[PATCH 1/2] rcfs core patch

Srivatsa Vaddagiri
2007-03-01T13:45:35Z

Heavily based on Paul Menage's (inturn cpuset) work. The big difference
is that the patch uses task->nsproxy to group tasks for resource control
purpose (instead of task->containers).

The patch retains the same user interface as Paul Menage's patches. In
particular, you can have multiple hierarchies, each hierarchy giving a
different composition/view of task-groups.

(Ideally this patch should have been split into 2 or 3 sub-patches, but
will do that on a subsequent version post)

Signed-off-by : Srivatsa Vaddagiri <vatsa@in.ibm.com>
Signed-off-by : Paul Menage <menage@google.com>

---

linux-2.6.20-vatsa/include/linux/init_task.h | 4
linux-2.6.20-vatsa/include/linux/nsproxy.h | 5
linux-2.6.20-vatsa/init/Kconfig | 22
linux-2.6.20-vatsa/init/main.c | 1
linux-2.6.20-vatsa/kernel/Makefile | 1

---

diff -puN include/linux/init_task.h~rcfs include/linux/init_task.h
--- linux-2.6.20/include/linux/init_task.h~rcfs 2007-03-01 14:20:47.000000000 +0530
+++ linux-2.6.20-vatsa/include/linux/init_task.h 2007-03-01 14:20:47.000000000 +0530
@@ -71,6 +71,16 @@
}

extern struct nsproxy init_nsproxy;
+
+#ifdef CONFIG_RCFS
+#define INIT_RCFS(nsproxy) \
+ .list = LIST_HEAD_INIT(nsproxy.list), \
+ .ctlr_data = {[ 0 ... CONFIG_MAX_RC_SUBSYS-1 ] = NULL },
+#else
+#define INIT_RCFS(nsproxy)
+#endif
+
+
#define INIT_NSPROXY(nsproxy) { \
.pid_ns = &init_pid_ns, \
.count = ATOMIC_INIT(1), \
@@ -78,6 +88,7 @@ extern struct nsproxy init_nsproxy;
.uts_ns = &init_uts_ns, \
.mnt_ns = NULL, \
INIT_IPC_NS(ipc_ns) \
+ INIT_RCFS(nsproxy) \
}

#define INIT_SIGHAND(sighand) { \
diff -puN include/linux/nsproxy.h~rcfs include/linux/nsproxy.h
--- linux-2.6.20/include/linux/nsproxy.h~rcfs 2007-03-01 14:20:47.000000000 +0530
+++ linux-2.6.20-vatsa/include/linux/nsproxy.h 2007-03-01 14:20:47.000000000 +0530
@@ -28,6 +28,10 @@ struct nsproxy {
struct ipc_namespace *ipc_ns;
struct mnt_namespace *mnt_ns;
struct pid_namespace *pid_ns;
+#ifdef CONFIG_RCFS
+ struct list_head list;
+ void *ctlr_data[CONFIG_MAX_RC_SUBSYS];
+#endif
};
extern struct nsproxy init_nsproxy;

@@ -35,6 +39,12 @@ struct nsproxy *dup_namespaces(struct ns
int copy_namespaces(int flags, struct task_struct *tsk);
void get_task_namespaces(struct task_struct *tsk);
void free_nsproxy(struct nsproxy *ns);
+#ifdef CONFIG_RCFS
+struct nsproxy *find_nsproxy(struct nsproxy *ns);
+int namespaces_init(void);
+#else
+static inline int namespaces_init(void) { return 0;}
+#endif

static inline void put_nsproxy(struct nsproxy *ns)
{
diff -puN /dev/null include/linux/rcfs.h
--- /dev/null 2006-02-25 03:06:56.000000000 +0530
+++ linux-2.6.20-vatsa/include/linux/rcfs.h 2007-03-01 14:20:47.000000000 +0530
@@ -0,0 +1,72 @@
+#ifndef _LINUX_RCFS_H
+#define _LINUX_RCFS_H
+
+#ifdef CONFIG_RCFS
+
+/* struct cftype:
+ *
+ * The files in the container filesystem mostly have a very simple read/write
+ * handling, some common function will take care of it. Nevertheless some cases
+ * (read tasks) are special and therefore I define this structure for every
+ * kind of file.
+ *
+ *
+ * When reading/writing to a file:
+ * - the container to use in file->f_dentry->d_parent->d_fsdata
+ * - the 'cftype' of the file is file->f_dentry->d_fsdata
+ */
+
+struct inode;
+#define MAX_CFTYPE_NAME 64
+struct cftype {
+ /* By convention, the name should begin with the name of the
+ * subsystem, followed by a period */
+ char name[MAX_CFTYPE_NAME];
+ int private;
+ int (*open) (struct inode *inode, struct file *file);
+ ssize_t (*read) (struct nsproxy *ns, struct cftype *cft,
+ struct file *file,
+ char __user *buf, size_t nbytes, loff_t *ppos);
+ ssize_t (*write) (struct nsproxy *ns, struct cftype *cft,
+ struct file *file,
+ const char __user *buf, size_t nbytes, loff_t *ppos);
+ int (*release) (struct inode *inode, struct file *file);
+};
+
+/* resource control subsystem type. See Documentation/rcfs.txt for details */
+
+struct rc_subsys {
+ int (*create)(struct rc_subsys *ss, struct nsproxy *ns,
+ struct nsproxy *parent);
+ void (*destroy)(struct rc_subsys *ss, struct nsproxy *ns);
+ int (*can_attach)(struct rc_subsys *ss, struct nsproxy *ns,
+ struct task_struct *tsk);
+ void (*attach)(struct rc_subsys *ss, void *new, void *old,
+ struct task_struct *tsk);
+ int (*populate)(struct rc_subsys *ss, struct dentry *d);
+ int subsys_id;
+ int active;
+
+#define MAX_CONTAINER_TYPE_NAMELEN 32
+ const char *name;
+
+ /* Protected by RCU */
+ int hierarchy;
+
+ struct list_head sibling;
+};
+
+int rc_register_subsys(struct rc_subsys *subsys);
+/* Add a new file to the given container directory. Should only be
+ * called by subsystems from within a populate() method */
+int rcfs_add_file(struct dentry *d, const struct cftype *cft);
+extern int rcfs_init(void);
+
+#else
+
+static inline int rcfs_init(void) { return 0; }
+
+#endif
+
+
+#endif
diff -puN init/Kconfig~rcfs init/Kconfig
--- linux-2.6.20/init/Kconfig~rcfs 2007-03-01 14:20:47.000000000 +0530
+++ linux-2.6.20-vatsa/init/Kconfig 2007-03-01 16:52:50.000000000 +0530
@@ -238,6 +238,28 @@ config IKCONFIG_PROC
This option enables access to the kernel configuration file
through /proc/config.gz.

