patch-2.3.27 linux/fs/proc/base.c

• Lines: 1150
• Date: Mon Nov 8 14:28:34 1999
• Orig file: v2.3.26/linux/fs/proc/base.c
• Orig date: Tue Aug 31 17:29:14 1999

diff -u --recursive --new-file v2.3.26/linux/fs/proc/base.c linux/fs/proc/base.c
@@ -4,6 +4,13 @@
  *  Copyright (C) 1991, 1992 Linus Torvalds
  *
  *  proc base directory handling functions
+ *
+ *  1999, Al Viro. Rewritten. Now it covers the whole per-process part.
+ *  Instead of using magical inumbers to determine the kind of object
+ *  we allocate and fill in-core inodes upon lookup. They don't even
+ *  go into icache. We cache the reference to task_struct upon lookup too.
+ *  Eventually it should become a filesystem in its own. We don't use the
+ *  rest of procfs anymore.
  */
 
 #include <asm/uaccess.h>
@@ -14,28 +21,336 @@
 #include <linux/proc_fs.h>
 #include <linux/stat.h>
 #include <linux/init.h>
-
-static struct file_operations proc_base_operations = {
-	NULL,			/* lseek - default */
-	NULL,			/* read - bad */
-	NULL,			/* write - bad */
-	proc_readdir,		/* readdir */
-	NULL,			/* poll - default */
-	NULL,			/* ioctl - default */
-	NULL,			/* mmap */
-	NULL,			/* no special open code */
-	NULL,			/* flush */
-	NULL,			/* no special release code */
-	NULL			/* can't fsync */
-};
+#include <linux/file.h>
 
