kernel-ark/fs/autofs/root.c
Arjan van de Ven 754661f143 [PATCH] mark struct inode_operations const 1
Many struct inode_operations in the kernel can be "const".  Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data.  In addition it'll catch accidental writes at compile time to
these shared resources.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:46 -08:00

566 lines
15 KiB
C

/* -*- 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 = iget(sb, ent->ino);
if (!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",
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 = &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;
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);
d_instantiate(dentry, iget(dir->i_sb,ent->ino));
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;
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);
d_instantiate(dentry, iget(dir->i_sb,ino));
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,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 ( !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;
}
}