linux/fs/inotify.c
John McCutchan 7c657f2f25 [PATCH] Document idr_get_new_above() semantics, update inotify
There is an off by one problem with idr_get_new_above.

The comment and function name suggest that it will return an id >
starting_id, but it actually returned an id >= starting_id, and kernel
callers other than inotify treated it as such.

The patch below fixes the comment, and fixes inotifys usage.  The
function name still doesn't match the behaviour, but it never did.

Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-08-26 11:32:57 -07:00

1058 lines
26 KiB
C

/*
* fs/inotify.c - inode-based file event notifications
*
* Authors:
* John McCutchan <ttb@tentacle.dhs.org>
* Robert Love <rml@novell.com>
*
* Copyright (C) 2005 John McCutchan
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/writeback.h>
#include <linux/inotify.h>
#include <asm/ioctls.h>
static atomic_t inotify_cookie;
static kmem_cache_t *watch_cachep;
static kmem_cache_t *event_cachep;
static struct vfsmount *inotify_mnt;
/* these are configurable via /proc/sys/fs/inotify/ */
int inotify_max_user_instances;
int inotify_max_user_watches;
int inotify_max_queued_events;
/*
* Lock ordering:
*
* dentry->d_lock (used to keep d_move() away from dentry->d_parent)
* iprune_sem (synchronize shrink_icache_memory())
* inode_lock (protects the super_block->s_inodes list)
* inode->inotify_sem (protects inode->inotify_watches and watches->i_list)
* inotify_dev->sem (protects inotify_device and watches->d_list)
*/
/*
* Lifetimes of the three main data structures--inotify_device, inode, and
* inotify_watch--are managed by reference count.
*
* inotify_device: Lifetime is from inotify_init() until release. Additional
* references can bump the count via get_inotify_dev() and drop the count via
* put_inotify_dev().
*
* inotify_watch: Lifetime is from create_watch() to destory_watch().
* Additional references can bump the count via get_inotify_watch() and drop
* the count via put_inotify_watch().
*
* inode: Pinned so long as the inode is associated with a watch, from
* create_watch() to put_inotify_watch().
*/
/*
* struct inotify_device - represents an inotify instance
*
* This structure is protected by the semaphore 'sem'.
*/
struct inotify_device {
wait_queue_head_t wq; /* wait queue for i/o */
struct idr idr; /* idr mapping wd -> watch */
struct semaphore sem; /* protects this bad boy */
struct list_head events; /* list of queued events */
struct list_head watches; /* list of watches */
atomic_t count; /* reference count */
struct user_struct *user; /* user who opened this dev */
unsigned int queue_size; /* size of the queue (bytes) */
unsigned int event_count; /* number of pending events */
unsigned int max_events; /* maximum number of events */
u32 last_wd; /* the last wd allocated */
};
/*
* struct inotify_kernel_event - An inotify event, originating from a watch and
* queued for user-space. A list of these is attached to each instance of the
* device. In read(), this list is walked and all events that can fit in the
* buffer are returned.
*
* Protected by dev->sem of the device in which we are queued.
*/
struct inotify_kernel_event {
struct inotify_event event; /* the user-space event */
struct list_head list; /* entry in inotify_device's list */
char *name; /* filename, if any */
};
/*
* struct inotify_watch - represents a watch request on a specific inode
*
* d_list is protected by dev->sem of the associated watch->dev.
* i_list and mask are protected by inode->inotify_sem of the associated inode.
* dev, inode, and wd are never written to once the watch is created.
