diff options
Diffstat (limited to 'fs/notify')
| -rw-r--r-- | fs/notify/Kconfig | 5 | ||||
| -rw-r--r-- | fs/notify/Makefile | 4 | ||||
| -rw-r--r-- | fs/notify/dnotify/Kconfig | 11 | ||||
| -rw-r--r-- | fs/notify/dnotify/Makefile | 1 | ||||
| -rw-r--r-- | fs/notify/dnotify/dnotify.c | 442 | ||||
| -rw-r--r-- | fs/notify/fsnotify.c | 188 | ||||
| -rw-r--r-- | fs/notify/fsnotify.h | 34 | ||||
| -rw-r--r-- | fs/notify/group.c | 254 | ||||
| -rw-r--r-- | fs/notify/inode_mark.c | 426 | ||||
| -rw-r--r-- | fs/notify/inotify/Kconfig | 31 | ||||
| -rw-r--r-- | fs/notify/inotify/Makefile | 2 | ||||
| -rw-r--r-- | fs/notify/inotify/inotify.c | 933 | ||||
| -rw-r--r-- | fs/notify/inotify/inotify.h | 22 | ||||
| -rw-r--r-- | fs/notify/inotify/inotify_fsnotify.c | 170 | ||||
| -rw-r--r-- | fs/notify/inotify/inotify_user.c | 829 | ||||
| -rw-r--r-- | fs/notify/notification.c | 421 |
16 files changed, 3773 insertions, 0 deletions
diff --git a/fs/notify/Kconfig b/fs/notify/Kconfig new file mode 100644 index 00000000000..dffbb0911d0 --- /dev/null +++ b/fs/notify/Kconfig @@ -0,0 +1,5 @@ +config FSNOTIFY + def_bool n + +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..0922cc826c4 --- /dev/null +++ b/fs/notify/Makefile @@ -0,0 +1,4 @@ +obj-$(CONFIG_FSNOTIFY) += fsnotify.o notification.o group.o inode_mark.o + +obj-y += dnotify/ +obj-y += inotify/ diff --git a/fs/notify/dnotify/Kconfig b/fs/notify/dnotify/Kconfig new file mode 100644 index 00000000000..f9c1ca139d8 --- /dev/null +++ b/fs/notify/dnotify/Kconfig @@ -0,0 +1,11 @@ +config DNOTIFY + bool "Dnotify support" + select FSNOTIFY + default y + help + Dnotify is a directory-based per-fd file change notification system + that uses signals to communicate events to user-space. There exist + superior alternatives, but some applications may still rely on + dnotify. + + If unsure, say Y. diff --git a/fs/notify/dnotify/Makefile b/fs/notify/dnotify/Makefile new file mode 100644 index 00000000000..f145251dcad --- /dev/null +++ b/fs/notify/dnotify/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_DNOTIFY) += dnotify.o diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c new file mode 100644 index 00000000000..7e54e52964d --- /dev/null +++ b/fs/notify/dnotify/dnotify.c @@ -0,0 +1,442 @@ +/* + * Directory notifications for Linux. + * + * Copyright (C) 2000,2001,2002 Stephen Rothwell + * + * Copyright (C) 2009 Eric Paris <Red Hat Inc> + * dnotify was largly rewritten to use the new fsnotify infrastructure + * + * 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> +#include <linux/fsnotify_backend.h> + +int dir_notify_enable __read_mostly = 1; + +static struct kmem_cache *dnotify_struct_cache __read_mostly; +static struct kmem_cache *dnotify_mark_entry_cache __read_mostly; +static struct fsnotify_group *dnotify_group __read_mostly; +static DEFINE_MUTEX(dnotify_mark_mutex); + +/* + * dnotify will attach one of these to each inode (i_fsnotify_mark_entries) which + * is being watched by dnotify. If multiple userspace applications are watching + * the same directory with dnotify their information is chained in dn + */ +struct dnotify_mark_entry { + struct fsnotify_mark_entry fsn_entry; + struct dnotify_struct *dn; +}; + +/* + * When a process starts or stops watching an inode the set of events which + * dnotify cares about for that inode may change. This function runs the + * list of everything receiving dnotify events about this directory and calculates + * the set of all those events. After it updates what dnotify is interested in + * it calls the fsnotify function so it can update the set of all events relevant + * to this inode. + */ +static void dnotify_recalc_inode_mask(struct fsnotify_mark_entry *entry) +{ + __u32 new_mask, old_mask; + struct dnotify_struct *dn; + struct dnotify_mark_entry *dnentry = container_of(entry, + struct dnotify_mark_entry, + fsn_entry); + + assert_spin_locked(&entry->lock); + + old_mask = entry->mask; + new_mask = 0; + for (dn = dnentry->dn; dn != NULL; dn = dn->dn_next) + new_mask |= (dn->dn_mask & ~FS_DN_MULTISHOT); + entry->mask = new_mask; + + if (old_mask == new_mask) + return; + + if (entry->inode) + fsnotify_recalc_inode_mask(entry->inode); +} + +/* + * Mains fsnotify call where events are delivered to dnotify. + * Find the dnotify mark on the relevant inode, run the list of dnotify structs + * on that mark and determine which of them has expressed interest in receiving + * events of this type. When found send the correct process and signal and + * destroy the dnotify struct if it was not registered to receive multiple + * events. + */ +static int dnotify_handle_event(struct fsnotify_group *group, + struct fsnotify_event *event) +{ + struct fsnotify_mark_entry *entry = NULL; + struct dnotify_mark_entry *dnentry; + struct inode *to_tell; + struct dnotify_struct *dn; + struct dnotify_struct **prev; + struct fown_struct *fown; + __u32 test_mask = event->mask & ~FS_EVENT_ON_CHILD; + + to_tell = event->to_tell; + + spin_lock(&to_tell->i_lock); + entry = fsnotify_find_mark_entry(group, to_tell); + spin_unlock(&to_tell->i_lock); + + /* unlikely since we alreay passed dnotify_should_send_event() */ + if (unlikely(!entry)) + return 0; + dnentry = container_of(entry, struct dnotify_mark_entry, fsn_entry); + + spin_lock(&entry->lock); + prev = &dnentry->dn; + while ((dn = *prev) != NULL) { + if ((dn->dn_mask & test_mask) == 0) { + prev = &dn->dn_next; + continue; + } + fown = &dn->dn_filp->f_owner; + send_sigio(fown, dn->dn_fd, POLL_MSG); + if (dn->dn_mask & FS_DN_MULTISHOT) + prev = &dn->dn_next; + else { + *prev = dn->dn_next; + kmem_cache_free(dnotify_struct_cache, dn); + dnotify_recalc_inode_mask(entry); + } + } + + spin_unlock(&entry->lock); + fsnotify_put_mark(entry); + + return 0; +} + +/* + * Given an inode and mask determine if dnotify would be interested in sending + * userspace notification for that pair. + */ +static bool dnotify_should_send_event(struct fsnotify_group *group, + struct inode *inode, __u32 mask) +{ + struct fsnotify_mark_entry *entry; + bool send; + + /* !dir_notify_enable should never get here, don't waste time checking + if (!dir_notify_enable) + return 0; */ + + /* not a dir, dnotify doesn't care */ + if (!S_ISDIR(inode->i_mode)) + return false; + + spin_lock(&inode->i_lock); + entry = fsnotify_find_mark_entry(group, inode); + spin_unlock(&inode->i_lock); + + /* no mark means no dnotify watch */ + if (!entry) + return false; + + mask = (mask & ~FS_EVENT_ON_CHILD); + send = (mask & entry->mask); + + fsnotify_put_mark(entry); /* matches fsnotify_find_mark_entry */ + + return send; +} + +static void dnotify_free_mark(struct fsnotify_mark_entry *entry) +{ + struct dnotify_mark_entry *dnentry = container_of(entry, + struct dnotify_mark_entry, + fsn_entry); + + BUG_ON(dnentry->dn); + + kmem_cache_free(dnotify_mark_entry_cache, dnentry); +} + +static struct fsnotify_ops dnotify_fsnotify_ops = { + .handle_event = dnotify_handle_event, + .should_send_event = dnotify_should_send_event, + .free_group_priv = NULL, + .freeing_mark = NULL, + .free_event_priv = NULL, +}; + +/* + * Called every time a file is closed. Looks first for a dnotify mark on the + * inode. If one is found run all of the ->dn entries attached to that + * mark for one relevant to this process closing the file and remove that + * dnotify_struct. If that was the last dnotify_struct also remove the + * fsnotify_mark_entry. + */ +void dnotify_flush(struct file *filp, fl_owner_t id) +{ + struct fsnotify_mark_entry *entry; + struct dnotify_mark_entry *dnentry; + 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); + entry = fsnotify_find_mark_entry(dnotify_group, inode); + spin_unlock(&inode->i_lock); + if (!entry) + return; + dnentry = container_of(entry, struct dnotify_mark_entry, fsn_entry); + + mutex_lock(&dnotify_mark_mutex); + + spin_lock(&entry->lock); + prev = &dnentry->dn; + while ((dn = *prev) != NULL) { + if ((dn->dn_owner == id) && (dn->dn_filp == filp)) { + *prev = dn->dn_next; + kmem_cache_free(dnotify_struct_cache, dn); + dnotify_recalc_inode_mask(entry); + break; + } + prev = &dn->dn_next; + } + + spin_unlock(&entry->lock); + + /* nothing else could have found us thanks to the dnotify_mark_mutex */ + if (dnentry->dn == NULL) + fsnotify_destroy_mark_by_entry(entry); + + fsnotify_recalc_group_mask(dnotify_group); + + mutex_unlock(&dnotify_mark_mutex); + + fsnotify_put_mark(entry); +} + +/* this conversion is done only at watch creation */ +static __u32 convert_arg(unsigned long arg) +{ + __u32 new_mask = FS_EVENT_ON_CHILD; + + if (arg & DN_MULTISHOT) + new_mask |= FS_DN_MULTISHOT; + if (arg & DN_DELETE) + new_mask |= (FS_DELETE | FS_MOVED_FROM); + if (arg & DN_MODIFY) + new_mask |= FS_MODIFY; + if (arg & DN_ACCESS) + new_mask |= FS_ACCESS; + if (arg & DN_ATTRIB) + new_mask |= FS_ATTRIB; + if (arg & DN_RENAME) + new_mask |= FS_DN_RENAME; + if (arg & DN_CREATE) + new_mask |= (FS_CREATE | FS_MOVED_TO); + + return new_mask; +} + +/* + * If multiple processes watch the same inode with dnotify there is only one + * dnotify mark in inode->i_fsnotify_mark_entries but we chain a dnotify_struct + * onto that mark. This function either attaches the new dnotify_struct onto + * that list, or it |= the mask onto an existing dnofiy_struct. + */ +static int attach_dn(struct dnotify_struct *dn, struct dnotify_mark_entry *dnentry, + fl_owner_t id, int fd, struct file *filp, __u32 mask) +{ + struct dnotify_struct *odn; + + odn = dnentry->dn; + while (odn != NULL) { + /* adding more events to existing dnofiy_struct? */ + if ((odn->dn_owner == id) && (odn->dn_filp == filp)) { + odn->dn_fd = fd; + odn->dn_mask |= mask; + return -EEXIST; + } + odn = odn->dn_next; + } + + dn->dn_mask = mask; + dn->dn_fd = fd; + dn->dn_filp = filp; + dn->dn_owner = id; + dn->dn_next = dnentry->dn; + dnentry->dn = dn; + + return 0; +} + +/* + * When a process calls fcntl to attach a dnotify watch to a directory it ends + * up here. Allocate both a mark for fsnotify to add and a dnotify_struct to be + * attached to the fsnotify_mark. + */ +int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) +{ + struct dnotify_mark_entry *new_dnentry, *dnentry; + struct fsnotify_mark_entry *new_entry, *entry; + struct dnotify_struct *dn; + struct inode *inode; + fl_owner_t id = current->files; + struct file *f; + int destroy = 0, error = 0; + __u32 mask; + + /* we use these to tell if we need to kfree */ + new_entry = NULL; + dn = NULL; + + if (!dir_notify_enable) { + error = -EINVAL; + goto out_err; + } + + /* a 0 mask means we are explicitly removing the watch */ + if ((arg & ~DN_MULTISHOT) == 0) { + dnotify_flush(filp, id); + error = 0; + goto out_err; + } + + /* dnotify only works on directories */ + inode = filp->f_path.dentry->d_inode; + if (!S_ISDIR(inode->i_mode)) { + error = -ENOTDIR; + goto out_err; + } + + /* expect most fcntl to add new rather than augment old */ + dn = kmem_cache_alloc(dnotify_struct_cache, GFP_KERNEL); + if (!dn) { + error = -ENOMEM; + goto out_err; + } + + /* new fsnotify mark, we expect most fcntl calls to add a new mark */ + new_dnentry = kmem_cache_alloc(dnotify_mark_entry_cache, GFP_KERNEL); + if (!new_dnentry) { + error = -ENOMEM; + goto out_err; + } + + /* convert the userspace DN_* "arg" to the internal FS_* defines in fsnotify */ + mask = convert_arg(arg); + + /* set up the new_entry and new_dnentry */ + new_entry = &new_dnentry->fsn_entry; + fsnotify_init_mark(new_entry, dnotify_free_mark); + new_entry->mask = mask; + new_dnentry->dn = NULL; + + /* this is needed to prevent the fcntl/close race described below */ + mutex_lock(&dnotify_mark_mutex); + + /* add the new_entry or find an old one. */ + spin_lock(&inode->i_lock); + entry = fsnotify_find_mark_entry(dnotify_group, inode); + spin_unlock(&inode->i_lock); + if (entry) { + dnentry = container_of(entry, struct dnotify_mark_entry, fsn_entry); + spin_lock(&entry->lock); + } else { + fsnotify_add_mark(new_entry, dnotify_group, inode); + spin_lock(&new_entry->lock); + entry = new_entry; + dnentry = new_dnentry; + /* we used new_entry, so don't free it */ + new_entry = NULL; + } + + rcu_read_lock(); + f = fcheck(fd); + rcu_read_unlock(); + + /* if (f != filp) means that we lost a race and another task/thread + * actually closed the fd we are still playing with before we grabbed + * the dnotify_mark_mutex and entry->lock. Since closing the fd is the + * only time we clean up the mark entries we need to get our mark off + * the list. */ + if (f != filp) { + /* if we added ourselves, shoot ourselves, it's possible that + * the flush actually did shoot this entry. That's fine too + * since multiple calls to destroy_mark is perfectly safe, if + * we found a dnentry already attached to the inode, just sod + * off silently as the flush at close time dealt with it. + */ + if (dnentry == new_dnentry) + destroy = 1; + goto out; + } + + error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); + if (error) { + /* if we added, we must shoot */ + if (dnentry == new_dnentry) + destroy = 1; + goto out; + } + + error = attach_dn(dn, dnentry, id, fd, filp, mask); + /* !error means that we attached the dn to the dnentry, so don't free it */ + if (!error) + dn = NULL; + /* -EEXIST means that we didn't add this new dn and used an old one. + * that isn't an error (and the unused dn should be freed) */ + else if (error == -EEXIST) + error = 0; + + dnotify_recalc_inode_mask(entry); +out: + spin_unlock(&entry->lock); + + if (destroy) + fsnotify_destroy_mark_by_entry(entry); + + fsnotify_recalc_group_mask(dnotify_group); + + mutex_unlock(&dnotify_mark_mutex); + fsnotify_put_mark(entry); +out_err: + if (new_entry) + fsnotify_put_mark(new_entry); + if (dn) + kmem_cache_free(dnotify_struct_cache, dn); + return error; +} + +static int __init dnotify_init(void) +{ + dnotify_struct_cache = KMEM_CACHE(dnotify_struct, SLAB_PANIC); + dnotify_mark_entry_cache = KMEM_CACHE(dnotify_mark_entry, SLAB_PANIC); + + dnotify_group = fsnotify_obtain_group(DNOTIFY_GROUP_NUM, + 0, &dnotify_fsnotify_ops); + if (IS_ERR(dnotify_group)) + panic("unable to allocate fsnotify group for dnotify\n"); + return 0; +} + +module_init(dnotify_init) diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c new file mode 100644 index 00000000000..037e878e03f --- /dev/null +++ b/fs/notify/fsnotify.c @@ -0,0 +1,188 @@ +/* + * 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" + +/* + * Clear all of the marks on an inode when it is being evicted from core + */ +void __fsnotify_inode_delete(struct inode *inode) +{ + fsnotify_clear_marks_by_inode(inode); +} +EXPORT_SYMBOL_GPL(__fsnotify_inode_delete); + +/* + * Given an inode, first check if we care what happens to our children. Inotify + * and dnotify both tell their parents about events. If we care about any event + * on a child we run all of our children and set a dentry flag saying that the + * parent cares. Thus when an event happens on a child it can quickly tell if + * if there is a need to find a parent and send the event to the parent. + */ +void __fsnotify_update_child_dentry_flags(struct inode *inode) +{ + struct dentry *alias; + int watched; + + if (!S_ISDIR(inode->i_mode)) + return; + + /* determine if the children should tell inode about their events */ + watched = fsnotify_inode_watches_children(inode); + + spin_lock(&dcache_lock); + /* run all of the dentries associated with this inode. Since this is a + * directory, there damn well better only be one item on this list */ + list_for_each_entry(alias, &inode->i_dentry, d_alias) { + struct dentry *child; + + /* run all of the children of the original inode and fix their + * d_flags to indicate parental interest (their parent is the + * original inode) */ + 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_FSNOTIFY_PARENT_WATCHED; + else + child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; + spin_unlock(&child->d_lock); + } + } + spin_unlock(&dcache_lock); +} + +/* Notify this dentry's parent about a child's events. */ +void __fsnotify_parent(struct dentry *dentry, __u32 mask) +{ + struct dentry *parent; + struct inode *p_inode; + bool send = false; + bool should_update_children = false; + + if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) + return; + + spin_lock(&dentry->d_lock); + parent = dentry->d_parent; + p_inode = parent->d_inode; + + if (fsnotify_inode_watches_children(p_inode)) { + if (p_inode->i_fsnotify_mask & mask) { + dget(parent); + send = true; + } + } else { + /* + * The parent doesn't care about events on it's children but + * at least one child thought it did. We need to run all the + * children and update their d_flags to let them know p_inode + * doesn't care about them any more. + */ + dget(parent); + should_update_children = true; + } + + spin_unlock(&dentry->d_lock); + + if (send) { + /* we are notifying a parent so come up with the new mask which + * specifies these are events which came from a child. */ + mask |= FS_EVENT_ON_CHILD; + + fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, + dentry->d_name.name, 0); + dput(parent); + } + + if (unlikely(should_update_children)) { + __fsnotify_update_child_dentry_flags(p_inode); + dput(parent); + } +} +EXPORT_SYMBOL_GPL(__fsnotify_parent); + +/* + * 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, const char *file_name, u32 cookie) +{ + struct fsnotify_group *group; + struct fsnotify_event *event = NULL; + int idx; + /* global tests shouldn't care about events on child only the specific event */ + __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); + + if (list_empty(&fsnotify_groups)) + return; + + if (!