1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * inode.c - part of tracefs, a pseudo file system for activating tracing |
4 | * |
5 | * Based on debugfs by: Greg Kroah-Hartman <greg@kroah.com> |
6 | * |
7 | * Copyright (C) 2014 Red Hat Inc, author: Steven Rostedt <srostedt@redhat.com> |
8 | * |
9 | * tracefs is the file system that is used by the tracing infrastructure. |
10 | */ |
11 | |
12 | #include <linux/module.h> |
13 | #include <linux/fs.h> |
14 | #include <linux/mount.h> |
15 | #include <linux/kobject.h> |
16 | #include <linux/namei.h> |
17 | #include <linux/tracefs.h> |
18 | #include <linux/fsnotify.h> |
19 | #include <linux/security.h> |
20 | #include <linux/seq_file.h> |
21 | #include <linux/parser.h> |
22 | #include <linux/magic.h> |
23 | #include <linux/slab.h> |
24 | #include "internal.h" |
25 | |
26 | #define TRACEFS_DEFAULT_MODE 0700 |
27 | static struct kmem_cache *tracefs_inode_cachep __ro_after_init; |
28 | |
29 | static struct vfsmount *tracefs_mount; |
30 | static int tracefs_mount_count; |
31 | static bool tracefs_registered; |
32 | |
33 | static struct inode *tracefs_alloc_inode(struct super_block *sb) |
34 | { |
35 | struct tracefs_inode *ti; |
36 | |
37 | ti = kmem_cache_alloc(cachep: tracefs_inode_cachep, GFP_KERNEL); |
38 | if (!ti) |
39 | return NULL; |
40 | |
41 | ti->flags = 0; |
42 | |
43 | return &ti->vfs_inode; |
44 | } |
45 | |
46 | static void tracefs_free_inode(struct inode *inode) |
47 | { |
48 | kmem_cache_free(s: tracefs_inode_cachep, objp: get_tracefs(inode)); |
49 | } |
50 | |
51 | static ssize_t default_read_file(struct file *file, char __user *buf, |
52 | size_t count, loff_t *ppos) |
53 | { |
54 | return 0; |
55 | } |
56 | |
57 | static ssize_t default_write_file(struct file *file, const char __user *buf, |
58 | size_t count, loff_t *ppos) |
59 | { |
60 | return count; |
61 | } |
62 | |
63 | static const struct file_operations tracefs_file_operations = { |
64 | .read = default_read_file, |
65 | .write = default_write_file, |
66 | .open = simple_open, |
67 | .llseek = noop_llseek, |
68 | }; |
69 | |
70 | static struct tracefs_dir_ops { |
71 | int (*mkdir)(const char *name); |
72 | int (*rmdir)(const char *name); |
73 | } tracefs_ops __ro_after_init; |
74 | |
75 | static char *get_dname(struct dentry *dentry) |
76 | { |
77 | const char *dname; |
78 | char *name; |
79 | int len = dentry->d_name.len; |
80 | |
81 | dname = dentry->d_name.name; |
82 | name = kmalloc(size: len + 1, GFP_KERNEL); |
83 | if (!name) |
84 | return NULL; |
85 | memcpy(name, dname, len); |
86 | name[len] = 0; |
87 | return name; |
88 | } |
89 | |
90 | static int tracefs_syscall_mkdir(struct mnt_idmap *idmap, |
91 | struct inode *inode, struct dentry *dentry, |
92 | umode_t mode) |
93 | { |
94 | char *name; |
95 | int ret; |
96 | |
97 | name = get_dname(dentry); |
98 | if (!name) |
99 | return -ENOMEM; |
100 | |
101 | /* |
102 | * The mkdir call can call the generic functions that create |
103 | * the files within the tracefs system. It is up to the individual |
104 | * mkdir routine to handle races. |
105 | */ |
106 | inode_unlock(inode); |
107 | ret = tracefs_ops.mkdir(name); |
108 | inode_lock(inode); |
109 | |
110 | kfree(objp: name); |
111 | |
112 | return ret; |
