Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/fs/dnotify.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 4375 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | |
24 | int dir_notify_enable = 1; |
25 | |
26 | static kmem_cache_t *dn_cache; |
27 | |
28 | static 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 | |
39 | void 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_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 | |
62 | int 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_dentry->d_inode; |
78 | if (!S_ISDIR(inode->i_mode)) |
79 | return -ENOTDIR; |
80 | dn = kmem_cache_alloc(dn_cache, SLAB_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, current->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 | |
112 | out_free: |
113 | spin_unlock(&inode->i_lock); |
114 | kmem_cache_free(dn_cache, dn); |
115 | return error; |
116 | } |
117 | |
118 | void __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 | |
147 | EXPORT_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 | */ |
156 | void 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 | } |
174 | EXPORT_SYMBOL_GPL(dnotify_parent); |
175 | |
176 | static 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 | |
183 | module_init(dnotify_init) |