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![Arnd Bergmann](/assets/img/avatar_default.png)
The spufs file system creates files in a directory before instantiating the
directory itself, which causes a NULL pointer access in
inotify_d_instantiate since c32ccd87bf
.
I'd like to keep this behavior since it means that the user will not have
access to files in the directory before I know that I succeed in creating
everything in it. This patch adds a simple check for the inode to keep
that working.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1147 lines
29 KiB
C
1147 lines
29 KiB
C
/*
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* fs/inotify.c - inode-based file event notifications
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*
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* Authors:
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* John McCutchan <ttb@tentacle.dhs.org>
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* Robert Love <rml@novell.com>
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*
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* Copyright (C) 2005 John McCutchan
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2, or (at your option) any
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* later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <linux/idr.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/poll.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <linux/writeback.h>
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#include <linux/inotify.h>
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#include <linux/syscalls.h>
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#include <asm/ioctls.h>
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static atomic_t inotify_cookie;
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static kmem_cache_t *watch_cachep __read_mostly;
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static kmem_cache_t *event_cachep __read_mostly;
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static struct vfsmount *inotify_mnt __read_mostly;
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/* these are configurable via /proc/sys/fs/inotify/ */
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int inotify_max_user_instances __read_mostly;
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int inotify_max_user_watches __read_mostly;
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int inotify_max_queued_events __read_mostly;
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/*
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* Lock ordering:
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*
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* dentry->d_lock (used to keep d_move() away from dentry->d_parent)
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* iprune_mutex (synchronize shrink_icache_memory())
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* inode_lock (protects the super_block->s_inodes list)
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* inode->inotify_mutex (protects inode->inotify_watches and watches->i_list)
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* inotify_dev->mutex (protects inotify_device and watches->d_list)
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*/
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/*
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* Lifetimes of the three main data structures--inotify_device, inode, and
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* inotify_watch--are managed by reference count.
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*
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* inotify_device: Lifetime is from inotify_init() until release. Additional
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* references can bump the count via get_inotify_dev() and drop the count via
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* put_inotify_dev().
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*
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* inotify_watch: Lifetime is from create_watch() to destory_watch().
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* Additional references can bump the count via get_inotify_watch() and drop
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* the count via put_inotify_watch().
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*
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* inode: Pinned so long as the inode is associated with a watch, from
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* create_watch() to put_inotify_watch().
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*/
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/*
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* struct inotify_device - represents an inotify instance
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*
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* This structure is protected by the mutex 'mutex'.
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*/
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struct inotify_device {
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wait_queue_head_t wq; /* wait queue for i/o */
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struct idr idr; /* idr mapping wd -> watch */
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struct mutex mutex; /* protects this bad boy */
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struct list_head events; /* list of queued events */
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struct list_head watches; /* list of watches */
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atomic_t count; /* reference count */
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struct user_struct *user; /* user who opened this dev */
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unsigned int queue_size; /* size of the queue (bytes) */
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unsigned int event_count; /* number of pending events */
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unsigned int max_events; /* maximum number of events */
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u32 last_wd; /* the last wd allocated */
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};
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/*
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* struct inotify_kernel_event - An inotify event, originating from a watch and
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* queued for user-space. A list of these is attached to each instance of the
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* device. In read(), this list is walked and all events that can fit in the
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* buffer are returned.
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*
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* Protected by dev->mutex of the device in which we are queued.
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*/
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struct inotify_kernel_event {
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struct inotify_event event; /* the user-space event */
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struct list_head list; /* entry in inotify_device's list */
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char *name; /* filename, if any */
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};
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/*
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* struct inotify_watch - represents a watch request on a specific inode
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*
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* d_list is protected by dev->mutex of the associated watch->dev.
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* i_list and mask are protected by inode->inotify_mutex of the associated inode.
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* dev, inode, and wd are never written to once the watch is created.
