blob: d895b4b7b66116f47ef68ed6ef5b3d46d31980ab [file] [log] [blame]
Tejun Heob8441ed2013-11-24 09:54:58 -05001/*
2 * fs/kernfs/file.c - kernfs file implementation
3 *
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
7 *
8 * This file is released under the GPLv2.
9 */
Tejun Heo414985a2013-11-28 14:54:34 -050010
11#include <linux/fs.h>
12#include <linux/seq_file.h>
13#include <linux/slab.h>
14#include <linux/poll.h>
15#include <linux/pagemap.h>
Tejun Heo414985a2013-11-28 14:54:34 -050016#include <linux/sched.h>
Tejun Heod911d982014-04-09 11:07:31 -040017#include <linux/fsnotify.h>
Tejun Heo414985a2013-11-28 14:54:34 -050018
19#include "kernfs-internal.h"
20
21/*
Tejun Heoc525aad2013-12-11 14:11:55 -050022 * There's one kernfs_open_file for each open file and one kernfs_open_node
Tejun Heo324a56e2013-12-11 14:11:53 -050023 * for each kernfs_node with one or more open files.
Tejun Heo414985a2013-11-28 14:54:34 -050024 *
Tejun Heoc525aad2013-12-11 14:11:55 -050025 * kernfs_node->attr.open points to kernfs_open_node. attr.open is
26 * protected by kernfs_open_node_lock.
Tejun Heo414985a2013-11-28 14:54:34 -050027 *
28 * filp->private_data points to seq_file whose ->private points to
Tejun Heoc525aad2013-12-11 14:11:55 -050029 * kernfs_open_file. kernfs_open_files are chained at
30 * kernfs_open_node->files, which is protected by kernfs_open_file_mutex.
Tejun Heo414985a2013-11-28 14:54:34 -050031 */
Tejun Heoc525aad2013-12-11 14:11:55 -050032static DEFINE_SPINLOCK(kernfs_open_node_lock);
33static DEFINE_MUTEX(kernfs_open_file_mutex);
Tejun Heo414985a2013-11-28 14:54:34 -050034
Tejun Heoc525aad2013-12-11 14:11:55 -050035struct kernfs_open_node {
Tejun Heo414985a2013-11-28 14:54:34 -050036 atomic_t refcnt;
37 atomic_t event;
38 wait_queue_head_t poll;
Tejun Heoc525aad2013-12-11 14:11:55 -050039 struct list_head files; /* goes through kernfs_open_file.list */
Tejun Heo414985a2013-11-28 14:54:34 -050040};
41
Tejun Heoecca47c2014-07-01 16:41:03 -040042/*
43 * kernfs_notify() may be called from any context and bounces notifications
44 * through a work item. To minimize space overhead in kernfs_node, the
45 * pending queue is implemented as a singly linked list of kernfs_nodes.
46 * The list is terminated with the self pointer so that whether a
47 * kernfs_node is on the list or not can be determined by testing the next
48 * pointer for NULL.
49 */
50#define KERNFS_NOTIFY_EOL ((void *)&kernfs_notify_list)
51
52static DEFINE_SPINLOCK(kernfs_notify_lock);
53static struct kernfs_node *kernfs_notify_list = KERNFS_NOTIFY_EOL;
54
Tejun Heoc525aad2013-12-11 14:11:55 -050055static struct kernfs_open_file *kernfs_of(struct file *file)
Tejun Heo414985a2013-11-28 14:54:34 -050056{
57 return ((struct seq_file *)file->private_data)->private;
58}
59
60/*
Tejun Heo324a56e2013-12-11 14:11:53 -050061 * Determine the kernfs_ops for the given kernfs_node. This function must
Tejun Heo414985a2013-11-28 14:54:34 -050062 * be called while holding an active reference.
63 */
Tejun Heo324a56e2013-12-11 14:11:53 -050064static const struct kernfs_ops *kernfs_ops(struct kernfs_node *kn)
Tejun Heo414985a2013-11-28 14:54:34 -050065{
Tejun Heodf23fc32013-12-11 14:11:56 -050066 if (kn->flags & KERNFS_LOCKDEP)
Tejun Heo324a56e2013-12-11 14:11:53 -050067 lockdep_assert_held(kn);
Tejun Heoadc5e8b2013-12-11 14:11:54 -050068 return kn->attr.ops;
Tejun Heo414985a2013-11-28 14:54:34 -050069}
70
Tejun Heobb305942014-01-14 09:52:01 -050071/*
72 * As kernfs_seq_stop() is also called after kernfs_seq_start() or
73 * kernfs_seq_next() failure, it needs to distinguish whether it's stopping
74 * a seq_file iteration which is fully initialized with an active reference
75 * or an aborted kernfs_seq_start() due to get_active failure. The
76 * position pointer is the only context for each seq_file iteration and
77 * thus the stop condition should be encoded in it. As the return value is
78 * directly visible to userland, ERR_PTR(-ENODEV) is the only acceptable
79 * choice to indicate get_active failure.
80 *
81 * Unfortunately, this is complicated due to the optional custom seq_file
82 * operations which may return ERR_PTR(-ENODEV) too. kernfs_seq_stop()
83 * can't distinguish whether ERR_PTR(-ENODEV) is from get_active failure or
84 * custom seq_file operations and thus can't decide whether put_active
85 * should be performed or not only on ERR_PTR(-ENODEV).
86 *
87 * This is worked around by factoring out the custom seq_stop() and
88 * put_active part into kernfs_seq_stop_active(), skipping it from
89 * kernfs_seq_stop() if ERR_PTR(-ENODEV) while invoking it directly after
90 * custom seq_file operations fail with ERR_PTR(-ENODEV) - this ensures
91 * that kernfs_seq_stop_active() is skipped only after get_active failure.
92 */
93static void kernfs_seq_stop_active(struct seq_file *sf, void *v)
94{
95 struct kernfs_open_file *of = sf->private;
96 const struct kernfs_ops *ops = kernfs_ops(of->kn);
97
98 if (ops->seq_stop)
99 ops->seq_stop(sf, v);
100 kernfs_put_active(of->kn);
101}
102
Tejun Heo414985a2013-11-28 14:54:34 -0500103static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
104{
Tejun Heoc525aad2013-12-11 14:11:55 -0500105 struct kernfs_open_file *of = sf->private;
Tejun Heo414985a2013-11-28 14:54:34 -0500106 const struct kernfs_ops *ops;
107
108 /*
109 * @of->mutex nests outside active ref and is just to ensure that
110 * the ops aren't called concurrently for the same open file.
