[mirror_ubuntu-zesty-kernel.git] / fs / proc / inode.c

/*
 *  linux/fs/proc/inode.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/time.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/completion.h>
#include <linux/poll.h>
#include <linux/file.h>
#include <linux/limits.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/sysctl.h>
#include <linux/slab.h>

#include <asm/system.h>
#include <asm/uaccess.h>

#include "internal.h"

static void proc_evict_inode(struct inode *inode)
{
	struct proc_dir_entry *de;

	truncate_inode_pages(&inode->i_data, 0);
	end_writeback(inode);

	/* Stop tracking associated processes */
	put_pid(PROC_I(inode)->pid);

	/* Let go of any associated proc directory entry */
	de = PROC_I(inode)->pde;
	if (de)
		pde_put(de);
	if (PROC_I(inode)->sysctl)
		sysctl_head_put(PROC_I(inode)->sysctl);
}

struct vfsmount *proc_mnt;

static struct kmem_cache * proc_inode_cachep;

static struct inode *proc_alloc_inode(struct super_block *sb)
{
	struct proc_inode *ei;
	struct inode *inode;

	ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
	if (!ei)
		return NULL;
	ei->pid = NULL;
	ei->fd = 0;
	ei->op.proc_get_link = NULL;
	ei->pde = NULL;
	ei->sysctl = NULL;
	ei->sysctl_entry = NULL;
	inode = &ei->vfs_inode;
	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	return inode;
}

static void proc_i_callback(struct rcu_head *head)
{
	struct inode *inode = container_of(head, struct inode, i_rcu);
	INIT_LIST_HEAD(&inode->i_dentry);
	kmem_cache_free(proc_inode_cachep, PROC_I(inode));
}

static void proc_destroy_inode(struct inode *inode)
{
	call_rcu(&inode->i_rcu, proc_i_callback);
}

static void init_once(void *foo)
{
	struct proc_inode *ei = (struct proc_inode *) foo;

	inode_init_once(&ei->vfs_inode);
}

void __init proc_init_inodecache(void)
{
	proc_inode_cachep = kmem_cache_create("proc_inode_cache",
					     sizeof(struct proc_inode),
					     0, (SLAB_RECLAIM_ACCOUNT|
						SLAB_MEM_SPREAD|SLAB_PANIC),
					     init_once);
}

static const struct super_operations proc_sops = {
	.alloc_inode	= proc_alloc_inode,
	.destroy_inode	= proc_destroy_inode,
	.drop_inode	= generic_delete_inode,
	.evict_inode	= proc_evict_inode,
	.statfs		= simple_statfs,
};

static void __pde_users_dec(struct proc_dir_entry *pde)
{
	pde->pde_users--;
	if (pde->pde_unload_completion && pde->pde_users == 0)
		complete(pde->pde_unload_completion);
}

void pde_users_dec(struct proc_dir_entry *pde)
{
	spin_lock(&pde->pde_unload_lock);
	__pde_users_dec(pde);
	spin_unlock(&pde->pde_unload_lock);
}

static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
{
	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	loff_t rv = -EINVAL;
	loff_t (*llseek)(struct file *, loff_t, int);

	spin_lock(&pde->pde_unload_lock);
	/*
	 * remove_proc_entry() is going to delete PDE (as part of module
	 * cleanup sequence). No new callers into module allowed.
	 */
	if (!pde->proc_fops) {
		spin_unlock(&pde->pde_unload_lock);
		return rv;
	}
	/*
	 * Bump refcount so that remove_proc_entry will wail for ->llseek to
	 * complete.
	 */
	pde->pde_users++;
	/*
	 * Save function pointer under lock, to protect against ->proc_fops
	 * NULL'ifying right after ->pde_unload_lock is dropped.
	 */
	llseek = pde->proc_fops->llseek;
	spin_unlock(&pde->pde_unload_lock);

	if (!llseek)
		llseek = default_llseek;
	rv = llseek(file, offset, whence);

	pde_users_dec(pde);
	return rv;
}

static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	ssize_t rv = -EIO;
	ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);

	spin_lock(&pde->pde_unload_lock);
	if (!pde->proc_fops) {
		spin_unlock(&pde->pde_unload_lock);
		return rv;
	}
	pde->pde_users++;
	read = pde->proc_fops->read;
	spin_unlock(&pde->pde_unload_lock);

