Commit | Line | Data |
---|---|---|
bafa9654 MS |
1 | /* |
2 | FUSE: Filesystem in Userspace | |
1729a16c | 3 | Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu> |
bafa9654 MS |
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 | */ | |
20 | static struct super_block *fuse_control_sb; | |
21 | ||
22 | static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file) | |
23 | { | |
24 | struct fuse_conn *fc; | |
25 | mutex_lock(&fuse_mutex); | |
7706a9d6 | 26 | fc = file->f_path.dentry->d_inode->i_private; |
bafa9654 MS |
27 | if (fc) |
28 | fc = fuse_conn_get(fc); | |
29 | mutex_unlock(&fuse_mutex); | |
30 | return fc; | |
31 | } | |
32 | ||
33 | static 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 | ||
44 | static 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) { | |
1729a16c | 51 | long value; |
bafa9654 MS |
52 | struct fuse_conn *fc = fuse_ctl_file_conn_get(file); |
53 | if (!fc) | |
54 | return 0; | |
55 | ||
1729a16c MS |
56 | value = atomic_read(&fc->num_waiting); |
57 | file->private_data = (void *)value; | |
bafa9654 MS |
58 | 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 | ||
79a9d994 CH |
64 | static ssize_t fuse_conn_limit_read(struct file *file, char __user *buf, |
65 | size_t len, loff_t *ppos, unsigned val) | |
66 | { | |
67 | char tmp[32]; | |
68 | size_t size = sprintf(tmp, "%u\n", val); | |
69 | ||
70 | return simple_read_from_buffer(buf, len, ppos, tmp, size); | |
71 | } | |
72 | ||
73 | static ssize_t fuse_conn_limit_write(struct file *file, const char __user *buf, | |
74 | size_t count, loff_t *ppos, unsigned *val, | |
75 | unsigned global_limit) | |
76 | { | |
77 | unsigned long t; | |
78 | char tmp[32]; | |
79 | unsigned limit = (1 << 16) - 1; | |
80 | int err; | |
81 | ||
82 | if (*ppos || count >= sizeof(tmp) - 1) | |
83 | return -EINVAL; | |
84 | ||
85 | if (copy_from_user(tmp, buf, count)) | |
86 | return -EINVAL; | |
87 | ||
88 | tmp[count] = '\0'; | |
89 | ||
90 | err = strict_strtoul(tmp, 0, &t); | |
91 | if (err) | |
92 | return err; | |
93 | ||
94 | if (!capable(CAP_SYS_ADMIN)) | |
95 | limit = min(limit, global_limit); | |
96 | ||
97 | if (t > limit) | |
98 | return -EINVAL; | |
99 | ||
100 | *val = t; | |
101 | ||
102 | return count; | |
103 | } | |
104 | ||
105 | static ssize_t fuse_conn_max_background_read(struct file *file, | |
106 | char __user *buf, size_t len, | |
107 | loff_t *ppos) | |
108 | { | |
109 | struct fuse_conn *fc; | |
110 | unsigned val; | |
111 | ||
112 | fc = fuse_ctl_file_conn_get(file); | |
113 | if (!fc) | |
114 | return 0; | |
115 | ||
116 | val = fc->max_background; | |
117 | fuse_conn_put(fc); | |
118 | ||
119 | return fuse_conn_limit_read(file, buf, len, ppos, val); | |
120 | } | |
121 | ||
122 | static ssize_t fuse_conn_max_background_write(struct file *file, | |
123 | const char __user *buf, | |
124 | size_t count, loff_t *ppos) | |
125 | { | |
126 | unsigned val; | |
127 | ssize_t ret; | |
128 | ||
129 | ret = fuse_conn_limit_write(file, buf, count, ppos, &val, | |
130 | max_user_bgreq); | |
131 | if (ret > 0) { | |
132 | struct fuse_conn *fc = fuse_ctl_file_conn_get(file); | |
133 | if (fc) { | |
134 | fc->max_background = val; | |
135 | fuse_conn_put(fc); | |
136 | } | |
137 | } | |
138 | ||
139 | return ret; | |
140 | } | |
141 | ||
142 | static ssize_t fuse_conn_congestion_threshold_read(struct file *file, | |
143 | char __user *buf, size_t len, | |
144 | loff_t *ppos) | |
