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提交 2d9048e2 编写于 作者: A Amy Griffis 提交者： Al Viro
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[PATCH] inotify (1/5): split kernel API from userspace support 

The following series of patches introduces a kernel API for inotify,
making it possible for kernel modules to benefit from inotify's
mechanism for watching inodes.  With these patches, inotify will
maintain for each caller a list of watches (via an embedded struct
inotify_watch), where each inotify_watch is associated with a
corresponding struct inode.  The caller registers an event handler and
specifies for which filesystem events their event handler should be
called per inotify_watch.
Signed-off-by: NAmy Griffis <amy.griffis@hp.com>
Acked-by: NRobert Love <rml@novell.com>
Acked-by: NJohn McCutchan <john@johnmccutchan.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
上级 90204e0b
隐藏空白更改
内联 并排
Showing with 1046 addition and 721 deletion
fs/Kconfig
浏览文件 @ 2d9048e2
......@@ -393,18 +393,30 @@ config INOTIFY
bool "Inotify file change notification support"
default y
---help---
Say Y here to enable inotify support and the associated system
calls. Inotify is a file change notification system and a
replacement for dnotify. Inotify fixes numerous shortcomings in
dnotify and introduces several new features. It allows monitoring
of both files and directories via a single open fd. Other features
include multiple file events, one-shot support, and unmount
Say Y here to enable inotify support. Inotify is a file change
notification system and a replacement for dnotify. Inotify fixes
numerous shortcomings in dnotify and introduces several new features
including multiple file events, one-shot support, and unmount
notification.
For more information, see Documentation/filesystems/inotify.txt
If unsure, say Y.
config INOTIFY_USER
bool "Inotify support for userspace"
depends on INOTIFY
default y
---help---
Say Y here to enable inotify support for userspace, including the
associated system calls. Inotify allows monitoring of both files and
directories via a single open fd. Events are read from the file
descriptor, which is also select()- and poll()-able.
For more information, see Documentation/filesystems/inotify.txt
If unsure, say Y.
config QUOTA
bool "Quota support"
help
......
fs/Makefile
浏览文件 @ 2d9048e2
......@@ -13,6 +13,7 @@ obj-y := open.o read_write.o file_table.o buffer.o bio.o super.o \
ioprio.o pnode.o drop_caches.o splice.o sync.o
obj-$(CONFIG_INOTIFY) += inotify.o
obj-$(CONFIG_INOTIFY_USER) += inotify_user.o
obj-$(CONFIG_EPOLL) += eventpoll.o
obj-$(CONFIG_COMPAT) += compat.o compat_ioctl.o
......
fs/inotify.c
浏览文件 @ 2d9048e2
......@@ -5,7 +5,10 @@
* John McCutchan <ttb@tentacle.dhs.org>
* Robert Love <rml@novell.com>
*
* Kernel API added by: Amy Griffis <amy.griffis@hp.com>
*
* Copyright (C) 2005 John McCutchan
* Copyright 2006 Hewlett-Packard Development Company, L.P.
*
* 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
......@@ -20,35 +23,17 @@
#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 <linux/syscalls.h>
#include <asm/ioctls.h>
static atomic_t inotify_cookie;
static kmem_cache_t *watch_cachep __read_mostly;
static kmem_cache_t *event_cachep __read_mostly;
static struct vfsmount *inotify_mnt __read_mostly;
/* these are configurable via /proc/sys/fs/inotify/ */
int inotify_max_user_instances __read_mostly;
int inotify_max_user_watches __read_mostly;
int inotify_max_queued_events __read_mostly;
/*
* Lock ordering:
*
......@@ -56,327 +41,108 @@ int inotify_max_queued_events __read_mostly;
* iprune_mutex (synchronize shrink_icache_memory())
* inode_lock (protects the super_block->s_inodes list)
* inode->inotify_mutex (protects inode->inotify_watches and watches->i_list)
* inotify_dev->mutex (protects inotify_device and watches->d_list)
* inotify_handle->mutex (protects inotify_handle and watches->h_list)
*
* The inode->inotify_mutex and inotify_handle->mutex and held during execution
* of a caller's event handler. Thus, the caller must not hold any locks
* taken in their event handler while calling any of the published inotify
* interfaces.
*/
/*
* Lifetimes of the three main data structures--inotify_device, inode, and
* Lifetimes of the three main data structures--inotify_handle, 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_handle: Lifetime is from inotify_init() to inotify_destroy().
* Additional references can bump the count via get_inotify_handle() and drop
* the count via put_inotify_handle().
*
* 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().
