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1275 |
phoenix |
/*
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* Directory notifications for Linux.
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*
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* Copyright (C) 2000,2001,2002 Stephen Rothwell
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2, or (at your option) any
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* later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/fs.h>
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#include <linux/sched.h>
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#include <linux/dnotify.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <linux/slab.h>
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extern void send_sigio(struct fown_struct *fown, int fd, int band);
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int dir_notify_enable = 1;
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static rwlock_t dn_lock = RW_LOCK_UNLOCKED;
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static kmem_cache_t *dn_cache;
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static void redo_inode_mask(struct inode *inode)
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{
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unsigned long new_mask;
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struct dnotify_struct *dn;
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new_mask = 0;
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for (dn = inode->i_dnotify; dn != NULL; dn = dn->dn_next)
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new_mask |= dn->dn_mask & ~DN_MULTISHOT;
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inode->i_dnotify_mask = new_mask;
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}
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void dnotify_flush(struct file *filp, fl_owner_t id)
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{
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struct dnotify_struct *dn;
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struct dnotify_struct **prev;
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struct inode *inode;
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inode = filp->f_dentry->d_inode;
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if (!S_ISDIR(inode->i_mode))
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return;
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write_lock(&dn_lock);
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prev = &inode->i_dnotify;
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while ((dn = *prev) != NULL) {
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if ((dn->dn_owner == id) && (dn->dn_filp == filp)) {
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*prev = dn->dn_next;
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redo_inode_mask(inode);
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kmem_cache_free(dn_cache, dn);
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break;
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}
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prev = &dn->dn_next;
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}
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write_unlock(&dn_lock);
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}
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int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
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{
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struct dnotify_struct *dn;
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struct dnotify_struct *odn;
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struct dnotify_struct **prev;
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struct inode *inode;
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fl_owner_t id = current->files;
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if ((arg & ~DN_MULTISHOT) == 0) {
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dnotify_flush(filp, id);
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return 0;
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}
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if (!dir_notify_enable)
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return -EINVAL;
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inode = filp->f_dentry->d_inode;
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if (!S_ISDIR(inode->i_mode))
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return -ENOTDIR;
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dn = kmem_cache_alloc(dn_cache, SLAB_KERNEL);
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if (dn == NULL)
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return -ENOMEM;
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write_lock(&dn_lock);
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prev = &inode->i_dnotify;
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while ((odn = *prev) != NULL) {
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if ((odn->dn_owner == id) && (odn->dn_filp == filp)) {
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odn->dn_fd = fd;
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odn->dn_mask |= arg;
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inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
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kmem_cache_free(dn_cache, dn);
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goto out;
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}
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prev = &odn->dn_next;
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}
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filp->f_owner.pid = current->pid;
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filp->f_owner.uid = current->uid;
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filp->f_owner.euid = current->euid;
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dn->dn_mask = arg;
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dn->dn_fd = fd;
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dn->dn_filp = filp;
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dn->dn_owner = id;
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inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
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dn->dn_next = inode->i_dnotify;
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inode->i_dnotify = dn;
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out:
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write_unlock(&dn_lock);
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return 0;
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}
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void __inode_dir_notify(struct inode *inode, unsigned long event)
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{
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struct dnotify_struct * dn;
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struct dnotify_struct **prev;
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struct fown_struct * fown;
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int changed = 0;
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write_lock(&dn_lock);
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prev = &inode->i_dnotify;
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while ((dn = *prev) != NULL) {
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if ((dn->dn_mask & event) == 0) {
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prev = &dn->dn_next;
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continue;
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}
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fown = &dn->dn_filp->f_owner;
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if (fown->pid)
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send_sigio(fown, dn->dn_fd, POLL_MSG);
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if (dn->dn_mask & DN_MULTISHOT)
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prev = &dn->dn_next;
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else {
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*prev = dn->dn_next;
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changed = 1;
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kmem_cache_free(dn_cache, dn);
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}
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}
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if (changed)
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redo_inode_mask(inode);
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write_unlock(&dn_lock);
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}
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static int __init dnotify_init(void)
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{
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dn_cache = kmem_cache_create("dnotify_cache",
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sizeof(struct dnotify_struct), 0, 0, NULL, NULL);
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if (!dn_cache)
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panic("cannot create dnotify slab cache");
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return 0;
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}
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module_init(dnotify_init)
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