)
|
|
{
|
|
pid_t pid;
|
|
struct task_struct *tsk;
|
|
int ret;
|
|
|
|
if (sscanf(pidbuf, "%d", &pid) != 1)
|
|
return -EIO;
|
|
|
|
if (pid) {
|
|
rcu_read_lock();
|
|
tsk = find_task_by_pid(pid);
|
|
if (!tsk || tsk->flags & PF_EXITING) {
|
|
rcu_read_unlock();
|
|
return -ESRCH;
|
|
}
|
|
get_task_struct(tsk);
|
|
rcu_read_unlock();
|
|
|
|
if ((current->euid) && (current->euid != tsk->uid)
|
|
&& (current->euid != tsk->suid)) {
|
|
put_task_struct(tsk);
|
|
return -EACCES;
|
|
}
|
|
} else {
|
|
tsk = current;
|
|
get_task_struct(tsk);
|
|
}
|
|
|
|
ret = attach_task(cont, tsk);
|
|
put_task_struct(tsk);
|
|
return ret;
|
|
}
|
|
|
|
/* The various types of files and directories in a cgroup file system */
|
|
|
|
enum cgroup_filetype {
|
|
FILE_ROOT,
|
|
FILE_DIR,
|
|
FILE_TASKLIST,
|
|
};
|
|
|
|
static ssize_t cgroup_common_file_write(struct cgroup *cont,
|
|
struct cftype *cft,
|
|
struct file *file,
|
|
const char __user *userbuf,
|
|
size_t nbytes, loff_t *unused_ppos)
|
|
{
|
|
enum cgroup_filetype type = cft->private;
|
|
char *buffer;
|
|
int retval = 0;
|
|
|
|
if (nbytes >= PATH_MAX)
|
|
return -E2BIG;
|
|
|
|
/* +1 for nul-terminator */
|
|
buffer = kmalloc(nbytes + 1, GFP_KERNEL);
|
|
if (buffer == NULL)
|
|
return -ENOMEM;
|
|
|
|
if (copy_from_user(buffer, userbuf, nbytes)) {
|
|
retval = -EFAULT;
|
|
goto out1;
|
|
}
|
|
buffer[nbytes] = 0; /* nul-terminate */
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
if (cgroup_is_removed(cont)) {
|
|
retval = -ENODEV;
|
|
goto out2;
|
|
}
|
|
|
|
switch (type) {
|
|
case FILE_TASKLIST:
|
|
retval = attach_task_by_pid(cont, buffer);
|
|
break;
|
|
default:
|
|
retval = -EINVAL;
|
|
goto out2;
|
|
}
|
|
|
|
if (retval == 0)
|
|
retval = nbytes;
|
|
out2:
|
|
mutex_unlock(&cgroup_mutex);
|
|
out1:
|
|
kfree(buffer);
|
|
return retval;
|
|
}
|
|
|
|
static ssize_t cgroup_file_write(struct file *file, const char __user *buf,
|
|
size_t nbytes, loff_t *ppos)
|
|
{
|
|
struct cftype *cft = __d_cft(file->f_dentry);
|
|
struct cgroup *cont = __d_cont(file->f_dentry->d_parent);
|
|
|
|
if (!cft)
|
|
return -ENODEV;
|
|
if (!cft->write)
|
|
return -EINVAL;
|
|
|
|
return cft->write(cont, cft, file, buf, nbytes, ppos);
|
|
}
|
|
|
|
static ssize_t cgroup_read_uint(struct cgroup *cont, struct cftype *cft,
|
|
struct file *file,
|
|
char __user *buf, size_t nbytes,
|
|
loff_t *ppos)
|
|
{
|
|
char tmp[64];
|
|
u64 val = cft->read_uint(cont, cft);
|
|
int len = sprintf(tmp, "%llu\n", (unsigned long long) val);
|
|
|
|
return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
|
|
}
|
|
|
|
static ssize_t cgroup_file_read(struct file *file, char __user *buf,
|
|
size_t nbytes, loff_t *ppos)
|
|
{
|
|
struct cftype *cft = __d_cft(file->f_dentry);
|
|
struct cgroup *cont = __d_cont(file->f_dentry->d_parent);
|
|
|
|
if (!cft)
|
|
return -ENODEV;
|
|
|
|
if (cft->read)
|
|
return cft->read(cont, cft, file, buf, nbytes, ppos);
|
|
if (cft->read_uint)
|
|
return cgroup_read_uint(cont, cft, file, buf, nbytes, ppos);
|
|
return -EINVAL;
|
|
}
|
|
|
|
static int cgroup_file_open(struct inode *inode, struct file *file)
|
|
{
|
|
int err;
|
|
struct cftype *cft;
|
|
|
|
err = generic_file_open(inode, file);
|
|
if (err)
|
|
return err;
|
|
|
|
cft = __d_cft(file->f_dentry);
|
|
if (!cft)
|
|
return -ENODEV;
|
|
if (cft->open)
|
|
err = cft->open(inode, file);
|
|
else
|
|
err = 0;
|
|
|
|
return err;
|
|
}
|
|
|
|
static int cgroup_file_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct cftype *cft = __d_cft(file->f_dentry);
|
|
if (cft->release)
|
|
return cft->release(inode, file);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* cgroup_rename - Only allow simple rename of directories in place.