	if (read)
		rv = read(file, buf, count, ppos);

	pde_users_dec(pde);
	return rv;
}

static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	ssize_t rv = -EIO;
	ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);

	spin_lock(&pde->pde_unload_lock);
	if (!pde->proc_fops) {
		spin_unlock(&pde->pde_unload_lock);
		return rv;
	}
	pde->pde_users++;
	write = pde->proc_fops->write;
	spin_unlock(&pde->pde_unload_lock);

	if (write)
		rv = write(file, buf, count, ppos);

	pde_users_dec(pde);
	return rv;
}

static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts)
{
	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	unsigned int rv = DEFAULT_POLLMASK;
	unsigned int (*poll)(struct file *, struct poll_table_struct *);

	spin_lock(&pde->pde_unload_lock);
	if (!pde->proc_fops) {
		spin_unlock(&pde->pde_unload_lock);
		return rv;
	}
	pde->pde_users++;
	poll = pde->proc_fops->poll;
	spin_unlock(&pde->pde_unload_lock);

	if (poll)
		rv = poll(file, pts);

	pde_users_dec(pde);
	return rv;
}

static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	long rv = -ENOTTY;
	long (*ioctl)(struct file *, unsigned int, unsigned long);

	spin_lock(&pde->pde_unload_lock);
	if (!pde->proc_fops) {
		spin_unlock(&pde->pde_unload_lock);
		return rv;
	}
	pde->pde_users++;
	ioctl = pde->proc_fops->unlocked_ioctl;
	spin_unlock(&pde->pde_unload_lock);

	if (ioctl)
		rv = ioctl(file, cmd, arg);

	pde_users_dec(pde);
	return rv;
}

#ifdef CONFIG_COMPAT
static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	long rv = -ENOTTY;
	long (*compat_ioctl)(struct file *, unsigned int, unsigned long);

	spin_lock(&pde->pde_unload_lock);
	if (!pde->proc_fops) {
		spin_unlock(&pde->pde_unload_lock);
		return rv;
	}
	pde->pde_users++;
	compat_ioctl = pde->proc_fops->compat_ioctl;
	spin_unlock(&pde->pde_unload_lock);

	if (compat_ioctl)
		rv = compat_ioctl(file, cmd, arg);

	pde_users_dec(pde);
	return rv;
}
#endif

static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
{
	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	int rv = -EIO;
	int (*mmap)(struct file *, struct vm_area_struct *);

	spin_lock(&pde->pde_unload_lock);
	if (!pde->proc_fops) {
		spin_unlock(&pde->pde_unload_lock);
		return rv;
	}
	pde->pde_users++;
	mmap = pde->proc_fops->mmap;
	spin_unlock(&pde->pde_unload_lock);

	if (mmap)
		rv = mmap(file, vma);

	pde_users_dec(pde);
	return rv;
}

static int proc_reg_open(struct inode *inode, struct file *file)
{
	struct proc_dir_entry *pde = PDE(inode);
	int rv = 0;
	int (*open)(struct inode *, struct file *);
	int (*release)(struct inode *, struct file *);
	struct pde_opener *pdeo;

	/*
	 * What for, you ask? Well, we can have open, rmmod, remove_proc_entry
	 * sequence. ->release won't be called because ->proc_fops will be
	 * cleared. Depending on complexity of ->release, consequences vary.
	 *
	 * We can't wait for mercy when close will be done for real, it's
	 * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release
	 * by hand in remove_proc_entry(). For this, save opener's credentials
	 * for later.
	 */
	pdeo = kmalloc(sizeof(struct pde_opener), GFP_KERNEL);
	if (!pdeo)
		return -ENOMEM;

	spin_lock(&pde->pde_unload_lock);
	if (!pde->proc_fops) {
		spin_unlock(&pde->pde_unload_lock);
		kfree(pdeo);
		return -EINVAL;
	}
	pde->pde_users++;
	open = pde->proc_fops->open;
	release = pde->proc_fops->release;
	spin_unlock(&pde->pde_unload_lock);

	if (open)
		rv = open(inode, file);

	spin_lock(&pde->pde_unload_lock);
	if (rv == 0 && release) {
		/* To know what to release. */
		pdeo->inode = inode;
		pdeo->file = file;
		/* Strictly for "too late" ->release in proc_reg_release(). */
		pdeo->release = release;
		list_add(&pdeo->lh, &pde->pde_openers);
	} else
		kfree(pdeo);
	__pde_users_dec(pde);
	spin_unlock(&pde->pde_unload_lock);
	return rv;
}

