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root/fs/autofs/root.c

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DEFINITIONS

This source file includes following definitions.
  1. autofs_root_readdir
  2. try_to_fill_dentry
  3. autofs_revalidate
  4. autofs_root_lookup
  5. autofs_root_symlink
  6. autofs_root_unlink
  7. autofs_root_rmdir
  8. autofs_root_mkdir
  9. autofs_get_set_timeout
  10. autofs_get_protover
  11. autofs_expire_run
  12. autofs_root_ioctl

/* -*- linux-c -*- --------------------------------------------------------- *
 *
 * linux/fs/autofs/root.c
 *
 *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
 *
 * 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 autofs_root_readdir(struct file *,void *,filldir_t);
static struct dentry *autofs_root_lookup(struct inode *,struct dentry *, struct nameidata *);
static int autofs_root_symlink(struct inode *,struct dentry *,const char *);
static int autofs_root_unlink(struct inode *,struct dentry *);
static int autofs_root_rmdir(struct inode *,struct dentry *);
static int autofs_root_mkdir(struct inode *,struct dentry *,int);
static int autofs_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);

const struct file_operations autofs_root_operations = {
        .read           = generic_read_dir,
        .readdir        = autofs_root_readdir,
        .ioctl          = autofs_root_ioctl,
};

const struct inode_operations autofs_root_inode_operations = {
        .lookup         = autofs_root_lookup,
        .unlink         = autofs_root_unlink,
        .symlink        = autofs_root_symlink,
        .mkdir          = autofs_root_mkdir,
        .rmdir          = autofs_root_rmdir,
};

static int autofs_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
        struct autofs_dir_ent *ent = NULL;
        struct autofs_dirhash *dirhash;
        struct autofs_sb_info *sbi;
        struct inode * inode = filp->f_path.dentry->d_inode;
        off_t onr, nr;

        lock_kernel();

        sbi = autofs_sbi(inode->i_sb);
        dirhash = &sbi->dirhash;
        nr = filp->f_pos;

        switch(nr)
        {
        case 0:
                if (filldir(dirent, ".", 1, nr, inode->i_ino, DT_DIR) < 0)
                        goto out;
                filp->f_pos = ++nr;
                /* fall through */
        case 1:
                if (filldir(dirent, "..", 2, nr, inode->i_ino, DT_DIR) < 0)
                        goto out;
                filp->f_pos = ++nr;
                /* fall through */
        default:
                while (onr = nr, ent = autofs_hash_enum(dirhash,&nr,ent)) {
                        if (!ent->dentry || d_mountpoint(ent->dentry)) {
                                if (filldir(dirent,ent->name,ent->len,onr,ent->ino,DT_UNKNOWN) < 0)
                                        goto out;
                                filp->f_pos = nr;
                        }
                }
                break;
        }

out:
        unlock_kernel();
        return 0;
}

static int try_to_fill_dentry(struct dentry *dentry, struct super_block *sb, struct autofs_sb_info *sbi)
{
        struct inode * inode;
        struct autofs_dir_ent *ent;
        int status = 0;

        if (!(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name))) {
                do {
                        if (status && dentry->d_inode) {
                                if (status != -ENOENT)
                                        printk("autofs warning: lookup failure on positive dentry, status = %d, name = %s\n", status, dentry->d_name.name);
                                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;
                        }
                        status = autofs_wait(sbi, &dentry->d_name);
                } while (!(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name)));
        }

        /* Abuse this field as a pointer to the directory entry, used to
           find the expire list pointers */
        dentry->d_time = (unsigned long) ent;
        
        if (!dentry->d_inode) {
                inode = autofs_iget(sb, ent->ino);
                if (IS_ERR(inode)) {
                        /* Failed, but leave pending for next time */
                        return 1;
                }
                dentry->d_inode = inode;
        }

        /* If this is a directory that isn't a mount point, bitch at the
           daemon and fix it in user space */
        if (S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry)) {
                return !autofs_wait(sbi, &dentry->d_name);
        }

        /* We don't update the usages for the autofs daemon itself, this
           is necessary for recursive autofs mounts */
        if (!autofs_oz_mode(sbi)) {
                autofs_update_usage(&sbi->dirhash,ent);
        }

        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 autofs_revalidate(struct dentry * dentry, struct nameidata *nd)
{
        struct inode * dir;
        struct autofs_sb_info *sbi;
        struct autofs_dir_ent *ent;
        int res;

        lock_kernel();
        dir = dentry->d_parent->d_inode;
        sbi = autofs_sbi(dir->i_sb);

        /* Pending dentry */
        if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
                if (autofs_oz_mode(sbi))
                        res = 1;
                else
                        res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
                unlock_kernel();
                return res;
        }

