[deliverable/linux.git] / fs / nsfs.c

#include <linux/mount.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/proc_ns.h>
#include <linux/magic.h>
#include <linux/ktime.h>
#include <linux/seq_file.h>

static struct vfsmount *nsfs_mnt;

static const struct file_operations ns_file_operations = {
	.llseek		= no_llseek,
};

static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
{
	struct inode *inode = d_inode(dentry);
	const struct proc_ns_operations *ns_ops = dentry->d_fsdata;

	return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]",
		ns_ops->name, inode->i_ino);
}

static void ns_prune_dentry(struct dentry *dentry)
{
	struct inode *inode = d_inode(dentry);
	if (inode) {
		struct ns_common *ns = inode->i_private;
		atomic_long_set(&ns->stashed, 0);
	}
}

const struct dentry_operations ns_dentry_operations =
{
	.d_prune	= ns_prune_dentry,
	.d_delete	= always_delete_dentry,
	.d_dname	= ns_dname,
};

static void nsfs_evict(struct inode *inode)
{
	struct ns_common *ns = inode->i_private;
	clear_inode(inode);
	ns->ops->put(ns);
}

void *ns_get_path(struct path *path, struct task_struct *task,
			const struct proc_ns_operations *ns_ops)
{
	struct vfsmount *mnt = mntget(nsfs_mnt);
	struct qstr qname = { .name = "", };
	struct dentry *dentry;
	struct inode *inode;
	struct ns_common *ns;
	unsigned long d;

again:
	ns = ns_ops->get(task);
	if (!ns) {
		mntput(mnt);
		return ERR_PTR(-ENOENT);
	}
	rcu_read_lock();
	d = atomic_long_read(&ns->stashed);
	if (!d)
		goto slow;
	dentry = (struct dentry *)d;
	if (!lockref_get_not_dead(&dentry->d_lockref))
		goto slow;
	rcu_read_unlock();
	ns_ops->put(ns);
got_it:
	path->mnt = mnt;
	path->dentry = dentry;
	return NULL;
slow:
	rcu_read_unlock();
	inode = new_inode_pseudo(mnt->mnt_sb);
	if (!inode) {
		ns_ops->put(ns);
		mntput(mnt);
		return ERR_PTR(-ENOMEM);
	}
	inode->i_ino = ns->inum;
	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	inode->i_flags |= S_IMMUTABLE;
	inode->i_mode = S_IFREG | S_IRUGO;
	inode->i_fop = &ns_file_operations;
	inode->i_private = ns;

	dentry = d_alloc_pseudo(mnt->mnt_sb, &qname);
	if (!dentry) {
		iput(inode);
		mntput(mnt);
		return ERR_PTR(-ENOMEM);
	}
	d_instantiate(dentry, inode);
	dentry->d_fsdata = (void *)ns_ops;
	d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry);
	if (d) {
		d_delete(dentry);	/* make sure ->d_prune() does nothing */
		dput(dentry);
		cpu_relax();
		goto again;
	}
	goto got_it;
}

int ns_get_name(char *buf, size_t size, struct task_struct *task,
			const struct proc_ns_operations *ns_ops)
{
	struct ns_common *ns;
	int res = -ENOENT;
	ns = ns_ops->get(task);
	if (ns) {
		res = snprintf(buf, size, "%s:[%u]", ns_ops->name, ns->inum);
		ns_ops->put(ns);
	}
	return res;
}

struct file *proc_ns_fget(int fd)
{
	struct file *file;

	file = fget(fd);
	if (!file)
		return ERR_PTR(-EBADF);

	if (file->f_op != &ns_file_operations)
		goto out_invalid;

	return file;

out_invalid:
	fput(file);
	return ERR_PTR(-EINVAL);
}

static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
{
	struct inode *inode = d_inode(dentry);
	const struct proc_ns_operations *ns_ops = dentry->d_fsdata;

	seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);
	return 0;
}

static const struct super_operations nsfs_ops = {
	.statfs = simple_statfs,
	.evict_inode = nsfs_evict,
	.show_path = nsfs_show_path,
};
static struct dentry *nsfs_mount(struct file_system_type *fs_type,
			int flags, const char *dev_name, void *data)
{
	return mount_pseudo(fs_type, "nsfs:", &nsfs_ops,
			&ns_dentry_operations, NSFS_MAGIC);
}
static struct file_system_type nsfs = {
	.name = "nsfs",
	.mount = nsfs_mount,
	.kill_sb = kill_anon_super,
};