static struct pde_opener *find_pde_opener(struct proc_dir_entry *pde,
					struct inode *inode, struct file *file)
{
	struct pde_opener *pdeo;

	list_for_each_entry(pdeo, &pde->pde_openers, lh) {
		if (pdeo->inode == inode && pdeo->file == file)
			return pdeo;
	}
	return NULL;
}

static int proc_reg_release(struct inode *inode, struct file *file)
{
	struct proc_dir_entry *pde = PDE(inode);
	int rv = 0;
	int (*release)(struct inode *, struct file *);
	struct pde_opener *pdeo;

	spin_lock(&pde->pde_unload_lock);
	pdeo = find_pde_opener(pde, inode, file);
	if (!pde->proc_fops) {
		/*
		 * Can't simply exit, __fput() will think that everything is OK,
		 * and move on to freeing struct file. remove_proc_entry() will
		 * find slacker in opener's list and will try to do non-trivial
		 * things with struct file. Therefore, remove opener from list.
		 *
		 * But if opener is removed from list, who will ->release it?
		 */
		if (pdeo) {
			list_del(&pdeo->lh);
			spin_unlock(&pde->pde_unload_lock);
			rv = pdeo->release(inode, file);
			kfree(pdeo);
		} else
			spin_unlock(&pde->pde_unload_lock);
		return rv;
	}
	pde->pde_users++;
	release = pde->proc_fops->release;
	if (pdeo) {
		list_del(&pdeo->lh);
		kfree(pdeo);
	}
	spin_unlock(&pde->pde_unload_lock);

	if (release)
		rv = release(inode, file);

	pde_users_dec(pde);
	return rv;
}

static const struct file_operations proc_reg_file_ops = {
	.llseek		= proc_reg_llseek,
	.read		= proc_reg_read,
	.write		= proc_reg_write,
	.poll		= proc_reg_poll,
	.unlocked_ioctl	= proc_reg_unlocked_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= proc_reg_compat_ioctl,
#endif
	.mmap		= proc_reg_mmap,
	.open		= proc_reg_open,
	.release	= proc_reg_release,
};

#ifdef CONFIG_COMPAT
static const struct file_operations proc_reg_file_ops_no_compat = {
	.llseek		= proc_reg_llseek,
	.read		= proc_reg_read,
	.write		= proc_reg_write,
	.poll		= proc_reg_poll,
	.unlocked_ioctl	= proc_reg_unlocked_ioctl,
	.mmap		= proc_reg_mmap,
	.open		= proc_reg_open,
	.release	= proc_reg_release,
};
#endif

struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
{
	struct inode * inode;

	inode = iget_locked(sb, de->low_ino);
	if (!inode)
		return NULL;
	if (inode->i_state & I_NEW) {
		inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
		PROC_I(inode)->fd = 0;
		PROC_I(inode)->pde = de;

		if (de->mode) {
			inode->i_mode = de->mode;
			inode->i_uid = de->uid;
			inode->i_gid = de->gid;
		}
		if (de->size)
			inode->i_size = de->size;
		if (de->nlink)
			inode->i_nlink = de->nlink;
		if (de->proc_iops)
			inode->i_op = de->proc_iops;
		if (de->proc_fops) {
			if (S_ISREG(inode->i_mode)) {
#ifdef CONFIG_COMPAT
				if (!de->proc_fops->compat_ioctl)
					inode->i_fop =
						&proc_reg_file_ops_no_compat;
				else
#endif
					inode->i_fop = &proc_reg_file_ops;
			} else {
				inode->i_fop = de->proc_fops;
			}
		}
		unlock_new_inode(inode);
	} else
	       pde_put(de);
	return inode;
}			

int proc_fill_super(struct super_block *s)
{
	struct inode * root_inode;

	s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
	s->s_blocksize = 1024;
	s->s_blocksize_bits = 10;
	s->s_magic = PROC_SUPER_MAGIC;
	s->s_op = &proc_sops;
	s->s_time_gran = 1;
	
	pde_get(&proc_root);
	root_inode = proc_get_inode(s, &proc_root);
	if (!root_inode)
		goto out_no_root;
	root_inode->i_uid = 0;
	root_inode->i_gid = 0;
	s->s_root = d_alloc_root(root_inode);
	if (!s->s_root)
		goto out_no_root;
	return 0;