 /*
- * proc directories can do almost nothing..
+ * For hysterical raisins we keep the same inumbers as in the old procfs.
+ * Feel free to change the macro below - just keep the range distinct from
+ * inumbers of the rest of procfs (currently those are in 0x0000--0xffff).
+ * As soon as we'll get a separate superblock we will be able to forget
+ * about magical ranges too.
  */
-static struct inode_operations proc_base_inode_operations = {
-	&proc_base_operations,	/* default base directory file-ops */
+
+#define fake_ino(pid,ino) (((pid)<<16)|(ino))
+
+ssize_t proc_pid_read_maps(struct task_struct*,struct file*,char*,size_t,loff_t*);
+int proc_pid_stat(struct task_struct*,char*);
+int proc_pid_status(struct task_struct*,char*);
+int proc_pid_statm(struct task_struct*,char*);
+int proc_pid_cpu(struct task_struct*,char*);
+
+static struct dentry *proc_fd_link(struct inode *inode)
+{
+	if (inode->u.proc_i.file)
+		return dget(inode->u.proc_i.file->f_dentry);
+	return NULL;
+}
+
+static struct dentry *proc_exe_link(struct inode *inode)
+{
+	struct mm_struct * mm;
+	struct vm_area_struct * vma;
+	struct dentry *result = NULL;
+	struct task_struct *task = inode->u.proc_i.task;
+
+	if (!task_lock(task))
+		return NULL;
+	mm = task->mm;
+	if (!mm)
+		goto out;
+	down(&mm->mmap_sem);
+	vma = mm->mmap;
+	while (vma) {
+		if ((vma->vm_flags & VM_EXECUTABLE) && 
+		    vma->vm_file) {
+			result = dget(vma->vm_file->f_dentry);
+			break;
+		}
+		vma = vma->vm_next;
+	}
+	up(&mm->mmap_sem);
+out:
+	task_unlock(task);
+	return result;
+}
+
+static struct dentry *proc_cwd_link(struct inode *inode)
+{
+	struct dentry *result = NULL;
+	if (task_lock(inode->u.proc_i.task)) {
+		struct fs_struct *fs = inode->u.proc_i.task->fs;
+		if (fs)
+			result = dget(fs->pwd);
+		task_unlock(inode->u.proc_i.task);
+	}
+	return result;
+}
+
+static struct dentry *proc_root_link(struct inode *inode)
+{
+	struct dentry *result = NULL;
+	if (task_lock(inode->u.proc_i.task)) {
+		struct fs_struct *fs = inode->u.proc_i.task->fs;
+		if (fs)
+			result = dget(fs->root);
+		task_unlock(inode->u.proc_i.task);
+	}
+	return result;
+}
+
+/* task is locked and can't drop mm, so we are safe */
+
+static int proc_pid_environ(struct task_struct *task, char * buffer)
+{
+	struct mm_struct *mm = task->mm;
+	int res = 0;
+	if (mm)
+		res = access_process_vm(task, mm->env_start, buffer,
+					mm->env_end - mm->env_start, 0);
+	return res;
+}
+
+/* task is locked and can't drop mm, so we are safe */
+
+static int proc_pid_cmdline(struct task_struct *task, char * buffer)
+{
+	struct mm_struct *mm = task->mm;
+	int res = 0;
+	if (mm)
+		res = access_process_vm(task, mm->arg_start, buffer,
+					mm->arg_end - mm->arg_start, 0);
+	return res;
+}
+
+/************************************************************************/
+/*                       Here the fs part begins                        */
+/************************************************************************/
+
+/* permission checks */
+
+static int standard_permission(struct inode *inode, int mask)
+{
+	int mode = inode->i_mode;
+
+	if ((mask & S_IWOTH) && IS_RDONLY(inode) &&
+	    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
+		return -EROFS; /* Nobody gets write access to a read-only fs */
+	else if ((mask & S_IWOTH) && IS_IMMUTABLE(inode))
+		return -EACCES; /* Nobody gets write access to an immutable file */
+	else if (current->fsuid == inode->i_uid)
+		mode >>= 6;
+	else if (in_group_p(inode->i_gid))
+		mode >>= 3;
+	if (((mode & mask & S_IRWXO) == mask) || capable(CAP_DAC_OVERRIDE))
+		return 0;
+	/* read and search access */
+	if ((mask == S_IROTH) ||
+	    (S_ISDIR(mode)  && !(mask & ~(S_IROTH | S_IXOTH))))
+		if (capable(CAP_DAC_READ_SEARCH))
+			return 0;
+	return -EACCES;
+}
+
+static int proc_permission(struct inode *inode, int mask)
+{
+	struct dentry *de, *base, *root;
+	struct super_block *our_sb, *sb, *below;
+
+	if (standard_permission(inode, mask) != 0)
+		return -EACCES;
+
+	base = current->fs->root;
+	de = root = proc_root_link(inode); /* Ewww... */
+
+	if (!de)
+		return -ENOENT;
+
+	our_sb = base->d_inode->i_sb;
+	sb = de->d_inode->i_sb;
+	while (sb != our_sb) {
+		de = sb->s_root->d_covers;
+		below = de->d_inode->i_sb;
+		if (sb == below)
+			goto out;
+		sb = below;
+	}
+
+	if (!is_subdir(de, base))
+		goto out;
+
+	dput(root);
+	return 0;
+out:
+	dput(root);
+	return -EACCES;
+}
+
+static ssize_t pid_maps_read(struct file * file, char * buf,
+			      size_t count, loff_t *ppos)
+{
+	struct inode * inode = file->f_dentry->d_inode;
+	struct task_struct *task = inode->u.proc_i.task;
+	ssize_t res;
+
+	if (!task_lock(task))
+		return -EIO;
+	res = proc_pid_read_maps(task, file, buf, count, ppos);
+	task_unlock(task);
+	return res;
+}
+
+static struct file_operations proc_maps_operations = {
+	NULL,		/* array_lseek */
+	pid_maps_read,
+};
+
+struct inode_operations proc_maps_inode_operations = {
+	&proc_maps_operations,	/* default base directory file-ops */
+};
+
+#define PROC_BLOCK_SIZE	(3*1024)		/* 4K page size but our output routines use some slack for overruns */
+
+static ssize_t proc_info_read(struct file * file, char * buf,
+			  size_t count, loff_t *ppos)
+{
+	struct inode * inode = file->f_dentry->d_inode;
+	unsigned long page;
+	ssize_t length;
+	ssize_t end;
+	struct task_struct *task = inode->u.proc_i.task;
+
+	if (count > PROC_BLOCK_SIZE)
+		count = PROC_BLOCK_SIZE;
+	if (!(page = __get_free_page(GFP_KERNEL)))
+		return -ENOMEM;
+
+	if (!task_lock(task)) {
+		free_page(page);
+		return -EIO;
+	}
+	
+	length = inode->u.proc_i.op.proc_read(task, (char*)page);
+
+	task_unlock(task);
+
+	if (length < 0) {
+		free_page(page);
+		return length;
+	}
+	/* Static 4kB (or whatever) block capacity */
+	if (*ppos >= length) {
+		free_page(page);
+		return 0;
+	}
+	if (count + *ppos > length)
+		count = length - *ppos;
+	end = count + *ppos;
+	copy_to_user(buf, (char *) page + *ppos, count);
+	*ppos = end;
+	free_page(page);
+	return count;
+}
+
+static struct file_operations proc_info_file_operations = {
+    NULL,			/* lseek   */
+    proc_info_read,		/* read	   */
+};
+
+static struct inode_operations proc_info_inode_operations = {
+	&proc_info_file_operations,  /* default proc file-ops */
+};
+
+#define MAY_PTRACE(p) \
+(p==current||(p->p_pptr==current&&(p->flags&PF_PTRACED)&&p->state==TASK_STOPPED))
+
+static ssize_t mem_read(struct file * file, char * buf,
+			size_t count, loff_t *ppos)
+{
+	struct task_struct *task = file->f_dentry->d_inode->u.proc_i.task;
+	char *page;
+	unsigned long src = *ppos;
+	int copied = 0;
+
+	if (!MAY_PTRACE(task))
+		return -ESRCH;
+
+	page = (char *)__get_free_page(GFP_USER);
+	if (!page)
+		return -ENOMEM;
+
+	while (count > 0) {
+		int this_len, retval;
+
+		this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
+		retval = access_process_vm(task, src, page, this_len, 0);
+		if (!retval) {
+			if (!copied)
+				copied = -EIO;
+			break;
+		}
+		if (copy_to_user(buf, page, retval)) {
+			copied = -EFAULT;
+			break;
+		}
+		copied += retval;
+		src += retval;
+		buf += retval;
+		count -= retval;
+	}
+	*ppos = src;
+	free_page((unsigned long) page);
+	return copied;
+}
+
+static ssize_t mem_write(struct file * file, const char * buf,
+			 size_t count, loff_t *ppos)
+{
+	int copied = 0;
+	char *page;
+	struct task_struct *task = file->f_dentry->d_inode->u.proc_i.task;
+	unsigned long dst = *ppos;
+
+	if (!MAY_PTRACE(task))
+		return -ESRCH;
+
+	page = (char *)__get_free_page(GFP_USER);
+	if (!page)
+		return -ENOMEM;
+
+	while (count > 0) {
+		int this_len, retval;
+
+		this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
+		if (copy_from_user(page, buf, this_len)) {
+			copied = -EFAULT;
+			break;
+		}
+		retval = access_process_vm(task, dst, page, this_len, 1);
+		if (!retval) {
+			if (!copied)
+				copied = -EIO;
+			break;
+		}
+		copied += retval;
+		buf += retval;
+		dst += retval;
+		count -= retval;			
+	}
+	*ppos = dst;
+	free_page((unsigned long) page);
+	return copied;
+}
+
+static struct file_operations proc_mem_operations = {
+	NULL,		/* lseek - default */
+	mem_read,
+	mem_write,
+};
+
+static struct inode_operations proc_mem_inode_operations = {
+	&proc_mem_operations,	/* default base directory file-ops */
 	NULL,			/* create */
-	proc_lookup,		/* lookup */
+	NULL,			/* lookup */
 	NULL,			/* link */
 	NULL,			/* unlink */
 	NULL,			/* symlink */
@@ -50,161 +365,653 @@
 	NULL,			/* writepage */
 	NULL,			/* flushpage */
 	NULL,			/* truncate */
-	NULL,			/* permission */
+	proc_permission,	/* permission */
 	NULL,			/* smap */
 	NULL			/* revalidate */
 };
 