* inotify_watch: for inotify's purposes, lifetime is from inotify_add_watch()
* to remove_watch_no_event(). Additional references can bump the count via
* get_inotify_watch() and drop the count via put_inotify_watch(). The caller
* is reponsible for the final put after receiving IN_IGNORED, or when using
* IN_ONESHOT after receiving the first event. Inotify does the final put if
* inotify_destroy() is called.
*
* inode: Pinned so long as the inode is associated with a watch, from
* create_watch() to put_inotify_watch().
* inotify_add_watch() to the final put_inotify_watch().
*/
/*
* struct inotify_device - represents an inotify instance
* struct inotify_handle - represents an inotify instance
*
* This structure is protected by the mutex 'mutex'.
*/
struct inotify_device {
wait_queue_head_t wq; /* wait queue for i/o */
struct inotify_handle {
struct idr idr; /* idr mapping wd -> watch */
struct mutex mutex; /* 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 */
const struct inotify_operations *in_ops; /* inotify caller operations */
};
/*
* 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->mutex 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->mutex of the associated watch->dev.
* i_list and mask are protected by inode->inotify_mutex 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)
static inline void get_inotify_handle(struct inotify_handle *ih)
{
atomic_inc(&dev->count);
atomic_inc(&ih->count);
}
static inline void put_inotify_dev(struct inotify_device *dev)
static inline void put_inotify_handle(struct inotify_handle *ih)
{
if (atomic_dec_and_test(&dev->count)) {
atomic_dec(&dev->user->inotify_devs);
free_uid(dev->user);
idr_destroy(&dev->idr);
kfree(dev);
if (atomic_dec_and_test(&ih->count)) {
idr_destroy(&ih->idr);
kfree(ih);
}
}
static inline void get_inotify_watch(struct inotify_watch *watch)
/**
* get_inotify_watch - grab a reference to an inotify_watch
* @watch: watch to grab
*/
void get_inotify_watch(struct inotify_watch *watch)
{
atomic_inc(&watch->count);
}
EXPORT_SYMBOL_GPL(get_inotify_watch);
/*
/**
* put_inotify_watch - decrements the ref count on a given watch. cleans up
* the watch and its references if the count reaches zero.
* watch references if the count reaches zero. inotify_watch is freed by
* inotify callers via the destroy_watch() op.
* @watch: watch to release
*/
static inline void put_inotify_watch(struct inotify_watch *watch)
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->mutex.
*/
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->mutex. 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->mutex.
*/
static void remove_kevent(struct inotify_device *dev,
struct inotify_kernel_event *kevent)
{
list_del(&kevent->list);
struct inotify_handle *ih = watch->ih;
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->mutex.
*/
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);
iput(watch->inode);
ih->in_ops->destroy_watch(watch);
put_inotify_handle(ih);
}
}
EXPORT_SYMBOL_GPL(put_inotify_watch);
/*
* inotify_dev_get_wd - returns the next WD for use by the given dev
* inotify_handle_get_wd - returns the next WD for use by the given handle
*
* Callers must hold dev->mutex. This function can sleep.
* Callers must hold ih->mutex. This function can sleep.
*/
static int inotify_dev_get_wd(struct inotify_device *dev,
struct inotify_watch *watch)
static int inotify_handle_get_wd(struct inotify_handle *ih,
struct inotify_watch *watch)
{
int ret;
do {
if (unlikely(!idr_pre_get(&dev->idr, GFP_KERNEL)))
if (unlikely(!idr_pre_get(&ih->idr, GFP_KERNEL)))
return -ENOSPC;
ret = idr_get_new_above(&dev->idr, watch, dev->last_wd+1, &watch->wd);
ret = idr_get_new_above(&ih->idr, watch, ih->last_wd+1, &watch->wd);
} while (ret == -EAGAIN);
return ret;
}
if (likely(!ret))
ih->last_wd = watch->wd;
/*
* 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,
unsigned flags)
{
int error;
error = __user_walk(dirname, flags, nd);
if (error)
return error;
/* you can only watch an inode if you have read permissions on it */
error = vfs_permission(nd, MAY_READ);
if (error)
path_release(nd);
return error;
return ret;
}
/*
......@@ -422,67 +188,18 @@ static void set_dentry_child_flags(struct inode *inode, int watched)
}
/*
* create_watch - creates a watch on the given device.
*
* Callers must hold dev->mutex. 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
* inotify_find_handle - find the watch associated with the given inode and
* handle
*
* Callers must hold inode->inotify_mutex.
*/
static struct inotify_watch *inode_find_dev(struct inode *inode,
struct inotify_device *dev)
static struct inotify_watch *inode_find_handle(struct inode *inode,
struct inotify_handle *ih)
{
struct inotify_watch *watch;
list_for_each_entry(watch, &inode->inotify_watches, i_list) {
if (watch->dev == dev)
if (watch->ih == ih)
return watch;
}
......@@ -491,39 +208,34 @@ static struct inotify_watch *inode_find_dev(struct inode *inode,
/*
* remove_watch_no_event - remove_watch() without the IN_IGNORED event.
