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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/iversion.h>
19#include <linux/writeback.h>
20#include <linux/buffer_head.h> /* sync_mapping_buffers */
21#include <linux/fs_context.h>
22#include <linux/pseudo_fs.h>
23#include <linux/fsnotify.h>
24#include <linux/unicode.h>
25#include <linux/fscrypt.h>
26
27#include <linux/uaccess.h>
28
29#include "internal.h"
30
31int simple_getattr(struct user_namespace *mnt_userns, const struct path *path,
32 struct kstat *stat, u32 request_mask,
33 unsigned int query_flags)
34{
35 struct inode *inode = d_inode(path->dentry);
36 generic_fillattr(&init_user_ns, inode, stat);
37 stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
38 return 0;
39}
40EXPORT_SYMBOL(simple_getattr);
41
42int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
43{
44 buf->f_type = dentry->d_sb->s_magic;
45 buf->f_bsize = PAGE_SIZE;
46 buf->f_namelen = NAME_MAX;
47 return 0;
48}
49EXPORT_SYMBOL(simple_statfs);
50
51/*
52 * Retaining negative dentries for an in-memory filesystem just wastes
53 * memory and lookup time: arrange for them to be deleted immediately.
54 */
55int always_delete_dentry(const struct dentry *dentry)
56{
57 return 1;
58}
59EXPORT_SYMBOL(always_delete_dentry);
60
61const struct dentry_operations simple_dentry_operations = {
62 .d_delete = always_delete_dentry,
63};
64EXPORT_SYMBOL(simple_dentry_operations);
65
66/*
67 * Lookup the data. This is trivial - if the dentry didn't already
68 * exist, we know it is negative. Set d_op to delete negative dentries.
69 */
70struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
71{
72 if (dentry->d_name.len > NAME_MAX)
73 return ERR_PTR(-ENAMETOOLONG);
74 if (!dentry->d_sb->s_d_op)
75 d_set_d_op(dentry, &simple_dentry_operations);
76 d_add(dentry, NULL);
77 return NULL;
78}
79EXPORT_SYMBOL(simple_lookup);
80
81int dcache_dir_open(struct inode *inode, struct file *file)
82{
83 file->private_data = d_alloc_cursor(file->f_path.dentry);
84
85 return file->private_data ? 0 : -ENOMEM;
86}
87EXPORT_SYMBOL(dcache_dir_open);
88
89int dcache_dir_close(struct inode *inode, struct file *file)
90{
91 dput(file->private_data);
92 return 0;
93}
94EXPORT_SYMBOL(dcache_dir_close);
95
96/* parent is locked at least shared */
97/*
98 * Returns an element of siblings' list.
99 * We are looking for <count>th positive after <p>; if
100 * found, dentry is grabbed and returned to caller.
101 * If no such element exists, NULL is returned.
102 */
103static struct dentry *scan_positives(struct dentry *cursor,
104 struct list_head *p,
105 loff_t count,
106 struct dentry *last)
107{
108 struct dentry *dentry = cursor->d_parent, *found = NULL;
109
110 spin_lock(&dentry->d_lock);
111 while ((p = p->next) != &dentry->d_subdirs) {
112 struct dentry *d = list_entry(p, struct dentry, d_child);
113 // we must at least skip cursors, to avoid livelocks
114 if (d->d_flags & DCACHE_DENTRY_CURSOR)
115 continue;
116 if (simple_positive(d) && !--count) {
117 spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
118 if (simple_positive(d))
119 found = dget_dlock(d);
120 spin_unlock(&d->d_lock);
121 if (likely(found))
122 break;
123 count = 1;
124 }
125 if (need_resched()) {
126 list_move(&cursor->d_child, p);
127 p = &cursor->d_child;
128 spin_unlock(&dentry->d_lock);
129 cond_resched();
130 spin_lock(&dentry->d_lock);
131 }
132 }
133 spin_unlock(&dentry->d_lock);
134 dput(last);
135 return found;
136}
137
138loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
139{
140 struct dentry *dentry = file->f_path.dentry;
141 switch (whence) {
142 case 1:
143 offset += file->f_pos;
144 fallthrough;
145 case 0:
146 if (offset >= 0)
147 break;
148 fallthrough;
149 default:
150 return -EINVAL;
151 }
152 if (offset != file->f_pos) {
153 struct dentry *cursor = file->private_data;
154 struct dentry *to = NULL;
155
156 inode_lock_shared(dentry->d_inode);
157
158 if (offset > 2)
159 to = scan_positives(cursor, &dentry->d_subdirs,
160 offset - 2, NULL);
161 spin_lock(&dentry->d_lock);
162 if (to)
163 list_move(&cursor->d_child, &to->d_child);
164 else
165 list_del_init(&cursor->d_child);
166 spin_unlock(&dentry->d_lock);
167 dput(to);
168
169 file->f_pos = offset;
170
171 inode_unlock_shared(dentry->d_inode);
172 }
173 return offset;
174}
175EXPORT_SYMBOL(dcache_dir_lseek);
176
177/* Relationship between i_mode and the DT_xxx types */
178static inline unsigned char dt_type(struct inode *inode)
179{
180 return (inode->i_mode >> 12) & 15;
181}
182
183/*
184 * Directory is locked and all positive dentries in it are safe, since
185 * for ramfs-type trees they can't go away without unlink() or rmdir(),
186 * both impossible due to the lock on directory.
187 */
188
189int dcache_readdir(struct file *file, struct dir_context *ctx)
190{
191 struct dentry *dentry = file->f_path.dentry;
192 struct dentry *cursor = file->private_data;
193 struct list_head *anchor = &dentry->d_subdirs;
194 struct dentry *next = NULL;
195 struct list_head *p;
196
197 if (!dir_emit_dots(file, ctx))
198 return 0;
199
200 if (ctx->pos == 2)
201 p = anchor;
202 else if (!list_empty(&cursor->d_child))
203 p = &cursor->d_child;
204 else
205 return 0;
206
207 while ((next = scan_positives(cursor, p, 1, next)) != NULL) {
208 if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
209 d_inode(next)->i_ino, dt_type(d_inode(next))))
210 break;
211 ctx->pos++;
212 p = &next->d_child;
213 }
214 spin_lock(&dentry->d_lock);
215 if (next)
216 list_move_tail(&cursor->d_child, &next->d_child);
217 else
218 list_del_init(&cursor->d_child);
219 spin_unlock(&dentry->d_lock);
220 dput(next);
221
222 return 0;
223}
224EXPORT_SYMBOL(dcache_readdir);
225
226ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
227{
228 return -EISDIR;
229}
230EXPORT_SYMBOL(generic_read_dir);
231
232const struct file_operations simple_dir_operations = {
233 .open = dcache_dir_open,
234 .release = dcache_dir_close,
235 .llseek = dcache_dir_lseek,
236 .read = generic_read_dir,
237 .iterate_shared = dcache_readdir,
238 .fsync = noop_fsync,
239};
240EXPORT_SYMBOL(simple_dir_operations);
241
242const struct inode_operations simple_dir_inode_operations = {
243 .lookup = simple_lookup,
244};
245EXPORT_SYMBOL(simple_dir_inode_operations);
246
247static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev)
248{
249 struct dentry *child = NULL;
250 struct list_head *p = prev ? &prev->d_child : &parent->d_subdirs;
251
252 spin_lock(&parent->d_lock);
253 while ((p = p->next) != &parent->d_subdirs) {
254 struct dentry *d = container_of(p, struct dentry, d_child);
255 if (simple_positive(d)) {
256 spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
257 if (simple_positive(d))
258 child = dget_dlock(d);
259 spin_unlock(&d->d_lock);
260 if (likely(child))
261 break;
262 }
263 }
264 spin_unlock(&parent->d_lock);
265 dput(prev);
266 return child;
267}
268
269void simple_recursive_removal(struct dentry *dentry,
270 void (*callback)(struct dentry *))
271{
272 struct dentry *this = dget(dentry);
273 while (true) {
274 struct dentry *victim = NULL, *child;
275 struct inode *inode = this->d_inode;
276
277 inode_lock(inode);
278 if (d_is_dir(this))
279 inode->i_flags |= S_DEAD;
280 while ((child = find_next_child(this, victim)) == NULL) {
281 // kill and ascend
282 // update metadata while it's still locked
283 inode->i_ctime = current_time(inode);
284 clear_nlink(inode);
285 inode_unlock(inode);
286 victim = this;
287 this = this->d_parent;
288 inode = this->d_inode;
289 inode_lock(inode);
290 if (simple_positive(victim)) {
291 d_invalidate(victim); // avoid lost mounts
292 if (d_is_dir(victim))
293 fsnotify_rmdir(inode, victim);
294 else
295 fsnotify_unlink(inode, victim);
296 if (callback)
297 callback(victim);
298 dput(victim); // unpin it
299 }
300 if (victim == dentry) {
301 inode->i_ctime = inode->i_mtime =
302 current_time(inode);
303 if (d_is_dir(dentry))
304 drop_nlink(inode);
305 inode_unlock(inode);
306 dput(dentry);
307 return;
308 }
309 }
310 inode_unlock(inode);
311 this = child;
312 }
313}
314EXPORT_SYMBOL(simple_recursive_removal);
315
316static const struct super_operations simple_super_operations = {
317 .statfs = simple_statfs,
318};
319
320static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc)
321{
322 struct pseudo_fs_context *ctx = fc->fs_private;
323 struct inode *root;
324
325 s->s_maxbytes = MAX_LFS_FILESIZE;
326 s->s_blocksize = PAGE_SIZE;
327 s->s_blocksize_bits = PAGE_SHIFT;
328 s->s_magic = ctx->magic;
329 s->s_op = ctx->ops ?: &simple_super_operations;
330 s->s_xattr = ctx->xattr;
331 s->s_time_gran = 1;
332 root = new_inode(s);
333 if (!root)
334 return -ENOMEM;
335
336 /*
337 * since this is the first inode, make it number 1. New inodes created
338 * after this must take care not to collide with it (by passing
339 * max_reserved of 1 to iunique).