-/*
- * The fill argument is non-zero when the inode is being filled ...
- * we don't need to do anything when it's being deleted.
- */
-static void proc_pid_fill_inode(struct inode * inode, int fill)
+static struct dentry * proc_pid_follow_link(struct dentry *dentry,
+					struct dentry *base,
+					unsigned int follow)
 {
-	struct task_struct *p;
-	int pid = inode->i_ino >> 16;
-	int ino = inode->i_ino & 0xffff;
+	struct inode *inode = dentry->d_inode;
+	struct dentry * result;
+	int error;
+
+	/* We don't need a base pointer in the /proc filesystem */
+	dput(base);
+
+	error = proc_permission(inode, MAY_EXEC);
+	result = ERR_PTR(error);
+	if (error)
+		goto out;
+
+	result = inode->u.proc_i.op.proc_get_link(inode);
+out:
+	if (!result)
+		result = ERR_PTR(-ENOENT);
+	return result;
+}
 
-	read_lock(&tasklist_lock);
-	if (fill && (p = find_task_by_pid(pid)) != NULL) {
-		uid_t uid = 0;
-		gid_t gid = 0;
-		if (p->dumpable || ino == PROC_PID_INO) {
-			uid = p->euid;
-			gid = p->egid;
-		}
-		inode->i_uid = uid;
-		inode->i_gid = gid;
+static int do_proc_readlink(struct dentry *dentry, char * buffer, int buflen)
+{
+	struct inode * inode;
+	char * tmp = (char*)__get_free_page(GFP_KERNEL), *path, *pattern;
+	int len;
+
+	if (!tmp)
+		return -ENOMEM;
+		
+	/* Check for special dentries.. */
+	pattern = NULL;
+	inode = dentry->d_inode;
+	if (inode && IS_ROOT(dentry)) {
+		if (S_ISSOCK(inode->i_mode))
+			pattern = "socket:[%lu]";
+		if (S_ISFIFO(inode->i_mode))
+			pattern = "pipe:[%lu]";
 	}
-	read_unlock(&tasklist_lock);
+	
+	if (pattern) {
+		len = sprintf(tmp, pattern, inode->i_ino);
+		path = tmp;
+	} else {
+		path = d_path(dentry, tmp, PAGE_SIZE);
+		len = tmp + PAGE_SIZE - 1 - path;
+	}
+
+	if (len < buflen)
+		buflen = len;
+	copy_to_user(buffer, path, buflen);
+	free_page((unsigned long)tmp);
+	return buflen;
 }
 
