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root.c
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/* -*- c -*- --------------------------------------------------------------- *
*
* linux/fs/autofs/root.c
*
* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
* Copyright 1999-2000 Jeremy Fitzhardinge <[email protected]>
* Copyright 2001-2006 Ian Kent <[email protected]>
*
* 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 "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 struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
static void *autofs4_follow_link(struct dentry *, struct nameidata *);
#define TRIGGER_FLAGS (LOOKUP_CONTINUE | LOOKUP_DIRECTORY)
#define TRIGGER_INTENTS (LOOKUP_OPEN | LOOKUP_CREATE)
const struct file_operations autofs4_root_operations = {
.open = dcache_dir_open,
.release = dcache_dir_close,
.read = generic_read_dir,
.readdir = dcache_readdir,
.llseek = dcache_dir_lseek,
.ioctl = autofs4_root_ioctl,
};
const struct file_operations autofs4_dir_operations = {
.open = autofs4_dir_open,
.release = dcache_dir_close,
.read = generic_read_dir,
.readdir = dcache_readdir,
.llseek = dcache_dir_lseek,
};
const 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,
};
const 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,
};
const 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 void autofs4_add_active(struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
if (ino) {
spin_lock(&sbi->lookup_lock);
if (!ino->active_count) {
if (list_empty(&ino->active))
list_add(&ino->active, &sbi->active_list);
}
ino->active_count++;
spin_unlock(&sbi->lookup_lock);
}
return;
}
static void autofs4_del_active(struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
if (ino) {
spin_lock(&sbi->lookup_lock);
ino->active_count--;
if (!ino->active_count) {
if (!list_empty(&ino->active))
list_del_init(&ino->active);
}
spin_unlock(&sbi->lookup_lock);
}
return;
}
static void autofs4_add_rehash_entry(struct autofs_info *ino,
struct rehash_entry *entry)
{
entry->task = current;
INIT_LIST_HEAD(&entry->list);
list_add(&entry->list, &ino->rehash_list);
return;
}
static void autofs4_remove_rehash_entry(struct autofs_info *ino)
{
struct list_head *head = &ino->rehash_list;
struct rehash_entry *entry;
list_for_each_entry(entry, head, list) {
if (entry->task == current) {
list_del(&entry->list);
kfree(entry);
break;
}
}
return;
}
static void autofs4_remove_rehash_entrys(struct autofs_info *ino)
{
struct autofs_sb_info *sbi = ino->sbi;
struct rehash_entry *entry, *next;
struct list_head *head;
spin_lock(&sbi->fs_lock);
spin_lock(&sbi->lookup_lock);
if (!(ino->flags & AUTOFS_INF_REHASH)) {
spin_unlock(&sbi->lookup_lock);
spin_unlock(&sbi->fs_lock);
return;
}
ino->flags &= ~AUTOFS_INF_REHASH;
head = &ino->rehash_list;
list_for_each_entry_safe(entry, next, head, list) {
list_del(&entry->list);
kfree(entry);
}
spin_unlock(&sbi->lookup_lock);
spin_unlock(&sbi->fs_lock);
dput(ino->dentry);
return;
}
static void autofs4_revalidate_drop(struct dentry *dentry,
struct rehash_entry *entry)
{
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
/*
* Add to the active list so we can pick this up in
* ->lookup(). Also add an entry to a rehash list so
* we know when there are no dentrys in flight so we
* know when we can rehash the dentry.
