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1/*
2 * fs/libfs.c
3 * Library for filesystems writers.
4 */
5
6#include <linux/module.h>
7#include <linux/pagemap.h>
8#include <linux/slab.h>
9#include <linux/mount.h>
10#include <linux/vfs.h>
11#include <linux/quotaops.h>
12#include <linux/mutex.h>
13#include <linux/exportfs.h>
14#include <linux/writeback.h>
15#include <linux/buffer_head.h>
16
17#include <asm/uaccess.h>
18
19#include "internal.h"
20
21static inline int simple_positive(struct dentry *dentry)
22{
23 return dentry->d_inode && !d_unhashed(dentry);
24}
25
26int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
27 struct kstat *stat)
28{
29 struct inode *inode = dentry->d_inode;
30 generic_fillattr(inode, stat);
31 stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
32 return 0;
33}
34
35int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
36{
37 buf->f_type = dentry->d_sb->s_magic;
38 buf->f_bsize = PAGE_CACHE_SIZE;
39 buf->f_namelen = NAME_MAX;
40 return 0;
41}
42
43/*
44 * Retaining negative dentries for an in-memory filesystem just wastes
45 * memory and lookup time: arrange for them to be deleted immediately.
46 */
47static int simple_delete_dentry(const struct dentry *dentry)
48{
49 return 1;
50}
51
52/*
53 * Lookup the data. This is trivial - if the dentry didn't already
54 * exist, we know it is negative. Set d_op to delete negative dentries.
55 */
56struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
57{
58 static const struct dentry_operations simple_dentry_operations = {
59 .d_delete = simple_delete_dentry,
60 };
61
62 if (dentry->d_name.len > NAME_MAX)
63 return ERR_PTR(-ENAMETOOLONG);
64 d_set_d_op(dentry, &simple_dentry_operations);
65 d_add(dentry, NULL);
66 return NULL;
67}
68
69int dcache_dir_open(struct inode *inode, struct file *file)
70{
71 static struct qstr cursor_name = {.len = 1, .name = "."};
72
73 file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
74
75 return file->private_data ? 0 : -ENOMEM;
76}
77
78int dcache_dir_close(struct inode *inode, struct file *file)
79{
80 dput(file->private_data);
81 return 0;
82}
83
84loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
85{
86 struct dentry *dentry = file->f_path.dentry;
87 mutex_lock(&dentry->d_inode->i_mutex);
88 switch (origin) {
89 case 1:
90 offset += file->f_pos;
91 case 0:
92 if (offset >= 0)
93 break;
94 default:
95 mutex_unlock(&dentry->d_inode->i_mutex);
96 return -EINVAL;
97 }
98 if (offset != file->f_pos) {
99 file->f_pos = offset;
100 if (file->f_pos >= 2) {
101 struct list_head *p;
102 struct dentry *cursor = file->private_data;
103 loff_t n = file->f_pos - 2;
104
105 spin_lock(&dentry->d_lock);
106 /* d_lock not required for cursor */
107 list_del(&cursor->d_u.d_child);
108 p = dentry->d_subdirs.next;
109 while (n && p != &dentry->d_subdirs) {
110 struct dentry *next;
111 next = list_entry(p, struct dentry, d_u.d_child);
112 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
113 if (simple_positive(next))
114 n--;
115 spin_unlock(&next->d_lock);
116 p = p->next;
117 }
118 list_add_tail(&cursor->d_u.d_child, p);
119 spin_unlock(&dentry->d_lock);
120 }
121 }
122 mutex_unlock(&dentry->d_inode->i_mutex);
123 return offset;
124}
125
126/* Relationship between i_mode and the DT_xxx types */
127static inline unsigned char dt_type(struct inode *inode)
128{
129 return (inode->i_mode >> 12) & 15;
130}
131
132/*
133 * Directory is locked and all positive dentries in it are safe, since
134 * for ramfs-type trees they can't go away without unlink() or rmdir(),
135 * both impossible due to the lock on directory.
136 */
137
138int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
139{
140 struct dentry *dentry = filp->f_path.dentry;
141 struct dentry *cursor = filp->private_data;
142 struct list_head *p, *q = &cursor->d_u.d_child;
143 ino_t ino;
144 int i = filp->f_pos;
145
146 switch (i) {
147 case 0:
148 ino = dentry->d_inode->i_ino;
149 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
150 break;
151 filp->f_pos++;
152 i++;
153 /* fallthrough */
154 case 1:
155 ino = parent_ino(dentry);
156 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
157 break;
158 filp->f_pos++;
159 i++;
160 /* fallthrough */
161 default:
162 spin_lock(&dentry->d_lock);
163 if (filp->f_pos == 2)
164 list_move(q, &dentry->d_subdirs);
165
166 for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
167 struct dentry *next;
168 next = list_entry(p, struct dentry, d_u.d_child);
169 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
170 if (!simple_positive(next)) {
171 spin_unlock(&next->d_lock);
172 continue;
173 }
174
175 spin_unlock(&next->d_lock);
176 spin_unlock(&dentry->d_lock);
177 if (filldir(dirent, next->d_name.name,
178 next->d_name.len, filp->f_pos,
179 next->d_inode->i_ino,
180 dt_type(next->d_inode)) < 0)
181 return 0;
182 spin_lock(&dentry->d_lock);
183 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
184 /* next is still alive */
185 list_move(q, p);
186 spin_unlock(&next->d_lock);
187 p = q;
188 filp->f_pos++;
189 }
190 spin_unlock(&dentry->d_lock);
191 }
192 return 0;
193}
194
195ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
196{
197 return -EISDIR;
198}
199
200const struct file_operations simple_dir_operations = {
201 .open = dcache_dir_open,
202 .release = dcache_dir_close,
203 .llseek = dcache_dir_lseek,
204 .read = generic_read_dir,
205 .readdir = dcache_readdir,
206 .fsync = noop_fsync,
207};
208
209const struct inode_operations simple_dir_inode_operations = {
210 .lookup = simple_lookup,
211};
212
213static const struct super_operations simple_super_operations = {
214 .statfs = simple_statfs,
215};
216
217/*
218 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
219 * will never be mountable)
220 */
221struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name,
222 const struct super_operations *ops,
223 const struct dentry_operations *dops, unsigned long magic)
224{
225 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
226 struct dentry *dentry;
227 struct inode *root;
228 struct qstr d_name = {.name = name, .len = strlen(name)};
229
230 if (IS_ERR(s))
231 return ERR_CAST(s);
232
233 s->s_flags = MS_NOUSER;
234 s->s_maxbytes = MAX_LFS_FILESIZE;
235 s->s_blocksize = PAGE_SIZE;
236 s->s_blocksize_bits = PAGE_SHIFT;
237 s->s_magic = magic;
238 s->s_op = ops ? ops : &simple_super_operations;
239 s->s_time_gran = 1;
240 root = new_inode(s);
241 if (!root)
242 goto Enomem;
243 /*
244 * since this is the first inode, make it number 1. New inodes created
245 * after this must take care not to collide with it (by passing
246 * max_reserved of 1 to iunique).
247 */
248 root->i_ino = 1;
249 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
250 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
251 dentry = __d_alloc(s, &d_name);
252 if (!dentry) {
253 iput(root);
254 goto Enomem;
255 }
256 d_instantiate(dentry, root);
257 s->s_root = dentry;
258 s->s_d_op = dops;
259 s->s_flags |= MS_ACTIVE;
260 return dget(s->s_root);
261
262Enomem:
263 deactivate_locked_super(s);
264 return ERR_PTR(-ENOMEM);
265}
266
267int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
268{
269 struct inode *inode = old_dentry->d_inode;
270
271 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
272 inc_nlink(inode);
273 ihold(inode);
274 dget(dentry);
275 d_instantiate(dentry, inode);
276 return 0;
277}
278
279int simple_empty(struct dentry *dentry)
280{
281 struct dentry *child;
282 int ret = 0;
283
284 spin_lock(&dentry->d_lock);
285 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) {
286 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
287 if (simple_positive(child)) {
288 spin_unlock(&child->d_lock);
289 goto out;
290 }
291 spin_unlock(&child->d_lock);
292 }
293 ret = 1;
294out:
295 spin_unlock(&dentry->d_lock);
296 return ret;
297}
298
299int simple_unlink(struct inode *dir, struct dentry *dentry)
300{
301 struct inode *inode = dentry->d_inode;
302
303 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
304 drop_nlink(inode);
305 dput(dentry);
306 return 0;
307}
308
309int simple_rmdir(struct inode *dir, struct dentry *dentry)
310{
311 if (!simple_empty(dentry))
312 return -ENOTEMPTY;
313
314 drop_nlink(dentry->d_inode);
315 simple_unlink(dir, dentry);
316 drop_nlink(dir);
317 return 0;
318}
319
320int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
321 struct inode *new_dir, struct dentry *new_dentry)
322{
323 struct inode *inode = old_dentry->d_inode;
324 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
325
326 if (!simple_empty(new_dentry))
327 return -ENOTEMPTY;
328
329 if (new_dentry->d_inode) {
330 simple_unlink(new_dir, new_dentry);
331 if (they_are_dirs) {
332 drop_nlink(new_dentry->d_inode);
333 drop_nlink(old_dir);
334 }
335 } else if (they_are_dirs) {
336 drop_nlink(old_dir);
337 inc_nlink(new_dir);
338 }
339
340 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
341 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
342
343 return 0;
344}
345
346/**
347 * simple_setattr - setattr for simple filesystem
348 * @dentry: dentry
349 * @iattr: iattr structure
350 *
351 * Returns 0 on success, -error on failure.