-/*
- * This is really a pseudo-entry, and only links
- * backwards to the parent with no link from the
- * root directory to this. This way we can have just
- * one entry for every /proc/<pid>/ directory.
- */
-struct proc_dir_entry proc_pid = {
-	PROC_PID_INO, 5, "<pid>",
-	S_IFDIR | S_IRUGO | S_IXUGO, 2, 0, 0,
-	0, &proc_base_inode_operations,
-	NULL, proc_pid_fill_inode,
-	NULL, &proc_root, NULL
-};
-
-static struct proc_dir_entry proc_pid_status = {
-	PROC_PID_STATUS, 6, "status",
-	S_IFREG | S_IRUGO, 1, 0, 0,
-	0, &proc_array_inode_operations,
-	NULL, proc_pid_fill_inode,
-};
-static struct proc_dir_entry proc_pid_mem = {
-	PROC_PID_MEM, 3, "mem",
-	S_IFREG | S_IRUSR | S_IWUSR, 1, 0, 0,
-	0, &proc_mem_inode_operations,
-	NULL, proc_pid_fill_inode,
-};
-static struct proc_dir_entry proc_pid_cwd = {
-	PROC_PID_CWD, 3, "cwd",
-	S_IFLNK | S_IRWXU, 1, 0, 0,
-	0, &proc_link_inode_operations,
-	NULL, proc_pid_fill_inode,
-};
-static struct proc_dir_entry proc_pid_root = {
-	PROC_PID_ROOT, 4, "root",
-	S_IFLNK | S_IRWXU, 1, 0, 0,
-	0, &proc_link_inode_operations,
-	NULL, proc_pid_fill_inode,
-};
-static struct proc_dir_entry proc_pid_exe = {
-	PROC_PID_EXE, 3, "exe",
-	S_IFLNK | S_IRWXU, 1, 0, 0,
-	0, &proc_link_inode_operations,
-	NULL, proc_pid_fill_inode,
-};
-static struct proc_dir_entry proc_pid_fd = {
-	PROC_PID_FD, 2, "fd",
-	S_IFDIR | S_IRUSR | S_IXUSR, 2, 0, 0,
-	0, &proc_fd_inode_operations,
-	NULL, proc_pid_fill_inode,
-};
-static struct proc_dir_entry proc_pid_environ = {
-	PROC_PID_ENVIRON, 7, "environ",
-	S_IFREG | S_IRUSR, 1, 0, 0,
-	0, &proc_array_inode_operations,
-	NULL, proc_pid_fill_inode,
-};
-static struct proc_dir_entry proc_pid_cmdline = {
-	PROC_PID_CMDLINE, 7, "cmdline",
-	S_IFREG | S_IRUGO, 1, 0, 0,
-	0, &proc_array_inode_operations,
-	NULL, proc_pid_fill_inode,
-};
-static struct proc_dir_entry proc_pid_stat = {
-	PROC_PID_STAT, 4, "stat",
-	S_IFREG | S_IRUGO, 1, 0, 0,
-	0, &proc_array_inode_operations,
-	NULL, proc_pid_fill_inode,
-};
-static struct proc_dir_entry proc_pid_statm = {
-	PROC_PID_STATM, 5, "statm",
-	S_IFREG | S_IRUGO, 1, 0, 0,
-	0, &proc_array_inode_operations,
-	NULL, proc_pid_fill_inode,
-};
-static struct proc_dir_entry proc_pid_maps = {
-	PROC_PID_MAPS, 4, "maps",
-	S_IFIFO | S_IRUGO, 1, 0, 0,
-	0, &proc_arraylong_inode_operations,
-	NULL, proc_pid_fill_inode,
+static int proc_pid_readlink(struct dentry * dentry, char * buffer, int buflen)
+{
+	int error;
+	struct inode *inode = dentry->d_inode;
+
+	error = proc_permission(inode, MAY_EXEC);
+	if (error)
+		goto out;
+
+	dentry = inode->u.proc_i.op.proc_get_link(inode);
+	error = -ENOENT;
+	if (!dentry)
+		goto out;
+
+	error = PTR_ERR(dentry);
+	if (IS_ERR(dentry))
+		goto out;
+
+	error = do_proc_readlink(dentry, buffer, buflen);
+	dput(dentry);
+out:
+	return error;
+}
+
+static struct inode_operations proc_pid_link_inode_operations = {
+	NULL,			/* file-operations */
+	NULL,			/* create */
+	NULL,			/* lookup */
+	NULL,			/* link */
+	NULL,			/* unlink */
+	NULL,			/* symlink */
+	NULL,			/* mkdir */
+	NULL,			/* rmdir */
+	NULL,			/* mknod */
+	NULL,			/* rename */
+	proc_pid_readlink,	/* readlink */
+	proc_pid_follow_link,	/* follow_link */
 };
 
