diff options
| -rw-r--r-- | Documentation/filesystems/inotify.txt | 138 | ||||
| -rw-r--r-- | arch/i386/kernel/syscall_table.S | 3 | ||||
| -rw-r--r-- | fs/Kconfig | 13 | ||||
| -rw-r--r-- | fs/Makefile | 1 | ||||
| -rw-r--r-- | fs/attr.c | 33 | ||||
| -rw-r--r-- | fs/compat.c | 12 | ||||
| -rw-r--r-- | fs/file_table.c | 3 | ||||
| -rw-r--r-- | fs/inode.c | 6 | ||||
| -rw-r--r-- | fs/inotify.c | 999 | ||||
| -rw-r--r-- | fs/namei.c | 30 | ||||
| -rw-r--r-- | fs/nfsd/vfs.c | 6 | ||||
| -rw-r--r-- | fs/open.c | 3 | ||||
| -rw-r--r-- | fs/read_write.c | 15 | ||||
| -rw-r--r-- | fs/sysfs/file.c | 7 | ||||
| -rw-r--r-- | fs/xattr.c | 5 | ||||
| -rw-r--r-- | include/asm-i386/unistd.h | 5 | ||||
| -rw-r--r-- | include/linux/fs.h | 6 | ||||
| -rw-r--r-- | include/linux/fsnotify.h | 248 | ||||
| -rw-r--r-- | include/linux/inotify.h | 108 | ||||
| -rw-r--r-- | include/linux/sched.h | 4 | ||||
| -rw-r--r-- | include/linux/sysctl.h | 11 | ||||
| -rw-r--r-- | kernel/sys_ni.c | 3 | ||||
| -rw-r--r-- | kernel/sysctl.c | 43 | ||||
| -rw-r--r-- | kernel/user.c | 4 |
24 files changed, 1639 insertions, 67 deletions
diff --git a/Documentation/filesystems/inotify.txt b/Documentation/filesystems/inotify.txt new file mode 100644 index 00000000000..2c716041f57 --- /dev/null +++ b/Documentation/filesystems/inotify.txt @@ -0,0 +1,138 @@ + inotify + a powerful yet simple file change notification system + + + +Document started 15 Mar 2005 by Robert Love <rml@novell.com> + +(i) User Interface + +Inotify is controlled by a set of three sys calls + +First step in using inotify is to initialise an inotify instance + + int fd = inotify_init (); + +Change events are managed by "watches". A watch is an (object,mask) pair where +the object is a file or directory and the mask is a bit mask of one or more +inotify events that the application wishes to receive. See <linux/inotify.h> +for valid events. A watch is referenced by a watch descriptor, or wd. + +Watches are added via a path to the file. + +Watches on a directory will return events on any files inside of the directory. + +Adding a watch is simple, + + int wd = inotify_add_watch (fd, path, mask); + +You can add a large number of files via something like + + for each file to watch { + int wd = inotify_add_watch (fd, file, mask); + } + +You can update an existing watch in the same manner, by passing in a new mask. + +An existing watch is removed via the INOTIFY_IGNORE ioctl, for example + + inotify_rm_watch (fd, wd); + +Events are provided in the form of an inotify_event structure that is read(2) +from a inotify instance fd. The filename is of dynamic length and follows the +struct. It is of size len. The filename is padded with null bytes to ensure +proper alignment. This padding is reflected in len. + +You can slurp multiple events by passing a large buffer, for example + + size_t len = read (fd, buf, BUF_LEN); + +Will return as many events as are available and fit in BUF_LEN. + +each inotify instance fd is also select()- and poll()-able. + +You can find the size of the current event queue via the FIONREAD ioctl. + +All watches are destroyed and cleaned up on close. + + +(ii) Internal Kernel Implementation + +Each open inotify instance is associated with an inotify_device structure. + +Each watch is associated with an inotify_watch structure. Watches are chained +off of each associated device and each associated inode. + +See fs/inotify.c for the locking and lifetime rules. + + +(iii) Rationale + +Q: What is the design decision behind not tying the watch to the open fd of + the watched object? + +A: Watches are associated with an open inotify device, not an open file. + This solves the primary problem with dnotify: keeping the file open pins + the file and thus, worse, pins the mount. Dnotify is therefore infeasible + for use on a desktop system with removable media as the media cannot be + unmounted. + +Q: What is the design decision behind using an-fd-per-device as opposed to + an