+config RCFS
+ bool "Resource control file system support"
+ default n
+ help
+ This option will let you create and manage resource containers,
+ which can be used to aggregate multiple processes, e.g. for
+ the purposes of resource tracking.
+
+ Say N if unsure
+
+config MAX_RC_SUBSYS
+ int "Number of resource control subsystems to support"
+ depends on RCFS
+ range 1 255
+ default 8
+
+config MAX_RC_HIERARCHIES
+ int "Number of rcfs hierarchies to support"
+ depends on RCFS
+ range 2 255
+ default 4
+
config CPUSETS
bool "Cpuset support"
depends on SMP
diff -puN init/main.c~rcfs init/main.c
--- linux-2.6.20/init/main.c~rcfs 2007-03-01 14:20:47.000000000 +0530
+++ linux-2.6.20-vatsa/init/main.c 2007-03-01 14:20:47.000000000 +0530
@@ -52,6 +52,7 @@
#include <linux/lockdep.h>
#include <linux/pid_namespace.h>
#include <linux/device.h>
+#include <linux/rcfs.h>

#include <asm/io.h>
#include <asm/bugs.h>
@@ -512,6 +513,7 @@ asmlinkage void __init start_kernel(void
setup_per_cpu_areas();
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */

+ namespaces_init();
/*
* Set up the scheduler prior starting any interrupts (such as the
* timer interrupt). Full topology setup happens at smp_init()
@@ -608,6 +610,7 @@ asmlinkage void __init start_kernel(void
#ifdef CONFIG_PROC_FS
proc_root_init();
#endif
+ rcfs_init();
cpuset_init();
taskstats_init_early();
delayacct_init();
diff -puN kernel/Makefile~rcfs kernel/Makefile
--- linux-2.6.20/kernel/Makefile~rcfs 2007-03-01 14:20:47.000000000 +0530
+++ linux-2.6.20-vatsa/kernel/Makefile 2007-03-01 16:52:50.000000000 +0530
@@ -50,6 +50,7 @@ obj-$(CONFIG_RELAY) += relay.o
obj-$(CONFIG_UTS_NS) += utsname.o
obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
+obj-$(CONFIG_RCFS) += rcfs.o

ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
diff -puN kernel/nsproxy.c~rcfs kernel/nsproxy.c
--- linux-2.6.20/kernel/nsproxy.c~rcfs 2007-03-01 14:20:47.000000000 +0530
+++ linux-2.6.20-vatsa/kernel/nsproxy.c 2007-03-01 14:20:47.000000000 +0530
@@ -23,6 +23,11 @@

struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);

+#ifdef CONFIG_RCFS
+static LIST_HEAD(nslisthead);
+static DEFINE_SPINLOCK(nslistlock);
+#endif
+
static inline void get_nsproxy(struct nsproxy *ns)
{
atomic_inc(&ns->count);
@@ -71,6 +76,12 @@ struct nsproxy *dup_namespaces(struct ns
get_pid_ns(ns->pid_ns);
}

+#ifdef CONFIG_RCFS
+ spin_lock(&nslistlock);
+ list_add(&ns->list, &nslisthead);
+ spin_unlock(&nslistlock);
+#endif
+
return ns;
}