*
* Callers must hold both inode->inotify_mutex and ih->mutex.
*/
static void remove_watch_no_event(struct inotify_watch *watch,
struct inotify_device *dev)
struct inotify_handle *ih)
{
list_del(&watch->i_list);
list_del(&watch->d_list);
list_del(&watch->h_list);
if (!inotify_inode_watched(watch->inode))
set_dentry_child_flags(watch->inode, 0);
atomic_dec(&dev->user->inotify_watches);
idr_remove(&dev->idr, watch->wd);
put_inotify_watch(watch);
idr_remove(&ih->idr, watch->wd);
}
/*
* 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_mutex and dev->mutex. We drop a
* reference to the inode before returning.
* remove_watch - Remove a watch from both the handle and the inode. Sends
* the IN_IGNORED event signifying that the inode is no longer watched.
*
* 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.
* Callers must hold both inode->inotify_mutex and ih->mutex.
*/
static void remove_watch(struct inotify_watch *watch,struct inotify_device *dev)
static void remove_watch(struct inotify_watch *watch, struct inotify_handle *ih)
{
inotify_dev_queue_event(dev, watch, IN_IGNORED, 0, NULL);
remove_watch_no_event(watch, dev);
remove_watch_no_event(watch, ih);
ih->in_ops->handle_event(watch, watch->wd, IN_IGNORED, 0, NULL);
}
/* Kernel API */
/* Kernel API for producing events */
/*
* inotify_d_instantiate - instantiate dcache entry for inode
......@@ -576,14 +288,12 @@ void inotify_inode_queue_event(struct inode *inode, u32 mask, u32 cookie,
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);
mutex_lock(&dev->mutex);
inotify_dev_queue_event(dev, watch, mask, cookie, name);
struct inotify_handle *ih= watch->ih;
mutex_lock(&ih->mutex);
if (watch_mask & IN_ONESHOT)
remove_watch_no_event(watch, dev);
mutex_unlock(&dev->mutex);
put_inotify_watch(watch);
remove_watch_no_event(watch, ih);
ih->in_ops->handle_event(watch, watch->wd, mask, cookie, name);
mutex_unlock(&ih->mutex);
}
}
mutex_unlock(&inode->inotify_mutex);
......@@ -694,11 +404,12 @@ void inotify_unmount_inodes(struct list_head *list)
mutex_lock(&inode->inotify_mutex);
watches = &inode->inotify_watches;
list_for_each_entry_safe(watch, next_w, watches, i_list) {
struct inotify_device *dev = watch->dev;
mutex_lock(&dev->mutex);
inotify_dev_queue_event(dev, watch, IN_UNMOUNT,0,NULL);
remove_watch(watch, dev);
mutex_unlock(&dev->mutex);
struct inotify_handle *ih= watch->ih;
mutex_lock(&ih->mutex);
ih->in_ops->handle_event(watch, watch->wd, IN_UNMOUNT, 0,
NULL);
remove_watch(watch, ih);
mutex_unlock(&ih->mutex);
}
mutex_unlock(&inode->inotify_mutex);
iput(inode);
......@@ -718,432 +429,240 @@ void inotify_inode_is_dead(struct inode *inode)
mutex_lock(&inode->inotify_mutex);
list_for_each_entry_safe(watch, next, &inode->inotify_watches, i_list) {
struct inotify_device *dev = watch->dev;
mutex_lock(&dev->mutex);
remove_watch(watch, dev);
mutex_unlock(&dev->mutex);
struct inotify_handle *ih = watch->ih;
mutex_lock(&ih->mutex);
remove_watch(watch, ih);
mutex_unlock(&ih->mutex);
}
mutex_unlock(&inode->inotify_mutex);
}
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);
mutex_lock(&dev->mutex);
if (!list_empty(&dev->events))
ret = POLLIN | POLLRDNORM;
mutex_unlock(&dev->mutex);
return ret;
}
/* Kernel Consumer API */
static ssize_t inotify_read(struct file *file, char __user *buf,
size_t count, loff_t *pos)
/**
* inotify_init - allocate and initialize an inotify instance
* @ops: caller's inotify operations
*/
struct inotify_handle *inotify_init(const struct inotify_operations *ops)
{
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);
struct inotify_handle *ih;
mutex_lock(&dev->mutex);
events = !list_empty(&dev->events);
mutex_unlock(&dev->mutex);
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;
mutex_lock(&dev->mutex);
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;
}
ih = kmalloc(sizeof(struct inotify_handle), GFP_KERNEL);
if (unlikely(!ih))
return ERR_PTR(-ENOMEM);
remove_kevent(dev, kevent);
}
mutex_unlock(&dev->mutex);
idr_init(&ih->idr);
INIT_LIST_HEAD(&ih->watches);
mutex_init(&ih->mutex);
ih->last_wd = 0;
ih->in_ops = ops;
atomic_set(&ih->count, 0);
get_inotify_handle(ih);
return ret;
return ih;
}
EXPORT_SYMBOL_GPL(inotify_init);
static int inotify_release(struct inode *ignored, struct file *file)
/**
* inotify_destroy - clean up and destroy an inotify instance
* @ih: inotify handle
*/
void inotify_destroy(struct inotify_handle *ih)
{
struct inotify_device *dev = file->private_data;
/*
* Destroy all of the watches on this device. Unfortunately, not very
* Destroy all of the watches for this handle. 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_mutex before dev->mutex. The following works.
