diff options
Diffstat (limited to 'fs/notify')
| -rw-r--r-- | fs/notify/Kconfig | 2 | ||||
| -rw-r--r-- | fs/notify/Makefile | 2 | ||||
| -rw-r--r-- | fs/notify/dnotify/Kconfig | 10 | ||||
| -rw-r--r-- | fs/notify/dnotify/Makefile | 1 | ||||
| -rw-r--r-- | fs/notify/dnotify/dnotify.c | 191 | ||||
| -rw-r--r-- | fs/notify/inotify/Kconfig | 27 | ||||
| -rw-r--r-- | fs/notify/inotify/Makefile | 2 | ||||
| -rw-r--r-- | fs/notify/inotify/inotify.c | 913 | ||||
| -rw-r--r-- | fs/notify/inotify/inotify_user.c | 779 |
9 files changed, 1927 insertions, 0 deletions
diff --git a/fs/notify/Kconfig b/fs/notify/Kconfig new file mode 100644 index 00000000000..50914d7303c --- /dev/null +++ b/fs/notify/Kconfig @@ -0,0 +1,2 @@ +source "fs/notify/dnotify/Kconfig" +source "fs/notify/inotify/Kconfig" diff --git a/fs/notify/Makefile b/fs/notify/Makefile new file mode 100644 index 00000000000..5a95b6010ce --- /dev/null +++ b/fs/notify/Makefile @@ -0,0 +1,2 @@ +obj-y += dnotify/ +obj-y += inotify/ diff --git a/fs/notify/dnotify/Kconfig b/fs/notify/dnotify/Kconfig new file mode 100644 index 00000000000..26adf5dfa64 --- /dev/null +++ b/fs/notify/dnotify/Kconfig @@ -0,0 +1,10 @@ +config DNOTIFY + bool "Dnotify support" + default y + help + Dnotify is a directory-based per-fd file change notification system + that uses signals to communicate events to user-space. There exist + superior alternatives, but some applications may still rely on + dnotify. + + If unsure, say Y. diff --git a/fs/notify/dnotify/Makefile b/fs/notify/dnotify/Makefile new file mode 100644 index 00000000000..f145251dcad --- /dev/null +++ b/fs/notify/dnotify/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_DNOTIFY) += dnotify.o diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c new file mode 100644 index 00000000000..b0aa2cde80b --- /dev/null +++ b/fs/notify/dnotify/dnotify.c @@ -0,0 +1,191 @@ +/* + * Directory notifications for Linux. + * + * Copyright (C) 2000,2001,2002 Stephen Rothwell + * + * 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/fs.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/dnotify.h> +#include <linux/init.h> +#include <linux/spinlock.h> +#include <linux/slab.h> +#include <linux/fdtable.h> + +int dir_notify_enable __read_mostly = 1; + +static struct kmem_cache *dn_cache __read_mostly; + +static void redo_inode_mask(struct inode *inode) +{ + unsigned long new_mask; + struct dnotify_struct *dn; + + new_mask = 0; + for (dn = inode->i_dnotify; dn != NULL; dn = dn->dn_next) + new_mask |= dn->dn_mask & ~DN_MULTISHOT; + inode->i_dnotify_mask = new_mask; +} + +void dnotify_flush(struct file *filp, fl_owner_t id) +{ + struct dnotify_struct *dn; + struct dnotify_struct **prev; + struct inode *inode; + + inode = filp->f_path.dentry->d_inode; + if (!S_ISDIR(inode->i_mode)) + return; + spin_lock(&inode->i_lock); + prev = &inode->i_dnotify; + while ((dn = *prev) != NULL) { + if ((dn->dn_owner == id) && (dn->dn_filp == filp)) { + *prev = dn->dn_next; + redo_inode_mask(inode); + kmem_cache_free(dn_cache, dn); + break; + } + prev = &dn->dn_next; + } + spin_unlock(&inode->i_lock); +} + +int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) +{ + struct dnotify_struct *dn; + struct dnotify_struct *odn; + struct dnotify_struct **prev; + struct inode *inode; + fl_owner_t id = current->files; + struct file *f; + int error = 0; + + if ((arg & ~DN_MULTISHOT) == 0) { + dnotify_flush(filp, id); + return 0; + } + if (!dir_notify_enable) + return -EINVAL; + inode = filp->f_path.dentry->d_inode; + if (!S_ISDIR(inode->i_mode)) + return -ENOTDIR; + dn = kmem_cache_alloc(dn_cache, GFP_KERNEL); + if (dn == NULL) + return -ENOMEM; + spin_lock(&inode->i_lock); + prev = &inode->i_dnotify; + while ((odn = *prev) != NULL) { + if ((odn->dn_owner == id) && (odn->dn_filp == filp)) { + odn->dn_fd = fd; + odn->dn_mask |= arg; + inode->i_dnotify_mask |= arg & ~DN_MULTISHOT; + goto out_free; + } + prev = &odn->dn_next; + } + + rcu_read_lock(); + f = fcheck(fd); + rcu_read_unlock(); + /* we'd lost the race with close(), sod off silently */ + /* note that inode->i_lock prevents reordering problems + * between accesses to descriptor table and ->i_dnotify */ + if (f != filp) + goto out_free; + + error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); + if (error) + goto out_free; + + dn->dn_mask = arg; + dn->dn_fd = fd; + dn->dn_filp = filp; + dn->dn_owner = id; + inode->i_dnotify_mask |= arg & ~DN_MULTISHOT; + dn->dn_next = inode->i_dnotify; + inode->i_dnotify = dn; + spin_unlock(&inode->i_lock); + return 0; + +out_free: + spin_unlock(&inode->i_lock); + kmem_cache_free(dn_cache, dn); + return error; +} + +void __inode_dir_notify(struct inode *inode, unsigned long event) +{ + struct dnotify_struct * dn; + struct dnotify_struct **prev; + struct fown_struct * fown; + int changed = 0; + + spin_lock(&inode->i_lock); + prev = &inode->i_dnotify; + while ((dn = *prev) != NULL) { + if ((dn->dn_mask & event) == 0) { + prev = &dn->dn_next; + continue; + } + fown = &dn->dn_filp->f_owner; + send_sigio(fown, dn->dn_fd, POLL_MSG); + if (dn->dn_mask & DN_MULTISHOT) + prev = &dn->dn_next; + else { + *prev = dn->dn_next; + changed = 1; + kmem_cache_free(dn_cache, dn); + } + } + if (changed) + redo_inode_mask(inode); + spin_unlock(&inode->i_lock); +} + +EXPORT_SYMBOL(__inode_dir_notify); + +/* + * This is hopelessly wrong, but unfixable without API changes. At + * least it doesn't oops the kernel... + * + * To safely access ->d_parent we need to keep d_move away from it. Use the + * dentry's d_lock for this. + */ +void dnotify_parent(struct dentry *dentry, unsigned long event) +{ + struct dentry *parent; + + if (!dir_notify_enable) + return; + + spin_lock(&dentry->d_lock); + parent = dentry->d_parent; + if (parent->d_inode->i_dnotify_mask & event) { + dget(parent); + spin_unlock(&dentry->d_lock); + __inode_dir_notify(parent->d_inode, event); + dput(parent); + } else { + spin_unlock(&dentry->d_lock); + } +} +EXPORT_SYMBOL_GPL(dnotify_parent); + +static int __init dnotify_init(void) +{ + dn_cache = kmem_cache_create("dnotify_cache", + sizeof(struct dnotify_struct), 0, SLAB_PANIC, NULL); + return 0; +} + +module_init(dnotify_init) diff --git a/fs/notify/inotify/Kconfig b/fs/notify/inotify/Kconfig new file mode 100644 index 00000000000..44679284102 --- /dev/null +++ b/fs/notify/inotify/Kconfig @@ -0,0 +1,27 @@ +config INOTIFY + bool "Inotify file change notification support" + default y + ---help--- + 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 <file: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 <file:Documentation/filesystems/inotify.txt> + + If unsure, say Y. diff --git a/fs/notify/inotify/Makefile b/fs/notify/inotify/Makefile new file mode 100644 index 00000000000..e290f3bb9d8 --- /dev/null +++ b/fs/notify/inotify/Makefile @@ -0,0 +1,2 @@ +obj-$(CONFIG_INOTIFY) += inotify.o +obj-$(CONFIG_INOTIFY_USER) += inotify_user.o diff --git a/fs/notify/inotify/inotify.c b/fs/notify/inotify/inotify.c new file mode 100644 index 00000000000..dae3f28f30d --- /dev/null +++ b/fs/notify/inotify/inotify.c @@ -0,0 +1,913 @@ +/* + * 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; + get_inotify_watch(watch); + 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); + put_inotify_watch(watch); + } + 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); diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c new file mode 100644 index 00000000000..d53a1838d6e --- /dev/null +++ b/fs/notify/inotify/inotify_user.c @@ -0,0 +1,779 @@ +/* + * 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 <linux/magic.h> + +#include <asm/ioctls.h> + +static struct kmem_cache *watch_cachep __read_mostly; +static struct kmem_cache *event_cachep __read_mostly; + +static struct vfsmount *inotify_mnt __read_mostly; + +/* these are configurable via /proc/sys/fs/inotify/ */ +static int inotify_max_user_instances __read_mostly; +static int inotify_max_user_watches __read_mostly; +static 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 */ + struct user_struct *user; /* user who opened this dev */ + struct inotify_handle *ih; /* inotify handle */ + struct fasync_struct *fa; /* async notification */ + atomic_t count; /* reference count */ + 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_NOFS); + 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_get_last_event - return the last event in the given dev's queue + * + * Caller must hold dev->ev_mutex. + */ +static inline struct inotify_kernel_event * +inotify_dev_get_last_event(struct inotify_device *dev) +{ + if (list_empty(&dev->events)) + return NULL; + return list_entry(dev->events.prev, 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 inode *ignored) +{ + 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 || w->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_last_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); + kill_fasync(&dev->fa, SIGIO, POLL_IN); + +out: + mutex_unlock(&dev->ev_mutex); +} + +/* + * remove_kevent - cleans up 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; +} + +/* + * free_kevent - frees the given kevent. + */ +static void free_kevent(struct inotify_kernel_event *kevent) +{ + 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); + free_kevent(kevent); + } +} + +/* + * find_inode - resolve a user-given path to a specific inode + */ +static int find_inode(const char __user *dirname, struct path *path, + unsigned flags) +{ + int error; + + error = user_path_at(AT_FDCWD, dirname, flags, path); + if (error) + return error; + /* you can only watch an inode if you have read permissions on it */ + error = inode_permission(path->dentry->d_inode, MAY_READ); + if (error) + path_put(path); + 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); + + inotify_init_watch(&watch->wdata); + 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) { + + prepare_to_wait(&dev->wq, &wait, TASK_INTERRUPTIBLE); + + mutex_lock(&dev->ev_mutex); + if (!list_empty(&dev->events)) { + ret = 0; + break; + } + mutex_unlock(&dev->ev_mutex); + + 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; + + 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) { + if (ret == 0 && count > 0) { + /* + * could not get a single event because we + * didn't have enough buffer space. + */ + ret = -EINVAL; + } + break; + } + remove_kevent(dev, kevent); + + /* + * Must perform the copy_to_user outside the mutex in order + * to avoid a lock order reversal with mmap_sem. + */ + mutex_unlock(&dev->ev_mutex); + + 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; + } + + free_kevent(kevent); + + mutex_lock(&dev->ev_mutex); + } + mutex_unlock(&dev->ev_mutex); + + return ret; +} + +static int inotify_fasync(int fd, struct file *file, int on) +{ + struct inotify_device *dev = file->private_data; + + return fasync_helper(fd, file, on, &dev->fa) >= 0 ? 0 : -EIO; +} + +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, + .fasync = inotify_fasync, + .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, +}; + +SYSCALL_DEFINE1(inotify_init1, int, flags) +{ + struct inotify_device *dev; + struct inotify_handle *ih; + struct user_struct *user; + struct file *filp; + int fd, ret; + + /* Check the IN_* constants for consistency. */ + BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC); + BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK); + + if (flags & ~(IN_CLOEXEC | IN_NONBLOCK)) + return -EINVAL; + + fd = get_unused_fd_flags(flags & O_CLOEXEC); + if (fd < 0) + return fd; + + filp = get_empty_filp(); + if (!filp) { + ret = -ENFILE; + goto out_put_fd; + } + + user = get_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 (IS_ERR(ih)) { + ret = PTR_ERR(ih); + goto out_free_dev; + } + dev->ih = ih; + dev->fa = NULL; + + filp->f_op = &inotify_fops; + filp->f_path.mnt = mntget(inotify_mnt); + filp->f_path.dentry = dget(inotify_mnt->mnt_root); + filp->f_mapping = filp->f_path.dentry->d_inode->i_mapping; + filp->f_mode = FMODE_READ; + filp->f_flags = O_RDONLY | (flags & O_NONBLOCK); + 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; +} + +SYSCALL_DEFINE0(inotify_init) +{ + return sys_inotify_init1(0); +} + +SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname, + u32, mask) +{ + struct inode *inode; + struct inotify_device *dev; + struct path path; + 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(pathname, &path, flags); + if (unlikely(ret)) + goto fput_and_out; + + /* inode held in place by reference to path; dev by fget on fd */ + inode = path.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_put(&path); +fput_and_out: + fput_light(filp, fput_needed); + return ret; +} + +SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, 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 int +inotify_get_sb(struct file_system_type *fs_type, int flags, + const char *dev_name, void *data, struct vfsmount *mnt) +{ + return get_sb_pseudo(fs_type, "inotify", NULL, + INOTIFYFS_SUPER_MAGIC, mnt); +} + +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); + event_cachep = kmem_cache_create("inotify_event_cache", + sizeof(struct inotify_kernel_event), + 0, SLAB_PANIC, NULL); + + return 0; +} + +module_init(inotify_user_setup); |