(test_mask & fsnotify_mask)) + return; + + if (!(test_mask & to_tell->i_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 (test_mask & group->mask) { + if (!group->ops->should_send_event(group, to_tell, mask)) + continue; + if (!event) { + event = fsnotify_create_event(to_tell, mask, data, + data_is, file_name, cookie, + GFP_KERNEL); + /* 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 00000000000..4dc240824b2 --- /dev/null +++ b/fs/notify/fsnotify.h @@ -0,0 +1,34 @@ +#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; + +/* destroy all events sitting in this groups notification queue */ +extern void fsnotify_flush_notify(struct fsnotify_group *group); + +/* final kfree of a group */ +extern void fsnotify_final_destroy_group(struct fsnotify_group *group); + +/* run the list of all marks associated with inode and flag them to be freed */ +extern void fsnotify_clear_marks_by_inode(struct inode *inode); +/* + * update the dentry->d_flags of all of inode's children to indicate if inode cares + * about events that happen to its children. + */ +extern void __fsnotify_update_child_dentry_flags(struct inode *inode); + +/* allocate and destroy and event holder to attach events to notification/access queues */ +extern struct fsnotify_event_holder *fsnotify_alloc_event_holder(void); +extern void fsnotify_destroy_event_holder(struct fsnotify_event_holder *holder); + +#endif /* __FS_NOTIFY_FSNOTIFY_H_ */ diff --git a/fs/notify/group.c b/fs/notify/group.c new file mode 100644 index 00000000000..0e1677144bc --- /dev/null +++ b/fs/notify/group.c @@ -0,0 +1,254 @@ +/* + * 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; +} + +/* + * Update the group->mask by running all of the marks associated with this + * group and finding the bitwise | of all of the mark->mask. If we change + * the group->mask we need to update the global mask of events interesting + * to the system. + */ +void fsnotify_recalc_group_mask(struct fsnotify_group *group) +{ + __u32 mask = 0; + __u32 old_mask = group->mask; + struct fsnotify_mark_entry *entry; + + spin_lock(&group->mark_lock); + list_for_each_entry(entry, &group->mark_entries, g_list) + mask |= entry->mask; + spin_unlock(&group->mark_lock); + + group->mask = mask; + + if (old_mask != mask) + fsnotify_recalc_global_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 + */ +void fsnotify_final_destroy_group(struct fsnotify_group *group) +{ + /* clear the notification queue of all events */ + fsnotify_flush_notify(group); + + if (group->ops->free_group_priv) + group->ops->free_group_priv(group); + + kfree(group); +} + +/* + * Trying to get rid of a group. We need to first get rid of any outstanding + * allocations and then free the group. Remember that fsnotify_clear_marks_by_group + * could miss marks that are being freed by inode and those marks could still + * hold a reference to this group (via group->num_marks) If we get into that + * situtation, the fsnotify_final_destroy_group will get called when that final + * mark is freed. + */ +static void fsnotify_destroy_group(struct fsnotify_group *group) +{ + /* clear all inode mark entries for this group */ + fsnotify_clear_marks_by_group(group); + + /* past the point of no return, matches the initial value of 1 */ + if (atomic_dec_and_test(&group->num_marks)) + fsnotify_final_destroy_group(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; + + mutex_init(&group->notification_mutex); + INIT_LIST_HEAD(&group->notification_list); + init_waitqueue_head(&group->notification_waitq); + group->q_len = 0; + group->max_events = UINT_MAX; + + spin_lock_init(&group->mark_lock); + atomic_set(&group->num_marks, 0); + INIT_LIST_HEAD(&group->mark_entries); + + 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; + /* being on the fsnotify_groups list holds one num_marks */ + atomic_inc(&group->num_marks); + + mutex_unlock(&fsnotify_grp_mutex); + + if (mask) + fsnotify_recalc_global_mask(); + + return group; +} diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c new file mode 100644 index 00000000000..3165d85aada --- /dev/null +++ b/fs/notify/inode_mark.c @@ -0,0 +1,426 @@ +/* + * 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. + */ + +/* + * fsnotify inode mark locking/lifetime/and refcnting + * + * REFCNT: + * The mark->refcnt tells how many "things" in the kernel currently are + * referencing this object. The object typically will live inside the kernel + * with a refcnt of 2, one for each list it is on (i_list, g_list). Any task + * which can find this object holding the appropriete locks, can take a reference + * and the object itself is guarenteed to survive until the reference is dropped. + * + * LOCKING: + * There are 3 spinlocks involved with fsnotify inode marks and they MUST + * be taken in order as follows: + * + * entry->lock + * group->mark_lock + * inode->i_lock + * + * entry->lock protects 2 things, entry->group and entry->inode. You must hold + * that lock to dereference either of these things (they could be NULL even with + * the lock) + * + * group->mark_lock protects the mark_entries list anchored inside a given group + * and each entry is hooked via the g_list. It also sorta protects the + * free_g_list, which when used is anchored by a private list on the stack of the + * task which held the group->mark_lock. + * + * inode->i_lock protects the i_fsnotify_mark_entries list anchored inside a + * given inode and each entry is hooked via the i_list. (and sorta the + * free_i_list) + * + * + * LIFETIME: + * Inode marks survive between when they are added to an inode and when their + * refcnt==0. + * + * The inode mark can be cleared for a number of different reasons including: + * - The inode is unlinked for the last time. (fsnotify_inode_remove) + * - The inode is being evicted from cache. (fsnotify_inode_delete) + * - The fs the inode is on is unmounted. (fsnotify_inode_delete/fsnotify_unmount_inodes) + * - Something explicitly requests that it be removed. (fsnotify_destroy_mark_by_entry) + * - The fsnotify_group associated with the mark is going away and all such marks + * need to be cleaned up. (fsnotify_clear_marks_by_group) + * + * Worst case we are given an inode and need to clean up all the marks on that + * inode. We take i_lock and walk the i_fsnotify_mark_entries safely. For each + * mark on the list we take a reference (so the mark can't disappear under us). + * We remove that mark form the inode's list of marks and we add this mark to a + * private list anchored on the stack using i_free_list; At this point we no + * longer fear anything finding the mark using the inode's list of marks. + * + * We can safely and locklessly run the private list on the stack of everything + * we just unattached from the original inode. For each mark on the private list + * we grab the mark-> and can thus dereference mark->group and mark->inode. If + * we see the group and inode are not NULL we take those locks. Now holding all + * 3 locks we can completely remove the mark from other tasks finding it in the + * future. Remember, 10 things might already be referencing this mark, but they + * better be holding a ref. We drop our reference we took before we unhooked it + * from the inode. When the ref hits 0 we can free the mark. + * + * Very similarly for freeing by group, except we use free_g_list. + * + * This has the very interesting property of being able to run concurrently with + * any (or all) other directions. + */ + +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/writeback.h> /* for inode_lock */ + +#include <asm/atomic.