* hold inode->inotify_mutex before ih->mutex. The following works.
*/
while (1) {
struct inotify_watch *watch;
struct list_head *watches;
struct inode *inode;
mutex_lock(&dev->mutex);
watches = &dev->watches;
mutex_lock(&ih->mutex);
watches = &ih->watches;
if (list_empty(watches)) {
mutex_unlock(&dev->mutex);
mutex_unlock(&ih->mutex);
break;
}
watch = list_entry(watches->next, struct inotify_watch, d_list);
watch = list_entry(watches->next, struct inotify_watch, h_list);
get_inotify_watch(watch);
mutex_unlock(&dev->mutex);
mutex_unlock(&ih->mutex);
inode = watch->inode;
mutex_lock(&inode->inotify_mutex);
mutex_lock(&dev->mutex);
mutex_lock(&ih->mutex);
/* make sure we didn't race with another list removal */
if (likely(idr_find(&dev->idr, watch->wd)))
remove_watch_no_event(watch, dev);
if (likely(idr_find(&ih->idr, watch->wd))) {
remove_watch_no_event(watch, ih);
put_inotify_watch(watch);
}
mutex_unlock(&dev->mutex);
mutex_unlock(&ih->mutex);
mutex_unlock(&inode->inotify_mutex);
put_inotify_watch(watch);
}
/* destroy all of the events on this device */
mutex_lock(&dev->mutex);
while (!list_empty(&dev->events))
inotify_dev_event_dequeue(dev);
mutex_unlock(&dev->mutex);
/* free this device: the put matching the get in inotify_init() */
put_inotify_dev(dev);
return 0;
/* free this handle: the put matching the get in inotify_init() */
put_inotify_handle(ih);
}
EXPORT_SYMBOL_GPL(inotify_destroy);
/*
* inotify_ignore - remove a given wd from this inotify instance.
/**
* inotify_find_update_watch - find and update the mask of an existing watch
* @ih: inotify handle
* @inode: inode's watch to update
* @mask: mask of events to watch
*
* Can sleep.
* Caller must pin given inode (via nameidata).
*/
static int inotify_ignore(struct inotify_device *dev, s32 wd)
s32 inotify_find_update_watch(struct inotify_handle *ih, struct inode *inode,
u32 mask)
{
struct inotify_watch *watch;
struct inode *inode;
struct inotify_watch *old;
int mask_add = 0;
int ret;
mutex_lock(&dev->mutex);
watch = idr_find(&dev->idr, wd);
if (unlikely(!watch)) {
mutex_unlock(&dev->mutex);
if (mask & IN_MASK_ADD)
mask_add = 1;
/* don't allow invalid bits: we don't want flags set */
mask &= IN_ALL_EVENTS | IN_ONESHOT;
if (unlikely(!mask))
return -EINVAL;
}
get_inotify_watch(watch);
inode = watch->inode;
mutex_unlock(&dev->mutex);
mutex_lock(&inode->inotify_mutex);
mutex_lock(&dev->mutex);
/* make sure that we did not race */
if (likely(idr_find(&dev->idr, wd) == watch))
remove_watch(watch, dev);
mutex_unlock(&dev->mutex);
mutex_unlock(&inode->inotify_mutex);
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;
mutex_lock(&ih->mutex);
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 const 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;
/*
* Handle the case of re-adding a watch on an (inode,ih) pair that we
* are already watching. We just update the mask and return its wd.
*/
old = inode_find_handle(inode, ih);
if (unlikely(!old)) {
ret = -ENOENT;
goto out;
}
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);
mutex_init(&dev->mutex);
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);
if (mask_add)
old->mask |= mask;
else
old->mask = mask;
ret = old->wd;
out:
mutex_unlock(&ih->mutex);
mutex_unlock(&inode->inotify_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(inotify_find_update_watch);
asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask)
/**
* inotify_add_watch - add a watch to an inotify instance
* @ih: inotify handle
* @watch: caller allocated watch structure
* @inode: inode to watch
* @mask: mask of events to watch
*
* Caller must pin given inode (via nameidata).