*/
struct inotify_watch {
struct list_head d_list; /* entry in inotify_device's list */
struct list_head i_list; /* entry in inode's list */
atomic_t count; /* reference count */
struct inotify_device *dev; /* associated device */
struct inode *inode; /* associated inode */
s32 wd; /* watch descriptor */
u32 mask; /* event mask for this watch */
};
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
static int zero;
ctl_table inotify_table[] = {
{
.ctl_name = INOTIFY_MAX_USER_INSTANCES,
.procname = "max_user_instances",
.data = &inotify_max_user_instances,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &zero,
},
{
.ctl_name = INOTIFY_MAX_USER_WATCHES,
.procname = "max_user_watches",
.data = &inotify_max_user_watches,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &zero,
},
{
.ctl_name = INOTIFY_MAX_QUEUED_EVENTS,
.procname = "max_queued_events",
.data = &inotify_max_queued_events,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &zero
},
{ .ctl_name = 0 }
};
#endif /* CONFIG_SYSCTL */
static inline void get_inotify_dev(struct inotify_device *dev)
{
atomic_inc(&dev->count);
}
static inline void put_inotify_dev(struct inotify_device *dev)
{
if (atomic_dec_and_test(&dev->count)) {
atomic_dec(&dev->user->inotify_devs);
free_uid(dev->user);
kfree(dev);
}
}
static inline void get_inotify_watch(struct inotify_watch *watch)
{
atomic_inc(&watch->count);
}
/*
* put_inotify_watch - decrements the ref count on a given watch. cleans up
* the watch and its references if the count reaches zero.
*/
static inline void put_inotify_watch(struct inotify_watch *watch)
{
if (atomic_dec_and_test(&watch->count)) {
put_inotify_dev(watch->dev);
iput(watch->inode);
kmem_cache_free(watch_cachep, watch);
}
}
/*
* kernel_event - create a new kernel event with the given parameters
*
* This function can sleep.
*/
static struct inotify_kernel_event * kernel_event(s32 wd, u32 mask, u32 cookie,
const char *name)
{
struct inotify_kernel_event *kevent;
kevent = kmem_cache_alloc(event_cachep, GFP_KERNEL);
if (unlikely(!kevent))
return NULL;
/* we hand this out to user-space, so zero it just in case */
memset(&kevent->event, 0, sizeof(struct inotify_event));
kevent->event.wd = wd;
kevent->event.mask = mask;
kevent->event.cookie = cookie;
INIT_LIST_HEAD(&kevent->list);
if (name) {
size_t len, rem, event_size = sizeof(struct inotify_event);
/*
* We need to pad the filename so as to properly align an
* array of inotify_event structures. Because the structure is
* small and the common case is a small filename, we just round
* up to the next multiple of the structure's sizeof. This is
* simple and safe for all architectures.
*/
len = strlen(name) + 1;
rem = event_size - len;
if (len > event_size) {
rem = event_size - (len % event_size);
if (len % event_size == 0)
rem = 0;
}
kevent->name = kmalloc(len + rem, GFP_KERNEL);
if (unlikely(!kevent->name)) {
kmem_cache_free(event_cachep, kevent);
return NULL;
}
memcpy(kevent->name, name, len);
if (rem)
memset(kevent->name + len, 0, rem);
kevent->event.len = len + rem;
} else {
kevent->event.len = 0;
kevent->name = NULL;
}
return kevent;
}
/*
* inotify_dev_get_event - return the next event in the given dev's queue
*
* Caller must hold dev->sem.
*/
static inline struct inotify_kernel_event *
inotify_dev_get_event(struct inotify_device *dev)
{
return list_entry(dev->events.next, struct inotify_kernel_event, list);
}
/*
* inotify_dev_queue_event - add a new event to the given device
*
* Caller must hold dev->sem. Can sleep (calls kernel_event()).
*/
static void inotify_dev_queue_event(struct inotify_device *dev,
struct inotify_watch *watch, u32 mask,
u32 cookie, const char *name)
{
struct inotify_kernel_event *kevent, *last;
/* coalescing: drop this event if it is a dupe of the previous */
last = inotify_dev_get_event(dev);
if (last && last->event.mask == mask && last->event.wd == watch->wd &&
last->event.cookie == cookie) {
const char *lastname = last->name;
if (!name && !lastname)
return;
if (name && lastname && !strcmp(lastname, name))
return;
}
/* the queue overflowed and we already sent the Q_OVERFLOW event */
if (unlikely(dev->event_count > dev->max_events))
return;
/* if the queue overflows, we need to notify user space */
if (unlikely(dev->event_count == dev->max_events))
kevent = kernel_event(-1, IN_Q_OVERFLOW, cookie, NULL);
else
kevent = kernel_event(watch->wd, mask, cookie, name);
if (unlikely(!kevent))
return;
/* queue the event and wake up anyone waiting */
dev->event_count++;
dev->queue_size += sizeof(struct inotify_event) + kevent->event.len;
list_add_tail(&kevent->list, &dev->events);
wake_up_interruptible(&dev->wq);
}
/*
* remove_kevent - cleans up and ultimately frees the given kevent
*
* Caller must hold dev->sem.
