procfs: Move /proc/pid/fd[info] handling code to fd.[ch]

This patch prepares the ground for further extension of
/proc/pid/fd[info] handling code by moving fdinfo handling
code into fs/proc/fd.c.

I think such move makes both fs/proc/base.c and fs/proc/fd.c
easier to read.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
CC: Al Viro <viro@ZenIV.linux.org.uk>
CC: Alexey Dobriyan <adobriyan@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: James Bottomley <jbottomley@parallels.com>
CC: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
CC: Alexey Dobriyan <adobriyan@gmail.com>
CC: Matthew Helsley <matt.helsley@gmail.com>
CC: "J. Bruce Fields" <bfields@fieldses.org>
CC: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

5 files changed, 416 insertions, 387 deletions

diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index c1c729335924..99349efbbc2b 100644
--- a/fs/proc/Makefile
+++ b/fs/proc/Makefile
@@ -8,7 +8,7 @@ proc-y			:= nommu.o task_nommu.o
 proc-$(CONFIG_MMU)	:= mmu.o task_mmu.o
 
 proc-y       += inode.o root.o base.o generic.o array.o \
-		proc_tty.o
+		proc_tty.o fd.o
 proc-y	+= cmdline.o
 proc-y	+= consoles.o
 proc-y	+= cpuinfo.o
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 1b6c84cbdb73..b55c3bb298e3 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -90,6 +90,7 @@
 #endif
 #include <trace/events/oom.h>
 #include "internal.h"
+#include "fd.h"
 
 /* NOTE:
  *	Implementing inode permission operations in /proc is almost
@@ -136,8 +137,6 @@ struct pid_entry {
 		NULL, &proc_single_file_operations,	\
 		{ .proc_show = show } )
 
-static int proc_fd_permission(struct inode *inode, int mask);
-
 /*
  * Count the number of hardlinks for the pid_entry table, excluding the .
  * and .. links.
@@ -1492,7 +1491,7 @@ out:
 	return error;
 }
 
-static const struct inode_operations proc_pid_link_inode_operations = {
+const struct inode_operations proc_pid_link_inode_operations = {
 	.readlink	= proc_pid_readlink,
 	.follow_link	= proc_pid_follow_link,
 	.setattr	= proc_setattr,
@@ -1501,21 +1500,6 @@ static const struct inode_operations proc_pid_link_inode_operations = {
 
 /* building an inode */
 
-static int task_dumpable(struct task_struct *task)
-{
-	int dumpable = 0;
-	struct mm_struct *mm;
-
-	task_lock(task);
-	mm = task->mm;
-	if (mm)
-		dumpable = get_dumpable(mm);
-	task_unlock(task);
-	if(dumpable == 1)
-		return 1;
-	return 0;
-}
-
 struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task)
 {
 	struct inode * inode;
@@ -1641,15 +1625,6 @@ int pid_revalidate(struct dentry *dentry, unsigned int flags)
 	return 0;
 }
 
-static int pid_delete_dentry(const struct dentry * dentry)
-{
-	/* Is the task we represent dead?
-	 * If so, then don't put the dentry on the lru list,
-	 * kill it immediately.
-	 */
-	return !proc_pid(dentry->d_inode)->tasks[PIDTYPE_PID].first;
-}
-
 const struct dentry_operations pid_dentry_operations =
 {
 	.d_revalidate	= pid_revalidate,
@@ -1712,289 +1687,6 @@ end_instantiate:
 	return filldir(dirent, name, len, filp->f_pos, ino, type);
 }
 