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*/
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struct inotify_watch {
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struct list_head d_list; /* entry in inotify_device's list */
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struct list_head i_list; /* entry in inode's list */
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atomic_t count; /* reference count */
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struct inotify_device *dev; /* associated device */
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struct inode *inode; /* associated inode */
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s32 wd; /* watch descriptor */
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u32 mask; /* event mask for this watch */
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};
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#ifdef CONFIG_SYSCTL
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#include <linux/sysctl.h>
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static int zero;
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ctl_table inotify_table[] = {
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{
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.ctl_name = INOTIFY_MAX_USER_INSTANCES,
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.procname = "max_user_instances",
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.data = &inotify_max_user_instances,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = &proc_dointvec_minmax,
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.strategy = &sysctl_intvec,
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.extra1 = &zero,
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},
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{
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.ctl_name = INOTIFY_MAX_USER_WATCHES,
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.procname = "max_user_watches",
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.data = &inotify_max_user_watches,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = &proc_dointvec_minmax,
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.strategy = &sysctl_intvec,
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.extra1 = &zero,
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},
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{
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.ctl_name = INOTIFY_MAX_QUEUED_EVENTS,
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.procname = "max_queued_events",
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.data = &inotify_max_queued_events,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = &proc_dointvec_minmax,
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.strategy = &sysctl_intvec,
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.extra1 = &zero
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},
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{ .ctl_name = 0 }
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};
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#endif /* CONFIG_SYSCTL */
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static inline void get_inotify_dev(struct inotify_device *dev)
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{
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atomic_inc(&dev->count);
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}
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static inline void put_inotify_dev(struct inotify_device *dev)
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{
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if (atomic_dec_and_test(&dev->count)) {
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atomic_dec(&dev->user->inotify_devs);
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free_uid(dev->user);
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idr_destroy(&dev->idr);
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kfree(dev);
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}
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}
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static inline void get_inotify_watch(struct inotify_watch *watch)
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{
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atomic_inc(&watch->count);
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}
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/*
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* put_inotify_watch - decrements the ref count on a given watch. cleans up
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* the watch and its references if the count reaches zero.
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*/
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static inline void put_inotify_watch(struct inotify_watch *watch)
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{
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if (atomic_dec_and_test(&watch->count)) {
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put_inotify_dev(watch->dev);
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iput(watch->inode);
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kmem_cache_free(watch_cachep, watch);
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}
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}
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/*
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* kernel_event - create a new kernel event with the given parameters
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*
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* This function can sleep.
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*/
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static struct inotify_kernel_event * kernel_event(s32 wd, u32 mask, u32 cookie,
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const char *name)
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{
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struct inotify_kernel_event *kevent;
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kevent = kmem_cache_alloc(event_cachep, GFP_KERNEL);
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if (unlikely(!kevent))
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return NULL;
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/* we hand this out to user-space, so zero it just in case */
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memset(&kevent->event, 0, sizeof(struct inotify_event));
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kevent->event.wd = wd;
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kevent->event.mask = mask;
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kevent->event.cookie = cookie;
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INIT_LIST_HEAD(&kevent->list);
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if (name) {
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size_t len, rem, event_size = sizeof(struct inotify_event);
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/*
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* We need to pad the filename so as to properly align an
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* array of inotify_event structures. Because the structure is
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* small and the common case is a small filename, we just round
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* up to the next multiple of the structure's sizeof. This is
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* simple and safe for all architectures.
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*/
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len = strlen(name) + 1;
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rem = event_size - len;
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if (len > event_size) {
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rem = event_size - (len % event_size);
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if (len % event_size == 0)
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rem = 0;
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}
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kevent->name = kmalloc(len + rem, GFP_KERNEL);
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if (unlikely(!kevent->name)) {
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kmem_cache_free(event_cachep, kevent);
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return NULL;
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}
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memcpy(kevent->name, name, len);
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if (rem)
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memset(kevent->name + len, 0, rem);
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kevent->event.len = len + rem;
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} else {
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kevent->event.len = 0;
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kevent->name = NULL;
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}
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return kevent;
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}
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/*
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* inotify_dev_get_event - return the next event in the given dev's queue
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*
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* Caller must hold dev->mutex.
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*/
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static inline struct inotify_kernel_event *
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inotify_dev_get_event(struct inotify_device *dev)
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{
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return list_entry(dev->events.next, struct inotify_kernel_event, list);
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}
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/*
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* inotify_dev_queue_event - add a new event to the given device
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*
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* Caller must hold dev->mutex. Can sleep (calls kernel_event()).