113 | } |
114 | |
115 | static int tracefs_syscall_rmdir(struct inode *inode, struct dentry *dentry) |
116 | { |
117 | char *name; |
118 | int ret; |
119 | |
120 | name = get_dname(dentry); |
121 | if (!name) |
122 | return -ENOMEM; |
123 | |
124 | /* |
125 | * The rmdir call can call the generic functions that create |
126 | * the files within the tracefs system. It is up to the individual |
127 | * rmdir routine to handle races. |
128 | * This time we need to unlock not only the parent (inode) but |
129 | * also the directory that is being deleted. |
130 | */ |
131 | inode_unlock(inode); |
132 | inode_unlock(inode: d_inode(dentry)); |
133 | |
134 | ret = tracefs_ops.rmdir(name); |
135 | |
136 | inode_lock_nested(inode, subclass: I_MUTEX_PARENT); |
137 | inode_lock(inode: d_inode(dentry)); |
138 | |
139 | kfree(objp: name); |
140 | |
141 | return ret; |
142 | } |
143 | |
144 | static const struct inode_operations tracefs_dir_inode_operations = { |
145 | .lookup = simple_lookup, |
146 | .mkdir = tracefs_syscall_mkdir, |
147 | .rmdir = tracefs_syscall_rmdir, |
148 | }; |
149 | |
150 | struct inode *tracefs_get_inode(struct super_block *sb) |
151 | { |
152 | struct inode *inode = new_inode(sb); |
153 | if (inode) { |
154 | inode->i_ino = get_next_ino(); |
155 | simple_inode_init_ts(inode); |
156 | } |
157 | return inode; |
158 | } |
159 | |
160 | struct tracefs_mount_opts { |
161 | kuid_t uid; |
162 | kgid_t gid; |
163 | umode_t mode; |
164 | /* Opt_* bitfield. */ |
165 | unsigned int opts; |
166 | }; |
167 | |
168 | enum { |
169 | Opt_uid, |
170 | Opt_gid, |
171 | Opt_mode, |
172 | Opt_err |
173 | }; |
174 | |
175 | static const match_table_t tokens = { |
176 | {Opt_uid, "uid=%u" }, |
177 | {Opt_gid, "gid=%u" }, |
178 | {Opt_mode, "mode=%o" }, |
179 | {Opt_err, NULL} |
180 | }; |
181 | |
182 | struct tracefs_fs_info { |
183 | struct tracefs_mount_opts mount_opts; |
184 | }; |
185 | |
186 | static void change_gid(struct dentry *dentry, kgid_t gid) |
187 | { |
188 | if (!dentry->d_inode) |
189 | return; |
190 | dentry->d_inode->i_gid = gid; |
191 | } |
192 | |
193 | /* |
194 | * Taken from d_walk, but without he need for handling renames. |
195 | * Nothing can be renamed while walking the list, as tracefs |
196 | * does not support renames. This is only called when mounting |
197 | * or remounting the file system, to set all the files to |
198 | * the given gid. |
199 | */ |
200 | static void set_gid(struct dentry *parent, kgid_t gid) |
201 | { |
202 | struct dentry *this_parent; |
203 | struct list_head *next; |
204 | |
205 | this_parent = parent; |
206 | spin_lock(lock: &this_parent->d_lock); |
207 | |
208 | change_gid(dentry: this_parent, gid); |
209 | repeat: |
210 | next = this_parent->d_subdirs.next; |
211 | resume: |
212 | while (next != &this_parent->d_subdirs) { |
213 | struct list_head *tmp = next; |
214 | struct dentry *dentry = list_entry(tmp, struct dentry, d_child); |
215 | next = tmp->next; |
216 | |
217 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
218 | |
219 | change_gid(dentry, gid); |
220 | |
221 | if (!list_empty(head: &dentry->d_subdirs)) { |
222 | spin_unlock(lock: &this_parent->d_lock); |
223 | spin_release(&dentry->d_lock.dep_map, _RET_IP_); |
224 | this_parent = dentry; |