*/
static void remove_kevent(struct inotify_device *dev,
struct inotify_kernel_event *kevent)
{
list_del(&kevent->list);
dev->event_count--;
dev->queue_size -= sizeof(struct inotify_event) + kevent->event.len;
kfree(kevent->name);
kmem_cache_free(event_cachep, kevent);
}
/*
* inotify_dev_event_dequeue - destroy an event on the given device
*
* Caller must hold dev->sem.
*/
static void inotify_dev_event_dequeue(struct inotify_device *dev)
{
if (!list_empty(&dev->events)) {
struct inotify_kernel_event *kevent;
kevent = inotify_dev_get_event(dev);
remove_kevent(dev, kevent);
}
}
/*
* inotify_dev_get_wd - returns the next WD for use by the given dev
*
* Callers must hold dev->sem. This function can sleep.
*/
static int inotify_dev_get_wd(struct inotify_device *dev,
struct inotify_watch *watch)
{
int ret;
do {
if (unlikely(!idr_pre_get(&dev->idr, GFP_KERNEL)))
return -ENOSPC;
ret = idr_get_new_above(&dev->idr, watch, dev->last_wd+1, &watch->wd);
} while (ret == -EAGAIN);
return ret;
}
/*
* find_inode - resolve a user-given path to a specific inode and return a nd
*/
static int find_inode(const char __user *dirname, struct nameidata *nd)
{
int error;
error = __user_walk(dirname, LOOKUP_FOLLOW, nd);
if (error)
return error;
/* you can only watch an inode if you have read permissions on it */
error = permission(nd->dentry->d_inode, MAY_READ, NULL);
if (error)
path_release(nd);
return error;
}
/*
* create_watch - creates a watch on the given device.
*
* Callers must hold dev->sem. Calls inotify_dev_get_wd() so may sleep.
* Both 'dev' and 'inode' (by way of nameidata) need to be pinned.
*/
static struct inotify_watch *create_watch(struct inotify_device *dev,
u32 mask, struct inode *inode)
{
struct inotify_watch *watch;
int ret;
if (atomic_read(&dev->user->inotify_watches) >=
inotify_max_user_watches)
return ERR_PTR(-ENOSPC);
watch = kmem_cache_alloc(watch_cachep, GFP_KERNEL);
if (unlikely(!watch))
return ERR_PTR(-ENOMEM);
ret = inotify_dev_get_wd(dev, watch);
if (unlikely(ret)) {
kmem_cache_free(watch_cachep, watch);
return ERR_PTR(ret);
}
dev->last_wd = watch->wd;
watch->mask = mask;
atomic_set(&watch->count, 0);
INIT_LIST_HEAD(&watch->d_list);
INIT_LIST_HEAD(&watch->i_list);
/* save a reference to device and bump the count to make it official */
get_inotify_dev(dev);
watch->dev = dev;
/*
* Save a reference to the inode and bump the ref count to make it
* official. We hold a reference to nameidata, which makes this safe.
*/
watch->inode = igrab(inode);
/* bump our own count, corresponding to our entry in dev->watches */
get_inotify_watch(watch);
atomic_inc(&dev->user->inotify_watches);
return watch;
}
/*
* inotify_find_dev - find the watch associated with the given inode and dev
*
* Callers must hold inode->inotify_sem.
*/
static struct inotify_watch *inode_find_dev(struct inode *inode,
struct inotify_device *dev)
{
struct inotify_watch *watch;
list_for_each_entry(watch, &inode->inotify_watches, i_list) {
if (watch->dev == dev)
return watch;
}
return NULL;
}
/*
* remove_watch_no_event - remove_watch() without the IN_IGNORED event.