@@ -145,5 +156,44 @@ void free_nsproxy(struct nsproxy *ns)
put_ipc_ns(ns->ipc_ns);
if (ns->pid_ns)
put_pid_ns(ns->pid_ns);
+#ifdef CONFIG_RCFS
+ spin_lock(&nslistlock);
+ list_del(&ns->list);
+ spin_unlock(&nslistlock);
+#endif
kfree(ns);
}
+
+#ifdef CONFIG_RCFS
+struct nsproxy *find_nsproxy(struct nsproxy *target)
+{
+ struct nsproxy *ns;
+ int i = 0;
+
+ spin_lock(&nslistlock);
+ list_for_each_entry(ns, &nslisthead, list) {
+ for (i= 0; i < CONFIG_MAX_RC_SUBSYS; ++i)
+ if (ns->ctlr_data[i] != target->ctlr_data[i])
+ break;
+
+ if (i == CONFIG_MAX_RC_SUBSYS) {
+ /* Found a hit */
+ get_nsproxy(ns);
+ spin_unlock(&nslistlock);
+ return ns;
+ }
+ }
+
+ spin_unlock(&nslistlock);
+
+ ns = dup_namespaces(target);
+ return ns;
+}
+
+int __init namespaces_init(void)
+{
+ list_add(&init_nsproxy.list, &nslisthead);
+
+ return 0;
+}
+#endif
diff -puN /dev/null kernel/rcfs.c
--- /dev/null 2006-02-25 03:06:56.000000000 +0530
+++ linux-2.6.20-vatsa/kernel/rcfs.c 2007-03-01 16:53:24.000000000 +0530
@@ -0,0 +1,1138 @@
+/*
+ * kernel/rcfs.c
+ *
+ * Generic resource container system.
+ *
+ * Based originally on the cpuset system, extracted by Paul Menage
+ * Copyright (C) 2006 Google, Inc
+ *
+ * Copyright notices from the original cpuset code:
+ * --------------------------------------------------
+ * Copyright (C) 2003 BULL SA.
+ * Copyright (C) 2004-2006 Silicon Graphics, Inc.
+ *
+ * Portions derived from Patrick Mochel's sysfs code.
+ * sysfs is Copyright (c) 2001-3 Patrick Mochel
+ *
+ * 2003-10-10 Written by Simon Derr.
+ * 2003-10-22 Updates by Stephen Hemminger.
+ * 2004 May-July Rework by Paul Jackson.
+ * ---------------------------------------------------
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/kmod.h>
+#include <linux/list.h>
+#include <linux/mempolicy.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/pagemap.h>
+#include <linux/proc_fs.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+#include <linux/security.h>
+#include <linux/slab.h>
+#include <linux/smp_lock.h>
+#include <linux/spinlock.h>
+#include <linux/stat.h>
+#include <linux/string.h>
+#include <linux/time.h>
+#include <linux/backing-dev.h>
+#include <linux/sort.h>
+#include <linux/nsproxy.h>
+#include <linux/rcfs.h>
+
+#include <asm/uaccess.h>
+#include <asm/atomic.h>
+#include <linux/mutex.h>
+
+#define RCFS_SUPER_MAGIC 0x27e0eb
+
+/* A rcfs_root represents the root of a resource control hierarchy,
+ * and may be associated with a superblock to form an active
+ * hierarchy */
+struct rcfs_root {
+ struct super_block *sb;
+
+ /* The bitmask of subsystems attached to this hierarchy */
+ unsigned long subsys_bits;
+
+ /* A list running through the attached subsystems */
+ struct list_head subsys_list;
+};
+
+static DEFINE_MUTEX(manage_mutex);
+
+/* The set of hierarchies in use */
+static struct rcfs_root rootnode[CONFIG_MAX_RC_HIERARCHIES];
+
+static struct rc_subsys *subsys[CONFIG_MAX_RC_SUBSYS];
+static int subsys_count = 0;
+
+/* for_each_subsys() allows you to act on each subsystem attached to
+ * an active hierarchy */
+#define for_each_subsys(root, _ss) \
+list_for_each_entry(_ss, &root->subsys_list, sibling)
+
+/* Does a container directory have sub-directories under it ? */
+static int dir_empty(struct dentry *dentry)
+{
+ struct dentry *d;
+ int rc = 1;
+
+ spin_lock(&dcache_lock);
+ list_for_each_entry(d, &dentry->d_subdirs, d_u.d_child) {
+ if (S_ISDIR(d->d_inode->i_mode)) {
+ rc = 0;
+ break;
+ }
+ }
+ spin_unlock(&dcache_lock);
+
+ return rc;
+}
+
+static int rebind_subsystems(struct rcfs_root *root, unsigned long final_bits)
+{
+ unsigned long added_bits, removed_bits;
+ int i, hierarchy;
+
+ removed_bits = root->subsys_bits & ~final_bits;
+ added_bits = final_bits & ~root->subsys_bits;
+ /* Check that any added subsystems are currently free */
+ for (i = 0; i < subsys_count; i++) {
+ unsigned long long bit = 1ull << i;
+ struct rc_subsys *ss = subsys[i];
+
+ if (!(bit & added_bits))
+ continue;
+ if (ss->hierarchy != 0) {
+ /* Subsystem isn't free */
+ return -EBUSY;
+ }
+ }
+
+ /* Currently we don't handle adding/removing subsystems when
+ * any subdirectories exist. This is theoretically supportable
+ * but involves complex erro r handling, so it's being left until
