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Subject[PATCH] inotify: 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.

These patches are basically identical to my previous post:

http://lkml.org/lkml/2006/5/25/314

except that I've split the original patch between movement of existing
inotify code and introduction of new functionality, as Andrew requested.

I based the patches off of 2.6.17-rc5.

Thanks for reviewing.

Signed-off-by: Amy Griffis <amy.griffis@hp.com>

---
fs/Kconfig | 24 +
fs/Makefile | 1
fs/inotify.c | 941 +++++++++++------------------------------------
fs/inotify_user.c | 717 ++++++++++++++++++++++++++++++++++++
include/linux/inotify.h | 76 ++++
include/linux/sched.h | 2
kernel/sysctl.c | 4
kernel/user.c | 2
8 files changed, 1046 insertions(+), 721 deletions(-)
create mode 100644 fs/inotify_user.c
a23ad01a5cc42d02b1c251be310f6e89cdc8de10
diff --git a/fs/Kconfig b/fs/Kconfig
index 86e5c3f..2328cb3 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -396,18 +396,30 @@ 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
diff --git a/fs/Makefile b/fs/Makefile
index 7652ccb..69d4658 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -13,6 +13,7 @@ obj-y := open.o read_write.o file_table.
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

diff --git a/fs/inotify.c b/fs/inotify.c
index 732ec4b..a1bedf3 100644
--- a/fs/inotify.c
+++ b/fs/inotify.c
@@ -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_mos
* 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(struc
}

/*
- * 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_

/*
* 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 in
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_
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

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;
}

diff --git a/fs/inotify_user.c b/fs/inotify_user.c
new file mode 100644
index 0000000..845dc79
--- /dev/null
+++ b/fs/inotify_user.c
@@ -0,0 +1,717 @@
+/*
+ * 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);
diff --git a/include/linux/inotify.h b/include/linux/inotify.h
index 71aa155..68b6e01 100644
--- a/include/linux/inotify.h
+++ b/include/linux/inotify.h
@@ -68,8 +68,37 @@ #ifdef __KERNEL__
#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(struc
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(voi
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 __ */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index d700cee..ab5f3e2 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -502,7 +502,7 @@ 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
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 5929337..5edbeae 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -170,7 +170,7 @@ 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

@@ -1194,7 +1194,7 @@ #ifdef CONFIG_MMU
.mode = 0644,
.proc_handler = &proc_doulongvec_minmax,
},
-#ifdef CONFIG_INOTIFY
+#ifdef CONFIG_INOTIFY_USER
{
.ctl_name = FS_INOTIFY,
.procname = "inotify",
diff --git a/kernel/user.c b/kernel/user.c
index 2116642..4b1eb74 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -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
--
1.3.0
-
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