+/* reading from directory - bad */
+
+static ssize_t proc_dir_read (struct file * filp, char * buf,
+			      size_t count, loff_t *ppos)
+{
+	return -EISDIR;
+}
+
+struct pid_entry {
+	int type;
+	int len;
+	char *name;
+	mode_t mode;
+};
+
+enum pid_directory_inos {
+	PROC_PID_INO = 2,
+	PROC_PID_STATUS,
+	PROC_PID_MEM,
+	PROC_PID_CWD,
+	PROC_PID_ROOT,
+	PROC_PID_EXE,
+	PROC_PID_FD,
+	PROC_PID_ENVIRON,
+	PROC_PID_CMDLINE,
+	PROC_PID_STAT,
+	PROC_PID_STATM,
+	PROC_PID_MAPS,
 #if CONFIG_AP1000
-static struct proc_dir_entry proc_pid_ringbuf = {
-	PROC_PID_RINGBUF, 7, "ringbuf",
-	S_IFREG | S_IRUGO | S_IWUSR, 1, 0, 0,
-	0, &proc_ringbuf_inode_operations,
-	NULL, proc_pid_fill_inode,
+	PROC_PID_RINGBUF,
+#endif
+	PROC_PID_CPU,
+	PROC_PID_FD_DIR = 0x8000,	/* 0x8000-0xffff */
 };
+
+#define E(type,name,mode) {(type),sizeof(name)-1,(name),(mode)}
+static struct pid_entry base_stuff[] = {
+  E(PROC_PID_FD,	"fd",		S_IFDIR|S_IRUSR|S_IXUSR),
+  E(PROC_PID_ENVIRON,	"environ",	S_IFREG|S_IRUSR),
+  E(PROC_PID_STATUS,	"status",	S_IFREG|S_IRUGO),
+  E(PROC_PID_CMDLINE,	"cmdline",	S_IFREG|S_IRUGO),
+  E(PROC_PID_STAT,	"stat",		S_IFREG|S_IRUGO),
+  E(PROC_PID_STATM,	"statm",	S_IFREG|S_IRUGO),
+#ifdef SMP
+  E(PROC_PID_CPU,	"cpu",		S_IFREG|S_IRUGO),
+#endif
+#if CONFIG_AP1000
+  E(PROC_PID_RINGBUF,	"ringbuf",	S_IFREG|S_IRUGO|S_IWUSR),
 #endif
+  E(PROC_PID_MAPS,	"maps",		S_IFREG|S_IRUGO),
+  E(PROC_PID_MEM,	"mem",		S_IFREG|S_IRUSR|S_IWUSR),
+  E(PROC_PID_CWD,	"cwd",		S_IFLNK|S_IRWXUGO),
+  E(PROC_PID_ROOT,	"root",		S_IFLNK|S_IRWXUGO),
+  E(PROC_PID_EXE,	"exe",		S_IFLNK|S_IRWXUGO),
+  {0,0,NULL,0}
+};
+#undef E
+
+#define NUMBUF 10
+
+static int proc_readfd(struct file * filp, void * dirent, filldir_t filldir)
+{
+	struct inode *inode = filp->f_dentry->d_inode;
+	struct task_struct *p = inode->u.proc_i.task;
+	unsigned int fd, pid, ino;
+	int retval;
+	char buf[NUMBUF];
+
+	retval = 0;
+	pid = p->pid;
+
+	fd = filp->f_pos;
+	switch (fd) {
+		case 0:
+			if (filldir(dirent, ".", 1, 0, inode->i_ino) < 0)
+				goto out;
+			filp->f_pos++;
+		case 1:
+			ino = fake_ino(pid, PROC_PID_INO);
+			if (filldir(dirent, "..", 2, 1, ino) < 0)
+				goto out;
+			filp->f_pos++;
+		default:
+			for (fd = filp->f_pos-2;
+			     p->p_pptr && p->files && fd < p->files->max_fds;
+			     fd++, filp->f_pos++) {
+				unsigned int i,j;
+
+				if (!fcheck_task(p, fd))
+					continue;
+
+				j = NUMBUF;
+				i = fd;
+				do {
+					j--;
+					buf[j] = '0' + (i % 10);
+					i /= 10;
+				} while (i);
+
+				ino = fake_ino(pid, PROC_PID_FD_DIR + fd);
+				if (filldir(dirent, buf+j, NUMBUF-j, fd+2, ino) < 0)
+					break;
+
+			}
+	}
+out:
+	return retval;
+}
+
+static int proc_base_readdir(struct file * filp,
+	void * dirent, filldir_t filldir)
+{
+	int i;
+	int pid;
+	struct inode *inode = filp->f_dentry->d_inode;
+	struct pid_entry *p;
+
+	pid = inode->u.proc_i.task->pid;
+	if (!inode->u.proc_i.task->p_pptr)
+		return -ENOENT;
+	i = filp->f_pos;
+	switch (i) {
+		case 0:
+			if (filldir(dirent, ".", 1, i, inode->i_ino) < 0)
+				return 0;
+			i++;
+			filp->f_pos++;
+			/* fall through */
+		case 1:
+			if (filldir(dirent, "..", 2, i, PROC_ROOT_INO) < 0)
+				return 0;
+			i++;
+			filp->f_pos++;
+			/* fall through */
+		default:
+			i -= 2;
+			if (i>=sizeof(base_stuff)/sizeof(base_stuff[0]))
+				return 1;
+			p = base_stuff + i;
+			while (p->name) {
+				if (filldir(dirent, p->name, p->len, filp->f_pos, fake_ino(pid, p->type)) < 0)
+					return 0;
+				filp->f_pos++;
+				p++;
+			}
+	}
+	return 1;
+}
+
+/* building an inode */
+
+static struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task, int ino)
+{
+	struct inode * inode;
+
+	/* We need a new inode */
+	
+	inode = get_empty_inode();
+	if (!inode)
+		goto out;
+
+	/* Common stuff */
+
+	inode->i_sb = sb;
+	inode->i_dev = sb->s_dev;
+	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+	inode->i_ino = fake_ino(task->pid, ino);
+
+	inode->u.proc_i.file = NULL;
+	/*
+	 * grab the reference to task.
+	 */
+	inode->u.proc_i.task = task;
+	atomic_inc(&mem_map[MAP_NR(task)].count);
+	if (!task->p_pptr)
+		goto out_unlock;
+
+	inode->i_uid = 0;
+	inode->i_gid = 0;
+	if (ino == PROC_PID_INO || task->dumpable) {
+		inode->i_uid = task->euid;
+		inode->i_gid = task->egid;
+	}
+
+out:
+	return inode;
+
+out_unlock:
+	iput(inode);
+	return NULL;
+}
 