+ * later */
+ /*
+ if (!dir_empty(root->sb->s_root))
+ return -EBUSY;
+ */
+
+ hierarchy = rootnode - root;
+
+ /* Process each subsystem */
+ for (i = 0; i < subsys_count; i++) {
+ struct rc_subsys *ss = subsys[i];
+ unsigned long bit = 1UL << i;
+ if (bit & added_bits) {
+ /* We're binding this subsystem to this hierarchy */
+ list_add(&ss->sibling, &root->subsys_list);
+ rcu_assign_pointer(ss->hierarchy, hierarchy);
+ } else if (bit & removed_bits) {
+ /* We're removing this subsystem */
+ rcu_assign_pointer(subsys[i]->hierarchy, 0);
+ list_del(&ss->sibling);
+ }
+ }
+ root->subsys_bits = final_bits;
+ synchronize_rcu(); /* needed ? */
+
+ return 0;
+}
+
+/*
+ * Release the last use of a hierarchy. Will never be called when
+ * there are active subcontainers since each subcontainer bumps the
+ * value of sb->s_active.
+ */
+static void rcfs_put_super(struct super_block *sb) {
+
+ struct rcfs_root *root = sb->s_fs_info;
+ int ret;
+
+ mutex_lock(&manage_mutex);
+
+ BUG_ON(!root->subsys_bits);
+
+ /* Rebind all subsystems back to the default hierarchy */
+ ret = rebind_subsystems(root, 0);
+ root->sb = NULL;
+ sb->s_fs_info = NULL;
+
+ mutex_unlock(&manage_mutex);
+}
+
+static int rcfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
+{
+ struct rcfs_root *root = vfs->mnt_sb->s_fs_info;
+ struct rc_subsys *ss;
+
+ for_each_subsys(root, ss)
+ seq_printf(seq, ",%s", ss->name);
+
+ return 0;
+}
+
+/* Convert a hierarchy specifier into a bitmask. LL=manage_mutex */
+static int parse_rcfs_options(char *opts, unsigned long *bits)
+{
+ char *token, *o = opts ?: "all";
+
+ *bits = 0;
+
+ while ((token = strsep(&o, ",")) != NULL) {
+ if (!*token)
+ return -EINVAL;
+ if (!strcmp(token, "all")) {
+ *bits = (1 << subsys_count) - 1;
+ } else {
+ struct rc_subsys *ss;
+ int i;
+ for (i = 0; i < subsys_count; i++) {
+ ss = subsys[i];
+ if (!strcmp(token, ss->name)) {
+ *bits |= 1 << i;
+ break;
+ }
+ }
+ if (i == subsys_count)
+ return -ENOENT;
+ }
+ }
+
+ /* We can't have an empty hierarchy */
+ if (!*bits)
+ return -EINVAL;
+
+ return 0;
+}
+
+static struct backing_dev_info rcfs_backing_dev_info = {
+ .ra_pages = 0, /* No readahead */
+ .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
+};
+
+static struct inode *rcfs_new_inode(mode_t mode, struct super_block *sb)
+{
+ struct inode *inode = new_inode(sb);
+
+ if (inode) {
+ inode->i_mode = mode;
+ inode->i_uid = current->fsuid;
+ inode->i_gid = current->fsgid;
+ inode->i_blocks = 0;
+ inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+ inode->i_mapping->backing_dev_info = &rcfs_backing_dev_info;
+ }
+ return inode;
+}
+
+static struct super_operations rcfs_sb_ops = {
+ .statfs = simple_statfs,
+ .drop_inode = generic_delete_inode,
+ .put_super = rcfs_put_super,
+ .show_options = rcfs_show_options,
+ //.remount_fs = rcfs_remount,
+};
+
+static struct inode_operations rcfs_dir_inode_operations;
+static int rcfs_create_dir(struct nsproxy *ns, struct dentry *dentry,
+ int mode);
+static int rcfs_populate_dir(struct dentry *d);
+static void rcfs_d_remove_dir(struct dentry *dentry);
+
+static int rcfs_fill_super(struct super_block *sb, void *options,
+ int unused_silent)
+{
+ struct inode *inode;
+ struct dentry *root;
+ struct rcfs_root *hroot = options;
+
+ sb->s_blocksize = PAGE_CACHE_SIZE;
+ sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+ sb->s_magic = RCFS_SUPER_MAGIC;
+ sb->s_op = &rcfs_sb_ops;
+
+ inode = rcfs_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb);
+ if (!inode)
+ return -ENOMEM;
+
+ inode->i_op = &simple_dir_inode_operations;
+ inode->i_fop = &simple_dir_operations;
+ inode->i_op = &rcfs_dir_inode_operations;
+ /* directories start off with i_nlink == 2 (for "." entry) */
+ inc_nlink(inode);
+
+ root = d_alloc_root(inode);
+ if (!root) {
+ iput(inode);
+ return -ENOMEM;
+ }
+ sb->s_root = root;
+ get_task_namespaces(&init_task);
+ root->d_fsdata = init_task.nsproxy;
+ sb->s_fs_info = hroot;
+ hroot->sb = sb;
+
+ return 0;
+}
+
+/* Count the number of tasks in a container. Could be made more
+ * time-efficient but less space-efficient with more linked lists
+ * running through each container and the container_group structures
+ * that referenced it. */
+
+int rcfs_task_count(const struct nsproxy *ns)
