2 * fs/kernfs/file.c - kernfs file implementation
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>
8 * This file is released under the GPLv2.
12 #include <linux/seq_file.h>
13 #include <linux/slab.h>
14 #include <linux/poll.h>
15 #include <linux/pagemap.h>
16 #include <linux/sched.h>
17 #include <linux/fsnotify.h>
19 #include "kernfs-internal.h"
22 * There's one kernfs_open_file for each open file and one kernfs_open_node
23 * for each kernfs_node with one or more open files.
25 * kernfs_node->attr.open points to kernfs_open_node. attr.open is
26 * protected by kernfs_open_node_lock.
28 * filp->private_data points to seq_file whose ->private points to
29 * kernfs_open_file. kernfs_open_files are chained at
30 * kernfs_open_node->files, which is protected by kernfs_open_file_mutex.
32 static DEFINE_SPINLOCK(kernfs_open_node_lock
);
33 static DEFINE_MUTEX(kernfs_open_file_mutex
);
35 struct kernfs_open_node
{
38 wait_queue_head_t poll
;
39 struct list_head files
; /* goes through kernfs_open_file.list */
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
50 #define KERNFS_NOTIFY_EOL ((void *)&kernfs_notify_list)
52 static DEFINE_SPINLOCK(kernfs_notify_lock
);
53 static struct kernfs_node
*kernfs_notify_list
= KERNFS_NOTIFY_EOL
;
55 static struct kernfs_open_file
*kernfs_of(struct file
*file
)
57 return ((struct seq_file
*)file
->private_data
)->private;
61 * Determine the kernfs_ops for the given kernfs_node. This function must
62 * be called while holding an active reference.
64 static const struct kernfs_ops
*kernfs_ops(struct kernfs_node
*kn
)
66 if (kn
->flags
& KERNFS_LOCKDEP
)
67 lockdep_assert_held(kn
);
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.
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).
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.
93 static void kernfs_seq_stop_active(struct seq_file
*sf
, void *v
)
95 struct kernfs_open_file
*of
= sf
->private;
96 const struct kernfs_ops
*ops
= kernfs_ops(of
->kn
);
100 kernfs_put_active(of
->kn
);
103 static void *kernfs_seq_start(struct seq_file
*sf
, loff_t
*ppos
)
105 struct kernfs_open_file
*of
= sf
->private;
106 const struct kernfs_ops
*ops
;
109 * @of->mutex nests outside active ref and is primarily to ensure that
110 * the ops aren't called concurrently for the same open file.
112 mutex_lock(&of
->mutex
);
113 if (!kernfs_get_active(of
->kn
))
114 return ERR_PTR(-ENODEV
);
116 ops
= kernfs_ops(of
->kn
);
117 if (ops
->seq_start
) {
118 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
);
125 * The same behavior and code as single_open(). Returns
126 * !NULL if pos is at the beginning; otherwise, NULL.
128 return NULL
+ !*ppos
;
132 static void *kernfs_seq_next(struct seq_file
*sf
, void *v
, loff_t
*ppos
)
134 struct kernfs_open_file
*of
= sf
->private;
135 const struct kernfs_ops
*ops
= kernfs_ops(of
->kn
);
138 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
);
145 * The same behavior and code as single_open(), always
146 * terminate after the initial read.
153 static void kernfs_seq_stop(struct seq_file
*sf
, void *v
)
155 struct kernfs_open_file
*of
= sf
->private;
157 if (v
!= ERR_PTR(-ENODEV
))
158 kernfs_seq_stop_active(sf
, v
);
159 mutex_unlock(&of
->mutex
);
162 static int kernfs_seq_show(struct seq_file
*sf
, void *v
)
164 struct kernfs_open_file
*of
= sf
->private;
166 of
->event
= atomic_read(&of
->kn
->attr
.open
->event
);
168 return of
->kn
->attr
.ops
->seq_show(sf
, v
);
171 static 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
,
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
184 static ssize_t
kernfs_file_direct_read(struct kernfs_open_file
*of
,
185 char __user
*user_buf
, size_t count
,
188 ssize_t len
= min_t(size_t, count
, PAGE_SIZE
);
189 const struct kernfs_ops
*ops
;
192 buf
= of
->prealloc_buf
;
194 buf
= kmalloc(len
, GFP_KERNEL
);
199 * @of->mutex nests outside active ref and is used both to ensure that
200 * the ops aren't called concurrently for the same open file, and
201 * to provide exclusive access to ->prealloc_buf (when that exists).
