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/* -*- c -*- --------------------------------------------------------------- *

 *

 * linux/fs/autofs/root.c

 *

 *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved

 *  Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>

 *

 * 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/errno.h>

#include <linux/stat.h>

#include <linux/param.h>

#include <linux/sched.h>

#include <linux/smp_lock.h>

#include "autofs_i.h"

static struct dentry *autofs4_dir_lookup(struct inode *,struct dentry *);

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 struct dentry *autofs4_root_lookup(struct inode *,struct dentry *);

struct file_operations autofs4_root_operations = {

        open:           dcache_dir_open,

        release:        dcache_dir_close,

        llseek:         dcache_dir_lseek,

        read:           generic_read_dir,

        readdir:        dcache_readdir,

        fsync:          dcache_dir_fsync,

        ioctl:          autofs4_root_ioctl,

};

struct inode_operations autofs4_root_inode_operations = {

        lookup:         autofs4_root_lookup,

        unlink:         autofs4_dir_unlink,

        symlink:        autofs4_dir_symlink,

        mkdir:          autofs4_dir_mkdir,

        rmdir:          autofs4_dir_rmdir,

};

struct inode_operations autofs4_dir_inode_operations = {

        lookup:         autofs4_dir_lookup,

        unlink:         autofs4_dir_unlink,

        symlink:        autofs4_dir_symlink,

        mkdir:          autofs4_dir_mkdir,

        rmdir:          autofs4_dir_rmdir,

};

/* Update usage from here to top of tree, so that scan of

   top-level directories will give a useful result */

static void autofs4_update_usage(struct dentry *dentry)

{

        struct dentry *top = dentry->d_sb->s_root;

        for(; dentry != top; dentry = dentry->d_parent) {

                struct autofs_info *ino = autofs4_dentry_ino(dentry);

                if (ino) {

                        update_atime(dentry->d_inode);

                        ino->last_used = jiffies;

                }

        }

}

static int try_to_fill_dentry(struct dentry *dentry,

                              struct super_block *sb,

                              struct autofs_sb_info *sbi)

{

        struct autofs_info *de_info = 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 (de_info && (de_info->flags & AUTOFS_INF_EXPIRING)) {

                DPRINTK(("try_to_fill_entry: waiting for expire %p name=%.*s, flags&PENDING=%s de_info=%p de_info->flags=%x\n",

                         dentry, dentry->d_name.len, dentry->d_name.name,

                         dentry->d_flags & DCACHE_AUTOFS_PENDING?"t":"f",

                         de_info, de_info?de_info->flags:0));

                status = autofs4_wait(sbi, &dentry->d_name, NFY_NONE);

                DPRINTK(("try_to_fill_entry: expire done status=%d\n", status));

                return 0;

        }

        DPRINTK(("try_to_fill_entry: dentry=%p %.*s ino=%p\n",

                 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 */

        while(dentry->d_inode == NULL) {

                DPRINTK(("try_to_fill_entry: waiting for mount name=%.*s, de_info=%p de_info->flags=%x\n",

                         dentry->d_name.len, dentry->d_name.name,

                         de_info, de_info?de_info->flags:0));

                status = autofs4_wait(sbi, &dentry->d_name, NFY_MOUNT);

                DPRINTK(("try_to_fill_entry: mount done status=%d\n", status));

                if (status && dentry->d_inode)

                        return 0; /* Try to get the kernel to invalidate this dentry */

                /* Turn this into a real negative dentry? */

                if (status == -ENOENT) {

                        dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;

                        dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;

                        return 1;

                } else if (status) {

                        /* Return a negative dentry, but leave it "pending" */

                        return 1;

                }

        }

        /* If this is an unused directory that isn't a mount point,

           bitch at the daemon and fix it in user space */

        spin_lock(&dcache_lock);

        if (S_ISDIR(dentry->d_inode->i_mode) &&

            !d_mountpoint(dentry) &&

            list_empty(&dentry->d_subdirs)) {

                DPRINTK(("try_to_fill_entry: mounting existing dir\n"));

                spin_unlock(&dcache_lock);

                return autofs4_wait(sbi, &dentry->d_name, NFY_MOUNT) == 0;

        }

        spin_unlock(&dcache_lock);

        /* We don't update the usages for the autofs daemon itself, this

           is necessary for recursive autofs mounts */

        if (!autofs4_oz_mode(sbi))

                autofs4_update_usage(dentry);

        dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;

        return 1;

}

/*

 * 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_root_revalidate(struct dentry * dentry, int flags)

{

        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);

        /* Pending dentry */

        if (autofs4_ispending(dentry)) {

                if (autofs4_oz_mode(sbi))

                        return 1;

                else

                        return try_to_fill_dentry(dentry, dir->i_sb, sbi);

