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/*
* Directory notifications for Linux.
*
* Copyright (C) 2000,2001,2002 Stephen Rothwell
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/dnotify.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
int dir_notify_enable __read_mostly = 1;
static struct kmem_cache *dn_cache __read_mostly;
static void redo_inode_mask(struct inode *inode)
{
unsigned long new_mask;
struct dnotify_struct *dn;
new_mask = 0;
for (dn = inode->i_dnotify; dn != NULL; dn = dn->dn_next)
new_mask |= dn->dn_mask & ~DN_MULTISHOT;
inode->i_dnotify_mask = new_mask;
}
void dnotify_flush(struct file *filp, fl_owner_t id)
{
struct dnotify_struct *dn;
struct dnotify_struct **prev;
struct inode *inode;
inode = filp->f_path.dentry->d_inode;
if (!S_ISDIR(inode->i_mode))
return;
spin_lock(&inode->i_lock);
prev = &inode->i_dnotify;
while ((dn = *prev) != NULL) {
if ((dn->dn_owner == id) && (dn->dn_filp == filp)) {
*prev = dn->dn_next;
redo_inode_mask(inode);
kmem_cache_free(dn_cache, dn);
break;
}
prev = &dn->dn_next;
}
spin_unlock(&inode->i_lock);
}
int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
{
struct dnotify_struct *dn;
struct dnotify_struct *odn;
struct dnotify_struct **prev;
struct inode *inode;
fl_owner_t id = current->files;
int error = 0;
if ((arg & ~DN_MULTISHOT) == 0) {
dnotify_flush(filp, id);
return 0;
}
if (!dir_notify_enable)
return -EINVAL;
inode = filp->f_path.dentry->d_inode;
if (!S_ISDIR(inode->i_mode))
return -ENOTDIR;
dn = kmem_cache_alloc(dn_cache, GFP_KERNEL);
if (dn == NULL)
return -ENOMEM;
spin_lock(&inode->i_lock);
prev = &inode->i_dnotify;
while ((odn = *prev) != NULL) {
if ((odn->dn_owner == id) && (odn->dn_filp == filp)) {
odn->dn_fd = fd;
odn->dn_mask |= arg;
inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
goto out_free;
}
prev = &odn->dn_next;
}
error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
if (error)
goto out_free;
dn->dn_mask = arg;
dn->dn_fd = fd;
dn->dn_filp = filp;
dn->dn_owner = id;
inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
dn->dn_next = inode->i_dnotify;
inode->i_dnotify = dn;
spin_unlock(&inode->i_lock);
if (filp->f_op && filp->f_op->dir_notify)
return filp->f_op->dir_notify(filp, arg);
return 0;
out_free:
spin_unlock(&inode->i_lock);
kmem_cache_free(dn_cache, dn);
return error;
}
void __inode_dir_notify(struct inode *inode, unsigned long event)
{
struct dnotify_struct * dn;
struct dnotify_struct **prev;
struct fown_struct * fown;
int changed = 0;
spin_lock(&inode->i_lock);
prev = &inode->i_dnotify;
while ((dn = *prev) != NULL) {
if ((dn->dn_mask & event) == 0) {
prev = &dn->dn_next;
continue;
}
fown = &dn->dn_filp->f_owner;
send_sigio(fown, dn->dn_fd, POLL_MSG);
if (dn->dn_mask & DN_MULTISHOT)
prev = &dn->dn_next;
else {
*prev = dn->dn_next;
changed = 1;
kmem_cache_free(dn_cache, dn);
}
}
if (changed)
redo_inode_mask(inode);
spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(__inode_dir_notify);
/*
* This is hopelessly wrong, but unfixable without API changes. At
* least it doesn't oops the kernel...
*
* To safely access ->d_parent we need to keep d_move away from it. Use the
* dentry's d_lock for this.
*/
void dnotify_parent(struct dentry *dentry, unsigned long event)
{
struct dentry *parent;
if (!dir_notify_enable)
return;
spin_lock(&dentry->d_lock);
parent = dentry->d_parent;
if (parent->d_inode->i_dnotify_mask & event) {
dget(parent);
spin_unlock(&dentry->d_lock);
__inode_dir_notify(parent->d_inode, event);
dput(parent);
} else {
spin_unlock(&dentry->d_lock);
}
}
EXPORT_SYMBOL_GPL(dnotify_parent);
static int __init dnotify_init(void)
{
dn_cache = kmem_cache_create("dnotify_cache",
sizeof(struct dnotify_struct), 0, SLAB_PANIC, NULL);
return 0;
}
module_init(dnotify_init)
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