Subversion Repositories test_project

/*

 * 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)