]> Git Repo - linux.git/blame - fs/fuse/control.c
Linux 6.14-rc3
[linux.git] / fs / fuse / control.c
CommitLineData
bafa9654
MS
1/*
2 FUSE: Filesystem in Userspace
1729a16c 3 Copyright (C) 2001-2008 Miklos Szeredi <[email protected]>
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>
29cc02d9 13#include <linux/fs_context.h>
bafa9654
MS
14
15#define FUSE_CTL_SUPER_MAGIC 0x65735543
16
17/*
18 * This is non-NULL when the single instance of the control filesystem
19 * exists. Protected by fuse_mutex
20 */
21static struct super_block *fuse_control_sb;
22
23static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
24{
25 struct fuse_conn *fc;
26 mutex_lock(&fuse_mutex);
496ad9aa 27 fc = file_inode(file)->i_private;
bafa9654
MS
28 if (fc)
29 fc = fuse_conn_get(fc);
30 mutex_unlock(&fuse_mutex);
31 return fc;
32}
33
34static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf,
35 size_t count, loff_t *ppos)
36{
37 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
38 if (fc) {
eb98e3bd
MS
39 if (fc->abort_err)
40 fc->aborted = true;
41 fuse_abort_conn(fc);
bafa9654
MS
42 fuse_conn_put(fc);
43 }
44 return count;
45}
46
47static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf,
48 size_t len, loff_t *ppos)
49{
50 char tmp[32];
51 size_t size;
52
53 if (!*ppos) {
1729a16c 54 long value;
bafa9654
MS
55 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
56 if (!fc)
57 return 0;
58
1729a16c
MS
59 value = atomic_read(&fc->num_waiting);
60 file->private_data = (void *)value;
bafa9654
MS
61 fuse_conn_put(fc);
62 }
63 size = sprintf(tmp, "%ld\n", (long)file->private_data);
64 return simple_read_from_buffer(buf, len, ppos, tmp, size);
65}
66
79a9d994
CH
67static ssize_t fuse_conn_limit_read(struct file *file, char __user *buf,
68 size_t len, loff_t *ppos, unsigned val)
69{
70 char tmp[32];
71 size_t size = sprintf(tmp, "%u\n", val);
72
73 return simple_read_from_buffer(buf, len, ppos, tmp, size);
74}
75
76static ssize_t fuse_conn_limit_write(struct file *file, const char __user *buf,
77 size_t count, loff_t *ppos, unsigned *val,
78 unsigned global_limit)
79{
80 unsigned long t;
79a9d994
CH
81 unsigned limit = (1 << 16) - 1;
82 int err;
83
e2690695 84 if (*ppos)
79a9d994
CH
85 return -EINVAL;
86
e2690695 87 err = kstrtoul_from_user(buf, count, 0, &t);
79a9d994
CH
88 if (err)
89 return err;
90
91 if (!capable(CAP_SYS_ADMIN))
92 limit = min(limit, global_limit);
93
94 if (t > limit)
95 return -EINVAL;
96
97 *val = t;
98
99 return count;
100}
101
102static ssize_t fuse_conn_max_background_read(struct file *file,
103 char __user *buf, size_t len,
104 loff_t *ppos)
105{
106 struct fuse_conn *fc;
107 unsigned val;
108
109 fc = fuse_ctl_file_conn_get(file);
110 if (!fc)
111 return 0;
112
2a23f2b8 113 val = READ_ONCE(fc->max_background);
79a9d994
CH
114 fuse_conn_put(fc);
115
116 return fuse_conn_limit_read(file, buf, len, ppos, val);
117}
118
119static ssize_t fuse_conn_max_background_write(struct file *file,
120 const char __user *buf,
121 size_t count, loff_t *ppos)
122{
3f649ab7 123 unsigned val;
79a9d994
CH
124 ssize_t ret;
125
126 ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
127 max_user_bgreq);
128 if (ret > 0) {
129 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
130 if (fc) {
ae2dffa3 131 spin_lock(&fc->bg_lock);
79a9d994 132 fc->max_background = val;
2b30a533
KT
133 fc->blocked = fc->num_background >= fc->max_background;
134 if (!fc->blocked)
135 wake_up(&fc->blocked_waitq);
ae2dffa3 136 spin_unlock(&fc->bg_lock);
79a9d994
CH
137 fuse_conn_put(fc);
138 }
139 }
140
141 return ret;
142}
143
144static ssize_t fuse_conn_congestion_threshold_read(struct file *file,
145 char __user *buf, size_t len,
146 loff_t *ppos)
147{
148 struct fuse_conn *fc;
149 unsigned val;
150
151 fc = fuse_ctl_file_conn_get(file);
152 if (!fc)
153 return 0;
154