-static unsigned name_to_int(struct dentry *dentry)
-{
-	const char *name = dentry->d_name.name;
-	int len = dentry->d_name.len;
-	unsigned n = 0;
-
-	if (len > 1 && *name == '0')
-		goto out;
-	while (len-- > 0) {
-		unsigned c = *name++ - '0';
-		if (c > 9)
-			goto out;
-		if (n >= (~0U-9)/10)
-			goto out;
-		n *= 10;
-		n += c;
-	}
-	return n;
-out:
-	return ~0U;
-}
-
-#define PROC_FDINFO_MAX 64
-
-static int proc_fd_info(struct inode *inode, struct path *path, char *info)
-{
-	struct task_struct *task = get_proc_task(inode);
-	struct files_struct *files = NULL;
-	struct file *file;
-	int fd = proc_fd(inode);
-
-	if (task) {
-		files = get_files_struct(task);
-		put_task_struct(task);
-	}
-	if (files) {
-		/*
-		 * We are not taking a ref to the file structure, so we must
-		 * hold ->file_lock.
-		 */
-		spin_lock(&files->file_lock);
-		file = fcheck_files(files, fd);
-		if (file) {
-			unsigned int f_flags;
-			struct fdtable *fdt;
-
-			fdt = files_fdtable(files);
-			f_flags = file->f_flags & ~O_CLOEXEC;
-			if (close_on_exec(fd, fdt))
-				f_flags |= O_CLOEXEC;
-
-			if (path) {
-				*path = file->f_path;
-				path_get(&file->f_path);
-			}
-			if (info)
-				snprintf(info, PROC_FDINFO_MAX,
-					 "pos:\t%lli\n"
-					 "flags:\t0%o\n",
-					 (long long) file->f_pos,
-					 f_flags);
-			spin_unlock(&files->file_lock);
-			put_files_struct(files);
-			return 0;
-		}
-		spin_unlock(&files->file_lock);
-		put_files_struct(files);
-	}
-	return -ENOENT;
-}
-
-static int proc_fd_link(struct dentry *dentry, struct path *path)
-{
-	return proc_fd_info(dentry->d_inode, path, NULL);
-}
-
-static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
-{
-	struct inode *inode;
-	struct task_struct *task;
-	int fd;
-	struct files_struct *files;
-	const struct cred *cred;
-
-	if (flags & LOOKUP_RCU)
-		return -ECHILD;
-
-	inode = dentry->d_inode;
-	task = get_proc_task(inode);
-	fd = proc_fd(inode);
-
-	if (task) {
-		files = get_files_struct(task);
-		if (files) {
-			struct file *file;
-			rcu_read_lock();
-			file = fcheck_files(files, fd);
-			if (file) {
-				unsigned f_mode = file->f_mode;
-
-				rcu_read_unlock();
-				put_files_struct(files);
-
-				if (task_dumpable(task)) {
-					rcu_read_lock();
-					cred = __task_cred(task);
-					inode->i_uid = cred->euid;
-					inode->i_gid = cred->egid;
-					rcu_read_unlock();
-				} else {
-					inode->i_uid = GLOBAL_ROOT_UID;
-					inode->i_gid = GLOBAL_ROOT_GID;
-				}
-
-				if (S_ISLNK(inode->i_mode)) {
-					unsigned i_mode = S_IFLNK;
-					if (f_mode & FMODE_READ)
-						i_mode |= S_IRUSR | S_IXUSR;
-					if (f_mode & FMODE_WRITE)
-						i_mode |= S_IWUSR | S_IXUSR;
-					inode->i_mode = i_mode;
-				}
-
-				security_task_to_inode(task, inode);
-				put_task_struct(task);
-				return 1;
-			}
-			rcu_read_unlock();
-			put_files_struct(files);
-		}
-		put_task_struct(task);
-	}
-	d_drop(dentry);
-	return 0;
-}
-
-static const struct dentry_operations tid_fd_dentry_operations =
-{
-	.d_revalidate	= tid_fd_revalidate,
-	.d_delete	= pid_delete_dentry,
-};
-
-static struct dentry *proc_fd_instantiate(struct inode *dir,
-	struct dentry *dentry, struct task_struct *task, const void *ptr)
-{
-	unsigned fd = (unsigned long)ptr;
- 	struct inode *inode;
- 	struct proc_inode *ei;
-	struct dentry *error = ERR_PTR(-ENOENT);
