/*
* Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/writeback.h> /* for inode_lock */
#include <asm/atomic.h>
#include <linux/fsnotify_backend.h>
#include "fsnotify.h"
/*
* Recalculate the mask of events relevant to a given inode locked.
*/
static void fsnotify_recalc_inode_mask_locked(struct inode *inode)
{
struct fsnotify_mark *mark;
struct hlist_node *pos;
__u32 new_mask = 0;
assert_spin_locked(&inode->i_lock);
hlist_for_each_entry(mark, pos, &inode->i_fsnotify_marks, i.i_list)
new_mask |= mark->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);
}
void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
{
struct inode *inode = mark->i.inode;
assert_spin_locked(&mark->lock);
assert_spin_locked(&mark->group->mark_lock);
spin_lock(&inode->i_lock);
hlist_del_init_rcu(&mark->i.i_list);
mark->i.inode = NULL;
/*
* this mark is now off the inode->i_fsnotify_marks 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);
}
/*
* Given an inode, destroy all of the marks associated with that inode.
*/
void fsnotify_clear_marks_by_inode(struct inode *inode)
{
struct fsnotify_mark *mark, *lmark;
struct hlist_node *pos, *n;
LIST_HEAD(free_list);
spin_lock(&inode->i_lock);
hlist_for_each_entry_safe(mark, pos, n, &inode->i_fsnotify_marks, i.i_list) {
list_add(&mark->i.free_i_list, &free_list);
hlist_del_init_rcu(&mark->i.i_list);
fsnotify_get_mark(mark);
}
spin_unlock(&inode->i_lock);
list_for_each_entry_safe(mark, lmark, &free_list, i.free_i_list) {
fsnotify_destroy_mark(mark);
fsnotify_put_mark(mark);
}
}
/*
* Given a group clear all of the inode marks associated with that group.
*/
void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
{
fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_INODE);
}
/*
* 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 *fsnotify_find_inode_mark_locked(struct fsnotify_group *group,
struct inode *inode)
{
struct fsnotify_mark *mark;
struct hlist_node *pos;
assert_spin_locked(&inode->i_lock);
hlist_for_each_entry(mark, pos, &inode->i_fsnotify_marks, i.i_list) {
if (mark->group == group) {
fsnotify_get_mark(mark);
return mark;
}
}
return NULL;
}
/*
* 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 *fsnotify_find_inode_mark(struct fsnotify_group *group,
struct inode *inode)
{
struct fsnotify_mark *mark;
spin_lock(&inode->i_lock);
mark = fsnotify_find_inode_mark_locked(group, inode);
spin_unlock(&inode->i_lock);
return mark;
}
/*
* If we are setting a mark mask on an inode mark we should pin the inode
* in memory.
*/
void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *mark,
__u32 mask)
{
struct inode *inode;
assert_spin_locked(&mark->lock);
if (mask &&
mark->i.inode &&
!(mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED)) {
mark->flags |= FSNOTIFY_MARK_FLAG_OBJECT_PINNED;
inode = igrab(mark->i.inode);
/*
* we shouldn't be able to get here if the inode wasn't
* already safely held in memory. But bug in case it
* ever is wrong.
*/
BUG_ON(!inode);
}
}
/*
* Attach an initialized mark to a given 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. These
* marks are ordered according to the group's location in memory.
*/
int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
struct fsnotify_group *group, struct inode *inode,
int allow_dups)
{
struct fsnotify_mark *lmark;
struct hlist_node *node, *last = NULL;
int ret = 0;
mark->flags |= FSNOTIFY_MARK_FLAG_INODE;
assert_spin_locked(&mark->lock);
assert_spin_locked(&group->mark_lock);
spin_lock(&inode->i_lock);
mark->i.inode = inode;
/* is mark the first mark? */
if (hlist_empty(&inode->i_fsnotify_marks)) {
hlist_add_head_rcu(&mark->i.i_list, &inode->i_fsnotify_marks);
goto out;
}
/* should mark be in the middle of the current list? */
hlist_for_each_entry(lmark, node, &inode->i_fsnotify_marks, i.i_list) {
last = node;
if ((lmark->group == group) && !allow_dups) {
ret = -EEXIST;
goto out;
}
if (mark->group < lmark->group)
continue;
hlist_add_before_rcu(&mark->i.i_list, &lmark->i.i_list);
goto out;
}
BUG_ON(last == NULL);
/* mark should be the last entry. last is the current last entry */
hlist_add_after_rcu(last, &mark->i.i_list);
out:
fsnotify_recalc_inode_mask_locked(inode);
spin_unlock(&inode->i_lock);
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_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_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_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);
}
}