*/
spin_lock(&sbi->lookup_lock);
if (list_empty(&ino->active))
list_add(&ino->active, &sbi->active_list);
autofs4_add_rehash_entry(ino, entry);
spin_unlock(&sbi->lookup_lock);
if (!(ino->flags & AUTOFS_INF_REHASH)) {
ino->flags |= AUTOFS_INF_REHASH;
dget(dentry);
spin_lock(&dentry->d_lock);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
}
return;
}
static void autofs4_revalidate_rehash(struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
if (ino->flags & AUTOFS_INF_REHASH) {
spin_lock(&sbi->lookup_lock);
autofs4_remove_rehash_entry(ino);
if (list_empty(&ino->rehash_list)) {
spin_unlock(&sbi->lookup_lock);
ino->flags &= ~AUTOFS_INF_REHASH;
d_rehash(dentry);
dput(ino->dentry);
} else
spin_unlock(&sbi->lookup_lock);
}
return;
}
static unsigned int autofs4_need_mount(unsigned int flags)
{
unsigned int res = 0;
if (flags & (TRIGGER_FLAGS | TRIGGER_INTENTS))
res = 1;
return res;
}
static int autofs4_dir_open(struct inode *inode, struct file *file)
{
struct dentry *dentry = file->f_path.dentry;
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
DPRINTK("file=%p dentry=%p %.*s",
file, dentry, dentry->d_name.len, dentry->d_name.name);
if (autofs4_oz_mode(sbi))
goto out;
/*
* An empty directory in an autofs file system is always a
* mount point. The daemon must have failed to mount this
* during lookup so it doesn't exist. This can happen, for
* example, if user space returns an incorrect status for a
* mount request. Otherwise we're doing a readdir on the
* autofs file system so just let the libfs routines handle
* it.
*/
spin_lock(&dcache_lock);
if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
spin_unlock(&dcache_lock);
return -ENOENT;
}
spin_unlock(&dcache_lock);
out:
return dcache_dir_open(inode, file);
}
static int try_to_fill_dentry(struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
int status;
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
*/
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);
/* Update expiry counter */
ino->last_used = jiffies;
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);
/*
* For an expire of a covered direct or offset mount we need
* to break out of follow_down() at the autofs mount trigger
* (d_mounted--), so we can see the expiring flag, and manage
* the blocking and following here until the expire is completed.
*/
if (oz_mode) {
spin_lock(&sbi->fs_lock);
if (ino->flags & AUTOFS_INF_EXPIRING) {
spin_unlock(&sbi->fs_lock);
/* Follow down to our covering mount. */
if (!follow_down(&nd->path))
goto done;
goto follow;
}
spin_unlock(&sbi->fs_lock);
goto done;
}
/* If an expire request is pending everyone must wait. */
autofs4_expire_wait(dentry);
/* We trigger a mount for almost all flags */
lookup_type = autofs4_need_mount(nd->flags);
spin_lock(&sbi->fs_lock);
spin_lock(&dcache_lock);
if (!(lookup_type || ino->flags & AUTOFS_INF_PENDING)) {
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
goto follow;
}
/*
* 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.
*/
if (ino->flags & AUTOFS_INF_PENDING ||
(!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs))) {
ino->flags |= AUTOFS_INF_PENDING;
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
status = try_to_fill_dentry(dentry);
spin_lock(&sbi->fs_lock);
ino->flags &= ~AUTOFS_INF_PENDING;
spin_unlock(&sbi->fs_lock);
if (status)
goto out_error;
goto follow;
}
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
follow:
/*
* If there is no root mount it must be an autofs
* multi-mount with no root offset so we don't need
* to follow it.
*/
if (d_mountpoint(dentry)) {
if (!autofs4_follow_mount(&nd->path)) {
status = -ENOENT;
goto out_error;
}
}
done:
return NULL;
out_error:
path_put(&nd->path);
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);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
struct rehash_entry *entry;
int flags = nd ? nd->flags : 0;
unsigned int mutex_aquired;
DPRINTK("name = %.*s oz_mode = %d",
dentry->d_name.len, dentry->d_name.name, oz_mode);
/* Daemon never causes a mount to trigger */
if (autofs4_oz_mode(sbi))
return 1;
entry = kmalloc(sizeof(struct rehash_entry), GFP_KERNEL);
if (!entry)
return -ENOMEM;
mutex_aquired = mutex_trylock(&dir->i_mutex);
spin_lock(&sbi->fs_lock);
spin_lock(&dcache_lock);
/* Pending dentry */
if (autofs4_ispending(dentry)) {
int status;
/*
* We can only unhash and send this to ->lookup() if
* the directory mutex is held over d_revalidate() and
* ->lookup(). This prevents the VFS from incorrectly
* seeing the dentry as non-existent.
