[libata] minor PCI IDE probe fixes and cleanups

[usb.git] / fs / autofs4 / root.c

/* -*- c -*- --------------------------------------------------------------- *
 *
 * linux/fs/autofs/root.c
 *
 *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
 *  Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
 *  Copyright 2001-2006 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/capability.h>
#include <linux/errno.h>
#include <linux/stat.h>
#include <linux/param.h>
#include <linux/time.h>
#include <linux/smp_lock.h>
#include "autofs_i.h"

static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
static int autofs4_dir_unlink(struct inode *,struct dentry *);
static int autofs4_dir_rmdir(struct inode *,struct dentry *);
static int autofs4_dir_mkdir(struct inode *,struct dentry *,int);
static int autofs4_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
static int autofs4_dir_open(struct inode *inode, struct file *file);
static int autofs4_dir_close(struct inode *inode, struct file *file);
static int autofs4_dir_readdir(struct file * filp, void * dirent, filldir_t filldir);
static int autofs4_root_readdir(struct file * filp, void * dirent, filldir_t filldir);
static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
static void *autofs4_follow_link(struct dentry *, struct nameidata *);

const struct file_operations autofs4_root_operations = {
        .open           = dcache_dir_open,
        .release        = dcache_dir_close,
        .read           = generic_read_dir,
        .readdir        = autofs4_root_readdir,
        .ioctl          = autofs4_root_ioctl,
};

const struct file_operations autofs4_dir_operations = {
        .open           = autofs4_dir_open,
        .release        = autofs4_dir_close,
        .read           = generic_read_dir,
        .readdir        = autofs4_dir_readdir,
};

struct inode_operations autofs4_indirect_root_inode_operations = {
        .lookup         = autofs4_lookup,
        .unlink         = autofs4_dir_unlink,
        .symlink        = autofs4_dir_symlink,
        .mkdir          = autofs4_dir_mkdir,
        .rmdir          = autofs4_dir_rmdir,
};

struct inode_operations autofs4_direct_root_inode_operations = {
        .lookup         = autofs4_lookup,
        .unlink         = autofs4_dir_unlink,
        .mkdir          = autofs4_dir_mkdir,
        .rmdir          = autofs4_dir_rmdir,
        .follow_link    = autofs4_follow_link,
};

struct inode_operations autofs4_dir_inode_operations = {
        .lookup         = autofs4_lookup,
        .unlink         = autofs4_dir_unlink,
        .symlink        = autofs4_dir_symlink,
        .mkdir          = autofs4_dir_mkdir,
        .rmdir          = autofs4_dir_rmdir,
};

static int autofs4_root_readdir(struct file *file, void *dirent,
                                filldir_t filldir)
{
        struct autofs_sb_info *sbi = autofs4_sbi(file->f_dentry->d_sb);
        int oz_mode = autofs4_oz_mode(sbi);

        DPRINTK("called, filp->f_pos = %lld", file->f_pos);

        /*
         * Don't set reghost flag if:
         * 1) f_pos is larger than zero -- we've already been here.
         * 2) we haven't even enabled reghosting in the 1st place.
         * 3) this is the daemon doing a readdir
         */
        if (oz_mode && file->f_pos == 0 && sbi->reghost_enabled)
                sbi->needs_reghost = 1;

        DPRINTK("needs_reghost = %d", sbi->needs_reghost);

        return dcache_readdir(file, dirent, filldir);
}

static int autofs4_dir_open(struct inode *inode, struct file *file)
{
        struct dentry *dentry = file->f_dentry;
        struct vfsmount *mnt = file->f_vfsmnt;
        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
        struct dentry *cursor;
        int status;

        status = dcache_dir_open(inode, file);
        if (status)
                goto out;

        cursor = file->private_data;
        cursor->d_fsdata = NULL;

        DPRINTK("file=%p dentry=%p %.*s",
                file, dentry, dentry->d_name.len, dentry->d_name.name);

        if (autofs4_oz_mode(sbi))
                goto out;

        if (autofs4_ispending(dentry)) {
                DPRINTK("dentry busy");
                dcache_dir_close(inode, file);
                status = -EBUSY;
                goto out;
        }

        status = -ENOENT;
        if (!d_mountpoint(dentry) && dentry->d_op && dentry->d_op->d_revalidate) {
                struct nameidata nd;
                int empty, ret;