203 mutex_lock(&of
->mutex
);
204 if (!kernfs_get_active(of
->kn
)) {
206 mutex_unlock(&of
->mutex
);
210 ops
= kernfs_ops(of
->kn
);
212 len
= ops
->read(of
, buf
, len
, *ppos
);
219 if (copy_to_user(user_buf
, buf
, len
)) {
227 kernfs_put_active(of
->kn
);
228 mutex_unlock(&of
->mutex
);
230 if (buf
!= of
->prealloc_buf
)
236 * kernfs_fop_read - kernfs vfs read callback
237 * @file: file pointer
238 * @user_buf: data to write
239 * @count: number of bytes
240 * @ppos: starting offset
242 static ssize_t
kernfs_fop_read(struct file
*file
, char __user
*user_buf
,
243 size_t count
, loff_t
*ppos
)
245 struct kernfs_open_file
*of
= kernfs_of(file
);
247 if (of
->kn
->flags
& KERNFS_HAS_SEQ_SHOW
)
248 return seq_read(file
, user_buf
, count
, ppos
);
250 return kernfs_file_direct_read(of
, user_buf
, count
, ppos
);
254 * kernfs_fop_write - kernfs vfs write callback
255 * @file: file pointer
256 * @user_buf: data to write
257 * @count: number of bytes
258 * @ppos: starting offset
260 * Copy data in from userland and pass it to the matching kernfs write
263 * There is no easy way for us to know if userspace is only doing a partial
264 * write, so we don't support them. We expect the entire buffer to come on
265 * the first write. Hint: if you're writing a value, first read the file,
266 * modify only the the value you're changing, then write entire buffer
269 static ssize_t
kernfs_fop_write(struct file
*file
, const char __user
*user_buf
,
270 size_t count
, loff_t
*ppos
)
272 struct kernfs_open_file
*of
= kernfs_of(file
);
273 const struct kernfs_ops
*ops
;
277 if (of
->atomic_write_len
) {
279 if (len
> of
->atomic_write_len
)
282 len
= min_t(size_t, count
, PAGE_SIZE
);
285 buf
= of
->prealloc_buf
;
287 buf
= kmalloc(len
+ 1, GFP_KERNEL
);
292 * @of->mutex nests outside active ref and is used both to ensure that
293 * the ops aren't called concurrently for the same open file, and
294 * to provide exclusive access to ->prealloc_buf (when that exists).
296 mutex_lock(&of
->mutex
);
297 if (!kernfs_get_active(of
->kn
)) {
298 mutex_unlock(&of
->mutex
);
303 if (copy_from_user(buf
, user_buf
, len
)) {
307 buf
[len
] = '\0'; /* guarantee string termination */
309 ops
= kernfs_ops(of
->kn
);
311 len
= ops
->write(of
, buf
, len
, *ppos
);
319 kernfs_put_active(of
->kn
);
320 mutex_unlock(&of
->mutex
);
322 if (buf
!= of
->prealloc_buf
)
327 static void kernfs_vma_open(struct vm_area_struct
*vma
)
329 struct file
*file
= vma
->vm_file
;
330 struct kernfs_open_file
*of
= kernfs_of(file
);
335 if (!kernfs_get_active(of
->kn
))
338 if (of
->vm_ops
->open
)
339 of
->vm_ops
->open(vma
);
341 kernfs_put_active(of
->kn
);
344 static int kernfs_vma_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
346 struct file
*file
= vma
->vm_file
;
347 struct kernfs_open_file
*of
= kernfs_of(file
);
351 return VM_FAULT_SIGBUS
;
353 if (!kernfs_get_active(of
->kn
))
354 return VM_FAULT_SIGBUS
;
356 ret
= VM_FAULT_SIGBUS
;
357 if (of
->vm_ops
->fault
)
358 ret
= of
->vm_ops
->fault(vma
, vmf
);
360 kernfs_put_active(of
->kn
);
364 static int kernfs_vma_page_mkwrite(struct vm_area_struct
*vma
,
365 struct vm_fault
*vmf
)
367 struct file
*file
= vma
->vm_file
;