340 */
341 root->i_ino = 1;
342 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
343 root->i_atime = root->i_mtime = root->i_ctime = current_time(root);
344 s->s_root = d_make_root(root);
345 if (!s->s_root)
346 return -ENOMEM;
347 s->s_d_op = ctx->dops;
348 return 0;
349}
350
351static int pseudo_fs_get_tree(struct fs_context *fc)
352{
353 return get_tree_nodev(fc, pseudo_fs_fill_super);
354}
355
356static void pseudo_fs_free(struct fs_context *fc)
357{
358 kfree(fc->fs_private);
359}
360
361static const struct fs_context_operations pseudo_fs_context_ops = {
362 .free = pseudo_fs_free,
363 .get_tree = pseudo_fs_get_tree,
364};
365
366/*
367 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
368 * will never be mountable)
369 */
370struct pseudo_fs_context *init_pseudo(struct fs_context *fc,
371 unsigned long magic)
372{
373 struct pseudo_fs_context *ctx;
374
375 ctx = kzalloc(sizeof(struct pseudo_fs_context), GFP_KERNEL);
376 if (likely(ctx)) {
377 ctx->magic = magic;
378 fc->fs_private = ctx;
379 fc->ops = &pseudo_fs_context_ops;
380 fc->sb_flags |= SB_NOUSER;
381 fc->global = true;
382 }
383 return ctx;
384}
385EXPORT_SYMBOL(init_pseudo);
386
387int simple_open(struct inode *inode, struct file *file)
388{
389 if (inode->i_private)
390 file->private_data = inode->i_private;
391 return 0;
392}
393EXPORT_SYMBOL(simple_open);
394
395int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
396{
397 struct inode *inode = d_inode(old_dentry);
398
399 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
400 inc_nlink(inode);
401 ihold(inode);
402 dget(dentry);
403 d_instantiate(dentry, inode);
404 return 0;
405}
406EXPORT_SYMBOL(simple_link);
407
408int simple_empty(struct dentry *dentry)
409{
410 struct dentry *child;
411 int ret = 0;
412
413 spin_lock(&dentry->d_lock);
414 list_for_each_entry(child, &dentry->d_subdirs, d_child) {
415 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
416 if (simple_positive(child)) {
417 spin_unlock(&child->d_lock);
418 goto out;
419 }
420 spin_unlock(&child->d_lock);
421 }
422 ret = 1;
423out:
424 spin_unlock(&dentry->d_lock);
425 return ret;
426}
427EXPORT_SYMBOL(simple_empty);
428
429int simple_unlink(struct inode *dir, struct dentry *dentry)
430{
431 struct inode *inode = d_inode(dentry);
432
433 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
434 drop_nlink(inode);
435 dput(dentry);
436 return 0;
437}
438EXPORT_SYMBOL(simple_unlink);
439
440int simple_rmdir(struct inode *dir, struct dentry *dentry)
441{
442 if (!simple_empty(dentry))
443 return -ENOTEMPTY;
444
445 drop_nlink(d_inode(dentry));
446 simple_unlink(dir, dentry);
447 drop_nlink(dir);
448 return 0;
449}
450EXPORT_SYMBOL(simple_rmdir);
451
452int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry,
453 struct inode *new_dir, struct dentry *new_dentry)
454{
455 bool old_is_dir = d_is_dir(old_dentry);
456 bool new_is_dir = d_is_dir(new_dentry);
457
458 if (old_dir != new_dir && old_is_dir != new_is_dir) {
459 if (old_is_dir) {
460 drop_nlink(old_dir);
461 inc_nlink(new_dir);
462 } else {
463 drop_nlink(new_dir);
464 inc_nlink(old_dir);
465 }
466 }
467 old_dir->i_ctime = old_dir->i_mtime =
468 new_dir->i_ctime = new_dir->i_mtime =
469 d_inode(old_dentry)->i_ctime =
470 d_inode(new_dentry)->i_ctime = current_time(old_dir);
471
472 return 0;
473}
474EXPORT_SYMBOL_GPL(simple_rename_exchange);
475
476int simple_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
477 struct dentry *old_dentry, struct inode *new_dir,
478 struct dentry *new_dentry, unsigned int flags)
479{
480 struct inode *inode = d_inode(old_dentry);
481 int they_are_dirs = d_is_dir(old_dentry);
482
483 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
484 return -EINVAL;
485
486 if (flags & RENAME_EXCHANGE)
487 return simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
488
489 if (!simple_empty(new_dentry))
490 return -ENOTEMPTY;
491
492 if (d_really_is_positive(new_dentry)) {
493 simple_unlink(new_dir, new_dentry);
494 if (they_are_dirs) {
495 drop_nlink(d_inode(new_dentry));
496 drop_nlink(old_dir);
497 }
498 } else if (they_are_dirs) {
499 drop_nlink(old_dir);
500 inc_nlink(new_dir);
501 }
502
503 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
504 new_dir->i_mtime = inode->i_ctime = current_time(old_dir);
505
506 return 0;
507}
508EXPORT_SYMBOL(simple_rename);
509
510/**
511 * simple_setattr - setattr for simple filesystem
512 * @mnt_userns: user namespace of the target mount
513 * @dentry: dentry
514 * @iattr: iattr structure
515 *
516 * Returns 0 on success, -error on failure.
517 *
518 * simple_setattr is a simple ->setattr implementation without a proper
519 * implementation of size changes.
520 *
521 * It can either be used for in-memory filesystems or special files
522 * on simple regular filesystems. Anything that needs to change on-disk
523 * or wire state on size changes needs its own setattr method.
524 */
525int simple_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
526 struct iattr *iattr)
527{
528 struct inode *inode = d_inode(dentry);
529 int error;
530
531 error = setattr_prepare(mnt_userns, dentry, iattr);
532 if (error)
533 return error;
534
535 if (iattr->ia_valid & ATTR_SIZE)
536 truncate_setsize(inode, iattr->ia_size);
537 setattr_copy(mnt_userns, inode, iattr);
538 mark_inode_dirty(inode);
539 return 0;
540}
541EXPORT_SYMBOL(simple_setattr);
542
543static int simple_read_folio(struct file *file, struct folio *folio)
544{
545 folio_zero_range(folio, 0, folio_size(folio));
546 flush_dcache_folio(folio);
547 folio_mark_uptodate(folio);
548 folio_unlock(folio);
549 return 0;
550}
551
552int simple_write_begin(struct file *file, struct address_space *mapping,
553 loff_t pos, unsigned len,
554 struct page **pagep, void **fsdata)
555{
556 struct page *page;
557 pgoff_t index;
558
559 index = pos >> PAGE_SHIFT;
560
561 page = grab_cache_page_write_begin(mapping, index);
562 if (!page)
563 return -ENOMEM;
564
565 *pagep = page;
566
567 if (!PageUptodate(page) && (len != PAGE_SIZE)) {
568 unsigned from = pos & (PAGE_SIZE - 1);
569
570 zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
571 }
572 return 0;
573}
574EXPORT_SYMBOL(simple_write_begin);
575
576/**
577 * simple_write_end - .write_end helper for non-block-device FSes
578 * @file: See .write_end of address_space_operations
579 * @mapping: "
580 * @pos: "
581 * @len: "
582 * @copied: "
583 * @page: "
584 * @fsdata: "
585 *
586 * simple_write_end does the minimum needed for updating a page after writing is
587 * done. It has the same API signature as the .write_end of
588 * address_space_operations vector. So it can just be set onto .write_end for
589 * FSes that don't need any other processing. i_mutex is assumed to be held.
590 * Block based filesystems should use generic_write_end().
591 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
592 * is not called, so a filesystem that actually does store data in .write_inode
593 * should extend on what's done here with a call to mark_inode_dirty() in the
594 * case that i_size has changed.
595 *
596 * Use *ONLY* with simple_read_folio()
597 */
598static int simple_write_end(struct file *file, struct address_space *mapping,
599 loff_t pos, unsigned len, unsigned copied,
600 struct page *page, void *fsdata)
601{
602 struct inode *inode = page->mapping->host;
603 loff_t last_pos = pos + copied;
604
605 /* zero the stale part of the page if we did a short copy */
606 if (!PageUptodate(page)) {
607 if (copied < len) {
608 unsigned from = pos & (PAGE_SIZE - 1);
609
610 zero_user(page, from + copied, len - copied);
611 }
612 SetPageUptodate(page);
613 }
614 /*
615 * No need to use i_size_read() here, the i_size
616 * cannot change under us because we hold the i_mutex.
617 */
618 if (last_pos > inode->i_size)
619 i_size_write(inode, last_pos);
620
621 set_page_dirty(page);
622 unlock_page(page);
623 put_page(page);
624
625 return copied;
626}
627
628/*
629 * Provides ramfs-style behavior: data in the pagecache, but no writeback.
630 */
631const struct address_space_operations ram_aops = {
632 .read_folio = simple_read_folio,
633 .write_begin = simple_write_begin,
634 .write_end = simple_write_end,
635 .dirty_folio = noop_dirty_folio,
636};
637EXPORT_SYMBOL(ram_aops);
638
639/*
640 * the inodes created here are not hashed. If you use iunique to generate
641 * unique inode values later for this filesystem, then you must take care
642 * to pass it an appropriate max_reserved value to avoid collisions.
643 */
644int simple_fill_super(struct super_block *s, unsigned long magic,
645 const struct tree_descr *files)
646{
647 struct inode *inode;
648 struct dentry *root;
649 struct dentry *dentry;
650 int i;
651
652 s->s_blocksize = PAGE_SIZE;
653 s->s_blocksize_bits = PAGE_SHIFT;
654 s->s_magic = magic;
655 s->s_op = &simple_super_operations;
656 s->s_time_gran = 1;
657
658 inode = new_inode(s);
659 if (!inode)
660 return -ENOMEM;
661 /*
662 * because the root inode is 1, the files array must not contain an
663 * entry at index 1
664 */
665 inode->i_ino = 1;
666 inode->i_mode = S_IFDIR | 0755;
667 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
668 inode->i_op = &simple_dir_inode_operations;
669 inode->i_fop = &simple_dir_operations;
670 set_nlink(inode, 2);
671 root = d_make_root(inode);
672 if (!root)
673 return -ENOMEM;
674 for (i = 0; !files->name || files->name[0]; i++, files++) {
675 if (!files->name)
676 continue;
677
678 /* warn if it tries to conflict with the root inode */
679 if (unlikely(i == 1))
680 printk(KERN_WARNING "%s: %s passed in a files array"
681 "with an index of 1!\n", __func__,
682 s->s_type->name);
683
684 dentry = d_alloc_name(root, files->name);
685 if (!dentry)
686 goto out;
687 inode = new_inode(s);
688 if (!inode) {
689 dput(dentry);
690 goto out;
691 }
692 inode->i_mode = S_IFREG | files->mode;
693 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
694 inode->i_fop = files->ops;
695 inode->i_ino = i;
696 d_add(dentry, inode);
697 }
698 s->s_root = root;
699 return 0;
700out:
701 d_genocide(root);
702 shrink_dcache_parent(root);
703 dput(root);
704 return -ENOMEM;
705}
706EXPORT_SYMBOL(simple_fill_super);
707
708static DEFINE_SPINLOCK(pin_fs_lock);
709
710int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
711{
712 struct vfsmount *mnt = NULL;
713 spin_lock(&pin_fs_lock);
714 if (unlikely(!*mount)) {
715 spin_unlock(&pin_fs_lock);
716 mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
717 if (IS_ERR(mnt))
718 return PTR_ERR(mnt);
719 spin_lock(&pin_fs_lock);
720 if (!*mount)
721 *mount = mnt;
722 }
723 mntget(*mount);
724 ++*count;
725 spin_unlock(&pin_fs_lock);
726 mntput(mnt);
727 return 0;
728}
729EXPORT_SYMBOL(simple_pin_fs);
730
731void simple_release_fs(struct vfsmount **mount, int *count)
732{
733 struct vfsmount *mnt;
734 spin_lock(&pin_fs_lock);
735 mnt = *mount;
736 if (!--*count)
737 *mount = NULL;
738 spin_unlock(&pin_fs_lock);
739 mntput(mnt);
740}
741EXPORT_SYMBOL(simple_release_fs);
742
743/**
744 * simple_read_from_buffer - copy data from the buffer to user space
745 * @to: the user space buffer to read to
746 * @count: the maximum number of bytes to read
747 * @ppos: the current position in the buffer
748 * @from: the buffer to read from
749 * @available: the size of the buffer
750 *
751 * The simple_read_from_buffer() function reads up to @count bytes from the
752 * buffer @from at offset @ppos into the user space address starting at @to.