                /* In case there are stale directory dentrys from a failed mount */
                spin_lock(&dcache_lock);
                empty = list_empty(&dentry->d_subdirs);
                spin_unlock(&dcache_lock);

                if (!empty)
                        d_invalidate(dentry);

                nd.flags = LOOKUP_DIRECTORY;
                ret = (dentry->d_op->d_revalidate)(dentry, &nd);

                if (ret <= 0) {
                        if (ret < 0)
                                status = ret;
                        dcache_dir_close(inode, file);
                        goto out;
                }
        }

        if (d_mountpoint(dentry)) {
                struct file *fp = NULL;
                struct vfsmount *fp_mnt = mntget(mnt);
                struct dentry *fp_dentry = dget(dentry);

                if (!autofs4_follow_mount(&fp_mnt, &fp_dentry)) {
                        dput(fp_dentry);
                        mntput(fp_mnt);
                        dcache_dir_close(inode, file);
                        goto out;
                }

                fp = dentry_open(fp_dentry, fp_mnt, file->f_flags);
                status = PTR_ERR(fp);
                if (IS_ERR(fp)) {
                        dcache_dir_close(inode, file);
                        goto out;
                }
                cursor->d_fsdata = fp;
        }
        return 0;
out:
        return status;
}

static int autofs4_dir_close(struct inode *inode, struct file *file)
{
        struct dentry *dentry = file->f_dentry;
        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
        struct dentry *cursor = file->private_data;
        int status = 0;

        DPRINTK("file=%p dentry=%p %.*s",
                file, dentry, dentry->d_name.len, dentry->d_name.name);

        if (autofs4_oz_mode(sbi))
                goto out;

        if (autofs4_ispending(dentry)) {
                DPRINTK("dentry busy");
                status = -EBUSY;
                goto out;
        }

        if (d_mountpoint(dentry)) {
                struct file *fp = cursor->d_fsdata;
                if (!fp) {
                        status = -ENOENT;
                        goto out;
                }
                filp_close(fp, current->files);
        }
out:
        dcache_dir_close(inode, file);
        return status;
}

static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldir)
{
        struct dentry *dentry = file->f_dentry;
        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
        struct dentry *cursor = file->private_data;
        int status;

        DPRINTK("file=%p dentry=%p %.*s",
                file, dentry, dentry->d_name.len, dentry->d_name.name);

        if (autofs4_oz_mode(sbi))
                goto out;

        if (autofs4_ispending(dentry)) {
                DPRINTK("dentry busy");
                return -EBUSY;
        }

        if (d_mountpoint(dentry)) {
                struct file *fp = cursor->d_fsdata;

                if (!fp)
                        return -ENOENT;

                if (!fp->f_op || !fp->f_op->readdir)
                        goto out;

                status = vfs_readdir(fp, filldir, dirent);
                file->f_pos = fp->f_pos;
                if (status)
                        autofs4_copy_atime(file, fp);
                return status;
        }
out:
        return dcache_readdir(file, dirent, filldir);
}

static int try_to_fill_dentry(struct dentry *dentry, int flags)
{
        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
        struct autofs_info *ino = autofs4_dentry_ino(dentry);
        int status = 0;

        /* Block on any pending expiry here; invalidate the dentry
           when expiration is done to trigger mount request with a new
           dentry */
        if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
                DPRINTK("waiting for expire %p name=%.*s",
                         dentry, dentry->d_name.len, dentry->d_name.name);

                status = autofs4_wait(sbi, dentry, NFY_NONE);

                DPRINTK("expire done status=%d", status);

                /*
                 * If the directory still exists the mount request must
                 * continue otherwise it can't be followed at the right
                 * time during the walk.
                 */
                status = d_invalidate(dentry);
                if (status != -EBUSY)
                        return -ENOENT;
        }

        DPRINTK("dentry=%p %.*s ino=%p",
                 dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);