368 struct kernfs_open_file
*of
= kernfs_of(file
);
372 return VM_FAULT_SIGBUS
;
374 if (!kernfs_get_active(of
->kn
))
375 return VM_FAULT_SIGBUS
;
378 if (of
->vm_ops
->page_mkwrite
)
379 ret
= of
->vm_ops
->page_mkwrite(vma
, vmf
);
381 file_update_time(file
);
383 kernfs_put_active(of
->kn
);
387 static int kernfs_vma_access(struct vm_area_struct
*vma
, unsigned long addr
,
388 void *buf
, int len
, int write
)
390 struct file
*file
= vma
->vm_file
;
391 struct kernfs_open_file
*of
= kernfs_of(file
);
397 if (!kernfs_get_active(of
->kn
))
401 if (of
->vm_ops
->access
)
402 ret
= of
->vm_ops
->access(vma
, addr
, buf
, len
, write
);
404 kernfs_put_active(of
->kn
);
409 static int kernfs_vma_set_policy(struct vm_area_struct
*vma
,
410 struct mempolicy
*new)
412 struct file
*file
= vma
->vm_file
;
413 struct kernfs_open_file
*of
= kernfs_of(file
);
419 if (!kernfs_get_active(of
->kn
))
423 if (of
->vm_ops
->set_policy
)
424 ret
= of
->vm_ops
->set_policy(vma
, new);
426 kernfs_put_active(of
->kn
);
430 static struct mempolicy
*kernfs_vma_get_policy(struct vm_area_struct
*vma
,
433 struct file
*file
= vma
->vm_file
;
434 struct kernfs_open_file
*of
= kernfs_of(file
);
435 struct mempolicy
*pol
;
438 return vma
->vm_policy
;
440 if (!kernfs_get_active(of
->kn
))
441 return vma
->vm_policy
;
443 pol
= vma
->vm_policy
;
444 if (of
->vm_ops
->get_policy
)
445 pol
= of
->vm_ops
->get_policy(vma
, addr
);
447 kernfs_put_active(of
->kn
);
451 static int kernfs_vma_migrate(struct vm_area_struct
*vma
,
452 const nodemask_t
*from
, const nodemask_t
*to
,
455 struct file
*file
= vma
->vm_file
;
456 struct kernfs_open_file
*of
= kernfs_of(file
);
462 if (!kernfs_get_active(of
->kn
))
466 if (of
->vm_ops
->migrate
)
467 ret
= of
->vm_ops
->migrate(vma
, from
, to
, flags
);
469 kernfs_put_active(of
->kn
);
474 static const struct vm_operations_struct kernfs_vm_ops
= {
475 .open
= kernfs_vma_open
,
476 .fault
= kernfs_vma_fault
,
477 .page_mkwrite
= kernfs_vma_page_mkwrite
,
478 .access
= kernfs_vma_access
,
480 .set_policy
= kernfs_vma_set_policy
,
481 .get_policy
= kernfs_vma_get_policy
,
482 .migrate
= kernfs_vma_migrate
,
486 static int kernfs_fop_mmap(struct file
*file
, struct vm_area_struct
*vma
)
488 struct kernfs_open_file
*of
= kernfs_of(file
);
489 const struct kernfs_ops
*ops
;
493 * mmap path and of->mutex are prone to triggering spurious lockdep
494 * warnings and we don't want to add spurious locking dependency
495 * between the two. Check whether mmap is actually implemented
496 * without grabbing @of->mutex by testing HAS_MMAP flag. See the
497 * comment in kernfs_file_open() for more details.
499 if (!(of
->kn
->flags
& KERNFS_HAS_MMAP
))
502 mutex_lock(&of
->mutex
);
505 if (!kernfs_get_active(of
->kn
))
508 ops
= kernfs_ops(of
->kn
);
509 rc
= ops
->mmap(of
, vma
);
514 * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
515 * to satisfy versions of X which crash if the mmap fails: that
516 * substitutes a new vm_file, and we don't then want bin_vm_ops.
518 if (vma
->vm_file
!= file
)
522 if (of
->mmapped
&& of
->vm_ops
!= vma
->vm_ops
)
526 * It is not possible to successfully wrap close.
527 * So error if someone is trying to use close.