        /* Negative dentry.. invalidate if "old" */
        if (!dentry->d_inode) {
                unlock_kernel();
                return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
        }
                
        /* Check for a non-mountpoint directory */
        if (S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry)) {
                if (autofs_oz_mode(sbi))
                        res = 1;
                else
                        res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
                unlock_kernel();
                return res;
        }

        /* Update the usage list */
        if (!autofs_oz_mode(sbi)) {
                ent = (struct autofs_dir_ent *) dentry->d_time;
                if (ent)
                        autofs_update_usage(&sbi->dirhash,ent);
        }
        unlock_kernel();
        return 1;
}

static struct dentry_operations autofs_dentry_operations = {
        .d_revalidate   = autofs_revalidate,
};

static struct dentry *autofs_root_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
        struct autofs_sb_info *sbi;
        int oz_mode;

        DPRINTK(("autofs_root_lookup: name = "));
        lock_kernel();
        autofs_say(dentry->d_name.name,dentry->d_name.len);

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

        sbi = autofs_sbi(dir->i_sb);

        oz_mode = autofs_oz_mode(sbi);
        DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, "
                                "oz_mode = %d\n", task_pid_nr(current),
                                task_pgrp_nr(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 = &autofs_dentry_operations;
        dentry->d_flags |= DCACHE_AUTOFS_PENDING;
        d_add(dentry, NULL);

        mutex_unlock(&dir->i_mutex);
        autofs_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)) {
                                unlock_kernel();
                                return ERR_PTR(-ERESTARTNOINTR);
                        }
                }
        }
        unlock_kernel();

        /*
         * 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 autofs_root_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
{
        struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
        struct autofs_dirhash *dh = &sbi->dirhash;
        struct autofs_dir_ent *ent;
        unsigned int n;
        int slsize;
        struct autofs_symlink *sl;
        struct inode *inode;

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

        lock_kernel();
        if (!autofs_oz_mode(sbi)) {
                unlock_kernel();
                return -EACCES;
        }

        if (autofs_hash_lookup(dh, &dentry->d_name)) {
                unlock_kernel();
                return -EEXIST;
        }

        n = find_first_zero_bit(sbi->symlink_bitmap,AUTOFS_MAX_SYMLINKS);
        if (n >= AUTOFS_MAX_SYMLINKS) {
                unlock_kernel();
                return -ENOSPC;
        }

        set_bit(n,sbi->symlink_bitmap);
        sl = &sbi->symlink[n];
        sl->len = strlen(symname);
        sl->data = kmalloc(slsize = sl->len+1, GFP_KERNEL);
        if (!sl->data) {
                clear_bit(n,sbi->symlink_bitmap);
                unlock_kernel();
                return -ENOSPC;
        }

        ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
        if (!ent) {
                kfree(sl->data);
                clear_bit(n,sbi->symlink_bitmap);
                unlock_kernel();
                return -ENOSPC;
        }

        ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
        if (!ent->name) {
                kfree(sl->data);
                kfree(ent);
                clear_bit(n,sbi->symlink_bitmap);
                unlock_kernel();
                return -ENOSPC;
        }

        memcpy(sl->data,symname,slsize);
        sl->mtime = get_seconds();

        ent->ino = AUTOFS_FIRST_SYMLINK + n;
        ent->hash = dentry->d_name.hash;
        memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
        ent->dentry = NULL;     /* We don't keep the dentry for symlinks */

        autofs_hash_insert(dh,ent);

        inode = autofs_iget(dir->i_sb, ent->ino);
        if (IS_ERR(inode))
                return PTR_ERR(inode);

        d_instantiate(dentry, inode);
        unlock_kernel();
        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, which we
 * obviously do not want (we're dropping the entry not because it
 * doesn't exist, but because it has timed out).
 *
 * Also see autofs_root_rmdir()..
 */
static int autofs_root_unlink(struct inode *dir, struct dentry *dentry)
{
        struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
        struct autofs_dirhash *dh = &sbi->dirhash;
        struct autofs_dir_ent *ent;
        unsigned int n;