753 *
754 * On success, the number of bytes read is returned and the offset @ppos is
755 * advanced by this number, or negative value is returned on error.
756 **/
757ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
758 const void *from, size_t available)
759{
760 loff_t pos = *ppos;
761 size_t ret;
762
763 if (pos < 0)
764 return -EINVAL;
765 if (pos >= available || !count)
766 return 0;
767 if (count > available - pos)
768 count = available - pos;
769 ret = copy_to_user(to, from + pos, count);
770 if (ret == count)
771 return -EFAULT;
772 count -= ret;
773 *ppos = pos + count;
774 return count;
775}
776EXPORT_SYMBOL(simple_read_from_buffer);
777
778/**
779 * simple_write_to_buffer - copy data from user space to the buffer
780 * @to: the buffer to write to
781 * @available: the size of the buffer
782 * @ppos: the current position in the buffer
783 * @from: the user space buffer to read from
784 * @count: the maximum number of bytes to read
785 *
786 * The simple_write_to_buffer() function reads up to @count bytes from the user
787 * space address starting at @from into the buffer @to at offset @ppos.
788 *
789 * On success, the number of bytes written is returned and the offset @ppos is
790 * advanced by this number, or negative value is returned on error.
791 **/
792ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
793 const void __user *from, size_t count)
794{
795 loff_t pos = *ppos;
796 size_t res;
797
798 if (pos < 0)
799 return -EINVAL;
800 if (pos >= available || !count)
801 return 0;
802 if (count > available - pos)
803 count = available - pos;
804 res = copy_from_user(to + pos, from, count);
805 if (res == count)
806 return -EFAULT;
807 count -= res;
808 *ppos = pos + count;
809 return count;
810}
811EXPORT_SYMBOL(simple_write_to_buffer);
812
813/**
814 * memory_read_from_buffer - copy data from the buffer
815 * @to: the kernel space buffer to read to
816 * @count: the maximum number of bytes to read
817 * @ppos: the current position in the buffer
818 * @from: the buffer to read from
819 * @available: the size of the buffer
820 *
821 * The memory_read_from_buffer() function reads up to @count bytes from the
822 * buffer @from at offset @ppos into the kernel space address starting at @to.
823 *
824 * On success, the number of bytes read is returned and the offset @ppos is
825 * advanced by this number, or negative value is returned on error.
826 **/
827ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
828 const void *from, size_t available)
829{
830 loff_t pos = *ppos;
831
832 if (pos < 0)
833 return -EINVAL;
834 if (pos >= available)
835 return 0;
836 if (count > available - pos)
837 count = available - pos;
838 memcpy(to, from + pos, count);
839 *ppos = pos + count;
840
841 return count;
842}
843EXPORT_SYMBOL(memory_read_from_buffer);
844
845/*
846 * Transaction based IO.
847 * The file expects a single write which triggers the transaction, and then
848 * possibly a read which collects the result - which is stored in a
849 * file-local buffer.
850 */
851
852void simple_transaction_set(struct file *file, size_t n)
853{
854 struct simple_transaction_argresp *ar = file->private_data;
855
856 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
857
858 /*
859 * The barrier ensures that ar->size will really remain zero until
860 * ar->data is ready for reading.
861 */
862 smp_mb();
863 ar->size = n;
864}
865EXPORT_SYMBOL(simple_transaction_set);
866
867char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
868{
869 struct simple_transaction_argresp *ar;
870 static DEFINE_SPINLOCK(simple_transaction_lock);
871
872 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
873 return ERR_PTR(-EFBIG);
874
875 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
876 if (!ar)
877 return ERR_PTR(-ENOMEM);
878
879 spin_lock(&simple_transaction_lock);
880
881 /* only one write allowed per open */
882 if (file->private_data) {
883 spin_unlock(&simple_transaction_lock);
884 free_page((unsigned long)ar);
885 return ERR_PTR(-EBUSY);
886 }
887
888 file->private_data = ar;
889
890 spin_unlock(&simple_transaction_lock);
891
892 if (copy_from_user(ar->data, buf, size))
893 return ERR_PTR(-EFAULT);
894
895 return ar->data;
896}
897EXPORT_SYMBOL(simple_transaction_get);
898
899ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
900{
901 struct simple_transaction_argresp *ar = file->private_data;
902
903 if (!ar)
904 return 0;
905 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
906}
907EXPORT_SYMBOL(simple_transaction_read);
908
909int simple_transaction_release(struct inode *inode, struct file *file)
910{
911 free_page((unsigned long)file->private_data);
912 return 0;
913}
914EXPORT_SYMBOL(simple_transaction_release);
915
916/* Simple attribute files */
917
918struct simple_attr {
919 int (*get)(void *, u64 *);
920 int (*set)(void *, u64);
921 char get_buf[24]; /* enough to store a u64 and "\n\0" */
922 char set_buf[24];
923 void *data;
924 const char *fmt; /* format for read operation */
925 struct mutex mutex; /* protects access to these buffers */
926};
927
928/* simple_attr_open is called by an actual attribute open file operation
929 * to set the attribute specific access operations. */
930int simple_attr_open(struct inode *inode, struct file *file,
931 int (*get)(void *, u64 *), int (*set)(void *, u64),
932 const char *fmt)
933{
934 struct simple_attr *attr;
935
936 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
937 if (!attr)
938 return -ENOMEM;
939
940 attr->get = get;
941 attr->set = set;
942 attr->data = inode->i_private;
943 attr->fmt = fmt;
944 mutex_init(&attr->mutex);
945
946 file->private_data = attr;
947
948 return nonseekable_open(inode, file);
949}
950EXPORT_SYMBOL_GPL(simple_attr_open);
951
952int simple_attr_release(struct inode *inode, struct file *file)
953{
954 kfree(file->private_data);
955 return 0;
956}
957EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
958
959/* read from the buffer that is filled with the get function */
960ssize_t simple_attr_read(struct file *file, char __user *buf,
961 size_t len, loff_t *ppos)
962{
963 struct simple_attr *attr;
964 size_t size;
965 ssize_t ret;
966
967 attr = file->private_data;
968
969 if (!attr->get)
970 return -EACCES;
971
972 ret = mutex_lock_interruptible(&attr->mutex);
973 if (ret)
974 return ret;
975
976 if (*ppos && attr->get_buf[0]) {
977 /* continued read */
978 size = strlen(attr->get_buf);
979 } else {
980 /* first read */
981 u64 val;
982 ret = attr->get(attr->data, &val);
983 if (ret)
984 goto out;
985
986 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
987 attr->fmt, (unsigned long long)val);
988 }
989
990 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
991out:
992 mutex_unlock(&attr->mutex);
993 return ret;
994}
995EXPORT_SYMBOL_GPL(simple_attr_read);
996
997/* interpret the buffer as a number to call the set function with */
998static ssize_t simple_attr_write_xsigned(struct file *file, const char __user *buf,
999 size_t len, loff_t *ppos, bool is_signed)
1000{
1001 struct simple_attr *attr;
1002 unsigned long long val;
1003 size_t size;
1004 ssize_t ret;
1005
1006 attr = file->private_data;
1007 if (!attr->set)
1008 return -EACCES;
1009
1010 ret = mutex_lock_interruptible(&attr->mutex);
1011 if (ret)
1012 return ret;
1013
1014 ret = -EFAULT;
1015 size = min(sizeof(attr->set_buf) - 1, len);
1016 if (copy_from_user(attr->set_buf, buf, size))
1017 goto out;
1018
1019 attr->set_buf[size] = '\0';
1020 if (is_signed)
1021 ret = kstrtoll(attr->set_buf, 0, &val);
1022 else
1023 ret = kstrtoull(attr->set_buf, 0, &val);
1024 if (ret)
1025 goto out;
1026 ret = attr->set(attr->data, val);
1027 if (ret == 0)
1028 ret = len; /* on success, claim we got the whole input */
1029out:
1030 mutex_unlock(&attr->mutex);
1031 return ret;
1032}
1033
1034ssize_t simple_attr_write(struct file *file, const char __user *buf,
1035 size_t len, loff_t *ppos)
1036{
1037 return simple_attr_write_xsigned(file, buf, len, ppos, false);
1038}
1039EXPORT_SYMBOL_GPL(simple_attr_write);
1040
1041ssize_t simple_attr_write_signed(struct file *file, const char __user *buf,
1042 size_t len, loff_t *ppos)
1043{
1044 return simple_attr_write_xsigned(file, buf, len, ppos, true);
1045}
1046EXPORT_SYMBOL_GPL(simple_attr_write_signed);
1047
1048/**
1049 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
1050 * @sb: filesystem to do the file handle conversion on
1051 * @fid: file handle to convert
1052 * @fh_len: length of the file handle in bytes
1053 * @fh_type: type of file handle
1054 * @get_inode: filesystem callback to retrieve inode
1055 *
1056 * This function decodes @fid as long as it has one of the well-known
1057 * Linux filehandle types and calls @get_inode on it to retrieve the
1058 * inode for the object specified in the file handle.
1059 */
1060struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
1061 int fh_len, int fh_type, struct inode *(*get_inode)
1062 (struct super_block *sb, u64 ino, u32 gen))
1063{
1064 struct inode *inode = NULL;
1065
1066 if (fh_len < 2)
1067 return NULL;
1068
1069 switch (fh_type) {
1070 case FILEID_INO32_GEN:
1071 case FILEID_INO32_GEN_PARENT:
1072 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
1073 break;
1074 }
1075
1076 return d_obtain_alias(inode);
1077}
1078EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
1079
1080/**
1081 * generic_fh_to_parent - generic helper for the fh_to_parent export operation
1082 * @sb: filesystem to do the file handle conversion on
1083 * @fid: file handle to convert
1084 * @fh_len: length of the file handle in bytes
1085 * @fh_type: type of file handle
1086 * @get_inode: filesystem callback to retrieve inode
1087 *
1088 * This function decodes @fid as long as it has one of the well-known
1089 * Linux filehandle types and calls @get_inode on it to retrieve the
1090 * inode for the _parent_ object specified in the file handle if it
1091 * is specified in the file handle, or NULL otherwise.