225 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
226 | goto repeat; |
227 | } |
228 | spin_unlock(lock: &dentry->d_lock); |
229 | } |
230 | /* |
231 | * All done at this level ... ascend and resume the search. |
232 | */ |
233 | rcu_read_lock(); |
234 | ascend: |
235 | if (this_parent != parent) { |
236 | struct dentry *child = this_parent; |
237 | this_parent = child->d_parent; |
238 | |
239 | spin_unlock(lock: &child->d_lock); |
240 | spin_lock(lock: &this_parent->d_lock); |
241 | |
242 | /* go into the first sibling still alive */ |
243 | do { |
244 | next = child->d_child.next; |
245 | if (next == &this_parent->d_subdirs) |
246 | goto ascend; |
247 | child = list_entry(next, struct dentry, d_child); |
248 | } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)); |
249 | rcu_read_unlock(); |
250 | goto resume; |
251 | } |
252 | rcu_read_unlock(); |
253 | spin_unlock(lock: &this_parent->d_lock); |
254 | return; |
255 | } |
256 | |
257 | static int tracefs_parse_options(char *data, struct tracefs_mount_opts *opts) |
258 | { |
259 | substring_t args[MAX_OPT_ARGS]; |
260 | int option; |
261 | int token; |
262 | kuid_t uid; |
263 | kgid_t gid; |
264 | char *p; |
265 | |
266 | opts->opts = 0; |
267 | opts->mode = TRACEFS_DEFAULT_MODE; |
268 | |
269 | while ((p = strsep(&data, "," )) != NULL) { |
270 | if (!*p) |
271 | continue; |
272 | |
273 | token = match_token(p, table: tokens, args); |
274 | switch (token) { |
275 | case Opt_uid: |
276 | if (match_int(&args[0], result: &option)) |
277 | return -EINVAL; |
278 | uid = make_kuid(current_user_ns(), uid: option); |
279 | if (!uid_valid(uid)) |
280 | return -EINVAL; |
281 | opts->uid = uid; |
282 | break; |
283 | case Opt_gid: |
284 | if (match_int(&args[0], result: &option)) |
285 | return -EINVAL; |
286 | gid = make_kgid(current_user_ns(), gid: option); |
287 | if (!gid_valid(gid)) |
288 | return -EINVAL; |
289 | opts->gid = gid; |
290 | break; |
291 | case Opt_mode: |
292 | if (match_octal(&args[0], result: &option)) |
293 | return -EINVAL; |
294 | opts->mode = option & S_IALLUGO; |
295 | break; |
296 | /* |
297 | * We might like to report bad mount options here; |
298 | * but traditionally tracefs has ignored all mount options |
299 | */ |
300 | } |
301 | |
302 | opts->opts |= BIT(token); |
303 | } |
304 | |
305 | return 0; |
306 | } |
307 | |
308 | static int tracefs_apply_options(struct super_block *sb, bool remount) |
309 | { |
310 | struct tracefs_fs_info *fsi = sb->s_fs_info; |
311 | struct inode *inode = d_inode(dentry: sb->s_root); |
312 | struct tracefs_mount_opts *opts = &fsi->mount_opts; |
313 | umode_t tmp_mode; |
314 | |
315 | /* |
316 | * On remount, only reset mode/uid/gid if they were provided as mount |
317 | * options. |
318 | */ |
319 | |
320 | if (!remount || opts->opts & BIT(Opt_mode)) { |
321 | tmp_mode = READ_ONCE(inode->i_mode) & ~S_IALLUGO; |
322 | tmp_mode |= opts->mode; |
323 | WRITE_ONCE(inode->i_mode, tmp_mode); |
324 | } |
325 | |
326 | if (!remount || opts->opts & BIT(Opt_uid)) |
327 | inode->i_uid = opts->uid; |
328 | |
329 | if (!remount || opts->opts & BIT(Opt_gid)) { |
330 | /* Set all the group ids to the mount option */ |
331 | set_gid(parent: sb->s_root, gid: opts->gid); |
332 | } |
