Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/*
2 * Directory notifications for Linux.
3 *
4 * Copyright (C) 2000,2001,2002 Stephen Rothwell
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the
8 * Free Software Foundation; either version 2, or (at your option) any
9 * later version.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * General Public License for more details.
15 */
16#include <linux/fs.h>
17#include <linux/module.h>
18#include <linux/sched.h>
19#include <linux/dnotify.h>
20#include <linux/init.h>
21#include <linux/spinlock.h>
22#include <linux/slab.h>
23
24int dir_notify_enable __read_mostly = 1;
25
26static struct kmem_cache *dn_cache __read_mostly;
27
28static void redo_inode_mask(struct inode *inode)
29{
30 unsigned long new_mask;
31 struct dnotify_struct *dn;
32
33 new_mask = 0;
34 for (dn = inode->i_dnotify; dn != NULL; dn = dn->dn_next)
35 new_mask |= dn->dn_mask & ~DN_MULTISHOT;
36 inode->i_dnotify_mask = new_mask;
37}
38
39void dnotify_flush(struct file *filp, fl_owner_t id)
40{
41 struct dnotify_struct *dn;
42 struct dnotify_struct **prev;
43 struct inode *inode;
44
45 inode = filp->f_path.dentry->d_inode;
46 if (!S_ISDIR(inode->i_mode))
47 return;
48 spin_lock(&inode->i_lock);
49 prev = &inode->i_dnotify;
50 while ((dn = *prev) != NULL) {
51 if ((dn->dn_owner == id) && (dn->dn_filp == filp)) {
52 *prev = dn->dn_next;
53 redo_inode_mask(inode);
54 kmem_cache_free(dn_cache, dn);
55 break;
56 }
57 prev = &dn->dn_next;
58 }
59 spin_unlock(&inode->i_lock);
60}
61
62int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
63{
64 struct dnotify_struct *dn;
65 struct dnotify_struct *odn;
66 struct dnotify_struct **prev;
67 struct inode *inode;
68 fl_owner_t id = current->files;
69 int error = 0;
70
71 if ((arg & ~DN_MULTISHOT) == 0) {
72 dnotify_flush(filp, id);
73 return 0;
74 }
75 if (!dir_notify_enable)
76 return -EINVAL;
77 inode = filp->f_path.dentry->d_inode;
78 if (!S_ISDIR(inode->i_mode))
79 return -ENOTDIR;
80 dn = kmem_cache_alloc(dn_cache, GFP_KERNEL);
81 if (dn == NULL)
82 return -ENOMEM;
83 spin_lock(&inode->i_lock);
84 prev = &inode->i_dnotify;
85 while ((odn = *prev) != NULL) {
86 if ((odn->dn_owner == id) && (odn->dn_filp == filp)) {
87 odn->dn_fd = fd;
88 odn->dn_mask |= arg;
89 inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
90 goto out_free;
91 }
92 prev = &odn->dn_next;
93 }
94
95 error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
96 if (error)
97 goto out_free;
98
99 dn->dn_mask = arg;
100 dn->dn_fd = fd;
101 dn->dn_filp = filp;
102 dn->dn_owner = id;
103 inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
104 dn->dn_next = inode->i_dnotify;
105 inode->i_dnotify = dn;
106 spin_unlock(&inode->i_lock);
107
108 if (filp->f_op && filp->f_op->dir_notify)
109 return filp->f_op->dir_notify(filp, arg);
110 return 0;
111
112out_free:
113 spin_unlock(&inode->i_lock);
114 kmem_cache_free(dn_cache, dn);
115 return error;
116}
117
118void __inode_dir_notify(struct inode *inode, unsigned long event)
119{
120 struct dnotify_struct * dn;
121 struct dnotify_struct **prev;
122 struct fown_struct * fown;
123 int changed = 0;
124
125 spin_lock(&inode->i_lock);
126 prev = &inode->i_dnotify;
127 while ((dn = *prev) != NULL) {
128 if ((dn->dn_mask & event) == 0) {
129 prev = &dn->dn_next;
130 continue;
131 }
132 fown = &dn->dn_filp->f_owner;
133 send_sigio(fown, dn->dn_fd, POLL_MSG);
134 if (dn->dn_mask & DN_MULTISHOT)
135 prev = &dn->dn_next;
136 else {
137 *prev = dn->dn_next;
138 changed = 1;
139 kmem_cache_free(dn_cache, dn);
140 }
141 }
142 if (changed)
143 redo_inode_mask(inode);
144 spin_unlock(&inode->i_lock);
145}
146
147EXPORT_SYMBOL(__inode_dir_notify);
148
149/*
150 * This is hopelessly wrong, but unfixable without API changes. At
151 * least it doesn't oops the kernel...
152 *
153 * To safely access ->d_parent we need to keep d_move away from it. Use the
154 * dentry's d_lock for this.
155 */
156void dnotify_parent(struct dentry *dentry, unsigned long event)
157{
158 struct dentry *parent;
159
160 if (!dir_notify_enable)
161 return;
162
163 spin_lock(&dentry->d_lock);
164 parent = dentry->d_parent;
165 if (parent->d_inode->i_dnotify_mask & event) {
166 dget(parent);
167 spin_unlock(&dentry->d_lock);
168 __inode_dir_notify(parent->d_inode, event);
169 dput(parent);
170 } else {
171 spin_unlock(&dentry->d_lock);
172 }
173}
174EXPORT_SYMBOL_GPL(dnotify_parent);
175
176static int __init dnotify_init(void)
177{
178 dn_cache = kmem_cache_create("dnotify_cache",
179 sizeof(struct dnotify_struct), 0, SLAB_PANIC, NULL, NULL);
180 return 0;
181}
182
183module_init(dnotify_init)