diff options
Diffstat (limited to 'fs/inotify.c')
| -rw-r--r-- | fs/inotify.c | 911 |
1 files changed, 0 insertions, 911 deletions
diff --git a/fs/inotify.c b/fs/inotify.c deleted file mode 100644 index 7bbed1b89825..000000000000 --- a/fs/inotify.c +++ /dev/null @@ -1,911 +0,0 @@ -/* - * fs/inotify.c - inode-based file event notifications - * - * Authors: - * 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 - * Free Software Foundation; either version 2, or (at your option) any - * later version. - * - * This program is distributed in the hope that it will be useful, but - * WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * General Public License for more details. - */ - -#include <linux/module.h> -#include <linux/kernel.h> -#include <linux/spinlock.h> -#include <linux/idr.h> -#include <linux/slab.h> -#include <linux/fs.h> -#include <linux/sched.h> -#include <linux/init.h> -#include <linux/list.h> -#include <linux/writeback.h> -#include <linux/inotify.h> - -static atomic_t inotify_cookie; - -/* - * Lock ordering: - * - * dentry->d_lock (used to keep d_move() away from dentry->d_parent) - * 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_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_handle, inode, and - * inotify_watch--are managed by reference count. - * - * 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: 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 - * inotify_add_watch() to the final put_inotify_watch(). - */ - -/* - * struct inotify_handle - represents an inotify instance - * - * This structure is protected by the mutex 'mutex'. - */ -struct inotify_handle { - struct idr idr; /* idr mapping wd -> watch */ - struct mutex mutex; /* protects this bad boy */ - struct list_head watches; /* list of watches */ - atomic_t count; /* reference count */ - u32 last_wd; /* the last wd allocated */ - const struct inotify_operations *in_ops; /* inotify caller operations */ -}; - -static inline void get_inotify_handle(struct inotify_handle *ih) -{ - atomic_inc(&ih->count); -} - -static inline void put_inotify_handle(struct inotify_handle *ih) -{ - if (atomic_dec_and_test(&ih->count)) { - idr_destroy(&ih->idr); - kfree(ih); - } -} - -/** - * 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); - -int pin_inotify_watch(struct inotify_watch *watch) -{ - struct super_block *sb = watch->inode->i_sb; - spin_lock(&sb_lock); - if (sb->s_count >= S_BIAS) { - atomic_inc(&sb->s_active); - spin_unlock(&sb_lock); - atomic_inc(&watch->count); - return 1; - } - spin_unlock(&sb_lock); - return 0; -} - -/** - * put_inotify_watch - decrements the ref count on a given watch. cleans up - * watch references if the count reaches zero. inotify_watch is freed by - * inotify callers via the destroy_watch() op. - * @watch: watch to release - */ -void put_inotify_watch(struct inotify_watch *watch) -{ - if (atomic_dec_and_test(&watch->count)) { - struct inotify_handle *ih = watch->ih; - - iput(watch->inode); - ih->in_ops->destroy_watch(watch); - put_inotify_handle(ih); - } -} -EXPORT_SYMBOL_GPL(put_inotify_watch); - -void unpin_inotify_watch(struct inotify_watch *watch) -{ - struct super_block *sb = watch->inode->i_sb; - put_inotify_watch(watch); - deactivate_super(sb); -} - -/* - * inotify_handle_get_wd - returns the next WD for use by the given handle - * - * Callers must hold ih->mutex. This function can sleep. - */ -static int inotify_handle_get_wd(struct inotify_handle *ih, - struct inotify_watch *watch) -{ - int ret; - - do { - if (unlikely(!idr_pre_get(&ih->idr, GFP_KERNEL))) - return -ENOSPC; - ret = idr_get_new_above(&ih->idr, watch, ih->last_wd+1, &watch->wd); - } while (ret == -EAGAIN); - - if (likely(!ret)) - ih->last_wd = watch->wd; - - return ret; -} - -/* - * inotify_inode_watched - returns nonzero if there are watches on this inode - * and zero otherwise. We call this lockless, we do not care if we race. - */ -static inline int inotify_inode_watched(struct inode *inode) -{ - return !list_empty(&inode->inotify_watches); -} - -/* - * Get child dentry flag into synch with parent inode. - * Flag should always be clear for negative dentrys. - */ -static void set_dentry_child_flags(struct inode *inode, int watched) -{ - struct dentry *alias; - - spin_lock(&dcache_lock); - list_for_each_entry(alias, &inode->i_dentry, d_alias) { - struct dentry *child; - - list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) { - if (!child->d_inode) - continue; - - spin_lock(&child->d_lock); - if (watched) - child->d_flags |= DCACHE_INOTIFY_PARENT_WATCHED; - else - child->d_flags &=~DCACHE_INOTIFY_PARENT_WATCHED; - spin_unlock(&child->d_lock); - } - } - spin_unlock(&dcache_lock); -} - -/* - * 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_handle(struct inode *inode, - struct inotify_handle *ih) -{ - struct inotify_watch *watch; - - list_for_each_entry(watch, &inode->inotify_watches, i_list) { - if (watch->ih == ih) - return watch; - } - - return NULL; -} - -/* - * 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_handle *ih) -{ - list_del(&watch->i_list); - list_del(&watch->h_list); - - if (!inotify_inode_watched(watch->inode)) - set_dentry_child_flags(watch->inode, 0); - - idr_remove(&ih->idr, watch->wd); -} - -/** - * inotify_remove_watch_locked - Remove a watch from both the handle and the - * inode. Sends the IN_IGNORED event signifying that the inode is no longer - * watched. May be invoked from a caller's event handler. - * @ih: inotify handle associated with watch - * @watch: watch to remove - * - * Callers must hold both inode->inotify_mutex and ih->mutex. - */ -void inotify_remove_watch_locked(struct inotify_handle *ih, - struct inotify_watch *watch) -{ - remove_watch_no_event(watch, ih); - ih->in_ops->handle_event(watch, watch->wd, IN_IGNORED, 0, NULL, NULL); -} -EXPORT_SYMBOL_GPL(inotify_remove_watch_locked); - -/* Kernel API for producing events */ - -/* - * inotify_d_instantiate - instantiate dcache entry for inode - */ -void inotify_d_instantiate(struct dentry *entry, struct inode *inode) -{ - struct dentry *parent; - - if (!inode) - return; - - 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 - * @n_inode: inode associated with name - */ -void inotify_inode_queue_event(struct inode *inode, u32 mask, u32 cookie, - const char *name, struct inode *n_inode) -{ - 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_handle *ih= watch->ih; - mutex_lock(&ih->mutex); - if (watch_mask & IN_ONESHOT) - remove_watch_no_event(watch, ih); - ih->in_ops->handle_event(watch, watch->wd, mask, cookie, - name, n_inode); - mutex_unlock(&ih->mutex); - } - } - 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, - dentry->d_inode); - 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 inotify_remove_watch_locked() 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_handle *ih= watch->ih; - mutex_lock(&ih->mutex); - ih->in_ops->handle_event(watch, watch->wd, IN_UNMOUNT, 0, - NULL, NULL); - inotify_remove_watch_locked(ih, watch); - mutex_unlock(&ih->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_handle *ih = watch->ih; - mutex_lock(&ih->mutex); - inotify_remove_watch_locked(ih, watch); - mutex_unlock(&ih->mutex); - } - mutex_unlock(&inode->inotify_mutex); -} -EXPORT_SYMBOL_GPL(inotify_inode_is_dead); - -/* Kernel Consumer API */ - -/** - * inotify_init - allocate and initialize an inotify instance - * @ops: caller's inotify operations - */ -struct inotify_handle *inotify_init(const struct inotify_operations *ops) -{ - struct inotify_handle *ih; - - ih = kmalloc(sizeof(struct inotify_handle), GFP_KERNEL); - if (unlikely(!ih)) - return ERR_PTR(-ENOMEM); - - 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 ih; -} -EXPORT_SYMBOL_GPL(inotify_init); - -/** - * inotify_init_watch - initialize an inotify watch - * @watch: watch to initialize - */ -void inotify_init_watch(struct inotify_watch *watch) -{ - INIT_LIST_HEAD(&watch->h_list); - INIT_LIST_HEAD(&watch->i_list); - atomic_set(&watch->count, 0); - get_inotify_watch(watch); /* initial get */ -} -EXPORT_SYMBOL_GPL(inotify_init_watch); - -/* - * Watch removals suck violently. To kick the watch out we need (in this - * order) inode->inotify_mutex and ih->mutex. That's fine if we have - * a hold on inode; however, for all other cases we need to make damn sure - * we don't race with umount. We can *NOT* just grab a reference to a - * watch - inotify_unmount_inodes() will happily sail past it and we'll end - * with reference to inode potentially outliving its superblock. Ideally - * we just want to grab an active reference to superblock if we can; that - * will make sure we won't go into inotify_umount_inodes() until we are - * done. Cleanup is just deactivate_super(). However, that leaves a messy - * case - what if we *are* racing with umount() and active references to - * superblock can't be acquired anymore? We can bump ->s_count, grab - * ->s_umount, which will almost certainly wait until the superblock is shut - * down and the watch in question is pining for fjords. That's fine, but - * there is a problem - we might have hit the window between ->s_active - * getting to 0 / ->s_count - below S_BIAS (i.e. the moment when superblock - * is past the