333 | |
334 | return 0; |
335 | } |
336 | |
337 | static int tracefs_remount(struct super_block *sb, int *flags, char *data) |
338 | { |
339 | int err; |
340 | struct tracefs_fs_info *fsi = sb->s_fs_info; |
341 | |
342 | sync_filesystem(sb); |
343 | err = tracefs_parse_options(data, opts: &fsi->mount_opts); |
344 | if (err) |
345 | goto fail; |
346 | |
347 | tracefs_apply_options(sb, remount: true); |
348 | |
349 | fail: |
350 | return err; |
351 | } |
352 | |
353 | static int tracefs_show_options(struct seq_file *m, struct dentry *root) |
354 | { |
355 | struct tracefs_fs_info *fsi = root->d_sb->s_fs_info; |
356 | struct tracefs_mount_opts *opts = &fsi->mount_opts; |
357 | |
358 | if (!uid_eq(left: opts->uid, GLOBAL_ROOT_UID)) |
359 | seq_printf(m, ",uid=%u" , |
360 | from_kuid_munged(&init_user_ns, opts->uid)); |
361 | if (!gid_eq(opts->gid, GLOBAL_ROOT_GID)) |
362 | seq_printf(m, ",gid=%u" , |
363 | from_kgid_munged(&init_user_ns, opts->gid)); |
364 | if (opts->mode != TRACEFS_DEFAULT_MODE) |
365 | seq_printf(m, ",mode=%o" , opts->mode); |
366 | |
367 | return 0; |
368 | } |
369 | |
370 | static const struct super_operations tracefs_super_operations = { |
371 | .alloc_inode = tracefs_alloc_inode, |
372 | .free_inode = tracefs_free_inode, |
373 | .drop_inode = generic_delete_inode, |
374 | .statfs = simple_statfs, |
375 | .remount_fs = tracefs_remount, |
376 | .show_options = tracefs_show_options, |
377 | }; |
378 | |
379 | static void tracefs_dentry_iput(struct dentry *dentry, struct inode *inode) |
380 | { |
381 | struct tracefs_inode *ti; |
382 | |
383 | if (!dentry || !inode) |
384 | return; |
385 | |
386 | ti = get_tracefs(inode); |
387 | if (ti && ti->flags & TRACEFS_EVENT_INODE) |
388 | eventfs_set_ei_status_free(ti, dentry); |
389 | iput(inode); |
390 | } |
391 | |
392 | static const struct dentry_operations tracefs_dentry_operations = { |
393 | .d_iput = tracefs_dentry_iput, |
394 | }; |
395 | |
396 | static int trace_fill_super(struct super_block *sb, void *data, int silent) |
397 | { |
398 | static const struct tree_descr trace_files[] = {{"" }}; |
399 | struct tracefs_fs_info *fsi; |
400 | int err; |
401 | |
402 | fsi = kzalloc(size: sizeof(struct tracefs_fs_info), GFP_KERNEL); |
403 | sb->s_fs_info = fsi; |
404 | if (!fsi) { |
405 | err = -ENOMEM; |
406 | goto fail; |
407 | } |
408 | |
409 | err = tracefs_parse_options(data, opts: &fsi->mount_opts); |
410 | if (err) |
411 | goto fail; |
412 | |
413 | err = simple_fill_super(sb, TRACEFS_MAGIC, trace_files); |
414 | if (err) |
415 | goto fail; |
416 | |
417 | sb->s_op = &tracefs_super_operations; |
418 | sb->s_d_op = &tracefs_dentry_operations; |
419 | |
420 | tracefs_apply_options(sb, remount: false); |
421 | |
422 | return 0; |
423 | |
424 | fail: |
425 | kfree(objp: fsi); |
426 | sb->s_fs_info = NULL; |
427 | return err; |
428 | } |
429 | |
430 | static struct dentry *trace_mount(struct file_system_type *fs_type, |
431 | int flags, const char *dev_name, |
432 | void *data) |
433 | { |
434 | return mount_single(fs_type, flags, data, fill_super: trace_fill_super); |
435 | } |
436 | |
437 | static struct file_system_type trace_fs_type = { |
438 | .owner = THIS_MODULE, |
439 | .name = "tracefs" , |
440 | .mount = trace_mount, |