352 *
353 * simple_setattr is a simple ->setattr implementation without a proper
354 * implementation of size changes.
355 *
356 * It can either be used for in-memory filesystems or special files
357 * on simple regular filesystems. Anything that needs to change on-disk
358 * or wire state on size changes needs its own setattr method.
359 */
360int simple_setattr(struct dentry *dentry, struct iattr *iattr)
361{
362 struct inode *inode = dentry->d_inode;
363 int error;
364
365 WARN_ON_ONCE(inode->i_op->truncate);
366
367 error = inode_change_ok(inode, iattr);
368 if (error)
369 return error;
370
371 if (iattr->ia_valid & ATTR_SIZE)
372 truncate_setsize(inode, iattr->ia_size);
373 setattr_copy(inode, iattr);
374 mark_inode_dirty(inode);
375 return 0;
376}
377EXPORT_SYMBOL(simple_setattr);
378
379int simple_readpage(struct file *file, struct page *page)
380{
381 clear_highpage(page);
382 flush_dcache_page(page);
383 SetPageUptodate(page);
384 unlock_page(page);
385 return 0;
386}
387
388int simple_write_begin(struct file *file, struct address_space *mapping,
389 loff_t pos, unsigned len, unsigned flags,
390 struct page **pagep, void **fsdata)
391{
392 struct page *page;
393 pgoff_t index;
394
395 index = pos >> PAGE_CACHE_SHIFT;
396
397 page = grab_cache_page_write_begin(mapping, index, flags);
398 if (!page)
399 return -ENOMEM;
400
401 *pagep = page;
402
403 if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) {
404 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
405
406 zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE);
407 }
408 return 0;
409}
410
411/**
412 * simple_write_end - .write_end helper for non-block-device FSes
413 * @available: See .write_end of address_space_operations
414 * @file: "
415 * @mapping: "
416 * @pos: "
417 * @len: "
418 * @copied: "
419 * @page: "
420 * @fsdata: "
421 *
422 * simple_write_end does the minimum needed for updating a page after writing is
423 * done. It has the same API signature as the .write_end of
424 * address_space_operations vector. So it can just be set onto .write_end for
425 * FSes that don't need any other processing. i_mutex is assumed to be held.
426 * Block based filesystems should use generic_write_end().
427 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
428 * is not called, so a filesystem that actually does store data in .write_inode
429 * should extend on what's done here with a call to mark_inode_dirty() in the
430 * case that i_size has changed.
431 */
432int simple_write_end(struct file *file, struct address_space *mapping,
433 loff_t pos, unsigned len, unsigned copied,
434 struct page *page, void *fsdata)
435{
436 struct inode *inode = page->mapping->host;
437 loff_t last_pos = pos + copied;
438
439 /* zero the stale part of the page if we did a short copy */
440 if (copied < len) {
441 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
442
443 zero_user(page, from + copied, len - copied);
444 }
445
446 if (!PageUptodate(page))
447 SetPageUptodate(page);
448 /*
449 * No need to use i_size_read() here, the i_size
450 * cannot change under us because we hold the i_mutex.
451 */
452 if (last_pos > inode->i_size)
453 i_size_write(inode, last_pos);
454
455 set_page_dirty(page);
456 unlock_page(page);
457 page_cache_release(page);
458
459 return copied;
460}
461
462/*
463 * the inodes created here are not hashed. If you use iunique to generate
464 * unique inode values later for this filesystem, then you must take care
465 * to pass it an appropriate max_reserved value to avoid collisions.
466 */
467int simple_fill_super(struct super_block *s, unsigned long magic,
468 struct tree_descr *files)
469{
470 struct inode *inode;
471 struct dentry *root;
472 struct dentry *dentry;
473 int i;
474
475 s->s_blocksize = PAGE_CACHE_SIZE;
476 s->s_blocksize_bits = PAGE_CACHE_SHIFT;
477 s->s_magic = magic;
478 s->s_op = &simple_super_operations;
479 s->s_time_gran = 1;
480
481 inode = new_inode(s);
482 if (!inode)
483 return -ENOMEM;
484 /*
485 * because the root inode is 1, the files array must not contain an
486 * entry at index 1
487 */
488 inode->i_ino = 1;
489 inode->i_mode = S_IFDIR | 0755;
490 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
491 inode->i_op = &simple_dir_inode_operations;
492 inode->i_fop = &simple_dir_operations;
493 inode->i_nlink = 2;
494 root = d_alloc_root(inode);
495 if (!root) {
496 iput(inode);
497 return -ENOMEM;
498 }
499 for (i = 0; !files->name || files->name[0]; i++, files++) {
500 if (!files->name)
501 continue;
502
503 /* warn if it tries to conflict with the root inode */
504 if (unlikely(i == 1))
505 printk(KERN_WARNING "%s: %s passed in a files array"
506 "with an index of 1!\n", __func__,
507 s->s_type->name);
508
509 dentry = d_alloc_name(root, files->name);
510 if (!dentry)
511 goto out;
512 inode = new_inode(s);
513 if (!inode)
514 goto out;
515 inode->i_mode = S_IFREG | files->mode;
516 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
517 inode->i_fop = files->ops;
518 inode->i_ino = i;
519 d_add(dentry, inode);
520 }
521 s->s_root = root;
522 return 0;
523out:
524 d_genocide(root);
525 dput(root);
526 return -ENOMEM;
527}
528
529static DEFINE_SPINLOCK(pin_fs_lock);
530
531int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
532{
533 struct vfsmount *mnt = NULL;
534 spin_lock(&pin_fs_lock);
535 if (unlikely(!*mount)) {
536 spin_unlock(&pin_fs_lock);
537 mnt = vfs_kern_mount(type, 0, type->name, NULL);
538 if (IS_ERR(mnt))
539 return PTR_ERR(mnt);
540 spin_lock(&pin_fs_lock);
541 if (!*mount)
542 *mount = mnt;
543 }
544 mntget(*mount);
545 ++*count;
546 spin_unlock(&pin_fs_lock);
547 mntput(mnt);
548 return 0;
549}
550
551void simple_release_fs(struct vfsmount **mount, int *count)
552{
553 struct vfsmount *mnt;
554 spin_lock(&pin_fs_lock);
555 mnt = *mount;
556 if (!--*count)
557 *mount = NULL;
558 spin_unlock(&pin_fs_lock);
559 mntput(mnt);
560}
561
562/**
563 * simple_read_from_buffer - copy data from the buffer to user space
564 * @to: the user space buffer to read to
565 * @count: the maximum number of bytes to read
566 * @ppos: the current position in the buffer
567 * @from: the buffer to read from
568 * @available: the size of the buffer
569 *
570 * The simple_read_from_buffer() function reads up to @count bytes from the
571 * buffer @from at offset @ppos into the user space address starting at @to.
572 *
573 * On success, the number of bytes read is returned and the offset @ppos is
574 * advanced by this number, or negative value is returned on error.
575 **/
576ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
577 const void *from, size_t available)
578{
579 loff_t pos = *ppos;
580 size_t ret;
581
582 if (pos < 0)
583 return -EINVAL;
584 if (pos >= available || !count)
585 return 0;
586 if (count > available - pos)
587 count = available - pos;
588 ret = copy_to_user(to, from + pos, count);
589 if (ret == count)
590 return -EFAULT;
591 count -= ret;
592 *ppos = pos + count;
593 return count;
594}
595
596/**
597 * simple_write_to_buffer - copy data from user space to the buffer
598 * @to: the buffer to write to
599 * @available: the size of the buffer
600 * @ppos: the current position in the buffer
601 * @from: the user space buffer to read from
602 * @count: the maximum number of bytes to read
603 *
604 * The simple_write_to_buffer() function reads up to @count bytes from the user
605 * space address starting at @from into the buffer @to at offset @ppos.
606 *
607 * On success, the number of bytes written is returned and the offset @ppos is
608 * advanced by this number, or negative value is returned on error.
