diff options
Diffstat (limited to 'fs/notify')
| -rw-r--r-- | fs/notify/Kconfig | 13 | ||||
| -rw-r--r-- | fs/notify/Makefile | 2 | ||||
| -rw-r--r-- | fs/notify/fsnotify.c | 79 | ||||
| -rw-r--r-- | fs/notify/fsnotify.h | 15 | ||||
| -rw-r--r-- | fs/notify/group.c | 198 | ||||
| -rw-r--r-- | fs/notify/inotify/inotify.c | 20 | ||||
| -rw-r--r-- | fs/notify/notification.c | 121 |
7 files changed, 448 insertions, 0 deletions
diff --git a/fs/notify/Kconfig b/fs/notify/Kconfig index 50914d7303c6..31dac7e3b0f1 100644 --- a/fs/notify/Kconfig +++ b/fs/notify/Kconfig @@ -1,2 +1,15 @@ +config FSNOTIFY + bool "Filesystem notification backend" + default y + ---help--- + fsnotify is a backend for filesystem notification. fsnotify does + not provide any userspace interface but does provide the basis + needed for other notification schemes such as dnotify, inotify, + and fanotify. + + Say Y here to enable fsnotify suport. + + If unsure, say Y. + source "fs/notify/dnotify/Kconfig" source "fs/notify/inotify/Kconfig" diff --git a/fs/notify/Makefile b/fs/notify/Makefile index 5a95b6010ce7..db5467b5b58d 100644 --- a/fs/notify/Makefile +++ b/fs/notify/Makefile @@ -1,2 +1,4 @@ +obj-$(CONFIG_FSNOTIFY) += fsnotify.o notification.o group.o + obj-y += dnotify/ obj-y += inotify/ diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c new file mode 100644 index 000000000000..56bee0f10c38 --- /dev/null +++ b/fs/notify/fsnotify.c @@ -0,0 +1,79 @@ +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program; see the file COPYING. If not, write to + * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/dcache.h> +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/srcu.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +/* + * This is the main call to fsnotify. The VFS calls into hook specific functions + * in linux/fsnotify.h. Those functions then in turn call here. Here will call + * out to all of the registered fsnotify_group. Those groups can then use the + * notification event in whatever means they feel necessary. + */ +void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is) +{ + struct fsnotify_group *group; + struct fsnotify_event *event = NULL; + int idx; + + if (list_empty(&fsnotify_groups)) + return; + + if (!(mask & fsnotify_mask)) + return; + + /* + * SRCU!! the groups list is very very much read only and the path is + * very hot. The VAST majority of events are not going to need to do + * anything other than walk the list so it's crazy to pre-allocate. + */ + idx = srcu_read_lock(&fsnotify_grp_srcu); + list_for_each_entry_rcu(group, &fsnotify_groups, group_list) { + if (mask & group->mask) { + if (!event) { + event = fsnotify_create_event(to_tell, mask, data, data_is); + /* shit, we OOM'd and now we can't tell, maybe + * someday someone else will want to do something + * here */ + if (!event) + break; + } + group->ops->handle_event(group, event); + } + } + srcu_read_unlock(&fsnotify_grp_srcu, idx); + /* + * fsnotify_create_event() took a reference so the event can't be cleaned + * up while we are still trying to add it to lists, drop that one. + */ + if (event) + fsnotify_put_event(event); +} +EXPORT_SYMBOL_GPL(fsnotify); + +static __init int fsnotify_init(void) +{ + return init_srcu_struct(&fsnotify_grp_srcu); +} +subsys_initcall(fsnotify_init); diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h new file mode 100644 index 000000000000..c6a8bd476572 --- /dev/null +++ b/fs/notify/fsnotify.h @@ -0,0 +1,15 @@ +#ifndef __FS_NOTIFY_FSNOTIFY_H_ +#define __FS_NOTIFY_FSNOTIFY_H_ + +#include <linux/list.h> +#include <linux/fsnotify.h> +#include <linux/srcu.h> +#include <linux/types.h> + +/* protects reads of fsnotify_groups */ +extern struct srcu_struct fsnotify_grp_srcu; +/* all groups which receive fsnotify events */ +extern struct list_head fsnotify_groups; +/* all bitwise OR of all event types (FS_*) for all fsnotify_groups */ +extern __u32 fsnotify_mask; +#endif /* __FS_NOTIFY_FSNOTIFY_H_ */ diff --git a/fs/notify/group.c b/fs/notify/group.c new file mode 100644 index 000000000000..c6812953b968 --- /dev/null +++ b/fs/notify/group.c @@ -0,0 +1,198 @@ +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program; see the file COPYING. If not, write to + * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/list.h> +#include <linux/mutex.h> +#include <linux/slab.h> +#include <linux/srcu.h> +#include <linux/rculist.h> +#include <linux/wait.