-
-	inode = proc_pid_make_inode(dir->i_sb, task);
-	if (!inode)
-		goto out;
-	ei = PROC_I(inode);
-	ei->fd = fd;
-
-	inode->i_mode = S_IFLNK;
-	inode->i_op = &proc_pid_link_inode_operations;
-	inode->i_size = 64;
-	ei->op.proc_get_link = proc_fd_link;
-	d_set_d_op(dentry, &tid_fd_dentry_operations);
-	d_add(dentry, inode);
-	/* Close the race of the process dying before we return the dentry */
-	if (tid_fd_revalidate(dentry, 0))
-		error = NULL;
-
- out:
-	return error;
-}
-
-static struct dentry *proc_lookupfd_common(struct inode *dir,
-					   struct dentry *dentry,
-					   instantiate_t instantiate)
-{
-	struct task_struct *task = get_proc_task(dir);
-	unsigned fd = name_to_int(dentry);
-	struct dentry *result = ERR_PTR(-ENOENT);
-
-	if (!task)
-		goto out_no_task;
-	if (fd == ~0U)
-		goto out;
-
-	result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);
-out:
-	put_task_struct(task);
-out_no_task:
-	return result;
-}
-
-static int proc_readfd_common(struct file * filp, void * dirent,
-			      filldir_t filldir, instantiate_t instantiate)
-{
-	struct dentry *dentry = filp->f_path.dentry;
-	struct inode *inode = dentry->d_inode;
-	struct task_struct *p = get_proc_task(inode);
-	unsigned int fd, ino;
-	int retval;
-	struct files_struct * files;
-
-	retval = -ENOENT;
-	if (!p)
-		goto out_no_task;
-	retval = 0;
-
-	fd = filp->f_pos;
-	switch (fd) {
-		case 0:
-			if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
-				goto out;
-			filp->f_pos++;
-		case 1:
-			ino = parent_ino(dentry);
-			if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
-				goto out;
-			filp->f_pos++;
-		default:
-			files = get_files_struct(p);
-			if (!files)
-				goto out;
-			rcu_read_lock();
-			for (fd = filp->f_pos-2;
-			     fd < files_fdtable(files)->max_fds;
-			     fd++, filp->f_pos++) {
-				char name[PROC_NUMBUF];
-				int len;
-				int rv;
-
-				if (!fcheck_files(files, fd))
-					continue;
-				rcu_read_unlock();
-
-				len = snprintf(name, sizeof(name), "%d", fd);
-				rv = proc_fill_cache(filp, dirent, filldir,
-						     name, len, instantiate, p,
-						     (void *)(unsigned long)fd);
-				if (rv < 0)
-					goto out_fd_loop;
-				rcu_read_lock();
-			}
-			rcu_read_unlock();
-out_fd_loop:
-			put_files_struct(files);
-	}
-out:
-	put_task_struct(p);
-out_no_task:
-	return retval;
-}
-
-static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
-				    unsigned int flags)
-{
-	return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
-}
-
-static int proc_readfd(struct file *filp, void *dirent, filldir_t filldir)
-{
-	return proc_readfd_common(filp, dirent, filldir, proc_fd_instantiate);
-}
-
-static ssize_t proc_fdinfo_read(struct file *file, char __user *buf,
-				      size_t len, loff_t *ppos)
-{
-	char tmp[PROC_FDINFO_MAX];
-	int err = proc_fd_info(file->f_path.dentry->d_inode, NULL, tmp);
-	if (!err)
-		err = simple_read_from_buffer(buf, len, ppos, tmp, strlen(tmp));
-	return err;
-}
-
-static const struct file_operations proc_fdinfo_file_operations = {
-	.open           = nonseekable_open,
-	.read		= proc_fdinfo_read,
-	.llseek		= no_llseek,
-};
-
-static const struct file_operations proc_fd_operations = {
-	.read		= generic_read_dir,
-	.readdir	= proc_readfd,
-	.llseek		= default_llseek,
-};
-
 #ifdef CONFIG_CHECKPOINT_RESTORE
 