145 | { | |
146 | struct fuse_conn *fc; | |
147 | unsigned val; | |
148 | ||
149 | fc = fuse_ctl_file_conn_get(file); | |
150 | if (!fc) | |
151 | return 0; | |
152 | ||
153 | val = fc->congestion_threshold; | |
154 | fuse_conn_put(fc); | |
155 | ||
156 | return fuse_conn_limit_read(file, buf, len, ppos, val); | |
157 | } | |
158 | ||
159 | static ssize_t fuse_conn_congestion_threshold_write(struct file *file, | |
160 | const char __user *buf, | |
161 | size_t count, loff_t *ppos) | |
162 | { | |
163 | unsigned val; | |
164 | ssize_t ret; | |
165 | ||
166 | ret = fuse_conn_limit_write(file, buf, count, ppos, &val, | |
167 | max_user_congthresh); | |
168 | if (ret > 0) { | |
169 | struct fuse_conn *fc = fuse_ctl_file_conn_get(file); | |
170 | if (fc) { | |
171 | fc->congestion_threshold = val; | |
172 | fuse_conn_put(fc); | |
173 | } | |
174 | } | |
175 | ||
176 | return ret; | |
177 | } | |
178 | ||
bafa9654 MS |
179 | static const struct file_operations fuse_ctl_abort_ops = { |
180 | .open = nonseekable_open, | |
181 | .write = fuse_conn_abort_write, | |
182 | }; | |
183 | ||
184 | static const struct file_operations fuse_ctl_waiting_ops = { | |
185 | .open = nonseekable_open, | |
186 | .read = fuse_conn_waiting_read, | |
187 | }; | |
188 | ||
79a9d994 CH |
189 | static const struct file_operations fuse_conn_max_background_ops = { |
190 | .open = nonseekable_open, | |
191 | .read = fuse_conn_max_background_read, | |
192 | .write = fuse_conn_max_background_write, | |
193 | }; | |
194 | ||
195 | static const struct file_operations fuse_conn_congestion_threshold_ops = { | |
196 | .open = nonseekable_open, | |
197 | .read = fuse_conn_congestion_threshold_read, | |
198 | .write = fuse_conn_congestion_threshold_write, | |
199 | }; | |
200 | ||
bafa9654 MS |
201 | static struct dentry *fuse_ctl_add_dentry(struct dentry *parent, |
202 | struct fuse_conn *fc, | |
203 | const char *name, | |
204 | int mode, int nlink, | |
754661f1 | 205 | const struct inode_operations *iop, |
bafa9654 MS |
206 | const struct file_operations *fop) |
207 | { | |
208 | struct dentry *dentry; | |
209 | struct inode *inode; | |
210 | ||
211 | BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES); | |
212 | dentry = d_alloc_name(parent, name); | |
213 | if (!dentry) | |
214 | return NULL; | |
215 | ||
216 | fc->ctl_dentry[fc->ctl_ndents++] = dentry; | |
217 | inode = new_inode(fuse_control_sb); | |
218 | if (!inode) | |
219 | return NULL; | |
220 | ||
221 | inode->i_mode = mode; | |
222 | inode->i_uid = fc->user_id; | |
223 | inode->i_gid = fc->group_id; | |
224 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
225 | /* setting ->i_op to NULL is not allowed */ | |
226 | if (iop) | |
227 | inode->i_op = iop; | |
228 | inode->i_fop = fop; | |
229 | inode->i_nlink = nlink; | |
8e18e294 | 230 | inode->i_private = fc; |
bafa9654 MS |
231 | d_add(dentry, inode); |
232 | return dentry; | |
233 | } | |
234 | ||
235 | /* | |
236 | * Add a connection to the control filesystem (if it exists). Caller | |
873302c7 | 237 | * must hold fuse_mutex |
bafa9654 MS |
238 | */ |
239 | int fuse_ctl_add_conn(struct fuse_conn *fc) | |
240 | { | |
241 | struct dentry *parent; | |
242 | char name[32]; | |
243 | ||
244 | if (!fuse_control_sb) | |
245 | return 0; | |
246 | ||
247 | parent = fuse_control_sb->s_root; | |
d8c76e6f | 248 | inc_nlink(parent->d_inode); |
b6f2fcbc | 249 | sprintf(name, "%u", fc->dev); |
bafa9654 MS |