+{
+ int count = 0;
+
+ count = atomic_read(&ns->count);
+
+ return count;
+}
+
+/*
+ * Stuff for reading the 'tasks' file.
+ *
+ * Reading this file can return large amounts of data if a container 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().
+ */
+
+/* containers_tasks_read array */
+
+struct ctr_struct {
+ char *buf;
+ int bufsz;
+};
+
+/*
+ * Load into 'pidarray' up to 'npids' of the tasks using container
+ * 'cont'. Return actual number of pids loaded. No need to
+ * task_lock(p) when reading out p->container, since we're in an RCU
+ * read section, so the container_group can't go away, and is
+ * immutable after creation.
+ */
+static int pid_array_load(pid_t *pidarray, int npids, struct nsproxy *ns)
+{
+ int n = 0;
+ struct task_struct *g, *p;
+
+ rcu_read_lock();
+ read_lock(&tasklist_lock);
+
+ do_each_thread(g, p) {
+ if (p->nsproxy == ns) {
+ pidarray[n++] = pid_nr(task_pid(p));
+ if (unlikely(n == npids))
+ goto array_full;
+ }
+ } while_each_thread(g, p);
+
+array_full:
+ read_unlock(&tasklist_lock);
+ 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;
+}
+
+static inline struct nsproxy *__d_ns(struct dentry *dentry)
+{
+ return dentry->d_fsdata;
+}
+
+
+static inline struct cftype *__d_cft(struct dentry *dentry)
+{
+ return dentry->d_fsdata;
+}
+
+/*
+ * Handle an open on 'tasks' file. Prepare a buffer listing the
+ * process id's of tasks currently attached to the container being opened.
+ *
+ * Does not require any specific container mutexes, and does not take any.
+ */
+static int rcfs_tasks_open(struct inode *unused, struct file *file)
+{
+ struct nsproxy *ns = __d_ns(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 container 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 container users didn't
+ * show up until sometime later on.
+ */
+ npids = rcfs_task_count(ns);
+ pidarray = kmalloc(npids * sizeof(pid_t), GFP_KERNEL);
+ if (!pidarray)
+ goto err1;
+
+ npids = pid_array_load(pidarray, npids, ns);
+ 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);
+ file->private_data = ctr;
+ return 0;
+
+err2:
+ kfree(pidarray);
+err1:
+ kfree(ctr);
+err0:
+ return -ENOMEM;
+}
+
+static ssize_t rcfs_tasks_read(struct nsproxy *ns,
+ struct cftype *cft,
+ struct file *file, char __user *buf,
+ size_t nbytes, loff_t *ppos)
+{
+ struct ctr_struct *ctr = file->private_data;
+
+ if (*ppos + nbytes > ctr->bufsz)
+ nbytes = ctr->bufsz - *ppos;
+ if (copy_to_user(buf, ctr->buf + *ppos, nbytes))
+ return -EFAULT;
+ *ppos += nbytes;
+ return nbytes;
+}
+
+static int rcfs_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;
+}
+/*
+ * Attach task 'tsk' to container 'cont'
+ *
+ * Call holding manage_mutex. May take callback_mutex and task_lock of
+ * the task 'pid' during call.
+ */
+
+static int attach_task(struct dentry *d, struct task_struct *tsk)
+{
+ int retval = 0;
+ struct rc_subsys *ss;
+ struct rcfs_root *root = d->d_sb->s_fs_info;
+ struct nsproxy *ns = __d_ns(d->d_parent);
+ struct nsproxy *oldns, *newns;
+ struct nsproxy dupns;
+
+ printk ("attaching task %d to %p \n", tsk->pid, ns);
+
+ /* Nothing to do if the task is already in that container */
+ if (tsk->nsproxy == ns)
+ return 0;
+
+ for_each_subsys(root, ss) {
+ if (ss->can_attach) {
+ retval = ss->can_attach(ss, ns, tsk);
+ if (retval) {
+ put_task_struct(tsk);
+ return retval;
+ }
+ }
+ }
+
+ /* Locate or allocate a new container_group for this task,
+ * based on its final set of containers */
+ get_task_namespaces(tsk);
+ oldns = tsk->nsproxy;
+ memcpy(&dupns, oldns, sizeof(dupns));
+ for_each_subsys(root, ss)
+ dupns.ctlr_data[ss->subsys_id] = ns->ctlr_data[ss->subsys_id];
+ newns = find_nsproxy(&dupns);
+ printk ("find_nsproxy returned %p \n", newns);
+ if (!newns) {
+ put_nsproxy(tsk->nsproxy);
+ put_task_struct(tsk);
+ return -ENOMEM;
+ }
+
+ task_lock(tsk); /* Needed ? */
+ rcu_assign_pointer(tsk->nsproxy, newns);
+ task_unlock(tsk);
+
+ for_each_subsys(root, ss) {
+ if (ss->attach)
+ ss->attach(ss, newns, oldns, tsk);
+ }
+
+ synchronize_rcu();
+ put_nsproxy(oldns);
+ return 0;
+}
+
+
+/*
+ * Attach task with pid 'pid' to container 'cont'. Call with
+ * manage_mutex, may take callback_mutex and task_lock of task
+ *
+ */
+
