5 files changed, 915 insertions, 12 deletions

diff --git a/fs/autofs4/Makefile b/fs/autofs4/Makefile
index f2c3b79e94d2..a811c1f7d9ab 100644
--- a/fs/autofs4/Makefile
+++ b/fs/autofs4/Makefile
@@ -4,4 +4,4 @@
 
 obj-$(CONFIG_AUTOFS4_FS) += autofs4.o
 
-autofs4-objs := init.o inode.o root.o symlink.o waitq.o expire.o
+autofs4-objs := init.o inode.o root.o symlink.o waitq.o expire.o dev-ioctl.o
diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index fa76d18be082..e0f16da00e54 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -14,6 +14,7 @@
 /* Internal header file for autofs */
 
 #include <linux/auto_fs4.h>
+#include <linux/auto_dev-ioctl.h>
 #include <linux/mutex.h>
 #include <linux/list.h>
 
@@ -21,6 +22,9 @@
 #define AUTOFS_IOC_FIRST     AUTOFS_IOC_READY
 #define AUTOFS_IOC_COUNT     32
 
+#define AUTOFS_DEV_IOCTL_IOC_FIRST      (AUTOFS_DEV_IOCTL_VERSION)
+#define AUTOFS_DEV_IOCTL_IOC_COUNT      (AUTOFS_IOC_COUNT - 11)
+
 #define AUTOFS_TYPE_TRIGGER     (AUTOFS_TYPE_DIRECT|AUTOFS_TYPE_OFFSET)
 
 #include <linux/kernel.h>
@@ -37,11 +41,27 @@
 /* #define DEBUG */
 
 #ifdef DEBUG
-#define DPRINTK(fmt,args...) do { printk(KERN_DEBUG "pid %d: %s: " fmt "\n" , current->pid , __func__ , ##args); } while(0)
+#define DPRINTK(fmt, args...)                           \
+do {                                                    \
+        printk(KERN_DEBUG "pid %d: %s: " fmt "\n",      \
+                current->pid, __func__, ##args);        \
+} while (0)
 #else
-#define DPRINTK(fmt,args...) do {} while(0)
+#define DPRINTK(fmt, args...) do {} while (0)
 #endif
 
+#define AUTOFS_WARN(fmt, args...)                       \
+do {                                                    \
+        printk(KERN_WARNING "pid %d: %s: " fmt "\n",    \
+                current->pid, __func__, ##args);        \
+} while (0)
+
+#define AUTOFS_ERROR(fmt, args...)                      \
+do {                                                    \
+        printk(KERN_ERR "pid %d: %s: " fmt "\n",        \
+                current->pid, __func__, ##args);        \
+} while (0)
+
 /* Unified info structure.  This is pointed to by both the dentry and
    inode structures.  Each file in the filesystem has an instance of this
    structure.  It holds a reference to the dentry, so dentries are never
@@ -170,6 +190,17 @@ int autofs4_expire_run(struct super_block *, struct vfsmount *,
                         struct autofs_packet_expire __user *);
 int autofs4_expire_multi(struct super_block *, struct vfsmount *,
                         struct autofs_sb_info *, int __user *);
+struct dentry *autofs4_expire_direct(struct super_block *sb,
+                                     struct vfsmount *mnt,
+                                     struct autofs_sb_info *sbi, int how);
+struct dentry *autofs4_expire_indirect(struct super_block *sb,
+                                       struct vfsmount *mnt,
+                                       struct autofs_sb_info *sbi, int how);
+
+/* Device node initialization */
+
+int autofs_dev_ioctl_init(void);
+void autofs_dev_ioctl_exit(void);
 