441 | .kill_sb = kill_litter_super, |
442 | }; |
443 | MODULE_ALIAS_FS("tracefs" ); |
444 | |
445 | struct dentry *tracefs_start_creating(const char *name, struct dentry *parent) |
446 | { |
447 | struct dentry *dentry; |
448 | int error; |
449 | |
450 | pr_debug("tracefs: creating file '%s'\n" ,name); |
451 | |
452 | error = simple_pin_fs(&trace_fs_type, mount: &tracefs_mount, |
453 | count: &tracefs_mount_count); |
454 | if (error) |
455 | return ERR_PTR(error); |
456 | |
457 | /* If the parent is not specified, we create it in the root. |
458 | * We need the root dentry to do this, which is in the super |
459 | * block. A pointer to that is in the struct vfsmount that we |
460 | * have around. |
461 | */ |
462 | if (!parent) |
463 | parent = tracefs_mount->mnt_root; |
464 | |
465 | inode_lock(inode: d_inode(dentry: parent)); |
466 | if (unlikely(IS_DEADDIR(d_inode(parent)))) |
467 | dentry = ERR_PTR(error: -ENOENT); |
468 | else |
469 | dentry = lookup_one_len(name, parent, strlen(name)); |
470 | if (!IS_ERR(ptr: dentry) && d_inode(dentry)) { |
471 | dput(dentry); |
472 | dentry = ERR_PTR(error: -EEXIST); |
473 | } |
474 | |
475 | if (IS_ERR(ptr: dentry)) { |
476 | inode_unlock(inode: d_inode(dentry: parent)); |
477 | simple_release_fs(mount: &tracefs_mount, count: &tracefs_mount_count); |
478 | } |
479 | |
480 | return dentry; |
481 | } |
482 | |
483 | struct dentry *tracefs_failed_creating(struct dentry *dentry) |
484 | { |
485 | inode_unlock(inode: d_inode(dentry: dentry->d_parent)); |
486 | dput(dentry); |
487 | simple_release_fs(mount: &tracefs_mount, count: &tracefs_mount_count); |
488 | return NULL; |
489 | } |
490 | |
491 | struct dentry *tracefs_end_creating(struct dentry *dentry) |
492 | { |
493 | inode_unlock(inode: d_inode(dentry: dentry->d_parent)); |
494 | return dentry; |
495 | } |
496 | |
497 | /** |
498 | * eventfs_start_creating - start the process of creating a dentry |
499 | * @name: Name of the file created for the dentry |
500 | * @parent: The parent dentry where this dentry will be created |
501 | * |
502 | * This is a simple helper function for the dynamically created eventfs |
503 | * files. When the directory of the eventfs files are accessed, their |
504 | * dentries are created on the fly. This function is used to start that |
505 | * process. |
506 | */ |
507 | struct dentry *eventfs_start_creating(const char *name, struct dentry *parent) |
508 | { |
509 | struct dentry *dentry; |
510 | int error; |
511 | |
512 | error = simple_pin_fs(&trace_fs_type, mount: &tracefs_mount, |
513 | count: &tracefs_mount_count); |
514 | if (error) |
515 | return ERR_PTR(error); |
516 | |
517 | /* |
518 | * If the parent is not specified, we create it in the root. |
519 | * We need the root dentry to do this, which is in the super |
520 | * block. A pointer to that is in the struct vfsmount that we |
521 | * have around. |
522 | */ |
523 | if (!parent) |
524 | parent = tracefs_mount->mnt_root; |
525 | |
526 | if (unlikely(IS_DEADDIR(parent->d_inode))) |
527 | dentry = ERR_PTR(error: -ENOENT); |
528 | else |
529 | dentry = lookup_one_len(name, parent, strlen(name)); |
530 | |
531 | if (!IS_ERR(ptr: dentry) && dentry->d_inode) { |
532 | dput(dentry); |
533 | dentry = ERR_PTR(error: -EEXIST); |