+static int attach_task_by_pid(struct dentry *d, char *pidbuf)
+{
+ pid_t pid;
+ struct task_struct *tsk;
+ int ret;
+
+ if (sscanf(pidbuf, "%d", &pid) != 1)
+ return -EIO;
+
+ if (pid) {
+ read_lock(&tasklist_lock);
+
+ tsk = find_task_by_pid(pid);
+ if (!tsk || tsk->flags & PF_EXITING) {
+ read_unlock(&tasklist_lock);
+ return -ESRCH;
+ }
+
+ get_task_struct(tsk);
+ read_unlock(&tasklist_lock);
+
+ 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(d, tsk);
+ put_task_struct(tsk);
+ return ret;
+}
+
+/* The various types of files and directories in a container file system */
+
+typedef enum {
+ FILE_ROOT,
+ FILE_DIR,
+ FILE_TASKLIST,
+} rcfs_filetype_t;
+
+static ssize_t rcfs_common_file_write(struct nsproxy *ns, struct cftype *cft,
+ struct file *file,
+ const char __user *userbuf,
+ size_t nbytes, loff_t *unused_ppos)
+{
+ rcfs_filetype_t type = cft->private;
+ char *buffer;
+ int retval = 0;
+
+ if (nbytes >= PATH_MAX)
+ return -E2BIG;
+
+ /* +1 for nul-terminator */
+ if ((buffer = kmalloc(nbytes + 1, GFP_KERNEL)) == 0)
+ return -ENOMEM;
+
+ if (copy_from_user(buffer, userbuf, nbytes)) {
+ retval = -EFAULT;
+ goto out1;
+ }
+ buffer[nbytes] = 0; /* nul-terminate */
+
+ mutex_lock(&manage_mutex);
+
+ ns = __d_ns(file->f_dentry);
+ if (!ns) {
+ retval = -ENODEV;
+ goto out2;
+ }
+
+ switch (type) {
+ case FILE_TASKLIST:
+ retval = attach_task_by_pid(file->f_dentry, buffer);
+ break;
+ default:
+ retval = -EINVAL;
+ goto out2;
+ }
+
+ if (retval == 0)
+ retval = nbytes;
+out2:
+ mutex_unlock(&manage_mutex);
+out1:
+ kfree(buffer);
+ return retval;
+}
+
+static struct cftype cft_tasks = {
+ .name = "tasks",
+ .open = rcfs_tasks_open,
+ .read = rcfs_tasks_read,
+ .write = rcfs_common_file_write,
+ .release = rcfs_tasks_release,
+ .private = FILE_TASKLIST,
+};
+
+static ssize_t rcfs_file_write(struct file *file, const char __user *buf,
+ size_t nbytes, loff_t *ppos)
+{
+ struct cftype *cft = __d_cft(file->f_dentry);
+ struct nsproxy *ns = __d_ns(file->f_dentry->d_parent);
+ if (!cft)
+ return -ENODEV;
+ if (!cft->write)
+ return -EINVAL;
+
+ return cft->write(ns, cft, file, buf, nbytes, ppos);
+}
+
+static ssize_t rcfs_file_read(struct file *file, char __user *buf,
+ size_t nbytes, loff_t *ppos)
+{
+ struct cftype *cft = __d_cft(file->f_dentry);
+ struct nsproxy *ns = __d_ns(file->f_dentry->d_parent);
+ if (!cft)
+ return -ENODEV;
+ if (!cft->read)
+ return -EINVAL;
+
+ return cft->read(ns, cft, file, buf, nbytes, ppos);
+}
+
+static int rcfs_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 rcfs_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;
+}
+
+/*
+ * rcfs_create - create a container
+ * parent: container that will be parent of the new container.
+ * name: name of the new container. Will be strcpy'ed.
+ * mode: mode to set on new inode
+ *
+ * Must be called with the mutex on the parent inode held
+ */
+
+static long rcfs_create(struct nsproxy *parent, struct dentry *dentry,
+ int mode)
+{
+ struct rcfs_root *root = dentry->d_sb->s_fs_info;
+ int err = 0;
+ struct rc_subsys *ss;
+ struct super_block *sb = dentry->d_sb;
+ struct nsproxy *ns;
+
+ ns = dup_namespaces(parent);
+ if (!ns)
+ return -ENOMEM;
+
+ printk ("rcfs_create: ns = %p \n", ns);
+
+ /* Grab a reference on the superblock so the hierarchy doesn't
+ * get deleted on unmount if there are child containers. This
+ * can be done outside manage_mutex, since the sb can't
+ * disappear while someone has an open control file on the
+ * fs */
+ atomic_inc(&sb->s_active);
+
+ mutex_lock(&manage_mutex);
+
+ for_each_subsys(root, ss) {
+ err = ss->create(ss, ns, parent);
+ if (err) {
+ printk ("%s create failed \n", ss->name);
+ goto err_destroy;
+ }
+ }
+
+ err = rcfs_create_dir(ns, dentry, mode);
+ if (err < 0)
+ goto err_destroy;
+
+ /* The container directory was pre-locked for us */
+ BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
+
+ err = rcfs_populate_dir(dentry);
+ /* If err < 0, we have a half-filled directory - oh well ;) */
+
+ mutex_unlock(&manage_mutex);
+ mutex_unlock(&dentry->d_inode->i_mutex);
+
+ return 0;
+
+err_destroy:
+
+ for_each_subsys(root, ss)
+ ss->destroy(ss, ns);
+
+ mutex_unlock(&manage_mutex);
+
+ /* Release the reference count that we took on the superblock */