 /* Operations structures */
 
diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
new file mode 100644
index 000000000000..625abf5422e2
--- /dev/null
+++ b/fs/autofs4/dev-ioctl.c
@@ -0,0 +1,863 @@
+/*
+ * Copyright 2008 Red Hat, Inc. All rights reserved.
+ * Copyright 2008 Ian Kent <raven@themaw.net>
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ */
+
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/miscdevice.h>
+#include <linux/init.h>
+#include <linux/wait.h>
+#include <linux/namei.h>
+#include <linux/fcntl.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/sched.h>
+#include <linux/compat.h>
+#include <linux/syscalls.h>
+#include <linux/smp_lock.h>
+#include <linux/magic.h>
+#include <linux/dcache.h>
+#include <linux/uaccess.h>
+
+#include "autofs_i.h"
+
+/*
+ * This module implements an interface for routing autofs ioctl control
+ * commands via a miscellaneous device file.
+ *
+ * The alternate interface is needed because we need to be able open
+ * an ioctl file descriptor on an autofs mount that may be covered by
+ * another mount. This situation arises when starting automount(8)
+ * or other user space daemon which uses direct mounts or offset
+ * mounts (used for autofs lazy mount/umount of nested mount trees),
+ * which have been left busy at at service shutdown.
+ */
+
+#define AUTOFS_DEV_IOCTL_SIZE   sizeof(struct autofs_dev_ioctl)
+
+typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
+                        struct autofs_dev_ioctl *);
+
+static int check_name(const char *name)
+{
+        if (!strchr(name, '/'))
+                return -EINVAL;
+        return 0;
+}
+
+/*
+ * Check a string doesn't overrun the chunk of
+ * memory we copied from user land.
+ */
+static int invalid_str(char *str, void *end)
+{
+        while ((void *) str <= end)
+                if (!*str++)
+                        return 0;
+        return -EINVAL;
+}
+
+/*
+ * Check that the user compiled against correct version of autofs
+ * misc device code.
+ *
+ * As well as checking the version compatibility this always copies
+ * the kernel interface version out.
+ */
+static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
+{
+        int err = 0;
+
+        if ((AUTOFS_DEV_IOCTL_VERSION_MAJOR != param->ver_major) ||
+            (AUTOFS_DEV_IOCTL_VERSION_MINOR < param->ver_minor)) {
+                AUTOFS_WARN("ioctl control interface version mismatch: "
+                     "kernel(%u.%u), user(%u.%u), cmd(%d)",
+                     AUTOFS_DEV_IOCTL_VERSION_MAJOR,
+                     AUTOFS_DEV_IOCTL_VERSION_MINOR,
+                     param->ver_major, param->ver_minor, cmd);
+                err = -EINVAL;
+        }
+
+        /* Fill in the kernel version. */
+        param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
+        param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
+
+        return err;
+}
+
+/*
+ * Copy parameter control struct, including a possible path allocated
+ * at the end of the struct.
+ */
+static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
+{
+        struct autofs_dev_ioctl tmp, *ads;
+
+        if (copy_from_user(&tmp, in, sizeof(tmp)))
+                return ERR_PTR(-EFAULT);
+
+        if (tmp.size < sizeof(tmp))
+                return ERR_PTR(-EINVAL);
+
+        ads = kmalloc(tmp.size, GFP_KERNEL);
+        if (!ads)
+                return ERR_PTR(-ENOMEM);
+
+        if (copy_from_user(ads, in, tmp.size)) {
+                kfree(ads);
+                return ERR_PTR(-EFAULT);
+        }
+
+        return ads;
+}
+
+static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
+{
+        kfree(param);
+        return;
+}
+
+/*
+ * Check sanity of parameter control fields and if a path is present
+ * check that it has a "/" and is terminated.
+ */
+static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
+{
+        int err = -EINVAL;
+
+        if (check_dev_ioctl_version(cmd, param)) {
+                AUTOFS_WARN("invalid device control module version "
+                     "supplied for cmd(0x%08x)", cmd);
+                goto out;
+        }
+
+        if (param->size > sizeof(*param)) {
+                err = check_name(param->path);
+                if (err) {
+                        AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
+                                    cmd);
+                        goto out;
+                }
+
+                err = invalid_str(param->path,
+                                 (void *) ((size_t) param + param->size));
+                if (err) {
+                        AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
+                                    cmd);
+                        goto out;
+                }
+        }
+
+        err = 0;
+out:
+        return err;
+}
+
+/*
+ * Get the autofs super block info struct from the file opened on
+ * the autofs mount point.
+ */
+static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
+{
+        struct autofs_sb_info *sbi = NULL;
+        struct inode *inode;
+
+        if (f) {
+                inode = f->f_path.dentry->d_inode;
+                sbi = autofs4_sbi(inode->i_sb);
+        }
+        return sbi;
+}
+
+/* Return autofs module protocol version */
+static int autofs_dev_ioctl_protover(struct file *fp,
+                                     struct autofs_sb_info *sbi,
+                                     struct autofs_dev_ioctl *param)
+{
+        param->arg1 = sbi->version;
+        return 0;
+}
+
+/* Return autofs module protocol sub version */