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*/
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static void inotify_dev_queue_event(struct inotify_device *dev,
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struct inotify_watch *watch, u32 mask,
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u32 cookie, const char *name)
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{
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struct inotify_kernel_event *kevent, *last;
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/* coalescing: drop this event if it is a dupe of the previous */
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last = inotify_dev_get_event(dev);
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if (last && last->event.mask == mask && last->event.wd == watch->wd &&
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last->event.cookie == cookie) {
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const char *lastname = last->name;
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if (!name && !lastname)
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return;
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if (name && lastname && !strcmp(lastname, name))
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return;
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}
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/* the queue overflowed and we already sent the Q_OVERFLOW event */
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if (unlikely(dev->event_count > dev->max_events))
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return;
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/* if the queue overflows, we need to notify user space */
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if (unlikely(dev->event_count == dev->max_events))
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kevent = kernel_event(-1, IN_Q_OVERFLOW, cookie, NULL);
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else
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kevent = kernel_event(watch->wd, mask, cookie, name);
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if (unlikely(!kevent))
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return;
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/* queue the event and wake up anyone waiting */
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dev->event_count++;
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dev->queue_size += sizeof(struct inotify_event) + kevent->event.len;
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list_add_tail(&kevent->list, &dev->events);
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wake_up_interruptible(&dev->wq);
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}
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/*
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* remove_kevent - cleans up and ultimately frees the given kevent
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*
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* Caller must hold dev->mutex.
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*/
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static void remove_kevent(struct inotify_device *dev,
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struct inotify_kernel_event *kevent)
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{
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list_del(&kevent->list);
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dev->event_count--;
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dev->queue_size -= sizeof(struct inotify_event) + kevent->event.len;
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kfree(kevent->name);
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kmem_cache_free(event_cachep, kevent);
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}
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/*
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* inotify_dev_event_dequeue - destroy an event on the given device
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*
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* Caller must hold dev->mutex.
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*/
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static void inotify_dev_event_dequeue(struct inotify_device *dev)
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{
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if (!list_empty(&dev->events)) {
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struct inotify_kernel_event *kevent;
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kevent = inotify_dev_get_event(dev);
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remove_kevent(dev, kevent);
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}
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}
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/*
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* inotify_dev_get_wd - returns the next WD for use by the given dev
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*
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* Callers must hold dev->mutex. This function can sleep.
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*/
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static int inotify_dev_get_wd(struct inotify_device *dev,
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struct inotify_watch *watch)
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{
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int ret;
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do {
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if (unlikely(!idr_pre_get(&dev->idr, GFP_KERNEL)))
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return -ENOSPC;
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ret = idr_get_new_above(&dev->idr, watch, dev->last_wd+1, &watch->wd);
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} while (ret == -EAGAIN);
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return ret;
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}
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/*
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* find_inode - resolve a user-given path to a specific inode and return a nd
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*/
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static int find_inode(const char __user *dirname, struct nameidata *nd,
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unsigned flags)
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{
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int error;
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error = __user_walk(dirname, flags, nd);
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if (error)
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return error;
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/* you can only watch an inode if you have read permissions on it */
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error = vfs_permission(nd, MAY_READ);
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if (error)
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path_release(nd);
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return error;
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}
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/*
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* inotify_inode_watched - returns nonzero if there are watches on this inode
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* and zero otherwise. We call this lockless, we do not care if we race.
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*/
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static inline int inotify_inode_watched(struct inode *inode)
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{
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return !list_empty(&inode->inotify_watches);
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}
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/*
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* Get child dentry flag into synch with parent inode.
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* Flag should always be clear for negative dentrys.