*/
ino->flags |= AUTOFS_INF_PENDING;
if (!mutex_aquired) {
autofs4_revalidate_drop(dentry, entry);
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
return 0;
}
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
mutex_unlock(&dir->i_mutex);
kfree(entry);
/*
* If the directory has gone away due to an expire
* we have been called as ->d_revalidate() and so
* we need to return false and proceed to ->lookup().
*/
if (autofs4_expire_wait(dentry) == -EAGAIN)
return 0;
/*
* A zero status is success otherwise we have a
* negative error code.
*/
status = try_to_fill_dentry(dentry);
spin_lock(&sbi->fs_lock);
ino->flags &= ~AUTOFS_INF_PENDING;
spin_unlock(&sbi->fs_lock);
if (status == 0)
return 1;
return status;
}
/* Check for a non-mountpoint directory with no contents */
if (S_ISDIR(dentry->d_inode->i_mode) &&
!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
DPRINTK("dentry=%p %.*s, emptydir",
dentry, dentry->d_name.len, dentry->d_name.name);
if (autofs4_need_mount(flags) || current->link_count) {
int status;
/*
* We can only unhash and send this to ->lookup() if
* the directory mutex is held over d_revalidate() and
* ->lookup(). This prevents the VFS from incorrectly
* seeing the dentry as non-existent.
*/
ino->flags |= AUTOFS_INF_PENDING;
if (!mutex_aquired) {
autofs4_revalidate_drop(dentry, entry);
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
return 0;
}
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
mutex_unlock(&dir->i_mutex);
kfree(entry);
/*
* A zero status is success otherwise we have a
* negative error code.
*/
status = try_to_fill_dentry(dentry);
spin_lock(&sbi->fs_lock);
ino->flags &= ~AUTOFS_INF_PENDING;
spin_unlock(&sbi->fs_lock);
if (status == 0)
return 1;
return status;
}
}
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
if (mutex_aquired)
mutex_unlock(&dir->i_mutex);
kfree(entry);
return 1;
}
static void autofs4_free_rehash_entrys(struct autofs_info *inf)
{
struct list_head *head = &inf->rehash_list;
struct rehash_entry *entry, *next;
list_for_each_entry_safe(entry, next, head, list) {
list_del(&entry->list);
kfree(entry);
}
}
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) {
struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
if (sbi) {
spin_lock(&sbi->lookup_lock);
if (!list_empty(&inf->active))
list_del(&inf->active);
if (!list_empty(&inf->expiring))
list_del(&inf->expiring);
if (!list_empty(&inf->rehash_list))
autofs4_free_rehash_entrys(inf);
spin_unlock(&sbi->lookup_lock);
}
inf->dentry = NULL;
inf->inode = NULL;
autofs4_free_ino(inf);
}
}
/* For dentries of directories in the root dir */
static const struct dentry_operations autofs4_root_dentry_operations = {
.d_revalidate = autofs4_revalidate,
.d_release = autofs4_dentry_release,
};
/* For other dentries */
static const struct dentry_operations autofs4_dentry_operations = {
.d_revalidate = autofs4_revalidate,
.d_release = autofs4_dentry_release,
};
static struct dentry *autofs4_lookup_active(struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct dentry *parent = dentry->d_parent;
struct qstr *name = &dentry->d_name;
unsigned int len = name->len;
unsigned int hash = name->hash;
const unsigned char *str = name->name;