        }

        /* Negative dentry.. invalidate if "old" */

        if (dentry->d_inode == NULL)

                return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);

        /* Check for a non-mountpoint directory with no contents */

        spin_lock(&dcache_lock);

        if (S_ISDIR(dentry->d_inode->i_mode) &&

            !d_mountpoint(dentry) &&

            list_empty(&dentry->d_subdirs)) {

                DPRINTK(("autofs_root_revalidate: dentry=%p %.*s, emptydir\n",

                         dentry, dentry->d_name.len, dentry->d_name.name));

                spin_unlock(&dcache_lock);

                if (oz_mode)

                        return 1;

                else

                        return try_to_fill_dentry(dentry, dir->i_sb, sbi);

        }

        spin_unlock(&dcache_lock);

        /* Update the usage list */

        if (!oz_mode)

                autofs4_update_usage(dentry);

        return 1;

}

static int autofs4_revalidate(struct dentry *dentry, int flags)

{

        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);

        if (!autofs4_oz_mode(sbi))

                autofs4_update_usage(dentry);

        return 1;

}

static void autofs4_dentry_release(struct dentry *de)

{

        struct autofs_info *inf;

        lock_kernel();

        DPRINTK(("autofs4_dentry_release: releasing %p\n", de));

        inf = autofs4_dentry_ino(de);

        de->d_fsdata = NULL;

        if (inf) {

                inf->dentry = NULL;

                inf->inode = NULL;

                autofs4_free_ino(inf);

        }

        unlock_kernel();

}

/* For dentries of directories in the root dir */

static struct dentry_operations autofs4_root_dentry_operations = {

        d_revalidate:   autofs4_root_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 non-root dirs never find anything - if it's there, it's

   already in the dcache */

static struct dentry *autofs4_dir_lookup(struct inode *dir, struct dentry *dentry)

{

#if 0

        DPRINTK(("autofs_dir_lookup: ignoring lookup of %.*s/%.*s\n",

                 dentry->d_parent->d_name.len, dentry->d_parent->d_name.name,

                 dentry->d_name.len, dentry->d_name.name));

#endif

        dentry->d_fsdata = NULL;

        d_add(dentry, NULL);

        return NULL;

}

/* Lookups in the root directory */

static struct dentry *autofs4_root_lookup(struct inode *dir, struct dentry *dentry)

{

        struct autofs_sb_info *sbi;

        int oz_mode;

        DPRINTK(("autofs_root_lookup: name = %.*s\n",

                 dentry->d_name.len, dentry->d_name.name));

        if (dentry->d_name.len > NAME_MAX)

                return ERR_PTR(-ENAMETOOLONG);/* File name too long to exist */

        sbi = autofs4_sbi(dir->i_sb);

        oz_mode = autofs4_oz_mode(sbi);

        DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",

                 current->pid, current->pgrp, 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)

                dentry->d_flags |= DCACHE_AUTOFS_PENDING;

        dentry->d_fsdata = NULL;

        d_add(dentry, NULL);

        if (dentry->d_op && dentry->d_op->d_revalidate) {

                up(&dir->i_sem);

                (dentry->d_op->d_revalidate)(dentry, 0);

                down(&dir->i_sem);

        }

        /*

         * 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) {

                if (signal_pending(current))

                        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 inode *inode;

        char *cp;

        DPRINTK(("autofs_dir_symlink: %s <- %.*s\n", 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);

        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 autofs_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);

        /* This allows root to remove symlinks */

        if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )

                return -EACCES;

        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);

        if (!autofs4_oz_mode(sbi))

                return -EACCES;

        spin_lock(&dcache_lock);

        if (!list_empty(&dentry->d_subdirs)) {

                spin_unlock(&dcache_lock);

                return -ENOTEMPTY;

        }

        list_del_init(&dentry->d_hash);

        spin_unlock(&dcache_lock);

        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 inode *inode;

        if ( !autofs4_oz_mode(sbi) )

                return -EACCES;

        DPRINTK(("autofs_dir_mkdir: dentry %p, creating %.*s\n",

                 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);

        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 *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 *p)

{

        return put_user(sbi->version, p);

}

/* Identify autofs_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);

        DPRINTK(("autofs_ioctl: cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",

                 cmd,arg,sbi,current->pgrp));

        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, (int *)arg);

        case AUTOFS_IOC_SETTIMEOUT:

                return autofs4_get_set_timeout(sbi,(unsigned long *)arg);

        /* return a single thing to expire */

        case AUTOFS_IOC_EXPIRE:

                return autofs4_expire_run(inode->i_sb,filp->f_vfsmnt,sbi,

                                          (struct autofs_packet_expire *)arg);

        /* 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,

                                            (int *)arg);

        default:

                return -ENOSYS;

        }

}