|
|
*/
|
|
static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry)
|
|
{
|
|
if (!S_ISDIR(old_dentry->d_inode->i_mode))
|
|
return -ENOTDIR;
|
|
if (new_dentry->d_inode)
|
|
return -EEXIST;
|
|
if (old_dir != new_dir)
|
|
return -EIO;
|
|
return simple_rename(old_dir, old_dentry, new_dir, new_dentry);
|
|
}
|
|
|
|
static struct file_operations cgroup_file_operations = {
|
|
.read = cgroup_file_read,
|
|
.write = cgroup_file_write,
|
|
.llseek = generic_file_llseek,
|
|
.open = cgroup_file_open,
|
|
.release = cgroup_file_release,
|
|
};
|
|
|
|
static struct inode_operations cgroup_dir_inode_operations = {
|
|
.lookup = simple_lookup,
|
|
.mkdir = cgroup_mkdir,
|
|
.rmdir = cgroup_rmdir,
|
|
.rename = cgroup_rename,
|
|
};
|
|
|
|
static int cgroup_create_file(struct dentry *dentry, int mode,
|
|
struct super_block *sb)
|
|
{
|
|
static struct dentry_operations cgroup_dops = {
|
|
.d_iput = cgroup_diput,
|
|
};
|
|
|
|
struct inode *inode;
|
|
|
|
if (!dentry)
|
|
return -ENOENT;
|
|
if (dentry->d_inode)
|
|
return -EEXIST;
|
|
|
|
inode = cgroup_new_inode(mode, sb);
|
|
if (!inode)
|
|
return -ENOMEM;
|
|
|
|
if (S_ISDIR(mode)) {
|
|
inode->i_op = &cgroup_dir_inode_operations;
|
|
inode->i_fop = &simple_dir_operations;
|
|
|
|
/* start off with i_nlink == 2 (for "." entry) */
|
|
inc_nlink(inode);
|
|
|
|
/* start with the directory inode held, so that we can
|
|
* populate it without racing with another mkdir */
|
|
mutex_lock(&inode->i_mutex);
|
|
} else if (S_ISREG(mode)) {
|
|
inode->i_size = 0;
|
|
inode->i_fop = &cgroup_file_operations;
|
|
}
|
|
dentry->d_op = &cgroup_dops;
|
|
d_instantiate(dentry, inode);
|
|
dget(dentry); /* Extra count - pin the dentry in core */
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* cgroup_create_dir - create a directory for an object.
|
|
* cont: the cgroup we create the directory for.
|
|
* It must have a valid ->parent field
|
|
* And we are going to fill its ->dentry field.
|
|
* dentry: dentry of the new container
|
|
* mode: mode to set on new directory.