1092 */
1093struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
1094 int fh_len, int fh_type, struct inode *(*get_inode)
1095 (struct super_block *sb, u64 ino, u32 gen))
1096{
1097 struct inode *inode = NULL;
1098
1099 if (fh_len <= 2)
1100 return NULL;
1101
1102 switch (fh_type) {
1103 case FILEID_INO32_GEN_PARENT:
1104 inode = get_inode(sb, fid->i32.parent_ino,
1105 (fh_len > 3 ? fid->i32.parent_gen : 0));
1106 break;
1107 }
1108
1109 return d_obtain_alias(inode);
1110}
1111EXPORT_SYMBOL_GPL(generic_fh_to_parent);
1112
1113/**
1114 * __generic_file_fsync - generic fsync implementation for simple filesystems
1115 *
1116 * @file: file to synchronize
1117 * @start: start offset in bytes
1118 * @end: end offset in bytes (inclusive)
1119 * @datasync: only synchronize essential metadata if true
1120 *
1121 * This is a generic implementation of the fsync method for simple
1122 * filesystems which track all non-inode metadata in the buffers list
1123 * hanging off the address_space structure.
1124 */
1125int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
1126 int datasync)
1127{
1128 struct inode *inode = file->f_mapping->host;
1129 int err;
1130 int ret;
1131
1132 err = file_write_and_wait_range(file, start, end);
1133 if (err)
1134 return err;
1135
1136 inode_lock(inode);
1137 ret = sync_mapping_buffers(inode->i_mapping);
1138 if (!(inode->i_state & I_DIRTY_ALL))
1139 goto out;
1140 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
1141 goto out;
1142
1143 err = sync_inode_metadata(inode, 1);
1144 if (ret == 0)
1145 ret = err;
1146
1147out:
1148 inode_unlock(inode);
1149 /* check and advance again to catch errors after syncing out buffers */
1150 err = file_check_and_advance_wb_err(file);
1151 if (ret == 0)
1152 ret = err;
1153 return ret;
1154}
1155EXPORT_SYMBOL(__generic_file_fsync);
1156
1157/**
1158 * generic_file_fsync - generic fsync implementation for simple filesystems
1159 * with flush
1160 * @file: file to synchronize
1161 * @start: start offset in bytes
1162 * @end: end offset in bytes (inclusive)
1163 * @datasync: only synchronize essential metadata if true
1164 *
1165 */
1166
1167int generic_file_fsync(struct file *file, loff_t start, loff_t end,
1168 int datasync)
1169{
1170 struct inode *inode = file->f_mapping->host;
1171 int err;
1172
1173 err = __generic_file_fsync(file, start, end, datasync);
1174 if (err)
1175 return err;
1176 return blkdev_issue_flush(inode->i_sb->s_bdev);
1177}
1178EXPORT_SYMBOL(generic_file_fsync);
1179
1180/**
1181 * generic_check_addressable - Check addressability of file system
1182 * @blocksize_bits: log of file system block size
1183 * @num_blocks: number of blocks in file system
1184 *
1185 * Determine whether a file system with @num_blocks blocks (and a
1186 * block size of 2**@blocksize_bits) is addressable by the sector_t
1187 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
1188 */
1189int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
1190{
1191 u64 last_fs_block = num_blocks - 1;
1192 u64 last_fs_page =
1193 last_fs_block >> (PAGE_SHIFT - blocksize_bits);
1194
1195 if (unlikely(num_blocks == 0))
1196 return 0;
1197
1198 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
1199 return -EINVAL;
1200
1201 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
1202 (last_fs_page > (pgoff_t)(~0ULL))) {
1203 return -EFBIG;
1204 }
1205 return 0;
1206}
1207EXPORT_SYMBOL(generic_check_addressable);
1208
1209/*
1210 * No-op implementation of ->fsync for in-memory filesystems.
1211 */
1212int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1213{
1214 return 0;
1215}
1216EXPORT_SYMBOL(noop_fsync);
1217
1218ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
1219{
1220 /*
1221 * iomap based filesystems support direct I/O without need for
1222 * this callback. However, it still needs to be set in
1223 * inode->a_ops so that open/fcntl know that direct I/O is
1224 * generally supported.
1225 */
1226 return -EINVAL;
1227}
1228EXPORT_SYMBOL_GPL(noop_direct_IO);
1229
1230/* Because kfree isn't assignment-compatible with void(void*) ;-/ */
1231void kfree_link(void *p)
1232{
1233 kfree(p);
1234}
1235EXPORT_SYMBOL(kfree_link);
1236
1237struct inode *alloc_anon_inode(struct super_block *s)
1238{
1239 static const struct address_space_operations anon_aops = {
1240 .dirty_folio = noop_dirty_folio,
1241 };
1242 struct inode *inode = new_inode_pseudo(s);
1243
1244 if (!inode)
1245 return ERR_PTR(-ENOMEM);
1246
1247 inode->i_ino = get_next_ino();
1248 inode->i_mapping->a_ops = &anon_aops;
1249
1250 /*
1251 * Mark the inode dirty from the very beginning,
1252 * that way it will never be moved to the dirty
1253 * list because mark_inode_dirty() will think
1254 * that it already _is_ on the dirty list.
1255 */
1256 inode->i_state = I_DIRTY;
1257 inode->i_mode = S_IRUSR | S_IWUSR;
1258 inode->i_uid = current_fsuid();
1259 inode->i_gid = current_fsgid();
1260 inode->i_flags |= S_PRIVATE;
1261 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
1262 return inode;
1263}
1264EXPORT_SYMBOL(alloc_anon_inode);
1265
1266/**
1267 * simple_nosetlease - generic helper for prohibiting leases
1268 * @filp: file pointer
1269 * @arg: type of lease to obtain
1270 * @flp: new lease supplied for insertion
1271 * @priv: private data for lm_setup operation
1272 *
1273 * Generic helper for filesystems that do not wish to allow leases to be set.
1274 * All arguments are ignored and it just returns -EINVAL.
1275 */
1276int
1277simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
1278 void **priv)
1279{
1280 return -EINVAL;
1281}
1282EXPORT_SYMBOL(simple_nosetlease);
1283
1284/**
1285 * simple_get_link - generic helper to get the target of "fast" symlinks
1286 * @dentry: not used here
1287 * @inode: the symlink inode
1288 * @done: not used here
1289 *
1290 * Generic helper for filesystems to use for symlink inodes where a pointer to
1291 * the symlink target is stored in ->i_link. NOTE: this isn't normally called,
1292 * since as an optimization the path lookup code uses any non-NULL ->i_link
1293 * directly, without calling ->get_link(). But ->get_link() still must be set,
1294 * to mark the inode_operations as being for a symlink.
1295 *
1296 * Return: the symlink target
1297 */
1298const char *simple_get_link(struct dentry *dentry, struct inode *inode,
1299 struct delayed_call *done)
1300{
1301 return inode->i_link;
1302}
1303EXPORT_SYMBOL(simple_get_link);
1304
1305const struct inode_operations simple_symlink_inode_operations = {
1306 .get_link = simple_get_link,
1307};
1308EXPORT_SYMBOL(simple_symlink_inode_operations);
1309
1310/*
1311 * Operations for a permanently empty directory.
1312 */
1313static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
1314{
1315 return ERR_PTR(-ENOENT);
1316}
1317
1318static int empty_dir_getattr(struct user_namespace *mnt_userns,
1319 const struct path *path, struct kstat *stat,
1320 u32 request_mask, unsigned int query_flags)
1321{
1322 struct inode *inode = d_inode(path->dentry);
1323 generic_fillattr(&init_user_ns, inode, stat);
1324 return 0;
1325}
1326
1327static int empty_dir_setattr(struct user_namespace *mnt_userns,
1328 struct dentry *dentry, struct iattr *attr)
1329{
1330 return -EPERM;
1331}
1332
1333static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
1334{
1335 return -EOPNOTSUPP;
1336}
1337
1338static const struct inode_operations empty_dir_inode_operations = {
1339 .lookup = empty_dir_lookup,
1340 .permission = generic_permission,
1341 .setattr = empty_dir_setattr,
1342 .getattr = empty_dir_getattr,
1343 .listxattr = empty_dir_listxattr,
1344};
1345
1346static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
1347{
1348 /* An empty directory has two entries . and .. at offsets 0 and 1 */
1349 return generic_file_llseek_size(file, offset, whence, 2, 2);
1350}
1351
1352static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
1353{
1354 dir_emit_dots(file, ctx);
1355 return 0;
1356}
1357
1358static const struct file_operations empty_dir_operations = {
1359 .llseek = empty_dir_llseek,
1360 .read = generic_read_dir,
1361 .iterate_shared = empty_dir_readdir,
1362 .fsync = noop_fsync,
1363};
1364
1365
1366void make_empty_dir_inode(struct inode *inode)
1367{
1368 set_nlink(inode, 2);
1369 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
1370 inode->i_uid = GLOBAL_ROOT_UID;
1371 inode->i_gid = GLOBAL_ROOT_GID;
1372 inode->i_rdev = 0;
1373 inode->i_size = 0;
1374 inode->i_blkbits = PAGE_SHIFT;
1375 inode->i_blocks = 0;
1376
1377 inode->i_op = &empty_dir_inode_operations;
1378 inode->i_opflags &= ~IOP_XATTR;
1379 inode->i_fop = &empty_dir_operations;
1380}
1381
1382bool is_empty_dir_inode(struct inode *inode)
1383{
1384 return (inode->i_fop == &empty_dir_operations) &&
1385 (inode->i_op == &empty_dir_inode_operations);
1386}
1387
1388#if IS_ENABLED(CONFIG_UNICODE)
1389/*
1390 * Determine if the name of a dentry should be casefolded.
1391 *
1392 * Return: if names will need casefolding
1393 */
1394static bool needs_casefold(const struct inode *dir)
1395{
1396 return IS_CASEFOLDED(dir) && dir->i_sb->s_encoding;
1397}
1398
1399/**
1400 * generic_ci_d_compare - generic d_compare implementation for casefolding filesystems
1401 * @dentry: dentry whose name we are checking against
1402 * @len: len of name of dentry
1403 * @str: str pointer to name of dentry
1404 * @name: Name to compare against
1405 *
1406 * Return: 0 if names match, 1 if mismatch, or -ERRNO
1407 */
1408static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
1409 const char *str, const struct qstr *name)
1410{
1411 const struct dentry *parent = READ_ONCE(dentry->d_parent);
1412 const struct inode *dir = READ_ONCE(parent->d_inode);
1413 const struct super_block *sb = dentry->d_sb;
1414 const struct unicode_map *um = sb->s_encoding;
1415 struct qstr qstr = QSTR_INIT(str, len);
1416 char strbuf[DNAME_INLINE_LEN];
1417 int ret;
1418
1419 if (!dir || !needs_casefold(dir))
1420 goto fallback;
1421 /*
1422 * If the dentry name is stored in-line, then it may be concurrently
1423 * modified by a rename. If this happens, the VFS will eventually retry
1424 * the lookup, so it doesn't matter what ->d_compare() returns.
1425 * However, it's unsafe to call utf8_strncasecmp() with an unstable
1426 * string. Therefore, we have to copy the name into a temporary buffer.