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +void fsnotify_get_mark(struct fsnotify_mark_entry *entry) +{ + atomic_inc(&entry->refcnt); +} + +void fsnotify_put_mark(struct fsnotify_mark_entry *entry) +{ + if (atomic_dec_and_test(&entry->refcnt)) + entry->free_mark(entry); +} + +/* + * Recalculate the mask of events relevant to a given inode locked. + */ +static void fsnotify_recalc_inode_mask_locked(struct inode *inode) +{ + struct fsnotify_mark_entry *entry; + struct hlist_node *pos; + __u32 new_mask = 0; + + assert_spin_locked(&inode->i_lock); + + hlist_for_each_entry(entry, pos, &inode->i_fsnotify_mark_entries, i_list) + new_mask |= entry->mask; + inode->i_fsnotify_mask = new_mask; +} + +/* + * Recalculate the inode->i_fsnotify_mask, or the mask of all FS_* event types + * any notifier is interested in hearing for this inode. + */ +void fsnotify_recalc_inode_mask(struct inode *inode) +{ + spin_lock(&inode->i_lock); + fsnotify_recalc_inode_mask_locked(inode); + spin_unlock(&inode->i_lock); + + __fsnotify_update_child_dentry_flags(inode); +} + +/* + * Any time a mark is getting freed we end up here. + * The caller had better be holding a reference to this mark so we don't actually + * do the final put under the entry->lock + */ +void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry) +{ + struct fsnotify_group *group; + struct inode *inode; + + spin_lock(&entry->lock); + + group = entry->group; + inode = entry->inode; + + BUG_ON(group && !inode); + BUG_ON(!group && inode); + + /* if !group something else already marked this to die */ + if (!group) { + spin_unlock(&entry->lock); + return; + } + + /* 1 from caller and 1 for being on i_list/g_list */ + BUG_ON(atomic_read(&entry->refcnt) < 2); + + spin_lock(&group->mark_lock); + spin_lock(&inode->i_lock); + + hlist_del_init(&entry->i_list); + entry->inode = NULL; + + list_del_init(&entry->g_list); + entry->group = NULL; + + fsnotify_put_mark(entry); /* for i_list and g_list */ + + /* + * this mark is now off the inode->i_fsnotify_mark_entries list and we + * hold the inode->i_lock, so this is the perfect time to update the + * inode->i_fsnotify_mask + */ + fsnotify_recalc_inode_mask_locked(inode); + + spin_unlock(&inode->i_lock); + spin_unlock(&group->mark_lock); + spin_unlock(&entry->lock); + + /* + * Some groups like to know that marks are being freed. This is a + * callback to the group function to let it know that this entry + * is being freed. + */ + if (group->ops->freeing_mark) + group->ops->freeing_mark(entry, group); + + /* + * __fsnotify_update_child_dentry_flags(inode); + * + * I really want to call that, but we can't, we have no idea if the inode + * still exists the second we drop the entry->lock. + * + * The next time an event arrive to this inode from one of it's children + * __fsnotify_parent will see that the inode doesn't care about it's + * children and will update all of these flags then. So really this + * is just a lazy update (and could be a perf win...) + */ + + + iput(inode); + + /* + * it's possible that this group tried to destroy itself, but this + * this mark was simultaneously being freed by inode. If that's the + * case, we finish freeing the group here. + */ + if (unlikely(atomic_dec_and_test(&group->num_marks))) + fsnotify_final_destroy_group(group); +} + +/* + * Given a group, destroy all of the marks associated with that group. + */ +void fsnotify_clear_marks_by_group(struct fsnotify_group *group) +{ + struct fsnotify_mark_entry *lentry, *entry; + LIST_HEAD(free_list); + + spin_lock(&group->mark_lock); + list_for_each_entry_safe(entry, lentry, &group->mark_entries, g_list) { + list_add(&entry->free_g_list, &free_list); + list_del_init(&entry->g_list); + fsnotify_get_mark(entry); + } + spin_unlock(&group->mark_lock); + + list_for_each_entry_safe(entry, lentry, &free_list, free_g_list) { + fsnotify_destroy_mark_by_entry(entry); + fsnotify_put_mark(entry); + } +} + +/* + * Given an inode, destroy all of the marks associated with that inode. + */ +void fsnotify_clear_marks_by_inode(struct inode *inode) +{ + struct fsnotify_mark_entry *entry, *lentry; + struct hlist_node *pos, *n; + LIST_HEAD(free_list); + + spin_lock(&inode->i_lock); + hlist_for_each_entry_safe(entry, pos, n, &inode->i_fsnotify_mark_entries, i_list) { + list_add(&entry->free_i_list, &free_list); + hlist_del_init(&entry->i_list); + fsnotify_get_mark(entry); + } + spin_unlock(&inode->i_lock); + + list_for_each_entry_safe(entry, lentry, &free_list, free_i_list) { + fsnotify_destroy_mark_by_entry(entry); + fsnotify_put_mark(entry); + } +} + +/* + * given a group and inode, find the mark associated with that combination. + * if found take a reference to that mark and return it, else return NULL + */ +struct fsnotify_mark_entry *fsnotify_find_mark_entry(struct fsnotify_group *group, + struct inode *inode) +{ + struct fsnotify_mark_entry *entry; + struct hlist_node *pos; + + assert_spin_locked(&inode->i_lock); + + hlist_for_each_entry(entry, pos, &inode->i_fsnotify_mark_entries, i_list) { + if (entry->group == group) { + fsnotify_get_mark(entry); + return entry; + } + } + return NULL; +} + +/* + * Nothing fancy, just initialize lists and locks and counters. + */ +void fsnotify_init_mark(struct fsnotify_mark_entry *entry, + void (*free_mark)(struct fsnotify_mark_entry *entry)) + +{ + spin_lock_init(&entry->lock); + atomic_set(&entry->refcnt, 1); + INIT_HLIST_NODE(&entry->i_list); + entry->group = NULL; + entry->mask = 0; + entry->inode = NULL; + entry->free_mark = free_mark; +} + +/* + * Attach an initialized mark entry to a given group and inode. + * These marks may be used for the fsnotify backend to determine which + * event types should be delivered to which group and for which inodes. + */ +int fsnotify_add_mark(struct fsnotify_mark_entry *entry, + struct fsnotify_group *group, struct inode *inode) +{ + struct fsnotify_mark_entry *lentry; + int ret = 0; + + inode = igrab(inode); + if (unlikely(!inode)) + return -EINVAL; + + /* + * LOCKING ORDER!!!! + * entry->lock + * group->mark_lock + * inode->i_lock + */ + spin_lock(&entry->lock); + spin_lock(&group->mark_lock); + spin_lock(&inode->i_lock); + + lentry = fsnotify_find_mark_entry(group, inode); + if (!lentry) { + entry->group = group; + entry->inode = inode; + + hlist_add_head(&entry->i_list, &inode->i_fsnotify_mark_entries); + list_add(&entry->g_list, &group->mark_entries); + + fsnotify_get_mark(entry); /* for i_list and g_list */ + + atomic_inc(&group->num_marks); + + fsnotify_recalc_inode_mask_locked(inode); + } + + spin_unlock(&inode->i_lock); + spin_unlock(&group->mark_lock); + spin_unlock(&entry->lock); + + if (lentry) { + ret = -EEXIST; + iput(inode); + fsnotify_put_mark(lentry); + } else { + __fsnotify_update_child_dentry_flags(inode); + } + + return ret; +} + +/** + * fsnotify_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 fsnotify_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 inode *need_iput_tmp; + + /* + * We cannot __iget() an inode in state I_CLEAR, I_FREEING, + * I_WILL_FREE, or I_NEW 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|I_NEW)) + continue; + + /* + * 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; + + need_iput_tmp = need_iput; + need_iput = NULL; + + /* In case fsnotify_inode_delete() 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 FS_UNMOUNT and then remove it */ + fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0); + + fsnotify_inode_delete(inode); + + iput(inode); + + spin_lock(&inode_lock); + } +} diff --git a/fs/notify/inotify/Kconfig b/fs/notify/inotify/Kconfig new file mode 100644 index 00000000000..3e56dbffe72 --- /dev/null +++ b/fs/notify/inotify/Kconfig @@ -0,0 +1,31 @@ +config INOTIFY + bool "Inotify file change notification support" + default n + ---help--- + Say Y here to enable legacy in kernel inotify support. Inotify is a + file change notification system. It is a replacement for dnotify. + This option only provides the legacy inotify in kernel API. There + are no in tree kernel users of this interface since it is deprecated. + You only need this if you are loading an out of tree kernel module + that uses inotify. + + For more information, see <file:Documentation/filesystems/inotify.txt> + + If unsure, say N. + +config INOTIFY_USER + bool "Inotify support for userspace" + select FSNOTIFY + 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. + 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. diff --git a/fs/notify/inotify/Makefile b/fs/notify/inotify/Makefile new file mode 100644 index 00000000000..94382817136 --- /dev/null +++ b/fs/notify/inotify/Makefile @@ -0,0 +1,2 @@ +obj-$(CONFIG_INOTIFY) += inotify.o +obj-$(CONFIG_INOTIFY_USER) += inotify_fsnotify.o inotify_user.o diff --git a/fs/notify/inotify/inotify.c b/fs/notify/inotify/inotify.c new file mode 100644 index 00000000000..40b1cf914cc --- /dev/null +++ b/fs/notify/inotify/inotify.c @@ -0,0 +1,933 @@ +/* + * 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> +#include <linux/fsnotify_backend.