out_no_root:
	printk("proc_read_super: get root inode failed\n");
	iput(root_inode);
	pde_put(&proc_root);
	return -ENOMEM;
}
Commit	Line	Data
	1	/*
	2	* linux/fs/proc/inode.c
	3	*
	4	* Copyright (C) 1991, 1992 Linus Torvalds
	5	*/
	6
	7	#include <linux/time.h>
	8	#include <linux/proc_fs.h>
	9	#include <linux/kernel.h>
	10	#include <linux/mm.h>
	11	#include <linux/string.h>
	12	#include <linux/stat.h>
	13	#include <linux/completion.h>
	14	#include <linux/poll.h>
	15	#include <linux/file.h>
	16	#include <linux/limits.h>
	17	#include <linux/init.h>
	18	#include <linux/module.h>
	19	#include <linux/sysctl.h>
	20	#include <linux/slab.h>
	21
	22	#include <asm/system.h>
	23	#include <asm/uaccess.h>
	24
	25	#include "internal.h"
	26
	27	static void proc_evict_inode(struct inode *inode)
	28	{
	29	struct proc_dir_entry *de;
	30
	31	truncate_inode_pages(&inode->i_data, 0);
	32	end_writeback(inode);
	33
	34	/* Stop tracking associated processes */
	35	put_pid(PROC_I(inode)->pid);
	36
	37	/* Let go of any associated proc directory entry */
	38	de = PROC_I(inode)->pde;
	39	if (de)
	40	pde_put(de);
	41	if (PROC_I(inode)->sysctl)
	42	sysctl_head_put(PROC_I(inode)->sysctl);
	43	}
	44
	45	struct vfsmount *proc_mnt;
	46
	47	static struct kmem_cache * proc_inode_cachep;
	48
	49	static struct inode proc_alloc_inode(struct super_block sb)
	50	{
	51	struct proc_inode *ei;
	52	struct inode *inode;
	53
	54	ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
	55	if (!ei)
	56	return NULL;
	57	ei->pid = NULL;
	58	ei->fd = 0;
	59	ei->op.proc_get_link = NULL;
	60	ei->pde = NULL;
	61	ei->sysctl = NULL;
	62	ei->sysctl_entry = NULL;
	63	inode = &ei->vfs_inode;
	64	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	65	return inode;
	66	}
	67
	68	static void proc_i_callback(struct rcu_head *head)
	69	{
	70	struct inode *inode = container_of(head, struct inode, i_rcu);
	71	INIT_LIST_HEAD(&inode->i_dentry);
	72	kmem_cache_free(proc_inode_cachep, PROC_I(inode));
	73	}
	74
	75	static void proc_destroy_inode(struct inode *inode)
	76	{
	77	call_rcu(&inode->i_rcu, proc_i_callback);
	78	}
	79
	80	static void init_once(void *foo)
	81	{
	82	struct proc_inode ei = (struct proc_inode ) foo;
	83
	84	inode_init_once(&ei->vfs_inode);
	85	}
	86
	87	void __init proc_init_inodecache(void)
	88	{
	89	proc_inode_cachep = kmem_cache_create("proc_inode_cache",
	90	sizeof(struct proc_inode),
	91	0, (SLAB_RECLAIM_ACCOUNT\|
	92	SLAB_MEM_SPREAD\|SLAB_PANIC),
	93	init_once);
	94	}
	95
	96	static const struct super_operations proc_sops = {
	97	.alloc_inode = proc_alloc_inode,
	98	.destroy_inode = proc_destroy_inode,
	99	.drop_inode = generic_delete_inode,
	100	.evict_inode = proc_evict_inode,
	101	.statfs = simple_statfs,
	102	};
	103
	104	static void __pde_users_dec(struct proc_dir_entry *pde)
	105	{
	106	pde->pde_users--;
	107	if (pde->pde_unload_completion && pde->pde_users == 0)
	108	complete(pde->pde_unload_completion);
	109	}
	110
	111	void pde_users_dec(struct proc_dir_entry *pde)
	112	{
	113	spin_lock(&pde->pde_unload_lock);
	114	__pde_users_dec(pde);
	115	spin_unlock(&pde->pde_unload_lock);
	116	}
	117
	118	static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
	119	{
	120	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	121	loff_t rv = -EINVAL;
	122	loff_t (llseek)(struct file , loff_t, int);
	123
	124	spin_lock(&pde->pde_unload_lock);