fd-per-watch? + +A: An fd-per-watch quickly consumes more file descriptors than are allowed, + more fd's than are feasible to manage, and more fd's than are optimally + select()-able. Yes, root can bump the per-process fd limit and yes, users + can use epoll, but requiring both is a silly and extraneous requirement. + A watch consumes less memory than an open file, separating the number + spaces is thus sensible. The current design is what user-space developers + want: Users initialize inotify, once, and add n watches, requiring but one fd + and no twiddling with fd limits. Initializing an inotify instance two + thousand times is silly. If we can implement user-space's preferences + cleanly--and we can, the idr layer makes stuff like this trivial--then we + should. + + There are other good arguments. With a single fd, there is a single + item to block on, which is mapped to a single queue of events. The single + fd returns all watch events and also any potential out-of-band data. If + every fd was a separate watch, + + - There would be no way to get event ordering. Events on file foo and + file bar would pop poll() on both fd's, but there would be no way to tell + which happened first. A single queue trivially gives you ordering. Such + ordering is crucial to existing applications such as Beagle. Imagine + "mv a b ; mv b a" events without ordering. + + - We'd have to maintain n fd's and n internal queues with state, + versus just one. It is a lot messier in the kernel. A single, linear + queue is the data structure that makes sense. + + - User-space developers prefer the current API. The Beagle guys, for + example, love it. Trust me, I asked. It is not a surprise: Who'd want + to manage and block on 1000 fd's via select? + + - You'd have to manage the fd's, as an example: Call close() when you + received a delete event. + + - No way to get out of band data. + + - 1024 is still too low. ;-) + + When you talk about designing a file change notification system that + scales to 1000s of directories, juggling 1000s of fd's just does not seem + the right interface. It is too heavy. + +Q: Why the system call approach? + +A: The poor user-space interface is the second biggest problem with dnotify. + Signals are a terrible, terrible interface for file notification. Or for + anything, for that matter. The ideal solution, from all perspectives, is a + file descriptor-based one that allows basic file I/O and poll/select. + Obtaining the fd and managing the watches could have been done either via a + device file or a family of new system calls. We decided to implement a + family of system calls because that is the preffered approach for new kernel + features and it means our user interface requirements. + + Additionally, it _is_ possible to more than one instance and + juggle more than one queue and thus more than one associated fd. + diff --git a/arch/i386/kernel/syscall_table.S b/arch/i386/kernel/syscall_table.S index 3db9a04aec6..468500a7e89 100644 --- a/arch/i386/kernel/syscall_table.S +++ b/arch/i386/kernel/syscall_table.S @@ -291,3 +291,6 @@ ENTRY(sys_call_table) .long sys_keyctl .long sys_ioprio_set .long sys_ioprio_get /* 290 */ + .long sys_inotify_init + .long sys_inotify_add_watch + .long sys_inotify_rm_watch diff --git a/fs/Kconfig b/fs/Kconfig index f93fd41b025..5d0c4be43db 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -359,6 +359,19 @@ config ROMFS_FS If you don't know whether you need it, then you don't need it: answer N. +config INOTIFY + bool "Inotify file change notification support" + default y + ---help--- + Say Y here to enable inotify support and the /dev/inotify character + device. Inotify is a file change notification system and a + replacement for dnotify. Inotify fixes numerous shortcomings in + dnotify and introduces several new features. It allows monitoring + of both files and directories via a single open fd. Multiple file + events are supported. + + If unsure, say Y. + config