609 **/
610ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
611 const void __user *from, size_t count)
612{
613 loff_t pos = *ppos;
614 size_t res;
615
616 if (pos < 0)
617 return -EINVAL;
618 if (pos >= available || !count)
619 return 0;
620 if (count > available - pos)
621 count = available - pos;
622 res = copy_from_user(to + pos, from, count);
623 if (res == count)
624 return -EFAULT;
625 count -= res;
626 *ppos = pos + count;
627 return count;
628}
629
630/**
631 * memory_read_from_buffer - copy data from the buffer
632 * @to: the kernel space buffer to read to
633 * @count: the maximum number of bytes to read
634 * @ppos: the current position in the buffer
635 * @from: the buffer to read from
636 * @available: the size of the buffer
637 *
638 * The memory_read_from_buffer() function reads up to @count bytes from the
639 * buffer @from at offset @ppos into the kernel space address starting at @to.
640 *
641 * On success, the number of bytes read is returned and the offset @ppos is
642 * advanced by this number, or negative value is returned on error.
643 **/
644ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
645 const void *from, size_t available)
646{
647 loff_t pos = *ppos;
648
649 if (pos < 0)
650 return -EINVAL;
651 if (pos >= available)
652 return 0;
653 if (count > available - pos)
654 count = available - pos;
655 memcpy(to, from + pos, count);
656 *ppos = pos + count;
657
658 return count;
659}
660
661/*
662 * Transaction based IO.
663 * The file expects a single write which triggers the transaction, and then
664 * possibly a read which collects the result - which is stored in a
665 * file-local buffer.
666 */
667
668void simple_transaction_set(struct file *file, size_t n)
669{
670 struct simple_transaction_argresp *ar = file->private_data;
671
672 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
673
674 /*
675 * The barrier ensures that ar->size will really remain zero until
676 * ar->data is ready for reading.
677 */
678 smp_mb();
679 ar->size = n;
680}
681
682char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
683{
684 struct simple_transaction_argresp *ar;
685 static DEFINE_SPINLOCK(simple_transaction_lock);
686
687 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
688 return ERR_PTR(-EFBIG);
689
690 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
691 if (!ar)
692 return ERR_PTR(-ENOMEM);
693
694 spin_lock(&simple_transaction_lock);
695
696 /* only one write allowed per open */
697 if (file->private_data) {
698 spin_unlock(&simple_transaction_lock);
699 free_page((unsigned long)ar);
700 return ERR_PTR(-EBUSY);
701 }
702
703 file->private_data = ar;
704
705 spin_unlock(&simple_transaction_lock);
706
707 if (copy_from_user(ar->data, buf, size))
708 return ERR_PTR(-EFAULT);
709
710 return ar->data;
711}
712
713ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
714{
715 struct simple_transaction_argresp *ar = file->private_data;
716
717 if (!ar)
718 return 0;
719 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
720}
721
722int simple_transaction_release(struct inode *inode, struct file *file)
723{
724 free_page((unsigned long)file->private_data);
725 return 0;
726}
727
728/* Simple attribute files */
729
730struct simple_attr {
731 int (*get)(void *, u64 *);
732 int (*set)(void *, u64);
733 char get_buf[24]; /* enough to store a u64 and "\n\0" */
734 char set_buf[24];
735 void *data;
736 const char *fmt; /* format for read operation */
737 struct mutex mutex; /* protects access to these buffers */
738};
739
740/* simple_attr_open is called by an actual attribute open file operation
741 * to set the attribute specific access operations. */
742int simple_attr_open(struct inode *inode, struct file *file,
743 int (*get)(void *, u64 *), int (*set)(void *, u64),
744 const char *fmt)
745{
746 struct simple_attr *attr;
747
748 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
749 if (!attr)
750 return -ENOMEM;
751
752 attr->get = get;
753 attr->set = set;
754 attr->data = inode->i_private;
755 attr->fmt = fmt;
756 mutex_init(&attr->mutex);
757
758 file->private_data = attr;
759
760 return nonseekable_open(inode, file);
761}
762
763int simple_attr_release(struct inode *inode, struct file *file)
764{
765 kfree(file->private_data);
766 return 0;
767}
768
769/* read from the buffer that is filled with the get function */
770ssize_t simple_attr_read(struct file *file, char __user *buf,
771 size_t len, loff_t *ppos)
772{
773 struct simple_attr *attr;
774 size_t size;
775 ssize_t ret;
776
777 attr = file->private_data;
778
779 if (!attr->get)
780 return -EACCES;
781
782 ret = mutex_lock_interruptible(&attr->mutex);
783 if (ret)
784 return ret;
785
786 if (*ppos) { /* continued read */
787 size = strlen(attr->get_buf);
788 } else { /* first read */
789 u64 val;
790 ret = attr->get(attr->data, &val);
791 if (ret)
792 goto out;
793
794 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
795 attr->fmt, (unsigned long long)val);
796 }
797
798 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
799out:
800 mutex_unlock(&attr->mutex);
801 return ret;
802}
803
804/* interpret the buffer as a number to call the set function with */
805ssize_t simple_attr_write(struct file *file, const char __user *buf,
806 size_t len, loff_t *ppos)
807{
808 struct simple_attr *attr;
809 u64 val;
810 size_t size;
811 ssize_t ret;
812
813 attr = file->private_data;
814 if (!attr->set)
815 return -EACCES;
816
817 ret = mutex_lock_interruptible(&attr->mutex);
818 if (ret)
819 return ret;
820
821 ret = -EFAULT;
822 size = min(sizeof(attr->set_buf) - 1, len);
823 if (copy_from_user(attr->set_buf, buf, size))
824 goto out;
825
826 attr->set_buf[size] = '\0';
827 val = simple_strtoll(attr->set_buf, NULL, 0);
828 ret = attr->set(attr->data, val);
829 if (ret == 0)
830 ret = len; /* on success, claim we got the whole input */
831out:
832 mutex_unlock(&attr->mutex);
833 return ret;
834}
835
836/**
837 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
838 * @sb: filesystem to do the file handle conversion on
839 * @fid: file handle to convert
840 * @fh_len: length of the file handle in bytes
841 * @fh_type: type of file handle
842 * @get_inode: filesystem callback to retrieve inode
843 *
844 * This function decodes @fid as long as it has one of the well-known
845 * Linux filehandle types and calls @get_inode on it to retrieve the
846 * inode for the object specified in the file handle.
847 */
848struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
849 int fh_len, int fh_type, struct inode *(*get_inode)
850 (struct super_block *sb, u64 ino, u32 gen))
851{
852 struct inode *inode = NULL;
853
854 if (fh_len < 2)
855 return NULL;
856
857 switch (fh_type) {
858 case FILEID_INO32_GEN:
859 case FILEID_INO32_GEN_PARENT:
860 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
861 break;
862 }
863
864 return d_obtain_alias(inode);
865}
866EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
867
868/**
869 * generic_fh_to_dentry - generic helper for the fh_to_parent export operation
870 * @sb: filesystem to do the file handle conversion on
871 * @fid: file handle to convert
872 * @fh_len: length of the file handle in bytes
873 * @fh_type: type of file handle
874 * @get_inode: filesystem callback to retrieve inode
875 *
876 * This function decodes @fid as long as it has one of the well-known
877 * Linux filehandle types and calls @get_inode on it to retrieve the
878 * inode for the _parent_ object specified in the file handle if it
879 * is specified in the file handle, or NULL otherwise.
880 */
881struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
882 int fh_len, int fh_type, struct inode *(*get_inode)
883 (struct super_block *sb, u64 ino, u32 gen))
884{
885 struct inode *inode = NULL;
886
887 if (fh_len <= 2)
888 return NULL;
889
890 switch (fh_type) {
891 case FILEID_INO32_GEN_PARENT:
892 inode = get_inode(sb, fid->i32.parent_ino,
893 (fh_len > 3 ? fid->i32.parent_gen : 0));
894 break;
895 }
896
897 return d_obtain_alias(inode);
898}
899EXPORT_SYMBOL_GPL(generic_fh_to_parent);
900
901/**
902 * generic_file_fsync - generic fsync implementation for simple filesystems
903 * @file: file to synchronize
904 * @datasync: only synchronize essential metadata if true
905 *
906 * This is a generic implementation of the fsync method for simple
907 * filesystems which track all non-inode metadata in the buffers list
908 * hanging off the address_space structure.
909 */
910int generic_file_fsync(struct file *file, loff_t start, loff_t end,
911 int datasync)
912{
913 struct inode *inode = file->f_mapping->host;
914 int err;
915 int ret;
916
917 err = filemap_write_and_wait_range(inode->i_mapping, start, end);
918 if (err)
919 return err;
920
921 mutex_lock(&inode->i_mutex);
922 ret = sync_mapping_buffers(inode->i_mapping);
923 if (!(inode->i_state & I_DIRTY))
924 goto out;
925 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
926 goto out;
927
928 err = sync_inode_metadata(inode, 1);
929 if (ret == 0)
930 ret = err;
931out:
932 mutex_unlock(&inode->i_mutex);
933 return ret;
934}
935EXPORT_SYMBOL(generic_file_fsync);
936
937/**
938 * generic_check_addressable - Check addressability of file system
939 * @blocksize_bits: log of file system block size
940 * @num_blocks: number of blocks in file system
941 *
942 * Determine whether a file system with @num_blocks blocks (and a
943 * block size of 2**@blocksize_bits) is addressable by the sector_t
944 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
945 */
946int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
947{
948 u64 last_fs_block = num_blocks - 1;
949 u64 last_fs_page =
950 last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits);
951
952 if (unlikely(num_blocks == 0))
953 return 0;
954
955 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT))
956 return -EINVAL;
957
958 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
959 (last_fs_page > (pgoff_t)(~0ULL))) {
960 return -EFBIG;
961 }
962 return 0;
963}
964EXPORT_SYMBOL(generic_check_addressable);
965
966/*
967 * No-op implementation of ->fsync for in-memory filesystems.