	125	/*
	126	* remove_proc_entry() is going to delete PDE (as part of module
	127	* cleanup sequence). No new callers into module allowed.
	128	*/
	129	if (!pde->proc_fops) {
	130	spin_unlock(&pde->pde_unload_lock);
	131	return rv;
	132	}
	133	/*
	134	* Bump refcount so that remove_proc_entry will wail for ->llseek to
	135	* complete.
	136	*/
	137	pde->pde_users++;
	138	/*
	139	* Save function pointer under lock, to protect against ->proc_fops
	140	* NULL'ifying right after ->pde_unload_lock is dropped.
	141	*/
	142	llseek = pde->proc_fops->llseek;
	143	spin_unlock(&pde->pde_unload_lock);
	144
	145	if (!llseek)
	146	llseek = default_llseek;
	147	rv = llseek(file, offset, whence);
	148
	149	pde_users_dec(pde);
	150	return rv;
	151	}
	152
	153	static ssize_t proc_reg_read(struct file file, char __user buf, size_t count, loff_t *ppos)
	154	{
	155	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	156	ssize_t rv = -EIO;
	157	ssize_t (read)(struct file , char __user , size_t, loff_t );
	158
	159	spin_lock(&pde->pde_unload_lock);
	160	if (!pde->proc_fops) {
	161	spin_unlock(&pde->pde_unload_lock);
	162	return rv;
	163	}
	164	pde->pde_users++;
	165	read = pde->proc_fops->read;
	166	spin_unlock(&pde->pde_unload_lock);
	167
	168	if (read)
	169	rv = read(file, buf, count, ppos);
	170
	171	pde_users_dec(pde);
	172	return rv;
	173	}
	174
	175	static ssize_t proc_reg_write(struct file file, const char __user buf, size_t count, loff_t *ppos)
	176	{
	177	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	178	ssize_t rv = -EIO;
	179	ssize_t (write)(struct file , const char __user , size_t, loff_t );
	180
	181	spin_lock(&pde->pde_unload_lock);
	182	if (!pde->proc_fops) {
	183	spin_unlock(&pde->pde_unload_lock);
	184	return rv;
	185	}
	186	pde->pde_users++;
	187	write = pde->proc_fops->write;
	188	spin_unlock(&pde->pde_unload_lock);
	189
	190	if (write)
	191	rv = write(file, buf, count, ppos);
	192
	193	pde_users_dec(pde);
	194	return rv;
	195	}
	196
	197	static unsigned int proc_reg_poll(struct file file, struct poll_table_struct pts)
	198	{
	199	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	200	unsigned int rv = DEFAULT_POLLMASK;
	201	unsigned int (poll)(struct file , struct poll_table_struct *);
	202
	203	spin_lock(&pde->pde_unload_lock);
	204	if (!pde->proc_fops) {
	205	spin_unlock(&pde->pde_unload_lock);
	206	return rv;
	207	}
	208	pde->pde_users++;
	209	poll = pde->proc_fops->poll;
	210	spin_unlock(&pde->pde_unload_lock);
	211
	212	if (poll)
	213	rv = poll(file, pts);
	214
	215	pde_users_dec(pde);
	216	return rv;
	217	}
	218
	219	static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
	220	{
	221	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	222	long rv = -ENOTTY;
	223	long (ioctl)(struct file , unsigned int, unsigned long);
	224
	225	spin_lock(&pde->pde_unload_lock);
	226	if (!pde->proc_fops) {
	227	spin_unlock(&pde->pde_unload_lock);
	228	return rv;
	229	}
	230	pde->pde_users++;
	231	ioctl = pde->proc_fops->unlocked_ioctl;
	232	spin_unlock(&pde->pde_unload_lock);
	233
	234	if (ioctl)
	235	rv = ioctl(file, cmd, arg);
	236
	237	pde_users_dec(pde);
	238	return rv;
	239	}
	240
	241	#ifdef CONFIG_COMPAT
	242	static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
	243	{
	244	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	245	long rv = -ENOTTY;