 /*
@@ -2337,82 +2029,6 @@ static const struct file_operations proc_map_files_operations = {
 
 #endif /* CONFIG_CHECKPOINT_RESTORE */
 
-/*
- * /proc/pid/fd needs a special permission handler so that a process can still
- * access /proc/self/fd after it has executed a setuid().
- */
-static int proc_fd_permission(struct inode *inode, int mask)
-{
-	int rv = generic_permission(inode, mask);
-	if (rv == 0)
-		return 0;
-	if (task_pid(current) == proc_pid(inode))
-		rv = 0;
-	return rv;
-}
-
-/*
- * proc directories can do almost nothing..
- */
-static const struct inode_operations proc_fd_inode_operations = {
-	.lookup		= proc_lookupfd,
-	.permission	= proc_fd_permission,
-	.setattr	= proc_setattr,
-};
-
-static struct dentry *proc_fdinfo_instantiate(struct inode *dir,
-	struct dentry *dentry, struct task_struct *task, const void *ptr)
-{
-	unsigned fd = (unsigned long)ptr;
- 	struct inode *inode;
- 	struct proc_inode *ei;
-	struct dentry *error = ERR_PTR(-ENOENT);
-
-	inode = proc_pid_make_inode(dir->i_sb, task);
-	if (!inode)
-		goto out;
-	ei = PROC_I(inode);
-	ei->fd = fd;
-	inode->i_mode = S_IFREG | S_IRUSR;
-	inode->i_fop = &proc_fdinfo_file_operations;
-	d_set_d_op(dentry, &tid_fd_dentry_operations);
-	d_add(dentry, inode);
-	/* Close the race of the process dying before we return the dentry */
-	if (tid_fd_revalidate(dentry, 0))
-		error = NULL;
-
- out:
-	return error;
-}
-
-static struct dentry *proc_lookupfdinfo(struct inode *dir,
-					struct dentry *dentry,
-					unsigned int flags)
-{
-	return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
-}
-
-static int proc_readfdinfo(struct file *filp, void *dirent, filldir_t filldir)
-{
-	return proc_readfd_common(filp, dirent, filldir,
-				  proc_fdinfo_instantiate);
-}
-
-static const struct file_operations proc_fdinfo_operations = {
-	.read		= generic_read_dir,
-	.readdir	= proc_readfdinfo,
-	.llseek		= default_llseek,
-};
-
-/*
- * proc directories can do almost nothing..
- */
-static const struct inode_operations proc_fdinfo_inode_operations = {
-	.lookup		= proc_lookupfdinfo,
-	.setattr	= proc_setattr,
-};
-
-
 static struct dentry *proc_pident_instantiate(struct inode *dir,
 	struct dentry *dentry, struct task_struct *task, const void *ptr)
 {
diff --git a/fs/proc/fd.c b/fs/proc/fd.c
new file mode 100644
index 000000000000..1b0f932b4bd9
--- /dev/null
+++ b/fs/proc/fd.c
@@ -0,0 +1,351 @@
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/dcache.h>
+#include <linux/path.h>
+#include <linux/fdtable.h>
+#include <linux/namei.h>
+#include <linux/pid.h>
+#include <linux/security.h>
+
+#include <linux/proc_fs.h>
+
+#include "internal.h"
+#include "fd.h"
+
+#define PROC_FDINFO_MAX 64
+
+static int proc_fd_info(struct inode *inode, struct path *path, char *info)
+{
+	struct task_struct *task = get_proc_task(inode);
+	struct files_struct *files = NULL;
+	int fd = proc_fd(inode);
+	struct file *file;
+
+	if (task) {
+		files = get_files_struct(task);
+		put_task_struct(task);
+	}
+	if (files) {
+		/*
+		 * We are not taking a ref to the file structure, so we must
+		 * hold ->file_lock.
+		 */
+		spin_lock(&files->file_lock);
+		file = fcheck_files(files, fd);
+		if (file) {
+			unsigned int f_flags;
+			struct fdtable *fdt;
+
+			fdt = files_fdtable(files);
+			f_flags = file->f_flags & ~O_CLOEXEC;
+			if (close_on_exec(fd, fdt))
+				f_flags |= O_CLOEXEC;
+
+			if (path) {
+				*path = file->f_path;
+				path_get(&file->f_path);
+			}
+			if (info)
+				snprintf(info, PROC_FDINFO_MAX,
+					 "pos:\t%lli\n"
+					 "flags:\t0%o\n",
+					 (long long) file->f_pos,
+					 f_flags);
+			spin_unlock(&files->file_lock);
+			put_files_struct(files);
+			return 0;
+		}
+		spin_unlock(&files->file_lock);
+		put_files_struct(files);
+	}
+	return -ENOENT;
+}
+
+static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct files_struct *files;