struct list_head *p, *head;
restart:
spin_lock(&dcache_lock);
spin_lock(&sbi->lookup_lock);
head = &sbi->active_list;
list_for_each(p, head) {
struct autofs_info *ino;
struct dentry *active;
struct qstr *qstr;
ino = list_entry(p, struct autofs_info, active);
active = ino->dentry;
spin_lock(&active->d_lock);
/* Already gone? */
if (atomic_read(&active->d_count) == 0)
goto next;
if (active->d_inode && IS_DEADDIR(active->d_inode)) {
if (!list_empty(&ino->rehash_list)) {
dget(active);
spin_unlock(&active->d_lock);
spin_unlock(&sbi->lookup_lock);
spin_unlock(&dcache_lock);
autofs4_remove_rehash_entrys(ino);
dput(active);
goto restart;
}
goto next;
}
qstr = &active->d_name;
if (active->d_name.hash != hash)
goto next;
if (active->d_parent != parent)
goto next;
if (qstr->len != len)
goto next;
if (memcmp(qstr->name, str, len))
goto next;
dget(active);
spin_unlock(&active->d_lock);
spin_unlock(&sbi->lookup_lock);
spin_unlock(&dcache_lock);
return active;
next:
spin_unlock(&active->d_lock);
}
spin_unlock(&sbi->lookup_lock);
spin_unlock(&dcache_lock);
return NULL;
}
static struct dentry *autofs4_lookup_expiring(struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct dentry *parent = dentry->d_parent;
struct qstr *name = &dentry->d_name;
unsigned int len = name->len;
unsigned int hash = name->hash;
const unsigned char *str = name->name;
struct list_head *p, *head;
spin_lock(&dcache_lock);
spin_lock(&sbi->lookup_lock);
head = &sbi->expiring_list;
list_for_each(p, head) {
struct autofs_info *ino;
struct dentry *expiring;
struct qstr *qstr;
ino = list_entry(p, struct autofs_info, expiring);
expiring = ino->dentry;
spin_lock(&expiring->d_lock);
/* Bad luck, we've already been dentry_iput */
if (!expiring->d_inode)
goto next;
qstr = &expiring->d_name;
if (expiring->d_name.hash != hash)
goto next;
if (expiring->d_parent != parent)
goto next;
if (qstr->len != len)
goto next;
if (memcmp(qstr->name, str, len))
goto next;
dget(expiring);
spin_unlock(&expiring->d_lock);
spin_unlock(&sbi->lookup_lock);
spin_unlock(&dcache_lock);
return expiring;
next:
spin_unlock(&expiring->d_lock);
}
spin_unlock(&sbi->lookup_lock);
spin_unlock(&dcache_lock);
return NULL;
}
static struct autofs_info *init_new_dentry(struct autofs_sb_info *sbi,
struct dentry *dentry, int oz_mode)
{
struct autofs_info *ino;
/*
* Mark the dentry incomplete but don't hash it. We do this
* to serialize our inode creation operations (symlink and
* mkdir) which prevents deadlock during the callback to
* the daemon. Subsequent user space lookups for the same
* dentry are placed on the wait queue while the daemon
* itself is allowed passage unresticted so the create
* operation itself can then hash the dentry. Finally,
* we check for the hashed dentry and return the newly
* hashed dentry.
*/
dentry->d_op = &autofs4_root_dentry_operations;
/*
* And we need to ensure that the same dentry is used for
* all following lookup calls until it is hashed so that
* the dentry flags are persistent throughout the request.
*/
ino = autofs4_init_ino(NULL, sbi, 0555);
if (!ino)
return ERR_PTR(-ENOMEM);
dentry->d_fsdata = ino;
ino->dentry = dentry;
/*
* Only set the mount pending flag for new dentrys not created
* by the daemon.