        /* This allows root to remove symlinks */
        lock_kernel();
        if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN)) {
                unlock_kernel();
                return -EACCES;
        }

        ent = autofs_hash_lookup(dh, &dentry->d_name);
        if (!ent) {
                unlock_kernel();
                return -ENOENT;
        }

        n = ent->ino - AUTOFS_FIRST_SYMLINK;
        if (n >= AUTOFS_MAX_SYMLINKS) {
                unlock_kernel();
                return -EISDIR; /* It's a directory, dummy */
        }
        if (!test_bit(n,sbi->symlink_bitmap)) {
                unlock_kernel();
                return -EINVAL; /* Nonexistent symlink?  Shouldn't happen */
        }
        
        dentry->d_time = (unsigned long)(struct autofs_dirhash *)NULL;
        autofs_hash_delete(ent);
        clear_bit(n,sbi->symlink_bitmap);
        kfree(sbi->symlink[n].data);
        d_drop(dentry);
        
        unlock_kernel();
        return 0;
}

static int autofs_root_rmdir(struct inode *dir, struct dentry *dentry)
{
        struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
        struct autofs_dirhash *dh = &sbi->dirhash;
        struct autofs_dir_ent *ent;

        lock_kernel();
        if (!autofs_oz_mode(sbi)) {
                unlock_kernel();
                return -EACCES;
        }

        ent = autofs_hash_lookup(dh, &dentry->d_name);
        if (!ent) {
                unlock_kernel();
                return -ENOENT;
        }

        if ((unsigned int)ent->ino < AUTOFS_FIRST_DIR_INO) {
                unlock_kernel();
                return -ENOTDIR; /* Not a directory */
        }

        if (ent->dentry != dentry) {
                printk("autofs_rmdir: odentry != dentry for entry %s\n", dentry->d_name.name);
        }

        dentry->d_time = (unsigned long)(struct autofs_dir_ent *)NULL;
        autofs_hash_delete(ent);
        drop_nlink(dir);
        d_drop(dentry);
        unlock_kernel();

        return 0;
}

static int autofs_root_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
        struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
        struct autofs_dirhash *dh = &sbi->dirhash;
        struct autofs_dir_ent *ent;
        struct inode *inode;
        ino_t ino;

        lock_kernel();
        if (!autofs_oz_mode(sbi)) {
                unlock_kernel();
                return -EACCES;
        }

        ent = autofs_hash_lookup(dh, &dentry->d_name);
        if (ent) {
                unlock_kernel();
                return -EEXIST;
        }

        if (sbi->next_dir_ino < AUTOFS_FIRST_DIR_INO) {
                printk("autofs: Out of inode numbers -- what the heck did you do??\n");
                unlock_kernel();
                return -ENOSPC;
        }
        ino = sbi->next_dir_ino++;

        ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
        if (!ent) {
                unlock_kernel();
                return -ENOSPC;
        }

        ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
        if (!ent->name) {
                kfree(ent);
                unlock_kernel();
                return -ENOSPC;
        }

        ent->hash = dentry->d_name.hash;
        memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
        ent->ino = ino;
        ent->dentry = dentry;
        autofs_hash_insert(dh,ent);

        inc_nlink(dir);

        inode = autofs_iget(dir->i_sb, ino);
        if (IS_ERR(inode)) {
                drop_nlink(dir);
                return PTR_ERR(inode);
        }

        d_instantiate(dentry, inode);
        unlock_kernel();

        return 0;
}

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

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

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

        return 0;
}

/* Return protocol version */
static inline int autofs_get_protover(int __user *p)
{
        return put_user(AUTOFS_PROTO_VERSION, p);
}

/* Perform an expiry operation */
static inline int autofs_expire_run(struct super_block *sb,
                                    struct autofs_sb_info *sbi,
                                    struct vfsmount *mnt,
                                    struct autofs_packet_expire __user *pkt_p)
{
        struct autofs_dir_ent *ent;
        struct autofs_packet_expire pkt;

        memset(&pkt,0,sizeof pkt);

        pkt.hdr.proto_version = AUTOFS_PROTO_VERSION;
        pkt.hdr.type = autofs_ptype_expire;

        if (!sbi->exp_timeout || !(ent = autofs_expire(sb,sbi,mnt)))
                return -EAGAIN;

        pkt.len = ent->len;
        memcpy(pkt.name, ent->name, pkt.len);
        pkt.name[pkt.len] = '\0';

        if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)))
                return -EFAULT;

        return 0;
}

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

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

        if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
             _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
                return -ENOTTY;
        
        if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
                return -EPERM;
        
        switch(cmd) {
        case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
                return autofs_wait_release(sbi,(autofs_wqt_t)arg,0);
        case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
                return autofs_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
        case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
                autofs_catatonic_mode(sbi);
                return 0;
        case AUTOFS_IOC_PROTOVER: /* Get protocol version */
                return autofs_get_protover(argp);
        case AUTOFS_IOC_SETTIMEOUT:
                return autofs_get_set_timeout(sbi, argp);
        case AUTOFS_IOC_EXPIRE:
                return autofs_expire_run(inode->i_sb, sbi, filp->f_path.mnt,
                                         argp);
        default:
                return -ENOSYS;
        }
}

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