+static int autofs_dev_ioctl_protosubver(struct file *fp,
+                                        struct autofs_sb_info *sbi,
+                                        struct autofs_dev_ioctl *param)
+{
+        param->arg1 = sbi->sub_version;
+        return 0;
+}
+
+/*
+ * Walk down the mount stack looking for an autofs mount that
+ * has the requested device number (aka. new_encode_dev(sb->s_dev).
+ */
+static int autofs_dev_ioctl_find_super(struct nameidata *nd, dev_t devno)
+{
+        struct dentry *dentry;
+        struct inode *inode;
+        struct super_block *sb;
+        dev_t s_dev;
+        unsigned int err;
+
+        err = -ENOENT;
+
+        /* Lookup the dentry name at the base of our mount point */
+        dentry = d_lookup(nd->path.dentry, &nd->last);
+        if (!dentry)
+                goto out;
+
+        dput(nd->path.dentry);
+        nd->path.dentry = dentry;
+
+        /* And follow the mount stack looking for our autofs mount */
+        while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
+                inode = nd->path.dentry->d_inode;
+                if (!inode)
+                        break;
+
+                sb = inode->i_sb;
+                s_dev = new_encode_dev(sb->s_dev);
+                if (devno == s_dev) {
+                        if (sb->s_magic == AUTOFS_SUPER_MAGIC) {
+                                err = 0;
+                                break;
+                        }
+                }
+        }
+out:
+        return err;
+}
+
+/*
+ * Walk down the mount stack looking for an autofs mount that
+ * has the requested mount type (ie. indirect, direct or offset).
+ */
+static int autofs_dev_ioctl_find_sbi_type(struct nameidata *nd, unsigned int type)
+{
+        struct dentry *dentry;
+        struct autofs_info *ino;
+        unsigned int err;
+
+        err = -ENOENT;
+
+        /* Lookup the dentry name at the base of our mount point */
+        dentry = d_lookup(nd->path.dentry, &nd->last);
+        if (!dentry)
+                goto out;
+
+        dput(nd->path.dentry);
+        nd->path.dentry = dentry;
+
+        /* And follow the mount stack looking for our autofs mount */
+        while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
+                ino = autofs4_dentry_ino(nd->path.dentry);
+                if (ino && ino->sbi->type & type) {
+                        err = 0;
+                        break;
+                }
+        }
+out:
+        return err;
+}
+
+static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
+{
+        struct files_struct *files = current->files;
+        struct fdtable *fdt;
+
+        spin_lock(&files->file_lock);
+        fdt = files_fdtable(files);
+        BUG_ON(fdt->fd[fd] != NULL);
+        rcu_assign_pointer(fdt->fd[fd], file);
+        FD_SET(fd, fdt->close_on_exec);
+        spin_unlock(&files->file_lock);
+}
+
+
+/*
+ * Open a file descriptor on the autofs mount point corresponding
+ * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
+ */
+static int autofs_dev_ioctl_open_mountpoint(const char *path, dev_t devid)
+{
+        struct file *filp;
+        struct nameidata nd;
+        int err, fd;
+
+        fd = get_unused_fd();
+        if (likely(fd >= 0)) {
+                /* Get nameidata of the parent directory */
+                err = path_lookup(path, LOOKUP_PARENT, &nd);
+                if (err)
+                        goto out;
+
+                /*
+                 * Search down, within the parent, looking for an
+                 * autofs super block that has the device number
+                 * corresponding to the autofs fs we want to open.
+                 */
+                err = autofs_dev_ioctl_find_super(&nd, devid);
+                if (err) {
+                        path_put(&nd.path);
+                        goto out;
+                }
+
+                filp = dentry_open(nd.path.dentry, nd.path.mnt, O_RDONLY);
+                if (IS_ERR(filp)) {
+                        err = PTR_ERR(filp);
+                        goto out;
+                }
+
+                autofs_dev_ioctl_fd_install(fd, filp);
+        }
+
+        return fd;
+
+out:
+        put_unused_fd(fd);
+        return err;
+}
+
+/* Open a file descriptor on an autofs mount point */
+static int autofs_dev_ioctl_openmount(struct file *fp,
+                                      struct autofs_sb_info *sbi,
+                                      struct autofs_dev_ioctl *param)
+{
+        const char *path;
+        dev_t devid;
+        int err, fd;
+
+        /* param->path has already been checked */
+        if (!param->arg1)
+                return -EINVAL;
+
+        param->ioctlfd = -1;
+
+        path = param->path;
+        devid = param->arg1;
+
+        err = 0;
+        fd = autofs_dev_ioctl_open_mountpoint(path, devid);
+        if (unlikely(fd < 0)) {
+                err = fd;
+                goto out;
+        }
+
+        param->ioctlfd = fd;
+out:
+        return err;
+}
+
+/* Close file descriptor allocated above (user can also use close(2)). */
+static int autofs_dev_ioctl_closemount(struct file *fp,
+                                       struct autofs_sb_info *sbi,
+                                       struct autofs_dev_ioctl *param)
+{
+        return sys_close(param->ioctlfd);
+}
+
+/*
+ * Send "ready" status for an existing wait (either a mount or an expire
+ * request).
+ */
+static int autofs_dev_ioctl_ready(struct file *fp,
+                                  struct autofs_sb_info *sbi,