* Caller must ensure it only calls inotify_add_watch() once per watch.
* Calls inotify_handle_get_wd() so may sleep.
*/
s32 inotify_add_watch(struct inotify_handle *ih, struct inotify_watch *watch,
struct inode *inode, u32 mask)
{
struct inotify_watch *watch, *old;
struct inode *inode;
struct inotify_device *dev;
struct nameidata nd;
struct file *filp;
int ret, fput_needed;
int mask_add = 0;
unsigned flags = 0;
filp = fget_light(fd, &fput_needed);
if (unlikely(!filp))
return -EBADF;
int ret = 0;
/* verify that this is indeed an inotify instance */
if (unlikely(filp->f_op != &inotify_fops)) {
ret = -EINVAL;
goto fput_and_out;
}
/* don't allow invalid bits: we don't want flags set */
mask &= IN_ALL_EVENTS | IN_ONESHOT;
if (unlikely(!mask))
return -EINVAL;
watch->mask = mask;
if (!(mask & IN_DONT_FOLLOW))
flags |= LOOKUP_FOLLOW;
if (mask & IN_ONLYDIR)
flags |= LOOKUP_DIRECTORY;
mutex_lock(&inode->inotify_mutex);
mutex_lock(&ih->mutex);
ret = find_inode(path, &nd, flags);
/* Initialize a new watch */
ret = inotify_handle_get_wd(ih, watch);
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;
mutex_lock(&inode->inotify_mutex);
mutex_lock(&dev->mutex);
goto out;
ret = watch->wd;
if (mask & IN_MASK_ADD)
mask_add = 1;
atomic_set(&watch->count, 0);
INIT_LIST_HEAD(&watch->h_list);
INIT_LIST_HEAD(&watch->i_list);
/* don't let user-space set invalid bits: we don't want flags set */
mask &= IN_ALL_EVENTS | IN_ONESHOT;
if (unlikely(!mask)) {
ret = -EINVAL;
goto out;
}
/* save a reference to handle and bump the count to make it official */
get_inotify_handle(ih);
watch->ih = ih;
/*
* 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.
* 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.
*/
old = inode_find_dev(inode, dev);
if (unlikely(old)) {
if (mask_add)
old->mask |= mask;
else
old->mask = mask;
ret = old->wd;
goto out;
}
watch->inode = igrab(inode);
watch = create_watch(dev, mask, inode);
if (unlikely(IS_ERR(watch))) {
ret = PTR_ERR(watch);
goto out;
}
get_inotify_watch(watch); /* initial get */
if (!inotify_inode_watched(inode))
set_dentry_child_flags(inode, 1);
/* Add the watch to the device's and the inode's list */
list_add(&watch->d_list, &dev->watches);
/* Add the watch to the handle's and the inode's list */
list_add(&watch->h_list, &ih->watches);
list_add(&watch->i_list, &inode->inotify_watches);
ret = watch->wd;
out:
mutex_unlock(&dev->mutex);
mutex_unlock(&ih->mutex);
mutex_unlock(&inode->inotify_mutex);
path_release(&nd);
fput_and_out:
fput_light(filp, fput_needed);
return ret;
}
EXPORT_SYMBOL_GPL(inotify_add_watch);
asmlinkage long sys_inotify_rm_watch(int fd, u32 wd)
/**
* inotify_rm_wd - remove a watch from an inotify instance
* @ih: inotify handle
* @wd: watch descriptor to remove
*
* Can sleep.
*/
int inotify_rm_wd(struct inotify_handle *ih, u32 wd)
{
struct file *filp;
struct inotify_device *dev;
int ret, fput_needed;
filp = fget_light(fd, &fput_needed);
if (unlikely(!filp))
return -EBADF;
struct inotify_watch *watch;
struct inode *inode;
/* verify that this is indeed an inotify instance */
if (unlikely(filp->f_op != &inotify_fops)) {
ret = -EINVAL;
goto out;
mutex_lock(&ih->mutex);
watch = idr_find(&ih->idr, wd);
if (unlikely(!watch)) {
mutex_unlock(&ih->mutex);
return -EINVAL;
}
get_inotify_watch(watch);
inode = watch->inode;
mutex_unlock(&ih->mutex);
dev = filp->private_data;
ret = inotify_ignore(dev, wd);
mutex_lock(&inode->inotify_mutex);
mutex_lock(&ih->mutex);
out:
fput_light(filp, fput_needed);
return ret;
}
/* make sure that we did not race */
if (likely(idr_find(&ih->idr, wd) == watch))
remove_watch(watch, ih);
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);
}
mutex_unlock(&ih->mutex);
mutex_unlock(&inode->inotify_mutex);
put_inotify_watch(watch);
static struct file_system_type inotify_fs_type = {
.name = "inotifyfs",
.get_sb = inotify_get_sb,
.kill_sb = kill_anon_super,
};
return 0;
}
EXPORT_SYMBOL_GPL(inotify_rm_wd);
/*
* 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().