111 */
112 mutex_lock(&of->mutex);
Tejun Heoc637b8a2013-12-11 14:11:58 -0500113 if (!kernfs_get_active(of->kn))
Tejun Heo414985a2013-11-28 14:54:34 -0500114 return ERR_PTR(-ENODEV);
115
Tejun Heo324a56e2013-12-11 14:11:53 -0500116 ops = kernfs_ops(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500117 if (ops->seq_start) {
Tejun Heobb305942014-01-14 09:52:01 -0500118 void *next = ops->seq_start(sf, ppos);
119 /* see the comment above kernfs_seq_stop_active() */
120 if (next == ERR_PTR(-ENODEV))
121 kernfs_seq_stop_active(sf, next);
122 return next;
Tejun Heo414985a2013-11-28 14:54:34 -0500123 } else {
124 /*
125 * The same behavior and code as single_open(). Returns
126 * !NULL if pos is at the beginning; otherwise, NULL.
127 */
128 return NULL + !*ppos;
129 }
130}
131
132static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
133{
Tejun Heoc525aad2013-12-11 14:11:55 -0500134 struct kernfs_open_file *of = sf->private;
Tejun Heo324a56e2013-12-11 14:11:53 -0500135 const struct kernfs_ops *ops = kernfs_ops(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500136
137 if (ops->seq_next) {
Tejun Heobb305942014-01-14 09:52:01 -0500138 void *next = ops->seq_next(sf, v, ppos);
139 /* see the comment above kernfs_seq_stop_active() */
140 if (next == ERR_PTR(-ENODEV))
141 kernfs_seq_stop_active(sf, next);
142 return next;
Tejun Heo414985a2013-11-28 14:54:34 -0500143 } else {
144 /*
145 * The same behavior and code as single_open(), always
146 * terminate after the initial read.
147 */
148 ++*ppos;
149 return NULL;
150 }
151}
152
153static void kernfs_seq_stop(struct seq_file *sf, void *v)
154{
Tejun Heoc525aad2013-12-11 14:11:55 -0500155 struct kernfs_open_file *of = sf->private;
Tejun Heo414985a2013-11-28 14:54:34 -0500156
Tejun Heobb305942014-01-14 09:52:01 -0500157 if (v != ERR_PTR(-ENODEV))
158 kernfs_seq_stop_active(sf, v);
Tejun Heo414985a2013-11-28 14:54:34 -0500159 mutex_unlock(&of->mutex);
160}
161
162static int kernfs_seq_show(struct seq_file *sf, void *v)
163{
Tejun Heoc525aad2013-12-11 14:11:55 -0500164 struct kernfs_open_file *of = sf->private;
Tejun Heo414985a2013-11-28 14:54:34 -0500165
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500166 of->event = atomic_read(&of->kn->attr.open->event);
Tejun Heo414985a2013-11-28 14:54:34 -0500167
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500168 return of->kn->attr.ops->seq_show(sf, v);
Tejun Heo414985a2013-11-28 14:54:34 -0500169}
170
171static const struct seq_operations kernfs_seq_ops = {
172 .start = kernfs_seq_start,
173 .next = kernfs_seq_next,
174 .stop = kernfs_seq_stop,
175 .show = kernfs_seq_show,
176};
177
178/*
179 * As reading a bin file can have side-effects, the exact offset and bytes
180 * specified in read(2) call should be passed to the read callback making
181 * it difficult to use seq_file. Implement simplistic custom buffering for
182 * bin files.
183 */
Tejun Heoc525aad2013-12-11 14:11:55 -0500184static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of,
Tejun Heo414985a2013-11-28 14:54:34 -0500185 char __user *user_buf, size_t count,
186 loff_t *ppos)
187{
188 ssize_t len = min_t(size_t, count, PAGE_SIZE);
189 const struct kernfs_ops *ops;
190 char *buf;
191
192 buf = kmalloc(len, GFP_KERNEL);
193 if (!buf)
194 return -ENOMEM;
195
196 /*
197 * @of->mutex nests outside active ref and is just to ensure that
198 * the ops aren't called concurrently for the same open file.
199 */
200 mutex_lock(&of->mutex);
Tejun Heoc637b8a2013-12-11 14:11:58 -0500201 if (!kernfs_get_active(of->kn)) {
Tejun Heo414985a2013-11-28 14:54:34 -0500202 len = -ENODEV;
203 mutex_unlock(&of->mutex);
204 goto out_free;
205 }
206
Tejun Heo324a56e2013-12-11 14:11:53 -0500207 ops = kernfs_ops(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500208 if (ops->read)
209 len = ops->read(of, buf, len, *ppos);
210 else
211 len = -EINVAL;
212
Tejun Heoc637b8a2013-12-11 14:11:58 -0500213 kernfs_put_active(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500214 mutex_unlock(&of->mutex);
215
216 if (len < 0)
217 goto out_free;
218
219 if (copy_to_user(user_buf, buf, len)) {
220 len = -EFAULT;
221 goto out_free;
222 }
223
224 *ppos += len;
225
226 out_free:
227 kfree(buf);
228 return len;
229}
230
231/**
Tejun Heoc637b8a2013-12-11 14:11:58 -0500232 * kernfs_fop_read - kernfs vfs read callback
Tejun Heo414985a2013-11-28 14:54:34 -0500233 * @file: file pointer
234 * @user_buf: data to write
235 * @count: number of bytes
236 * @ppos: starting offset
237 */
Tejun Heoc637b8a2013-12-11 14:11:58 -0500238static ssize_t kernfs_fop_read(struct file *file, char __user *user_buf,
239 size_t count, loff_t *ppos)
Tejun Heo414985a2013-11-28 14:54:34 -0500240{
Tejun Heoc525aad2013-12-11 14:11:55 -0500241 struct kernfs_open_file *of = kernfs_of(file);
Tejun Heo414985a2013-11-28 14:54:34 -0500242
Tejun Heodf23fc32013-12-11 14:11:56 -0500243 if (of->kn->flags & KERNFS_HAS_SEQ_SHOW)
Tejun Heo414985a2013-11-28 14:54:34 -0500244 return seq_read(file, user_buf, count, ppos);
245 else
246 return kernfs_file_direct_read(of, user_buf, count, ppos);
247}
248
249/**
Tejun Heoc637b8a2013-12-11 14:11:58 -0500250 * kernfs_fop_write - kernfs vfs write callback
Tejun Heo414985a2013-11-28 14:54:34 -0500251 * @file: file pointer
252 * @user_buf: data to write
253 * @count: number of bytes
254 * @ppos: starting offset
255 *
256 * Copy data in from userland and pass it to the matching kernfs write
257 * operation.