|
|
*/
|
|
static int cgroup_create_dir(struct cgroup *cont, struct dentry *dentry,
|
|
int mode)
|
|
{
|
|
struct dentry *parent;
|
|
int error = 0;
|
|
|
|
parent = cont->parent->dentry;
|
|
error = cgroup_create_file(dentry, S_IFDIR | mode, cont->root->sb);
|
|
if (!error) {
|
|
dentry->d_fsdata = cont;
|
|
inc_nlink(parent->d_inode);
|
|
cont->dentry = dentry;
|
|
dget(dentry);
|
|
}
|
|
dput(dentry);
|
|
|
|
return error;
|
|
}
|
|
|
|
int cgroup_add_file(struct cgroup *cont,
|
|
struct cgroup_subsys *subsys,
|
|
const struct cftype *cft)
|
|
{
|
|
struct dentry *dir = cont->dentry;
|
|
struct dentry *dentry;
|
|
int error;
|
|
|
|
char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
|
|
if (subsys && !test_bit(ROOT_NOPREFIX, &cont->root->flags)) {
|
|
strcpy(name, subsys->name);
|
|
strcat(name, ".");
|
|
}
|
|
strcat(name, cft->name);
|
|
BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));
|
|
dentry = lookup_one_len(name, dir, strlen(name));
|
|
if (!IS_ERR(dentry)) {
|
|
error = cgroup_create_file(dentry, 0644 | S_IFREG,
|
|
cont->root->sb);
|
|
if (!error)
|
|
dentry->d_fsdata = (void *)cft;
|
|
dput(dentry);
|
|
} else
|
|
error = PTR_ERR(dentry);
|
|
return error;
|
|
}
|
|
|
|
int cgroup_add_files(struct cgroup *cont,
|
|
struct cgroup_subsys *subsys,
|
|
const struct cftype cft[],
|
|
int count)
|
|
{
|
|
int i, err;
|
|
for (i = 0; i < count; i++) {
|
|
err = cgroup_add_file(cont, subsys, &cft[i]);
|
|
if (err)
|
|
return err;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Count the number of tasks in a cgroup. Could be made more
|
|
* time-efficient but less space-efficient with more linked lists
|
|
* running through each cgroup and the css_set structures that
|
|
* referenced it. Must be called with tasklist_lock held for read or
|
|
* write or in an rcu critical section.
|
|
*/
|
|
int __cgroup_task_count(const struct cgroup *cont)
|
|
{
|
|
int count = 0;
|
|
struct task_struct *g, *p;
|
|
struct cgroup_subsys_state *css;
|
|
int subsys_id;
|
|
|
|
get_first_subsys(cont, &css, &subsys_id);
|
|
do_each_thread(g, p) {
|
|
if (task_subsys_state(p, subsys_id) == css)
|
|
count ++;
|
|
} while_each_thread(g, p);
|
|
return count;
|
|
}
|
|
|
|
/*
|
|
* Stuff for reading the 'tasks' file.
|
|
*
|
|
* Reading this file can return large amounts of data if a cgroup has
|
|
* *lots* of attached tasks. So it may need several calls to read(),
|
|
* but we cannot guarantee that the information we produce is correct
|
|
* unless we produce it entirely atomically.
|
|
*
|
|
* Upon tasks file open(), a struct ctr_struct is allocated, that
|
|
* will have a pointer to an array (also allocated here). The struct
|
|
* ctr_struct * is stored in file->private_data. Its resources will
|
|
* be freed by release() when the file is closed. The array is used
|
|
* to sprintf the PIDs and then used by read().
|
|
*/
|
|
struct ctr_struct {
|
|
char *buf;
|
|
int bufsz;
|
|
};
|
|
|
|
/*
|
|
* Load into 'pidarray' up to 'npids' of the tasks using cgroup
|
|
* 'cont'. Return actual number of pids loaded. No need to
|
|
* task_lock(p) when reading out p->cgroup, since we're in an RCU
|
|
* read section, so the css_set can't go away, and is
|
|
* immutable after creation.
|
|
*/
|
|
static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cont)
|
|
{
|
|
int n = 0;
|
|
struct task_struct *g, *p;
|
|
struct cgroup_subsys_state *css;
|
|
int subsys_id;
|
|
|
|
get_first_subsys(cont, &css, &subsys_id);
|
|
rcu_read_lock();
|
|
do_each_thread(g, p) {
|
|
if (task_subsys_state(p, subsys_id) == css) {
|
|
pidarray[n++] = pid_nr(task_pid(p));
|
|
if (unlikely(n == npids))
|
|
goto array_full;
|
|
}
|
|
} while_each_thread(g, p);
|
|
|
|
array_full:
|
|
rcu_read_unlock();
|
|
return n;
|
|
}
|
|
|
|
static int cmppid(const void *a, const void *b)
|
|
{
|
|
return *(pid_t *)a - *(pid_t *)b;
|
|
}
|
|
|
|
/*
|
|
* Convert array 'a' of 'npids' pid_t's to a string of newline separated
|
|
* decimal pids in 'buf'. Don't write more than 'sz' chars, but return
|
|
* count 'cnt' of how many chars would be written if buf were large enough.