530 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
535 of
->vm_ops
= vma
->vm_ops
;
536 vma
->vm_ops
= &kernfs_vm_ops
;
538 kernfs_put_active(of
->kn
);
540 mutex_unlock(&of
->mutex
);
546 * kernfs_get_open_node - get or create kernfs_open_node
547 * @kn: target kernfs_node
548 * @of: kernfs_open_file for this instance of open
550 * If @kn->attr.open exists, increment its reference count; otherwise,
551 * create one. @of is chained to the files list.
554 * Kernel thread context (may sleep).
557 * 0 on success, -errno on failure.
559 static int kernfs_get_open_node(struct kernfs_node
*kn
,
560 struct kernfs_open_file
*of
)
562 struct kernfs_open_node
*on
, *new_on
= NULL
;
565 mutex_lock(&kernfs_open_file_mutex
);
566 spin_lock_irq(&kernfs_open_node_lock
);
568 if (!kn
->attr
.open
&& new_on
) {
569 kn
->attr
.open
= new_on
;
575 atomic_inc(&on
->refcnt
);
576 list_add_tail(&of
->list
, &on
->files
);
579 spin_unlock_irq(&kernfs_open_node_lock
);
580 mutex_unlock(&kernfs_open_file_mutex
);
587 /* not there, initialize a new one and retry */
588 new_on
= kmalloc(sizeof(*new_on
), GFP_KERNEL
);
592 atomic_set(&new_on
->refcnt
, 0);
593 atomic_set(&new_on
->event
, 1);
594 init_waitqueue_head(&new_on
->poll
);
595 INIT_LIST_HEAD(&new_on
->files
);
600 * kernfs_put_open_node - put kernfs_open_node
601 * @kn: target kernfs_nodet
602 * @of: associated kernfs_open_file
604 * Put @kn->attr.open and unlink @of from the files list. If
605 * reference count reaches zero, disassociate and free it.
610 static void kernfs_put_open_node(struct kernfs_node
*kn
,
611 struct kernfs_open_file
*of
)
613 struct kernfs_open_node
*on
= kn
->attr
.open
;
616 mutex_lock(&kernfs_open_file_mutex
);
617 spin_lock_irqsave(&kernfs_open_node_lock
, flags
);
622 if (atomic_dec_and_test(&on
->refcnt
))
623 kn
->attr
.open
= NULL
;
627 spin_unlock_irqrestore(&kernfs_open_node_lock
, flags
);
628 mutex_unlock(&kernfs_open_file_mutex
);
633 static int kernfs_fop_open(struct inode
*inode
, struct file
*file
)
635 struct kernfs_node
*kn
= file
->f_path
.dentry
->d_fsdata
;
636 struct kernfs_root
*root
= kernfs_root(kn
);
637 const struct kernfs_ops
*ops
;
638 struct kernfs_open_file
*of
;
639 bool has_read
, has_write
, has_mmap
;
642 if (!kernfs_get_active(kn
))
645 ops
= kernfs_ops(kn
);
647 has_read
= ops
->seq_show
|| ops
->read
|| ops
->mmap
;
648 has_write
= ops
->write
|| ops
->mmap
;
649 has_mmap
= ops
->mmap
;
651 /* see the flag definition for details */
652 if (root
->flags
& KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK
) {
653 if ((file
->f_mode
& FMODE_WRITE
) &&
654 (!(inode
->i_mode
& S_IWUGO
) || !has_write
))
657 if ((file
->f_mode
& FMODE_READ
) &&
658 (!(inode
->i_mode
& S_IRUGO
) || !has_read
))
662 /* allocate a kernfs_open_file for the file */
664 of
= kzalloc(sizeof(struct kernfs_open_file
), GFP_KERNEL
);
669 * The following is done to give a different lockdep key to
670 * @of->mutex for files which implement mmap. This is a rather
671 * crude way to avoid false positive lockdep warning around
672 * mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and
673 * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under
674 * which mm->mmap_sem nests, while holding @of->mutex. As each
675 * open file has a separate mutex, it's okay as long as those don't
676 * happen on the same file. At this point, we can't easily give
677 * each file a separate locking class. Let's differentiate on
678 * whether the file has mmap or not for now.
680 * Both paths of the branch look the same. They're supposed to
681 * look that way and give @of->mutex different static lockdep keys.