1427 */
1428 if (len <= DNAME_INLINE_LEN - 1) {
1429 memcpy(strbuf, str, len);
1430 strbuf[len] = 0;
1431 qstr.name = strbuf;
1432 /* prevent compiler from optimizing out the temporary buffer */
1433 barrier();
1434 }
1435 ret = utf8_strncasecmp(um, name, &qstr);
1436 if (ret >= 0)
1437 return ret;
1438
1439 if (sb_has_strict_encoding(sb))
1440 return -EINVAL;
1441fallback:
1442 if (len != name->len)
1443 return 1;
1444 return !!memcmp(str, name->name, len);
1445}
1446
1447/**
1448 * generic_ci_d_hash - generic d_hash implementation for casefolding filesystems
1449 * @dentry: dentry of the parent directory
1450 * @str: qstr of name whose hash we should fill in
1451 *
1452 * Return: 0 if hash was successful or unchanged, and -EINVAL on error
1453 */
1454static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
1455{
1456 const struct inode *dir = READ_ONCE(dentry->d_inode);
1457 struct super_block *sb = dentry->d_sb;
1458 const struct unicode_map *um = sb->s_encoding;
1459 int ret = 0;
1460
1461 if (!dir || !needs_casefold(dir))
1462 return 0;
1463
1464 ret = utf8_casefold_hash(um, dentry, str);
1465 if (ret < 0 && sb_has_strict_encoding(sb))
1466 return -EINVAL;
1467 return 0;
1468}
1469
1470static const struct dentry_operations generic_ci_dentry_ops = {
1471 .d_hash = generic_ci_d_hash,
1472 .d_compare = generic_ci_d_compare,
1473};
1474#endif
1475
1476#ifdef CONFIG_FS_ENCRYPTION
1477static const struct dentry_operations generic_encrypted_dentry_ops = {
1478 .d_revalidate = fscrypt_d_revalidate,
1479};
1480#endif
1481
1482#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
1483static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
1484 .d_hash = generic_ci_d_hash,
1485 .d_compare = generic_ci_d_compare,
1486 .d_revalidate = fscrypt_d_revalidate,
1487};
1488#endif
1489
1490/**
1491 * generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry
1492 * @dentry: dentry to set ops on
1493 *
1494 * Casefolded directories need d_hash and d_compare set, so that the dentries
1495 * contained in them are handled case-insensitively. Note that these operations
1496 * are needed on the parent directory rather than on the dentries in it, and
1497 * while the casefolding flag can be toggled on and off on an empty directory,
1498 * dentry_operations can't be changed later. As a result, if the filesystem has
1499 * casefolding support enabled at all, we have to give all dentries the
1500 * casefolding operations even if their inode doesn't have the casefolding flag
1501 * currently (and thus the casefolding ops would be no-ops for now).
1502 *
1503 * Encryption works differently in that the only dentry operation it needs is
1504 * d_revalidate, which it only needs on dentries that have the no-key name flag.
1505 * The no-key flag can't be set "later", so we don't have to worry about that.
1506 *
1507 * Finally, to maximize compatibility with overlayfs (which isn't compatible
1508 * with certain dentry operations) and to avoid taking an unnecessary
1509 * performance hit, we use custom dentry_operations for each possible
1510 * combination rather than always installing all operations.
1511 */
1512void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
1513{
1514#ifdef CONFIG_FS_ENCRYPTION
1515 bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME;
1516#endif
1517#if IS_ENABLED(CONFIG_UNICODE)
1518 bool needs_ci_ops = dentry->d_sb->s_encoding;
1519#endif
1520#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
1521 if (needs_encrypt_ops && needs_ci_ops) {
1522 d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
1523 return;
1524 }
1525#endif
1526#ifdef CONFIG_FS_ENCRYPTION
1527 if (needs_encrypt_ops) {
1528 d_set_d_op(dentry, &generic_encrypted_dentry_ops);
1529 return;
1530 }
1531#endif
1532#if IS_ENABLED(CONFIG_UNICODE)
1533 if (needs_ci_ops) {
1534 d_set_d_op(dentry, &generic_ci_dentry_ops);
1535 return;
1536 }
1537#endif
1538}
1539EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);
1540
1541/**
1542 * inode_maybe_inc_iversion - increments i_version
1543 * @inode: inode with the i_version that should be updated
1544 * @force: increment the counter even if it's not necessary?
1545 *
1546 * Every time the inode is modified, the i_version field must be seen to have
1547 * changed by any observer.
1548 *
1549 * If "force" is set or the QUERIED flag is set, then ensure that we increment
1550 * the value, and clear the queried flag.
1551 *
1552 * In the common case where neither is set, then we can return "false" without
1553 * updating i_version.
1554 *
1555 * If this function returns false, and no other metadata has changed, then we
1556 * can avoid logging the metadata.
1557 */
1558bool inode_maybe_inc_iversion(struct inode *inode, bool force)
1559{
1560 u64 cur, new;
1561
1562 /*
1563 * The i_version field is not strictly ordered with any other inode
1564 * information, but the legacy inode_inc_iversion code used a spinlock
1565 * to serialize increments.
1566 *
1567 * Here, we add full memory barriers to ensure that any de-facto
1568 * ordering with other info is preserved.
1569 *
1570 * This barrier pairs with the barrier in inode_query_iversion()
1571 */
1572 smp_mb();
1573 cur = inode_peek_iversion_raw(inode);
1574 do {
1575 /* If flag is clear then we needn't do anything */
1576 if (!force && !(cur & I_VERSION_QUERIED))
1577 return false;
1578
1579 /* Since lowest bit is flag, add 2 to avoid it */
1580 new = (cur & ~I_VERSION_QUERIED) + I_VERSION_INCREMENT;
1581 } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new));
1582 return true;
1583}
1584EXPORT_SYMBOL(inode_maybe_inc_iversion);
1/*
2 * fs/libfs.c
3 * Library for filesystems writers.
4 */
5
6#include <linux/blkdev.h>
7#include <linux/export.h>
8#include <linux/pagemap.h>
9#include <linux/slab.h>
10#include <linux/cred.h>
11#include <linux/mount.h>
12#include <linux/vfs.h>
13#include <linux/quotaops.h>
14#include <linux/mutex.h>
15#include <linux/namei.h>
16#include <linux/exportfs.h>
17#include <linux/writeback.h>
18#include <linux/buffer_head.h> /* sync_mapping_buffers */
19
20#include <linux/uaccess.h>
21
22#include "internal.h"
23
24int simple_getattr(const struct path *path, struct kstat *stat,
25 u32 request_mask, unsigned int query_flags)
26{
27 struct inode *inode = d_inode(path->dentry);
28 generic_fillattr(inode, stat);
29 stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
30 return 0;
31}
32EXPORT_SYMBOL(simple_getattr);
33
34int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
35{
36 buf->f_type = dentry->d_sb->s_magic;
37 buf->f_bsize = PAGE_SIZE;
38 buf->f_namelen = NAME_MAX;
39 return 0;
40}
41EXPORT_SYMBOL(simple_statfs);
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 */
47int always_delete_dentry(const struct dentry *dentry)
48{
49 return 1;
50}
51EXPORT_SYMBOL(always_delete_dentry);
52
53const struct dentry_operations simple_dentry_operations = {
54 .d_delete = always_delete_dentry,
55};
56EXPORT_SYMBOL(simple_dentry_operations);
57
58/*
59 * Lookup the data. This is trivial - if the dentry didn't already
60 * exist, we know it is negative. Set d_op to delete negative dentries.
61 */
62struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
63{
64 if (dentry->d_name.len > NAME_MAX)
65 return ERR_PTR(-ENAMETOOLONG);
66 if (!dentry->d_sb->s_d_op)
67 d_set_d_op(dentry, &simple_dentry_operations);
68 d_add(dentry, NULL);
69 return NULL;
70}
71EXPORT_SYMBOL(simple_lookup);
72
73int dcache_dir_open(struct inode *inode, struct file *file)
74{
75 file->private_data = d_alloc_cursor(file->f_path.dentry);
76
77 return file->private_data ? 0 : -ENOMEM;
78}
79EXPORT_SYMBOL(dcache_dir_open);
80
81int dcache_dir_close(struct inode *inode, struct file *file)
82{
83 dput(file->private_data);
84 return 0;
85}
86EXPORT_SYMBOL(dcache_dir_close);
87
88/* parent is locked at least shared */
89static struct dentry *next_positive(struct dentry *parent,
90 struct list_head *from,
91 int count)
92{
93 unsigned *seq = &parent->d_inode->i_dir_seq, n;
94 struct dentry *res;
95 struct list_head *p;
96 bool skipped;
97 int i;
98
99retry:
100 i = count;
101 skipped = false;
102 n = smp_load_acquire(seq) & ~1;
103 res = NULL;
104 rcu_read_lock();
105 for (p = from->next; p != &parent->d_subdirs; p = p->next) {
106 struct dentry *d = list_entry(p, struct dentry, d_child);
107 if (!simple_positive(d)) {
108 skipped = true;
109 } else if (!--i) {
110 res = d;
111 break;
112 }
113 }
114 rcu_read_unlock();
115 if (skipped) {
116 smp_rmb();
117 if (unlikely(*seq != n))
118 goto retry;
119 }
120 return res;
121}
122
123static void move_cursor(struct dentry *cursor, struct list_head *after)
124{
125 struct dentry *parent = cursor->d_parent;
126 unsigned n, *seq = &parent->d_inode->i_dir_seq;
127 spin_lock(&parent->d_lock);
128 for (;;) {
129 n = *seq;
130 if (!(n & 1) && cmpxchg(seq, n, n + 1) == n)
131 break;
132 cpu_relax();
133 }
134 __list_del(cursor->d_child.prev, cursor->d_child.next);
135 if (after)
136 list_add(&cursor->d_child, after);
137 else
138 list_add_tail(&cursor->d_child, &parent->d_subdirs);
139 smp_store_release(seq, n + 2);
140 spin_unlock(&parent->d_lock);
141}
142
143loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
144{
145 struct dentry *dentry = file->f_path.dentry;
146 switch (whence) {
147 case 1:
148 offset += file->f_pos;
149 case 0:
150 if (offset >= 0)
151 break;
152 default:
153 return -EINVAL;
154 }
155 if (offset != file->f_pos) {
156 file->f_pos = offset;
157 if (file->f_pos >= 2) {
158 struct dentry *cursor = file->private_data;
159 struct dentry *to;
160 loff_t n = file->f_pos - 2;
161
162 inode_lock_shared(dentry->d_inode);
163 to = next_positive(dentry, &dentry->d_subdirs, n);
164 move_cursor(cursor, to ? &to->d_child : NULL);
165 inode_unlock_shared(dentry->d_inode);
166 }
167 }
168 return offset;
169}
170EXPORT_SYMBOL(dcache_dir_lseek);
171
172/* Relationship between i_mode and the DT_xxx types */
173static inline unsigned char dt_type(struct inode *inode)
174{
175 return (inode->i_mode >> 12) & 15;
176}
177
178/*
179 * Directory is locked and all positive dentries in it are safe, since
180 * for ramfs-type trees they can't go away without unlink() or rmdir(),
181 * both impossible due to the lock on directory.