|
|
*/
|
|
static int pid_array_to_buf(char *buf, int sz, pid_t *a, int npids)
|
|
{
|
|
int cnt = 0;
|
|
int i;
|
|
|
|
for (i = 0; i < npids; i++)
|
|
cnt += snprintf(buf + cnt, max(sz - cnt, 0), "%d\n", a[i]);
|
|
return cnt;
|
|
}
|
|
|
|
/*
|
|
* Handle an open on 'tasks' file. Prepare a buffer listing the
|
|
* process id's of tasks currently attached to the cgroup being opened.
|
|
*
|
|
* Does not require any specific cgroup mutexes, and does not take any.
|
|
*/
|
|
static int cgroup_tasks_open(struct inode *unused, struct file *file)
|
|
{
|
|
struct cgroup *cont = __d_cont(file->f_dentry->d_parent);
|
|
struct ctr_struct *ctr;
|
|
pid_t *pidarray;
|
|
int npids;
|
|
char c;
|
|
|
|
if (!(file->f_mode & FMODE_READ))
|
|
return 0;
|
|
|
|
ctr = kmalloc(sizeof(*ctr), GFP_KERNEL);
|
|
if (!ctr)
|
|
goto err0;
|
|
|
|
/*
|
|
* If cgroup gets more users after we read count, we won't have
|
|
* enough space - tough. This race is indistinguishable to the
|
|
* caller from the case that the additional cgroup users didn't
|
|
* show up until sometime later on.
|
|
*/
|
|
npids = cgroup_task_count(cont);
|
|
if (npids) {
|
|
pidarray = kmalloc(npids * sizeof(pid_t), GFP_KERNEL);
|
|
if (!pidarray)
|
|
goto err1;
|
|
|
|
npids = pid_array_load(pidarray, npids, cont);
|
|
sort(pidarray, npids, sizeof(pid_t), cmppid, NULL);
|
|
|
|
/* Call pid_array_to_buf() twice, first just to get bufsz */
|
|
ctr->bufsz = pid_array_to_buf(&c, sizeof(c), pidarray, npids) + 1;
|
|
ctr->buf = kmalloc(ctr->bufsz, GFP_KERNEL);
|
|
if (!ctr->buf)
|
|
goto err2;
|
|
ctr->bufsz = pid_array_to_buf(ctr->buf, ctr->bufsz, pidarray, npids);
|
|
|
|
kfree(pidarray);
|
|
} else {
|
|
ctr->buf = 0;
|
|
ctr->bufsz = 0;
|
|
}
|
|
file->private_data = ctr;
|
|
return 0;
|
|
|
|
err2:
|
|
kfree(pidarray);
|
|
err1:
|
|
kfree(ctr);
|
|
err0:
|
|
return -ENOMEM;
|
|
}
|
|
|
|
static ssize_t cgroup_tasks_read(struct cgroup *cont,
|
|
struct cftype *cft,
|
|
struct file *file, char __user *buf,
|
|
size_t nbytes, loff_t *ppos)
|
|
{
|
|
struct ctr_struct *ctr = file->private_data;
|
|
|
|
return simple_read_from_buffer(buf, nbytes, ppos, ctr->buf, ctr->bufsz);
|
|
}
|
|
|
|
static int cgroup_tasks_release(struct inode *unused_inode,
|
|
struct file *file)
|
|
{
|
|
struct ctr_struct *ctr;
|
|
|
|
if (file->f_mode & FMODE_READ) {
|
|
ctr = file->private_data;
|
|
kfree(ctr->buf);
|
|
kfree(ctr);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* for the common functions, 'private' gives the type of file
|
|
*/
|
|
static struct cftype cft_tasks = {
|
|
.name = "tasks",
|
|
.open = cgroup_tasks_open,
|
|
.read = cgroup_tasks_read,
|
|
.write = cgroup_common_file_write,
|
|
.release = cgroup_tasks_release,
|
|
.private = FILE_TASKLIST,
|
|
};
|
|
|
|
static int cgroup_populate_dir(struct cgroup *cont)
|
|
{
|
|
int err;
|
|
struct cgroup_subsys *ss;
|
|
|
|
/* First clear out any existing files */
|
|
cgroup_clear_directory(cont->dentry);
|
|
|
|
err = cgroup_add_file(cont, NULL, &cft_tasks);
|
|
if (err < 0)
|
|
return err;
|
|
|
|
for_each_subsys(cont->root, ss) {
|
|
if (ss->populate && (err = ss->populate(ss, cont)) < 0)
|
|
return err;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void init_cgroup_css(struct cgroup_subsys_state *css,
|
|
struct cgroup_subsys *ss,
|
|
struct cgroup *cont)
|
|
{
|
|
css->cgroup = cont;
|
|
atomic_set(&css->refcnt, 0);
|
|
css->flags = 0;
|
|
if (cont == dummytop)
|
|
set_bit(CSS_ROOT, &css->flags);
|
|
BUG_ON(cont->subsys[ss->subsys_id]);
|
|
cont->subsys[ss->subsys_id] = css;
|
|
}
|
|
|
|
/*
|
|
* cgroup_create - create a cgroup
|
|
* parent: cgroup that will be parent of the new cgroup.