968 */
969int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
970{
971 return 0;
972}
973
974EXPORT_SYMBOL(dcache_dir_close);
975EXPORT_SYMBOL(dcache_dir_lseek);
976EXPORT_SYMBOL(dcache_dir_open);
977EXPORT_SYMBOL(dcache_readdir);
978EXPORT_SYMBOL(generic_read_dir);
979EXPORT_SYMBOL(mount_pseudo);
980EXPORT_SYMBOL(simple_write_begin);
981EXPORT_SYMBOL(simple_write_end);
982EXPORT_SYMBOL(simple_dir_inode_operations);
983EXPORT_SYMBOL(simple_dir_operations);
984EXPORT_SYMBOL(simple_empty);
985EXPORT_SYMBOL(simple_fill_super);
986EXPORT_SYMBOL(simple_getattr);
987EXPORT_SYMBOL(simple_link);
988EXPORT_SYMBOL(simple_lookup);
989EXPORT_SYMBOL(simple_pin_fs);
990EXPORT_SYMBOL(simple_readpage);
991EXPORT_SYMBOL(simple_release_fs);
992EXPORT_SYMBOL(simple_rename);
993EXPORT_SYMBOL(simple_rmdir);
994EXPORT_SYMBOL(simple_statfs);
995EXPORT_SYMBOL(noop_fsync);
996EXPORT_SYMBOL(simple_unlink);
997EXPORT_SYMBOL(simple_read_from_buffer);
998EXPORT_SYMBOL(simple_write_to_buffer);
999EXPORT_SYMBOL(memory_read_from_buffer);
1000EXPORT_SYMBOL(simple_transaction_set);
1001EXPORT_SYMBOL(simple_transaction_get);
1002EXPORT_SYMBOL(simple_transaction_read);
1003EXPORT_SYMBOL(simple_transaction_release);
1004EXPORT_SYMBOL_GPL(simple_attr_open);
1005EXPORT_SYMBOL_GPL(simple_attr_release);
1006EXPORT_SYMBOL_GPL(simple_attr_read);
1007EXPORT_SYMBOL_GPL(simple_attr_write);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * fs/libfs.c
4 * Library for filesystems writers.
5 */
6
7#include <linux/blkdev.h>
8#include <linux/export.h>
9#include <linux/pagemap.h>
10#include <linux/slab.h>
11#include <linux/cred.h>
12#include <linux/mount.h>
13#include <linux/vfs.h>
14#include <linux/quotaops.h>
15#include <linux/mutex.h>
16#include <linux/namei.h>
17#include <linux/exportfs.h>
18#include <linux/writeback.h>
19#include <linux/buffer_head.h> /* sync_mapping_buffers */
20#include <linux/fs_context.h>
21#include <linux/pseudo_fs.h>
22#include <linux/fsnotify.h>
23
24#include <linux/uaccess.h>
25
26#include "internal.h"
27
28int simple_getattr(const struct path *path, struct kstat *stat,
29 u32 request_mask, unsigned int query_flags)
30{
31 struct inode *inode = d_inode(path->dentry);
32 generic_fillattr(inode, stat);
33 stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
34 return 0;
35}
36EXPORT_SYMBOL(simple_getattr);
37
38int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
39{
40 buf->f_type = dentry->d_sb->s_magic;
41 buf->f_bsize = PAGE_SIZE;
42 buf->f_namelen = NAME_MAX;
43 return 0;
44}
45EXPORT_SYMBOL(simple_statfs);
46
47/*
48 * Retaining negative dentries for an in-memory filesystem just wastes
49 * memory and lookup time: arrange for them to be deleted immediately.
50 */
51int always_delete_dentry(const struct dentry *dentry)
52{
53 return 1;
54}
55EXPORT_SYMBOL(always_delete_dentry);
56
57const struct dentry_operations simple_dentry_operations = {
58 .d_delete = always_delete_dentry,
59};
60EXPORT_SYMBOL(simple_dentry_operations);
61
62/*
63 * Lookup the data. This is trivial - if the dentry didn't already
64 * exist, we know it is negative. Set d_op to delete negative dentries.
65 */
66struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
67{
68 if (dentry->d_name.len > NAME_MAX)
69 return ERR_PTR(-ENAMETOOLONG);
70 if (!dentry->d_sb->s_d_op)
71 d_set_d_op(dentry, &simple_dentry_operations);
72 d_add(dentry, NULL);
73 return NULL;
74}
75EXPORT_SYMBOL(simple_lookup);
76
77int dcache_dir_open(struct inode *inode, struct file *file)
78{
79 file->private_data = d_alloc_cursor(file->f_path.dentry);
80
81 return file->private_data ? 0 : -ENOMEM;
82}
83EXPORT_SYMBOL(dcache_dir_open);
84
85int dcache_dir_close(struct inode *inode, struct file *file)
86{
87 dput(file->private_data);
88 return 0;
89}
90EXPORT_SYMBOL(dcache_dir_close);
91
92/* parent is locked at least shared */
93/*
94 * Returns an element of siblings' list.
95 * We are looking for <count>th positive after <p>; if
96 * found, dentry is grabbed and returned to caller.
97 * If no such element exists, NULL is returned.
98 */
99static struct dentry *scan_positives(struct dentry *cursor,
100 struct list_head *p,
101 loff_t count,
102 struct dentry *last)
103{
104 struct dentry *dentry = cursor->d_parent, *found = NULL;
105
106 spin_lock(&dentry->d_lock);
107 while ((p = p->next) != &dentry->d_subdirs) {
108 struct dentry *d = list_entry(p, struct dentry, d_child);
109 // we must at least skip cursors, to avoid livelocks
110 if (d->d_flags & DCACHE_DENTRY_CURSOR)
111 continue;
112 if (simple_positive(d) && !--count) {
113 spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
114 if (simple_positive(d))
115 found = dget_dlock(d);
116 spin_unlock(&d->d_lock);
117 if (likely(found))
118 break;
119 count = 1;
120 }
121 if (need_resched()) {
122 list_move(&cursor->d_child, p);
123 p = &cursor->d_child;
124 spin_unlock(&dentry->d_lock);
125 cond_resched();
126 spin_lock(&dentry->d_lock);
127 }
128 }
129 spin_unlock(&dentry->d_lock);
130 dput(last);
131 return found;
132}
133
134loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
135{
136 struct dentry *dentry = file->f_path.dentry;
137 switch (whence) {
138 case 1:
139 offset += file->f_pos;
140 fallthrough;
141 case 0:
142 if (offset >= 0)
143 break;
144 fallthrough;
145 default:
146 return -EINVAL;
147 }
148 if (offset != file->f_pos) {
149 struct dentry *cursor = file->private_data;
150 struct dentry *to = NULL;
151
152 inode_lock_shared(dentry->d_inode);
153
154 if (offset > 2)
155 to = scan_positives(cursor, &dentry->d_subdirs,
156 offset - 2, NULL);
157 spin_lock(&dentry->d_lock);
158 if (to)
159 list_move(&cursor->d_child, &to->d_child);
160 else
161 list_del_init(&cursor->d_child);
162 spin_unlock(&dentry->d_lock);
163 dput(to);
164
165 file->f_pos = offset;
166
167 inode_unlock_shared(dentry->d_inode);
168 }
169 return offset;
170}
171EXPORT_SYMBOL(dcache_dir_lseek);
172
173/* Relationship between i_mode and the DT_xxx types */
174static inline unsigned char dt_type(struct inode *inode)
175{
176 return (inode->i_mode >> 12) & 15;
177}
178
179/*
180 * Directory is locked and all positive dentries in it are safe, since
181 * for ramfs-type trees they can't go away without unlink() or rmdir(),
182 * both impossible due to the lock on directory.