* inotify_setup - core initialization function
*/
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;
}
......
fs/inotify_user.c 0 → 100644
浏览文件 @ 2d9048e2
/*
* fs/inotify_user.c - inotify support for userspace
*
* Authors:
* John McCutchan <ttb@tentacle.dhs.org>
* Robert Love <rml@novell.com>
*
* Copyright (C) 2005 John McCutchan
* Copyright 2006 Hewlett-Packard Development Company, L.P.
*
* 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/kernel.h>
#include <linux/sched.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/inotify.h>
#include <linux/syscalls.h>
#include <asm/ioctls.h>
static kmem_cache_t *watch_cachep __read_mostly;
static kmem_cache_t *event_cachep __read_mostly;
static struct vfsmount *inotify_mnt __read_mostly;
/* these are configurable via /proc/sys/fs/inotify/ */
int inotify_max_user_instances __read_mostly;
int inotify_max_user_watches __read_mostly;
int inotify_max_queued_events __read_mostly;
/*
* Lock ordering:
*
* inotify_dev->up_mutex (ensures we don't re-add the same watch)
* inode->inotify_mutex (protects inode's watch list)
* inotify_handle->mutex (protects inotify_handle's watch list)
* inotify_dev->ev_mutex (protects device's event queue)
*/
/*
* Lifetimes of the main data structures:
*
* inotify_device: Lifetime is managed by reference count, from
* sys_inotify_init() until release. Additional references can bump the count
* via get_inotify_dev() and drop the count via put_inotify_dev().
*
* inotify_user_watch: Lifetime is from create_watch() to the receipt of an
* IN_IGNORED event from inotify, or when using IN_ONESHOT, to receipt of the
* first event, or to inotify_destroy().
*/
/*
* struct inotify_device - represents an inotify instance
*
* This structure is protected by the mutex 'mutex'.
*/
struct inotify_device {
wait_queue_head_t wq; /* wait queue for i/o */
struct mutex ev_mutex; /* protects event queue */
struct mutex up_mutex; /* synchronizes watch updates */
struct list_head events; /* list of queued events */
atomic_t count; /* reference count */
struct user_struct *user; /* user who opened this dev */
struct inotify_handle *ih; /* inotify handle */
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 */
};
/*
* 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->ev_mutex 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_user_watch - our version of an inotify_watch, we add
* a reference to the associated inotify_device.
*/
struct inotify_user_watch {
struct inotify_device *dev; /* associated device */
struct inotify_watch wdata; /* inotify watch data */
};
#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);
}
}
/*
* free_inotify_user_watch - cleans up the watch and its references
*/
static void free_inotify_user_watch(struct inotify_watch *w)
{
struct inotify_user_watch *watch;
struct inotify_device *dev;
watch = container_of(w, struct inotify_user_watch, wdata);
dev = watch->dev;
atomic_dec(&dev->user->inotify_watches);
put_inotify_dev(dev);
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->ev_mutex.
*/
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 - event handler registered with core inotify, adds
* a new event to the given device
*
* Can sleep (calls kernel_event()).
*/
static void inotify_dev_queue_event(struct inotify_watch *w, u32 wd, u32 mask,
u32 cookie, const char *name)
{
struct inotify_user_watch *watch;
struct inotify_device *dev;
struct inotify_kernel_event *kevent, *last;
watch = container_of(w, struct inotify_user_watch, wdata);
dev = watch->dev;
mutex_lock(&dev->ev_mutex);
/* we can safely put the watch as we don't reference it while
* generating the event
*/
if (mask & IN_IGNORED || mask & IN_ONESHOT)
put_inotify_watch(w); /* final put */
/* 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 == wd &&
last->event.cookie == cookie) {
const char *lastname = last->name;
if (!name && !lastname)
goto out;
if (name && lastname && !strcmp(lastname, name))
goto out;
}
/* the queue overflowed and we already sent the Q_OVERFLOW event */
if (unlikely(dev->event_count > dev->max_events))
goto out;
/* 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(wd, mask, cookie, name);
if (unlikely(!kevent))
goto out;
/* 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);
out:
mutex_unlock(&dev->ev_mutex);
}
/*
* remove_kevent - cleans up and ultimately frees the given kevent
*
* Caller must hold dev->ev_mutex.
