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/*
* Directory notifications for Linux.
*
* Copyright (C) 2000 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/sched.h>
#include <linux/dnotify.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
extern void send_sigio(struct fown_struct *fown, int fd, int band);
int dir_notify_enable = 1;
static rwlock_t dn_lock = RW_LOCK_UNLOCKED;
static kmem_cache_t *dn_cache;
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;
}
int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
{
struct dnotify_struct *dn = NULL;
struct dnotify_struct *odn;
struct dnotify_struct **prev;
struct inode *inode;
int turning_off = (arg & ~DN_MULTISHOT) == 0;
if (!turning_off && !dir_notify_enable)
return -EINVAL;
inode = filp->f_dentry->d_inode;
if (!S_ISDIR(inode->i_mode))
return -ENOTDIR;
if (!turning_off) {
dn = kmem_cache_alloc(dn_cache, SLAB_KERNEL);
if (dn == NULL)
return -ENOMEM;
}
write_lock(&dn_lock);
prev = &inode->i_dnotify;
for (odn = *prev; odn != NULL; prev = &odn->dn_next, odn = *prev)
if (odn->dn_filp == filp)
break;
if (odn != NULL) {
if (turning_off) {
*prev = odn->dn_next;
redo_inode_mask(inode);
dn = odn;
goto out_free;
}
odn->dn_fd = fd;
odn->dn_mask |= arg;
inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
goto out_free;
}
if (turning_off)
goto out;
filp->f_owner.pid = current->pid;
filp->f_owner.uid = current->uid;
filp->f_owner.euid = current->euid;
dn->dn_magic = DNOTIFY_MAGIC;
dn->dn_mask = arg;
dn->dn_fd = fd;
dn->dn_filp = filp;
inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
dn->dn_next = inode->i_dnotify;
inode->i_dnotify = dn;
out:
write_unlock(&dn_lock);
return 0;
out_free:
kmem_cache_free(dn_cache, dn);
goto out;
}
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;
write_lock(&dn_lock);
prev = &inode->i_dnotify;
while ((dn = *prev) != NULL) {
if (dn->dn_magic != DNOTIFY_MAGIC) {
printk(KERN_ERR "__inode_dir_notify: bad magic "
"number in dnotify_struct!\n");
goto out;
}
if ((dn->dn_mask & event) == 0) {
prev = &dn->dn_next;
continue;
}
fown = &dn->dn_filp->f_owner;
if (fown->pid)
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);
out:
write_unlock(&dn_lock);
}
static int __init dnotify_init(void)
{
dn_cache = kmem_cache_create("dnotify cache",
sizeof(struct dnotify_struct), 0, 0, NULL, NULL);
if (!dn_cache)
panic("cannot create dnotify slab cache");
return 0;
}
module_init(dnotify_init)
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