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*/
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static void set_dentry_child_flags(struct inode *inode, int watched)
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{
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struct dentry *alias;
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spin_lock(&dcache_lock);
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list_for_each_entry(alias, &inode->i_dentry, d_alias) {
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struct dentry *child;
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list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
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if (!child->d_inode) {
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WARN_ON(child->d_flags & DCACHE_INOTIFY_PARENT_WATCHED);
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continue;
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}
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spin_lock(&child->d_lock);
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if (watched) {
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WARN_ON(child->d_flags &
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DCACHE_INOTIFY_PARENT_WATCHED);
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child->d_flags |= DCACHE_INOTIFY_PARENT_WATCHED;
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} else {
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WARN_ON(!(child->d_flags &
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DCACHE_INOTIFY_PARENT_WATCHED));
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child->d_flags&=~DCACHE_INOTIFY_PARENT_WATCHED;
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}
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spin_unlock(&child->d_lock);
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}
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}
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spin_unlock(&dcache_lock);
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}
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/*
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* create_watch - creates a watch on the given device.
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*
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* Callers must hold dev->mutex. Calls inotify_dev_get_wd() so may sleep.
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* Both 'dev' and 'inode' (by way of nameidata) need to be pinned.
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*/
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static struct inotify_watch *create_watch(struct inotify_device *dev,
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u32 mask, struct inode *inode)
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{
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struct inotify_watch *watch;
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int ret;
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if (atomic_read(&dev->user->inotify_watches) >=
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inotify_max_user_watches)
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return ERR_PTR(-ENOSPC);
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watch = kmem_cache_alloc(watch_cachep, GFP_KERNEL);
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if (unlikely(!watch))
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return ERR_PTR(-ENOMEM);
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ret = inotify_dev_get_wd(dev, watch);
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if (unlikely(ret)) {
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kmem_cache_free(watch_cachep, watch);
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return ERR_PTR(ret);
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}
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dev->last_wd = watch->wd;
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watch->mask = mask;
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atomic_set(&watch->count, 0);
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INIT_LIST_HEAD(&watch->d_list);
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INIT_LIST_HEAD(&watch->i_list);
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/* save a reference to device and bump the count to make it official */
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get_inotify_dev(dev);
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watch->dev = dev;
|
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|
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/*
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* Save a reference to the inode and bump the ref count to make it
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* official. We hold a reference to nameidata, which makes this safe.
|
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*/
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watch->inode = igrab(inode);
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|
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/* bump our own count, corresponding to our entry in dev->watches */
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get_inotify_watch(watch);
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atomic_inc(&dev->user->inotify_watches);
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return watch;
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}
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|
|
/*
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* inotify_find_dev - find the watch associated with the given inode and dev
|
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*
|
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* Callers must hold inode->inotify_mutex.
|
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*/
|
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static struct inotify_watch *inode_find_dev(struct inode *inode,
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struct inotify_device *dev)
|
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{
|
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struct inotify_watch *watch;
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|
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list_for_each_entry(watch, &inode->inotify_watches, i_list) {
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if (watch->dev == dev)
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return watch;
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|
}
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|
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return NULL;
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}
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|
|
/*
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* remove_watch_no_event - remove_watch() without the IN_IGNORED event.
|
|
*/
|
|
static void remove_watch_no_event(struct inotify_watch *watch,
|
|
struct inotify_device *dev)
|
|
{
|
|
list_del(&watch->i_list);
|
|
list_del(&watch->d_list);
|
|
|
|
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);
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*
|
|
* The inode is not iput() so as to remain atomic. If the inode needs to be
|
|
* iput(), the call returns one. Otherwise, it returns zero.