+                                  struct autofs_dev_ioctl *param)
+{
+        autofs_wqt_t token;
+
+        token = (autofs_wqt_t) param->arg1;
+        return autofs4_wait_release(sbi, token, 0);
+}
+
+/*
+ * Send "fail" status for an existing wait (either a mount or an expire
+ * request).
+ */
+static int autofs_dev_ioctl_fail(struct file *fp,
+                                 struct autofs_sb_info *sbi,
+                                 struct autofs_dev_ioctl *param)
+{
+        autofs_wqt_t token;
+        int status;
+
+        token = (autofs_wqt_t) param->arg1;
+        status = param->arg2 ? param->arg2 : -ENOENT;
+        return autofs4_wait_release(sbi, token, status);
+}
+
+/*
+ * Set the pipe fd for kernel communication to the daemon.
+ *
+ * Normally this is set at mount using an option but if we
+ * are reconnecting to a busy mount then we need to use this
+ * to tell the autofs mount about the new kernel pipe fd. In
+ * order to protect mounts against incorrectly setting the
+ * pipefd we also require that the autofs mount be catatonic.
+ *
+ * This also sets the process group id used to identify the
+ * controlling process (eg. the owning automount(8) daemon).
+ */
+static int autofs_dev_ioctl_setpipefd(struct file *fp,
+                                      struct autofs_sb_info *sbi,
+                                      struct autofs_dev_ioctl *param)
+{
+        int pipefd;
+        int err = 0;
+
+        if (param->arg1 == -1)
+                return -EINVAL;
+
+        pipefd = param->arg1;
+
+        mutex_lock(&sbi->wq_mutex);
+        if (!sbi->catatonic) {
+                mutex_unlock(&sbi->wq_mutex);
+                return -EBUSY;
+        } else {
+                struct file *pipe = fget(pipefd);
+                if (!pipe->f_op || !pipe->f_op->write) {
+                        err = -EPIPE;
+                        fput(pipe);
+                        goto out;
+                }
+                sbi->oz_pgrp = task_pgrp_nr(current);
+                sbi->pipefd = pipefd;
+                sbi->pipe = pipe;
+                sbi->catatonic = 0;
+        }
+out:
+        mutex_unlock(&sbi->wq_mutex);
+        return err;
+}
+
+/*
+ * Make the autofs mount point catatonic, no longer responsive to
+ * mount requests. Also closes the kernel pipe file descriptor.
+ */
+static int autofs_dev_ioctl_catatonic(struct file *fp,
+                                      struct autofs_sb_info *sbi,
+                                      struct autofs_dev_ioctl *param)
+{
+        autofs4_catatonic_mode(sbi);
+        return 0;
+}
+
+/* Set the autofs mount timeout */
+static int autofs_dev_ioctl_timeout(struct file *fp,
+                                    struct autofs_sb_info *sbi,
+                                    struct autofs_dev_ioctl *param)
+{
+        unsigned long timeout;
+
+        timeout = param->arg1;
+        param->arg1 = sbi->exp_timeout / HZ;
+        sbi->exp_timeout = timeout * HZ;
+        return 0;
+}
+
+/*
+ * Return the uid and gid of the last request for the mount
+ *
+ * When reconstructing an autofs mount tree with active mounts
+ * we need to re-connect to mounts that may have used the original
+ * process uid and gid (or string variations of them) for mount
+ * lookups within the map entry.
+ */
+static int autofs_dev_ioctl_requester(struct file *fp,
+                                      struct autofs_sb_info *sbi,
+                                      struct autofs_dev_ioctl *param)
+{
+        struct autofs_info *ino;
+        struct nameidata nd;
+        const char *path;
+        dev_t devid;
+        int err = -ENOENT;
+
+        if (param->size <= sizeof(*param)) {
+                err = -EINVAL;
+                goto out;
+        }
+
+        path = param->path;
+        devid = sbi->sb->s_dev;
+
+        param->arg1 = param->arg2 = -1;
+
+        /* Get nameidata of the parent directory */
+        err = path_lookup(path, LOOKUP_PARENT, &nd);
+        if (err)
+                goto out;
+
+        err = autofs_dev_ioctl_find_super(&nd, devid);
+        if (err)
+                goto out_release;
+
+        ino = autofs4_dentry_ino(nd.path.dentry);
+        if (ino) {
+                err = 0;
+                autofs4_expire_wait(nd.path.dentry);
+                spin_lock(&sbi->fs_lock);
+                param->arg1 = ino->uid;
+                param->arg2 = ino->gid;
+                spin_unlock(&sbi->fs_lock);
+        }
+
+out_release:
+        path_put(&nd.path);
+out:
+        return err;
+}
+
+/*
+ * Call repeatedly until it returns -EAGAIN, meaning there's nothing
+ * more that can be done.
+ */
+static int autofs_dev_ioctl_expire(struct file *fp,
+                                   struct autofs_sb_info *sbi,
+                                   struct autofs_dev_ioctl *param)
+{
+        struct dentry *dentry;
+        struct vfsmount *mnt;
+        int err = -EAGAIN;
+        int how;
+
+        how = param->arg1;
+        mnt = fp->f_path.mnt;
+
+        if (sbi->type & AUTOFS_TYPE_TRIGGER)
+                dentry = autofs4_expire_direct(sbi->sb, mnt, sbi, how);
+        else
+                dentry = autofs4_expire_indirect(sbi->sb, mnt, sbi, how);
+
+        if (dentry) {
+                struct autofs_info *ino = autofs4_dentry_ino(dentry);
+
+                /*
+                 * This is synchronous because it makes the daemon a
+                 * little easier
+                */
+                err = autofs4_wait(sbi, dentry, NFY_EXPIRE);
+