258 *
259 * There is no easy way for us to know if userspace is only doing a partial
260 * write, so we don't support them. We expect the entire buffer to come on
261 * the first write. Hint: if you're writing a value, first read the file,
262 * modify only the the value you're changing, then write entire buffer
263 * back.
264 */
Tejun Heoc637b8a2013-12-11 14:11:58 -0500265static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf,
266 size_t count, loff_t *ppos)
Tejun Heo414985a2013-11-28 14:54:34 -0500267{
Tejun Heoc525aad2013-12-11 14:11:55 -0500268 struct kernfs_open_file *of = kernfs_of(file);
Tejun Heo414985a2013-11-28 14:54:34 -0500269 const struct kernfs_ops *ops;
Tejun Heob7ce40c2014-03-04 15:38:46 -0500270 size_t len;
271 char *buf;
272
273 if (of->atomic_write_len) {
274 len = count;
275 if (len > of->atomic_write_len)
276 return -E2BIG;
277 } else {
278 len = min_t(size_t, count, PAGE_SIZE);
279 }
280
281 buf = kmalloc(len + 1, GFP_KERNEL);
282 if (!buf)
283 return -ENOMEM;
284
285 if (copy_from_user(buf, user_buf, len)) {
286 len = -EFAULT;
287 goto out_free;
288 }
289 buf[len] = '\0'; /* guarantee string termination */
Tejun Heo414985a2013-11-28 14:54:34 -0500290
291 /*
292 * @of->mutex nests outside active ref and is just to ensure that
293 * the ops aren't called concurrently for the same open file.
294 */
295 mutex_lock(&of->mutex);
Tejun Heoc637b8a2013-12-11 14:11:58 -0500296 if (!kernfs_get_active(of->kn)) {
Tejun Heo414985a2013-11-28 14:54:34 -0500297 mutex_unlock(&of->mutex);
Tejun Heob7ce40c2014-03-04 15:38:46 -0500298 len = -ENODEV;
299 goto out_free;
Tejun Heo414985a2013-11-28 14:54:34 -0500300 }
301
Tejun Heo324a56e2013-12-11 14:11:53 -0500302 ops = kernfs_ops(of->kn);
Tejun Heob7ce40c2014-03-04 15:38:46 -0500303 if (ops->write)
304 len = ops->write(of, buf, len, *ppos);
305 else
Tejun Heo414985a2013-11-28 14:54:34 -0500306 len = -EINVAL;
307
Tejun Heoc637b8a2013-12-11 14:11:58 -0500308 kernfs_put_active(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500309 mutex_unlock(&of->mutex);
310
311 if (len > 0)
312 *ppos += len;
Tejun Heob7ce40c2014-03-04 15:38:46 -0500313out_free:
Tejun Heo414985a2013-11-28 14:54:34 -0500314 kfree(buf);
315 return len;
316}
317
318static void kernfs_vma_open(struct vm_area_struct *vma)
319{
320 struct file *file = vma->vm_file;
Tejun Heoc525aad2013-12-11 14:11:55 -0500321 struct kernfs_open_file *of = kernfs_of(file);
Tejun Heo414985a2013-11-28 14:54:34 -0500322
323 if (!of->vm_ops)
324 return;
325
Tejun Heoc637b8a2013-12-11 14:11:58 -0500326 if (!kernfs_get_active(of->kn))
Tejun Heo414985a2013-11-28 14:54:34 -0500327 return;
328
329 if (of->vm_ops->open)
330 of->vm_ops->open(vma);
331
Tejun Heoc637b8a2013-12-11 14:11:58 -0500332 kernfs_put_active(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500333}
334
335static int kernfs_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
336{
337 struct file *file = vma->vm_file;
Tejun Heoc525aad2013-12-11 14:11:55 -0500338 struct kernfs_open_file *of = kernfs_of(file);
Tejun Heo414985a2013-11-28 14:54:34 -0500339 int ret;
340
341 if (!of->vm_ops)
342 return VM_FAULT_SIGBUS;
343
Tejun Heoc637b8a2013-12-11 14:11:58 -0500344 if (!kernfs_get_active(of->kn))
Tejun Heo414985a2013-11-28 14:54:34 -0500345 return VM_FAULT_SIGBUS;
346
347 ret = VM_FAULT_SIGBUS;
348 if (of->vm_ops->fault)
349 ret = of->vm_ops->fault(vma, vmf);
350
Tejun Heoc637b8a2013-12-11 14:11:58 -0500351 kernfs_put_active(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500352 return ret;
353}
354
355static int kernfs_vma_page_mkwrite(struct vm_area_struct *vma,
356 struct vm_fault *vmf)
357{
358 struct file *file = vma->vm_file;
Tejun Heoc525aad2013-12-11 14:11:55 -0500359 struct kernfs_open_file *of = kernfs_of(file);
Tejun Heo414985a2013-11-28 14:54:34 -0500360 int ret;
361
362 if (!of->vm_ops)
363 return VM_FAULT_SIGBUS;
364
Tejun Heoc637b8a2013-12-11 14:11:58 -0500365 if (!kernfs_get_active(of->kn))
Tejun Heo414985a2013-11-28 14:54:34 -0500366 return VM_FAULT_SIGBUS;
367
368 ret = 0;
369 if (of->vm_ops->page_mkwrite)
370 ret = of->vm_ops->page_mkwrite(vma, vmf);
371 else
372 file_update_time(file);
373
Tejun Heoc637b8a2013-12-11 14:11:58 -0500374 kernfs_put_active(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500375 return ret;
376}
377
378static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr,
379 void *buf, int len, int write)
380{
381 struct file *file = vma->vm_file;
Tejun Heoc525aad2013-12-11 14:11:55 -0500382 struct kernfs_open_file *of = kernfs_of(file);
Tejun Heo414985a2013-11-28 14:54:34 -0500383 int ret;
384