	246	long (compat_ioctl)(struct file , unsigned int, unsigned long);
	247
	248	spin_lock(&pde->pde_unload_lock);
	249	if (!pde->proc_fops) {
	250	spin_unlock(&pde->pde_unload_lock);
	251	return rv;
	252	}
	253	pde->pde_users++;
	254	compat_ioctl = pde->proc_fops->compat_ioctl;
	255	spin_unlock(&pde->pde_unload_lock);
	256
	257	if (compat_ioctl)
	258	rv = compat_ioctl(file, cmd, arg);
	259
	260	pde_users_dec(pde);
	261	return rv;
	262	}
	263	#endif
	264
	265	static int proc_reg_mmap(struct file file, struct vm_area_struct vma)
	266	{
	267	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	268	int rv = -EIO;
	269	int (mmap)(struct file , struct vm_area_struct *);
	270
	271	spin_lock(&pde->pde_unload_lock);
	272	if (!pde->proc_fops) {
	273	spin_unlock(&pde->pde_unload_lock);
	274	return rv;
	275	}
	276	pde->pde_users++;
	277	mmap = pde->proc_fops->mmap;
	278	spin_unlock(&pde->pde_unload_lock);
	279
	280	if (mmap)
	281	rv = mmap(file, vma);
	282
	283	pde_users_dec(pde);
	284	return rv;
	285	}
	286
	287	static int proc_reg_open(struct inode inode, struct file file)
	288	{
	289	struct proc_dir_entry *pde = PDE(inode);
	290	int rv = 0;
	291	int (open)(struct inode , struct file *);
	292	int (release)(struct inode , struct file *);
	293	struct pde_opener *pdeo;
	294
	295	/*
	296	* What for, you ask? Well, we can have open, rmmod, remove_proc_entry
	297	* sequence. ->release won't be called because ->proc_fops will be
	298	* cleared. Depending on complexity of ->release, consequences vary.
	299	*
	300	* We can't wait for mercy when close will be done for real, it's
	301	* deadlockable: rmmod foo </proc/foo . So, we're going to do ->release
	302	* by hand in remove_proc_entry(). For this, save opener's credentials
	303	* for later.
	304	*/
	305	pdeo = kmalloc(sizeof(struct pde_opener), GFP_KERNEL);
	306	if (!pdeo)
	307	return -ENOMEM;
	308
	309	spin_lock(&pde->pde_unload_lock);
	310	if (!pde->proc_fops) {
	311	spin_unlock(&pde->pde_unload_lock);
	312	kfree(pdeo);
	313	return -EINVAL;
	314	}
	315	pde->pde_users++;
	316	open = pde->proc_fops->open;
	317	release = pde->proc_fops->release;
	318	spin_unlock(&pde->pde_unload_lock);
	319
	320	if (open)
	321	rv = open(inode, file);
	322
	323	spin_lock(&pde->pde_unload_lock);
	324	if (rv == 0 && release) {
	325	/* To know what to release. */
	326	pdeo->inode = inode;
	327	pdeo->file = file;
	328	/* Strictly for "too late" ->release in proc_reg_release(). */
	329	pdeo->release = release;
	330	list_add(&pdeo->lh, &pde->pde_openers);
	331	} else
	332	kfree(pdeo);
	333	__pde_users_dec(pde);
	334	spin_unlock(&pde->pde_unload_lock);
	335	return rv;
	336	}
	337
	338	static struct pde_opener find_pde_opener(struct proc_dir_entry pde,
	339	struct inode inode, struct file file)
	340	{
	341	struct pde_opener *pdeo;
	342
	343	list_for_each_entry(pdeo, &pde->pde_openers, lh) {
	344	if (pdeo->inode == inode && pdeo->file == file)
	345	return pdeo;
	346	}
	347	return NULL;
	348	}
	349
	350	static int proc_reg_release(struct inode inode, struct file file)
	351	{
	352	struct proc_dir_entry *pde = PDE(inode);
	353	int rv = 0;
	354	int (release)(struct inode , struct file *);
	355	struct pde_opener *pdeo;
	356
	357	spin_lock(&pde->pde_unload_lock);
	358	pdeo = find_pde_opener(pde, inode, file);
	359	if (!pde->proc_fops) {
	360	/*
	361	* Can't simply exit, __fput() will think that everything is OK,