183 */
184
185int dcache_readdir(struct file *file, struct dir_context *ctx)
186{
187 struct dentry *dentry = file->f_path.dentry;
188 struct dentry *cursor = file->private_data;
189 struct list_head *anchor = &dentry->d_subdirs;
190 struct dentry *next = NULL;
191 struct list_head *p;
192
193 if (!dir_emit_dots(file, ctx))
194 return 0;
195
196 if (ctx->pos == 2)
197 p = anchor;
198 else if (!list_empty(&cursor->d_child))
199 p = &cursor->d_child;
200 else
201 return 0;
202
203 while ((next = scan_positives(cursor, p, 1, next)) != NULL) {
204 if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
205 d_inode(next)->i_ino, dt_type(d_inode(next))))
206 break;
207 ctx->pos++;
208 p = &next->d_child;
209 }
210 spin_lock(&dentry->d_lock);
211 if (next)
212 list_move_tail(&cursor->d_child, &next->d_child);
213 else
214 list_del_init(&cursor->d_child);
215 spin_unlock(&dentry->d_lock);
216 dput(next);
217
218 return 0;
219}
220EXPORT_SYMBOL(dcache_readdir);
221
222ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
223{
224 return -EISDIR;
225}
226EXPORT_SYMBOL(generic_read_dir);
227
228const struct file_operations simple_dir_operations = {
229 .open = dcache_dir_open,
230 .release = dcache_dir_close,
231 .llseek = dcache_dir_lseek,
232 .read = generic_read_dir,
233 .iterate_shared = dcache_readdir,
234 .fsync = noop_fsync,
235};
236EXPORT_SYMBOL(simple_dir_operations);
237
238const struct inode_operations simple_dir_inode_operations = {
239 .lookup = simple_lookup,
240};
241EXPORT_SYMBOL(simple_dir_inode_operations);
242
243static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev)
244{
245 struct dentry *child = NULL;
246 struct list_head *p = prev ? &prev->d_child : &parent->d_subdirs;
247
248 spin_lock(&parent->d_lock);
249 while ((p = p->next) != &parent->d_subdirs) {
250 struct dentry *d = container_of(p, struct dentry, d_child);
251 if (simple_positive(d)) {
252 spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
253 if (simple_positive(d))
254 child = dget_dlock(d);
255 spin_unlock(&d->d_lock);
256 if (likely(child))
257 break;
258 }
259 }
260 spin_unlock(&parent->d_lock);
261 dput(prev);
262 return child;
263}
264
265void simple_recursive_removal(struct dentry *dentry,
266 void (*callback)(struct dentry *))
267{
268 struct dentry *this = dget(dentry);
269 while (true) {
270 struct dentry *victim = NULL, *child;
271 struct inode *inode = this->d_inode;
272
273 inode_lock(inode);
274 if (d_is_dir(this))
275 inode->i_flags |= S_DEAD;
276 while ((child = find_next_child(this, victim)) == NULL) {
277 // kill and ascend
278 // update metadata while it's still locked
279 inode->i_ctime = current_time(inode);
280 clear_nlink(inode);
281 inode_unlock(inode);
282 victim = this;
283 this = this->d_parent;
284 inode = this->d_inode;
285 inode_lock(inode);
286 if (simple_positive(victim)) {
287 d_invalidate(victim); // avoid lost mounts
288 if (d_is_dir(victim))
289 fsnotify_rmdir(inode, victim);
290 else
291 fsnotify_unlink(inode, victim);
292 if (callback)
293 callback(victim);
294 dput(victim); // unpin it
295 }
296 if (victim == dentry) {
297 inode->i_ctime = inode->i_mtime =
298 current_time(inode);
299 if (d_is_dir(dentry))
300 drop_nlink(inode);
301 inode_unlock(inode);
302 dput(dentry);
303 return;
304 }
305 }
306 inode_unlock(inode);
307 this = child;
308 }
309}
310EXPORT_SYMBOL(simple_recursive_removal);
311
312static const struct super_operations simple_super_operations = {
313 .statfs = simple_statfs,
314};
315
316static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc)
317{
318 struct pseudo_fs_context *ctx = fc->fs_private;
319 struct inode *root;
320
321 s->s_maxbytes = MAX_LFS_FILESIZE;
322 s->s_blocksize = PAGE_SIZE;
323 s->s_blocksize_bits = PAGE_SHIFT;
324 s->s_magic = ctx->magic;
325 s->s_op = ctx->ops ?: &simple_super_operations;
326 s->s_xattr = ctx->xattr;
327 s->s_time_gran = 1;
328 root = new_inode(s);
329 if (!root)
330 return -ENOMEM;
331
332 /*
333 * since this is the first inode, make it number 1. New inodes created
334 * after this must take care not to collide with it (by passing
335 * max_reserved of 1 to iunique).
336 */
337 root->i_ino = 1;
338 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
339 root->i_atime = root->i_mtime = root->i_ctime = current_time(root);
340 s->s_root = d_make_root(root);
341 if (!s->s_root)
342 return -ENOMEM;
343 s->s_d_op = ctx->dops;
344 return 0;
345}
346
347static int pseudo_fs_get_tree(struct fs_context *fc)
348{
349 return get_tree_nodev(fc, pseudo_fs_fill_super);
350}
351
352static void pseudo_fs_free(struct fs_context *fc)
353{
354 kfree(fc->fs_private);
355}
356
357static const struct fs_context_operations pseudo_fs_context_ops = {
358 .free = pseudo_fs_free,
359 .get_tree = pseudo_fs_get_tree,
360};
361
362/*
363 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
364 * will never be mountable)
365 */
366struct pseudo_fs_context *init_pseudo(struct fs_context *fc,
367 unsigned long magic)
368{
369 struct pseudo_fs_context *ctx;
370
371 ctx = kzalloc(sizeof(struct pseudo_fs_context), GFP_KERNEL);
372 if (likely(ctx)) {
373 ctx->magic = magic;
374 fc->fs_private = ctx;
375 fc->ops = &pseudo_fs_context_ops;
376 fc->sb_flags |= SB_NOUSER;
377 fc->global = true;
378 }
379 return ctx;
380}
381EXPORT_SYMBOL(init_pseudo);
382
383int simple_open(struct inode *inode, struct file *file)
384{
385 if (inode->i_private)
386 file->private_data = inode->i_private;
387 return 0;
388}
389EXPORT_SYMBOL(simple_open);
390
391int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
392{
393 struct inode *inode = d_inode(old_dentry);
394
395 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
396 inc_nlink(inode);
397 ihold(inode);
398 dget(dentry);
399 d_instantiate(dentry, inode);
400 return 0;
401}
402EXPORT_SYMBOL(simple_link);
403
404int simple_empty(struct dentry *dentry)
405{
406 struct dentry *child;
407 int ret = 0;
408
409 spin_lock(&dentry->d_lock);
410 list_for_each_entry(child, &dentry->d_subdirs, d_child) {
411 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
412 if (simple_positive(child)) {
413 spin_unlock(&child->d_lock);
414 goto out;
415 }
416 spin_unlock(&child->d_lock);
417 }
418 ret = 1;
419out:
420 spin_unlock(&dentry->d_lock);
421 return ret;
422}
423EXPORT_SYMBOL(simple_empty);
424
425int simple_unlink(struct inode *dir, struct dentry *dentry)
426{
427 struct inode *inode = d_inode(dentry);
428
429 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
430 drop_nlink(inode);
431 dput(dentry);
432 return 0;
433}
434EXPORT_SYMBOL(simple_unlink);
435
436int simple_rmdir(struct inode *dir, struct dentry *dentry)
437{
438 if (!simple_empty(dentry))
439 return -ENOTEMPTY;
440
441 drop_nlink(d_inode(dentry));
442 simple_unlink(dir, dentry);
443 drop_nlink(dir);
444 return 0;
445}
446EXPORT_SYMBOL(simple_rmdir);
447
448int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
449 struct inode *new_dir, struct dentry *new_dentry,
450 unsigned int flags)
451{
452 struct inode *inode = d_inode(old_dentry);
453 int they_are_dirs = d_is_dir(old_dentry);
454
455 if (flags & ~RENAME_NOREPLACE)
456 return -EINVAL;
457
458 if (!simple_empty(new_dentry))
459 return -ENOTEMPTY;
460
461 if (d_really_is_positive(new_dentry)) {
462 simple_unlink(new_dir, new_dentry);
463 if (they_are_dirs) {
464 drop_nlink(d_inode(new_dentry));
465 drop_nlink(old_dir);
466 }
467 } else if (they_are_dirs) {
468 drop_nlink(old_dir);
469 inc_nlink(new_dir);
470 }
471
472 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
473 new_dir->i_mtime = inode->i_ctime = current_time(old_dir);
474
475 return 0;
476}
477EXPORT_SYMBOL(simple_rename);
478
479/**
480 * simple_setattr - setattr for simple filesystem
481 * @dentry: dentry
482 * @iattr: iattr structure
483 *
484 * Returns 0 on success, -error on failure.
485 *
486 * simple_setattr is a simple ->setattr implementation without a proper
487 * implementation of size changes.
488 *
489 * It can either be used for in-memory filesystems or special files
490 * on simple regular filesystems. Anything that needs to change on-disk
491 * or wire state on size changes needs its own setattr method.