385 if (!of->vm_ops)
386 return -EINVAL;
387
Tejun Heoc637b8a2013-12-11 14:11:58 -0500388 if (!kernfs_get_active(of->kn))
Tejun Heo414985a2013-11-28 14:54:34 -0500389 return -EINVAL;
390
391 ret = -EINVAL;
392 if (of->vm_ops->access)
393 ret = of->vm_ops->access(vma, addr, buf, len, write);
394
Tejun Heoc637b8a2013-12-11 14:11:58 -0500395 kernfs_put_active(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500396 return ret;
397}
398
399#ifdef CONFIG_NUMA
400static int kernfs_vma_set_policy(struct vm_area_struct *vma,
401 struct mempolicy *new)
402{
403 struct file *file = vma->vm_file;
Tejun Heoc525aad2013-12-11 14:11:55 -0500404 struct kernfs_open_file *of = kernfs_of(file);
Tejun Heo414985a2013-11-28 14:54:34 -0500405 int ret;
406
407 if (!of->vm_ops)
408 return 0;
409
Tejun Heoc637b8a2013-12-11 14:11:58 -0500410 if (!kernfs_get_active(of->kn))
Tejun Heo414985a2013-11-28 14:54:34 -0500411 return -EINVAL;
412
413 ret = 0;
414 if (of->vm_ops->set_policy)
415 ret = of->vm_ops->set_policy(vma, new);
416
Tejun Heoc637b8a2013-12-11 14:11:58 -0500417 kernfs_put_active(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500418 return ret;
419}
420
421static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma,
422 unsigned long addr)
423{
424 struct file *file = vma->vm_file;
Tejun Heoc525aad2013-12-11 14:11:55 -0500425 struct kernfs_open_file *of = kernfs_of(file);
Tejun Heo414985a2013-11-28 14:54:34 -0500426 struct mempolicy *pol;
427
428 if (!of->vm_ops)
429 return vma->vm_policy;
430
Tejun Heoc637b8a2013-12-11 14:11:58 -0500431 if (!kernfs_get_active(of->kn))
Tejun Heo414985a2013-11-28 14:54:34 -0500432 return vma->vm_policy;
433
434 pol = vma->vm_policy;
435 if (of->vm_ops->get_policy)
436 pol = of->vm_ops->get_policy(vma, addr);
437
Tejun Heoc637b8a2013-12-11 14:11:58 -0500438 kernfs_put_active(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500439 return pol;
440}
441
442static int kernfs_vma_migrate(struct vm_area_struct *vma,
443 const nodemask_t *from, const nodemask_t *to,
444 unsigned long flags)
445{
446 struct file *file = vma->vm_file;
Tejun Heoc525aad2013-12-11 14:11:55 -0500447 struct kernfs_open_file *of = kernfs_of(file);
Tejun Heo414985a2013-11-28 14:54:34 -0500448 int ret;
449
450 if (!of->vm_ops)
451 return 0;
452
Tejun Heoc637b8a2013-12-11 14:11:58 -0500453 if (!kernfs_get_active(of->kn))
Tejun Heo414985a2013-11-28 14:54:34 -0500454 return 0;
455
456 ret = 0;
457 if (of->vm_ops->migrate)
458 ret = of->vm_ops->migrate(vma, from, to, flags);
459
Tejun Heoc637b8a2013-12-11 14:11:58 -0500460 kernfs_put_active(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500461 return ret;
462}
463#endif
464
465static const struct vm_operations_struct kernfs_vm_ops = {
466 .open = kernfs_vma_open,
467 .fault = kernfs_vma_fault,
468 .page_mkwrite = kernfs_vma_page_mkwrite,
469 .access = kernfs_vma_access,
470#ifdef CONFIG_NUMA
471 .set_policy = kernfs_vma_set_policy,
472 .get_policy = kernfs_vma_get_policy,
473 .migrate = kernfs_vma_migrate,
474#endif
475};
476
Tejun Heoc637b8a2013-12-11 14:11:58 -0500477static int kernfs_fop_mmap(struct file *file, struct vm_area_struct *vma)
Tejun Heo414985a2013-11-28 14:54:34 -0500478{
Tejun Heoc525aad2013-12-11 14:11:55 -0500479 struct kernfs_open_file *of = kernfs_of(file);
Tejun Heo414985a2013-11-28 14:54:34 -0500480 const struct kernfs_ops *ops;
481 int rc;
482
Tejun Heo9b2db6e2013-12-10 09:29:17 -0500483 /*
484 * mmap path and of->mutex are prone to triggering spurious lockdep
485 * warnings and we don't want to add spurious locking dependency
486 * between the two. Check whether mmap is actually implemented
487 * without grabbing @of->mutex by testing HAS_MMAP flag. See the
488 * comment in kernfs_file_open() for more details.
489 */
Tejun Heodf23fc32013-12-11 14:11:56 -0500490 if (!(of->kn->flags & KERNFS_HAS_MMAP))
Tejun Heo9b2db6e2013-12-10 09:29:17 -0500491 return -ENODEV;
492
Tejun Heo414985a2013-11-28 14:54:34 -0500493 mutex_lock(&of->mutex);
494
495 rc = -ENODEV;
Tejun Heoc637b8a2013-12-11 14:11:58 -0500496 if (!kernfs_get_active(of->kn))
Tejun Heo414985a2013-11-28 14:54:34 -0500497 goto out_unlock;
498
Tejun Heo324a56e2013-12-11 14:11:53 -0500499 ops = kernfs_ops(of->kn);
Tejun Heo9b2db6e2013-12-10 09:29:17 -0500500 rc = ops->mmap(of, vma);
Tejun Heob44b2142014-04-20 08:29:21 -0400501 if (rc)
502 goto out_put;
Tejun Heo414985a2013-11-28 14:54:34 -0500503
504 /*
505 * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
506 * to satisfy versions of X which crash if the mmap fails: that
507 * substitutes a new vm_file, and we don't then want bin_vm_ops.