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_NOFS))) + 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; + + /* + * We cannot __iget() an inode in state I_CLEAR, I_FREEING, + * I_WILL_FREE, or I_NEW 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|I_NEW)) + continue; + + /* + * 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; + + 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) +{ + 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; +} + +module_init(inotify_setup); diff --git a/fs/notify/inotify/inotify.h b/fs/notify/inotify/inotify.h new file mode 100644 index 00000000000..f234f3a4c8c --- /dev/null +++ b/fs/notify/inotify/inotify.h @@ -0,0 +1,22 @@ +#include <linux/fsnotify_backend.h> +#include <linux/inotify.h> +#include <linux/slab.h> /* struct kmem_cache */ + +extern struct kmem_cache *event_priv_cachep; + +struct inotify_event_private_data { + struct fsnotify_event_private_data fsnotify_event_priv_data; + int wd; +}; + +struct inotify_inode_mark_entry { + /* fsnotify_mark_entry MUST be the first thing */ + struct fsnotify_mark_entry fsn_entry; + int wd; +}; + +extern void inotify_ignored_and_remove_idr(struct fsnotify_mark_entry *entry, + struct fsnotify_group *group); +extern void inotify_free_event_priv(struct fsnotify_event_private_data *event_priv); + +extern const struct fsnotify_ops inotify_fsnotify_ops; diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c new file mode 100644 index 00000000000..e27960cd76a --- /dev/null +++ b/fs/notify/inotify/inotify_fsnotify.c @@ -0,0 +1,170 @@ +/* + * 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. + * + * Copyright (C) 2009 Eric Paris <Red Hat Inc> + * inotify was largely rewriten to make use of the fsnotify infrastructure + * + * 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> /* struct inode */ +#include <linux/fsnotify_backend.h> +#include <linux/inotify.h> +#include <linux/path.h> /* struct path */ +#include <linux/slab.h> /* kmem_* */ +#include <linux/types.h> +#include <linux/sched.h> + +#include "inotify.h" + +static int inotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event) +{ + struct fsnotify_mark_entry *entry; + struct inotify_inode_mark_entry *ientry; + struct inode *to_tell; + struct inotify_event_private_data *event_priv; + struct fsnotify_event_private_data *fsn_event_priv; + int wd, ret; + + to_tell = event->to_tell; + + spin_lock(&to_tell->i_lock); + entry = fsnotify_find_mark_entry(group, to_tell); + spin_unlock(&to_tell->i_lock); + /* race with watch removal? We already passes should_send */ + if (unlikely(!entry)) + return 0; + ientry = container_of(entry, struct inotify_inode_mark_entry, + fsn_entry); + wd = ientry->wd; + + event_priv = kmem_cache_alloc(event_priv_cachep, GFP_KERNEL); + if (unlikely(!event_priv)) + return -ENOMEM; + + fsn_event_priv = &event_priv->fsnotify_event_priv_data; + + fsn_event_priv->group = group; + event_priv->wd = wd; + + ret = fsnotify_add_notify_event(group, event, fsn_event_priv); + if (ret) { + inotify_free_event_priv(fsn_event_priv); + /* EEXIST says we tail matched, EOVERFLOW isn't something + * to report up the stack. */ + if ((ret == -EEXIST) || + (ret == -EOVERFLOW)) + ret = 0; + } + + /* + * If we hold the entry until after the event is on the queue + * IN_IGNORED won't be able to pass this event in the queue + */ + fsnotify_put_mark(entry); + + return ret; +} + +static void inotify_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group) +{ + inotify_ignored_and_remove_idr(entry, group); +} + +static bool inotify_should_send_event(struct fsnotify_group *group, struct inode *inode, __u32 mask) +{ + struct fsnotify_mark_entry *entry; + bool send; + + spin_lock(&inode->i_lock); + entry = fsnotify_find_mark_entry(group, inode); + spin_unlock(&inode->i_lock); + if (!entry) + return false; + + mask = (mask & ~FS_EVENT_ON_CHILD); + send = (entry->mask & mask); + + /* find took a reference */ + fsnotify_put_mark(entry); + + return send; +} + +/* + * This is NEVER supposed to be called. Inotify marks should either have been + * removed from the idr when the watch was removed or in the + * fsnotify_destroy_mark_by_group() call when the inotify instance was being + * torn down. This is only called if the idr is about to be freed but there + * are still marks in it. + */ +static int idr_callback(int id, void *p, void *data) +{ + struct fsnotify_mark_entry *entry; + struct inotify_inode_mark_entry *ientry; + static bool warned = false; + + if (warned) + return 0; + + warned = true; + entry = p; + ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry); + + WARN(1, "inotify closing but id=%d for entry=%p in group=%p still in " + "idr. Probably leaking memory\n", id, p, data); + + /* + * I'm taking the liberty of assuming that the mark in question is a + * valid address and I'm dereferencing it. This might help to figure + * out why we got here and the panic is no worse than the original + * BUG() that was here. + */ + if (entry) + printk(KERN_WARNING "entry->group=%p inode=%p wd=%d\n", + entry->group, entry->inode, ientry->wd); + return 0; +} + +static void inotify_free_group_priv(struct fsnotify_group *group) +{ + /* ideally the idr is empty and we won't hit the BUG in teh callback */ + idr_for_each(&group->inotify_data.idr, idr_callback, group); + idr_remove_all(&group->inotify_data.idr); + idr_destroy(&group->inotify_data.idr); + free_uid(group->inotify_data.user); +} + +void inotify_free_event_priv(struct fsnotify_event_private_data *fsn_event_priv) +{ + struct inotify_event_private_data *event_priv; + + + event_priv = container_of(fsn_event_priv, struct inotify_event_private_data, + fsnotify_event_priv_data); + + kmem_cache_free(event_priv_cachep, event_priv); +} + +const struct fsnotify_ops inotify_fsnotify_ops = { + .handle_event = inotify_handle_event, + .should_send_event = inotify_should_send_event, + .free_group_priv = inotify_free_group_priv, + .free_event_priv = inotify_free_event_priv, + .freeing_mark = inotify_freeing_mark, +}; diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c new file mode 100644 index 00000000000..75aa15a0be8 --- /dev/null +++ b/fs/notify/inotify/inotify_user.c @@ -0,0 +1,829 @@ +/* + * 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. + * + * Copyright (C) 2009 Eric Paris <Red Hat Inc> + * inotify was largely rewriten to make use of the fsnotify infrastructure + * + * 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/file.h> +#include <linux/fs.h> /* struct inode */ +#include <linux/fsnotify_backend.h> +#include <linux/idr.h> +#include <linux/init.h> /* module_init */ +#include <linux/inotify.h> +#include <linux/kernel.h> /* roundup() */ +#include <linux/magic.h> /* superblock magic number */ +#include <linux/mount.h> /* mntget */ +#include <linux/namei.h> /* LOOKUP_FOLLOW */ +#include <linux/path.h> /* struct path */ +#include <linux/sched.h> /* struct user */ +#include <linux/slab.h> /* struct kmem_cache */ +#include <linux/syscalls.h> +#include <linux/types.h> +#include <linux/uaccess.h> +#include <linux/poll.h> +#include <linux/wait.h> + +#include "inotify.h" + +#include <asm/ioctls.h> + +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_queued_events __read_mostly; +int inotify_max_user_watches __read_mostly; + +static struct kmem_cache *inotify_inode_mark_cachep __read_mostly; +struct kmem_cache *event_priv_cachep __read_mostly; + +/* + * When inotify registers a new group it increments this and uses that + * value as an offset to set the fsnotify group "name" and priority. + */ +static atomic_t inotify_grp_num; + +#ifdef CONFIG_SYSCTL + +#include <linux/sysctl.h> + +static int zero; + +ctl_table inotify_table[] = { + { + .procname = "max_user_instances", + .data = &inotify_max_user_instances, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + }, + { + .procname = "max_user_watches", + .data = &inotify_max_user_watches, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + }, + { + .procname = "max_queued_events", + .data = &inotify_max_queued_events, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero + }, + { } +}; +#endif /* CONFIG_SYSCTL */ + +static inline __u32 inotify_arg_to_mask(u32 arg) +{ + __u32 mask; + + /* everything should accept their own ignored and cares about children */ + mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD); + + /* mask off the flags used to open the fd */ + mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT)); + + return mask; +} + +static inline u32 inotify_mask_to_arg(__u32 mask) +{ + return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED | + IN_Q_OVERFLOW); +} + +/* intofiy userspace file descriptor functions */ +static unsigned int inotify_poll(struct file *file, poll_table *wait) +{ + struct fsnotify_group *group = file->private_data; + int ret = 0; + + poll_wait(file, &group->notification_waitq, wait); + mutex_lock(&group->notification_mutex); + if (!fsnotify_notify_queue_is_empty(group)) + ret = POLLIN | POLLRDNORM; + mutex_unlock(&group->notification_mutex); + + return ret; +} + +/* + * Get an inotify_kernel_event if one