point of no return and is heading for shutdown) and the - * moment when deactivate_super() acquires ->s_umount. We could just do - * drop_super() yield() and retry, but that's rather antisocial and this - * stuff is luser-triggerable. OTOH, having grabbed ->s_umount and having - * found that we'd got there first (i.e. that ->s_root is non-NULL) we know - * that we won't race with inotify_umount_inodes(). So we could grab a - * reference to watch and do the rest as above, just with drop_super() instead - * of deactivate_super(), right? Wrong. We had to drop ih->mutex before we - * could grab ->s_umount. So the watch could've been gone already. - * - * That still can be dealt with - we need to save watch->wd, do idr_find() - * and compare its result with our pointer. If they match, we either have - * the damn thing still alive or we'd lost not one but two races at once, - * the watch had been killed and a new one got created with the same ->wd - * at the same address. That couldn't have happened in inotify_destroy(), - * but inotify_rm_wd() could run into that. Still, "new one got created" - * is not a problem - we have every right to kill it or leave it alone, - * whatever's more convenient. - * - * So we can use idr_find(...) == watch && watch->inode->i_sb == sb as - * "grab it and kill it" check. If it's been our original watch, we are - * fine, if it's a newcomer - nevermind, just pretend that we'd won the - * race and kill the fscker anyway; we are safe since we know that its - * superblock won't be going away. - * - * And yes, this is far beyond mere "not very pretty"; so's the entire - * concept of inotify to start with. - */ - -/** - * pin_to_kill - pin the watch down for removal - * @ih: inotify handle - * @watch: watch to kill - * - * Called with ih->mutex held, drops it. Possible return values: - * 0 - nothing to do, it has died - * 1 - remove it, drop the reference and deactivate_super() - * 2 - remove it, drop the reference and drop_super(); we tried hard to avoid - * that variant, since it involved a lot of PITA, but that's the best that - * could've been done. - */ -static int pin_to_kill(struct inotify_handle *ih, struct inotify_watch *watch) -{ - struct super_block *sb = watch->inode->i_sb; - s32 wd = watch->wd; - - spin_lock(&sb_lock); - if (sb->s_count >= S_BIAS) { - atomic_inc(&sb->s_active); - spin_unlock(&sb_lock); - get_inotify_watch(watch); - mutex_unlock(&ih->mutex); - return 1; /* the best outcome */ - } - sb->s_count++; - spin_unlock(&sb_lock); - mutex_unlock(&ih->mutex); /* can't grab ->s_umount under it */ - down_read(&sb->s_umount); - if (likely(!sb->s_root)) { - /* fs is already shut down; the watch is dead */ - drop_super(sb); - return 0; - } - /* raced with the final deactivate_super() */ - mutex_lock(&ih->mutex); - if (idr_find(&ih->idr, wd) != watch || watch->inode->i_sb != sb) { - /* the watch is dead */ - mutex_unlock(&ih->mutex); - drop_super(sb); - return 0; - } - /* still alive or freed and reused with the same sb and wd; kill */ - get_inotify_watch(watch); - mutex_unlock(&ih->mutex); - return 2; -} - -static void unpin_and_kill(struct inotify_watch *watch, int how) -{ - struct super_block *sb = watch->inode->i_sb; - put_inotify_watch(watch); - switch (how) { - case 1: - deactivate_super(sb); - break; - case 2: - drop_super(sb); - } -} - -/** - * inotify_destroy - clean up and destroy an inotify instance - * @ih: inotify handle - */ -void inotify_destroy(struct inotify_handle *ih) -{ - /* - * 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 ih->mutex. The following works. - * - * AV: it had to become even uglier to start working ;-/ - */ - while (1) { - struct inotify_watch *watch; - struct list_head *watches; - struct super_block *sb; - struct inode *inode; - int how; - - mutex_lock(&ih->mutex); - watches = &ih->watches; - if (list_empty(watches)) { - mutex_unlock(&ih->mutex); - break; - } - watch = list_first_entry(watches, struct inotify_watch, h_list); - sb = watch->inode->i_sb; - how = pin_to_kill(ih, watch); - if (!how) - continue; - - inode = watch->inode; - mutex_lock(&inode->inotify_mutex); - mutex_lock(&ih->mutex); - - /* make sure we didn't race with another list removal */ - if (likely(idr_find(&ih->idr, watch->wd))) { - remove_watch_no_event(watch, ih); - put_inotify_watch(watch); - } - - mutex_unlock(&ih->mutex); - mutex_unlock(&inode->inotify_mutex); - unpin_and_kill(watch, how); - } - - /* free this handle: the put matching the get in inotify_init() */ - put_inotify_handle(ih); -} -EXPORT_SYMBOL_GPL(inotify_destroy); - -/** - * inotify_find_watch - find