*/
if (!oz_mode)
ino->flags |= AUTOFS_INF_PENDING;
d_instantiate(dentry, NULL);
return ino;
}
/* Lookups in the root directory */
static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
struct autofs_sb_info *sbi;
struct autofs_info *ino;
struct dentry *expiring, *active;
int oz_mode;
int status = 0;
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, task_pgrp_nr(current), sbi->catatonic, oz_mode);
spin_lock(&sbi->fs_lock);
active = autofs4_lookup_active(dentry);
if (active) {
dentry = active;
ino = autofs4_dentry_ino(dentry);
/* If this came from revalidate, rehash it */
autofs4_revalidate_rehash(dentry);
spin_unlock(&sbi->fs_lock);
} else {
spin_unlock(&sbi->fs_lock);
ino = init_new_dentry(sbi, dentry, oz_mode);
if (IS_ERR(ino))
return (struct dentry *) ino;
}
autofs4_add_active(dentry);
if (!oz_mode) {
expiring = autofs4_lookup_expiring(dentry);
mutex_unlock(&dir->i_mutex);
if (expiring) {
/*
* If we are racing with expire the request might not
* be quite complete but the directory has been removed
* so it must have been successful, so just wait for it.
*/
autofs4_expire_wait(expiring);
dput(expiring);
}
status = try_to_fill_dentry(dentry);
mutex_lock(&dir->i_mutex);
spin_lock(&sbi->fs_lock);
ino->flags &= ~AUTOFS_INF_PENDING;
spin_unlock(&sbi->fs_lock);
}
autofs4_del_active(dentry);
/*
* If we had a mount fail, check if we had to handle
* a signal. If so we can force a restart..
*/
if (status) {
/* See if we were interrupted */
if (signal_pending(current)) {
sigset_t *sigset = ¤t->pending.signal;
if (sigismember (sigset, SIGKILL) ||
sigismember (sigset, SIGQUIT) ||
sigismember (sigset, SIGINT)) {
if (active)
dput(active);
return ERR_PTR(-ERESTARTNOINTR);
}
}
}
/*
* User space can (and has done in the past) remove and re-create
* this directory during the callback. This can leave us with an
* unhashed dentry, but a successful mount! So we need to
* perform another cached lookup in case the dentry now exists.
*/
if (!oz_mode && !have_submounts(dentry)) {
struct dentry *new;
new = d_lookup(dentry->d_parent, &dentry->d_name);
if (new) {
if (active)
dput(active);
return new;
} else {
if (!status)
status = -ENOENT;
}
}
/*
* If we had a mount failure, return status to user space.
* If the mount succeeded and we used a dentry from the active queue
* return it.
*/
if (status) {
dentry = ERR_PTR(status);
if (active)
dput(active);
return dentry;
} else {
/*
* Valid successful mount, return active dentry or NULL
* for a new dentry.
*/
if (active)
return active;
}
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)
return -ENOMEM;
ino->size = strlen(symname);
cp = kmalloc(ino->size + 1, GFP_KERNEL);
if (!cp) {
if (!dentry->d_fsdata)
kfree(ino);
return -ENOMEM;
}
strcpy(cp, symname);
inode = autofs4_get_inode(dir->i_sb, ino);
if (!inode) {
kfree(cp);
if (!dentry->d_fsdata)
kfree(ino);
return -ENOMEM;
}
d_add(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;
ino->u.symlink = cp;
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 the unlink is probably the result of an expire.
* We simply d_drop it and add it to a expiring list in the super block,
* which allows the dentry lookup to check for an incomplete expire.
*
* 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;
clear_nlink(dentry->d_inode);
dir->i_mtime = CURRENT_TIME;
spin_lock(&dcache_lock);
spin_lock(&dentry->d_lock);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
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;
DPRINTK("dentry %p, removing %.*s",
dentry, dentry->d_name.len, dentry->d_name.name);
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;
clear_nlink(dentry->d_inode);
if (dir->i_nlink)
drop_nlink(dir);
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)
return -ENOMEM;
inode = autofs4_get_inode(dir->i_sb, ino);
if (!inode) {
if (!dentry->d_fsdata)
kfree(ino);
return -ENOMEM;
}
d_add(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;
inc_nlink(dir);
dir->i_mtime = CURRENT_TIME;
return 0;
}