+                spin_lock(&sbi->fs_lock);
+                if (ino->flags & AUTOFS_INF_MOUNTPOINT) {
+                        ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
+                        sbi->sb->s_root->d_mounted++;
+                }
+                ino->flags &= ~AUTOFS_INF_EXPIRING;
+                complete_all(&ino->expire_complete);
+                spin_unlock(&sbi->fs_lock);
+                dput(dentry);
+        }
+
+        return err;
+}
+
+/* Check if autofs mount point is in use */
+static int autofs_dev_ioctl_askumount(struct file *fp,
+                                      struct autofs_sb_info *sbi,
+                                      struct autofs_dev_ioctl *param)
+{
+        param->arg1 = 0;
+        if (may_umount(fp->f_path.mnt))
+                param->arg1 = 1;
+        return 0;
+}
+
+/*
+ * Check if the given path is a mountpoint.
+ *
+ * If we are supplied with the file descriptor of an autofs
+ * mount we're looking for a specific mount. In this case
+ * the path is considered a mountpoint if it is itself a
+ * mountpoint or contains a mount, such as a multi-mount
+ * without a root mount. In this case we return 1 if the
+ * path is a mount point and the super magic of the covering
+ * mount if there is one or 0 if it isn't a mountpoint.
+ *
+ * If we aren't supplied with a file descriptor then we
+ * lookup the nameidata of the path and check if it is the
+ * root of a mount. If a type is given we are looking for
+ * a particular autofs mount and if we don't find a match
+ * we return fail. If the located nameidata path is the
+ * root of a mount we return 1 along with the super magic
+ * of the mount or 0 otherwise.
+ *
+ * In both cases the the device number (as returned by
+ * new_encode_dev()) is also returned.
+ */
+static int autofs_dev_ioctl_ismountpoint(struct file *fp,
+                                         struct autofs_sb_info *sbi,
+                                         struct autofs_dev_ioctl *param)
+{
+        struct nameidata nd;
+        const char *path;
+        unsigned int type;
+        int err = -ENOENT;
+
+        if (param->size <= sizeof(*param)) {
+                err = -EINVAL;
+                goto out;
+        }
+
+        path = param->path;
+        type = param->arg1;
+
+        param->arg1 = 0;
+        param->arg2 = 0;
+
+        if (!fp || param->ioctlfd == -1) {
+                if (type == AUTOFS_TYPE_ANY) {
+                        struct super_block *sb;
+
+                        err = path_lookup(path, LOOKUP_FOLLOW, &nd);
+                        if (err)
+                                goto out;
+
+                        sb = nd.path.dentry->d_sb;
+                        param->arg1 = new_encode_dev(sb->s_dev);
+                } else {
+                        struct autofs_info *ino;
+
+                        err = path_lookup(path, LOOKUP_PARENT, &nd);
+                        if (err)
+                                goto out;
+
+                        err = autofs_dev_ioctl_find_sbi_type(&nd, type);
+                        if (err)
+                                goto out_release;
+
+                        ino = autofs4_dentry_ino(nd.path.dentry);
+                        param->arg1 = autofs4_get_dev(ino->sbi);
+                }
+
+                err = 0;
+                if (nd.path.dentry->d_inode &&
+                    nd.path.mnt->mnt_root == nd.path.dentry) {
+                        err = 1;
+                        param->arg2 = nd.path.dentry->d_inode->i_sb->s_magic;
+                }
+        } else {
+                dev_t devid = new_encode_dev(sbi->sb->s_dev);
+
+                err = path_lookup(path, LOOKUP_PARENT, &nd);
+                if (err)
+                        goto out;
+
+                err = autofs_dev_ioctl_find_super(&nd, devid);
+                if (err)
+                        goto out_release;
+
+                param->arg1 = autofs4_get_dev(sbi);
+
+                err = have_submounts(nd.path.dentry);
+
+                if (nd.path.mnt->mnt_mountpoint != nd.path.mnt->mnt_root) {
+                        if (follow_down(&nd.path.mnt, &nd.path.dentry)) {
+                                struct inode *inode = nd.path.dentry->d_inode;
+                                param->arg2 = inode->i_sb->s_magic;
+                        }
+                }
+        }
+
+out_release:
+        path_put(&nd.path);
+out:
+        return err;
+}
+
+/*
+ * Our range of ioctl numbers isn't 0 based so we need to shift
+ * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
+ * lookup.
+ */
+#define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
+
+static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
+{
+        static struct {
+                int cmd;
+                ioctl_fn fn;
+        } _ioctls[] = {
+                {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
+                {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
+                         autofs_dev_ioctl_protover},
+                {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
+                         autofs_dev_ioctl_protosubver},
+                {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
+                         autofs_dev_ioctl_openmount},
+                {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
+                         autofs_dev_ioctl_closemount},
+                {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
+                         autofs_dev_ioctl_ready},