492 */
493int simple_setattr(struct dentry *dentry, struct iattr *iattr)
494{
495 struct inode *inode = d_inode(dentry);
496 int error;
497
498 error = setattr_prepare(dentry, iattr);
499 if (error)
500 return error;
501
502 if (iattr->ia_valid & ATTR_SIZE)
503 truncate_setsize(inode, iattr->ia_size);
504 setattr_copy(inode, iattr);
505 mark_inode_dirty(inode);
506 return 0;
507}
508EXPORT_SYMBOL(simple_setattr);
509
510int simple_readpage(struct file *file, struct page *page)
511{
512 clear_highpage(page);
513 flush_dcache_page(page);
514 SetPageUptodate(page);
515 unlock_page(page);
516 return 0;
517}
518EXPORT_SYMBOL(simple_readpage);
519
520int simple_write_begin(struct file *file, struct address_space *mapping,
521 loff_t pos, unsigned len, unsigned flags,
522 struct page **pagep, void **fsdata)
523{
524 struct page *page;
525 pgoff_t index;
526
527 index = pos >> PAGE_SHIFT;
528
529 page = grab_cache_page_write_begin(mapping, index, flags);
530 if (!page)
531 return -ENOMEM;
532
533 *pagep = page;
534
535 if (!PageUptodate(page) && (len != PAGE_SIZE)) {
536 unsigned from = pos & (PAGE_SIZE - 1);
537
538 zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
539 }
540 return 0;
541}
542EXPORT_SYMBOL(simple_write_begin);
543
544/**
545 * simple_write_end - .write_end helper for non-block-device FSes
546 * @file: See .write_end of address_space_operations
547 * @mapping: "
548 * @pos: "
549 * @len: "
550 * @copied: "
551 * @page: "
552 * @fsdata: "
553 *
554 * simple_write_end does the minimum needed for updating a page after writing is
555 * done. It has the same API signature as the .write_end of
556 * address_space_operations vector. So it can just be set onto .write_end for
557 * FSes that don't need any other processing. i_mutex is assumed to be held.
558 * Block based filesystems should use generic_write_end().
559 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
560 * is not called, so a filesystem that actually does store data in .write_inode
561 * should extend on what's done here with a call to mark_inode_dirty() in the
562 * case that i_size has changed.
563 *
564 * Use *ONLY* with simple_readpage()
565 */
566int simple_write_end(struct file *file, struct address_space *mapping,
567 loff_t pos, unsigned len, unsigned copied,
568 struct page *page, void *fsdata)
569{
570 struct inode *inode = page->mapping->host;
571 loff_t last_pos = pos + copied;
572
573 /* zero the stale part of the page if we did a short copy */
574 if (!PageUptodate(page)) {
575 if (copied < len) {
576 unsigned from = pos & (PAGE_SIZE - 1);
577
578 zero_user(page, from + copied, len - copied);
579 }
580 SetPageUptodate(page);
581 }
582 /*
583 * No need to use i_size_read() here, the i_size
584 * cannot change under us because we hold the i_mutex.
585 */
586 if (last_pos > inode->i_size)
587 i_size_write(inode, last_pos);
588
589 set_page_dirty(page);
590 unlock_page(page);
591 put_page(page);
592
593 return copied;
594}
595EXPORT_SYMBOL(simple_write_end);
596
597/*
598 * the inodes created here are not hashed. If you use iunique to generate
599 * unique inode values later for this filesystem, then you must take care
600 * to pass it an appropriate max_reserved value to avoid collisions.
601 */
602int simple_fill_super(struct super_block *s, unsigned long magic,
603 const struct tree_descr *files)
604{
605 struct inode *inode;
606 struct dentry *root;
607 struct dentry *dentry;
608 int i;
609
610 s->s_blocksize = PAGE_SIZE;
611 s->s_blocksize_bits = PAGE_SHIFT;
612 s->s_magic = magic;
613 s->s_op = &simple_super_operations;
614 s->s_time_gran = 1;
615
616 inode = new_inode(s);
617 if (!inode)
618 return -ENOMEM;
619 /*
620 * because the root inode is 1, the files array must not contain an
621 * entry at index 1
622 */
623 inode->i_ino = 1;
624 inode->i_mode = S_IFDIR | 0755;
625 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
626 inode->i_op = &simple_dir_inode_operations;
627 inode->i_fop = &simple_dir_operations;
628 set_nlink(inode, 2);
629 root = d_make_root(inode);
630 if (!root)
631 return -ENOMEM;
632 for (i = 0; !files->name || files->name[0]; i++, files++) {
633 if (!files->name)
634 continue;
635
636 /* warn if it tries to conflict with the root inode */
637 if (unlikely(i == 1))
638 printk(KERN_WARNING "%s: %s passed in a files array"
639 "with an index of 1!\n", __func__,
640 s->s_type->name);
641
642 dentry = d_alloc_name(root, files->name);
643 if (!dentry)
644 goto out;
645 inode = new_inode(s);
646 if (!inode) {
647 dput(dentry);
648 goto out;
649 }
650 inode->i_mode = S_IFREG | files->mode;
651 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
652 inode->i_fop = files->ops;
653 inode->i_ino = i;
654 d_add(dentry, inode);
655 }
656 s->s_root = root;
657 return 0;
658out:
659 d_genocide(root);
660 shrink_dcache_parent(root);
661 dput(root);
662 return -ENOMEM;
663}
664EXPORT_SYMBOL(simple_fill_super);
665
666static DEFINE_SPINLOCK(pin_fs_lock);
667
668int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
669{
670 struct vfsmount *mnt = NULL;
671 spin_lock(&pin_fs_lock);
672 if (unlikely(!*mount)) {
673 spin_unlock(&pin_fs_lock);
674 mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
675 if (IS_ERR(mnt))
676 return PTR_ERR(mnt);
677 spin_lock(&pin_fs_lock);
678 if (!*mount)
679 *mount = mnt;
680 }
681 mntget(*mount);
682 ++*count;
683 spin_unlock(&pin_fs_lock);
684 mntput(mnt);
685 return 0;
686}
687EXPORT_SYMBOL(simple_pin_fs);
688
689void simple_release_fs(struct vfsmount **mount, int *count)
690{
691 struct vfsmount *mnt;
692 spin_lock(&pin_fs_lock);
693 mnt = *mount;
694 if (!--*count)
695 *mount = NULL;
696 spin_unlock(&pin_fs_lock);
697 mntput(mnt);
698}
699EXPORT_SYMBOL(simple_release_fs);
700
701/**
702 * simple_read_from_buffer - copy data from the buffer to user space
703 * @to: the user space buffer to read to
704 * @count: the maximum number of bytes to read
705 * @ppos: the current position in the buffer
706 * @from: the buffer to read from
707 * @available: the size of the buffer
708 *
709 * The simple_read_from_buffer() function reads up to @count bytes from the
710 * buffer @from at offset @ppos into the user space address starting at @to.
711 *
712 * On success, the number of bytes read is returned and the offset @ppos is
713 * advanced by this number, or negative value is returned on error.
714 **/
715ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
716 const void *from, size_t available)
717{
718 loff_t pos = *ppos;
719 size_t ret;
720
721 if (pos < 0)
722 return -EINVAL;
723 if (pos >= available || !count)
724 return 0;
725 if (count > available - pos)
726 count = available - pos;
727 ret = copy_to_user(to, from + pos, count);
728 if (ret == count)
729 return -EFAULT;
730 count -= ret;
731 *ppos = pos + count;
732 return count;
733}
734EXPORT_SYMBOL(simple_read_from_buffer);
735
736/**
737 * simple_write_to_buffer - copy data from user space to the buffer
738 * @to: the buffer to write to
739 * @available: the size of the buffer
740 * @ppos: the current position in the buffer
741 * @from: the user space buffer to read from
742 * @count: the maximum number of bytes to read
743 *
744 * The simple_write_to_buffer() function reads up to @count bytes from the user
745 * space address starting at @from into the buffer @to at offset @ppos.
746 *
747 * On success, the number of bytes written is returned and the offset @ppos is
748 * advanced by this number, or negative value is returned on error.
749 **/
750ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
751 const void __user *from, size_t count)
752{
753 loff_t pos = *ppos;
754 size_t res;
755
756 if (pos < 0)
757 return -EINVAL;
758 if (pos >= available || !count)
759 return 0;
760 if (count > available - pos)
761 count = available - pos;
762 res = copy_from_user(to + pos, from, count);
763 if (res == count)
764 return -EFAULT;
765 count -= res;
766 *ppos = pos + count;
767 return count;
768}
769EXPORT_SYMBOL(simple_write_to_buffer);
770
771/**
772 * memory_read_from_buffer - copy data from the buffer
773 * @to: the kernel space buffer to read to
774 * @count: the maximum number of bytes to read
775 * @ppos: the current position in the buffer
776 * @from: the buffer to read from
777 * @available: the size of the buffer
778 *
779 * The memory_read_from_buffer() function reads up to @count bytes from the
780 * buffer @from at offset @ppos into the kernel space address starting at @to.
781 *
782 * On success, the number of bytes read is returned and the offset @ppos is
783 * advanced by this number, or negative value is returned on error.