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +#include <asm/atomic.h> + +/* protects writes to fsnotify_groups and fsnotify_mask */ +static DEFINE_MUTEX(fsnotify_grp_mutex); +/* protects reads while running the fsnotify_groups list */ +struct srcu_struct fsnotify_grp_srcu; +/* all groups registered to receive filesystem notifications */ +LIST_HEAD(fsnotify_groups); +/* bitwise OR of all events (FS_*) interesting to some group on this system */ +__u32 fsnotify_mask; + +/* + * When a new group registers or changes it's set of interesting events + * this function updates the fsnotify_mask to contain all interesting events + */ +void fsnotify_recalc_global_mask(void) +{ + struct fsnotify_group *group; + __u32 mask = 0; + int idx; + + idx = srcu_read_lock(&fsnotify_grp_srcu); + list_for_each_entry_rcu(group, &fsnotify_groups, group_list) + mask |= group->mask; + srcu_read_unlock(&fsnotify_grp_srcu, idx); + fsnotify_mask = mask; +} + +/* + * Take a reference to a group so things found under the fsnotify_grp_mutex + * can't get freed under us + */ +static void fsnotify_get_group(struct fsnotify_group *group) +{ + atomic_inc(&group->refcnt); +} + +/* + * Final freeing of a group + */ +static void fsnotify_destroy_group(struct fsnotify_group *group) +{ + if (group->ops->free_group_priv) + group->ops->free_group_priv(group); + + kfree(group); +} + +/* + * Remove this group from the global list of groups that will get events + * this can be done even if there are still references and things still using + * this group. This just stops the group from getting new events. + */ +static void __fsnotify_evict_group(struct fsnotify_group *group) +{ + BUG_ON(!mutex_is_locked(&fsnotify_grp_mutex)); + + if (group->on_group_list) + list_del_rcu(&group->group_list); + group->on_group_list = 0; +} + +/* + * Called when a group is no longer interested in getting events. This can be + * used if a group is misbehaving or if for some reason a group should no longer + * get any filesystem events. + */ +void fsnotify_evict_group(struct fsnotify_group *group) +{ + mutex_lock(&fsnotify_grp_mutex); + __fsnotify_evict_group(group); + mutex_unlock(&fsnotify_grp_mutex); +} + +/* + * Drop a reference to a group. Free it if it's through. + */ +void fsnotify_put_group(struct fsnotify_group *group) +{ + if (!atomic_dec_and_mutex_lock(&group->refcnt, &fsnotify_grp_mutex)) + return; + + /* + * OK, now we know that there's no other users *and* we hold mutex, + * so no new references will appear + */ + __fsnotify_evict_group(group); + + /* + * now it's off the list, so the only thing we might care about is + * srcu access.... + */ + mutex_unlock(&fsnotify_grp_mutex); + synchronize_srcu(&fsnotify_grp_srcu); + + /* and now it is really dead. _Nothing_ could be seeing it */ + fsnotify_recalc_global_mask(); + fsnotify_destroy_group(group); +} + +/* + * Simply run the fsnotify_groups list and find a group which matches + * the given parameters. If a group is found we take a reference to that + * group. + */ +static struct fsnotify_group *fsnotify_find_group(unsigned int group_num, __u32 mask, + const struct fsnotify_ops *ops) +{ + struct fsnotify_group *group_iter; + struct fsnotify_group *group = NULL; + + BUG_ON(!mutex_is_locked(&fsnotify_grp_mutex)); + + list_for_each_entry_rcu(group_iter, &fsnotify_groups, group_list) { + if (group_iter->group_num == group_num) { + if ((group_iter->mask == mask) && + (group_iter->ops == ops)) { + fsnotify_get_group(group_iter); + group = group_iter; + } else + group = ERR_PTR(-EEXIST); + } + } + return group; +} + +/* + * Either finds an existing group which matches the group_num, mask, and ops or + * creates a new group and adds it to the global group list. In either case we + * take a reference for the group returned. + */ +struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num, __u32 mask, + const struct fsnotify_ops *ops) +{ + struct fsnotify_group *group, *tgroup; + + /* very low use, simpler locking if we just always alloc */ + group = kmalloc(sizeof(struct fsnotify_group), GFP_KERNEL); + if (!group) + return ERR_PTR(-ENOMEM); + + atomic_set(&group->refcnt, 1); + + group->on_group_list = 0; + group->group_num = group_num; + group->mask = mask; + + group->ops = ops; + + mutex_lock(&fsnotify_grp_mutex); + tgroup = fsnotify_find_group(group_num, mask, ops); + if (tgroup) { + /* group already exists */ + mutex_unlock(&fsnotify_grp_mutex); + /* destroy the new one we made */ + fsnotify_put_group(group); + return tgroup; + } + + /* group not found, add a new one */ + list_add_rcu(&group->group_list, &fsnotify_groups); + group->on_group_list = 1; + + mutex_unlock(&fsnotify_grp_mutex); + + if (mask) + fsnotify_recalc_global_mask(); + + return group; +} diff --git a/fs/notify/inotify/inotify.c b/fs/notify/inotify/inotify.c index 220c13f0d73d..40b1cf914ccb 100644 --- a/fs/notify/inotify/inotify.c +++ b/fs/notify/inotify/inotify.c @@ -32,6 +32,7 @@ #include <linux/list.h> #include <linux/writeback.h> #include <linux/inotify.h> +#include <linux/fsnotify_backend.h> static atomic_t inotify_cookie; @@ -905,6 +906,25 @@ EXPORT_SYMBOL_GPL(inotify_rm_watch); */ static int __init inotify_setup(void) { + BUILD_BUG_ON(IN_ACCESS != FS_ACCESS); + BUILD_BUG_ON(IN_MODIFY != FS_MODIFY); + BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB); + BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE); + BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); + BUILD_BUG_ON(IN_OPEN != FS_OPEN); + BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM); + BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO); + BUILD_BUG_ON(IN_CREATE != FS_CREATE); + BUILD_BUG_ON(IN_DELETE != FS_DELETE); + BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF); + BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF); + BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW); + + BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT); + BUILD_BUG_ON(IN_ISDIR != FS_IN_ISDIR); + BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED); + BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT); + atomic_set(&inotify_cookie, 0); return 0; diff --git a/fs/notify/notification.c b/fs/notify/notification.c new file mode 100644 index 000000000000..b8e9a87f8f58 --- /dev/null +++ b/fs/notify/notification.c @@ -0,0 +1,121 @@ +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program; see the file COPYING. If not, write to + * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/mount.h> +#include <linux/mutex.h> +#include <linux/namei.h> +#include <linux/path.h> +#include <linux/slab.h> +#include <linux/spinlock.h> + +#include <asm/atomic.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +static struct kmem_cache *fsnotify_event_cachep; + +void fsnotify_get_event(struct fsnotify_event *event) +{ + atomic_inc(&event->refcnt); +} + +void fsnotify_put_event(struct fsnotify_event *event) +{ + if (!event) + return; + + if (atomic_dec_and_test(&event->refcnt)) { + if (event->data_type == FSNOTIFY_EVENT_PATH) + path_put(&event->path); + + kmem_cache_free(fsnotify_event_cachep, event); + } +} + +/* + * Allocate a new event which will be sent to each group's handle_event function + * if the group was interested in this particular event. + */ +struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask, + void *data, int data_type) +{ + struct fsnotify_event *event; + + event = kmem_cache_alloc(fsnotify_event_cachep, GFP_KERNEL); + if (!event) + return NULL; + + atomic_set(&event->refcnt, 1); + + spin_lock_init(&event->lock); + + event->path.dentry = NULL; + event->path.mnt = NULL; + event->inode = NULL; + + event->to_tell = to_tell; + + switch (data_type) { + case FSNOTIFY_EVENT_FILE: { + struct file *file = data; + struct path *path = &file->f_path; + event->path.dentry = path->dentry; + event->path.mnt = path->mnt; + path_get(&event->path); + event->data_type = FSNOTIFY_EVENT_PATH; + break; + } + case FSNOTIFY_EVENT_PATH: { + struct path *path = data; + event->path.dentry = path->dentry; + event->path.mnt = path->mnt; + path_get(&event->path); + event->data_type = FSNOTIFY_EVENT_PATH; + break; + } + case FSNOTIFY_EVENT_INODE: + event->inode = data; + event->data_type = FSNOTIFY_EVENT_INODE; + break; + case FSNOTIFY_EVENT_NONE: + event->inode = NULL; + event->path.dentry = NULL; + event->path.mnt = NULL; + break; + default: + BUG(); + } + + event->mask = mask; + + return event; +} + +__init int fsnotify_notification_init(void) +{ + fsnotify_event_cachep = KMEM_CACHE(fsnotify_event, SLAB_PANIC); + + return 0; +} +subsys_initcall(fsnotify_notification_init); + |