*/
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->ev_mutex.
*/
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);
}
}
/*
* 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,
unsigned flags)
{
int error;
error = __user_walk(dirname, flags, nd);
if (error)
return error;
/* you can only watch an inode if you have read permissions on it */
error = vfs_permission(nd, MAY_READ);
if (error)
path_release(nd);
return error;
}
/*
* create_watch - creates a watch on the given device.
*
* Callers must hold dev->up_mutex.
*/
static int create_watch(struct inotify_device *dev, struct inode *inode,
u32 mask)
{
struct inotify_user_watch *watch;
int ret;
if (atomic_read(&dev->user->inotify_watches) >=
inotify_max_user_watches)
return -ENOSPC;
watch = kmem_cache_alloc(watch_cachep, GFP_KERNEL);
if (unlikely(!watch))
return -ENOMEM;
/* save a reference to device and bump the count to make it official */
get_inotify_dev(dev);
watch->dev = dev;
atomic_inc(&dev->user->inotify_watches);
ret = inotify_add_watch(dev->ih, &watch->wdata, inode, mask);
if (ret < 0)
free_inotify_user_watch(&watch->wdata);
return ret;
}
/* 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);
mutex_lock(&dev->ev_mutex);
if (!list_empty(&dev->events))
ret = POLLIN | POLLRDNORM;
mutex_unlock(&dev->ev_mutex);
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);
mutex_lock(&dev->ev_mutex);
events = !list_empty(&dev->events);
mutex_unlock(&dev->ev_mutex);
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;
mutex_lock(&dev->ev_mutex);
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);
}
mutex_unlock(&dev->ev_mutex);
return ret;
}
static int inotify_release(struct inode *ignored, struct file *file)
{
struct inotify_device *dev = file->private_data;
inotify_destroy(dev->ih);
/* destroy all of the events on this device */
mutex_lock(&dev->ev_mutex);
while (!list_empty(&dev->events))
inotify_dev_event_dequeue(dev);
mutex_unlock(&dev->ev_mutex);
/* free this device: the put matching the get in inotify_init() */
put_inotify_dev(dev);
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 const struct file_operations inotify_fops = {
.poll = inotify_poll,
.read = inotify_read,
.release = inotify_release,
.unlocked_ioctl = inotify_ioctl,
.compat_ioctl = inotify_ioctl,
};
static const struct inotify_operations inotify_user_ops = {
.handle_event = inotify_dev_queue_event,
.destroy_watch = free_inotify_user_watch,
};
asmlinkage long sys_inotify_init(void)
{
struct inotify_device *dev;
struct inotify_handle *ih;
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;
}
ih = inotify_init(&inotify_user_ops);
if (unlikely(IS_ERR(ih))) {
ret = PTR_ERR(ih);
goto out_free_dev;
}
dev->ih = ih;
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;
INIT_LIST_HEAD(&dev->events);
init_waitqueue_head(&dev->wq);
mutex_init(&dev->ev_mutex);
mutex_init(&dev->up_mutex);
dev->event_count = 0;
dev->queue_size = 0;
dev->max_events = inotify_max_queued_events;
dev->user = user;
atomic_set(&dev->count, 0);
get_inotify_dev(dev);
atomic_inc(&user->inotify_devs);
fd_install(fd, filp);
return fd;
out_free_dev:
kfree(dev);
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 inode *inode;
struct inotify_device *dev;
struct nameidata nd;
struct file *filp;
int ret, fput_needed;
unsigned flags = 0;
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;
}
if (!(mask & IN_DONT_FOLLOW))
flags |= LOOKUP_FOLLOW;
if (mask & IN_ONLYDIR)
flags |= LOOKUP_DIRECTORY;
ret = find_inode(path, &nd, flags);
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;
mutex_lock(&dev->up_mutex);
ret = inotify_find_update_watch(dev->ih, inode, mask);
if (ret == -ENOENT)
ret = create_watch(dev, inode, mask);
mutex_unlock(&dev->up_mutex);
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;
/* we free our watch data when we get IN_IGNORED */
ret = inotify_rm_wd(dev->ih, 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_user_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_user_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;
watch_cachep = kmem_cache_create("inotify_watch_cache",
sizeof(struct inotify_user_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_user_setup);
include/linux/inotify.h
浏览文件 @ 2d9048e2
......@@ -68,8 +68,37 @@ struct inotify_event {
#include <linux/dcache.h>
#include <linux/fs.h>
/*
* struct inotify_watch - represents a watch request on a specific inode
*
* h_list is protected by ih->mutex of the associated inotify_handle.