+ deactivate_super(sb);
+
+ free_nsproxy(ns);
+ return err;
+}
+
+static int rcfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+ struct nsproxy *ns_parent = dentry->d_parent->d_fsdata;
+
+ printk ("rcfs_mkdir : parent_nsproxy = %p (%p) \n", ns_parent, dentry->d_fsdata);
+
+ /* the vfs holds inode->i_mutex already */
+ return rcfs_create(ns_parent, dentry, mode | S_IFDIR);
+}
+
+static int rcfs_rmdir(struct inode *unused_dir, struct dentry *dentry)
+{
+ struct nsproxy *ns = dentry->d_fsdata;
+ struct dentry *d;
+ struct rc_subsys *ss;
+ struct super_block *sb = dentry->d_sb;
+ struct rcfs_root *root = dentry->d_sb->s_fs_info;
+
+ /* the vfs holds both inode->i_mutex already */
+
+ mutex_lock(&manage_mutex);
+
+ if (atomic_read(&ns->count) > 1) {
+ mutex_unlock(&manage_mutex);
+ return -EBUSY;
+ }
+
+ if (!dir_empty(dentry)) {
+ mutex_unlock(&manage_mutex);
+ return -EBUSY;
+ }
+
+ for_each_subsys(root, ss)
+ ss->destroy(ss, ns);
+
+ spin_lock(&dentry->d_lock);
+ d = dget(dentry);
+ spin_unlock(&d->d_lock);
+
+ rcfs_d_remove_dir(d);
+ dput(d);
+
+ mutex_unlock(&manage_mutex);
+ /* Drop the active superblock reference that we took when we
+ * created the container */
+ deactivate_super(sb);
+ return 0;
+}
+
+static struct file_operations rcfs_file_operations = {
+ .read = rcfs_file_read,
+ .write = rcfs_file_write,
+ .llseek = generic_file_llseek,
+ .open = rcfs_file_open,
+ .release = rcfs_file_release,
+};
+
+static struct inode_operations rcfs_dir_inode_operations = {
+ .lookup = simple_lookup,
+ .mkdir = rcfs_mkdir,
+ .rmdir = rcfs_rmdir,
+ //.rename = rcfs_rename,
+};
+
+static int rcfs_create_file(struct dentry *dentry, int mode,
+ struct super_block *sb)
+{
+ struct inode *inode;
+
+ if (!dentry)
+ return -ENOENT;
+ if (dentry->d_inode)
+ return -EEXIST;
+
+ inode = rcfs_new_inode(mode, sb);
+ if (!inode)
+ return -ENOMEM;
+
+ if (S_ISDIR(mode)) {
+ inode->i_op = &rcfs_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 = &rcfs_file_operations;
+ }
+
+ d_instantiate(dentry, inode);
+ dget(dentry); /* Extra count - pin the dentry in core */
+ return 0;
+}
+
+/*
+ * rcfs_create_dir - create a directory for an object.
+ * cont: the container we create the directory for.
+ * It must have a valid ->parent field
+ * And we are going to fill its ->dentry field.
+ * name: The name to give to the container directory. Will be copied.
+ * mode: mode to set on new directory.
+ */
+
+static int rcfs_create_dir(struct nsproxy *ns, struct dentry *dentry,
+ int mode)
+{
+ struct dentry *parent;
+ int error = 0;
+
+ parent = dentry->d_parent;
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+ error = rcfs_create_file(dentry, S_IFDIR | mode, dentry->d_sb);
+ if (!error) {
+ dentry->d_fsdata = ns;
+ inc_nlink(parent->d_inode);
+ }
+ dput(dentry);
+
+ return error;
+}
+
+static void rcfs_diput(struct dentry *dentry, struct inode *inode)
+{
+ /* is dentry a directory ? if so, kfree() associated container */
+ if (S_ISDIR(inode->i_mode)) {
+ struct nsproxy *ns = dentry->d_fsdata;
+
+ free_nsproxy(ns);
+ dentry->d_fsdata = NULL;
+ }
+ iput(inode);
+}
+
+static struct dentry_operations rcfs_dops = {
+ .d_iput = rcfs_diput,
+};
+
+static struct dentry *rcfs_get_dentry(struct dentry *parent,
+ const char *name)
+{
+ struct dentry *d = lookup_one_len(name, parent, strlen(name));
+ if (!IS_ERR(d))
+ d->d_op = &rcfs_dops;
+ return d;
+}
+
+int rcfs_add_file(struct dentry *dir, const struct cftype *cft)
+{
+ struct dentry *dentry;
+ int error;
+
+ BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));
+ dentry = rcfs_get_dentry(dir, cft->name);
+ if (!IS_ERR(dentry)) {
+ error = rcfs_create_file(dentry, 0644 | S_IFREG, dir->d_sb);
+ if (!error)
+ dentry->d_fsdata = (void *)cft;
+ dput(dentry);
+ } else
+ error = PTR_ERR(dentry);
+ return error;
+}
+
+static void remove_dir(struct dentry *d)
+{
+ struct dentry *parent = dget(d->d_parent);
+
+ d_delete(d);
+ simple_rmdir(parent->d_inode, d);
+ dput(parent);
+}
+
+static void rcfs_clear_directory(struct dentry *dentry)
+{
+ struct list_head *node;
+
+ BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
+ spin_lock(&dcache_lock);
+ node = dentry->d_subdirs.next;
+ while (node != &dentry->d_subdirs) {