784 **/
785ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
786 const void *from, size_t available)
787{
788 loff_t pos = *ppos;
789
790 if (pos < 0)
791 return -EINVAL;
792 if (pos >= available)
793 return 0;
794 if (count > available - pos)
795 count = available - pos;
796 memcpy(to, from + pos, count);
797 *ppos = pos + count;
798
799 return count;
800}
801EXPORT_SYMBOL(memory_read_from_buffer);
802
803/*
804 * Transaction based IO.
805 * The file expects a single write which triggers the transaction, and then
806 * possibly a read which collects the result - which is stored in a
807 * file-local buffer.
808 */
809
810void simple_transaction_set(struct file *file, size_t n)
811{
812 struct simple_transaction_argresp *ar = file->private_data;
813
814 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
815
816 /*
817 * The barrier ensures that ar->size will really remain zero until
818 * ar->data is ready for reading.
819 */
820 smp_mb();
821 ar->size = n;
822}
823EXPORT_SYMBOL(simple_transaction_set);
824
825char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
826{
827 struct simple_transaction_argresp *ar;
828 static DEFINE_SPINLOCK(simple_transaction_lock);
829
830 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
831 return ERR_PTR(-EFBIG);
832
833 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
834 if (!ar)
835 return ERR_PTR(-ENOMEM);
836
837 spin_lock(&simple_transaction_lock);
838
839 /* only one write allowed per open */
840 if (file->private_data) {
841 spin_unlock(&simple_transaction_lock);
842 free_page((unsigned long)ar);
843 return ERR_PTR(-EBUSY);
844 }
845
846 file->private_data = ar;
847
848 spin_unlock(&simple_transaction_lock);
849
850 if (copy_from_user(ar->data, buf, size))
851 return ERR_PTR(-EFAULT);
852
853 return ar->data;
854}
855EXPORT_SYMBOL(simple_transaction_get);
856
857ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
858{
859 struct simple_transaction_argresp *ar = file->private_data;
860
861 if (!ar)
862 return 0;
863 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
864}
865EXPORT_SYMBOL(simple_transaction_read);
866
867int simple_transaction_release(struct inode *inode, struct file *file)
868{
869 free_page((unsigned long)file->private_data);
870 return 0;
871}
872EXPORT_SYMBOL(simple_transaction_release);
873
874/* Simple attribute files */
875
876struct simple_attr {
877 int (*get)(void *, u64 *);
878 int (*set)(void *, u64);
879 char get_buf[24]; /* enough to store a u64 and "\n\0" */
880 char set_buf[24];
881 void *data;
882 const char *fmt; /* format for read operation */
883 struct mutex mutex; /* protects access to these buffers */
884};
885
886/* simple_attr_open is called by an actual attribute open file operation
887 * to set the attribute specific access operations. */
888int simple_attr_open(struct inode *inode, struct file *file,
889 int (*get)(void *, u64 *), int (*set)(void *, u64),
890 const char *fmt)
891{
892 struct simple_attr *attr;
893
894 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
895 if (!attr)
896 return -ENOMEM;
897
898 attr->get = get;
899 attr->set = set;
900 attr->data = inode->i_private;
901 attr->fmt = fmt;
902 mutex_init(&attr->mutex);
903
904 file->private_data = attr;
905
906 return nonseekable_open(inode, file);
907}
908EXPORT_SYMBOL_GPL(simple_attr_open);
909
910int simple_attr_release(struct inode *inode, struct file *file)
911{
912 kfree(file->private_data);
913 return 0;
914}
915EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
916
917/* read from the buffer that is filled with the get function */
918ssize_t simple_attr_read(struct file *file, char __user *buf,
919 size_t len, loff_t *ppos)
920{
921 struct simple_attr *attr;
922 size_t size;
923 ssize_t ret;
924
925 attr = file->private_data;
926
927 if (!attr->get)
928 return -EACCES;
929
930 ret = mutex_lock_interruptible(&attr->mutex);
931 if (ret)
932 return ret;
933
934 if (*ppos && attr->get_buf[0]) {
935 /* continued read */
936 size = strlen(attr->get_buf);
937 } else {
938 /* first read */
939 u64 val;
940 ret = attr->get(attr->data, &val);
941 if (ret)
942 goto out;
943
944 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
945 attr->fmt, (unsigned long long)val);
946 }
947
948 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
949out:
950 mutex_unlock(&attr->mutex);
951 return ret;
952}
953EXPORT_SYMBOL_GPL(simple_attr_read);
954
955/* interpret the buffer as a number to call the set function with */
956ssize_t simple_attr_write(struct file *file, const char __user *buf,
957 size_t len, loff_t *ppos)
958{
959 struct simple_attr *attr;
960 u64 val;
961 size_t size;
962 ssize_t ret;
963
964 attr = file->private_data;
965 if (!attr->set)
966 return -EACCES;
967
968 ret = mutex_lock_interruptible(&attr->mutex);
969 if (ret)
970 return ret;
971
972 ret = -EFAULT;
973 size = min(sizeof(attr->set_buf) - 1, len);
974 if (copy_from_user(attr->set_buf, buf, size))
975 goto out;
976
977 attr->set_buf[size] = '\0';
978 val = simple_strtoll(attr->set_buf, NULL, 0);
979 ret = attr->set(attr->data, val);
980 if (ret == 0)
981 ret = len; /* on success, claim we got the whole input */
982out:
983 mutex_unlock(&attr->mutex);
984 return ret;
985}
986EXPORT_SYMBOL_GPL(simple_attr_write);
987
988/**
989 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
990 * @sb: filesystem to do the file handle conversion on
991 * @fid: file handle to convert
992 * @fh_len: length of the file handle in bytes
993 * @fh_type: type of file handle
994 * @get_inode: filesystem callback to retrieve inode
995 *
996 * This function decodes @fid as long as it has one of the well-known
997 * Linux filehandle types and calls @get_inode on it to retrieve the
998 * inode for the object specified in the file handle.
999 */
1000struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
1001 int fh_len, int fh_type, struct inode *(*get_inode)
1002 (struct super_block *sb, u64 ino, u32 gen))
1003{
1004 struct inode *inode = NULL;
1005
1006 if (fh_len < 2)
1007 return NULL;
1008
1009 switch (fh_type) {
1010 case FILEID_INO32_GEN:
1011 case FILEID_INO32_GEN_PARENT:
1012 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
1013 break;
1014 }
1015
1016 return d_obtain_alias(inode);
1017}
1018EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
1019
1020/**
1021 * generic_fh_to_parent - generic helper for the fh_to_parent export operation
1022 * @sb: filesystem to do the file handle conversion on
1023 * @fid: file handle to convert
1024 * @fh_len: length of the file handle in bytes
1025 * @fh_type: type of file handle
1026 * @get_inode: filesystem callback to retrieve inode
1027 *
1028 * This function decodes @fid as long as it has one of the well-known
1029 * Linux filehandle types and calls @get_inode on it to retrieve the
1030 * inode for the _parent_ object specified in the file handle if it
1031 * is specified in the file handle, or NULL otherwise.
1032 */
1033struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
1034 int fh_len, int fh_type, struct inode *(*get_inode)
1035 (struct super_block *sb, u64 ino, u32 gen))
1036{
1037 struct inode *inode = NULL;
1038
1039 if (fh_len <= 2)
1040 return NULL;
1041
1042 switch (fh_type) {
1043 case FILEID_INO32_GEN_PARENT:
1044 inode = get_inode(sb, fid->i32.parent_ino,
1045 (fh_len > 3 ? fid->i32.parent_gen : 0));
1046 break;
1047 }
1048
1049 return d_obtain_alias(inode);
1050}
1051EXPORT_SYMBOL_GPL(generic_fh_to_parent);
1052
1053/**
1054 * __generic_file_fsync - generic fsync implementation for simple filesystems
1055 *
1056 * @file: file to synchronize
1057 * @start: start offset in bytes
1058 * @end: end offset in bytes (inclusive)
1059 * @datasync: only synchronize essential metadata if true
1060 *
1061 * This is a generic implementation of the fsync method for simple
1062 * filesystems which track all non-inode metadata in the buffers list
1063 * hanging off the address_space structure.
