perf tools: Fix a build error on arm64 with clang
[linux-2.6-microblaze.git] / fs / fuse / control.c
1 /*
2   FUSE: Filesystem in Userspace
3   Copyright (C) 2001-2008  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 #include <linux/fs_context.h>
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  */
21 static struct super_block *fuse_control_sb;
22
23 static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
24 {
25         struct fuse_conn *fc;
26         mutex_lock(&fuse_mutex);
27         fc = file_inode(file)->i_private;
28         if (fc)
29                 fc = fuse_conn_get(fc);
30         mutex_unlock(&fuse_mutex);
31         return fc;
32 }
33
34 static 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) {
39                 if (fc->abort_err)
40                         fc->aborted = true;
41                 fuse_abort_conn(fc);
42                 fuse_conn_put(fc);
43         }
44         return count;
45 }
46
47 static 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) {
54                 long value;
55                 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
56                 if (!fc)
57                         return 0;
58
59                 value = atomic_read(&fc->num_waiting);
60                 file->private_data = (void *)value;
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
67 static 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
76 static 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;
81         unsigned limit = (1 << 16) - 1;
82         int err;
83
84         if (*ppos)
85                 return -EINVAL;
86
87         err = kstrtoul_from_user(buf, count, 0, &t);
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
102 static 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
113         val = READ_ONCE(fc->max_background);
114         fuse_conn_put(fc);
115
116         return fuse_conn_limit_read(file, buf, len, ppos, val);
117 }
118
119 static ssize_t fuse_conn_max_background_write(struct file *file,
120                                               const char __user *buf,
121                                               size_t count, loff_t *ppos)
122 {
123         unsigned val;
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) {
131                         spin_lock(&fc->bg_lock);
132                         fc->max_background = val;
133                         fc->blocked = fc->num_background >= fc->max_background;
134                         if (!fc->blocked)
135                                 wake_up(&fc->blocked_waitq);
136                         spin_unlock(&fc->bg_lock);
137                         fuse_conn_put(fc);
138                 }
139         }
140
141         return ret;
142 }
143
144 static 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
155         val = READ_ONCE(fc->congestion_threshold);
156         fuse_conn_put(fc);
157
158         return fuse_conn_limit_read(file, buf, len, ppos, val);
159 }
160
161 static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
162                                                     const char __user *buf,
163                                                     size_t count, loff_t *ppos)
164 {
165         unsigned val;
166         struct fuse_conn *fc;
167         struct fuse_mount *fm;
168         ssize_t ret;
169
170         ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
171                                     max_user_congthresh);
172         if (ret <= 0)
173                 goto out;
174         fc = fuse_ctl_file_conn_get(file);
175         if (!fc)
176                 goto out;
177
178         down_read(&fc->killsb);
179         spin_lock(&fc->bg_lock);
180         fc->congestion_threshold = val;
181
182         /*
183          * Get any fuse_mount belonging to this fuse_conn; s_bdi is
184          * shared between all of them
185          */
186
187         if (!list_empty(&fc->mounts)) {
188                 fm = list_first_entry(&fc->mounts, struct fuse_mount, fc_entry);
189                 if (fc->num_background < fc->congestion_threshold) {
190                         clear_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC);
191                         clear_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC);
192                 } else {
193                         set_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC);
194                         set_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC);
195                 }
196         }
197         spin_unlock(&fc->bg_lock);
198         up_read(&fc->killsb);
199         fuse_conn_put(fc);
200 out:
201         return ret;
202 }
203
204 static const struct file_operations fuse_ctl_abort_ops = {
205         .open = nonseekable_open,
206         .write = fuse_conn_abort_write,
207         .llseek = no_llseek,
208 };
209
210 static const struct file_operations fuse_ctl_waiting_ops = {
211         .open = nonseekable_open,
212         .read = fuse_conn_waiting_read,
213         .llseek = no_llseek,
214 };
215
216 static const struct file_operations fuse_conn_max_background_ops = {
217         .open = nonseekable_open,
218         .read = fuse_conn_max_background_read,
219         .write = fuse_conn_max_background_write,
220         .llseek = no_llseek,
221 };
222
223 static const struct file_operations fuse_conn_congestion_threshold_ops = {
224         .open = nonseekable_open,
225         .read = fuse_conn_congestion_threshold_read,
226         .write = fuse_conn_congestion_threshold_write,
227         .llseek = no_llseek,
228 };
229
230 static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
