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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
18
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);
26 fc = file_inode(file)->i_private;
27 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 long value;
52 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
53 if (!fc)
54 return 0;
55
56 value = atomic_read(&fc->num_waiting);
57 file->private_data = (void *)value;
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
64static 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
73static 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 unsigned limit = (1 << 16) - 1;
79 int err;
80
81 if (*ppos)
82 return -EINVAL;
83
84 err = kstrtoul_from_user(buf, count, 0, &t);
85 if (err)
86 return err;
87
88 if (!capable(CAP_SYS_ADMIN))
89 limit = min(limit, global_limit);
90
91 if (t > limit)
92 return -EINVAL;
93
94 *val = t;
95
96 return count;
97}
98
99static ssize_t fuse_conn_max_background_read(struct file *file,
100 char __user *buf, size_t len,
101 loff_t *ppos)
102{
103 struct fuse_conn *fc;
104 unsigned val;
105
106 fc = fuse_ctl_file_conn_get(file);
107 if (!fc)
108 return 0;
109
110 val = fc->max_background;
111 fuse_conn_put(fc);
112
113 return fuse_conn_limit_read(file, buf, len, ppos, val);
114}
115
116static ssize_t fuse_conn_max_background_write(struct file *file,
117 const char __user *buf,
118 size_t count, loff_t *ppos)
119{
120 unsigned uninitialized_var(val);
121 ssize_t ret;
122
123 ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
124 max_user_bgreq);
125 if (ret > 0) {
126 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
127 if (fc) {
128 fc->max_background = val;
129 fuse_conn_put(fc);
130 }
131 }
132
133 return ret;
134}
135
136static ssize_t fuse_conn_congestion_threshold_read(struct file *file,
137 char __user *buf, size_t len,
138 loff_t *ppos)
139{
140 struct fuse_conn *fc;
141 unsigned val;
142
143 fc = fuse_ctl_file_conn_get(file);
144 if (!fc)
145 return 0;
146
147 val = fc->congestion_threshold;
148 fuse_conn_put(fc);
149
150 return fuse_conn_limit_read(file, buf, len, ppos, val);
151}
152
153static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
154 const char __user *buf,
155 size_t count, loff_t *ppos)
156{
157 unsigned uninitialized_var(val);
158 ssize_t ret;
159
160 ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
161 max_user_congthresh);
162 if (ret > 0) {
163 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
164 if (fc) {
165 fc->congestion_threshold = val;
166 fuse_conn_put(fc);
167 }
168 }
169
170 return ret;
171}
172
173static const struct file_operations fuse_ctl_abort_ops = {
174 .open = nonseekable_open,
175 .write = fuse_conn_abort_write,
176 .llseek = no_llseek,
177};
178
179static const struct file_operations fuse_ctl_waiting_ops = {
180 .open = nonseekable_open,
181 .read = fuse_conn_waiting_read,
182 .llseek = no_llseek,
183};
184
185static const struct file_operations fuse_conn_max_background_ops = {
186 .open = nonseekable_open,
187 .read = fuse_conn_max_background_read,
188 .write = fuse_conn_max_background_write,
189 .llseek = no_llseek,
190};
191
192static const struct file_operations fuse_conn_congestion_threshold_ops = {
193 .open = nonseekable_open,
194 .read = fuse_conn_congestion_threshold_read,
195 .write = fuse_conn_congestion_threshold_write,
196 .llseek = no_llseek,
197};
198
199static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
200 struct fuse_conn *fc,
201 const char *name,
202 int mode, int nlink,
203 const struct inode_operations *iop,