182 */
183
184int dcache_readdir(struct file *file, struct dir_context *ctx)
185{
186 struct dentry *dentry = file->f_path.dentry;
187 struct dentry *cursor = file->private_data;
188 struct list_head *p = &cursor->d_child;
189 struct dentry *next;
190 bool moved = false;
191
192 if (!dir_emit_dots(file, ctx))
193 return 0;
194
195 if (ctx->pos == 2)
196 p = &dentry->d_subdirs;
197 while ((next = next_positive(dentry, p, 1)) != NULL) {
198 if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
199 d_inode(next)->i_ino, dt_type(d_inode(next))))
200 break;
201 moved = true;
202 p = &next->d_child;
203 ctx->pos++;
204 }
205 if (moved)
206 move_cursor(cursor, p);
207 return 0;
208}
209EXPORT_SYMBOL(dcache_readdir);
210
211ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
212{
213 return -EISDIR;
214}
215EXPORT_SYMBOL(generic_read_dir);
216
217const struct file_operations simple_dir_operations = {
218 .open = dcache_dir_open,
219 .release = dcache_dir_close,
220 .llseek = dcache_dir_lseek,
221 .read = generic_read_dir,
222 .iterate_shared = dcache_readdir,
223 .fsync = noop_fsync,
224};
225EXPORT_SYMBOL(simple_dir_operations);
226
227const struct inode_operations simple_dir_inode_operations = {
228 .lookup = simple_lookup,
229};
230EXPORT_SYMBOL(simple_dir_inode_operations);
231
232static const struct super_operations simple_super_operations = {
233 .statfs = simple_statfs,
234};
235
236/*
237 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
238 * will never be mountable)
239 */
240struct dentry *mount_pseudo_xattr(struct file_system_type *fs_type, char *name,
241 const struct super_operations *ops, const struct xattr_handler **xattr,
242 const struct dentry_operations *dops, unsigned long magic)
243{
244 struct super_block *s;
245 struct dentry *dentry;
246 struct inode *root;
247 struct qstr d_name = QSTR_INIT(name, strlen(name));
248
249 s = sget_userns(fs_type, NULL, set_anon_super, SB_KERNMOUNT|SB_NOUSER,
250 &init_user_ns, NULL);
251 if (IS_ERR(s))
252 return ERR_CAST(s);
253
254 s->s_maxbytes = MAX_LFS_FILESIZE;
255 s->s_blocksize = PAGE_SIZE;
256 s->s_blocksize_bits = PAGE_SHIFT;
257 s->s_magic = magic;
258 s->s_op = ops ? ops : &simple_super_operations;
259 s->s_xattr = xattr;
260 s->s_time_gran = 1;
261 root = new_inode(s);
262 if (!root)
263 goto Enomem;
264 /*
265 * since this is the first inode, make it number 1. New inodes created
266 * after this must take care not to collide with it (by passing
267 * max_reserved of 1 to iunique).
268 */
269 root->i_ino = 1;
270 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
271 root->i_atime = root->i_mtime = root->i_ctime = current_time(root);
272 dentry = __d_alloc(s, &d_name);
273 if (!dentry) {
274 iput(root);
275 goto Enomem;
276 }
277 d_instantiate(dentry, root);
278 s->s_root = dentry;
279 s->s_d_op = dops;
280 s->s_flags |= SB_ACTIVE;
281 return dget(s->s_root);
282
283Enomem:
284 deactivate_locked_super(s);
285 return ERR_PTR(-ENOMEM);
286}
287EXPORT_SYMBOL(mount_pseudo_xattr);
288
289int simple_open(struct inode *inode, struct file *file)
290{
291 if (inode->i_private)
292 file->private_data = inode->i_private;
293 return 0;
294}
295EXPORT_SYMBOL(simple_open);
296
297int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
298{
299 struct inode *inode = d_inode(old_dentry);
300
301 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
302 inc_nlink(inode);
303 ihold(inode);
304 dget(dentry);
305 d_instantiate(dentry, inode);
306 return 0;
307}
308EXPORT_SYMBOL(simple_link);
309
310int simple_empty(struct dentry *dentry)
311{
312 struct dentry *child;
313 int ret = 0;
314
315 spin_lock(&dentry->d_lock);
316 list_for_each_entry(child, &dentry->d_subdirs, d_child) {
317 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
318 if (simple_positive(child)) {
319 spin_unlock(&child->d_lock);
320 goto out;
321 }
322 spin_unlock(&child->d_lock);
323 }
324 ret = 1;
325out:
326 spin_unlock(&dentry->d_lock);
327 return ret;
328}
329EXPORT_SYMBOL(simple_empty);
330
331int simple_unlink(struct inode *dir, struct dentry *dentry)
332{
333 struct inode *inode = d_inode(dentry);
334
335 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
336 drop_nlink(inode);
337 dput(dentry);
338 return 0;
339}
340EXPORT_SYMBOL(simple_unlink);
341
342int simple_rmdir(struct inode *dir, struct dentry *dentry)
343{
344 if (!simple_empty(dentry))
345 return -ENOTEMPTY;
346
347 drop_nlink(d_inode(dentry));
348 simple_unlink(dir, dentry);
349 drop_nlink(dir);
350 return 0;
351}
352EXPORT_SYMBOL(simple_rmdir);
353
354int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
355 struct inode *new_dir, struct dentry *new_dentry,
356 unsigned int flags)
357{
358 struct inode *inode = d_inode(old_dentry);
359 int they_are_dirs = d_is_dir(old_dentry);
360
361 if (flags & ~RENAME_NOREPLACE)
362 return -EINVAL;
363
364 if (!simple_empty(new_dentry))
365 return -ENOTEMPTY;
366
367 if (d_really_is_positive(new_dentry)) {
368 simple_unlink(new_dir, new_dentry);
369 if (they_are_dirs) {
370 drop_nlink(d_inode(new_dentry));
371 drop_nlink(old_dir);
372 }
373 } else if (they_are_dirs) {
374 drop_nlink(old_dir);
375 inc_nlink(new_dir);
376 }
377
378 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
379 new_dir->i_mtime = inode->i_ctime = current_time(old_dir);
380
381 return 0;
382}
383EXPORT_SYMBOL(simple_rename);
384
385/**
386 * simple_setattr - setattr for simple filesystem
387 * @dentry: dentry
388 * @iattr: iattr structure
389 *
390 * Returns 0 on success, -error on failure.
391 *
392 * simple_setattr is a simple ->setattr implementation without a proper
393 * implementation of size changes.
394 *
395 * It can either be used for in-memory filesystems or special files
396 * on simple regular filesystems. Anything that needs to change on-disk
397 * or wire state on size changes needs its own setattr method.
398 */
399int simple_setattr(struct dentry *dentry, struct iattr *iattr)
400{
401 struct inode *inode = d_inode(dentry);
402 int error;
403
404 error = setattr_prepare(dentry, iattr);
405 if (error)
406 return error;
407
408 if (iattr->ia_valid & ATTR_SIZE)
409 truncate_setsize(inode, iattr->ia_size);
410 setattr_copy(inode, iattr);
411 mark_inode_dirty(inode);
412 return 0;
413}
414EXPORT_SYMBOL(simple_setattr);
415
416int simple_readpage(struct file *file, struct page *page)
417{
418 clear_highpage(page);
419 flush_dcache_page(page);
420 SetPageUptodate(page);
421 unlock_page(page);
422 return 0;
423}
424EXPORT_SYMBOL(simple_readpage);
425
426int simple_write_begin(struct file *file, struct address_space *mapping,
427 loff_t pos, unsigned len, unsigned flags,
428 struct page **pagep, void **fsdata)
429{
430 struct page *page;
431 pgoff_t index;
432
433 index = pos >> PAGE_SHIFT;
434
435 page = grab_cache_page_write_begin(mapping, index, flags);
436 if (!page)
437 return -ENOMEM;
438
439 *pagep = page;
440
441 if (!PageUptodate(page) && (len != PAGE_SIZE)) {
442 unsigned from = pos & (PAGE_SIZE - 1);
443
444 zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
445 }
446 return 0;
447}
448EXPORT_SYMBOL(simple_write_begin);
449
450/**
451 * simple_write_end - .write_end helper for non-block-device FSes
452 * @available: See .write_end of address_space_operations
453 * @file: "
454 * @mapping: "
455 * @pos: "
456 * @len: "
457 * @copied: "
458 * @page: "
459 * @fsdata: "
460 *
461 * simple_write_end does the minimum needed for updating a page after writing is
462 * done. It has the same API signature as the .write_end of
463 * address_space_operations vector. So it can just be set onto .write_end for
464 * FSes that don't need any other processing. i_mutex is assumed to be held.
465 * Block based filesystems should use generic_write_end().
466 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
467 * is not called, so a filesystem that actually does store data in .write_inode
468 * should extend on what's done here with a call to mark_inode_dirty() in the
469 * case that i_size has changed.
470 *
471 * Use *ONLY* with simple_readpage()
472 */
473int simple_write_end(struct file *file, struct address_space *mapping,
474 loff_t pos, unsigned len, unsigned copied,
475 struct page *page, void *fsdata)
476{
477 struct inode *inode = page->mapping->host;
478 loff_t last_pos = pos + copied;
479
480 /* zero the stale part of the page if we did a short copy */
481 if (!PageUptodate(page)) {
482 if (copied < len) {
483 unsigned from = pos & (PAGE_SIZE - 1);
484
485 zero_user(page, from + copied, len - copied);
486 }
487 SetPageUptodate(page);
488 }
489 /*
490 * No need to use i_size_read() here, the i_size
491 * cannot change under us because we hold the i_mutex.
492 */
493 if (last_pos > inode->i_size)
494 i_size_write(inode, last_pos);
495
496 set_page_dirty(page);
497 unlock_page(page);
498 put_page(page);
499
500 return copied;
501}
502EXPORT_SYMBOL(simple_write_end);
503
504/*
505 * the inodes created here are not hashed. If you use iunique to generate
506 * unique inode values later for this filesystem, then you must take care
507 * to pass it an appropriate max_reserved value to avoid collisions.