|
|
*/
|
|
static void remove_watch(struct inotify_watch *watch,struct inotify_device *dev)
|
|
{
|
|
inotify_dev_queue_event(dev, watch, IN_IGNORED, 0, NULL);
|
|
remove_watch_no_event(watch, dev);
|
|
}
|
|
|
|
/* Kernel API */
|
|
|
|
/*
|
|
* inotify_d_instantiate - instantiate dcache entry for inode
|
|
*/
|
|
void inotify_d_instantiate(struct dentry *entry, struct inode *inode)
|
|
{
|
|
struct dentry *parent;
|
|
|
|
if (!inode)
|
|
return;
|
|
|
|
WARN_ON(entry->d_flags & DCACHE_INOTIFY_PARENT_WATCHED);
|
|
spin_lock(&entry->d_lock);
|
|
parent = entry->d_parent;
|
|
if (parent->d_inode && inotify_inode_watched(parent->d_inode))
|
|
entry->d_flags |= DCACHE_INOTIFY_PARENT_WATCHED;
|
|
spin_unlock(&entry->d_lock);
|
|
}
|
|
|
|
/*
|
|
* inotify_d_move - dcache entry has been moved
|
|
*/
|
|
void inotify_d_move(struct dentry *entry)
|
|
{
|
|
struct dentry *parent;
|
|
|
|
parent = entry->d_parent;
|
|
if (inotify_inode_watched(parent->d_inode))
|
|
entry->d_flags |= DCACHE_INOTIFY_PARENT_WATCHED;
|
|
else
|
|
entry->d_flags &= ~DCACHE_INOTIFY_PARENT_WATCHED;
|
|
}
|
|
|
|
/**
|
|
* inotify_inode_queue_event - queue an event to all watches on this inode
|
|
* @inode: inode event is originating from
|
|
* @mask: event mask describing this event
|
|
* @cookie: cookie for synchronization, or zero
|
|
* @name: filename, if any
|
|
*/
|
|
void inotify_inode_queue_event(struct inode *inode, u32 mask, u32 cookie,
|
|
const char *name)
|
|
{
|
|
struct inotify_watch *watch, *next;
|
|
|
|
if (!inotify_inode_watched(inode))
|
|
return;
|
|
|
|
mutex_lock(&inode->inotify_mutex);
|
|
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);
|
|
if (watch_mask & IN_ONESHOT)
|
|
remove_watch_no_event(watch, dev);
|
|
mutex_unlock(&dev->mutex);
|
|
put_inotify_watch(watch);
|
|
}
|
|
}
|
|
mutex_unlock(&inode->inotify_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(inotify_inode_queue_event);
|
|
|
|
/**
|
|
* inotify_dentry_parent_queue_event - queue an event to a dentry's parent
|
|
* @dentry: the dentry in question, we queue against this dentry's parent
|
|
* @mask: event mask describing this event
|
|
* @cookie: cookie for synchronization, or zero
|
|
* @name: filename, if any
|
|
*/
|
|
void inotify_dentry_parent_queue_event(struct dentry *dentry, u32 mask,
|
|
u32 cookie, const char *name)
|
|
{
|
|
struct dentry *parent;
|
|
struct inode *inode;
|
|
|
|
if (!(dentry->d_flags & DCACHE_INOTIFY_PARENT_WATCHED))
|
|
return;
|
|
|
|
spin_lock(&dentry->d_lock);
|
|
parent = dentry->d_parent;
|
|
inode = parent->d_inode;
|
|
|
|
if (inotify_inode_watched(inode)) {
|
|
dget(parent);
|
|
spin_unlock(&dentry->d_lock);
|
|
inotify_inode_queue_event(inode, mask, cookie, name);
|
|
dput(parent);
|
|
} else
|
|
spin_unlock(&dentry->d_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(inotify_dentry_parent_queue_event);
|
|
|
|
/**
|
|
* inotify_get_cookie - return a unique cookie for use in synchronizing events.
|
|
*/
|
|
u32 inotify_get_cookie(void)
|
|
{
|
|
return atomic_inc_return(&inotify_cookie);
|
|
}
|
|
EXPORT_SYMBOL_GPL(inotify_get_cookie);
|
|
|
|
/**
|
|
* inotify_unmount_inodes - an sb is unmounting. handle any watched inodes.
|
|
* @list: list of inodes being unmounted (sb->s_inodes)
|
|
*
|
|
* Called with inode_lock held, protecting the unmounting super block's list
|
|
* of inodes, and with iprune_mutex held, keeping shrink_icache_memory() at bay.
|
|
* We temporarily drop inode_lock, however, and CAN block.
|
|
*/
|
|
void inotify_unmount_inodes(struct list_head *list)
|
|
{
|
|
struct inode *inode, *next_i, *need_iput = NULL;
|
|
|
|
list_for_each_entry_safe(inode, next_i, list, i_sb_list) {
|
|
struct inotify_watch *watch, *next_w;
|
|
struct inode *need_iput_tmp;
|
|
struct list_head *watches;
|
|
|
|
/*
|
|
* If i_count is zero, the inode cannot have any watches and
|
|
* doing an __iget/iput with MS_ACTIVE clear would actually
|
|
* evict all inodes with zero i_count from icache which is
|
|
* unnecessarily violent and may in fact be illegal to do.