|
|
* name: name of the new cgroup. Will be strcpy'ed.
|
|
* mode: mode to set on new inode
|
|
*
|
|
* Must be called with the mutex on the parent inode held
|
|
*/
|
|
|
|
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
|
|
int mode)
|
|
{
|
|
struct cgroup *cont;
|
|
struct cgroupfs_root *root = parent->root;
|
|
int err = 0;
|
|
struct cgroup_subsys *ss;
|
|
struct super_block *sb = root->sb;
|
|
|
|
cont = kzalloc(sizeof(*cont), GFP_KERNEL);
|
|
if (!cont)
|
|
return -ENOMEM;
|
|
|
|
/* Grab a reference on the superblock so the hierarchy doesn't
|
|
* get deleted on unmount if there are child cgroups. This
|
|
* can be done outside cgroup_mutex, since the sb can't
|
|
* disappear while someone has an open control file on the
|
|
* fs */
|
|
atomic_inc(&sb->s_active);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
cont->flags = 0;
|
|
INIT_LIST_HEAD(&cont->sibling);
|
|
INIT_LIST_HEAD(&cont->children);
|
|
|
|
cont->parent = parent;
|
|
cont->root = parent->root;
|
|
cont->top_cgroup = parent->top_cgroup;
|
|
|
|
for_each_subsys(root, ss) {
|
|
struct cgroup_subsys_state *css = ss->create(ss, cont);
|
|
if (IS_ERR(css)) {
|
|
err = PTR_ERR(css);
|
|
goto err_destroy;
|
|
}
|
|
init_cgroup_css(css, ss, cont);
|
|
}
|
|
|
|
list_add(&cont->sibling, &cont->parent->children);
|
|
root->number_of_cgroups++;
|
|
|
|
err = cgroup_create_dir(cont, dentry, mode);
|
|
if (err < 0)
|
|
goto err_remove;
|
|
|
|
/* The cgroup directory was pre-locked for us */
|
|
BUG_ON(!mutex_is_locked(&cont->dentry->d_inode->i_mutex));
|
|
|
|
err = cgroup_populate_dir(cont);
|
|
/* If err < 0, we have a half-filled directory - oh well ;) */
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cont->dentry->d_inode->i_mutex);
|
|
|
|
return 0;
|
|
|
|
err_remove:
|
|
|
|
list_del(&cont->sibling);
|
|
root->number_of_cgroups--;
|
|
|
|
err_destroy:
|
|
|
|
for_each_subsys(root, ss) {
|
|
if (cont->subsys[ss->subsys_id])
|
|
ss->destroy(ss, cont);
|
|
}
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
/* Release the reference count that we took on the superblock */
|
|
deactivate_super(sb);
|
|
|
|
kfree(cont);
|
|
return err;
|
|
}
|
|
|
|
static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode)
|
|
{
|
|
struct cgroup *c_parent = dentry->d_parent->d_fsdata;
|
|
|
|
/* the vfs holds inode->i_mutex already */
|
|
return cgroup_create(c_parent, dentry, mode | S_IFDIR);
|
|
}
|
|
|
|
static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
|
|
{
|
|
struct cgroup *cont = dentry->d_fsdata;
|
|
struct dentry *d;
|
|
struct cgroup *parent;
|
|
struct cgroup_subsys *ss;
|
|
struct super_block *sb;
|
|
struct cgroupfs_root *root;
|
|
int css_busy = 0;
|
|
|
|
/* the vfs holds both inode->i_mutex already */
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
if (atomic_read(&cont->count) != 0) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
return -EBUSY;
|
|
}
|
|
if (!list_empty(&cont->children)) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
return -EBUSY;
|
|
}
|
|
|
|
parent = cont->parent;
|
|
root = cont->root;
|
|
sb = root->sb;
|
|
|
|
/* Check the reference count on each subsystem. Since we
|
|
* already established that there are no tasks in the
|
|
* cgroup, if the css refcount is also 0, then there should
|
|
* be no outstanding references, so the subsystem is safe to