+	struct task_struct *task;
+	const struct cred *cred;
+	struct inode *inode;
+	int fd;
+
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	inode = dentry->d_inode;
+	task = get_proc_task(inode);
+	fd = proc_fd(inode);
+
+	if (task) {
+		files = get_files_struct(task);
+		if (files) {
+			struct file *file;
+
+			rcu_read_lock();
+			file = fcheck_files(files, fd);
+			if (file) {
+				unsigned f_mode = file->f_mode;
+
+				rcu_read_unlock();
+				put_files_struct(files);
+
+				if (task_dumpable(task)) {
+					rcu_read_lock();
+					cred = __task_cred(task);
+					inode->i_uid = cred->euid;
+					inode->i_gid = cred->egid;
+					rcu_read_unlock();
+				} else {
+					inode->i_uid = GLOBAL_ROOT_UID;
+					inode->i_gid = GLOBAL_ROOT_GID;
+				}
+
+				if (S_ISLNK(inode->i_mode)) {
+					unsigned i_mode = S_IFLNK;
+					if (f_mode & FMODE_READ)
+						i_mode |= S_IRUSR | S_IXUSR;
+					if (f_mode & FMODE_WRITE)
+						i_mode |= S_IWUSR | S_IXUSR;
+					inode->i_mode = i_mode;
+				}
+
+				security_task_to_inode(task, inode);
+				put_task_struct(task);
+				return 1;
+			}
+			rcu_read_unlock();
+			put_files_struct(files);
+		}
+		put_task_struct(task);
+	}
+
+	d_drop(dentry);
+	return 0;
+}
+
+static const struct dentry_operations tid_fd_dentry_operations = {
+	.d_revalidate	= tid_fd_revalidate,
+	.d_delete	= pid_delete_dentry,
+};
+
+static int proc_fd_link(struct dentry *dentry, struct path *path)
+{
+	return proc_fd_info(dentry->d_inode, path, NULL);
+}
+
+static struct dentry *
+proc_fd_instantiate(struct inode *dir, struct dentry *dentry,
+		    struct task_struct *task, const void *ptr)
+{
+	struct dentry *error = ERR_PTR(-ENOENT);
+	unsigned fd = (unsigned long)ptr;
+	struct proc_inode *ei;
+	struct inode *inode;
+
+	inode = proc_pid_make_inode(dir->i_sb, task);
+	if (!inode)
+		goto out;
+
+	ei = PROC_I(inode);
+	ei->fd = fd;
+
+	inode->i_mode = S_IFLNK;
+	inode->i_op = &proc_pid_link_inode_operations;
+	inode->i_size = 64;
+
+	ei->op.proc_get_link = proc_fd_link;
+
+	d_set_d_op(dentry, &tid_fd_dentry_operations);
+	d_add(dentry, inode);
+
+	/* Close the race of the process dying before we return the dentry */
+	if (tid_fd_revalidate(dentry, 0))
+		error = NULL;
+ out:
+	return error;
+}
+
+static struct dentry *proc_lookupfd_common(struct inode *dir,
+					   struct dentry *dentry,
+					   instantiate_t instantiate)
+{
+	struct task_struct *task = get_proc_task(dir);
+	struct dentry *result = ERR_PTR(-ENOENT);
+	unsigned fd = name_to_int(dentry);
+
+	if (!task)
+		goto out_no_task;
+	if (fd == ~0U)
+		goto out;
+
+	result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);
+out:
+	put_task_struct(task);
+out_no_task:
+	return result;
+}
+
+static int proc_readfd_common(struct file * filp, void * dirent,
+			      filldir_t filldir, instantiate_t instantiate)
+{
+	struct dentry *dentry = filp->f_path.dentry;
+	struct inode *inode = dentry->d_inode;
+	struct task_struct *p = get_proc_task(inode);
+	struct files_struct *files;
+	unsigned int fd, ino;
+	int retval;
+
+	retval = -ENOENT;
+	if (!p)
+		goto out_no_task;
+	retval = 0;
+
+	fd = filp->f_pos;
+	switch (fd) {
+		case 0:
+			if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
+				goto out;
+			filp->f_pos++;
+		case 1:
+			ino = parent_ino(dentry);
+			if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
+				goto out;
+			filp->f_pos++;
+		default:
+			files = get_files_struct(p);
+			if (!files)
+				goto out;
+			rcu_read_lock();
+			for (fd = filp->f_pos - 2;
+			     fd < files_fdtable(files)->max_fds;
+			     fd++, filp->f_pos++) {
+				char name[PROC_NUMBUF];
+				int len;
+				int rv;
+
+				if (!fcheck_files(files, fd))
+					continue;
+				rcu_read_unlock();
+
+				len = snprintf(name, sizeof(name), "%d", fd);