534 | } |
535 | |
536 | if (IS_ERR(ptr: dentry)) |
537 | simple_release_fs(mount: &tracefs_mount, count: &tracefs_mount_count); |
538 | |
539 | return dentry; |
540 | } |
541 | |
542 | /** |
543 | * eventfs_failed_creating - clean up a failed eventfs dentry creation |
544 | * @dentry: The dentry to clean up |
545 | * |
546 | * If after calling eventfs_start_creating(), a failure is detected, the |
547 | * resources created by eventfs_start_creating() needs to be cleaned up. In |
548 | * that case, this function should be called to perform that clean up. |
549 | */ |
550 | struct dentry *eventfs_failed_creating(struct dentry *dentry) |
551 | { |
552 | dput(dentry); |
553 | simple_release_fs(mount: &tracefs_mount, count: &tracefs_mount_count); |
554 | return NULL; |
555 | } |
556 | |
557 | /** |
558 | * eventfs_end_creating - Finish the process of creating a eventfs dentry |
559 | * @dentry: The dentry that has successfully been created. |
560 | * |
561 | * This function is currently just a place holder to match |
562 | * eventfs_start_creating(). In case any synchronization needs to be added, |
563 | * this function will be used to implement that without having to modify |
564 | * the callers of eventfs_start_creating(). |
565 | */ |
566 | struct dentry *eventfs_end_creating(struct dentry *dentry) |
567 | { |
568 | return dentry; |
569 | } |
570 | |
571 | /** |
572 | * tracefs_create_file - create a file in the tracefs filesystem |
573 | * @name: a pointer to a string containing the name of the file to create. |
574 | * @mode: the permission that the file should have. |
575 | * @parent: a pointer to the parent dentry for this file. This should be a |
576 | * directory dentry if set. If this parameter is NULL, then the |
577 | * file will be created in the root of the tracefs filesystem. |
578 | * @data: a pointer to something that the caller will want to get to later |
579 | * on. The inode.i_private pointer will point to this value on |
580 | * the open() call. |
581 | * @fops: a pointer to a struct file_operations that should be used for |
582 | * this file. |
583 | * |
584 | * This is the basic "create a file" function for tracefs. It allows for a |
585 | * wide range of flexibility in creating a file, or a directory (if you want |
586 | * to create a directory, the tracefs_create_dir() function is |
587 | * recommended to be used instead.) |
588 | * |
589 | * This function will return a pointer to a dentry if it succeeds. This |
590 | * pointer must be passed to the tracefs_remove() function when the file is |
591 | * to be removed (no automatic cleanup happens if your module is unloaded, |
592 | * you are responsible here.) If an error occurs, %NULL will be returned. |
593 | * |
594 | * If tracefs is not enabled in the kernel, the value -%ENODEV will be |
595 | * returned. |
596 | */ |
597 | struct dentry *tracefs_create_file(const char *name, umode_t mode, |
598 | struct dentry *parent, void *data, |
599 | const struct file_operations *fops) |
600 | { |
601 | struct dentry *dentry; |
602 | struct inode *inode; |
603 | |
604 | if (security_locked_down(what: LOCKDOWN_TRACEFS)) |
605 | return NULL; |
606 | |
607 | if (!(mode & S_IFMT)) |
608 | mode |= S_IFREG; |