204 const struct file_operations *fop)
205{
206 struct dentry *dentry;
207 struct inode *inode;
208
209 BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
210 dentry = d_alloc_name(parent, name);
211 if (!dentry)
212 return NULL;
213
214 fc->ctl_dentry[fc->ctl_ndents++] = dentry;
215 inode = new_inode(fuse_control_sb);
216 if (!inode)
217 return NULL;
218
219 inode->i_ino = get_next_ino();
220 inode->i_mode = mode;
221 inode->i_uid = fc->user_id;
222 inode->i_gid = fc->group_id;
223 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
224
225 if (iop)
226 inode->i_op = iop;
227 inode->i_fop = fop;
228 set_nlink(inode, nlink);
229 inode->i_private = fc;
230 d_add(dentry, inode);
231 return dentry;
232}
233
234
235
236
237
238int fuse_ctl_add_conn(struct fuse_conn *fc)
239{
240 struct dentry *parent;
241 char name[32];
242
243 if (!fuse_control_sb)
244 return 0;
245
246 parent = fuse_control_sb->s_root;
247 inc_nlink(parent->d_inode);
248 sprintf(name, "%u", fc->dev);
249 parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
250 &simple_dir_inode_operations,
251 &simple_dir_operations);
252 if (!parent)
253 goto err;
254
255 if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
256 NULL, &fuse_ctl_waiting_ops) ||
257 !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
258 NULL, &fuse_ctl_abort_ops) ||
259 !fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600,
260 1, NULL, &fuse_conn_max_background_ops) ||
261 !fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
262 S_IFREG | 0600, 1, NULL,
263 &fuse_conn_congestion_threshold_ops))
264 goto err;
265
266 return 0;
267
268 err:
269 fuse_ctl_remove_conn(fc);
270 return -ENOMEM;
271}
272
273
274
275
276
277void fuse_ctl_remove_conn(struct fuse_conn *fc)
278{
279 int i;
280
281 if (!fuse_control_sb)
282 return;
283
284 for (i = fc->ctl_ndents - 1; i >= 0; i--) {
285 struct dentry *dentry = fc->ctl_dentry[i];
286 dentry->d_inode->i_private = NULL;
287 d_drop(dentry);
288 dput(dentry);
289 }
290 drop_nlink(fuse_control_sb->s_root->d_inode);
291}
292
293static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
294{
295 struct tree_descr empty_descr = {""};
296 struct fuse_conn *fc;
297 int err;
298
299 err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
300 if (err)
301 return err;
302
303 mutex_lock(&fuse_mutex);
304 BUG_ON(fuse_control_sb);
305 fuse_control_sb = sb;
306 list_for_each_entry(fc, &fuse_conn_list, entry) {
307 err = fuse_ctl_add_conn(fc);
308 if (err) {
309 fuse_control_sb = NULL;
310 mutex_unlock(&fuse_mutex);
311 return err;
312 }
313 }
314 mutex_unlock(&fuse_mutex);
315
316 return 0;
317}
318
319static struct dentry *fuse_ctl_mount(struct file_system_type *fs_type,
320 int flags, const char *dev_name, void *raw_data)
321{
322 return mount_single(fs_type, flags, raw_data, fuse_ctl_fill_super);
323}
324
325static void fuse_ctl_kill_sb(struct super_block *sb)
326{
327 struct fuse_conn *fc;
328
329 mutex_lock(&fuse_mutex);
330 fuse_control_sb = NULL;
331 list_for_each_entry(fc, &fuse_conn_list, entry)
332 fc->ctl_ndents = 0;
333 mutex_unlock(&fuse_mutex);
334
335 kill_litter_super(sb);
336}
337
338static struct file_system_type fuse_ctl_fs_type = {
339 .owner = THIS_MODULE,
340 .name = "fusectl",
341 .mount = fuse_ctl_mount,
342 .kill_sb = fuse_ctl_kill_sb,
343};
344MODULE_ALIAS_FS("fusectl");
345
346int __init fuse_ctl_init(void)
347{
348 return register_filesystem(&fuse_ctl_fs_type);
349}
350
351void fuse_ctl_cleanup(void)
352{
353 unregister_filesystem(&fuse_ctl_fs_type);
354}
355
