/*
   *  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/file.h>
  #include <linux/limits.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/smp_lock.h>
  
  #include <asm/system.h>
  #include <asm/uaccess.h>

  #include "internal.h"

  struct proc_dir_entry *de_get(struct proc_dir_entry *de)

  {
  	if (de)
  		atomic_inc(&de->count);
  	return de;
  }
  
  /*
   * Decrements the use count and checks for deferred deletion.
   */

  void de_put(struct proc_dir_entry *de)

  {
  	if (de) {	
  		lock_kernel();		
  		if (!atomic_read(&de->count)) {
  			printk("de_put: entry %s already free!
  ", de->name);
  			unlock_kernel();
  			return;
  		}
  
  		if (atomic_dec_and_test(&de->count)) {
  			if (de->deleted) {
  				printk("de_put: deferred delete of %s
  ",
  					de->name);
  				free_proc_entry(de);
  			}
  		}		
  		unlock_kernel();
  	}
  }
  
  /*
   * Decrement the use count of the proc_dir_entry.
   */
  static void proc_delete_inode(struct inode *inode)
  {
  	struct proc_dir_entry *de;

  	truncate_inode_pages(&inode->i_data, 0);

  	/* 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) {
  		if (de->owner)
  			module_put(de->owner);
  		de_put(de);
  	}
  	clear_inode(inode);
  }
  
  struct vfsmount *proc_mnt;
  
  static void proc_read_inode(struct inode * inode)
  {
  	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  }

  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;
  	inode = &ei->vfs_inode;
  	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  	return inode;
  }
  
  static void proc_destroy_inode(struct inode *inode)
  {
  	kmem_cache_free(proc_inode_cachep, PROC_I(inode));
  }

  static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flags)

  {
  	struct proc_inode *ei = (struct proc_inode *) foo;

  	inode_init_once(&ei->vfs_inode);

  }

  int __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),

  					     init_once);

  	if (proc_inode_cachep == NULL)
  		return -ENOMEM;
  	return 0;
  }
  
  static int proc_remount(struct super_block *sb, int *flags, char *data)
  {
  	*flags |= MS_NODIRATIME;
  	return 0;
  }

  static const struct super_operations proc_sops = {

  	.alloc_inode	= proc_alloc_inode,
  	.destroy_inode	= proc_destroy_inode,
  	.read_inode	= proc_read_inode,
  	.drop_inode	= generic_delete_inode,
  	.delete_inode	= proc_delete_inode,
  	.statfs		= simple_statfs,
  	.remount_fs	= proc_remount,
  };

  static void pde_users_dec(struct proc_dir_entry *pde)
  {
  	spin_lock(&pde->pde_unload_lock);
  	pde->pde_users--;
  	if (pde->pde_unload_completion && pde->pde_users == 0)
  		complete(pde->pde_unload_completion);
  	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 = 0;
  	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 (*unlocked_ioctl)(struct file *, unsigned int, unsigned long);
  	int (*ioctl)(struct inode *, 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++;
  	unlocked_ioctl = pde->proc_fops->unlocked_ioctl;
  	ioctl = pde->proc_fops->ioctl;
  	spin_unlock(&pde->pde_unload_lock);
  
  	if (unlocked_ioctl) {
  		rv = unlocked_ioctl(file, cmd, arg);
  		if (rv == -ENOIOCTLCMD)
  			rv = -EINVAL;
  	} else if (ioctl) {
  		lock_kernel();
  		rv = ioctl(file->f_path.dentry->d_inode, file, cmd, arg);
  		unlock_kernel();
  	}
  
  	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 *);
  
  	spin_lock(&pde->pde_unload_lock);
  	if (!pde->proc_fops) {
  		spin_unlock(&pde->pde_unload_lock);
  		return rv;
  	}
  	pde->pde_users++;
  	open = pde->proc_fops->open;
  	spin_unlock(&pde->pde_unload_lock);
  
  	if (open)
  		rv = open(inode, file);
  
  	pde_users_dec(pde);
  	return rv;
  }
  
  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 *);
  
  	spin_lock(&pde->pde_unload_lock);
  	if (!pde->proc_fops) {
  		spin_unlock(&pde->pde_unload_lock);
  		return rv;
  	}
  	pde->pde_users++;
  	release = pde->proc_fops->release;
  	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,
  };

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

  	if (de != NULL && !try_module_get(de->owner))
  		goto out_mod;

  	inode = iget(sb, ino);
  	if (!inode)

  		goto out_ino;

  	PROC_I(inode)->fd = 0;

  	PROC_I(inode)->pde = de;
  	if (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))
  				inode->i_fop = &proc_reg_file_ops;
  			else
  				inode->i_fop = de->proc_fops;
  		}

  	}

  	return inode;

  out_ino:
  	if (de != NULL)
  		module_put(de->owner);
  out_mod:

  	return NULL;

  }			
  
  int proc_fill_super(struct super_block *s, void *data, int silent)
  {
  	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;
  	

  	de_get(&proc_root);

  	root_inode = proc_get_inode(s, PROC_ROOT_INO, &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
  ");
  	iput(root_inode);

  	de_put(&proc_root);

  	return -ENOMEM;
  }
  MODULE_LICENSE("GPL");