508 */
509 if (vma->vm_file != file)
510 goto out_put;
511
512 rc = -EINVAL;
513 if (of->mmapped && of->vm_ops != vma->vm_ops)
514 goto out_put;
515
516 /*
517 * It is not possible to successfully wrap close.
518 * So error if someone is trying to use close.
519 */
520 rc = -EINVAL;
521 if (vma->vm_ops && vma->vm_ops->close)
522 goto out_put;
523
524 rc = 0;
525 of->mmapped = 1;
526 of->vm_ops = vma->vm_ops;
527 vma->vm_ops = &kernfs_vm_ops;
528out_put:
Tejun Heoc637b8a2013-12-11 14:11:58 -0500529 kernfs_put_active(of->kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500530out_unlock:
531 mutex_unlock(&of->mutex);
532
533 return rc;
534}
535
536/**
Tejun Heoc637b8a2013-12-11 14:11:58 -0500537 * kernfs_get_open_node - get or create kernfs_open_node
Tejun Heo324a56e2013-12-11 14:11:53 -0500538 * @kn: target kernfs_node
Tejun Heoc525aad2013-12-11 14:11:55 -0500539 * @of: kernfs_open_file for this instance of open
Tejun Heo414985a2013-11-28 14:54:34 -0500540 *
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500541 * If @kn->attr.open exists, increment its reference count; otherwise,
542 * create one. @of is chained to the files list.
Tejun Heo414985a2013-11-28 14:54:34 -0500543 *
544 * LOCKING:
545 * Kernel thread context (may sleep).
546 *
547 * RETURNS:
548 * 0 on success, -errno on failure.
549 */
Tejun Heoc637b8a2013-12-11 14:11:58 -0500550static int kernfs_get_open_node(struct kernfs_node *kn,
551 struct kernfs_open_file *of)
Tejun Heo414985a2013-11-28 14:54:34 -0500552{
Tejun Heoc525aad2013-12-11 14:11:55 -0500553 struct kernfs_open_node *on, *new_on = NULL;
Tejun Heo414985a2013-11-28 14:54:34 -0500554
555 retry:
Tejun Heoc525aad2013-12-11 14:11:55 -0500556 mutex_lock(&kernfs_open_file_mutex);
557 spin_lock_irq(&kernfs_open_node_lock);
Tejun Heo414985a2013-11-28 14:54:34 -0500558
Tejun Heoc525aad2013-12-11 14:11:55 -0500559 if (!kn->attr.open && new_on) {
560 kn->attr.open = new_on;
561 new_on = NULL;
Tejun Heo414985a2013-11-28 14:54:34 -0500562 }
563
Tejun Heoc525aad2013-12-11 14:11:55 -0500564 on = kn->attr.open;
565 if (on) {
566 atomic_inc(&on->refcnt);
567 list_add_tail(&of->list, &on->files);
Tejun Heo414985a2013-11-28 14:54:34 -0500568 }
569
Tejun Heoc525aad2013-12-11 14:11:55 -0500570 spin_unlock_irq(&kernfs_open_node_lock);
571 mutex_unlock(&kernfs_open_file_mutex);
Tejun Heo414985a2013-11-28 14:54:34 -0500572
Tejun Heoc525aad2013-12-11 14:11:55 -0500573 if (on) {
574 kfree(new_on);
Tejun Heo414985a2013-11-28 14:54:34 -0500575 return 0;
576 }
577
578 /* not there, initialize a new one and retry */
Tejun Heoc525aad2013-12-11 14:11:55 -0500579 new_on = kmalloc(sizeof(*new_on), GFP_KERNEL);
580 if (!new_on)
Tejun Heo414985a2013-11-28 14:54:34 -0500581 return -ENOMEM;
582
Tejun Heoc525aad2013-12-11 14:11:55 -0500583 atomic_set(&new_on->refcnt, 0);
584 atomic_set(&new_on->event, 1);
585 init_waitqueue_head(&new_on->poll);
586 INIT_LIST_HEAD(&new_on->files);
Tejun Heo414985a2013-11-28 14:54:34 -0500587 goto retry;
588}
589
590/**
Tejun Heoc637b8a2013-12-11 14:11:58 -0500591 * kernfs_put_open_node - put kernfs_open_node
Tejun Heo324a56e2013-12-11 14:11:53 -0500592 * @kn: target kernfs_nodet
Tejun Heoc525aad2013-12-11 14:11:55 -0500593 * @of: associated kernfs_open_file
Tejun Heo414985a2013-11-28 14:54:34 -0500594 *
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500595 * Put @kn->attr.open and unlink @of from the files list. If
Tejun Heo414985a2013-11-28 14:54:34 -0500596 * reference count reaches zero, disassociate and free it.
597 *
598 * LOCKING:
599 * None.