-#ifdef __SMP__
-static struct proc_dir_entry proc_pid_cpu = {
-	PROC_PID_CPU, 3, "cpu",
-	S_IFREG | S_IRUGO, 1, 0, 0,
-	0, &proc_array_inode_operations,
-	NULL, proc_pid_fill_inode,
+/* dentry stuff */
+
+static int pid_fd_revalidate(struct dentry * dentry, int flags)
+{
+	return 0;
+}
+
+static int pid_base_revalidate(struct dentry * dentry, int flags)
+{
+	if (dentry->d_inode->u.proc_i.task->p_pptr)
+		return 1;
+	d_drop(dentry);
+	return 0;
+}
+
+static void pid_delete_dentry(struct dentry * dentry)
+{
+	d_drop(dentry);
+}
+
+static struct dentry_operations pid_fd_dentry_operations =
+{
+	pid_fd_revalidate,	/* revalidate */
+	NULL,			/* d_hash */
+	NULL,			/* d_compare */
+	pid_delete_dentry	/* d_delete(struct dentry *) */
+};
+
+static struct dentry_operations pid_dentry_operations =
+{
+	NULL,			/* revalidate */
+	NULL,			/* d_hash */
+	NULL,			/* d_compare */
+	pid_delete_dentry	/* d_delete(struct dentry *) */
+};
+
+static struct dentry_operations pid_base_dentry_operations =
+{
+	pid_base_revalidate,	/* revalidate */
+	NULL,			/* d_hash */
+	NULL,			/* d_compare */
+	pid_delete_dentry	/* d_delete(struct dentry *) */
+};
+
+/* Lookups */
+
+static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry)
+{
+	unsigned int fd, c;
+	struct task_struct *task = dir->u.proc_i.task;
+	struct file * file;
+	struct files_struct * files;
+	struct inode *inode;
+	const char *name;
+	int len;
+
+	fd = 0;
+	len = dentry->d_name.len;
+	name = dentry->d_name.name;
+	if (len > 1 && *name == '0') goto out;
+	while (len-- > 0) {
+		c = *name - '0';
+		name++;
+		if (c > 9)
+			goto out;
+		fd *= 10;
+		fd += c;
+		if (fd & 0xffff8000)
+			goto out;
+	}
+
+	inode = proc_pid_make_inode(dir->i_sb, task, PROC_PID_FD_DIR+fd);
+	if (!inode)
+		goto out;
+	/* FIXME */
+	files = task->files;
+	if (!files)	/* can we ever get here if that's the case? */
+		goto out_unlock;
+	read_lock(&files->file_lock);
+	file = inode->u.proc_i.file = fcheck_task(task, fd);
+	if (!file)
+		goto out_unlock2;
+	get_file(file);
+	read_unlock(&files->file_lock);
+	inode->i_op = &proc_pid_link_inode_operations;
+	inode->i_size = 64;
+	inode->i_mode = S_IFLNK;
+	inode->u.proc_i.op.proc_get_link = proc_fd_link;
+	if (file->f_mode & 1)
+		inode->i_mode |= S_IRUSR | S_IXUSR;
+	if (file->f_mode & 2)
+		inode->i_mode |= S_IWUSR | S_IXUSR;
+	dentry->d_op = &pid_fd_dentry_operations;
+	d_add(dentry, inode);
+	return NULL;
+
+out_unlock2:
+	read_unlock(&files->file_lock);
+out_unlock:
+	iput(inode);
+out:
+	return ERR_PTR(-ENOENT);
+}
+
+static struct file_operations proc_fd_operations = {
+	NULL,			/* lseek - default */
+	proc_dir_read,		/* read - bad */
+	NULL,			/* write - bad */
+	proc_readfd,		/* readdir */
 };
-#endif
 