+                {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
+                         autofs_dev_ioctl_fail},
+                {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
+                         autofs_dev_ioctl_setpipefd},
+                {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
+                         autofs_dev_ioctl_catatonic},
+                {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
+                         autofs_dev_ioctl_timeout},
+                {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
+                         autofs_dev_ioctl_requester},
+                {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
+                         autofs_dev_ioctl_expire},
+                {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
+                         autofs_dev_ioctl_askumount},
+                {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
+                         autofs_dev_ioctl_ismountpoint}
+        };
+        unsigned int idx = cmd_idx(cmd);
+
+        return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
+}
+
+/* ioctl dispatcher */
+static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
+{
+        struct autofs_dev_ioctl *param;
+        struct file *fp;
+        struct autofs_sb_info *sbi;
+        unsigned int cmd_first, cmd;
+        ioctl_fn fn = NULL;
+        int err = 0;
+
+        /* only root can play with this */
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
+        cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
+        cmd = _IOC_NR(command);
+
+        if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
+            cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
+                return -ENOTTY;
+        }
+
+        /* Copy the parameters into kernel space. */
+        param = copy_dev_ioctl(user);
+        if (IS_ERR(param))
+                return PTR_ERR(param);
+
+        err = validate_dev_ioctl(command, param);
+        if (err)
+                goto out;
+
+        /* The validate routine above always sets the version */
+        if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
+                goto done;
+
+        fn = lookup_dev_ioctl(cmd);
+        if (!fn) {
+                AUTOFS_WARN("unknown command 0x%08x", command);
+                return -ENOTTY;
+        }
+
+        fp = NULL;
+        sbi = NULL;
+
+        /*
+         * For obvious reasons the openmount can't have a file
+         * descriptor yet. We don't take a reference to the
+         * file during close to allow for immediate release.
+         */
+        if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
+            cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
+                fp = fget(param->ioctlfd);
+                if (!fp) {
+                        if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
+                                goto cont;
+                        err = -EBADF;
+                        goto out;
+                }
+
+                if (!fp->f_op) {
+                        err = -ENOTTY;
+                        fput(fp);
+                        goto out;
+                }
+
+                sbi = autofs_dev_ioctl_sbi(fp);
+                if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
+                        err = -EINVAL;
+                        fput(fp);
+                        goto out;
+                }
+
+                /*
+                 * Admin needs to be able to set the mount catatonic in
+                 * order to be able to perform the re-open.
+                 */
+                if (!autofs4_oz_mode(sbi) &&
+                    cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
+                        err = -EACCES;
+                        fput(fp);
+                        goto out;
+                }
+        }
+cont:
+        err = fn(fp, sbi, param);
+
+        if (fp)
+                fput(fp);
+done:
+        if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
+                err = -EFAULT;
+out:
+        free_dev_ioctl(param);
+        return err;
+}
+
+static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
+{
+        int err;
+        err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
+        return (long) err;
+}
+
+#ifdef CONFIG_COMPAT
+static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
+{
+        return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
+}
+#else
+#define autofs_dev_ioctl_compat NULL
+#endif
+
+static const struct file_operations _dev_ioctl_fops = {
+        .unlocked_ioctl  = autofs_dev_ioctl,
+        .compat_ioctl = autofs_dev_ioctl_compat,
+        .owner   = THIS_MODULE,
+};
+
+static struct miscdevice _autofs_dev_ioctl_misc = {
+        .minor          = MISC_DYNAMIC_MINOR,
+        .name           = AUTOFS_DEVICE_NAME,
+        .fops           = &_dev_ioctl_fops
+};
+
+/* Register/deregister misc character device */
+int autofs_dev_ioctl_init(void)
+{
+        int r;
+
+        r = misc_register(&_autofs_dev_ioctl_misc);
+        if (r) {
+                AUTOFS_ERROR("misc_register failed for control device");
+                return r;
+        }
+
+        return 0;
+}
+
+void autofs_dev_ioctl_exit(void)
+{
+        misc_deregister(&_autofs_dev_ioctl_misc);
+        return;
+}
+
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index e79dd09e12a1..cde2f8e8935a 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -244,10 +244,10 @@ cont:
 }
 