an existing watch for an (ih,inode) pair - * @ih: inotify handle - * @inode: inode to watch - * @watchp: pointer to existing inotify_watch - * - * Caller must pin given inode (via nameidata). - */ -s32 inotify_find_watch(struct inotify_handle *ih, struct inode *inode, - struct inotify_watch **watchp) -{ - struct inotify_watch *old; - int ret = -ENOENT; - - mutex_lock(&inode->inotify_mutex); - mutex_lock(&ih->mutex); - - old = inode_find_handle(inode, ih); - if (unlikely(old)) { - get_inotify_watch(old); /* caller must put watch */ - *watchp = old; - ret = old->wd; - } - - mutex_unlock(&ih->mutex); - mutex_unlock(&inode->inotify_mutex); - - return ret; -} -EXPORT_SYMBOL_GPL(inotify_find_watch); - -/** - * 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 - * - * Caller must pin given inode (via nameidata). - */ -s32 inotify_find_update_watch(struct inotify_handle *ih, struct inode *inode, - u32 mask) -{ - struct inotify_watch *old; - int mask_add = 0; - int ret; - - 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; - - mutex_lock(&inode->inotify_mutex); - mutex_lock(&ih->mutex); - - /* - * 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; - } - - 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); - -/** - * 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) -{ - int ret = 0; - int newly_watched; - - /* 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; - - mutex_lock(&inode->inotify_mutex); - mutex_lock(&ih->mutex); - - /* Initialize a new watch */ - ret = inotify_handle_get_wd(ih, watch); - if (unlikely(ret)) - goto out; - ret = watch->wd; - - /* save a reference to handle and bump the count to make it official */ - get_inotify_handle(ih); - watch->ih = ih; - - /* - * 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); - - /* Add the watch to the handle's and the inode's list */ - newly_watched = !inotify_inode_watched(inode); - list_add(&watch->h_list, &ih->watches); - list_add(&watch->i_list, &inode->inotify_watches); - /* - * Set child flags _after_ adding the watch, so there is no race - * windows where newly instantiated children could miss their parent's - * watched flag. - */ - if (newly_watched) - set_dentry_child_flags(inode, 1); - -out: - mutex_unlock(&ih->mutex); - mutex_unlock(&inode->inotify_mutex); - return ret; -} -EXPORT_SYMBOL_GPL(inotify_add_watch); - -/** - * inotify_clone_watch - put the watch next to existing one - * @old: already installed watch - * @new: new watch - * - * Caller must hold the inotify_mutex of inode we are dealing with; - * it is expected to remove the old watch before unlocking the inode. - */ -s32 inotify_clone_watch(struct inotify_watch *old, struct inotify_watch *new) -{ - struct inotify_handle *ih = old->ih; - int ret = 0; - - new->mask = old->mask; - new->ih = ih; - - mutex_lock(&ih->mutex); - - /* Initialize a new watch */ - ret = inotify_handle_get_wd(ih, new); - if (unlikely(ret)) - goto out; - ret = new->wd; - - get_inotify_handle(ih); - - new->inode = igrab(old->inode); - - list_add(&new->h_list, &ih->watches); - list_add(&new->i_list, &old->inode->inotify_watches); -out: - mutex_unlock(&ih->mutex); - return ret; -} - -void inotify_evict_watch(struct inotify_watch *watch) -{ - get_inotify_watch(watch); - mutex_lock(&watch->ih->mutex); - inotify_remove_watch_locked(watch->ih, watch); - mutex_unlock(&watch->ih->mutex); -} - -/** - * 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 inotify_watch *watch; - struct super_block *sb; - struct inode *inode; - int how; - - mutex_lock(&ih->mutex); - watch = idr_find(&ih->idr, wd); - if (unlikely(!watch)) { - mutex_unlock(&ih->mutex); - return -EINVAL; - } - sb = watch->inode->i_sb; - how = pin_to_kill(ih, watch); - if (!how) - return 0; - - inode = watch->inode; - - mutex_lock(&inode->inotify_mutex); - mutex_lock(&ih->mutex); - - /* make sure that we did not race */ - if (likely(idr_find(&ih->idr, wd) == watch)) - inotify_remove_watch_locked(ih, watch); - - mutex_unlock(&ih->mutex); - mutex_unlock(&inode->inotify_mutex); - unpin_and_kill(watch, how); - - return 0; -} -EXPORT_SYMBOL_GPL(inotify_rm_wd); - -/** - * inotify_rm_watch - remove a watch from an inotify instance - * @ih: inotify handle - * @watch: watch to remove - * - * Can sleep. - */ -int inotify_rm_watch(struct inotify_handle *ih, - struct inotify_watch *watch) -{ - return inotify_rm_wd(ih, watch->wd); -} -EXPORT_SYMBOL_GPL(inotify_rm_watch); - -/* - * inotify_setup - core initialization function - */ -static int __init inotify_setup(void) -{ - atomic_set(&inotify_cookie, 0); - - return 0; -} - -module_init(inotify_setup); |