|
|
* destroy */
|
|
for_each_subsys(root, ss) {
|
|
struct cgroup_subsys_state *css;
|
|
css = cont->subsys[ss->subsys_id];
|
|
if (atomic_read(&css->refcnt)) {
|
|
css_busy = 1;
|
|
break;
|
|
}
|
|
}
|
|
if (css_busy) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
return -EBUSY;
|
|
}
|
|
|
|
for_each_subsys(root, ss) {
|
|
if (cont->subsys[ss->subsys_id])
|
|
ss->destroy(ss, cont);
|
|
}
|
|
|
|
set_bit(CONT_REMOVED, &cont->flags);
|
|
/* delete my sibling from parent->children */
|
|
list_del(&cont->sibling);
|
|
spin_lock(&cont->dentry->d_lock);
|
|
d = dget(cont->dentry);
|
|
cont->dentry = NULL;
|
|
spin_unlock(&d->d_lock);
|
|
|
|
cgroup_d_remove_dir(d);
|
|
dput(d);
|
|
root->number_of_cgroups--;
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
/* Drop the active superblock reference that we took when we
|
|
* created the cgroup */
|
|
deactivate_super(sb);
|
|
return 0;
|
|
}
|
|
|
|
static void cgroup_init_subsys(struct cgroup_subsys *ss)
|
|
{
|
|
struct task_struct *g, *p;
|
|
struct cgroup_subsys_state *css;
|
|
printk(KERN_ERR "Initializing cgroup subsys %s\n", ss->name);
|
|
|
|
/* Create the top cgroup state for this subsystem */
|
|
ss->root = &rootnode;
|
|
css = ss->create(ss, dummytop);
|
|
/* We don't handle early failures gracefully */
|
|
BUG_ON(IS_ERR(css));
|
|
init_cgroup_css(css, ss, dummytop);
|
|
|
|
/* Update all tasks to contain a subsys pointer to this state
|
|
* - since the subsystem is newly registered, all tasks are in
|
|
* the subsystem's top cgroup. */
|
|
|
|
/* If this subsystem requested that it be notified with fork
|
|
* events, we should send it one now for every process in the
|
|
* system */
|
|
|
|
read_lock(&tasklist_lock);
|
|
init_task.cgroups.subsys[ss->subsys_id] = css;
|
|
if (ss->fork)
|
|
ss->fork(ss, &init_task);
|
|
|
|
do_each_thread(g, p) {
|
|
printk(KERN_INFO "Setting task %p css to %p (%d)\n", css, p, p->pid);
|
|
p->cgroups.subsys[ss->subsys_id] = css;
|
|
if (ss->fork)
|
|
ss->fork(ss, p);
|
|
} while_each_thread(g, p);
|
|
read_unlock(&tasklist_lock);
|
|
|
|
need_forkexit_callback |= ss->fork || ss->exit;
|
|
|
|
ss->active = 1;
|
|
}
|
|
|
|
/**
|
|
* cgroup_init_early - initialize cgroups at system boot, and
|
|
* initialize any subsystems that request early init.
|
|
*/
|
|
int __init cgroup_init_early(void)
|
|
{
|
|
int i;
|
|
init_cgroup_root(&rootnode);
|
|
list_add(&rootnode.root_list, &roots);
|
|
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
|
|
BUG_ON(!ss->name);
|
|
BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
|
|
BUG_ON(!ss->create);
|
|
BUG_ON(!ss->destroy);
|
|
if (ss->subsys_id != i) {
|
|
printk(KERN_ERR "Subsys %s id == %d\n",
|
|
ss->name, ss->subsys_id);
|
|
BUG();
|
|
}
|
|
|
|
if (ss->early_init)
|
|
cgroup_init_subsys(ss);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_init - register cgroup filesystem and /proc file, and
|
|
* initialize any subsystems that didn't request early init.
|
|
*/
|
|
int __init cgroup_init(void)
|
|
{
|
|
int err;
|
|
int i;
|
|
|
|
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
|
|
struct cgroup_subsys *ss = subsys[i];
|
|
if (!ss->early_init)
|
|
cgroup_init_subsys(ss);
|
|
}
|
|
|
|
err = register_filesystem(&cgroup_fs_type);
|
|
if (err < 0)
|
|
goto out;
|
|
|
|
out:
|
|
return err;
|
|
}
|