-void __init proc_base_init(void)
+/*
+ * proc directories can do almost nothing..
+ */
+static struct inode_operations proc_fd_inode_operations = {
+	&proc_fd_operations,	/* default base directory file-ops */
+	NULL,			/* create */
+	proc_lookupfd,		/* lookup */
+	NULL,			/* link */
+	NULL,			/* unlink */
+	NULL,			/* symlink */
+	NULL,			/* mkdir */
+	NULL,			/* rmdir */
+	NULL,			/* mknod */
+	NULL,			/* rename */
+	NULL,			/* readlink */
+	NULL,			/* follow_link */
+	NULL,			/* get_block */
+	NULL,			/* readpage */
+	NULL,			/* writepage */
+	NULL,			/* flushpage */
+	NULL,			/* truncate */
+	proc_permission,	/* permission */
+};
+
+static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry)
 {
+	struct inode *inode;
+	int error;
+	struct task_struct *task = dir->u.proc_i.task;
+	struct pid_entry *p;
+
+	error = -ENOENT;
+	inode = NULL;
+
+	for (p = base_stuff; p->name; p++) {
+		if (p->len != dentry->d_name.len)
+			continue;
+		if (!memcmp(dentry->d_name.name, p->name, p->len))
+			break;
+	}
+	if (!p->name)
+		goto out;
+
+	error = -EINVAL;
+	inode = proc_pid_make_inode(dir->i_sb, task, p->type);
+	if (!inode)
+		goto out;
+
+	inode->i_mode = p->mode;
+	/*
+	 * Yes, it does not scale. And it should not. Don't add
+	 * new entries into /proc/<pid>/ without very good reasons.
+	 */
+	switch(p->type) {
+		case PROC_PID_FD:
+			inode->i_nlink = 2;
+			inode->i_op = &proc_fd_inode_operations;
+			break;
+		case PROC_PID_EXE:
+			inode->i_op = &proc_pid_link_inode_operations;
+			inode->u.proc_i.op.proc_get_link = proc_exe_link;
+			break;
+		case PROC_PID_CWD:
+			inode->i_op = &proc_pid_link_inode_operations;
+			inode->u.proc_i.op.proc_get_link = proc_cwd_link;
+			break;
+		case PROC_PID_ROOT:
+			inode->i_op = &proc_pid_link_inode_operations;
+			inode->u.proc_i.op.proc_get_link = proc_root_link;
+			break;
+		case PROC_PID_ENVIRON:
+			inode->i_op = &proc_info_inode_operations;
+			inode->u.proc_i.op.proc_read = proc_pid_environ;
+			break;
+		case PROC_PID_STATUS:
+			inode->i_op = &proc_info_inode_operations;
+			inode->u.proc_i.op.proc_read = proc_pid_status;
+			break;
+		case PROC_PID_STAT:
+			inode->i_op = &proc_info_inode_operations;
+			inode->u.proc_i.op.proc_read = proc_pid_stat;
+			break;
+		case PROC_PID_CMDLINE:
+			inode->i_op = &proc_info_inode_operations;
+			inode->u.proc_i.op.proc_read = proc_pid_cmdline;
+			break;
+		case PROC_PID_STATM:
+			inode->i_op = &proc_info_inode_operations;
+			inode->u.proc_i.op.proc_read = proc_pid_statm;
+			break;
+		case PROC_PID_MAPS:
+			inode->i_op = &proc_maps_inode_operations;
+			break;
+#ifdef SMP
+		case PROC_PID_CPU:
+			inode->i_op = &proc_info_inode_operations;
+			inode->u.proc_i.op.proc_read = proc_pid_cpu;
+			break;
+#endif
 #if CONFIG_AP1000
-	proc_register(&proc_pid, &proc_pid_ringbuf);
+		case PROC_PID_RINGBUF:
+			inode->i_op = &proc_ringbuf_inode_operations;
+			break;
 #endif
-	proc_register(&proc_pid, &proc_pid_status);
-	proc_register(&proc_pid, &proc_pid_mem);
-	proc_register(&proc_pid, &proc_pid_cwd);
-	proc_register(&proc_pid, &proc_pid_root);
-	proc_register(&proc_pid, &proc_pid_exe);
-	proc_register(&proc_pid, &proc_pid_fd);
-	proc_register(&proc_pid, &proc_pid_environ);
-	proc_register(&proc_pid, &proc_pid_cmdline);
-	proc_register(&proc_pid, &proc_pid_stat);
-	proc_register(&proc_pid, &proc_pid_statm);
-	proc_register(&proc_pid, &proc_pid_maps);
-#ifdef __SMP__	
-	proc_register(&proc_pid, &proc_pid_cpu);
-#endif	
+		case PROC_PID_MEM:
+			inode->i_op = &proc_mem_inode_operations;
+			break;
+		default:
+			printk("procfs: impossible type (%d)",p->type);
+			iput(inode);
+			return ERR_PTR(-EINVAL);
+	}
+	dentry->d_op = &pid_dentry_operations;
+	d_add(dentry, inode);
+	return NULL;
+
+out:
+	return ERR_PTR(error);
+}
+
+static struct file_operations proc_base_operations = {
+	NULL,			/* lseek - default */
+	proc_dir_read,		/* read - bad */
+	NULL,			/* write - bad */
+	proc_base_readdir,	/* readdir */
 };
 