* i_list, mask are protected by inode->inotify_mutex of the associated inode.
* ih, inode, and wd are never written to once the watch is created.
*
* Callers must use the established inotify interfaces to access inotify_watch
* contents. The content of this structure is private to the inotify
* implementation.
*/
struct inotify_watch {
struct list_head h_list; /* entry in inotify_handle's list */
struct list_head i_list; /* entry in inode's list */
atomic_t count; /* reference count */
struct inotify_handle *ih; /* associated inotify handle */
struct inode *inode; /* associated inode */
__s32 wd; /* watch descriptor */
__u32 mask; /* event mask for this watch */
};
struct inotify_operations {
void (*handle_event)(struct inotify_watch *, u32, u32, u32,
const char *);
void (*destroy_watch)(struct inotify_watch *);
};
#ifdef CONFIG_INOTIFY
/* Kernel API for producing events */
extern void inotify_d_instantiate(struct dentry *, struct inode *);
extern void inotify_d_move(struct dentry *);
extern void inotify_inode_queue_event(struct inode *, __u32, __u32,
......@@ -80,6 +109,18 @@ extern void inotify_unmount_inodes(struct list_head *);
extern void inotify_inode_is_dead(struct inode *);
extern u32 inotify_get_cookie(void);
/* Kernel Consumer API */
extern struct inotify_handle *inotify_init(const struct inotify_operations *);
extern void inotify_destroy(struct inotify_handle *);
extern __s32 inotify_find_update_watch(struct inotify_handle *, struct inode *,
u32);
extern __s32 inotify_add_watch(struct inotify_handle *, struct inotify_watch *,
struct inode *, __u32);
extern int inotify_rm_wd(struct inotify_handle *, __u32);
extern void get_inotify_watch(struct inotify_watch *);
extern void put_inotify_watch(struct inotify_watch *);
#else
static inline void inotify_d_instantiate(struct dentry *dentry,
......@@ -116,6 +157,41 @@ static inline u32 inotify_get_cookie(void)
return 0;
}
static inline struct inotify_handle *inotify_init(const struct inotify_operations *ops)
{
return ERR_PTR(-EOPNOTSUPP);
}
static inline void inotify_destroy(struct inotify_handle *ih)
{
}
static inline __s32 inotify_find_update_watch(struct inotify_handle *ih,
struct inode *inode, u32 mask)
{
return -EOPNOTSUPP;
}
static inline __s32 inotify_add_watch(struct inotify_handle *ih,
struct inotify_watch *watch,
struct inode *inode, __u32 mask)
{
return -EOPNOTSUPP;
}
static inline int inotify_rm_wd(struct inotify_handle *ih, __u32 wd)
{
return -EOPNOTSUPP;
}
static inline void get_inotify_watch(struct inotify_watch *watch)
{
}
static inline void put_inotify_watch(struct inotify_watch *watch)
{
}
#endif /* CONFIG_INOTIFY */
#endif /* __KERNEL __ */
......
include/linux/sched.h
浏览文件 @ 2d9048e2
......@@ -494,7 +494,7 @@ struct user_struct {
atomic_t processes; /* How many processes does this user have? */
atomic_t files; /* How many open files does this user have? */
atomic_t sigpending; /* How many pending signals does this user have? */
#ifdef CONFIG_INOTIFY
#ifdef CONFIG_INOTIFY_USER
atomic_t inotify_watches; /* How many inotify watches does this user have? */
atomic_t inotify_devs; /* How many inotify devs does this user have opened? */
#endif
......
kernel/sysctl.c
浏览文件 @ 2d9048e2
......@@ -150,7 +150,7 @@ extern ctl_table random_table[];
#ifdef CONFIG_UNIX98_PTYS
extern ctl_table pty_table[];
#endif
#ifdef CONFIG_INOTIFY
#ifdef CONFIG_INOTIFY_USER
extern ctl_table inotify_table[];
#endif
......@@ -1028,7 +1028,7 @@ static ctl_table fs_table[] = {
.mode = 0644,
.proc_handler = &proc_doulongvec_minmax,
},
#ifdef CONFIG_INOTIFY
#ifdef CONFIG_INOTIFY_USER
{
.ctl_name = FS_INOTIFY,
.procname = "inotify",
......
kernel/user.c
浏览文件 @ 2d9048e2
......@@ -140,7 +140,7 @@ struct user_struct * alloc_uid(uid_t uid)
atomic_set(&new->processes, 0);
atomic_set(&new->files, 0);
atomic_set(&new->sigpending, 0);
#ifdef CONFIG_INOTIFY
#ifdef CONFIG_INOTIFY_USER
atomic_set(&new->inotify_watches, 0);
atomic_set(&new->inotify_devs, 0);
#endif
......
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