*/
static void remove_watch_no_event(struct inotify_watch *watch,
struct inotify_device *dev)
{
list_del(&watch->i_list);
list_del(&watch->d_list);
atomic_dec(&dev->user->inotify_watches);
idr_remove(&dev->idr, watch->wd);
put_inotify_watch(watch);
}
/*
* remove_watch - Remove a watch from both the device and the inode. Sends
* the IN_IGNORED event to the given device signifying that the inode is no
* longer watched.
*
* Callers must hold both inode->inotify_sem and dev->sem. We drop a
* reference to the inode before returning.
*
* The inode is not iput() so as to remain atomic. If the inode needs to be
* iput(), the call returns one. Otherwise, it returns zero.
*/
static void remove_watch(struct inotify_watch *watch,struct inotify_device *dev)
{
inotify_dev_queue_event(dev, watch, IN_IGNORED, 0, NULL);
remove_watch_no_event(watch, dev);
}
/*
* inotify_inode_watched - returns nonzero if there are watches on this inode
* and zero otherwise. We call this lockless, we do not care if we race.
*/
static inline int inotify_inode_watched(struct inode *inode)
{
return !list_empty(&inode->inotify_watches);
}
/* Kernel API */
/**
* inotify_inode_queue_event - queue an event to all watches on this inode
* @inode: inode event is originating from
* @mask: event mask describing this event
* @cookie: cookie for synchronization, or zero
* @name: filename, if any
*/
void inotify_inode_queue_event(struct inode *inode, u32 mask, u32 cookie,
const char *name)
{
struct inotify_watch *watch, *next;
if (!inotify_inode_watched(inode))
return;
down(&inode->inotify_sem);
list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) {
u32 watch_mask = watch->mask;
if (watch_mask & mask) {
struct inotify_device *dev = watch->dev;
get_inotify_watch(watch);
down(&dev->sem);
inotify_dev_queue_event(dev, watch, mask, cookie, name);
if (watch_mask & IN_ONESHOT)
remove_watch_no_event(watch, dev);
up(&dev->sem);
put_inotify_watch(watch);
}
}
up(&inode->inotify_sem);
}
EXPORT_SYMBOL_GPL(inotify_inode_queue_event);
/**
* inotify_dentry_parent_queue_event - queue an event to a dentry's parent
* @dentry: the dentry in question, we queue against this dentry's parent
* @mask: event mask describing this event
* @cookie: cookie for synchronization, or zero
* @name: filename, if any
*/
void inotify_dentry_parent_queue_event(struct dentry *dentry, u32 mask,
u32 cookie, const char *name)
{
struct dentry *parent;
struct inode *inode;
spin_lock(&dentry->d_lock);
parent = dentry->d_parent;
inode = parent->d_inode;
if (inotify_inode_watched(inode)) {
dget(parent);
spin_unlock(&dentry->d_lock);
inotify_inode_queue_event(inode, mask, cookie, name);
dput(parent);
} else
spin_unlock(&dentry->d_lock);
}
EXPORT_SYMBOL_GPL(inotify_dentry_parent_queue_event);
/**
* inotify_get_cookie - return a unique cookie for use in synchronizing events.
*/
u32 inotify_get_cookie(void)
{
return atomic_inc_return(&inotify_cookie);
}
EXPORT_SYMBOL_GPL(inotify_get_cookie);
/**
* inotify_unmount_inodes - an sb is unmounting. handle any watched inodes.
* @list: list of inodes being unmounted (sb->s_inodes)
*
* Called with inode_lock held, protecting the unmounting super block's list
* of inodes, and with iprune_sem held, keeping shrink_icache_memory() at bay.
* We temporarily drop inode_lock, however, and CAN block.
*/
void inotify_unmount_inodes(struct list_head *list)
{
struct inode *inode, *next_i, *need_iput = NULL;
list_for_each_entry_safe(inode, next_i, list, i_sb_list) {
struct inotify_watch *watch, *next_w;
struct inode *need_iput_tmp;
struct list_head *watches;
/*
* If i_count is zero, the inode cannot have any watches and
* doing an __iget/iput with MS_ACTIVE clear would actually
* evict all inodes with zero i_count from icache which is
* unnecessarily violent and may in fact be illegal to do.