600 */
Tejun Heoc637b8a2013-12-11 14:11:58 -0500601static void kernfs_put_open_node(struct kernfs_node *kn,
602 struct kernfs_open_file *of)
Tejun Heo414985a2013-11-28 14:54:34 -0500603{
Tejun Heoc525aad2013-12-11 14:11:55 -0500604 struct kernfs_open_node *on = kn->attr.open;
Tejun Heo414985a2013-11-28 14:54:34 -0500605 unsigned long flags;
606
Tejun Heoc525aad2013-12-11 14:11:55 -0500607 mutex_lock(&kernfs_open_file_mutex);
608 spin_lock_irqsave(&kernfs_open_node_lock, flags);
Tejun Heo414985a2013-11-28 14:54:34 -0500609
610 if (of)
611 list_del(&of->list);
612
Tejun Heoc525aad2013-12-11 14:11:55 -0500613 if (atomic_dec_and_test(&on->refcnt))
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500614 kn->attr.open = NULL;
Tejun Heo414985a2013-11-28 14:54:34 -0500615 else
Tejun Heoc525aad2013-12-11 14:11:55 -0500616 on = NULL;
Tejun Heo414985a2013-11-28 14:54:34 -0500617
Tejun Heoc525aad2013-12-11 14:11:55 -0500618 spin_unlock_irqrestore(&kernfs_open_node_lock, flags);
619 mutex_unlock(&kernfs_open_file_mutex);
Tejun Heo414985a2013-11-28 14:54:34 -0500620
Tejun Heoc525aad2013-12-11 14:11:55 -0500621 kfree(on);
Tejun Heo414985a2013-11-28 14:54:34 -0500622}
623
Tejun Heoc637b8a2013-12-11 14:11:58 -0500624static int kernfs_fop_open(struct inode *inode, struct file *file)
Tejun Heo414985a2013-11-28 14:54:34 -0500625{
Tejun Heo324a56e2013-12-11 14:11:53 -0500626 struct kernfs_node *kn = file->f_path.dentry->d_fsdata;
Tejun Heo555724a2014-05-12 13:56:27 -0400627 struct kernfs_root *root = kernfs_root(kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500628 const struct kernfs_ops *ops;
Tejun Heoc525aad2013-12-11 14:11:55 -0500629 struct kernfs_open_file *of;
Tejun Heo414985a2013-11-28 14:54:34 -0500630 bool has_read, has_write, has_mmap;
631 int error = -EACCES;
632
Tejun Heoc637b8a2013-12-11 14:11:58 -0500633 if (!kernfs_get_active(kn))
Tejun Heo414985a2013-11-28 14:54:34 -0500634 return -ENODEV;
635
Tejun Heo324a56e2013-12-11 14:11:53 -0500636 ops = kernfs_ops(kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500637
638 has_read = ops->seq_show || ops->read || ops->mmap;
639 has_write = ops->write || ops->mmap;
640 has_mmap = ops->mmap;
641
Tejun Heo555724a2014-05-12 13:56:27 -0400642 /* see the flag definition for details */
643 if (root->flags & KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK) {
644 if ((file->f_mode & FMODE_WRITE) &&
645 (!(inode->i_mode & S_IWUGO) || !has_write))
646 goto err_out;
Tejun Heo414985a2013-11-28 14:54:34 -0500647
Tejun Heo555724a2014-05-12 13:56:27 -0400648 if ((file->f_mode & FMODE_READ) &&
649 (!(inode->i_mode & S_IRUGO) || !has_read))
650 goto err_out;
651 }
Tejun Heo414985a2013-11-28 14:54:34 -0500652
Tejun Heoc525aad2013-12-11 14:11:55 -0500653 /* allocate a kernfs_open_file for the file */
Tejun Heo414985a2013-11-28 14:54:34 -0500654 error = -ENOMEM;
Tejun Heoc525aad2013-12-11 14:11:55 -0500655 of = kzalloc(sizeof(struct kernfs_open_file), GFP_KERNEL);
Tejun Heo414985a2013-11-28 14:54:34 -0500656 if (!of)
657 goto err_out;
658
659 /*
660 * The following is done to give a different lockdep key to
661 * @of->mutex for files which implement mmap. This is a rather
662 * crude way to avoid false positive lockdep warning around
663 * mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and
664 * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under
665 * which mm->mmap_sem nests, while holding @of->mutex. As each
666 * open file has a separate mutex, it's okay as long as those don't
667 * happen on the same file. At this point, we can't easily give
668 * each file a separate locking class. Let's differentiate on
669 * whether the file has mmap or not for now.
Tejun Heo9b2db6e2013-12-10 09:29:17 -0500670 *
671 * Both paths of the branch look the same. They're supposed to
672 * look that way and give @of->mutex different static lockdep keys.
Tejun Heo414985a2013-11-28 14:54:34 -0500673 */
674 if (has_mmap)
675 mutex_init(&of->mutex);
676 else
677 mutex_init(&of->mutex);
678
Tejun Heo324a56e2013-12-11 14:11:53 -0500679 of->kn = kn;
Tejun Heo414985a2013-11-28 14:54:34 -0500680 of->file = file;
681
682 /*
Tejun Heob7ce40c2014-03-04 15:38:46 -0500683 * Write path needs to atomic_write_len outside active reference.
684 * Cache it in open_file. See kernfs_fop_write() for details.
685 */
686 of->atomic_write_len = ops->atomic_write_len;
687
688 /*
Tejun Heo414985a2013-11-28 14:54:34 -0500689 * Always instantiate seq_file even if read access doesn't use
690 * seq_file or is not requested. This unifies private data access
691 * and readable regular files are the vast majority anyway.
692 */
693 if (ops->seq_show)
694 error = seq_open(file, &kernfs_seq_ops);
695 else
696 error = seq_open(file, NULL);
697 if (error)
698 goto err_free;
699
700 ((struct seq_file *)file->private_data)->private = of;
701
702 /* seq_file clears PWRITE unconditionally, restore it if WRITE */
703 if (file->f_mode & FMODE_WRITE)
704 file->f_mode |= FMODE_PWRITE;
705
Tejun Heoc637b8a2013-12-11 14:11:58 -0500706 /* make sure we have open node struct */
707 error = kernfs_get_open_node(kn, of);
Tejun Heo414985a2013-11-28 14:54:34 -0500708 if (error)
709 goto err_close;
710
711 /* open succeeded, put active references */
Tejun Heoc637b8a2013-12-11 14:11:58 -0500712 kernfs_put_active(kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500713 return 0;
714
715err_close:
716 seq_release(inode, file);
717err_free:
718 kfree(of);
719err_out:
Tejun Heoc637b8a2013-12-11 14:11:58 -0500720 kernfs_put_active(kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500721 return error;
722}
723
Tejun Heoc637b8a2013-12-11 14:11:58 -0500724static int kernfs_fop_release(struct inode *inode, struct file *filp)
Tejun Heo414985a2013-11-28 14:54:34 -0500725{
Tejun Heo324a56e2013-12-11 14:11:53 -0500726 struct kernfs_node *kn = filp->f_path.dentry->d_fsdata;