684 mutex_init(&of
->mutex
);
686 mutex_init(&of
->mutex
);
692 * Write path needs to atomic_write_len outside active reference.
693 * Cache it in open_file. See kernfs_fop_write() for details.
695 of
->atomic_write_len
= ops
->atomic_write_len
;
699 * ->seq_show is incompatible with ->prealloc,
700 * as seq_read does its own allocation.
701 * ->read must be used instead.
703 if (ops
->prealloc
&& ops
->seq_show
)
706 int len
= of
->atomic_write_len
?: PAGE_SIZE
;
707 of
->prealloc_buf
= kmalloc(len
+ 1, GFP_KERNEL
);
709 if (!of
->prealloc_buf
)
714 * Always instantiate seq_file even if read access doesn't use
715 * seq_file or is not requested. This unifies private data access
716 * and readable regular files are the vast majority anyway.
719 error
= seq_open(file
, &kernfs_seq_ops
);
721 error
= seq_open(file
, NULL
);
725 ((struct seq_file
*)file
->private_data
)->private = of
;
727 /* seq_file clears PWRITE unconditionally, restore it if WRITE */
728 if (file
->f_mode
& FMODE_WRITE
)
729 file
->f_mode
|= FMODE_PWRITE
;
731 /* make sure we have open node struct */
732 error
= kernfs_get_open_node(kn
, of
);
736 /* open succeeded, put active references */
737 kernfs_put_active(kn
);
741 seq_release(inode
, file
);
743 kfree(of
->prealloc_buf
);
746 kernfs_put_active(kn
);
750 static int kernfs_fop_release(struct inode
*inode
, struct file
*filp
)
752 struct kernfs_node
*kn
= filp
->f_path
.dentry
->d_fsdata
;
753 struct kernfs_open_file
*of
= kernfs_of(filp
);
755 kernfs_put_open_node(kn
, of
);
756 seq_release(inode
, filp
);
757 kfree(of
->prealloc_buf
);
763 void kernfs_unmap_bin_file(struct kernfs_node
*kn
)
765 struct kernfs_open_node
*on
;
766 struct kernfs_open_file
*of
;
768 if (!(kn
->flags
& KERNFS_HAS_MMAP
))
771 spin_lock_irq(&kernfs_open_node_lock
);
774 atomic_inc(&on
->refcnt
);
775 spin_unlock_irq(&kernfs_open_node_lock
);
779 mutex_lock(&kernfs_open_file_mutex
);
780 list_for_each_entry(of
, &on
->files
, list
) {
781 struct inode
*inode
= file_inode(of
->file
);
782 unmap_mapping_range(inode
->i_mapping
, 0, 0, 1);
784 mutex_unlock(&kernfs_open_file_mutex
);
786 kernfs_put_open_node(kn
, NULL
);
790 * Kernfs attribute files are pollable. The idea is that you read
791 * the content and then you use 'poll' or 'select' to wait for
792 * the content to change. When the content changes (assuming the
793 * manager for the kobject supports notification), poll will
794 * return POLLERR|POLLPRI, and select will return the fd whether
795 * it is waiting for read, write, or exceptions.
796 * Once poll/select indicates that the value has changed, you
797 * need to close and re-open the file, or seek to 0 and read again.
798 * Reminder: this only works for attributes which actively support
799 * it, and it is not possible to test an attribute from userspace
800 * to see if it supports poll (Neither 'poll' nor 'select' return
801 * an appropriate error code). When in doubt, set a suitable timeout value.