+				rv = proc_fill_cache(filp, dirent, filldir,
+						     name, len, instantiate, p,
+						     (void *)(unsigned long)fd);
+				if (rv < 0)
+					goto out_fd_loop;
+				rcu_read_lock();
+			}
+			rcu_read_unlock();
+out_fd_loop:
+			put_files_struct(files);
+	}
+out:
+	put_task_struct(p);
+out_no_task:
+	return retval;
+}
+
+static ssize_t proc_fdinfo_read(struct file *file, char __user *buf,
+				size_t len, loff_t *ppos)
+{
+	char tmp[PROC_FDINFO_MAX];
+	int err = proc_fd_info(file->f_path.dentry->d_inode, NULL, tmp);
+	if (!err)
+		err = simple_read_from_buffer(buf, len, ppos, tmp, strlen(tmp));
+	return err;
+}
+
+static const struct file_operations proc_fdinfo_file_operations = {
+	.open           = nonseekable_open,
+	.read		= proc_fdinfo_read,
+	.llseek		= no_llseek,
+};
+
+static int proc_readfd(struct file *filp, void *dirent, filldir_t filldir)
+{
+	return proc_readfd_common(filp, dirent, filldir, proc_fd_instantiate);
+}
+
+const struct file_operations proc_fd_operations = {
+	.read		= generic_read_dir,
+	.readdir	= proc_readfd,
+	.llseek		= default_llseek,
+};
+
+static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
+				    unsigned int flags)
+{
+	return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
+}
+
+/*
+ * /proc/pid/fd needs a special permission handler so that a process can still
+ * access /proc/self/fd after it has executed a setuid().
+ */
+int proc_fd_permission(struct inode *inode, int mask)
+{
+	int rv = generic_permission(inode, mask);
+	if (rv == 0)
+		return 0;
+	if (task_pid(current) == proc_pid(inode))
+		rv = 0;
+	return rv;
+}
+
+const struct inode_operations proc_fd_inode_operations = {
+	.lookup		= proc_lookupfd,
+	.permission	= proc_fd_permission,
+	.setattr	= proc_setattr,
+};
+
+static struct dentry *
+proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry,
+			struct task_struct *task, const void *ptr)
+{
+	struct dentry *error = ERR_PTR(-ENOENT);
+	unsigned fd = (unsigned long)ptr;
+	struct proc_inode *ei;
+	struct inode *inode;
+
+	inode = proc_pid_make_inode(dir->i_sb, task);
+	if (!inode)
+		goto out;
+
+	ei = PROC_I(inode);
+	ei->fd = fd;
+
+	inode->i_mode = S_IFREG | S_IRUSR;
+	inode->i_fop = &proc_fdinfo_file_operations;
+
+	d_set_d_op(dentry, &tid_fd_dentry_operations);
+	d_add(dentry, inode);
+
+	/* Close the race of the process dying before we return the dentry */
+	if (tid_fd_revalidate(dentry, 0))
+		error = NULL;
+ out:
+	return error;
+}
+
+static struct dentry *
+proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
+{
+	return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
+}
+
+static int proc_readfdinfo(struct file *filp, void *dirent, filldir_t filldir)
+{
+	return proc_readfd_common(filp, dirent, filldir,
+				  proc_fdinfo_instantiate);
+}
+
+const struct inode_operations proc_fdinfo_inode_operations = {
+	.lookup		= proc_lookupfdinfo,
+	.setattr	= proc_setattr,
+};
+
+const struct file_operations proc_fdinfo_operations = {
+	.read		= generic_read_dir,
+	.readdir	= proc_readfdinfo,
+	.llseek		= default_llseek,
+};
diff --git a/fs/proc/fd.h b/fs/proc/fd.h
new file mode 100644
index 000000000000..cbb1d47deda8
--- /dev/null
+++ b/fs/proc/fd.h
@@ -0,0 +1,14 @@
+#ifndef __PROCFS_FD_H__
+#define __PROCFS_FD_H__
+
+#include <linux/fs.h>
+
+extern const struct file_operations proc_fd_operations;
+extern const struct inode_operations proc_fd_inode_operations;
+
+extern const struct file_operations proc_fdinfo_operations;
+extern const struct inode_operations proc_fdinfo_inode_operations;
+
+extern int proc_fd_permission(struct inode *inode, int mask);
+
+#endif /* __PROCFS_FD_H__ */
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index e1167a1c9126..67925a7bd8cb 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -9,6 +9,7 @@
  * 2 of the License, or (at your option) any later version.
  */
 