*/
if (!atomic_read(&inode->i_count))
continue;
/*
* We cannot __iget() an inode in state I_CLEAR, I_FREEING, or
* I_WILL_FREE which is fine because by that point the inode
* cannot have any associated watches.
*/
if (inode->i_state & (I_CLEAR | I_FREEING | I_WILL_FREE))
continue;
need_iput_tmp = need_iput;
need_iput = NULL;
/* In case the remove_watch() drops a reference. */
if (inode != need_iput_tmp)
__iget(inode);
else
need_iput_tmp = NULL;
/* In case the dropping of a reference would nuke next_i. */
if ((&next_i->i_sb_list != list) &&
atomic_read(&next_i->i_count) &&
!(next_i->i_state & (I_CLEAR | I_FREEING |
I_WILL_FREE))) {
__iget(next_i);
need_iput = next_i;
}
/*
* We can safely drop inode_lock here because we hold
* references on both inode and next_i. Also no new inodes
* will be added since the umount has begun. Finally,
* iprune_sem keeps shrink_icache_memory() away.
*/
spin_unlock(&inode_lock);
if (need_iput_tmp)
iput(need_iput_tmp);
/* for each watch, send IN_UNMOUNT and then remove it */
down(&inode->inotify_sem);
watches = &inode->inotify_watches;
list_for_each_entry_safe(watch, next_w, watches, i_list) {
struct inotify_device *dev = watch->dev;
down(&dev->sem);
inotify_dev_queue_event(dev, watch, IN_UNMOUNT,0,NULL);
remove_watch(watch, dev);
up(&dev->sem);
}
up(&inode->inotify_sem);
iput(inode);
spin_lock(&inode_lock);
}
}
EXPORT_SYMBOL_GPL(inotify_unmount_inodes);
/**
* inotify_inode_is_dead - an inode has been deleted, cleanup any watches
* @inode: inode that is about to be removed
*/
void inotify_inode_is_dead(struct inode *inode)
{
struct inotify_watch *watch, *next;
down(&inode->inotify_sem);
list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) {
struct inotify_device *dev = watch->dev;
down(&dev->sem);
remove_watch(watch, dev);
up(&dev->sem);
}
up(&inode->inotify_sem);
}
EXPORT_SYMBOL_GPL(inotify_inode_is_dead);
/* Device Interface */
static unsigned int inotify_poll(struct file *file, poll_table *wait)
{
struct inotify_device *dev = file->private_data;
int ret = 0;
poll_wait(file, &dev->wq, wait);
down(&dev->sem);
if (!list_empty(&dev->events))
ret = POLLIN | POLLRDNORM;
up(&dev->sem);
return ret;
}
static ssize_t inotify_read(struct file *file, char __user *buf,
size_t count, loff_t *pos)
{
size_t event_size = sizeof (struct inotify_event);
struct inotify_device *dev;
char __user *start;
int ret;
DEFINE_WAIT(wait);
start = buf;
dev = file->private_data;
while (1) {
int events;
prepare_to_wait(&dev->wq, &wait, TASK_INTERRUPTIBLE);
down(&dev->sem);
events = !list_empty(&dev->events);
up(&dev->sem);
if (events) {
ret = 0;
break;
}
if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
break;
}
if (signal_pending(current)) {
ret = -EINTR;
break;
}
schedule();
}
finish_wait(&dev->wq, &wait);
if (ret)
return ret;
down(&dev->sem);
while (1) {
struct inotify_kernel_event *kevent;
ret = buf - start;
if (list_empty(&dev->events))
break;
kevent = inotify_dev_get_event(dev);
if (event_size + kevent->event.len > count)
break;
if (copy_to_user(buf, &kevent->event, event_size)) {
ret = -EFAULT;
break;
}
buf += event_size;
count -= event_size;
if (kevent->name) {
if (copy_to_user(buf, kevent->name, kevent->event.len)){
ret = -EFAULT;
break;
}
buf += kevent->event.len;
count -= kevent->event.len;
}
remove_kevent(dev, kevent);
}
up(&dev->sem);
return ret;
}
static int inotify_release(struct inode *ignored, struct file *file)
{
struct inotify_device *dev = file->private_data;
/*
* Destroy all of the watches on this device. Unfortunately, not very
* pretty. We cannot do a simple iteration over the list, because we
* do not know the inode until we iterate to the watch. But we need to
* hold inode->inotify_sem before dev->sem. The following works.