+static struct inode_operations proc_base_inode_operations = {
+	&proc_base_operations,	/* default base directory file-ops */
+	NULL,			/* create */
+	proc_base_lookup,	/* lookup */
+};
 
+struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry)
+{
+	unsigned int pid, c;
+	struct task_struct *task;
+	const char *name;
+	struct inode *inode;
+	int len;
+
+	pid = 0;
+	name = dentry->d_name.name;
+	len = dentry->d_name.len;
+	while (len-- > 0) {
+		c = *name - '0';
+		name++;
+		if (c > 9)
+			goto out;
+		pid *= 10;
+		pid += c;
+		if (!pid)
+			goto out;
+		if (pid & 0xffff0000)
+			goto out;
+	}
 
+	read_lock(&tasklist_lock);
+	task = find_task_by_pid(pid);
+	if (task)
+		atomic_inc(&mem_map[MAP_NR(task)].count);
+	read_unlock(&tasklist_lock);
+	if (!task)
+		goto out;
 
+	inode = proc_pid_make_inode(dir->i_sb, task, PROC_PID_INO);
 
+	free_task_struct(task);
 
+	if (!inode)
+		goto out;
+	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
+	inode->i_op = &proc_base_inode_operations;
+	inode->i_nlink = 3;
+	inode->i_flags|=S_IMMUTABLE;
+
+	dentry->d_op = &pid_base_dentry_operations;
+	d_add(dentry, inode);
+	return NULL;
+out:
+	return ERR_PTR(-ENOENT);
+}
 
+void proc_pid_delete_inode(struct inode *inode)
+{
+	if (inode->u.proc_i.file)
+		fput(inode->u.proc_i.file);
+	free_task_struct(inode->u.proc_i.task);
+}
 
+#define PROC_NUMBUF 10
+#define PROC_MAXPIDS 20
 
+/*
+ * Get a few pid's to return for filldir - we need to hold the
+ * tasklist lock while doing this, and we must release it before
+ * we actually do the filldir itself, so we use a temp buffer..
+ */
+static int get_pid_list(int index, unsigned int *pids)
+{
+	struct task_struct *p;
+	int nr_pids = 0;
 
+	index -= FIRST_PROCESS_ENTRY;
+	read_lock(&tasklist_lock);
+	for_each_task(p) {
+		int pid = p->pid;
+		if (!pid)
+			continue;
+		if (--index >= 0)
+			continue;
+		pids[nr_pids] = pid;
+		nr_pids++;
+		if (nr_pids >= PROC_MAXPIDS)
+			break;
+	}
+	read_unlock(&tasklist_lock);
+	return nr_pids;
+}
+
+int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
+{
+	unsigned int pid_array[PROC_MAXPIDS];
+	char buf[PROC_NUMBUF];
+	unsigned int nr = filp->f_pos;
+	unsigned int nr_pids, i;
+
+	nr_pids = get_pid_list(nr, pid_array);
+
+	for (i = 0; i < nr_pids; i++) {
+		int pid = pid_array[i];
+		ino_t ino = fake_ino(pid,PROC_PID_INO);
+		unsigned long j = PROC_NUMBUF;
+
+		do {
+			j--;
+			buf[j] = '0' + (pid % 10);
+			pid /= 10;
+		} while (pid);
+
+		if (filldir(dirent, buf+j, PROC_NUMBUF-j, filp->f_pos, ino) < 0)
+			break;
+		filp->f_pos++;
+	}
+	return 0;
+}