exists and is small + * enough to fit in "count". Return an error pointer if + * not large enough. + * + * Called with the group->notification_mutex held. + */ +static struct fsnotify_event *get_one_event(struct fsnotify_group *group, + size_t count) +{ + size_t event_size = sizeof(struct inotify_event); + struct fsnotify_event *event; + + if (fsnotify_notify_queue_is_empty(group)) + return NULL; + + event = fsnotify_peek_notify_event(group); + + if (event->name_len) + event_size += roundup(event->name_len + 1, event_size); + + if (event_size > count) + return ERR_PTR(-EINVAL); + + /* held the notification_mutex the whole time, so this is the + * same event we peeked above */ + fsnotify_remove_notify_event(group); + + return event; +} + +/* + * Copy an event to user space, returning how much we copied. + * + * We already checked that the event size is smaller than the + * buffer we had in "get_one_event()" above. + */ +static ssize_t copy_event_to_user(struct fsnotify_group *group, + struct fsnotify_event *event, + char __user *buf) +{ + struct inotify_event inotify_event; + struct fsnotify_event_private_data *fsn_priv; + struct inotify_event_private_data *priv; + size_t event_size = sizeof(struct inotify_event); + size_t name_len = 0; + + /* we get the inotify watch descriptor from the event private data */ + spin_lock(&event->lock); + fsn_priv = fsnotify_remove_priv_from_event(group, event); + spin_unlock(&event->lock); + + if (!fsn_priv) + inotify_event.wd = -1; + else { + priv = container_of(fsn_priv, struct inotify_event_private_data, + fsnotify_event_priv_data); + inotify_event.wd = priv->wd; + inotify_free_event_priv(fsn_priv); + } + + /* + * round up event->name_len so it is a multiple of event_size + * plus an extra byte for the terminating '\0'. + */ + if (event->name_len) + name_len = roundup(event->name_len + 1, event_size); + inotify_event.len = name_len; + + inotify_event.mask = inotify_mask_to_arg(event->mask); + inotify_event.cookie = event->sync_cookie; + + /* send the main event */ + if (copy_to_user(buf, &inotify_event, event_size)) + return -EFAULT; + + buf += event_size; + + /* + * fsnotify only stores the pathname, so here we have to send the pathname + * and then pad that pathname out to a multiple of sizeof(inotify_event) + * with zeros. I get my zeros from the nul_inotify_event. + */ + if (name_len) { + unsigned int len_to_zero = name_len - event->name_len; + /* copy the path name */ + if (copy_to_user(buf, event->file_name, event->name_len)) + return -EFAULT; + buf += event->name_len; + + /* fill userspace with 0's */ + if (clear_user(buf, len_to_zero)) + return -EFAULT; + buf += len_to_zero; + event_size += name_len; + } + + return event_size; +} + +static ssize_t inotify_read(struct file *file, char __user *buf, + size_t count, loff_t *pos) +{ + struct fsnotify_group *group; + struct fsnotify_event *kevent; + char __user *start; + int ret; + DEFINE_WAIT(wait); + + start = buf; + group = file->private_data; + + while (1) { + prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE); + + mutex_lock(&group->notification_mutex); + kevent = get_one_event(group, count); + mutex_unlock(&group->notification_mutex); + + if (kevent) { + ret = PTR_ERR(kevent); + if (IS_ERR(kevent)) + break; + ret = copy_event_to_user(group, kevent, buf); + fsnotify_put_event(kevent); + if (ret < 0) + break; + buf += ret; + count -= ret; + continue; + } + + ret = -EAGAIN; + if (file->f_flags & O_NONBLOCK) + break; + ret = -EINTR; + if (signal_pending(current)) + break; + + if (start != buf) + break; + + schedule(); + } + + finish_wait(&group->notification_waitq, &wait); + if (start != buf && ret != -EFAULT) + ret = buf - start; + return ret; +} + +static int inotify_fasync(int fd, struct file *file, int on) +{ + struct fsnotify_group *group = file->private_data; + + return fasync_helper(fd, file, on, &group->inotify_data.fa) >= 0 ? 0 : -EIO; +} + +static int inotify_release(struct inode *ignored, struct file *file) +{ + struct fsnotify_group *group = file->private_data; + struct user_struct *user = group->inotify_data.user; + + fsnotify_clear_marks_by_group(group); + + /* free this group, matching get was inotify_init->fsnotify_obtain_group */ + fsnotify_put_group(group); + + atomic_dec(&user->inotify_devs); + + return 0; +} + +static long inotify_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + struct fsnotify_group *group; + struct fsnotify_event_holder *holder; + struct fsnotify_event *event; + void __user *p; + int ret = -ENOTTY; + size_t send_len = 0; + + group = file->private_data; + p = (void __user *) arg; + + switch (cmd) { + case FIONREAD: + mutex_lock(&group->notification_mutex); + list_for_each_entry(holder, &group->notification_list, event_list) { + event = holder->event; + send_len += sizeof(struct inotify_event); + if (event->name_len) + send_len += roundup(event->name_len + 1, + sizeof(struct inotify_event)); + } + mutex_unlock(&group->notification_mutex); + ret = put_user(send_len, (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, +}; + + +/* + * find_inode - resolve a user-given path to a specific inode + */ +static int inotify_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; +} + +/* + * Remove the mark from the idr (if present) and drop the reference + * on the mark because it was in the idr. + */ +static void inotify_remove_from_idr(struct fsnotify_group *group, + struct inotify_inode_mark_entry *ientry) +{ + struct idr *idr; + struct fsnotify_mark_entry *entry; + struct inotify_inode_mark_entry *found_ientry; + int wd; + + spin_lock(&group->inotify_data.idr_lock); + idr = &group->inotify_data.idr; + wd = ientry->wd; + + if (wd == -1) + goto out; + + entry = idr_find(&group->inotify_data.idr, wd); + if (unlikely(!entry)) + goto out; + + found_ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry); + if (unlikely(found_ientry != ientry)) { + /* We found an entry in the idr with the right wd, but it's + * not the entry we were told to remove. eparis seriously + * fucked up somewhere. */ + WARN_ON(1); + ientry->wd = -1; + goto out; + } + + /* One ref for being in the idr, one ref held by the caller */ + BUG_ON(atomic_read(&entry->refcnt) < 2); + + idr_remove(idr, wd); + ientry->wd = -1; + + /* removed from the idr, drop that ref */ + fsnotify_put_mark(entry); +out: + spin_unlock(&group->inotify_data.idr_lock); +} + +/* + * Send IN_IGNORED for this wd, remove this wd from the idr. + */ +void inotify_ignored_and_remove_idr(struct fsnotify_mark_entry *entry, + struct fsnotify_group *group) +{ + struct inotify_inode_mark_entry *ientry; + struct fsnotify_event *ignored_event; + struct inotify_event_private_data *event_priv; + struct fsnotify_event_private_data *fsn_event_priv; + int ret; + + ignored_event = fsnotify_create_event(NULL, FS_IN_IGNORED, NULL, + FSNOTIFY_EVENT_NONE, NULL, 0, + GFP_NOFS); + if (!ignored_event) + return; + + ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry); + + event_priv = kmem_cache_alloc(event_priv_cachep, GFP_NOFS); + if (unlikely(!event_priv)) + goto skip_send_ignore; + + fsn_event_priv = &event_priv->fsnotify_event_priv_data; + + fsn_event_priv->group = group; + event_priv->wd = ientry->wd; + + ret = fsnotify_add_notify_event(group, ignored_event, fsn_event_priv); + if (ret) + inotify_free_event_priv(fsn_event_priv); + +skip_send_ignore: + + /* matches the reference taken when the event was created */ + fsnotify_put_event(ignored_event); + + /* remove this entry from the idr */ + inotify_remove_from_idr(group, ientry); + + atomic_dec(&group->inotify_data.user->inotify_watches); +} + +/* ding dong the mark is dead */ +static void inotify_free_mark(struct fsnotify_mark_entry *entry) +{ + struct inotify_inode_mark_entry *ientry = (struct inotify_inode_mark_entry *)entry; + + kmem_cache_free(inotify_inode_mark_cachep, ientry); +} + +static int inotify_update_existing_watch(struct fsnotify_group *group, + struct inode *inode, + u32 arg) +{ + struct fsnotify_mark_entry *entry; + struct inotify_inode_mark_entry *ientry; + __u32 old_mask, new_mask; + __u32 mask; + int add = (arg & IN_MASK_ADD); + int ret; + + /* don't allow invalid bits: we don't want flags set */ + mask = inotify_arg_to_mask(arg); + if (unlikely(!mask)) + return -EINVAL; + + spin_lock(&inode->i_lock); + entry = fsnotify_find_mark_entry(group, inode); + spin_unlock(&inode->i_lock); + if (!entry) + return -ENOENT; + + ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry); + + spin_lock(&entry->lock); + + old_mask = entry->mask; + if (add) { + entry->mask |= mask; + new_mask = entry->mask; + } else { + entry->mask = mask; + new_mask = entry->mask; + } + + spin_unlock(&entry->lock); + + if (old_mask != new_mask) { + /* more bits in old than in new? */ + int dropped = (old_mask & ~new_mask); + /* more bits in this entry than the inode's mask? */ + int do_inode = (new_mask & ~inode->i_fsnotify_mask); + /* more bits in this entry than the group? */ + int do_group = (new_mask & ~group->mask); + + /* update the inode with this new entry */ + if (dropped || do_inode) + fsnotify_recalc_inode_mask(inode); + + /* update the group mask with the new mask */ + if (dropped || do_group) + fsnotify_recalc_group_mask(group); + } + + /* return the wd */ + ret = ientry->wd; + + /* match the get from fsnotify_find_mark_entry() */ + fsnotify_put_mark(entry); + + return ret; +} + +static int inotify_new_watch(struct fsnotify_group *group, + struct inode *inode, + u32 arg) +{ + struct inotify_inode_mark_entry *tmp_ientry; + __u32 mask; + int ret; + + /* don't allow invalid bits: we don't want flags set */ + mask = inotify_arg_to_mask(arg); + if (unlikely(!mask)) + return -EINVAL; + + tmp_ientry = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL); + if (unlikely(!tmp_ientry)) + return -ENOMEM; + + fsnotify_init_mark(&tmp_ientry->fsn_entry, inotify_free_mark); + tmp_ientry->fsn_entry.mask = mask; + tmp_ientry->wd = -1; + + ret = -ENOSPC; + if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches) + goto out_err; +retry: + ret = -ENOMEM; + if (unlikely(!idr_pre_get(&group->inotify_data.idr, GFP_KERNEL))) + goto out_err; + + /* we are putting the mark on the idr, take a reference */ + fsnotify_get_mark(&tmp_ientry->fsn_entry); + + spin_lock(&group->inotify_data.idr_lock); + ret = idr_get_new_above(&group->inotify_data.idr, &tmp_ientry->fsn_entry, + group->inotify_data.last_wd+1, + &tmp_ientry->wd); + spin_unlock(&group->inotify_data.idr_lock); + if (ret) { + /* we didn't get on the idr, drop the idr reference */ + fsnotify_put_mark(&tmp_ientry->fsn_entry); + + /* idr was out of memory allocate and try again */ + if (ret == -EAGAIN) + goto retry; + goto out_err; + } + + /* we are on the idr, now get on the inode */ + ret = fsnotify_add_mark(&tmp_ientry->fsn_entry, group, inode); + if (ret) { + /* we failed to get on the inode, get off the idr */ + inotify_remove_from_idr(group, tmp_ientry); + goto out_err; + } + + /* update the idr hint, who cares about races, it's just a hint */ + group->inotify_data.last_wd = tmp_ientry->wd; + + /* increment the number of watches the user has */ + atomic_inc(&group->inotify_data.user->inotify_watches); + + /* return the watch descriptor for this new entry */ + ret = tmp_ientry->wd; + + /* match the ref from fsnotify_init_markentry() */ + fsnotify_put_mark(&tmp_ientry->fsn_entry); + + /* if this mark added a new event update the group mask */ + if (mask & ~group->mask) + fsnotify_recalc_group_mask(group); + +out_err: + if (ret < 0) + kmem_cache_free(inotify_inode_mark_cachep, tmp_ientry); + + return ret; +} + +static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg) +{ + int ret = 0; + +retry: + /* try to update and existing watch with the new arg */ + ret = inotify_update_existing_watch(group, inode, arg); + /* no mark present, try to add a new one */ + if (ret == -ENOENT) + ret = inotify_new_watch(group, inode, arg); + /* + * inotify_new_watch could race with another thread which did an + * inotify_new_watch between the update_existing and the add watch + * here, go back and try to update an existing mark again. + */ + if (ret == -EEXIST) + goto retry; + + return ret; +} + +static struct fsnotify_group *inotify_new_group(struct user_struct *user, unsigned int max_events) +{ + struct fsnotify_group *group; + unsigned int grp_num; + + /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */ + grp_num = (INOTIFY_GROUP_NUM - atomic_inc_return(&inotify_grp_num)); + group = fsnotify_obtain_group(grp_num, 0, &inotify_fsnotify_ops); + if (IS_ERR(group)) + return group; + + group->max_events = max_events; + + spin_lock_init(&group->inotify_data.idr_lock); + idr_init(&group->inotify_data.idr); + group->inotify_data.last_wd = 0; + group->inotify_data.user = user; + group->inotify_data.fa = NULL; + + return group; +} + + +/* inotify syscalls */ +SYSCALL_DEFINE1(inotify_init1, int, flags) +{ + struct fsnotify_group *group; + struct user_struct *user; + struct file *filp; + struct path path; + 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; + + user = get_current_user(); + if (unlikely(atomic_read(&user->inotify_devs) >= + inotify_max_user_instances)) { + ret = -EMFILE; + goto out_free_uid; + } + + /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */ + group = inotify_new_group(user, inotify_max_queued_events); + if (IS_ERR(group)) { + ret = PTR_ERR(group); + goto out_free_uid; + } + + atomic_inc(&user->inotify_devs); + + path.mnt = inotify_mnt; + path.dentry = inotify_mnt->mnt_root; + path_get(&path); + filp = alloc_file(&path, FMODE_READ, &inotify_fops); + if (!filp) + goto Enfile; + + filp->f_flags = O_RDONLY | (flags & O_NONBLOCK); + filp->private_data = group; + + fd_install(fd, filp); + + return fd; + +Enfile: + ret = -ENFILE; + path_put(&path); + atomic_dec(&user->inotify_devs); +out_free_uid: + free_uid(user); + 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 fsnotify_group *group; + struct inode *inode; + 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 = inotify_find_inode(pathname, &path, flags); + if (ret) + goto fput_and_out; + + /* inode held in place by reference to path; group by fget on fd */ + inode = path.dentry->d_inode; + group = filp->private_data; + + /* create/update an inode mark */ + ret = inotify_update_watch(group, inode, mask); + path_put(&path); +fput_and_out: + fput_light(filp, fput_needed); + return ret; +} + +SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd) +{ + struct fsnotify_group *group; + struct fsnotify_mark_entry *entry; + struct file *filp; + int ret = 0, 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; + } + + group = filp->private_data; + + spin_lock(&group->inotify_data.idr_lock); + entry = idr_find(&group->inotify_data.idr, wd); + if (unlikely(!entry)) { + spin_unlock(&group->inotify_data.idr_lock); + ret = -EINVAL; + goto out; + } + fsnotify_get_mark(entry); + spin_unlock(&group->inotify_data.idr_lock); + + fsnotify_destroy_mark_by_entry(entry); + fsnotify_put_mark(entry); + +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_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark_entry, SLAB_PANIC); + event_priv_cachep = KMEM_CACHE(inotify_event_private_data, SLAB_PANIC); + + inotify_max_queued_events = 16384; + inotify_max_user_instances = 128; + inotify_max_user_watches = 8192; + + return 0; +} +module_init(inotify_user_setup); diff --git a/fs/notify/notification.c b/fs/notify/notification.c new file mode 100644 index 00000000000..b8bf53b4c10 --- /dev/null +++ b/fs/notify/notification.c @@ -0,0 +1,421 @@ +/* + * 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. + */ + +/* + * Basic idea behind the notification queue: An fsnotify group (like inotify) + * sends the userspace notification about events asyncronously some time after + * the event happened. When inotify gets an event it will need to add that + * event to the group notify queue. Since a single event might need to be on + * multiple group's notification queues we can't add the event directly to each + * queue and instead add a small "event_holder" to each queue. This event_holder + * has a pointer back to the original event. Since the majority of events are + * going to end up on one, and only one, notification queue we embed one + * event_holder into each event. This means we have a single allocation instead + * of always needing two. If the embedded event_holder is already in use by + * another group a new event_holder (from fsnotify_event_holder_cachep) will be + * allocated and used. + */ + +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/module.