 /* Check if we can expire a direct mount (possibly a tree) */
-static struct dentry *autofs4_expire_direct(struct super_block *sb,
-                                            struct vfsmount *mnt,
-                                            struct autofs_sb_info *sbi,
-                                            int how)
+struct dentry *autofs4_expire_direct(struct super_block *sb,
+                                     struct vfsmount *mnt,
+                                     struct autofs_sb_info *sbi,
+                                     int how)
 {
         unsigned long timeout;
         struct dentry *root = dget(sb->s_root);
@@ -283,10 +283,10 @@ static struct dentry *autofs4_expire_direct(struct super_block *sb,
  *  - it is unused by any user process
  *  - it has been unused for exp_timeout time
  */
-static struct dentry *autofs4_expire_indirect(struct super_block *sb,
-                                              struct vfsmount *mnt,
-                                              struct autofs_sb_info *sbi,
-                                              int how)
+struct dentry *autofs4_expire_indirect(struct super_block *sb,
+                                       struct vfsmount *mnt,
+                                       struct autofs_sb_info *sbi,
+                                       int how)
 {
         unsigned long timeout;
         struct dentry *root = sb->s_root;
diff --git a/fs/autofs4/init.c b/fs/autofs4/init.c
index 723a1c5e361b..9722e4bd8957 100644
--- a/fs/autofs4/init.c
+++ b/fs/autofs4/init.c
@@ -29,11 +29,20 @@ static struct file_system_type autofs_fs_type = {
 
 static int __init init_autofs4_fs(void)
 {
-        return register_filesystem(&autofs_fs_type);
+        int err;
+
+        err = register_filesystem(&autofs_fs_type);
+        if (err)
+                return err;
+
+        autofs_dev_ioctl_init();
+
+        return err;
 }
 
 static void __exit exit_autofs4_fs(void)
 {
+        autofs_dev_ioctl_exit();
         unregister_filesystem(&autofs_fs_type);
 }