FreeBSD/Linux Kernel Cross Reference
sys/fs/dnotify.c
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/sched.h>
18 #include <linux/dnotify.h>
19 #include <linux/init.h>
20 #include <linux/spinlock.h>
21 #include <linux/slab.h>
22
23 extern void send_sigio(struct fown_struct *fown, int fd, int band);
24
25 int dir_notify_enable = 1;
26
27 static rwlock_t dn_lock = RW_LOCK_UNLOCKED;
28 static kmem_cache_t *dn_cache;
29
30 static void redo_inode_mask(struct inode *inode)
31 {
32 unsigned long new_mask;
33 struct dnotify_struct *dn;
34
35 new_mask = 0;
36 for (dn = inode->i_dnotify; dn != NULL; dn = dn->dn_next)
37 new_mask |= dn->dn_mask & ~DN_MULTISHOT;
38 inode->i_dnotify_mask = new_mask;
39 }
40
41 void dnotify_flush(struct file *filp, fl_owner_t id)
42 {
43 struct dnotify_struct *dn;
44 struct dnotify_struct **prev;
45 struct inode *inode;
46
47 inode = filp->f_dentry->d_inode;
48 if (!S_ISDIR(inode->i_mode))
49 return;
50 write_lock(&dn_lock);
51 prev = &inode->i_dnotify;
52 while ((dn = *prev) != NULL) {
53 if ((dn->dn_owner == id) && (dn->dn_filp == filp)) {
54 *prev = dn->dn_next;
55 redo_inode_mask(inode);
56 kmem_cache_free(dn_cache, dn);
57 break;
58 }
59 prev = &dn->dn_next;
60 }
61 write_unlock(&dn_lock);
62 }
63
64 int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
65 {
66 struct dnotify_struct *dn;
67 struct dnotify_struct *odn;
68 struct dnotify_struct **prev;
69 struct inode *inode;
70 fl_owner_t id = current->files;
71
72 if ((arg & ~DN_MULTISHOT) == 0) {
73 dnotify_flush(filp, id);
74 return 0;
75 }
76 if (!dir_notify_enable)
77 return -EINVAL;
78 inode = filp->f_dentry->d_inode;
79 if (!S_ISDIR(inode->i_mode))
80 return -ENOTDIR;
81 dn = kmem_cache_alloc(dn_cache, SLAB_KERNEL);
82 if (dn == NULL)
83 return -ENOMEM;
84 write_lock(&dn_lock);
85 prev = &inode->i_dnotify;
86 while ((odn = *prev) != NULL) {
87 if ((odn->dn_owner == id) && (odn->dn_filp == filp)) {
88 odn->dn_fd = fd;
89 odn->dn_mask |= arg;
90 inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
91 kmem_cache_free(dn_cache, dn);
92 goto out;
93 }
94 prev = &odn->dn_next;
95 }
96 filp->f_owner.pid = current->pid;
97 filp->f_owner.uid = current->uid;
98 filp->f_owner.euid = current->euid;
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 out:
107 write_unlock(&dn_lock);
108 return 0;
109 }
110
111 void __inode_dir_notify(struct inode *inode, unsigned long event)
112 {
113 struct dnotify_struct * dn;
114 struct dnotify_struct **prev;
115 struct fown_struct * fown;
116 int changed = 0;
117
118 write_lock(&dn_lock);
119 prev = &inode->i_dnotify;
120 while ((dn = *prev) != NULL) {
121 if ((dn->dn_mask & event) == 0) {
122 prev = &dn->dn_next;
123 continue;
124 }
125 fown = &dn->dn_filp->f_owner;
126 if (fown->pid)
127 send_sigio(fown, dn->dn_fd, POLL_MSG);
128 if (dn->dn_mask & DN_MULTISHOT)
129 prev = &dn->dn_next;
130 else {
131 *prev = dn->dn_next;
132 changed = 1;
133 kmem_cache_free(dn_cache, dn);
134 }
135 }
136 if (changed)
137 redo_inode_mask(inode);
138 write_unlock(&dn_lock);
139 }
140
141 static int __init dnotify_init(void)
142 {
143 dn_cache = kmem_cache_create("dnotify_cache",
144 sizeof(struct dnotify_struct), 0, 0, NULL, NULL);
145 if (!dn_cache)
146 panic("cannot create dnotify slab cache");
147 return 0;
148 }
149
150 module_init(dnotify_init)
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