+#include <linux/sched.h>
 #include <linux/proc_fs.h>
 struct  ctl_table_header;
 
@@ -65,6 +66,7 @@ extern const struct file_operations proc_clear_refs_operations;
 extern const struct file_operations proc_pagemap_operations;
 extern const struct file_operations proc_net_operations;
 extern const struct inode_operations proc_net_inode_operations;
+extern const struct inode_operations proc_pid_link_inode_operations;
 
 struct proc_maps_private {
 	struct pid *pid;
@@ -91,6 +93,52 @@ static inline int proc_fd(struct inode *inode)
 	return PROC_I(inode)->fd;
 }
 
+static inline int task_dumpable(struct task_struct *task)
+{
+	int dumpable = 0;
+	struct mm_struct *mm;
+
+	task_lock(task);
+	mm = task->mm;
+	if (mm)
+		dumpable = get_dumpable(mm);
+	task_unlock(task);
+	if(dumpable == 1)
+		return 1;
+	return 0;
+}
+
+static inline int pid_delete_dentry(const struct dentry * dentry)
+{
+	/* Is the task we represent dead?
+	 * If so, then don't put the dentry on the lru list,
+	 * kill it immediately.
+	 */
+	return !proc_pid(dentry->d_inode)->tasks[PIDTYPE_PID].first;
+}
+
+static inline unsigned name_to_int(struct dentry *dentry)
+{
+	const char *name = dentry->d_name.name;
+	int len = dentry->d_name.len;
+	unsigned n = 0;
+
+	if (len > 1 && *name == '0')
+		goto out;
+	while (len-- > 0) {
+		unsigned c = *name++ - '0';
+		if (c > 9)
+			goto out;
+		if (n >= (~0U-9)/10)
+			goto out;
+		n *= 10;
+		n += c;
+	}
+	return n;
+out:
+	return ~0U;
+}
+
 struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *ino,
 		struct dentry *dentry);
 int proc_readdir_de(struct proc_dir_entry *de, struct file *filp, void *dirent,