*/
while (1) {
struct inotify_watch *watch;
struct list_head *watches;
struct inode *inode;
down(&dev->sem);
watches = &dev->watches;
if (list_empty(watches)) {
up(&dev->sem);
break;
}
watch = list_entry(watches->next, struct inotify_watch, d_list);
get_inotify_watch(watch);
up(&dev->sem);
inode = watch->inode;
down(&inode->inotify_sem);
down(&dev->sem);
remove_watch_no_event(watch, dev);
up(&dev->sem);
up(&inode->inotify_sem);
put_inotify_watch(watch);
}
/* destroy all of the events on this device */
down(&dev->sem);
while (!list_empty(&dev->events))
inotify_dev_event_dequeue(dev);
up(&dev->sem);
/* free this device: the put matching the get in inotify_init() */
put_inotify_dev(dev);
return 0;
}
/*
* inotify_ignore - remove a given wd from this inotify instance.
*
* Can sleep.
*/
static int inotify_ignore(struct inotify_device *dev, s32 wd)
{
struct inotify_watch *watch;
struct inode *inode;
down(&dev->sem);
watch = idr_find(&dev->idr, wd);
if (unlikely(!watch)) {
up(&dev->sem);
return -EINVAL;
}
get_inotify_watch(watch);
inode = watch->inode;
up(&dev->sem);
down(&inode->inotify_sem);
down(&dev->sem);
/* make sure that we did not race */
watch = idr_find(&dev->idr, wd);
if (likely(watch))
remove_watch(watch, dev);
up(&dev->sem);
up(&inode->inotify_sem);
put_inotify_watch(watch);
return 0;
}
static long inotify_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct inotify_device *dev;
void __user *p;
int ret = -ENOTTY;
dev = file->private_data;
p = (void __user *) arg;
switch (cmd) {
case FIONREAD:
ret = put_user(dev->queue_size, (int __user *) p);
break;
}
return ret;
}
static struct file_operations inotify_fops = {
.poll = inotify_poll,
.read = inotify_read,
.release = inotify_release,
.unlocked_ioctl = inotify_ioctl,
.compat_ioctl = inotify_ioctl,
};
asmlinkage long sys_inotify_init(void)
{
struct inotify_device *dev;
struct user_struct *user;
struct file *filp;
int fd, ret;
fd = get_unused_fd();
if (fd < 0)
return fd;
filp = get_empty_filp();
if (!filp) {
ret = -ENFILE;
goto out_put_fd;
}
user = get_uid(current->user);
if (unlikely(atomic_read(&user->inotify_devs) >=
inotify_max_user_instances)) {
ret = -EMFILE;
goto out_free_uid;
}
dev = kmalloc(sizeof(struct inotify_device), GFP_KERNEL);
if (unlikely(!dev)) {
ret = -ENOMEM;
goto out_free_uid;
}
filp->f_op = &inotify_fops;
filp->f_vfsmnt = mntget(inotify_mnt);
filp->f_dentry = dget(inotify_mnt->mnt_root);
filp->f_mapping = filp->f_dentry->d_inode->i_mapping;
filp->f_mode = FMODE_READ;
filp->f_flags = O_RDONLY;
filp->private_data = dev;
idr_init(&dev->idr);
INIT_LIST_HEAD(&dev->events);
INIT_LIST_HEAD(&dev->watches);
init_waitqueue_head(&dev->wq);
sema_init(&dev->sem, 1);
dev->event_count = 0;
dev->queue_size = 0;
dev->max_events = inotify_max_queued_events;
dev->user = user;
dev->last_wd = 0;
atomic_set(&dev->count, 0);
get_inotify_dev(dev);
atomic_inc(&user->inotify_devs);
fd_install(fd, filp);
return fd;
out_free_uid:
free_uid(user);
put_filp(filp);
out_put_fd:
put_unused_fd(fd);
return ret;
}
asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask)
{
struct inotify_watch *watch, *old;
struct inode *inode;
struct inotify_device *dev;
struct nameidata nd;
struct file *filp;
int ret, fput_needed;
filp = fget_light(fd, &fput_needed);
if (unlikely(!filp))
return -EBADF;
/* verify that this is indeed an inotify instance */
if (unlikely(filp->f_op != &inotify_fops)) {
ret = -EINVAL;
goto fput_and_out;
}
ret = find_inode(path, &nd);
if (unlikely(ret))
goto fput_and_out;
/* inode held in place by reference to nd; dev by fget on fd */
inode = nd.dentry->d_inode;
dev = filp->private_data;
down(&inode->inotify_sem);
down(&dev->sem);
/* don't let user-space set invalid bits: we don't want flags set */
mask &= IN_ALL_EVENTS;
if (unlikely(!mask)) {
ret = -EINVAL;
goto out;
}
/*
* Handle the case of re-adding a watch on an (inode,dev) pair that we
* are already watching. We just update the mask and return its wd.
*/
old = inode_find_dev(inode, dev);
if (unlikely(old)) {
old->mask = mask;
ret = old->wd;
goto out;
}
watch = create_watch(dev, mask, inode);
if (unlikely(IS_ERR(watch))) {
ret = PTR_ERR(watch);
goto out;
}
/* Add the watch to the device's and the inode's list */
list_add(&watch->d_list, &dev->watches);
list_add(&watch->i_list, &inode->inotify_watches);
ret = watch->wd;
out:
up(&dev->sem);
up(&inode->inotify_sem);
path_release(&nd);
fput_and_out:
fput_light(filp, fput_needed);
return ret;
}
asmlinkage long sys_inotify_rm_watch(int fd, u32 wd)
{
struct file *filp;
struct inotify_device *dev;
int ret, fput_needed;
filp = fget_light(fd, &fput_needed);
if (unlikely(!filp))
return -EBADF;
/* verify that this is indeed an inotify instance */
if (unlikely(filp->f_op != &inotify_fops)) {
ret = -EINVAL;
goto out;
}
dev = filp->private_data;
ret = inotify_ignore(dev, wd);
out:
fput_light(filp, fput_needed);
return ret;
}
static struct super_block *
inotify_get_sb(struct file_system_type *fs_type, int flags,
const char *dev_name, void *data)
{
return get_sb_pseudo(fs_type, "inotify", NULL, 0xBAD1DEA);
}
static struct file_system_type inotify_fs_type = {
.name = "inotifyfs",
.get_sb = inotify_get_sb,
.kill_sb = kill_anon_super,
};
/*
* inotify_setup - Our initialization function. Note that we cannnot return
* error because we have compiled-in VFS hooks. So an (unlikely) failure here
* must result in panic().
*/
static int __init inotify_setup(void)
{
int ret;
ret = register_filesystem(&inotify_fs_type);
if (unlikely(ret))
panic("inotify: register_filesystem returned %d!\n", ret);
inotify_mnt = kern_mount(&inotify_fs_type);
if (IS_ERR(inotify_mnt))
panic("inotify: kern_mount ret %ld!\n", PTR_ERR(inotify_mnt));
inotify_max_queued_events = 16384;
inotify_max_user_instances = 128;
inotify_max_user_watches = 8192;
atomic_set(&inotify_cookie, 0);
watch_cachep = kmem_cache_create("inotify_watch_cache",
sizeof(struct inotify_watch),
0, SLAB_PANIC, NULL, NULL);
event_cachep = kmem_cache_create("inotify_event_cache",
sizeof(struct inotify_kernel_event),
0, SLAB_PANIC, NULL, NULL);
return 0;
}
module_init(inotify_setup);