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Miklos Szeredibafa9652006-06-25 05:48:51 -07001/*
2 FUSE: Filesystem in Userspace
Miklos Szeredi1729a162008-11-26 12:03:54 +01003 Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu>
Miklos Szeredibafa9652006-06-25 05:48:51 -07004
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) {
Miklos Szeredi1729a162008-11-26 12:03:54 +010051 long value;
Miklos Szeredibafa9652006-06-25 05:48:51 -070052 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
53 if (!fc)
54 return 0;
55
Miklos Szeredi1729a162008-11-26 12:03:54 +010056 value = atomic_read(&fc->num_waiting);
57 file->private_data = (void *)value;
Miklos Szeredibafa9652006-06-25 05:48:51 -070058 fuse_conn_put(fc);
59 }
60 size = sprintf(tmp, "%ld\n", (long)file->private_data);
61 return simple_read_from_buffer(buf, len, ppos, tmp, size);
62}
63
64static const struct file_operations fuse_ctl_abort_ops = {
65 .open = nonseekable_open,
66 .write = fuse_conn_abort_write,
67};
68
69static const struct file_operations fuse_ctl_waiting_ops = {
70 .open = nonseekable_open,
71 .read = fuse_conn_waiting_read,
72};
73
74static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
75 struct fuse_conn *fc,
76 const char *name,
77 int mode, int nlink,
Arjan van de Ven754661f2007-02-12 00:55:38 -080078 const struct inode_operations *iop,
Miklos Szeredibafa9652006-06-25 05:48:51 -070079 const struct file_operations *fop)
80{
81 struct dentry *dentry;
82 struct inode *inode;
83
84 BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
85 dentry = d_alloc_name(parent, name);
86 if (!dentry)
87 return NULL;
88
89 fc->ctl_dentry[fc->ctl_ndents++] = dentry;
90 inode = new_inode(fuse_control_sb);
91 if (!inode)
92 return NULL;
93
94 inode->i_mode = mode;
95 inode->i_uid = fc->user_id;
96 inode->i_gid = fc->group_id;
97 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
98 /* setting ->i_op to NULL is not allowed */
99 if (iop)
100 inode->i_op = iop;
101 inode->i_fop = fop;
102 inode->i_nlink = nlink;
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700103 inode->i_private = fc;
Miklos Szeredibafa9652006-06-25 05:48:51 -0700104 d_add(dentry, inode);
105 return dentry;
106}
107
108/*
109 * Add a connection to the control filesystem (if it exists). Caller
Miklos Szeredi873302c2006-07-30 03:04:10 -0700110 * must hold fuse_mutex
Miklos Szeredibafa9652006-06-25 05:48:51 -0700111 */
112int fuse_ctl_add_conn(struct fuse_conn *fc)
113{
114 struct dentry *parent;
115 char name[32];
116
117 if (!fuse_control_sb)
118 return 0;
119
120 parent = fuse_control_sb->s_root;
Dave Hansend8c76e62006-09-30 23:29:04 -0700121 inc_nlink(parent->d_inode);
Miklos Szeredib6f2fcb2008-04-30 00:54:34 -0700122 sprintf(name, "%u", fc->dev);
Miklos Szeredibafa9652006-06-25 05:48:51 -0700123 parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
124 &simple_dir_inode_operations,
125 &simple_dir_operations);
126 if (!parent)
127 goto err;
128
129 if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
130 NULL, &fuse_ctl_waiting_ops) ||
131 !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
132 NULL, &fuse_ctl_abort_ops))
133 goto err;
134
135 return 0;
136
137 err:
138 fuse_ctl_remove_conn(fc);
139 return -ENOMEM;
140}
141
142/*
143 * Remove a connection from the control filesystem (if it exists).
Miklos Szeredi873302c2006-07-30 03:04:10 -0700144 * Caller must hold fuse_mutex
Miklos Szeredibafa9652006-06-25 05:48:51 -0700145 */
146void fuse_ctl_remove_conn(struct fuse_conn *fc)
147{
148 int i;
149
150 if (!fuse_control_sb)
151 return;
152
153 for (i = fc->ctl_ndents - 1; i >= 0; i--) {
154 struct dentry *dentry = fc->ctl_dentry[i];
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700155 dentry->d_inode->i_private = NULL;
Miklos Szeredibafa9652006-06-25 05:48:51 -0700156 d_drop(dentry);
157 dput(dentry);
158 }
159 fuse_control_sb->s_root->d_inode->i_nlink--;
160}
161
162static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
163{
164 struct tree_descr empty_descr = {""};
165 struct fuse_conn *fc;
166 int err;
167
168 err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
169 if (err)
170 return err;
171
172 mutex_lock(&fuse_mutex);
173 BUG_ON(fuse_control_sb);
174 fuse_control_sb = sb;
175 list_for_each_entry(fc, &fuse_conn_list, entry) {
176 err = fuse_ctl_add_conn(fc);
177 if (err) {
178 fuse_control_sb = NULL;
179 mutex_unlock(&fuse_mutex);
180 return err;
181 }
182 }
183 mutex_unlock(&fuse_mutex);
184
185 return 0;
186}
187
188static int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags,
189 const char *dev_name, void *raw_data,
190 struct vfsmount *mnt)
191{
192 return get_sb_single(fs_type, flags, raw_data,
193 fuse_ctl_fill_super, mnt);
194}
195
196static void fuse_ctl_kill_sb(struct super_block *sb)
197{
Miklos Szerediff795442007-01-29 13:19:54 -0800198 struct fuse_conn *fc;
199
Miklos Szeredibafa9652006-06-25 05:48:51 -0700200 mutex_lock(&fuse_mutex);
201 fuse_control_sb = NULL;
Miklos Szerediff795442007-01-29 13:19:54 -0800202 list_for_each_entry(fc, &fuse_conn_list, entry)
203 fc->ctl_ndents = 0;
Miklos Szeredibafa9652006-06-25 05:48:51 -0700204 mutex_unlock(&fuse_mutex);
205
206 kill_litter_super(sb);
207}
208
209static struct file_system_type fuse_ctl_fs_type = {
210 .owner = THIS_MODULE,
211 .name = "fusectl",
212 .get_sb = fuse_ctl_get_sb,
213 .kill_sb = fuse_ctl_kill_sb,
214};
215
216int __init fuse_ctl_init(void)
217{
218 return register_filesystem(&fuse_ctl_fs_type);
219}
220
221void fuse_ctl_cleanup(void)
222{
223 unregister_filesystem(&fuse_ctl_fs_type);
224}