        /*
         * Wait for a pending mount, triggering one if there
         * isn't one already
         */
        if (dentry->d_inode == NULL) {
                DPRINTK("waiting for mount name=%.*s",
                         dentry->d_name.len, dentry->d_name.name);

                status = autofs4_wait(sbi, dentry, NFY_MOUNT);

                DPRINTK("mount done status=%d", status);

                if (status && dentry->d_inode)
                        return status; /* Try to get the kernel to invalidate this dentry */

                /* Turn this into a real negative dentry? */
                if (status == -ENOENT) {
                        spin_lock(&dentry->d_lock);
                        dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
                        spin_unlock(&dentry->d_lock);
                        return status;
                } else if (status) {
                        /* Return a negative dentry, but leave it "pending" */
                        return status;
                }
        /* Trigger mount for path component or follow link */
        } else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
                        current->link_count) {
                DPRINTK("waiting for mount name=%.*s",
                        dentry->d_name.len, dentry->d_name.name);

                spin_lock(&dentry->d_lock);
                dentry->d_flags |= DCACHE_AUTOFS_PENDING;
                spin_unlock(&dentry->d_lock);
                status = autofs4_wait(sbi, dentry, NFY_MOUNT);

                DPRINTK("mount done status=%d", status);

                if (status) {
                        spin_lock(&dentry->d_lock);
                        dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
                        spin_unlock(&dentry->d_lock);
                        return status;
                }
        }

        /* Initialize expiry counter after successful mount */
        if (ino)
                ino->last_used = jiffies;

        spin_lock(&dentry->d_lock);
        dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
        spin_unlock(&dentry->d_lock);
        return status;
}

/* For autofs direct mounts the follow link triggers the mount */
static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
{
        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
        struct autofs_info *ino = autofs4_dentry_ino(dentry);
        int oz_mode = autofs4_oz_mode(sbi);
        unsigned int lookup_type;
        int status;

        DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
                dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
                nd->flags);

        /* If it's our master or we shouldn't trigger a mount we're done */
        lookup_type = nd->flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY);
        if (oz_mode || !lookup_type)
                goto done;

        /* If an expire request is pending wait for it. */
        if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
                DPRINTK("waiting for active request %p name=%.*s",
                        dentry, dentry->d_name.len, dentry->d_name.name);

                status = autofs4_wait(sbi, dentry, NFY_NONE);

                DPRINTK("request done status=%d", status);
        }

        /*
         * If the dentry contains directories then it is an
         * autofs multi-mount with no root mount offset. So
         * don't try to mount it again.
         */
        spin_lock(&dcache_lock);
        if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
                spin_unlock(&dcache_lock);

                status = try_to_fill_dentry(dentry, 0);
                if (status)
                        goto out_error;

                /*
                 * The mount succeeded but if there is no root mount
                 * it must be an autofs multi-mount with no root offset
                 * so we don't need to follow the mount.
                 */
                if (d_mountpoint(dentry)) {
                        if (!autofs4_follow_mount(&nd->mnt, &nd->dentry)) {
                                status = -ENOENT;
                                goto out_error;
                        }
                }

                goto done;
        }
        spin_unlock(&dcache_lock);

done:
        return NULL;

out_error:
        path_release(nd);
        return ERR_PTR(status);
}

/*
 * Revalidate is called on every cache lookup.  Some of those
 * cache lookups may actually happen while the dentry is not
 * yet completely filled in, and revalidate has to delay such
 * lookups..
 */
static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
{
        struct inode *dir = dentry->d_parent->d_inode;
        struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
        int oz_mode = autofs4_oz_mode(sbi);
        int flags = nd ? nd->flags : 0;
        int status = 1;

        /* Pending dentry */
        if (autofs4_ispending(dentry)) {
                /* The daemon never causes a mount to trigger */
                if (oz_mode)
                        return 1;

                /*
                 * A zero status is success otherwise we have a
                 * negative error code.
                 */
                status = try_to_fill_dentry(dentry, flags);
                if (status == 0)
                                return 1;

                return status;
        }

        /* Negative dentry.. invalidate if "old" */
        if (dentry->d_inode == NULL)
                return 0;

