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Miklos Szeredibafa9652006-06-25 05:48:51 -07001/*
2 FUSE: Filesystem in Userspace
3 Copyright (C) 2001-2006 Miklos Szeredi <miklos@szeredi.hu>
4
5 This program can be distributed under the terms of the GNU GPL.
6 See the file COPYING.
7*/
8
9#include "fuse_i.h"
10
11#include <linux/init.h>
12#include <linux/module.h>
13
14#define FUSE_CTL_SUPER_MAGIC 0x65735543
15
16/*
17 * This is non-NULL when the single instance of the control filesystem
18 * exists. Protected by fuse_mutex
19 */
20static struct super_block *fuse_control_sb;
21
22static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
23{
24 struct fuse_conn *fc;
25 mutex_lock(&fuse_mutex);
Josef Sipek7706a9d2006-12-08 02:37:02 -080026 fc = file->f_path.dentry->d_inode->i_private;
Miklos Szeredibafa9652006-06-25 05:48:51 -070027 if (fc)
28 fc = fuse_conn_get(fc);
29 mutex_unlock(&fuse_mutex);
30 return fc;
31}
32
33static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf,
34 size_t count, loff_t *ppos)
35{
36 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
37 if (fc) {
38 fuse_abort_conn(fc);
39 fuse_conn_put(fc);
40 }
41 return count;
42}
43
44static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf,
45 size_t len, loff_t *ppos)
46{
47 char tmp[32];
48 size_t size;
49
50 if (!*ppos) {
51 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
52 if (!fc)
53 return 0;
54
55 file->private_data=(void *)(long)atomic_read(&fc->num_waiting);
56 fuse_conn_put(fc);
57 }
58 size = sprintf(tmp, "%ld\n", (long)file->private_data);
59 return simple_read_from_buffer(buf, len, ppos, tmp, size);
60}
61
62static const struct file_operations fuse_ctl_abort_ops = {
63 .open = nonseekable_open,
64 .write = fuse_conn_abort_write,
65};
66
67static const struct file_operations fuse_ctl_waiting_ops = {
68 .open = nonseekable_open,
69 .read = fuse_conn_waiting_read,
70};
71
72static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
73 struct fuse_conn *fc,
74 const char *name,
75 int mode, int nlink,
Arjan van de Ven754661f2007-02-12 00:55:38 -080076 const struct inode_operations *iop,
Miklos Szeredibafa9652006-06-25 05:48:51 -070077 const struct file_operations *fop)
78{
79 struct dentry *dentry;
80 struct inode *inode;
81
82 BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
83 dentry = d_alloc_name(parent, name);
84 if (!dentry)
85 return NULL;
86
87 fc->ctl_dentry[fc->ctl_ndents++] = dentry;
88 inode = new_inode(fuse_control_sb);
89 if (!inode)
90 return NULL;
91
92 inode->i_mode = mode;
93 inode->i_uid = fc->user_id;
94 inode->i_gid = fc->group_id;
95 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
96 /* setting ->i_op to NULL is not allowed */
97 if (iop)
98 inode->i_op = iop;
99 inode->i_fop = fop;
100 inode->i_nlink = nlink;
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700101 inode->i_private = fc;
Miklos Szeredibafa9652006-06-25 05:48:51 -0700102 d_add(dentry, inode);
103 return dentry;
104}
105
106/*
107 * Add a connection to the control filesystem (if it exists). Caller
Miklos Szeredi873302c2006-07-30 03:04:10 -0700108 * must hold fuse_mutex
Miklos Szeredibafa9652006-06-25 05:48:51 -0700109 */
110int fuse_ctl_add_conn(struct fuse_conn *fc)
111{
112 struct dentry *parent;
113 char name[32];
114
115 if (!fuse_control_sb)
116 return 0;
117
118 parent = fuse_control_sb->s_root;
Dave Hansend8c76e62006-09-30 23:29:04 -0700119 inc_nlink(parent->d_inode);
Miklos Szeredib6f2fcb2008-04-30 00:54:34 -0700120 sprintf(name, "%u", fc->dev);
Miklos Szeredibafa9652006-06-25 05:48:51 -0700121 parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
122 &simple_dir_inode_operations,
123 &simple_dir_operations);
124 if (!parent)
125 goto err;
126
127 if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
128 NULL, &fuse_ctl_waiting_ops) ||
129 !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
130 NULL, &fuse_ctl_abort_ops))
131 goto err;
132
133 return 0;
134
135 err:
136 fuse_ctl_remove_conn(fc);
137 return -ENOMEM;
138}
139
140/*
141 * Remove a connection from the control filesystem (if it exists).
Miklos Szeredi873302c2006-07-30 03:04:10 -0700142 * Caller must hold fuse_mutex
Miklos Szeredibafa9652006-06-25 05:48:51 -0700143 */
144void fuse_ctl_remove_conn(struct fuse_conn *fc)
145{
146 int i;
147
148 if (!fuse_control_sb)
149 return;
150
151 for (i = fc->ctl_ndents - 1; i >= 0; i--) {
152 struct dentry *dentry = fc->ctl_dentry[i];
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700153 dentry->d_inode->i_private = NULL;
Miklos Szeredibafa9652006-06-25 05:48:51 -0700154 d_drop(dentry);
155 dput(dentry);
156 }
157 fuse_control_sb->s_root->d_inode->i_nlink--;
158}
159
160static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
161{
162 struct tree_descr empty_descr = {""};
163 struct fuse_conn *fc;
164 int err;
165
166 err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
167 if (err)
168 return err;
169
170 mutex_lock(&fuse_mutex);
171 BUG_ON(fuse_control_sb);
172 fuse_control_sb = sb;
173 list_for_each_entry(fc, &fuse_conn_list, entry) {
174 err = fuse_ctl_add_conn(fc);
175 if (err) {
176 fuse_control_sb = NULL;
177 mutex_unlock(&fuse_mutex);
178 return err;
179 }
180 }
181 mutex_unlock(&fuse_mutex);
182
183 return 0;
184}
185
186static int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags,
187 const char *dev_name, void *raw_data,
188 struct vfsmount *mnt)
189{
190 return get_sb_single(fs_type, flags, raw_data,
191 fuse_ctl_fill_super, mnt);
192}
193
194static void fuse_ctl_kill_sb(struct super_block *sb)
195{
Miklos Szerediff795442007-01-29 13:19:54 -0800196 struct fuse_conn *fc;
197
Miklos Szeredibafa9652006-06-25 05:48:51 -0700198 mutex_lock(&fuse_mutex);
199 fuse_control_sb = NULL;
Miklos Szerediff795442007-01-29 13:19:54 -0800200 list_for_each_entry(fc, &fuse_conn_list, entry)
201 fc->ctl_ndents = 0;
Miklos Szeredibafa9652006-06-25 05:48:51 -0700202 mutex_unlock(&fuse_mutex);
203
204 kill_litter_super(sb);
205}
206
207static struct file_system_type fuse_ctl_fs_type = {
208 .owner = THIS_MODULE,
209 .name = "fusectl",
210 .get_sb = fuse_ctl_get_sb,
211 .kill_sb = fuse_ctl_kill_sb,
212};
213
214int __init fuse_ctl_init(void)
215{
216 return register_filesystem(&fuse_ctl_fs_type);
217}
218
219void fuse_ctl_cleanup(void)
220{
221 unregister_filesystem(&fuse_ctl_fs_type);
222}