diff options
| -rw-r--r-- | fs/Kconfig | 24 | ||||
| -rw-r--r-- | fs/Makefile | 1 | ||||
| -rw-r--r-- | fs/inotify.c | 941 | ||||
| -rw-r--r-- | fs/inotify_user.c | 717 | ||||
| -rw-r--r-- | include/linux/inotify.h | 76 | ||||
| -rw-r--r-- | include/linux/sched.h | 2 | ||||
| -rw-r--r-- | kernel/sysctl.c | 4 | ||||
| -rw-r--r-- | kernel/user.c | 2 |
8 files changed, 1046 insertions, 721 deletions
@@ -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 diff --git a/fs/Makefile b/fs/Makefile index 078d3d1..d0ea6bf 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -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 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_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; } 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 @@ 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 __ */ diff --git a/include/linux/sched.h b/include/linux/sched.h index 29b7d4f..864e5a7 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -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 diff --git a/kernel/sysctl.c b/kernel/sysctl.c index e82726f..0d656e6 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -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", 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 |