        /* Check for a non-mountpoint directory with no contents */
        spin_lock(&dcache_lock);
        if (S_ISDIR(dentry->d_inode->i_mode) &&
            !d_mountpoint(dentry) && 
            __simple_empty(dentry)) {
                DPRINTK("dentry=%p %.*s, emptydir",
                         dentry, dentry->d_name.len, dentry->d_name.name);
                spin_unlock(&dcache_lock);
                /* The daemon never causes a mount to trigger */
                if (oz_mode)
                        return 1;

                /*
                 * A zero status is success otherwise we have a
                 * negative error code.
                 */
                status = try_to_fill_dentry(dentry, flags);
                if (status == 0)
                        return 1;

                return status;
        }
        spin_unlock(&dcache_lock);

        return 1;
}

void autofs4_dentry_release(struct dentry *de)
{
        struct autofs_info *inf;

        DPRINTK("releasing %p", de);

        inf = autofs4_dentry_ino(de);
        de->d_fsdata = NULL;

        if (inf) {
                inf->dentry = NULL;
                inf->inode = NULL;

                autofs4_free_ino(inf);
        }
}

/* For dentries of directories in the root dir */
static struct dentry_operations autofs4_root_dentry_operations = {
        .d_revalidate   = autofs4_revalidate,
        .d_release      = autofs4_dentry_release,
};

/* For other dentries */
static struct dentry_operations autofs4_dentry_operations = {
        .d_revalidate   = autofs4_revalidate,
        .d_release      = autofs4_dentry_release,
};

/* Lookups in the root directory */
static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
        struct autofs_sb_info *sbi;
        int oz_mode;

        DPRINTK("name = %.*s",
                dentry->d_name.len, dentry->d_name.name);

        /* File name too long to exist */
        if (dentry->d_name.len > NAME_MAX)
                return ERR_PTR(-ENAMETOOLONG);

        sbi = autofs4_sbi(dir->i_sb);
        oz_mode = autofs4_oz_mode(sbi);

        DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
                 current->pid, process_group(current), sbi->catatonic, oz_mode);

        /*
         * Mark the dentry incomplete, but add it. This is needed so
         * that the VFS layer knows about the dentry, and we can count
         * on catching any lookups through the revalidate.
         *
         * Let all the hard work be done by the revalidate function that
         * needs to be able to do this anyway..
         *
         * We need to do this before we release the directory semaphore.
         */
        dentry->d_op = &autofs4_root_dentry_operations;

        if (!oz_mode) {
                spin_lock(&dentry->d_lock);
                dentry->d_flags |= DCACHE_AUTOFS_PENDING;
                spin_unlock(&dentry->d_lock);
        }
        dentry->d_fsdata = NULL;
        d_add(dentry, NULL);

        if (dentry->d_op && dentry->d_op->d_revalidate) {
                mutex_unlock(&dir->i_mutex);
                (dentry->d_op->d_revalidate)(dentry, nd);
                mutex_lock(&dir->i_mutex);
        }

        /*
         * If we are still pending, check if we had to handle
         * a signal. If so we can force a restart..
         */
        if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
                /* See if we were interrupted */
                if (signal_pending(current)) {
                        sigset_t *sigset = &current->pending.signal;
                        if (sigismember (sigset, SIGKILL) ||
                            sigismember (sigset, SIGQUIT) ||
                            sigismember (sigset, SIGINT)) {
                            return ERR_PTR(-ERESTARTNOINTR);
                        }
                }
        }

        /*
         * If this dentry is unhashed, then we shouldn't honour this
         * lookup even if the dentry is positive.  Returning ENOENT here
         * doesn't do the right thing for all system calls, but it should
         * be OK for the operations we permit from an autofs.
         */
        if (dentry->d_inode && d_unhashed(dentry))
                return ERR_PTR(-ENOENT);

        return NULL;
}

static int autofs4_dir_symlink(struct inode *dir, 
                               struct dentry *dentry,
                               const char *symname)
{
        struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
        struct autofs_info *ino = autofs4_dentry_ino(dentry);
        struct autofs_info *p_ino;
        struct inode *inode;
        char *cp;