508 */
509int simple_fill_super(struct super_block *s, unsigned long magic,
510 const struct tree_descr *files)
511{
512 struct inode *inode;
513 struct dentry *root;
514 struct dentry *dentry;
515 int i;
516
517 s->s_blocksize = PAGE_SIZE;
518 s->s_blocksize_bits = PAGE_SHIFT;
519 s->s_magic = magic;
520 s->s_op = &simple_super_operations;
521 s->s_time_gran = 1;
522
523 inode = new_inode(s);
524 if (!inode)
525 return -ENOMEM;
526 /*
527 * because the root inode is 1, the files array must not contain an
528 * entry at index 1
529 */
530 inode->i_ino = 1;
531 inode->i_mode = S_IFDIR | 0755;
532 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
533 inode->i_op = &simple_dir_inode_operations;
534 inode->i_fop = &simple_dir_operations;
535 set_nlink(inode, 2);
536 root = d_make_root(inode);
537 if (!root)
538 return -ENOMEM;
539 for (i = 0; !files->name || files->name[0]; i++, files++) {
540 if (!files->name)
541 continue;
542
543 /* warn if it tries to conflict with the root inode */
544 if (unlikely(i == 1))
545 printk(KERN_WARNING "%s: %s passed in a files array"
546 "with an index of 1!\n", __func__,
547 s->s_type->name);
548
549 dentry = d_alloc_name(root, files->name);
550 if (!dentry)
551 goto out;
552 inode = new_inode(s);
553 if (!inode) {
554 dput(dentry);
555 goto out;
556 }
557 inode->i_mode = S_IFREG | files->mode;
558 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
559 inode->i_fop = files->ops;
560 inode->i_ino = i;
561 d_add(dentry, inode);
562 }
563 s->s_root = root;
564 return 0;
565out:
566 d_genocide(root);
567 shrink_dcache_parent(root);
568 dput(root);
569 return -ENOMEM;
570}
571EXPORT_SYMBOL(simple_fill_super);
572
573static DEFINE_SPINLOCK(pin_fs_lock);
574
575int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
576{
577 struct vfsmount *mnt = NULL;
578 spin_lock(&pin_fs_lock);
579 if (unlikely(!*mount)) {
580 spin_unlock(&pin_fs_lock);
581 mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
582 if (IS_ERR(mnt))
583 return PTR_ERR(mnt);
584 spin_lock(&pin_fs_lock);
585 if (!*mount)
586 *mount = mnt;
587 }
588 mntget(*mount);
589 ++*count;
590 spin_unlock(&pin_fs_lock);
591 mntput(mnt);
592 return 0;
593}
594EXPORT_SYMBOL(simple_pin_fs);
595
596void simple_release_fs(struct vfsmount **mount, int *count)
597{
598 struct vfsmount *mnt;
599 spin_lock(&pin_fs_lock);
600 mnt = *mount;
601 if (!--*count)
602 *mount = NULL;
603 spin_unlock(&pin_fs_lock);
604 mntput(mnt);
605}
606EXPORT_SYMBOL(simple_release_fs);
607
608/**
609 * simple_read_from_buffer - copy data from the buffer to user space
610 * @to: the user space buffer to read to
611 * @count: the maximum number of bytes to read
612 * @ppos: the current position in the buffer
613 * @from: the buffer to read from
614 * @available: the size of the buffer
615 *
616 * The simple_read_from_buffer() function reads up to @count bytes from the
617 * buffer @from at offset @ppos into the user space address starting at @to.
618 *
619 * On success, the number of bytes read is returned and the offset @ppos is
620 * advanced by this number, or negative value is returned on error.
621 **/
622ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
623 const void *from, size_t available)
624{
625 loff_t pos = *ppos;
626 size_t ret;
627
628 if (pos < 0)
629 return -EINVAL;
630 if (pos >= available || !count)
631 return 0;
632 if (count > available - pos)
633 count = available - pos;
634 ret = copy_to_user(to, from + pos, count);
635 if (ret == count)
636 return -EFAULT;
637 count -= ret;
638 *ppos = pos + count;
639 return count;
640}
641EXPORT_SYMBOL(simple_read_from_buffer);
642
643/**
644 * simple_write_to_buffer - copy data from user space to the buffer
645 * @to: the buffer to write to
646 * @available: the size of the buffer
647 * @ppos: the current position in the buffer
648 * @from: the user space buffer to read from
649 * @count: the maximum number of bytes to read
650 *
651 * The simple_write_to_buffer() function reads up to @count bytes from the user
652 * space address starting at @from into the buffer @to at offset @ppos.
653 *
654 * On success, the number of bytes written is returned and the offset @ppos is
655 * advanced by this number, or negative value is returned on error.
656 **/
657ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
658 const void __user *from, size_t count)
659{
660 loff_t pos = *ppos;
661 size_t res;
662
663 if (pos < 0)
664 return -EINVAL;
665 if (pos >= available || !count)
666 return 0;
667 if (count > available - pos)
668 count = available - pos;
669 res = copy_from_user(to + pos, from, count);
670 if (res == count)
671 return -EFAULT;
672 count -= res;
673 *ppos = pos + count;
674 return count;
675}
676EXPORT_SYMBOL(simple_write_to_buffer);
677
678/**
679 * memory_read_from_buffer - copy data from the buffer
680 * @to: the kernel space buffer to read to
681 * @count: the maximum number of bytes to read
682 * @ppos: the current position in the buffer
683 * @from: the buffer to read from
684 * @available: the size of the buffer
685 *
686 * The memory_read_from_buffer() function reads up to @count bytes from the
687 * buffer @from at offset @ppos into the kernel space address starting at @to.
688 *
689 * On success, the number of bytes read is returned and the offset @ppos is
690 * advanced by this number, or negative value is returned on error.
691 **/
692ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
693 const void *from, size_t available)
694{
695 loff_t pos = *ppos;
696
697 if (pos < 0)
698 return -EINVAL;
699 if (pos >= available)
700 return 0;
701 if (count > available - pos)
702 count = available - pos;
703 memcpy(to, from + pos, count);
704 *ppos = pos + count;
705
706 return count;
707}
708EXPORT_SYMBOL(memory_read_from_buffer);
709
710/*
711 * Transaction based IO.
712 * The file expects a single write which triggers the transaction, and then
713 * possibly a read which collects the result - which is stored in a
714 * file-local buffer.
715 */
716
717void simple_transaction_set(struct file *file, size_t n)
718{
719 struct simple_transaction_argresp *ar = file->private_data;
720
721 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
722
723 /*
724 * The barrier ensures that ar->size will really remain zero until
725 * ar->data is ready for reading.
726 */
727 smp_mb();
728 ar->size = n;
729}
730EXPORT_SYMBOL(simple_transaction_set);
731
732char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
733{
734 struct simple_transaction_argresp *ar;
735 static DEFINE_SPINLOCK(simple_transaction_lock);
736
737 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
738 return ERR_PTR(-EFBIG);
739
740 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
741 if (!ar)
742 return ERR_PTR(-ENOMEM);
743
744 spin_lock(&simple_transaction_lock);
745
746 /* only one write allowed per open */
747 if (file->private_data) {
748 spin_unlock(&simple_transaction_lock);
749 free_page((unsigned long)ar);
750 return ERR_PTR(-EBUSY);
751 }
752
753 file->private_data = ar;
754
755 spin_unlock(&simple_transaction_lock);
756
757 if (copy_from_user(ar->data, buf, size))
758 return ERR_PTR(-EFAULT);
759
760 return ar->data;
761}
762EXPORT_SYMBOL(simple_transaction_get);
763
764ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
765{
766 struct simple_transaction_argresp *ar = file->private_data;
767
768 if (!ar)
769 return 0;
770 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
771}
772EXPORT_SYMBOL(simple_transaction_read);
773
774int simple_transaction_release(struct inode *inode, struct file *file)
775{
776 free_page((unsigned long)file->private_data);
777 return 0;
778}
779EXPORT_SYMBOL(simple_transaction_release);
780
781/* Simple attribute files */
782
783struct simple_attr {
784 int (*get)(void *, u64 *);
785 int (*set)(void *, u64);
786 char get_buf[24]; /* enough to store a u64 and "\n\0" */
787 char set_buf[24];
788 void *data;
789 const char *fmt; /* format for read operation */
790 struct mutex mutex; /* protects access to these buffers */
791};
792
793/* simple_attr_open is called by an actual attribute open file operation
794 * to set the attribute specific access operations. */
795int simple_attr_open(struct inode *inode, struct file *file,
796 int (*get)(void *, u64 *), int (*set)(void *, u64),
797 const char *fmt)
798{
799 struct simple_attr *attr;
800
801 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
802 if (!attr)
803 return -ENOMEM;
804
805 attr->get = get;
806 attr->set = set;
807 attr->data = inode->i_private;
808 attr->fmt = fmt;
809 mutex_init(&attr->mutex);
810
811 file->private_data = attr;
812
813 return nonseekable_open(inode, file);
814}
815EXPORT_SYMBOL_GPL(simple_attr_open);
816
817int simple_attr_release(struct inode *inode, struct file *file)
818{
819 kfree(file->private_data);
820 return 0;
821}
822EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
823
824/* read from the buffer that is filled with the get function */
825ssize_t simple_attr_read(struct file *file, char __user *buf,
826 size_t len, loff_t *ppos)
827{
828 struct simple_attr *attr;
829 size_t size;
830 ssize_t ret;
831
832 attr = file->private_data;
833
834 if (!attr->get)
835 return -EACCES;
836
837 ret = mutex_lock_interruptible(&attr->mutex);
838 if (ret)
839 return ret;
840
841 if (*ppos) { /* continued read */
842 size = strlen(attr->get_buf);
843 } else { /* first read */
844 u64 val;
845 ret = attr->get(attr->data, &val);
846 if (ret)
847 goto out;
848
849 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
850 attr->fmt, (unsigned long long)val);
851 }
852
853 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
854out:
855 mutex_unlock(&attr->mutex);
856 return ret;
857}
858EXPORT_SYMBOL_GPL(simple_attr_read);
859
860/* interpret the buffer as a number to call the set function with */
861ssize_t simple_attr_write(struct file *file, const char __user *buf,
862 size_t len, loff_t *ppos)
863{
864 struct simple_attr *attr;
865 u64 val;
866 size_t size;
867 ssize_t ret;
868
869 attr = file->private_data;
870 if (!attr->set)
871 return -EACCES;
872
873 ret = mutex_lock_interruptible(&attr->mutex);
874 if (ret)
875 return ret;
876
877 ret = -EFAULT;
878 size = min(sizeof(attr->set_buf) - 1, len);
879 if (copy_from_user(attr->set_buf, buf, size))
880 goto out;
881
882 attr->set_buf[size] = '\0';
883 val = simple_strtoll(attr->set_buf, NULL, 0);
884 ret = attr->set(attr->data, val);
885 if (ret == 0)
886 ret = len; /* on success, claim we got the whole input */
887out:
888 mutex_unlock(&attr->mutex);
889 return ret;
890}
891EXPORT_SYMBOL_GPL(simple_attr_write);
892
893/**
894 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
895 * @sb: filesystem to do the file handle conversion on
896 * @fid: file handle to convert
897 * @fh_len: length of the file handle in bytes
898 * @fh_type: type of file handle
899 * @get_inode: filesystem callback to retrieve inode
900 *
901 * This function decodes @fid as long as it has one of the well-known
902 * Linux filehandle types and calls @get_inode on it to retrieve the
903 * inode for the object specified in the file handle.