void __init nsfs_init(void)
{
	nsfs_mnt = kern_mount(&nsfs);
	if (IS_ERR(nsfs_mnt))
		panic("can't set nsfs up\n");
	nsfs_mnt->mnt_sb->s_flags &= ~MS_NOUSER;
}
Commit	Line	Data
e149ed2b AV	1	#include <linux/mount.h>
	2	#include <linux/file.h>
	3	#include <linux/fs.h>
	4	#include <linux/proc_ns.h>
	5	#include <linux/magic.h>
	6	#include <linux/ktime.h>
75509fd8	7	#include <linux/seq_file.h>
e149ed2b AV	8
	9	static struct vfsmount *nsfs_mnt;
	10
	11	static const struct file_operations ns_file_operations = {
	12	.llseek = no_llseek,
	13	};
	14
	15	static char ns_dname(struct dentry dentry, char *buffer, int buflen)
	16	{
75c3cfa8	17	struct inode *inode = d_inode(dentry);
e149ed2b AV	18	const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
	19
	20	return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]",
	21	ns_ops->name, inode->i_ino);
	22	}
	23
	24	static void ns_prune_dentry(struct dentry *dentry)
	25	{
75c3cfa8	26	struct inode *inode = d_inode(dentry);
e149ed2b AV	27	if (inode) {
	28	struct ns_common *ns = inode->i_private;
	29	atomic_long_set(&ns->stashed, 0);
	30	}
	31	}
	32
	33	const struct dentry_operations ns_dentry_operations =
	34	{
	35	.d_prune = ns_prune_dentry,
	36	.d_delete = always_delete_dentry,
	37	.d_dname = ns_dname,
	38	};
	39
	40	static void nsfs_evict(struct inode *inode)
	41	{
	42	struct ns_common *ns = inode->i_private;
	43	clear_inode(inode);
	44	ns->ops->put(ns);
	45	}
	46
	47	void ns_get_path(struct path path, struct task_struct *task,
	48	const struct proc_ns_operations *ns_ops)
	49	{
	50	struct vfsmount *mnt = mntget(nsfs_mnt);
	51	struct qstr qname = { .name = "", };
	52	struct dentry *dentry;
	53	struct inode *inode;
	54	struct ns_common *ns;
	55	unsigned long d;
	56
	57	again:
	58	ns = ns_ops->get(task);
	59	if (!ns) {
	60	mntput(mnt);
	61	return ERR_PTR(-ENOENT);
	62	}
	63	rcu_read_lock();
	64	d = atomic_long_read(&ns->stashed);
	65	if (!d)
	66	goto slow;
	67	dentry = (struct dentry *)d;
	68	if (!lockref_get_not_dead(&dentry->d_lockref))
	69	goto slow;
	70	rcu_read_unlock();
	71	ns_ops->put(ns);
	72	got_it:
	73	path->mnt = mnt;
	74	path->dentry = dentry;
	75	return NULL;
	76	slow:
	77	rcu_read_unlock();
	78	inode = new_inode_pseudo(mnt->mnt_sb);
	79	if (!inode) {
	80	ns_ops->put(ns);
	81	mntput(mnt);
	82	return ERR_PTR(-ENOMEM);
	83	}
	84	inode->i_ino = ns->inum;
	85	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	86	inode->i_flags \|= S_IMMUTABLE;
	87	inode->i_mode = S_IFREG \| S_IRUGO;
	88	inode->i_fop = &ns_file_operations;
	89	inode->i_private = ns;
	90
91	dentry = d_alloc_pseudo(mnt->mnt_sb, &qname);
92	if (!dentry) {
93	iput(inode);
94	mntput(mnt);
95	return ERR_PTR(-ENOMEM);
96	}
97	d_instantiate(dentry, inode);
98	dentry->d_fsdata = (void *)ns_ops;
99	d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry);
100	if (d) {
101	d_delete(dentry); /* make sure ->d_prune() does nothing */
102	dput(dentry);
103	cpu_relax();
104	goto again;
105	}
106	goto got_it;
107	}
108
109	int ns_get_name(char buf, size_t size, struct task_struct task,
110	const struct proc_ns_operations *ns_ops)
111	{
112	struct ns_common *ns;
113	int res = -ENOENT;
114	ns = ns_ops->get(task);
115	if (ns) {
116	res = snprintf(buf, size, "%s:[%u]", ns_ops->name, ns->inum);
117	ns_ops->put(ns);
118	}
119	return res;
120	}
121
122	struct file *proc_ns_fget(int fd)
123	{
124	struct file *file;
125
126	file = fget(fd);
127	if (!file)
128	return ERR_PTR(-EBADF);
129
130	if (file->f_op != &ns_file_operations)
131	goto out_invalid;
132
133	return file;
134
135	out_invalid:
136	fput(file);
137	return ERR_PTR(-EINVAL);
138	}
139
75509fd8 EB	140	static int nsfs_show_path(struct seq_file seq, struct dentry dentry)
	141	{
	142	struct inode *inode = d_inode(dentry);
	143	const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
	144
6798a8ca JP	145	seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);
6798a8ca JP	146	return 0;
75509fd8 EB	147	}
75509fd8 EB	148
e149ed2b AV	149	static const struct super_operations nsfs_ops = {
	150	.statfs = simple_statfs,
	151	.evict_inode = nsfs_evict,
75509fd8	152	.show_path = nsfs_show_path,
e149ed2b AV	153	};
	154	static struct dentry nsfs_mount(struct file_system_type fs_type,
	155	int flags, const char dev_name, void data)
	156	{
	157	return mount_pseudo(fs_type, "nsfs:", &nsfs_ops,
	158	&ns_dentry_operations, NSFS_MAGIC);
	159	}
	160	static struct file_system_type nsfs = {
	161	.name = "nsfs",
	162	.mount = nsfs_mount,
	163	.kill_sb = kill_anon_super,
	164	};
	165
	166	void __init nsfs_init(void)
	167	{
	168	nsfs_mnt = kern_mount(&nsfs);
	169	if (IS_ERR(nsfs_mnt))
	170	panic("can't set nsfs up\n");
	171	nsfs_mnt->mnt_sb->s_flags &= ~MS_NOUSER;
	172	}