231                                           struct fuse_conn *fc,
232                                           const char *name,
233                                           int mode, int nlink,
234                                           const struct inode_operations *iop,
235                                           const struct file_operations *fop)
236 {
237         struct dentry *dentry;
238         struct inode *inode;
239
240         BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
241         dentry = d_alloc_name(parent, name);
242         if (!dentry)
243                 return NULL;
244
245         inode = new_inode(fuse_control_sb);
246         if (!inode) {
247                 dput(dentry);
248                 return NULL;
249         }
250
251         inode->i_ino = get_next_ino();
252         inode->i_mode = mode;
253         inode->i_uid = fc->user_id;
254         inode->i_gid = fc->group_id;
255         inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
256         /* setting ->i_op to NULL is not allowed */
257         if (iop)
258                 inode->i_op = iop;
259         inode->i_fop = fop;
260         set_nlink(inode, nlink);
261         inode->i_private = fc;
262         d_add(dentry, inode);
263
264         fc->ctl_dentry[fc->ctl_ndents++] = dentry;
265
266         return dentry;
267 }
268
269 /*
270  * Add a connection to the control filesystem (if it exists).  Caller
271  * must hold fuse_mutex
272  */
273 int fuse_ctl_add_conn(struct fuse_conn *fc)
274 {
275         struct dentry *parent;
276         char name[32];
277
278         if (!fuse_control_sb)
279                 return 0;
280
281         parent = fuse_control_sb->s_root;
282         inc_nlink(d_inode(parent));
283         sprintf(name, "%u", fc->dev);
284         parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
285                                      &simple_dir_inode_operations,
286                                      &simple_dir_operations);
287         if (!parent)
288                 goto err;
289
290         if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
291                                  NULL, &fuse_ctl_waiting_ops) ||
292             !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
293                                  NULL, &fuse_ctl_abort_ops) ||
294             !fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600,
295                                  1, NULL, &fuse_conn_max_background_ops) ||
296             !fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
297                                  S_IFREG | 0600, 1, NULL,
298                                  &fuse_conn_congestion_threshold_ops))
299                 goto err;
300
301         return 0;
302
303  err:
304         fuse_ctl_remove_conn(fc);
305         return -ENOMEM;
306 }
307
308 /*
309  * Remove a connection from the control filesystem (if it exists).
310  * Caller must hold fuse_mutex
311  */
312 void fuse_ctl_remove_conn(struct fuse_conn *fc)
313 {
314         int i;
315
316         if (!fuse_control_sb)
317                 return;
318
319         for (i = fc->ctl_ndents - 1; i >= 0; i--) {
320                 struct dentry *dentry = fc->ctl_dentry[i];
321                 d_inode(dentry)->i_private = NULL;
322                 if (!i) {
323                         /* Get rid of submounts: */
324                         d_invalidate(dentry);
325                 }
326                 dput(dentry);
327         }
328         drop_nlink(d_inode(fuse_control_sb->s_root));
329 }
330
331 static int fuse_ctl_fill_super(struct super_block *sb, struct fs_context *fctx)
332 {
333         static const struct tree_descr empty_descr = {""};
334         struct fuse_conn *fc;
335         int err;
336
337         err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
338         if (err)
339                 return err;
340
341         mutex_lock(&fuse_mutex);
342         BUG_ON(fuse_control_sb);
343         fuse_control_sb = sb;
344         list_for_each_entry(fc, &fuse_conn_list, entry) {
345                 err = fuse_ctl_add_conn(fc);
346                 if (err) {
347                         fuse_control_sb = NULL;
348                         mutex_unlock(&fuse_mutex);
349                         return err;
350                 }
351         }
352         mutex_unlock(&fuse_mutex);
353
354         return 0;
355 }
356
357 static int fuse_ctl_get_tree(struct fs_context *fc)
358 {
359         return get_tree_single(fc, fuse_ctl_fill_super);
360 }
361
362 static const struct fs_context_operations fuse_ctl_context_ops = {
363         .get_tree       = fuse_ctl_get_tree,
364 };
365
366 static int fuse_ctl_init_fs_context(struct fs_context *fc)
367 {
368         fc->ops = &fuse_ctl_context_ops;
369         return 0;
370 }
371
372 static void fuse_ctl_kill_sb(struct super_block *sb)
373 {
374         struct fuse_conn *fc;
375
376         mutex_lock(&fuse_mutex);
377         fuse_control_sb = NULL;
378         list_for_each_entry(fc, &fuse_conn_list, entry)
379                 fc->ctl_ndents = 0;
380         mutex_unlock(&fuse_mutex);
381
382         kill_litter_super(sb);
383 }
384
385 static struct file_system_type fuse_ctl_fs_type = {
386         .owner          = THIS_MODULE,
387         .name           = "fusectl",
388         .init_fs_context = fuse_ctl_init_fs_context,
389         .kill_sb        = fuse_ctl_kill_sb,
390 };
391 MODULE_ALIAS_FS("fusectl");
392
393 int __init fuse_ctl_init(void)
394 {
395         return register_filesystem(&fuse_ctl_fs_type);
396 }
397
398 void __exit fuse_ctl_cleanup(void)
399 {
400         unregister_filesystem(&fuse_ctl_fs_type);
401 }