609 | BUG_ON(!S_ISREG(mode)); |
610 | dentry = tracefs_start_creating(name, parent); |
611 | |
612 | if (IS_ERR(ptr: dentry)) |
613 | return NULL; |
614 | |
615 | inode = tracefs_get_inode(sb: dentry->d_sb); |
616 | if (unlikely(!inode)) |
617 | return tracefs_failed_creating(dentry); |
618 | |
619 | inode->i_mode = mode; |
620 | inode->i_fop = fops ? fops : &tracefs_file_operations; |
621 | inode->i_private = data; |
622 | inode->i_uid = d_inode(dentry: dentry->d_parent)->i_uid; |
623 | inode->i_gid = d_inode(dentry: dentry->d_parent)->i_gid; |
624 | d_instantiate(dentry, inode); |
625 | fsnotify_create(dir: d_inode(dentry: dentry->d_parent), dentry); |
626 | return tracefs_end_creating(dentry); |
627 | } |
628 | |
629 | static struct dentry *__create_dir(const char *name, struct dentry *parent, |
630 | const struct inode_operations *ops) |
631 | { |
632 | struct dentry *dentry = tracefs_start_creating(name, parent); |
633 | struct inode *inode; |
634 | |
635 | if (IS_ERR(ptr: dentry)) |
636 | return NULL; |
637 | |
638 | inode = tracefs_get_inode(sb: dentry->d_sb); |
639 | if (unlikely(!inode)) |
640 | return tracefs_failed_creating(dentry); |
641 | |
642 | /* Do not set bits for OTH */ |
643 | inode->i_mode = S_IFDIR | S_IRWXU | S_IRUSR| S_IRGRP | S_IXUSR | S_IXGRP; |
644 | inode->i_op = ops; |
645 | inode->i_fop = &simple_dir_operations; |
646 | inode->i_uid = d_inode(dentry: dentry->d_parent)->i_uid; |
647 | inode->i_gid = d_inode(dentry: dentry->d_parent)->i_gid; |
648 | |
649 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ |
650 | inc_nlink(inode); |
651 | d_instantiate(dentry, inode); |
652 | inc_nlink(inode: d_inode(dentry: dentry->d_parent)); |
653 | fsnotify_mkdir(dir: d_inode(dentry: dentry->d_parent), dentry); |
654 | return tracefs_end_creating(dentry); |
655 | } |
656 | |
657 | /** |
658 | * tracefs_create_dir - create a directory in the tracefs filesystem |
659 | * @name: a pointer to a string containing the name of the directory to |
660 | * create. |
661 | * @parent: a pointer to the parent dentry for this file. This should be a |
662 | * directory dentry if set. If this parameter is NULL, then the |
663 | * directory will be created in the root of the tracefs filesystem. |
664 | * |
665 | * This function creates a directory in tracefs with the given name. |
666 | * |
667 | * This function will return a pointer to a dentry if it succeeds. This |
668 | * pointer must be passed to the tracefs_remove() function when the file is |
669 | * to be removed. If an error occurs, %NULL will be returned. |
670 | * |
671 | * If tracing is not enabled in the kernel, the value -%ENODEV will be |
672 | * returned. |
673 | */ |
674 | struct dentry *tracefs_create_dir(const char *name, struct dentry *parent) |
675 | { |
676 | if (security_locked_down(what: LOCKDOWN_TRACEFS)) |
677 | return NULL; |
678 | |
679 | return __create_dir(name, parent, ops: &simple_dir_inode_operations); |
680 | } |
681 | |
682 | /** |
683 | * tracefs_create_instance_dir - create the tracing instances directory |
684 | * @name: The name of the instances directory to create |
685 | * @parent: The parent directory that the instances directory will exist |
686 | * @mkdir: The function to call when a mkdir is performed. |