2a23f2b8 155 val = READ_ONCE(fc->congestion_threshold);
79a9d994
CH
156 fuse_conn_put(fc);
157
158 return fuse_conn_limit_read(file, buf, len, ppos, val);
159}
160
161static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
162 const char __user *buf,
163 size_t count, loff_t *ppos)
164{
3f649ab7 165 unsigned val;
2b30a533 166 struct fuse_conn *fc;
79a9d994
CH
167 ssize_t ret;
168
169 ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
170 max_user_congthresh);
2b30a533
KT
171 if (ret <= 0)
172 goto out;
173 fc = fuse_ctl_file_conn_get(file);
174 if (!fc)
175 goto out;
176
efc4105a 177 WRITE_ONCE(fc->congestion_threshold, val);
2b30a533
KT
178 fuse_conn_put(fc);
179out:
79a9d994
CH
180 return ret;
181}
182
bafa9654
MS
183static const struct file_operations fuse_ctl_abort_ops = {
184 .open = nonseekable_open,
185 .write = fuse_conn_abort_write,
186};
187
188static const struct file_operations fuse_ctl_waiting_ops = {
189 .open = nonseekable_open,
190 .read = fuse_conn_waiting_read,
191};
192
79a9d994
CH
193static const struct file_operations fuse_conn_max_background_ops = {
194 .open = nonseekable_open,
195 .read = fuse_conn_max_background_read,
196 .write = fuse_conn_max_background_write,
197};
198
199static const struct file_operations fuse_conn_congestion_threshold_ops = {
200 .open = nonseekable_open,
201 .read = fuse_conn_congestion_threshold_read,
202 .write = fuse_conn_congestion_threshold_write,
203};
204
bafa9654
MS
205static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
206 struct fuse_conn *fc,
207 const char *name,
208 int mode, int nlink,
754661f1 209 const struct inode_operations *iop,
bafa9654
MS
210 const struct file_operations *fop)
211{
212 struct dentry *dentry;
213 struct inode *inode;
214
215 BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
216 dentry = d_alloc_name(parent, name);
217 if (!dentry)
218 return NULL;
219
bafa9654 220 inode = new_inode(fuse_control_sb);
6becdb60
MS
221 if (!inode) {
222 dput(dentry);
bafa9654 223 return NULL;
6becdb60 224 }
bafa9654 225
85fe4025 226 inode->i_ino = get_next_ino();
bafa9654
MS
227 inode->i_mode = mode;
228 inode->i_uid = fc->user_id;
229 inode->i_gid = fc->group_id;
3c0d5df2 230 simple_inode_init_ts(inode);
bafa9654
MS
231 /* setting ->i_op to NULL is not allowed */
232 if (iop)
233 inode->i_op = iop;
234 inode->i_fop = fop;
bfe86848 235 set_nlink(inode, nlink);
8e18e294 236 inode->i_private = fc;
bafa9654 237 d_add(dentry, inode);
6becdb60
MS
238
239 fc->ctl_dentry[fc->ctl_ndents++] = dentry;
240
bafa9654
MS
241 return dentry;
242}
243
244/*
245 * Add a connection to the control filesystem (if it exists). Caller
873302c7 246 * must hold fuse_mutex
bafa9654
MS
247 */
248int fuse_ctl_add_conn(struct fuse_conn *fc)
249{
250 struct dentry *parent;
251 char name[32];
252
c6479780 253 if (!fuse_control_sb || fc->no_control)
bafa9654
MS
254 return 0;
255
256 parent = fuse_control_sb->s_root;
2b0143b5 257 inc_nlink(d_inode(parent));
b6f2fcbc 258 sprintf(name, "%u", fc->dev);
bafa9654
MS
259 parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
260 &simple_dir_inode_operations,
261 &simple_dir_operations);
262 if (!parent)
263 goto err;
264
265 if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
79a9d994 266 NULL, &fuse_ctl_waiting_ops) ||
bafa9654 267 !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
79a9d994
CH
268 NULL, &fuse_ctl_abort_ops) ||
269 !fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600,
270 1, NULL, &fuse_conn_max_background_ops) ||
271 !fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
272 S_IFREG | 0600, 1, NULL,
273 &fuse_conn_congestion_threshold_ops))
bafa9654
MS
274 goto err;
275
276 return 0;
277
278 err:
279 fuse_ctl_remove_conn(fc);
280 return -ENOMEM;
281}
282
283/*
284 * Remove a connection from the control filesystem (if it exists).