904 */
905struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
906 int fh_len, int fh_type, struct inode *(*get_inode)
907 (struct super_block *sb, u64 ino, u32 gen))
908{
909 struct inode *inode = NULL;
910
911 if (fh_len < 2)
912 return NULL;
913
914 switch (fh_type) {
915 case FILEID_INO32_GEN:
916 case FILEID_INO32_GEN_PARENT:
917 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
918 break;
919 }
920
921 return d_obtain_alias(inode);
922}
923EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
924
925/**
926 * generic_fh_to_parent - generic helper for the fh_to_parent export operation
927 * @sb: filesystem to do the file handle conversion on
928 * @fid: file handle to convert
929 * @fh_len: length of the file handle in bytes
930 * @fh_type: type of file handle
931 * @get_inode: filesystem callback to retrieve inode
932 *
933 * This function decodes @fid as long as it has one of the well-known
934 * Linux filehandle types and calls @get_inode on it to retrieve the
935 * inode for the _parent_ object specified in the file handle if it
936 * is specified in the file handle, or NULL otherwise.
937 */
938struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
939 int fh_len, int fh_type, struct inode *(*get_inode)
940 (struct super_block *sb, u64 ino, u32 gen))
941{
942 struct inode *inode = NULL;
943
944 if (fh_len <= 2)
945 return NULL;
946
947 switch (fh_type) {
948 case FILEID_INO32_GEN_PARENT:
949 inode = get_inode(sb, fid->i32.parent_ino,
950 (fh_len > 3 ? fid->i32.parent_gen : 0));
951 break;
952 }
953
954 return d_obtain_alias(inode);
955}
956EXPORT_SYMBOL_GPL(generic_fh_to_parent);
957
958/**
959 * __generic_file_fsync - generic fsync implementation for simple filesystems
960 *
961 * @file: file to synchronize
962 * @start: start offset in bytes
963 * @end: end offset in bytes (inclusive)
964 * @datasync: only synchronize essential metadata if true
965 *
966 * This is a generic implementation of the fsync method for simple
967 * filesystems which track all non-inode metadata in the buffers list
968 * hanging off the address_space structure.
969 */
970int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
971 int datasync)
972{
973 struct inode *inode = file->f_mapping->host;
974 int err;
975 int ret;
976
977 err = file_write_and_wait_range(file, start, end);
978 if (err)
979 return err;
980
981 inode_lock(inode);
982 ret = sync_mapping_buffers(inode->i_mapping);
983 if (!(inode->i_state & I_DIRTY_ALL))
984 goto out;
985 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
986 goto out;
987
988 err = sync_inode_metadata(inode, 1);
989 if (ret == 0)
990 ret = err;
991
992out:
993 inode_unlock(inode);
994 /* check and advance again to catch errors after syncing out buffers */
995 err = file_check_and_advance_wb_err(file);
996 if (ret == 0)
997 ret = err;
998 return ret;
999}
1000EXPORT_SYMBOL(__generic_file_fsync);
1001
1002/**
1003 * generic_file_fsync - generic fsync implementation for simple filesystems
1004 * with flush
1005 * @file: file to synchronize
1006 * @start: start offset in bytes
1007 * @end: end offset in bytes (inclusive)
1008 * @datasync: only synchronize essential metadata if true
1009 *
1010 */
1011
1012int generic_file_fsync(struct file *file, loff_t start, loff_t end,
1013 int datasync)
1014{
1015 struct inode *inode = file->f_mapping->host;
1016 int err;
1017
1018 err = __generic_file_fsync(file, start, end, datasync);
1019 if (err)
1020 return err;
1021 return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
1022}
1023EXPORT_SYMBOL(generic_file_fsync);
1024
1025/**
1026 * generic_check_addressable - Check addressability of file system
1027 * @blocksize_bits: log of file system block size
1028 * @num_blocks: number of blocks in file system
1029 *
1030 * Determine whether a file system with @num_blocks blocks (and a
1031 * block size of 2**@blocksize_bits) is addressable by the sector_t
1032 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
1033 */
1034int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
1035{
1036 u64 last_fs_block = num_blocks - 1;
1037 u64 last_fs_page =
1038 last_fs_block >> (PAGE_SHIFT - blocksize_bits);
1039
1040 if (unlikely(num_blocks == 0))
1041 return 0;
1042
1043 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
1044 return -EINVAL;
1045
1046 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
1047 (last_fs_page > (pgoff_t)(~0ULL))) {
1048 return -EFBIG;
1049 }
1050 return 0;
1051}
1052EXPORT_SYMBOL(generic_check_addressable);
1053
1054/*
1055 * No-op implementation of ->fsync for in-memory filesystems.
1056 */
1057int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1058{
1059 return 0;
1060}
1061EXPORT_SYMBOL(noop_fsync);
1062
1063int noop_set_page_dirty(struct page *page)
1064{
1065 /*
1066 * Unlike __set_page_dirty_no_writeback that handles dirty page
1067 * tracking in the page object, dax does all dirty tracking in
1068 * the inode address_space in response to mkwrite faults. In the
1069 * dax case we only need to worry about potentially dirty CPU
1070 * caches, not dirty page cache pages to write back.
1071 *
1072 * This callback is defined to prevent fallback to
1073 * __set_page_dirty_buffers() in set_page_dirty().
1074 */
1075 return 0;
1076}
1077EXPORT_SYMBOL_GPL(noop_set_page_dirty);
1078
1079void noop_invalidatepage(struct page *page, unsigned int offset,
1080 unsigned int length)
1081{
1082 /*
1083 * There is no page cache to invalidate in the dax case, however
1084 * we need this callback defined to prevent falling back to
1085 * block_invalidatepage() in do_invalidatepage().
1086 */
1087}
1088EXPORT_SYMBOL_GPL(noop_invalidatepage);
1089
1090ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
1091{
1092 /*
1093 * iomap based filesystems support direct I/O without need for
1094 * this callback. However, it still needs to be set in
1095 * inode->a_ops so that open/fcntl know that direct I/O is
1096 * generally supported.
1097 */
1098 return -EINVAL;
1099}
1100EXPORT_SYMBOL_GPL(noop_direct_IO);
1101
1102/* Because kfree isn't assignment-compatible with void(void*) ;-/ */
1103void kfree_link(void *p)
1104{
1105 kfree(p);
1106}
1107EXPORT_SYMBOL(kfree_link);
1108
1109/*
1110 * nop .set_page_dirty method so that people can use .page_mkwrite on
1111 * anon inodes.
1112 */
1113static int anon_set_page_dirty(struct page *page)
1114{
1115 return 0;
1116};
1117
1118/*
1119 * A single inode exists for all anon_inode files. Contrary to pipes,
1120 * anon_inode inodes have no associated per-instance data, so we need
1121 * only allocate one of them.
1122 */
1123struct inode *alloc_anon_inode(struct super_block *s)
1124{
1125 static const struct address_space_operations anon_aops = {
1126 .set_page_dirty = anon_set_page_dirty,
1127 };
1128 struct inode *inode = new_inode_pseudo(s);
1129
1130 if (!inode)
1131 return ERR_PTR(-ENOMEM);
1132
1133 inode->i_ino = get_next_ino();
1134 inode->i_mapping->a_ops = &anon_aops;
1135
1136 /*
1137 * Mark the inode dirty from the very beginning,
1138 * that way it will never be moved to the dirty
1139 * list because mark_inode_dirty() will think
1140 * that it already _is_ on the dirty list.
1141 */
1142 inode->i_state = I_DIRTY;
1143 inode->i_mode = S_IRUSR | S_IWUSR;
1144 inode->i_uid = current_fsuid();
1145 inode->i_gid = current_fsgid();
1146 inode->i_flags |= S_PRIVATE;
1147 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
1148 return inode;
1149}
1150EXPORT_SYMBOL(alloc_anon_inode);
1151
1152/**
1153 * simple_nosetlease - generic helper for prohibiting leases
1154 * @filp: file pointer
1155 * @arg: type of lease to obtain
1156 * @flp: new lease supplied for insertion
1157 * @priv: private data for lm_setup operation
1158 *
1159 * Generic helper for filesystems that do not wish to allow leases to be set.
1160 * All arguments are ignored and it just returns -EINVAL.
1161 */
1162int
1163simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
1164 void **priv)
1165{
1166 return -EINVAL;
1167}
1168EXPORT_SYMBOL(simple_nosetlease);
1169
1170const char *simple_get_link(struct dentry *dentry, struct inode *inode,
1171 struct delayed_call *done)
1172{
1173 return inode->i_link;
1174}
1175EXPORT_SYMBOL(simple_get_link);
1176
1177const struct inode_operations simple_symlink_inode_operations = {
1178 .get_link = simple_get_link,
1179};
1180EXPORT_SYMBOL(simple_symlink_inode_operations);
1181
1182/*
1183 * Operations for a permanently empty directory.
1184 */
1185static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
1186{
1187 return ERR_PTR(-ENOENT);
1188}
1189
1190static int empty_dir_getattr(const struct path *path, struct kstat *stat,
1191 u32 request_mask, unsigned int query_flags)
1192{
1193 struct inode *inode = d_inode(path->dentry);
1194 generic_fillattr(inode, stat);
1195 return 0;
1196}
1197
1198static int empty_dir_setattr(struct dentry *dentry, struct iattr *attr)
1199{
1200 return -EPERM;
1201}
1202
1203static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
1204{
1205 return -EOPNOTSUPP;
1206}
1207
1208static const struct inode_operations empty_dir_inode_operations = {
1209 .lookup = empty_dir_lookup,
1210 .permission = generic_permission,
1211 .setattr = empty_dir_setattr,
1212 .getattr = empty_dir_getattr,
1213 .listxattr = empty_dir_listxattr,
1214};
1215
1216static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
1217{
1218 /* An empty directory has two entries . and .. at offsets 0 and 1 */
1219 return generic_file_llseek_size(file, offset, whence, 2, 2);
1220}
1221
1222static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
1223{
1224 dir_emit_dots(file, ctx);
1225 return 0;
1226}
1227
1228static const struct file_operations empty_dir_operations = {
1229 .llseek = empty_dir_llseek,
1230 .read = generic_read_dir,
1231 .iterate_shared = empty_dir_readdir,
1232 .fsync = noop_fsync,
1233};
1234
1235
1236void make_empty_dir_inode(struct inode *inode)
1237{
1238 set_nlink(inode, 2);
1239 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
1240 inode->i_uid = GLOBAL_ROOT_UID;
1241 inode->i_gid = GLOBAL_ROOT_GID;
1242 inode->i_rdev = 0;
1243 inode->i_size = 0;
1244 inode->i_blkbits = PAGE_SHIFT;
1245 inode->i_blocks = 0;
1246
1247 inode->i_op = &empty_dir_inode_operations;
1248 inode->i_opflags &= ~IOP_XATTR;
1249 inode->i_fop = &empty_dir_operations;
1250}
1251
1252bool is_empty_dir_inode(struct inode *inode)
1253{
1254 return (inode->i_fop == &empty_dir_operations) &&
1255 (inode->i_op == &empty_dir_inode_operations);
1256}