+ struct dentry *d = list_entry(node, struct dentry, d_u.d_child);
+ list_del_init(node);
+ if (d->d_inode) {
+ /* This should never be called on a container
+ * directory with child containers */
+ BUG_ON(d->d_inode->i_mode & S_IFDIR);
+ d = dget_locked(d);
+ spin_unlock(&dcache_lock);
+ d_delete(d);
+ simple_unlink(dentry->d_inode, d);
+ dput(d);
+ spin_lock(&dcache_lock);
+ }
+ node = dentry->d_subdirs.next;
+ }
+ spin_unlock(&dcache_lock);
+}
+
+/*
+ * NOTE : the dentry must have been dget()'ed
+ */
+static void rcfs_d_remove_dir(struct dentry *dentry)
+{
+ rcfs_clear_directory(dentry);
+
+ spin_lock(&dcache_lock);
+ list_del_init(&dentry->d_u.d_child);
+ spin_unlock(&dcache_lock);
+ remove_dir(dentry);
+}
+
+static int rcfs_populate_dir(struct dentry *d)
+{
+ int err;
+ struct rc_subsys *ss;
+ struct rcfs_root *root = d->d_sb->s_fs_info;
+
+ /* First clear out any existing files */
+ rcfs_clear_directory(d);
+
+ if ((err = rcfs_add_file(d, &cft_tasks)) < 0)
+ return err;
+
+ for_each_subsys(root, ss)
+ if (ss->populate && (err = ss->populate(ss, d)) < 0)
+ return err;
+
+ return 0;
+}
+
+static int rcfs_get_sb(struct file_system_type *fs_type,
+ int flags, const char *unused_dev_name,
+ void *data, struct vfsmount *mnt)
+{
+ int i;
+ unsigned long subsys_bits = 0;
+ int ret = 0;
+ struct rcfs_root *root = NULL;
+
+ mutex_lock(&manage_mutex);
+
+ /* First find the desired set of resource controllers */
+ ret = parse_rcfs_options(data, &subsys_bits);
+ if (ret)
+ goto out_unlock;
+
+ /* See if we already have a hierarchy containing this set */
+
+ for (i = 0; i < CONFIG_MAX_RC_HIERARCHIES; i++) {
+ root = &rootnode[i];
+ /* We match - use this hieracrchy */
+ if (root->subsys_bits == subsys_bits) break;
+ /* We clash - fail */
+ if (root->subsys_bits & subsys_bits) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+ }
+
+ if (i == CONFIG_MAX_RC_HIERARCHIES) {
+ /* No existing hierarchy matched this set - but we
+ * know that all the subsystems are free */
+ for (i = 0; i < CONFIG_MAX_RC_HIERARCHIES; i++) {
+ root = &rootnode[i];
+ if (!root->sb && !root->subsys_bits) break;
+ }
+ }
+
+ if (i == CONFIG_MAX_RC_HIERARCHIES) {
+ ret = -ENOSPC;
+ goto out_unlock;
+ }
+
+ if (!root->sb) {
+ BUG_ON(root->subsys_bits);
+ ret = get_sb_nodev(fs_type, flags, root,
+ rcfs_fill_super, mnt);
+ if (ret)
+ goto out_unlock;
+
+ ret = rebind_subsystems(root, subsys_bits);
+ BUG_ON(ret);
+
+ /* It's safe to nest i_mutex inside manage_mutex in
+ * this case, since no-one else can be accessing this
+ * directory yet */
+ mutex_lock(&root->sb->s_root->d_inode->i_mutex);
+ rcfs_populate_dir(root->sb->s_root);
+ mutex_unlock(&root->sb->s_root->d_inode->i_mutex);
+
+ } else {
+ /* Reuse the existing superblock */
+ ret = simple_set_mnt(mnt, root->sb);
+ if (!ret)
+ atomic_inc(&root->sb->s_active);
+ }
+
+out_unlock:
+ mutex_unlock(&manage_mutex);
+ return ret;
+}
+
+static struct file_system_type rcfs_type = {
+ .name = "rcfs",
+ .get_sb = rcfs_get_sb,
+ .kill_sb = kill_litter_super,
+};
+
+int __init rcfs_init(void)
+{
+ int i, err;
+
+ for (i=0; i < CONFIG_MAX_RC_HIERARCHIES; ++i)
+ INIT_LIST_HEAD(&rootnode[i].subsys_list);
+
+ err = register_filesystem(&rcfs_type);
+
+ return err;
+}
+
+int rc_register_subsys(struct rc_subsys *new_subsys)
+{
+ int retval = 0;
+ int i;
+ int ss_id;
+
+ BUG_ON(new_subsys->hierarchy);
+ BUG_ON(new_subsys->active);
+
+ mutex_lock(&manage_mutex);
+
+ if (subsys_count == CONFIG_MAX_RC_SUBSYS) {
+ retval = -ENOSPC;
+ goto out;
+ }
+
+ /* Sanity check the subsystem */
+ if (!new_subsys->name ||
+ (strlen(new_subsys->name) > MAX_CONTAINER_TYPE_NAMELEN) ||
+ !new_subsys->create || !new_subsys->destroy) {
+ retval = -EINVAL;
+ goto out;
+ }
+
+ /* Check this isn't a duplicate */
+ for (i = 0; i < subsys_count; i++) {
+ if (!strcmp(subsys[i]->name, new_subsys->name)) {
+ retval = -EEXIST;
+ goto out;
+ }
+ }
+
+ /* Create the top container state for this subsystem */
+ ss_id = new_subsys->subsys_id = subsys_count;
+ retval = new_subsys->create(new_subsys, &init_nsproxy, NULL);
+ if (retval) {
+ new_subsys->subsys_id = -1;
+ goto out;
+ }
+
+ subsys[subsys_count++] = new_subsys;
+ new_subsys->active = 1;
+out:
+ mutex_unlock(&manage_mutex);
+ return retval;
+}
+
_

--
Regards,
vatsa