250 | parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2, |
251 | &simple_dir_inode_operations, | |
252 | &simple_dir_operations); | |
253 | if (!parent) | |
254 | goto err; | |
255 | ||
256 | if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1, | |
79a9d994 | 257 | NULL, &fuse_ctl_waiting_ops) || |
bafa9654 | 258 | !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1, |
79a9d994 CH |
259 | NULL, &fuse_ctl_abort_ops) || |
260 | !fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600, | |
261 | 1, NULL, &fuse_conn_max_background_ops) || | |
262 | !fuse_ctl_add_dentry(parent, fc, "congestion_threshold", | |
263 | S_IFREG | 0600, 1, NULL, | |
264 | &fuse_conn_congestion_threshold_ops)) | |
bafa9654 MS |
265 | goto err; |
266 | ||
267 | return 0; | |
268 | ||
269 | err: | |
270 | fuse_ctl_remove_conn(fc); | |
271 | return -ENOMEM; | |
272 | } | |
273 | ||
274 | /* | |
275 | * Remove a connection from the control filesystem (if it exists). | |
873302c7 | 276 | * Caller must hold fuse_mutex |
bafa9654 MS |
277 | */ |
278 | void fuse_ctl_remove_conn(struct fuse_conn *fc) | |
279 | { | |
280 | int i; | |
281 | ||
282 | if (!fuse_control_sb) | |
283 | return; | |
284 | ||
285 | for (i = fc->ctl_ndents - 1; i >= 0; i--) { | |
286 | struct dentry *dentry = fc->ctl_dentry[i]; | |
8e18e294 | 287 | dentry->d_inode->i_private = NULL; |
bafa9654 MS |
288 | d_drop(dentry); |
289 | dput(dentry); | |
290 | } | |
d6db07de | 291 | drop_nlink(fuse_control_sb->s_root->d_inode); |
bafa9654 MS |
292 | } |
293 | ||
294 | static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent) | |
295 | { | |
296 | struct tree_descr empty_descr = {""}; | |
297 | struct fuse_conn *fc; | |
298 | int err; | |
299 | ||
300 | err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr); | |
301 | if (err) | |
302 | return err; | |
303 | ||
304 | mutex_lock(&fuse_mutex); | |
305 | BUG_ON(fuse_control_sb); | |
306 | fuse_control_sb = sb; | |
307 | list_for_each_entry(fc, &fuse_conn_list, entry) { | |
308 | err = fuse_ctl_add_conn(fc); | |
309 | if (err) { | |
310 | fuse_control_sb = NULL; | |
311 | mutex_unlock(&fuse_mutex); | |
312 | return err; | |
313 | } | |
314 | } | |
315 | mutex_unlock(&fuse_mutex); | |
316 | ||
317 | return 0; | |
318 | } | |
319 | ||
320 | static int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags, | |
321 | const char *dev_name, void *raw_data, | |
322 | struct vfsmount *mnt) | |
323 | { | |
324 | return get_sb_single(fs_type, flags, raw_data, | |
325 | fuse_ctl_fill_super, mnt); | |
326 | } | |
327 | ||
328 | static void fuse_ctl_kill_sb(struct super_block *sb) | |
329 | { | |
ff795447 MS |
330 | struct fuse_conn *fc; |
331 | ||
bafa9654 MS |
332 | mutex_lock(&fuse_mutex); |
333 | fuse_control_sb = NULL; | |
ff795447 MS |
334 | list_for_each_entry(fc, &fuse_conn_list, entry) |
335 | fc->ctl_ndents = 0; | |
bafa9654 MS |
336 | mutex_unlock(&fuse_mutex); |
337 | ||
338 | kill_litter_super(sb); | |
339 | } | |
340 | ||
341 | static struct file_system_type fuse_ctl_fs_type = { | |
342 | .owner = THIS_MODULE, | |
343 | .name = "fusectl", | |
344 | .get_sb = fuse_ctl_get_sb, | |
345 | .kill_sb = fuse_ctl_kill_sb, | |
346 | }; | |
347 | ||
348 | int __init fuse_ctl_init(void) | |
349 | { | |
350 | return register_filesystem(&fuse_ctl_fs_type); | |
351 | } | |
352 | ||
353 | void fuse_ctl_cleanup(void) | |
354 | { | |
355 | unregister_filesystem(&fuse_ctl_fs_type); | |
356 | } |