687 | * @rmdir: The function to call when a rmdir is performed. |
688 | * |
689 | * Only one instances directory is allowed. |
690 | * |
691 | * The instances directory is special as it allows for mkdir and rmdir |
692 | * to be done by userspace. When a mkdir or rmdir is performed, the inode |
693 | * locks are released and the methods passed in (@mkdir and @rmdir) are |
694 | * called without locks and with the name of the directory being created |
695 | * within the instances directory. |
696 | * |
697 | * Returns the dentry of the instances directory. |
698 | */ |
699 | __init struct dentry *tracefs_create_instance_dir(const char *name, |
700 | struct dentry *parent, |
701 | int (*mkdir)(const char *name), |
702 | int (*rmdir)(const char *name)) |
703 | { |
704 | struct dentry *dentry; |
705 | |
706 | /* Only allow one instance of the instances directory. */ |
707 | if (WARN_ON(tracefs_ops.mkdir || tracefs_ops.rmdir)) |
708 | return NULL; |
709 | |
710 | dentry = __create_dir(name, parent, ops: &tracefs_dir_inode_operations); |
711 | if (!dentry) |
712 | return NULL; |
713 | |
714 | tracefs_ops.mkdir = mkdir; |
715 | tracefs_ops.rmdir = rmdir; |
716 | |
717 | return dentry; |
718 | } |
719 | |
720 | static void remove_one(struct dentry *victim) |
721 | { |
722 | simple_release_fs(mount: &tracefs_mount, count: &tracefs_mount_count); |
723 | } |
724 | |
725 | /** |
726 | * tracefs_remove - recursively removes a directory |
727 | * @dentry: a pointer to a the dentry of the directory to be removed. |
728 | * |
729 | * This function recursively removes a directory tree in tracefs that |
730 | * was previously created with a call to another tracefs function |
731 | * (like tracefs_create_file() or variants thereof.) |
732 | */ |
733 | void tracefs_remove(struct dentry *dentry) |
734 | { |
735 | if (IS_ERR_OR_NULL(ptr: dentry)) |
736 | return; |
737 | |
738 | simple_pin_fs(&trace_fs_type, mount: &tracefs_mount, count: &tracefs_mount_count); |
739 | simple_recursive_removal(dentry, callback: remove_one); |
740 | simple_release_fs(mount: &tracefs_mount, count: &tracefs_mount_count); |
741 | } |
742 | |
743 | /** |
744 | * tracefs_initialized - Tells whether tracefs has been registered |
745 | */ |
746 | bool tracefs_initialized(void) |
747 | { |
748 | return tracefs_registered; |
749 | } |
750 | |
751 | static void init_once(void *foo) |
752 | { |
753 | struct tracefs_inode *ti = (struct tracefs_inode *) foo; |
754 | |
755 | inode_init_once(&ti->vfs_inode); |
756 | } |
757 | |
758 | static int __init tracefs_init(void) |
759 | { |
760 | int retval; |
761 | |
762 | tracefs_inode_cachep = kmem_cache_create(name: "tracefs_inode_cache" , |
763 | size: sizeof(struct tracefs_inode), |
764 | align: 0, flags: (SLAB_RECLAIM_ACCOUNT| |
765 | SLAB_MEM_SPREAD| |
766 | SLAB_ACCOUNT), |
767 | ctor: init_once); |
768 | if (!tracefs_inode_cachep) |
769 | return -ENOMEM; |
770 | |
771 | retval = sysfs_create_mount_point(parent_kobj: kernel_kobj, name: "tracing" ); |
772 | if (retval) |
773 | return -EINVAL; |
774 | |
775 | retval = register_filesystem(&trace_fs_type); |
776 | if (!retval) |
777 | tracefs_registered = true; |
778 | |
779 | return retval; |
780 | } |
781 | core_initcall(tracefs_init); |
782 | |