        DPRINTK("%s <- %.*s", symname,
                dentry->d_name.len, dentry->d_name.name);

        if (!autofs4_oz_mode(sbi))
                return -EACCES;

        ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
        if (ino == NULL)
                return -ENOSPC;

        ino->size = strlen(symname);
        ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);

        if (cp == NULL) {
                kfree(ino);
                return -ENOSPC;
        }

        strcpy(cp, symname);

        inode = autofs4_get_inode(dir->i_sb, ino);
        d_instantiate(dentry, inode);

        if (dir == dir->i_sb->s_root->d_inode)
                dentry->d_op = &autofs4_root_dentry_operations;
        else
                dentry->d_op = &autofs4_dentry_operations;

        dentry->d_fsdata = ino;
        ino->dentry = dget(dentry);
        atomic_inc(&ino->count);
        p_ino = autofs4_dentry_ino(dentry->d_parent);
        if (p_ino && dentry->d_parent != dentry)
                atomic_inc(&p_ino->count);
        ino->inode = inode;

        dir->i_mtime = CURRENT_TIME;

        return 0;
}

/*
 * NOTE!
 *
 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 * that the file no longer exists. However, doing that means that the
 * VFS layer can turn the dentry into a negative dentry.  We don't want
 * this, because since the unlink is probably the result of an expire.
 * We simply d_drop it, which allows the dentry lookup to remount it
 * if necessary.
 *
 * If a process is blocked on the dentry waiting for the expire to finish,
 * it will invalidate the dentry and try to mount with a new one.
 *
 * Also see autofs4_dir_rmdir()..
 */
static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
{
        struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
        struct autofs_info *ino = autofs4_dentry_ino(dentry);
        struct autofs_info *p_ino;
        
        /* This allows root to remove symlinks */
        if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
                return -EACCES;

        if (atomic_dec_and_test(&ino->count)) {
                p_ino = autofs4_dentry_ino(dentry->d_parent);
                if (p_ino && dentry->d_parent != dentry)
                        atomic_dec(&p_ino->count);
        }
        dput(ino->dentry);

        dentry->d_inode->i_size = 0;
        dentry->d_inode->i_nlink = 0;

        dir->i_mtime = CURRENT_TIME;

        d_drop(dentry);

        return 0;
}

static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
{
        struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
        struct autofs_info *ino = autofs4_dentry_ino(dentry);
        struct autofs_info *p_ino;
        
        if (!autofs4_oz_mode(sbi))
                return -EACCES;

        spin_lock(&dcache_lock);
        if (!list_empty(&dentry->d_subdirs)) {
                spin_unlock(&dcache_lock);
                return -ENOTEMPTY;
        }
        spin_lock(&dentry->d_lock);
        __d_drop(dentry);
        spin_unlock(&dentry->d_lock);
        spin_unlock(&dcache_lock);

        if (atomic_dec_and_test(&ino->count)) {
                p_ino = autofs4_dentry_ino(dentry->d_parent);
                if (p_ino && dentry->d_parent != dentry)
                        atomic_dec(&p_ino->count);
        }
        dput(ino->dentry);
        dentry->d_inode->i_size = 0;
        dentry->d_inode->i_nlink = 0;

        if (dir->i_nlink)
                dir->i_nlink--;

        return 0;
}

static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
        struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
        struct autofs_info *ino = autofs4_dentry_ino(dentry);
        struct autofs_info *p_ino;
        struct inode *inode;

        if ( !autofs4_oz_mode(sbi) )
                return -EACCES;

        DPRINTK("dentry %p, creating %.*s",
                dentry, dentry->d_name.len, dentry->d_name.name);

        ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
        if (ino == NULL)
                return -ENOSPC;

        inode = autofs4_get_inode(dir->i_sb, ino);
        d_instantiate(dentry, inode);

        if (dir == dir->i_sb->s_root->d_inode)
                dentry->d_op = &autofs4_root_dentry_operations;
        else
                dentry->d_op = &autofs4_dentry_operations;

        dentry->d_fsdata = ino;
        ino->dentry = dget(dentry);
        atomic_inc(&ino->count);
        p_ino = autofs4_dentry_ino(dentry->d_parent);
        if (p_ino && dentry->d_parent != dentry)
                atomic_inc(&p_ino->count);
        ino->inode = inode;
        dir->i_nlink++;
        dir->i_mtime = CURRENT_TIME;

        return 0;
}

/* Get/set timeout ioctl() operation */
static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
                                         unsigned long __user *p)
{
        int rv;
        unsigned long ntimeout;

        if ( (rv = get_user(ntimeout, p)) ||
             (rv = put_user(sbi->exp_timeout/HZ, p)) )
                return rv;

        if ( ntimeout > ULONG_MAX/HZ )
                sbi->exp_timeout = 0;
        else
                sbi->exp_timeout = ntimeout * HZ;

        return 0;
}

/* Return protocol version */
static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
{
        return put_user(sbi->version, p);
}

/* Return protocol sub version */
static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
{
        return put_user(sbi->sub_version, p);
}

/*
 * Tells the daemon whether we need to reghost or not. Also, clears
 * the reghost_needed flag.
 */
static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
{
        int status;

        DPRINTK("returning %d", sbi->needs_reghost);

        status = put_user(sbi->needs_reghost, p);
        if ( status )
                return status;

        sbi->needs_reghost = 0;
        return 0;
}

/*
 * Enable / Disable reghosting ioctl() operation
 */
static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
{
        int status;
        int val;

        status = get_user(val, p);

        DPRINTK("reghost = %d", val);

        if (status)
                return status;

        /* turn on/off reghosting, with the val */
        sbi->reghost_enabled = val;
        return 0;
}

/*
* Tells the daemon whether it can umount the autofs mount.
*/
static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
{
        int status = 0;

        if (may_umount(mnt))
                status = 1;

        DPRINTK("returning %d", status);

        status = put_user(status, p);

        return status;
}

/* Identify autofs4_dentries - this is so we can tell if there's
   an extra dentry refcount or not.  We only hold a refcount on the
   dentry if its non-negative (ie, d_inode != NULL)
*/
int is_autofs4_dentry(struct dentry *dentry)
{
        return dentry && dentry->d_inode &&
                (dentry->d_op == &autofs4_root_dentry_operations ||
                 dentry->d_op == &autofs4_dentry_operations) &&
                dentry->d_fsdata != NULL;
}

/*
 * ioctl()'s on the root directory is the chief method for the daemon to
 * generate kernel reactions
 */
static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
                             unsigned int cmd, unsigned long arg)
{
        struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
        void __user *p = (void __user *)arg;

        DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
                cmd,arg,sbi,process_group(current));

        if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
             _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
                return -ENOTTY;
        
        if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
                return -EPERM;
        
        switch(cmd) {
        case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
                return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
        case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
                return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
        case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
                autofs4_catatonic_mode(sbi);
                return 0;
        case AUTOFS_IOC_PROTOVER: /* Get protocol version */
                return autofs4_get_protover(sbi, p);
        case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
                return autofs4_get_protosubver(sbi, p);
        case AUTOFS_IOC_SETTIMEOUT:
                return autofs4_get_set_timeout(sbi, p);

        case AUTOFS_IOC_TOGGLEREGHOST:
                return autofs4_toggle_reghost(sbi, p);
        case AUTOFS_IOC_ASKREGHOST:
                return autofs4_ask_reghost(sbi, p);

        case AUTOFS_IOC_ASKUMOUNT:
                return autofs4_ask_umount(filp->f_vfsmnt, p);

        /* return a single thing to expire */
        case AUTOFS_IOC_EXPIRE:
                return autofs4_expire_run(inode->i_sb,filp->f_vfsmnt,sbi, p);
        /* same as above, but can send multiple expires through pipe */
        case AUTOFS_IOC_EXPIRE_MULTI:
                return autofs4_expire_multi(inode->i_sb,filp->f_vfsmnt,sbi, p);

        default:
                return -ENOSYS;
        }
}