QUOTA bool "Quota support" help diff --git a/fs/Makefile b/fs/Makefile index 20edcf28bfd..cf95eb894fd 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -12,6 +12,7 @@ obj-y := open.o read_write.o file_table.o buffer.o bio.o super.o \ seq_file.o xattr.o libfs.o fs-writeback.o mpage.o direct-io.o \ ioprio.o +obj-$(CONFIG_INOTIFY) += inotify.o obj-$(CONFIG_EPOLL) += eventpoll.o obj-$(CONFIG_COMPAT) += compat.o diff --git a/fs/attr.c b/fs/attr.c index c3c76fe7834..b1796fb9e52 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -10,7 +10,7 @@ #include <linux/mm.h> #include <linux/string.h> #include <linux/smp_lock.h> -#include <linux/dnotify.h> +#include <linux/fsnotify.h> #include <linux/fcntl.h> #include <linux/quotaops.h> #include <linux/security.h> @@ -107,31 +107,8 @@ int inode_setattr(struct inode * inode, struct iattr * attr) out: return error; } - EXPORT_SYMBOL(inode_setattr); -int setattr_mask(unsigned int ia_valid) -{ - unsigned long dn_mask = 0; - - if (ia_valid & ATTR_UID) - dn_mask |= DN_ATTRIB; - if (ia_valid & ATTR_GID) - dn_mask |= DN_ATTRIB; - if (ia_valid & ATTR_SIZE) - dn_mask |= DN_MODIFY; - /* both times implies a utime(s) call */ - if ((ia_valid & (ATTR_ATIME|ATTR_MTIME)) == (ATTR_ATIME|ATTR_MTIME)) - dn_mask |= DN_ATTRIB; - else if (ia_valid & ATTR_ATIME) - dn_mask |= DN_ACCESS; - else if (ia_valid & ATTR_MTIME) - dn_mask |= DN_MODIFY; - if (ia_valid & ATTR_MODE) - dn_mask |= DN_ATTRIB; - return dn_mask; -} - int notify_change(struct dentry * dentry, struct iattr * attr) { struct inode *inode = dentry->d_inode; @@ -197,11 +174,9 @@ int notify_change(struct dentry * dentry, struct iattr * attr) if (ia_valid & ATTR_SIZE) up_write(&dentry->d_inode->i_alloc_sem); - if (!error) { - unsigned long dn_mask = setattr_mask(ia_valid); - if (dn_mask) - dnotify_parent(dentry, dn_mask); - } + if (!error) + fsnotify_change(dentry, ia_valid); + return error; } diff --git a/fs/compat.c b/fs/compat.c index 728cd836538..6b06b6bae35 100644 --- a/fs/compat.c +++ b/fs/compat.c @@ -37,7 +37,7 @@ #include <linux/ctype.h> #include <linux/module.h> #include <linux/dirent.h> -#include <linux/dnotify.h> +#include <linux/fsnotify.h> #include <linux/highuid.h> #include <linux/sunrpc/svc.h> #include <linux/nfsd/nfsd.h> @@ -1307,9 +1307,13 @@ static ssize_t compat_do_readv_writev(int type, struct file *file, out: if (iov != iovstack) kfree(iov); - if ((ret + (type == READ)) > 0) - dnotify_parent(file->f_dentry, - (type == READ) ? DN_ACCESS : DN_MODIFY); + if ((ret + (type == READ)) > 0) { + struct dentry *dentry = file->f_dentry; + if (type == READ) + fsnotify_access(dentry); + else + fsnotify_modify(dentry); + } return ret; } diff --git a/fs/file_table.c b/fs/file_table.c index fa7849fae13..1d3de78e6bc 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -16,6 +16,7 @@ #include <linux/eventpoll.h> #include <linux/mount.h> #include <linux/cdev.h> +#include <linux/fsnotify.h> /* sysctl tunables... */ struct files_stat_struct files_stat = { @@ -126,6 +127,8 @@ void fastcall __fput(struct file *file) struct inode *inode = dentry->d_inode; might_sleep(); + + fsnotify_close(file); /* * The function eventpoll_release() should be the first called * in the file cleanup chain. diff --git a/fs/inode.c b/fs/inode.c index 5bc97507eea..96364fae084 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -21,6 +21,7 @@ #include <linux/pagemap.h> #include <linux/cdev.h> #include <linux/bootmem.h> +#include <linux/inotify.h> /* * This is needed for the following functions: @@ -202,6 +203,10 @@ void inode_init_once(struct inode *inode) INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear); spin_lock_init(&inode->i_lock); i_size_ordered_init(inode); +#ifdef CONFIG_INOTIFY + INIT_LIST_HEAD(&inode->inotify_watches); + sema_init(&inode->inotify_sem, 1); +#endif } EXPORT_SYMBOL(inode_init_once); @@ -351,6 +356,7 @@ int invalidate_inodes(struct super_block * sb) down(&iprune_sem); spin_lock(&inode_lock); + inotify_unmount_inodes(&sb->s_inodes); busy = invalidate_list(&sb->s_inodes, &throw_away); spin_unlock(&inode_lock); diff --git a/fs/inotify.c b/fs/inotify.c new file mode 100644 index 00000000000..e423bfe0c86 --- /dev/null +++ b/fs/inotify.c @@ -0,0 +1,999 @@ +/* + * fs/inotify.c - inode-based file event notifications + * + * Authors: + * John McCutchan <ttb@tentacle.dhs.org> + * Robert Love <rml@novell.com> + * + * Copyright (C) 2005 John McCutchan + * + * 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/sched.h> +#include <linux/spinlock.h> +#include <linux/idr.h> +#include <linux/slab.h> +#include <linux/fs.h> +#include <linux/file.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include <linux/poll.h> +#include <linux/device.h> +#include <linux/miscdevice.h> +#include <linux/init.h> +#include <linux/list.h> +#include <linux/writeback.h> +#include <linux/inotify.h> + +#include <asm/ioctls.h> + +static atomic_t inotify_cookie; + +static kmem_cache_t *watch_cachep; +static kmem_cache_t *event_cachep; + +static struct vfsmount *inotify_mnt; + +/* These are configurable via /proc/sys/inotify */ +int inotify_max_user_devices; +int inotify_max_user_watches; +int inotify_max_queued_events; + +/* + * Lock ordering: + * + * dentry->d_lock (used to keep d_move() away from dentry->d_parent) + * iprune_sem (synchronize shrink_icache_memory()) + * inode_lock (protects the super_block->s_inodes list) + * inode->inotify_sem (protects inode->inotify_watches and watches->i_list) + * inotify_dev->sem (protects inotify_device and watches->d_list) + */ + +/* + * Lifetimes of the three main data structures--inotify_device, inode, and + * inotify_watch--are managed by reference count. + * + * inotify_device: Lifetime is from open until release. Additional references + * can bump the count via get_inotify_dev() and drop the count via + * put_inotify_dev(). + * + * inotify_watch: Lifetime is from create_watch() to destory_watch(). + * Additional references can bump the count via get_inotify_watch() and drop + * the count via put_inotify_watch(). + * + * inode: Pinned so long as the inode is associated with a watch, from + * create_watch() to put_inotify_watch(). + */ + +/* + * struct inotify_device - represents an open instance of an inotify device + * + * This structure is protected by the semaphore 'sem'. + */ +struct inotify_device { + wait_queue_head_t wq; /* wait queue for i/o */ + struct idr idr; /* idr mapping wd -> watch */ + struct semaphore sem; /* protects this bad boy */ + struct list_head events; /* list of queued events */ + struct list_head watches; /* list of watches */ + atomic_t count; /* reference count */ + struct user_struct *user; /* user who opened this dev */ + unsigned int queue_size; /* size of the queue (bytes) */ + unsigned int event_count; /* number of pending events */ + unsigned int max_events; /* maximum number of events */ +}; + +/* + * 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->sem of the device in which we are queued. + */ +struct inotify_kernel_event { + struct inotify_event event; /* the user-space event */ + struct list_head list; /* entry in inotify_device's list */ + char *name; /* filename, if any */ +}; + +/* + * struct inotify_watch - represents a watch request on a specific inode + * + * d_list is protected by dev->sem of the associated watch->dev. + * i_list and mask are protected by inode->inotify_sem of the associated inode. + * dev, inode, and wd are never written to once the watch is created. + */ +struct inotify_watch { + struct list_head d_list; /* entry in inotify_device's list */ + struct list_head i_list; /* entry in inode's list */ + atomic_t count; /* reference count */ + struct inotify_device *dev; /* associated device */ + struct inode *inode; /* associated inode */ + s32 wd; /* watch descriptor */ + u32 mask; /* event mask for this watch */ +}; + +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); + } +} + +static inline void get_inotify_watch(struct inotify_watch *watch) +{ + atomic_inc(&watch->count); +} + +/* + * put_inotify_watch - decrements the ref count on a given watch. cleans up + * the watch and its references if the count reaches zero. + */ +static inline void put_inotify_watch(struct inotify_watch *watch) +{ + if (atomic_dec_and_test(&watch->count)) { + put_inotify_dev(watch->dev); + iput(watch->inode); + kmem_cache_free(watch_cachep, watch); + } +} + +/* + * kernel_event - create a new kernel event with the given parameters + * + * This function can sleep. + */ +static struct inotify_kernel_event * kernel_event(s32 wd, u32 mask, u32 cookie, + const char *name) +{ + struct inotify_kernel_event *kevent; + + kevent = kmem_cache_alloc(event_cachep, GFP_KERNEL); + if (unlikely(!kevent)) + return NULL; + + /* we hand this out to user-space, so zero it just in case */ + memset(&kevent->event, 0, sizeof(struct inotify_event)); + + kevent->event.wd = wd; + kevent->event.mask = mask; + kevent->event.cookie = cookie; + + INIT_LIST_HEAD(&kevent->list); + + if (name) { + size_t len, rem, event_size = sizeof(struct inotify_event); + + /* + * We need to pad the filename so as to properly align an + * array of inotify_event structures. Because the structure is + * small and the common case is a small filename, we just round + * up to the next multiple of the structure's sizeof. This is + * simple and safe for all architectures. + */ + len = strlen(name) + 1; + rem = event_size - len; + if (len > event_size) { + rem = event_size - (len % event_size); + if (len % event_size == 0) + rem = 0; + } + + kevent->name = kmalloc(len + rem, GFP_KERNEL); + if (unlikely(!kevent->name)) { + kmem_cache_free(event_cachep, kevent); + return NULL; + } + memcpy(kevent->name, name, len); + if (rem) + memset(kevent->name + len, 0, rem); + kevent->event.len = len + rem; + } else { + kevent->event.len = 0; + kevent->name = NULL; + } + + return kevent; +} + +/* + * inotify_dev_get_event - return the next event in the given dev's queue + * + * Caller must hold dev->sem. + */ +static inline struct inotify_kernel_event * +inotify_dev_get_event(struct inotify_device *dev) +{ + return list_entry(dev->events.next, struct inotify_kernel_event, list); +} + +/* + * inotify_dev_queue_event - add a new event to the given device + * + * Caller must hold dev->sem. Can sleep (calls kernel_event()). + */ +static void inotify_dev_queue_event(struct inotify_device *dev, + struct inotify_watch *watch, u32 mask, + u32 cookie, const char *name) +{ + struct inotify_kernel_event *kevent, *last; + + /* coalescing: drop this event if it is a dupe of the previous */ + last = inotify_dev_get_event(dev); + if (last && last->event.mask == mask && last->event.wd == watch->wd && + last->event.cookie == cookie) { + const char *lastname = last->name; + + if (!name && !lastname) + return; + if (name && lastname && !strcmp(lastname, name)) + return; + } + + /* the queue overflowed and we already sent the Q_OVERFLOW event */ + if (unlikely(dev->event_count > dev->max_events)) + return; + + /* if the queue overflows, we need to notify user space */ + if (unlikely(dev->event_count == dev->max_events)) + kevent = kernel_event(-1, IN_Q_OVERFLOW, cookie, NULL); + else + kevent = kernel_event(watch->wd, mask, cookie, name); + + if (unlikely(!kevent)) + return; + + /* queue the event and wake up anyone waiting */ + dev->event_count++; + dev->queue_size += sizeof(struct inotify_event) + kevent->event.len; + list_add_tail(&kevent->list, &dev->events); + wake_up_interruptible(&dev->wq); +} + +/* + * remove_kevent - cleans up and ultimately frees the given kevent + * + * Caller must hold dev->sem. + */ +static void remove_kevent(struct inotify_device *dev, + struct inotify_kernel_event *kevent) +{ + list_del(&kevent->list); + + dev->event_count--; + dev->queue_size -= sizeof(struct inotify_event) + kevent->event.len; + + kfree(kevent->name); + kmem_cache_free(event_cachep, kevent); +} + +/* + * inotify_dev_event_dequeue - destroy an event