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; +static struct kmem_cache *fsnotify_event_holder_cachep; +/* + * This is a magic event we send when the q is too full. Since it doesn't + * hold real event information we just keep one system wide and use it any time + * it is needed. It's refcnt is set 1 at kernel init time and will never + * get set to 0 so it will never get 'freed' + */ +static struct fsnotify_event q_overflow_event; +static atomic_t fsnotify_sync_cookie = ATOMIC_INIT(0); + +/** + * fsnotify_get_cookie - return a unique cookie for use in synchronizing events. + * Called from fsnotify_move, which is inlined into filesystem modules. + */ +u32 fsnotify_get_cookie(void) +{ + return atomic_inc_return(&fsnotify_sync_cookie); +} +EXPORT_SYMBOL_GPL(fsnotify_get_cookie); + +/* return true if the notify queue is empty, false otherwise */ +bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group) +{ + BUG_ON(!mutex_is_locked(&group->notification_mutex)); + return list_empty(&group->notification_list) ? true : false; +} + +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); + + BUG_ON(!list_empty(&event->private_data_list)); + + kfree(event->file_name); + kmem_cache_free(fsnotify_event_cachep, event); + } +} + +struct fsnotify_event_holder *fsnotify_alloc_event_holder(void) +{ + return kmem_cache_alloc(fsnotify_event_holder_cachep, GFP_KERNEL); +} + +void fsnotify_destroy_event_holder(struct fsnotify_event_holder *holder) +{ + kmem_cache_free(fsnotify_event_holder_cachep, holder); +} + +/* + * Find the private data that the group previously attached to this event when + * the group added the event to the notification queue (fsnotify_add_notify_event) + */ +struct fsnotify_event_private_data *fsnotify_remove_priv_from_event(struct fsnotify_group *group, struct fsnotify_event *event) +{ + struct fsnotify_event_private_data *lpriv; + struct fsnotify_event_private_data *priv = NULL; + + assert_spin_locked(&event->lock); + + list_for_each_entry(lpriv, &event->private_data_list, event_list) { + if (lpriv->group == group) { + priv = lpriv; + list_del(&priv->event_list); + break; + } + } + return priv; +} + +/* + * Check if 2 events contain the same information. We do not compare private data + * but at this moment that isn't a problem for any know fsnotify listeners. + */ +static bool event_compare(struct fsnotify_event *old, struct fsnotify_event *new) +{ + if ((old->mask == new->mask) && + (old->to_tell == new->to_tell) && + (old->data_type == new->data_type) && + (old->name_len == new->name_len)) { + switch (old->data_type) { + case (FSNOTIFY_EVENT_INODE): + /* remember, after old was put on the wait_q we aren't + * allowed to look at the inode any more, only thing + * left to check was if the file_name is the same */ + if (!old->name_len || + !strcmp(old->file_name, new->file_name)) + return true; + break; + case (FSNOTIFY_EVENT_PATH): + if ((old->path.mnt == new->path.mnt) && + (old->path.dentry == new->path.dentry)) + return true; + break; + case (FSNOTIFY_EVENT_NONE): + if (old->mask & FS_Q_OVERFLOW) + return true; + else if (old->mask & FS_IN_IGNORED) + return false; + return false; + }; + } + return false; +} + +/* + * Add an event to the group notification queue. The group can later pull this + * event off the queue to deal with. If the event is successfully added to the + * group's notification queue, a reference is taken on event. + */ +int fsnotify_add_notify_event(struct fsnotify_group *group, struct fsnotify_event *event, + struct fsnotify_event_private_data *priv) +{ + struct fsnotify_event_holder *holder = NULL; + struct list_head *list = &group->notification_list; + struct fsnotify_event_holder *last_holder; + struct fsnotify_event *last_event; + int ret = 0; + + /* + * There is one fsnotify_event_holder embedded inside each fsnotify_event. + * Check if we expect to be able to use that holder. If not alloc a new + * holder. + * For the overflow event it's possible that something will use the in + * event holder before we get the lock so we may need to jump back and + * alloc a new holder, this can't happen for most events... + */ + if (!list_empty(&event->holder.event_list)) { +alloc_holder: + holder = fsnotify_alloc_event_holder(); + if (!holder) + return -ENOMEM; + } + + mutex_lock(&group->notification_mutex); + + if (group->q_len >= group->max_events) { + event = &q_overflow_event; + ret = -EOVERFLOW; + /* sorry, no private data on the overflow event */ + priv = NULL; + } + + spin_lock(&event->lock); + + if (list_empty(&event->holder.event_list)) { + if (unlikely(holder)) + fsnotify_destroy_event_holder(holder); + holder = &event->holder; + } else if (unlikely(!holder)) { + /* between the time we checked above and got the lock the in + * event holder was used, go back and get a new one */ + spin_unlock(&event->lock); + mutex_unlock(&group->notification_mutex); + goto alloc_holder; + } + + if (!list_empty(list)) { + last_holder = list_entry(list->prev, struct fsnotify_event_holder, event_list); + last_event = last_holder->event; + if (event_compare(last_event, event)) { + spin_unlock(&event->lock); + mutex_unlock(&group->notification_mutex); + if (holder != &event->holder) + fsnotify_destroy_event_holder(holder); + return -EEXIST; + } + } + + group->q_len++; + holder->event = event; + + fsnotify_get_event(event); + list_add_tail(&holder->event_list, list); + if (priv) + list_add_tail(&priv->event_list, &event->private_data_list); + spin_unlock(&event->lock); + mutex_unlock(&group->notification_mutex); + + wake_up(&group->notification_waitq); + return ret; +} + +/* + * Remove and return the first event from the notification list. There is a + * reference held on this event since it was on the list. It is the responsibility + * of the caller to drop this reference. + */ +struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group) +{ + struct fsnotify_event *event; + struct fsnotify_event_holder *holder; + + BUG_ON(!mutex_is_locked(&group->notification_mutex)); + + holder = list_first_entry(&group->notification_list, struct fsnotify_event_holder, event_list); + + event = holder->event; + + spin_lock(&event->lock); + holder->event = NULL; + list_del_init(&holder->event_list); + spin_unlock(&event->lock); + + /* event == holder means we are referenced through the in event holder */ + if (holder != &event->holder) + fsnotify_destroy_event_holder(holder); + + group->q_len--; + + return event; +} + +/* + * This will not remove the event, that must be done with fsnotify_remove_notify_event() + */ +struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group) +{ + struct fsnotify_event *event; + struct fsnotify_event_holder *holder; + + BUG_ON(!mutex_is_locked(&group->notification_mutex)); + + holder = list_first_entry(&group->notification_list, struct fsnotify_event_holder, event_list); + event = holder->event; + + return event; +} + +/* + * Called when a group is being torn down to clean up any outstanding + * event notifications. + */ +void fsnotify_flush_notify(struct fsnotify_group *group) +{ + struct fsnotify_event *event; + struct fsnotify_event_private_data *priv; + + mutex_lock(&group->notification_mutex); + while (!fsnotify_notify_queue_is_empty(group)) { + event = fsnotify_remove_notify_event(group); + /* if they don't implement free_event_priv they better not have attached any */ + if (group->ops->free_event_priv) { + spin_lock(&event->lock); + priv = fsnotify_remove_priv_from_event(group, event); + spin_unlock(&event->lock); + if (priv) + group->ops->free_event_priv(priv); + } + fsnotify_put_event(event); /* matches fsnotify_add_notify_event */ + } + mutex_unlock(&group->notification_mutex); +} + +static void initialize_event(struct fsnotify_event *event) +{ + event->holder.event = NULL; + INIT_LIST_HEAD(&event->holder.event_list); + atomic_set(&event->refcnt, 1); + + spin_lock_init(&event->lock); + + event->path.dentry = NULL; + event->path.mnt = NULL; + event->inode = NULL; + event->data_type = FSNOTIFY_EVENT_NONE; + + INIT_LIST_HEAD(&event->private_data_list); + + event->to_tell = NULL; + + event->file_name = NULL; + event->name_len = 0; + + event->sync_cookie = 0; +} + +/* + * fsnotify_create_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. + * + * @to_tell the inode which is supposed to receive the event (sometimes a + * parent of the inode to which the event happened. + * @mask what actually happened. + * @data pointer to the object which was actually affected + * @data_type flag indication if the data is a file, path, inode, nothing... + * @name the filename, if available + */ +struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask, void *data, + int data_type, const char *name, u32 cookie, + gfp_t gfp) +{ + struct fsnotify_event *event; + + event = kmem_cache_alloc(fsnotify_event_cachep, gfp); + if (!event) + return NULL; + + initialize_event(event); + + if (name) { + event->file_name = kstrdup(name, gfp); + if (!event->file_name) { + kmem_cache_free(fsnotify_event_cachep, event); + return NULL; + } + event->name_len = strlen(event->file_name); + } + + event->sync_cookie = cookie; + 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); + fsnotify_event_holder_cachep = KMEM_CACHE(fsnotify_event_holder, SLAB_PANIC); + + initialize_event(&q_overflow_event); + q_overflow_event.mask = FS_Q_OVERFLOW; + + return 0; +} +subsys_initcall(fsnotify_notification_init); + |