	362	* and move on to freeing struct file. remove_proc_entry() will
	363	* find slacker in opener's list and will try to do non-trivial
	364	* things with struct file. Therefore, remove opener from list.
	365	*
	366	* But if opener is removed from list, who will ->release it?
	367	*/
	368	if (pdeo) {
	369	list_del(&pdeo->lh);
	370	spin_unlock(&pde->pde_unload_lock);
	371	rv = pdeo->release(inode, file);
	372	kfree(pdeo);
	373	} else
	374	spin_unlock(&pde->pde_unload_lock);
	375	return rv;
	376	}
	377	pde->pde_users++;
	378	release = pde->proc_fops->release;
	379	if (pdeo) {
	380	list_del(&pdeo->lh);
	381	kfree(pdeo);
	382	}
	383	spin_unlock(&pde->pde_unload_lock);
	384
	385	if (release)
	386	rv = release(inode, file);
	387
	388	pde_users_dec(pde);
	389	return rv;
	390	}
	391
	392	static const struct file_operations proc_reg_file_ops = {
	393	.llseek = proc_reg_llseek,
	394	.read = proc_reg_read,
	395	.write = proc_reg_write,
	396	.poll = proc_reg_poll,
	397	.unlocked_ioctl = proc_reg_unlocked_ioctl,
	398	#ifdef CONFIG_COMPAT
	399	.compat_ioctl = proc_reg_compat_ioctl,
	400	#endif
	401	.mmap = proc_reg_mmap,
	402	.open = proc_reg_open,
	403	.release = proc_reg_release,
	404	};
	405
	406	#ifdef CONFIG_COMPAT
	407	static const struct file_operations proc_reg_file_ops_no_compat = {
	408	.llseek = proc_reg_llseek,
	409	.read = proc_reg_read,
	410	.write = proc_reg_write,
	411	.poll = proc_reg_poll,
	412	.unlocked_ioctl = proc_reg_unlocked_ioctl,
	413	.mmap = proc_reg_mmap,
	414	.open = proc_reg_open,
	415	.release = proc_reg_release,
	416	};
	417	#endif
	418
	419	struct inode proc_get_inode(struct super_block sb, struct proc_dir_entry *de)
	420	{
	421	struct inode * inode;
	422
	423	inode = iget_locked(sb, de->low_ino);
	424	if (!inode)
	425	return NULL;
	426	if (inode->i_state & I_NEW) {
	427	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	428	PROC_I(inode)->fd = 0;
	429	PROC_I(inode)->pde = de;
	430
	431	if (de->mode) {
	432	inode->i_mode = de->mode;
	433	inode->i_uid = de->uid;
	434	inode->i_gid = de->gid;
	435	}
	436	if (de->size)
	437	inode->i_size = de->size;
	438	if (de->nlink)
	439	inode->i_nlink = de->nlink;
	440	if (de->proc_iops)
	441	inode->i_op = de->proc_iops;
	442	if (de->proc_fops) {
	443	if (S_ISREG(inode->i_mode)) {
	444	#ifdef CONFIG_COMPAT
	445	if (!de->proc_fops->compat_ioctl)
	446	inode->i_fop =
	447	&proc_reg_file_ops_no_compat;
	448	else
	449	#endif
	450	inode->i_fop = &proc_reg_file_ops;
	451	} else {
	452	inode->i_fop = de->proc_fops;
	453	}
	454	}
	455	unlock_new_inode(inode);
	456	} else
	457	pde_put(de);
	458	return inode;
	459	}
	460
	461	int proc_fill_super(struct super_block *s)
	462	{
	463	struct inode * root_inode;
	464
	465	s->s_flags \|= MS_NODIRATIME \| MS_NOSUID \| MS_NOEXEC;
	466	s->s_blocksize = 1024;
	467	s->s_blocksize_bits = 10;
	468	s->s_magic = PROC_SUPER_MAGIC;
	469	s->s_op = &proc_sops;
	470	s->s_time_gran = 1;
	471
	472	pde_get(&proc_root);
	473	root_inode = proc_get_inode(s, &proc_root);
	474	if (!root_inode)
	475	goto out_no_root;
	476	root_inode->i_uid = 0;
	477	root_inode->i_gid = 0;
	478	s->s_root = d_alloc_root(root_inode);
	479	if (!s->s_root)
	480	goto out_no_root;
	481	return 0;
	482
	483	out_no_root:
	484	printk("proc_read_super: get root inode failed\n");
	485	iput(root_inode);
	486	pde_put(&proc_root);
	487	return -ENOMEM;
	488	}