1064 */
1065int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
1066 int datasync)
1067{
1068 struct inode *inode = file->f_mapping->host;
1069 int err;
1070 int ret;
1071
1072 err = file_write_and_wait_range(file, start, end);
1073 if (err)
1074 return err;
1075
1076 inode_lock(inode);
1077 ret = sync_mapping_buffers(inode->i_mapping);
1078 if (!(inode->i_state & I_DIRTY_ALL))
1079 goto out;
1080 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
1081 goto out;
1082
1083 err = sync_inode_metadata(inode, 1);
1084 if (ret == 0)
1085 ret = err;
1086
1087out:
1088 inode_unlock(inode);
1089 /* check and advance again to catch errors after syncing out buffers */
1090 err = file_check_and_advance_wb_err(file);
1091 if (ret == 0)
1092 ret = err;
1093 return ret;
1094}
1095EXPORT_SYMBOL(__generic_file_fsync);
1096
1097/**
1098 * generic_file_fsync - generic fsync implementation for simple filesystems
1099 * with flush
1100 * @file: file to synchronize
1101 * @start: start offset in bytes
1102 * @end: end offset in bytes (inclusive)
1103 * @datasync: only synchronize essential metadata if true
1104 *
1105 */
1106
1107int generic_file_fsync(struct file *file, loff_t start, loff_t end,
1108 int datasync)
1109{
1110 struct inode *inode = file->f_mapping->host;
1111 int err;
1112
1113 err = __generic_file_fsync(file, start, end, datasync);
1114 if (err)
1115 return err;
1116 return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL);
1117}
1118EXPORT_SYMBOL(generic_file_fsync);
1119
1120/**
1121 * generic_check_addressable - Check addressability of file system
1122 * @blocksize_bits: log of file system block size
1123 * @num_blocks: number of blocks in file system
1124 *
1125 * Determine whether a file system with @num_blocks blocks (and a
1126 * block size of 2**@blocksize_bits) is addressable by the sector_t
1127 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
1128 */
1129int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
1130{
1131 u64 last_fs_block = num_blocks - 1;
1132 u64 last_fs_page =
1133 last_fs_block >> (PAGE_SHIFT - blocksize_bits);
1134
1135 if (unlikely(num_blocks == 0))
1136 return 0;
1137
1138 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
1139 return -EINVAL;
1140
1141 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
1142 (last_fs_page > (pgoff_t)(~0ULL))) {
1143 return -EFBIG;
1144 }
1145 return 0;
1146}
1147EXPORT_SYMBOL(generic_check_addressable);
1148
1149/*
1150 * No-op implementation of ->fsync for in-memory filesystems.
1151 */
1152int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1153{
1154 return 0;
1155}
1156EXPORT_SYMBOL(noop_fsync);
1157
1158int noop_set_page_dirty(struct page *page)
1159{
1160 /*
1161 * Unlike __set_page_dirty_no_writeback that handles dirty page
1162 * tracking in the page object, dax does all dirty tracking in
1163 * the inode address_space in response to mkwrite faults. In the
1164 * dax case we only need to worry about potentially dirty CPU
1165 * caches, not dirty page cache pages to write back.
1166 *
1167 * This callback is defined to prevent fallback to
1168 * __set_page_dirty_buffers() in set_page_dirty().
1169 */
1170 return 0;
1171}
1172EXPORT_SYMBOL_GPL(noop_set_page_dirty);
1173
1174void noop_invalidatepage(struct page *page, unsigned int offset,
1175 unsigned int length)
1176{
1177 /*
1178 * There is no page cache to invalidate in the dax case, however
1179 * we need this callback defined to prevent falling back to
1180 * block_invalidatepage() in do_invalidatepage().
1181 */
1182}
1183EXPORT_SYMBOL_GPL(noop_invalidatepage);
1184
1185ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
1186{
1187 /*
1188 * iomap based filesystems support direct I/O without need for
1189 * this callback. However, it still needs to be set in
1190 * inode->a_ops so that open/fcntl know that direct I/O is
1191 * generally supported.
1192 */
1193 return -EINVAL;
1194}
1195EXPORT_SYMBOL_GPL(noop_direct_IO);
1196
1197/* Because kfree isn't assignment-compatible with void(void*) ;-/ */
1198void kfree_link(void *p)
1199{
1200 kfree(p);
1201}
1202EXPORT_SYMBOL(kfree_link);
1203
1204/*
1205 * nop .set_page_dirty method so that people can use .page_mkwrite on
1206 * anon inodes.
1207 */
1208static int anon_set_page_dirty(struct page *page)
1209{
1210 return 0;
1211};
1212
1213/*
1214 * A single inode exists for all anon_inode files. Contrary to pipes,
1215 * anon_inode inodes have no associated per-instance data, so we need
1216 * only allocate one of them.
1217 */
1218struct inode *alloc_anon_inode(struct super_block *s)
1219{
1220 static const struct address_space_operations anon_aops = {
1221 .set_page_dirty = anon_set_page_dirty,
1222 };
1223 struct inode *inode = new_inode_pseudo(s);
1224
1225 if (!inode)
1226 return ERR_PTR(-ENOMEM);
1227
1228 inode->i_ino = get_next_ino();
1229 inode->i_mapping->a_ops = &anon_aops;
1230
1231 /*
1232 * Mark the inode dirty from the very beginning,
1233 * that way it will never be moved to the dirty
1234 * list because mark_inode_dirty() will think
1235 * that it already _is_ on the dirty list.
1236 */
1237 inode->i_state = I_DIRTY;
1238 inode->i_mode = S_IRUSR | S_IWUSR;
1239 inode->i_uid = current_fsuid();
1240 inode->i_gid = current_fsgid();
1241 inode->i_flags |= S_PRIVATE;
1242 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
1243 return inode;
1244}
1245EXPORT_SYMBOL(alloc_anon_inode);
1246
1247/**
1248 * simple_nosetlease - generic helper for prohibiting leases
1249 * @filp: file pointer
1250 * @arg: type of lease to obtain
1251 * @flp: new lease supplied for insertion
1252 * @priv: private data for lm_setup operation
1253 *
1254 * Generic helper for filesystems that do not wish to allow leases to be set.
1255 * All arguments are ignored and it just returns -EINVAL.
1256 */
1257int
1258simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
1259 void **priv)
1260{
1261 return -EINVAL;
1262}
1263EXPORT_SYMBOL(simple_nosetlease);
1264
1265/**
1266 * simple_get_link - generic helper to get the target of "fast" symlinks
1267 * @dentry: not used here
1268 * @inode: the symlink inode
1269 * @done: not used here
1270 *
1271 * Generic helper for filesystems to use for symlink inodes where a pointer to
1272 * the symlink target is stored in ->i_link. NOTE: this isn't normally called,
1273 * since as an optimization the path lookup code uses any non-NULL ->i_link
1274 * directly, without calling ->get_link(). But ->get_link() still must be set,
1275 * to mark the inode_operations as being for a symlink.
1276 *
1277 * Return: the symlink target
1278 */
1279const char *simple_get_link(struct dentry *dentry, struct inode *inode,
1280 struct delayed_call *done)
1281{
1282 return inode->i_link;
1283}
1284EXPORT_SYMBOL(simple_get_link);
1285
1286const struct inode_operations simple_symlink_inode_operations = {
1287 .get_link = simple_get_link,
1288};
1289EXPORT_SYMBOL(simple_symlink_inode_operations);
1290
1291/*
1292 * Operations for a permanently empty directory.
1293 */
1294static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
1295{
1296 return ERR_PTR(-ENOENT);
1297}
1298
1299static int empty_dir_getattr(const struct path *path, struct kstat *stat,
1300 u32 request_mask, unsigned int query_flags)
1301{
1302 struct inode *inode = d_inode(path->dentry);
1303 generic_fillattr(inode, stat);
1304 return 0;
1305}
1306
1307static int empty_dir_setattr(struct dentry *dentry, struct iattr *attr)
1308{
1309 return -EPERM;
1310}
1311
1312static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
1313{
1314 return -EOPNOTSUPP;
1315}
1316
1317static const struct inode_operations empty_dir_inode_operations = {
1318 .lookup = empty_dir_lookup,
1319 .permission = generic_permission,
1320 .setattr = empty_dir_setattr,
1321 .getattr = empty_dir_getattr,
1322 .listxattr = empty_dir_listxattr,
1323};
1324
1325static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
1326{
1327 /* An empty directory has two entries . and .. at offsets 0 and 1 */
1328 return generic_file_llseek_size(file, offset, whence, 2, 2);
1329}
1330
1331static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
1332{
1333 dir_emit_dots(file, ctx);
1334 return 0;
1335}
1336
1337static const struct file_operations empty_dir_operations = {
1338 .llseek = empty_dir_llseek,
1339 .read = generic_read_dir,
1340 .iterate_shared = empty_dir_readdir,
1341 .fsync = noop_fsync,
1342};
1343
1344
1345void make_empty_dir_inode(struct inode *inode)
1346{
1347 set_nlink(inode, 2);
1348 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
1349 inode->i_uid = GLOBAL_ROOT_UID;
1350 inode->i_gid = GLOBAL_ROOT_GID;
1351 inode->i_rdev = 0;
1352 inode->i_size = 0;
1353 inode->i_blkbits = PAGE_SHIFT;
1354 inode->i_blocks = 0;
1355
1356 inode->i_op = &empty_dir_inode_operations;
1357 inode->i_opflags &= ~IOP_XATTR;
1358 inode->i_fop = &empty_dir_operations;
1359}
1360
1361bool is_empty_dir_inode(struct inode *inode)
1362{
1363 return (inode->i_fop == &empty_dir_operations) &&
1364 (inode->i_op == &empty_dir_inode_operations);
1365}