Tejun Heoc525aad2013-12-11 14:11:55 -0500727 struct kernfs_open_file *of = kernfs_of(filp);
Tejun Heo414985a2013-11-28 14:54:34 -0500728
Tejun Heoc637b8a2013-12-11 14:11:58 -0500729 kernfs_put_open_node(kn, of);
Tejun Heo414985a2013-11-28 14:54:34 -0500730 seq_release(inode, filp);
731 kfree(of);
732
733 return 0;
734}
735
Greg Kroah-Hartman55f6e302014-01-13 14:27:16 -0800736void kernfs_unmap_bin_file(struct kernfs_node *kn)
Tejun Heo414985a2013-11-28 14:54:34 -0500737{
Tejun Heoc525aad2013-12-11 14:11:55 -0500738 struct kernfs_open_node *on;
739 struct kernfs_open_file *of;
Tejun Heo414985a2013-11-28 14:54:34 -0500740
Greg Kroah-Hartman55f6e302014-01-13 14:27:16 -0800741 if (!(kn->flags & KERNFS_HAS_MMAP))
742 return;
743
Tejun Heoc525aad2013-12-11 14:11:55 -0500744 spin_lock_irq(&kernfs_open_node_lock);
745 on = kn->attr.open;
746 if (on)
747 atomic_inc(&on->refcnt);
748 spin_unlock_irq(&kernfs_open_node_lock);
749 if (!on)
Tejun Heo414985a2013-11-28 14:54:34 -0500750 return;
751
Tejun Heoc525aad2013-12-11 14:11:55 -0500752 mutex_lock(&kernfs_open_file_mutex);
753 list_for_each_entry(of, &on->files, list) {
Tejun Heo414985a2013-11-28 14:54:34 -0500754 struct inode *inode = file_inode(of->file);
755 unmap_mapping_range(inode->i_mapping, 0, 0, 1);
756 }
Tejun Heoc525aad2013-12-11 14:11:55 -0500757 mutex_unlock(&kernfs_open_file_mutex);
Tejun Heo414985a2013-11-28 14:54:34 -0500758
Tejun Heoc637b8a2013-12-11 14:11:58 -0500759 kernfs_put_open_node(kn, NULL);
Tejun Heo414985a2013-11-28 14:54:34 -0500760}
761
Tejun Heoc637b8a2013-12-11 14:11:58 -0500762/*
763 * Kernfs attribute files are pollable. The idea is that you read
Tejun Heo414985a2013-11-28 14:54:34 -0500764 * the content and then you use 'poll' or 'select' to wait for
765 * the content to change. When the content changes (assuming the
766 * manager for the kobject supports notification), poll will
767 * return POLLERR|POLLPRI, and select will return the fd whether
768 * it is waiting for read, write, or exceptions.
769 * Once poll/select indicates that the value has changed, you
770 * need to close and re-open the file, or seek to 0 and read again.
771 * Reminder: this only works for attributes which actively support
772 * it, and it is not possible to test an attribute from userspace
773 * to see if it supports poll (Neither 'poll' nor 'select' return
774 * an appropriate error code). When in doubt, set a suitable timeout value.
775 */
Tejun Heoc637b8a2013-12-11 14:11:58 -0500776static unsigned int kernfs_fop_poll(struct file *filp, poll_table *wait)
Tejun Heo414985a2013-11-28 14:54:34 -0500777{
Tejun Heoc525aad2013-12-11 14:11:55 -0500778 struct kernfs_open_file *of = kernfs_of(filp);
Tejun Heo324a56e2013-12-11 14:11:53 -0500779 struct kernfs_node *kn = filp->f_path.dentry->d_fsdata;
Tejun Heoc525aad2013-12-11 14:11:55 -0500780 struct kernfs_open_node *on = kn->attr.open;
Tejun Heo414985a2013-11-28 14:54:34 -0500781
782 /* need parent for the kobj, grab both */
Tejun Heoc637b8a2013-12-11 14:11:58 -0500783 if (!kernfs_get_active(kn))
Tejun Heo414985a2013-11-28 14:54:34 -0500784 goto trigger;
785
Tejun Heoc525aad2013-12-11 14:11:55 -0500786 poll_wait(filp, &on->poll, wait);
Tejun Heo414985a2013-11-28 14:54:34 -0500787
Tejun Heoc637b8a2013-12-11 14:11:58 -0500788 kernfs_put_active(kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500789
Tejun Heoc525aad2013-12-11 14:11:55 -0500790 if (of->event != atomic_read(&on->event))
Tejun Heo414985a2013-11-28 14:54:34 -0500791 goto trigger;
792
793 return DEFAULT_POLLMASK;
794
795 trigger:
796 return DEFAULT_POLLMASK|POLLERR|POLLPRI;
797}
798
Tejun Heoecca47c2014-07-01 16:41:03 -0400799static void kernfs_notify_workfn(struct work_struct *work)
Tejun Heo414985a2013-11-28 14:54:34 -0500800{
Tejun Heoecca47c2014-07-01 16:41:03 -0400801 struct kernfs_node *kn;
Tejun Heoc525aad2013-12-11 14:11:55 -0500802 struct kernfs_open_node *on;
Tejun Heod911d982014-04-09 11:07:31 -0400803 struct kernfs_super_info *info;
Tejun Heoecca47c2014-07-01 16:41:03 -0400804repeat:
805 /* pop one off the notify_list */
806 spin_lock_irq(&kernfs_notify_lock);
807 kn = kernfs_notify_list;
808 if (kn == KERNFS_NOTIFY_EOL) {
809 spin_unlock_irq(&kernfs_notify_lock);
Tejun Heod911d982014-04-09 11:07:31 -0400810 return;
Tejun Heoecca47c2014-07-01 16:41:03 -0400811 }
812 kernfs_notify_list = kn->attr.notify_next;
813 kn->attr.notify_next = NULL;
814 spin_unlock_irq(&kernfs_notify_lock);
Tejun Heod911d982014-04-09 11:07:31 -0400815
816 /* kick poll */
Tejun Heoecca47c2014-07-01 16:41:03 -0400817 spin_lock_irq(&kernfs_open_node_lock);
Tejun Heo414985a2013-11-28 14:54:34 -0500818
Tejun Heod911d982014-04-09 11:07:31 -0400819 on = kn->attr.open;
820 if (on) {
821 atomic_inc(&on->event);
822 wake_up_interruptible(&on->poll);
Tejun Heo414985a2013-11-28 14:54:34 -0500823 }
824
Tejun Heoecca47c2014-07-01 16:41:03 -0400825 spin_unlock_irq(&kernfs_open_node_lock);
Tejun Heod911d982014-04-09 11:07:31 -0400826
827 /* kick fsnotify */
828 mutex_lock(&kernfs_mutex);
829
Tejun Heoecca47c2014-07-01 16:41:03 -0400830 list_for_each_entry(info, &kernfs_root(kn)->supers, node) {
Tejun Heod911d982014-04-09 11:07:31 -0400831 struct inode *inode;
832 struct dentry *dentry;
833
834 inode = ilookup(info->sb, kn->ino);
835 if (!inode)
836 continue;
837
838 dentry = d_find_any_alias(inode);
839 if (dentry) {
840 fsnotify_parent(NULL, dentry, FS_MODIFY);
841 fsnotify(inode, FS_MODIFY, inode, FSNOTIFY_EVENT_INODE,
842 NULL, 0);
843 dput(dentry);
844 }
845
846 iput(inode);
847 }
848
849 mutex_unlock(&kernfs_mutex);
Tejun Heoecca47c2014-07-01 16:41:03 -0400850 kernfs_put(kn);
851 goto repeat;
852}
853
854/**
855 * kernfs_notify - notify a kernfs file
856 * @kn: file to notify
857 *
858 * Notify @kn such that poll(2) on @kn wakes up. Maybe be called from any
859 * context.