873302c7 285 * Caller must hold fuse_mutex
bafa9654
MS
286 */
287void fuse_ctl_remove_conn(struct fuse_conn *fc)
288{
289 int i;
290
c6479780 291 if (!fuse_control_sb || fc->no_control)
bafa9654
MS
292 return;
293
294 for (i = fc->ctl_ndents - 1; i >= 0; i--) {
295 struct dentry *dentry = fc->ctl_dentry[i];
2b0143b5 296 d_inode(dentry)->i_private = NULL;
6becdb60
MS
297 if (!i) {
298 /* Get rid of submounts: */
299 d_invalidate(dentry);
300 }
bafa9654
MS
301 dput(dentry);
302 }
2b0143b5 303 drop_nlink(d_inode(fuse_control_sb->s_root));
bafa9654
MS
304}
305
84c21507 306static int fuse_ctl_fill_super(struct super_block *sb, struct fs_context *fsc)
bafa9654 307{
cda37124 308 static const struct tree_descr empty_descr = {""};
bafa9654
MS
309 struct fuse_conn *fc;
310 int err;
311
312 err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
313 if (err)
314 return err;
315
316 mutex_lock(&fuse_mutex);
317 BUG_ON(fuse_control_sb);
318 fuse_control_sb = sb;
319 list_for_each_entry(fc, &fuse_conn_list, entry) {
320 err = fuse_ctl_add_conn(fc);
321 if (err) {
322 fuse_control_sb = NULL;
323 mutex_unlock(&fuse_mutex);
324 return err;
325 }
326 }
327 mutex_unlock(&fuse_mutex);
328
329 return 0;
330}
331
84c21507 332static int fuse_ctl_get_tree(struct fs_context *fsc)
bafa9654 333{
84c21507 334 return get_tree_single(fsc, fuse_ctl_fill_super);
29cc02d9
DH
335}
336
337static const struct fs_context_operations fuse_ctl_context_ops = {
338 .get_tree = fuse_ctl_get_tree,
339};
340
84c21507 341static int fuse_ctl_init_fs_context(struct fs_context *fsc)
29cc02d9 342{
84c21507 343 fsc->ops = &fuse_ctl_context_ops;
29cc02d9 344 return 0;
bafa9654
MS
345}
346
347static void fuse_ctl_kill_sb(struct super_block *sb)
348{
ff795447
MS
349 struct fuse_conn *fc;
350
bafa9654
MS
351 mutex_lock(&fuse_mutex);
352 fuse_control_sb = NULL;
ff795447
MS
353 list_for_each_entry(fc, &fuse_conn_list, entry)
354 fc->ctl_ndents = 0;
bafa9654
MS
355 mutex_unlock(&fuse_mutex);
356
357 kill_litter_super(sb);
358}
359
360static struct file_system_type fuse_ctl_fs_type = {
361 .owner = THIS_MODULE,
362 .name = "fusectl",
29cc02d9 363 .init_fs_context = fuse_ctl_init_fs_context,
bafa9654
MS
364 .kill_sb = fuse_ctl_kill_sb,
365};
7f78e035 366MODULE_ALIAS_FS("fusectl");
bafa9654
MS
367
368int __init fuse_ctl_init(void)
369{
370 return register_filesystem(&fuse_ctl_fs_type);
371}
372
7736e8cc 373void __exit fuse_ctl_cleanup(void)
bafa9654
MS
374{
375 unregister_filesystem(&fuse_ctl_fs_type);
376}
This page took 1.095111 seconds and 4 git commands to generate.