|
|
*/
|
|
if (!atomic_read(&inode->i_count))
|
|
continue;
|
|
|
|
/*
|
|
* We cannot __iget() an inode in state I_CLEAR, I_FREEING, or
|
|
* I_WILL_FREE which is fine because by that point the inode
|
|
* cannot have any associated watches.
|
|
*/
|
|
if (inode->i_state & (I_CLEAR | I_FREEING | I_WILL_FREE))
|
|
continue;
|
|
|
|
need_iput_tmp = need_iput;
|
|
need_iput = NULL;
|
|
/* In case the remove_watch() drops a reference. */
|
|
if (inode != need_iput_tmp)
|
|
__iget(inode);
|
|
else
|
|
need_iput_tmp = NULL;
|
|
/* In case the dropping of a reference would nuke next_i. */
|
|
if ((&next_i->i_sb_list != list) &&
|
|
atomic_read(&next_i->i_count) &&
|
|
!(next_i->i_state & (I_CLEAR | I_FREEING |
|
|
I_WILL_FREE))) {
|
|
__iget(next_i);
|
|
need_iput = next_i;
|
|
}
|
|
|
|
/*
|
|
* We can safely drop inode_lock here because we hold
|
|
* references on both inode and next_i. Also no new inodes
|
|
* will be added since the umount has begun. Finally,
|
|
* iprune_mutex keeps shrink_icache_memory() away.
|
|
*/
|
|
spin_unlock(&inode_lock);
|
|
|
|
if (need_iput_tmp)
|
|
iput(need_iput_tmp);
|
|
|
|
/* for each watch, send IN_UNMOUNT and then remove it */
|
|
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);
|
|
}
|
|
mutex_unlock(&inode->inotify_mutex);
|
|
iput(inode);
|
|
|
|
spin_lock(&inode_lock);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(inotify_unmount_inodes);
|
|
|
|
/**
|
|
* inotify_inode_is_dead - an inode has been deleted, cleanup any watches
|
|
* @inode: inode that is about to be removed
|
|
*/
|
|
void inotify_inode_is_dead(struct inode *inode)
|
|
{
|
|
struct inotify_watch *watch, *next;
|
|
|
|
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);
|
|
}
|
|
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;
|
|
}
|
|
|
|
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->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;
|
|
}
|
|
|
|
remove_kevent(dev, kevent);
|
|
}
|
|
mutex_unlock(&dev->mutex);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int inotify_release(struct inode *ignored, struct file *file)
|
|
{
|
|
struct inotify_device *dev = file->private_data;
|
|
|
|
/*
|
|
* Destroy all of the watches on this device. Unfortunately, not very
|
|
* pretty. We cannot do a simple iteration over the list, because we
|
|
* do not know the inode until we iterate to the watch. But we need to
|
|
* hold inode->inotify_mutex before dev->mutex. The following works.
|
|
*/
|
|
while (1) {
|
|
struct inotify_watch *watch;
|
|
struct list_head *watches;
|
|
struct inode *inode;
|
|
|
|
mutex_lock(&dev->mutex);
|
|
watches = &dev->watches;
|
|
if (list_empty(watches)) {
|
|
mutex_unlock(&dev->mutex);
|
|
break;
|
|
}
|
|
watch = list_entry(watches->next, struct inotify_watch, d_list);
|
|
get_inotify_watch(watch);
|
|
mutex_unlock(&dev->mutex);
|
|
|
|
inode = watch->inode;
|
|
mutex_lock(&inode->inotify_mutex);
|
|
mutex_lock(&dev->mutex);
|
|
remove_watch_no_event(watch, dev);
|
|
mutex_unlock(&dev->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;
|
|
}
|
|
|
|
/*
|
|
* inotify_ignore - remove a given wd from this inotify instance.
|
|
*
|
|
* Can sleep.