860 */
861void kernfs_notify(struct kernfs_node *kn)
862{
863 static DECLARE_WORK(kernfs_notify_work, kernfs_notify_workfn);
864 unsigned long flags;
865
866 if (WARN_ON(kernfs_type(kn) != KERNFS_FILE))
867 return;
868
869 spin_lock_irqsave(&kernfs_notify_lock, flags);
870 if (!kn->attr.notify_next) {
871 kernfs_get(kn);
872 kn->attr.notify_next = kernfs_notify_list;
873 kernfs_notify_list = kn;
874 schedule_work(&kernfs_notify_work);
875 }
876 spin_unlock_irqrestore(&kernfs_notify_lock, flags);
Tejun Heo414985a2013-11-28 14:54:34 -0500877}
878EXPORT_SYMBOL_GPL(kernfs_notify);
879
Tejun Heoa797bfc2013-12-11 14:11:57 -0500880const struct file_operations kernfs_file_fops = {
Tejun Heoc637b8a2013-12-11 14:11:58 -0500881 .read = kernfs_fop_read,
882 .write = kernfs_fop_write,
Tejun Heo414985a2013-11-28 14:54:34 -0500883 .llseek = generic_file_llseek,
Tejun Heoc637b8a2013-12-11 14:11:58 -0500884 .mmap = kernfs_fop_mmap,
885 .open = kernfs_fop_open,
886 .release = kernfs_fop_release,
887 .poll = kernfs_fop_poll,
Tejun Heo414985a2013-11-28 14:54:34 -0500888};
889
890/**
Tejun Heo2063d602013-12-11 16:02:57 -0500891 * __kernfs_create_file - kernfs internal function to create a file
Tejun Heo414985a2013-11-28 14:54:34 -0500892 * @parent: directory to create the file in
893 * @name: name of the file
894 * @mode: mode of the file
895 * @size: size of the file
896 * @ops: kernfs operations for the file
897 * @priv: private data for the file
898 * @ns: optional namespace tag of the file
Tejun Heo2063d602013-12-11 16:02:57 -0500899 * @static_name: don't copy file name
Tejun Heo414985a2013-11-28 14:54:34 -0500900 * @key: lockdep key for the file's active_ref, %NULL to disable lockdep
901 *
902 * Returns the created node on success, ERR_PTR() value on error.
903 */
Tejun Heo2063d602013-12-11 16:02:57 -0500904struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
905 const char *name,
906 umode_t mode, loff_t size,
907 const struct kernfs_ops *ops,
908 void *priv, const void *ns,
909 bool name_is_static,
910 struct lock_class_key *key)
Tejun Heo414985a2013-11-28 14:54:34 -0500911{
Tejun Heo324a56e2013-12-11 14:11:53 -0500912 struct kernfs_node *kn;
Tejun Heo2063d602013-12-11 16:02:57 -0500913 unsigned flags;
Tejun Heo414985a2013-11-28 14:54:34 -0500914 int rc;
915
Tejun Heo2063d602013-12-11 16:02:57 -0500916 flags = KERNFS_FILE;
917 if (name_is_static)
918 flags |= KERNFS_STATIC_NAME;
919
Tejun Heodb4aad22014-01-17 09:58:25 -0500920 kn = kernfs_new_node(parent, name, (mode & S_IALLUGO) | S_IFREG, flags);
Tejun Heo324a56e2013-12-11 14:11:53 -0500921 if (!kn)
Tejun Heo414985a2013-11-28 14:54:34 -0500922 return ERR_PTR(-ENOMEM);
923
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500924 kn->attr.ops = ops;
925 kn->attr.size = size;
926 kn->ns = ns;
Tejun Heo324a56e2013-12-11 14:11:53 -0500927 kn->priv = priv;
Tejun Heo414985a2013-11-28 14:54:34 -0500928
929#ifdef CONFIG_DEBUG_LOCK_ALLOC
930 if (key) {
Tejun Heo324a56e2013-12-11 14:11:53 -0500931 lockdep_init_map(&kn->dep_map, "s_active", key, 0);
Tejun Heodf23fc32013-12-11 14:11:56 -0500932 kn->flags |= KERNFS_LOCKDEP;
Tejun Heo414985a2013-11-28 14:54:34 -0500933 }
934#endif
935
936 /*
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500937 * kn->attr.ops is accesible only while holding active ref. We
Tejun Heo414985a2013-11-28 14:54:34 -0500938 * need to know whether some ops are implemented outside active
939 * ref. Cache their existence in flags.
940 */
941 if (ops->seq_show)
Tejun Heodf23fc32013-12-11 14:11:56 -0500942 kn->flags |= KERNFS_HAS_SEQ_SHOW;
Tejun Heo414985a2013-11-28 14:54:34 -0500943 if (ops->mmap)
Tejun Heodf23fc32013-12-11 14:11:56 -0500944 kn->flags |= KERNFS_HAS_MMAP;
Tejun Heo414985a2013-11-28 14:54:34 -0500945
Tejun Heo988cd7a2014-02-03 14:02:58 -0500946 rc = kernfs_add_one(kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500947 if (rc) {
Tejun Heo324a56e2013-12-11 14:11:53 -0500948 kernfs_put(kn);
Tejun Heo414985a2013-11-28 14:54:34 -0500949 return ERR_PTR(rc);
950 }
Tejun Heo324a56e2013-12-11 14:11:53 -0500951 return kn;
Tejun Heo414985a2013-11-28 14:54:34 -0500952}