803 static unsigned int kernfs_fop_poll(struct file
*filp
, poll_table
*wait
)
805 struct kernfs_open_file
*of
= kernfs_of(filp
);
806 struct kernfs_node
*kn
= filp
->f_path
.dentry
->d_fsdata
;
807 struct kernfs_open_node
*on
= kn
->attr
.open
;
809 /* need parent for the kobj, grab both */
810 if (!kernfs_get_active(kn
))
813 poll_wait(filp
, &on
->poll
, wait
);
815 kernfs_put_active(kn
);
817 if (of
->event
!= atomic_read(&on
->event
))
820 return DEFAULT_POLLMASK
;
823 return DEFAULT_POLLMASK
|POLLERR
|POLLPRI
;
826 static void kernfs_notify_workfn(struct work_struct
*work
)
828 struct kernfs_node
*kn
;
829 struct kernfs_open_node
*on
;
830 struct kernfs_super_info
*info
;
832 /* pop one off the notify_list */
833 spin_lock_irq(&kernfs_notify_lock
);
834 kn
= kernfs_notify_list
;
835 if (kn
== KERNFS_NOTIFY_EOL
) {
836 spin_unlock_irq(&kernfs_notify_lock
);
839 kernfs_notify_list
= kn
->attr
.notify_next
;
840 kn
->attr
.notify_next
= NULL
;
841 spin_unlock_irq(&kernfs_notify_lock
);
844 spin_lock_irq(&kernfs_open_node_lock
);
848 atomic_inc(&on
->event
);
849 wake_up_interruptible(&on
->poll
);
852 spin_unlock_irq(&kernfs_open_node_lock
);
855 mutex_lock(&kernfs_mutex
);
857 list_for_each_entry(info
, &kernfs_root(kn
)->supers
, node
) {
859 struct dentry
*dentry
;
861 inode
= ilookup(info
->sb
, kn
->ino
);
865 dentry
= d_find_any_alias(inode
);
867 fsnotify_parent(NULL
, dentry
, FS_MODIFY
);
868 fsnotify(inode
, FS_MODIFY
, inode
, FSNOTIFY_EVENT_INODE
,
876 mutex_unlock(&kernfs_mutex
);
882 * kernfs_notify - notify a kernfs file
883 * @kn: file to notify
885 * Notify @kn such that poll(2) on @kn wakes up. Maybe be called from any
888 void kernfs_notify(struct kernfs_node
*kn
)
890 static DECLARE_WORK(kernfs_notify_work
, kernfs_notify_workfn
);
893 if (WARN_ON(kernfs_type(kn
) != KERNFS_FILE
))
896 spin_lock_irqsave(&kernfs_notify_lock
, flags
);
897 if (!kn
->attr
.notify_next
) {
899 kn
->attr
.notify_next
= kernfs_notify_list
;
900 kernfs_notify_list
= kn
;
901 schedule_work(&kernfs_notify_work
);
903 spin_unlock_irqrestore(&kernfs_notify_lock
, flags
);
905 EXPORT_SYMBOL_GPL(kernfs_notify
);
907 const struct file_operations kernfs_file_fops
= {
908 .read
= kernfs_fop_read
,
909 .write
= kernfs_fop_write
,
910 .llseek
= generic_file_llseek
,
911 .mmap
= kernfs_fop_mmap
,
912 .open
= kernfs_fop_open
,
913 .release
= kernfs_fop_release
,
914 .poll
= kernfs_fop_poll
,
918 * __kernfs_create_file - kernfs internal function to create a file
919 * @parent: directory to create the file in
920 * @name: name of the file
921 * @mode: mode of the file
922 * @size: size of the file
923 * @ops: kernfs operations for the file
924 * @priv: private data for the file
925 * @ns: optional namespace tag of the file
926 * @name_is_static: don't copy file name
927 * @key: lockdep key for the file's active_ref, %NULL to disable lockdep
929 * Returns the created node on success, ERR_PTR() value on error.
931 struct kernfs_node
*__kernfs_create_file(struct kernfs_node
*parent
,
933 umode_t mode
, loff_t size
,
934 const struct kernfs_ops
*ops
,
935 void *priv
, const void *ns
,
937 struct lock_class_key
*key
)
939 struct kernfs_node
*kn
;
945 flags
|= KERNFS_STATIC_NAME
;
947 kn
= kernfs_new_node(parent
, name
, (mode
& S_IALLUGO
) | S_IFREG
, flags
);
949 return ERR_PTR(-ENOMEM
);
952 kn
->attr
.size
= size
;
956 #ifdef CONFIG_DEBUG_LOCK_ALLOC
958 lockdep_init_map(&kn
->dep_map
, "s_active", key
, 0);
959 kn
->flags
|= KERNFS_LOCKDEP
;
964 * kn->attr.ops is accesible only while holding active ref. We
965 * need to know whether some ops are implemented outside active
966 * ref. Cache their existence in flags.
969 kn
->flags
|= KERNFS_HAS_SEQ_SHOW
;
971 kn
->flags
|= KERNFS_HAS_MMAP
;
973 rc
= kernfs_add_one(kn
);