|
|
*/
|
|
static int inotify_ignore(struct inotify_device *dev, s32 wd)
|
|
{
|
|
struct inotify_watch *watch;
|
|
struct inode *inode;
|
|
|
|
mutex_lock(&dev->mutex);
|
|
watch = idr_find(&dev->idr, wd);
|
|
if (unlikely(!watch)) {
|
|
mutex_unlock(&dev->mutex);
|
|
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 */
|
|
watch = idr_find(&dev->idr, wd);
|
|
if (likely(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;
|
|
|
|
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;
|
|
}
|
|
|
|
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);
|
|
return ret;
|
|
}
|
|
|
|
asmlinkage long sys_inotify_add_watch(int fd, const char __user *path, u32 mask)
|
|
{
|
|
struct inotify_watch *watch, *old;
|
|
struct inode *inode;
|
|
struct inotify_device *dev;
|
|
struct nameidata nd;
|
|
struct file *filp;
|
|
int ret, fput_needed;
|
|
int mask_add = 0;
|
|
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(&inode->inotify_mutex);
|
|
mutex_lock(&dev->mutex);
|
|
|
|
if (mask & IN_MASK_ADD)
|
|
mask_add = 1;
|
|
|
|
/* 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;
|
|
}
|
|
|
|
/*
|
|
* Handle the case of re-adding a watch on an (inode,dev) pair that we
|
|
* are already watching. We just update the mask and return its wd.
|
|
*/
|
|
old = inode_find_dev(inode, dev);
|
|
if (unlikely(old)) {
|
|
if (mask_add)
|
|
old->mask |= mask;
|
|
else
|
|
old->mask = mask;
|
|
ret = old->wd;
|
|
goto out;
|
|
}
|
|
|
|
watch = create_watch(dev, mask, inode);
|
|
if (unlikely(IS_ERR(watch))) {
|
|
ret = PTR_ERR(watch);
|
|
goto out;
|
|
}
|
|
|
|
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);
|
|
list_add(&watch->i_list, &inode->inotify_watches);
|
|
ret = watch->wd;
|
|
out:
|
|
mutex_unlock(&dev->mutex);
|
|
mutex_unlock(&inode->inotify_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;
|
|
ret = inotify_ignore(dev, wd);
|
|
|
|
out:
|
|
fput_light(filp, fput_needed);
|
|
return ret;
|
|
}
|
|
|
|
static struct super_block *
|
|
inotify_get_sb(struct file_system_type *fs_type, int flags,
|
|
const char *dev_name, void *data)
|
|
{
|
|
return get_sb_pseudo(fs_type, "inotify", NULL, 0xBAD1DEA);
|
|
}
|
|
|
|
static struct file_system_type inotify_fs_type = {
|
|
.name = "inotifyfs",
|
|
.get_sb = inotify_get_sb,
|
|
.kill_sb = kill_anon_super,
|
|
};
|
|
|
|
/*
|
|
* inotify_setup - Our initialization function. Note that we cannnot return
|
|
* error because we have compiled-in VFS hooks. So an (unlikely) failure here
|
|
* must result in panic().
|
|
*/
|
|
static int __init inotify_setup(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = register_filesystem(&inotify_fs_type);
|
|
if (unlikely(ret))
|
|
panic("inotify: register_filesystem returned %d!\n", ret);
|
|
|
|
inotify_mnt = kern_mount(&inotify_fs_type);
|
|
if (IS_ERR(inotify_mnt))
|
|
panic("inotify: kern_mount ret %ld!\n", PTR_ERR(inotify_mnt));
|
|
|
|
inotify_max_queued_events = 16384;
|
|
inotify_max_user_instances = 128;
|
|
inotify_max_user_watches = 8192;
|
|
|
|
atomic_set(&inotify_cookie, 0);
|
|
|
|
watch_cachep = kmem_cache_create("inotify_watch_cache",
|
|
sizeof(struct inotify_watch),
|
|
0, SLAB_PANIC, NULL, NULL);
|
|
event_cachep = kmem_cache_create("inotify_event_cache",
|
|
sizeof(struct inotify_kernel_event),
|
|
0, SLAB_PANIC, NULL, NULL);
|
|
|
|
return 0;
|
|
}
|
|
|
|
module_init(inotify_setup);
|