on the given device + * + * Caller must hold dev->sem. + */ +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); + } +} + +/* + * inotify_dev_get_wd - returns the next WD for use by the given dev + * + * Callers must hold dev->sem. This function can sleep. + */ +static int inotify_dev_get_wd(struct inotify_device *dev, + struct inotify_watch *watch) +{ + int ret; + + do { + if (unlikely(!idr_pre_get(&dev->idr, GFP_KERNEL))) + return -ENOSPC; + ret = idr_get_new(&dev->idr, watch, &watch->wd); + } while (ret == -EAGAIN); + + return ret; +} + +/* + * find_inode - resolve a user-given path to a specific inode and return a nd + */ +static int find_inode(const char __user *dirname, struct nameidata *nd) +{ + int error; + + error = __user_walk(dirname, LOOKUP_FOLLOW, nd); + if (error) + return error; + /* you can only watch an inode if you have read permissions on it */ + error = permission(nd->dentry->d_inode, MAY_READ, NULL); + if (error) + path_release (nd); + return error; +} + +/* + * create_watch - creates a watch on the given device. + * + * Callers must hold dev->sem. Calls inotify_dev_get_wd() so may sleep. + * Both 'dev' and 'inode' (by way of nameidata) need to be pinned. + */ +static struct inotify_watch *create_watch(struct inotify_device *dev, + u32 mask, struct inode *inode) +{ + struct inotify_watch *watch; + int ret; + + if (atomic_read(&dev->user->inotify_watches) >= inotify_max_user_watches) + return ERR_PTR(-ENOSPC); + + watch = kmem_cache_alloc(watch_cachep, GFP_KERNEL); + if (unlikely(!watch)) + return ERR_PTR(-ENOMEM); + + ret = inotify_dev_get_wd(dev, watch); + if (unlikely(ret)) { + kmem_cache_free(watch_cachep, watch); + return ERR_PTR(ret); + } + + watch->mask = mask; + atomic_set(&watch->count, 0); + INIT_LIST_HEAD(&watch->d_list); + INIT_LIST_HEAD(&watch->i_list); + + /* save a reference to device and bump the count to make it official */ + get_inotify_dev(dev); + watch->dev = dev; + + /* + * Save a reference to the inode and bump the ref count to make it + * official. We hold a reference to nameidata, which makes this safe. + */ + watch->inode = igrab(inode); + + /* bump our own count, corresponding to our entry in dev->watches */ + get_inotify_watch(watch); + + atomic_inc(&dev->user->inotify_watches); + + return watch; +} + +/* + * inotify_find_dev - find the watch associated with the given inode and dev + * + * Callers must hold inode->inotify_sem. + */ +static struct inotify_watch *inode_find_dev(struct inode *inode, + struct inotify_device *dev) +{ + struct inotify_watch *watch; + + list_for_each_entry(watch, &inode->inotify_watches, i_list) { + if (watch->dev == dev) + return watch; + } + + return NULL; +} + +/* + * 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); + + 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_sem and dev->sem. 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); +} + +/* + * 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); +} + +/* Kernel API */ + +/** + * 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; + + down(&inode->inotify_sem); + 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); + down(&dev->sem); + inotify_dev_queue_event(dev, watch, mask, cookie, name); + if (watch_mask & IN_ONESHOT) + remove_watch_no_event(watch, dev); + up(&dev->sem); + put_inotify_watch(watch); + } + } + up(&inode->inotify_sem); +} +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; + + 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_sem 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_sem 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 */ + down(&inode->inotify_sem); + watches = &inode->inotify_watches; + list_for_each_entry_safe(watch, next_w, watches, i_list) { + struct inotify_device *dev = watch->dev; + down(&dev->sem); + inotify_dev_queue_event(dev, watch, IN_UNMOUNT,0,NULL); + remove_watch(watch, dev); + up(&dev->sem); + } + up(&inode->inotify_sem); + 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 |