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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/mount.h>
11#include <linux/vfs.h>
12#include <linux/quotaops.h>
13#include <linux/mutex.h>
14#include <linux/namei.h>
15#include <linux/exportfs.h>
16#include <linux/writeback.h>
17#include <linux/buffer_head.h> /* sync_mapping_buffers */
18
19#include <asm/uaccess.h>
20
21#include "internal.h"
22
23int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
24 struct kstat *stat)
25{
26 struct inode *inode = d_inode(dentry);
27 generic_fillattr(inode, stat);
28 stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
29 return 0;
30}
31EXPORT_SYMBOL(simple_getattr);
32
33int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
34{
35 buf->f_type = dentry->d_sb->s_magic;
36 buf->f_bsize = PAGE_SIZE;
37 buf->f_namelen = NAME_MAX;
38 return 0;
39}
40EXPORT_SYMBOL(simple_statfs);
41
42/*
43 * Retaining negative dentries for an in-memory filesystem just wastes
44 * memory and lookup time: arrange for them to be deleted immediately.
45 */
46int always_delete_dentry(const struct dentry *dentry)
47{
48 return 1;
49}
50EXPORT_SYMBOL(always_delete_dentry);
51
52const struct dentry_operations simple_dentry_operations = {
53 .d_delete = always_delete_dentry,
54};
55EXPORT_SYMBOL(simple_dentry_operations);
56
57/*
58 * Lookup the data. This is trivial - if the dentry didn't already
59 * exist, we know it is negative. Set d_op to delete negative dentries.
60 */
61struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
62{
63 if (dentry->d_name.len > NAME_MAX)
64 return ERR_PTR(-ENAMETOOLONG);
65 if (!dentry->d_sb->s_d_op)
66 d_set_d_op(dentry, &simple_dentry_operations);
67 d_add(dentry, NULL);
68 return NULL;
69}
70EXPORT_SYMBOL(simple_lookup);
71
72int dcache_dir_open(struct inode *inode, struct file *file)
73{
74 static struct qstr cursor_name = QSTR_INIT(".", 1);
75
76 file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
77
78 return file->private_data ? 0 : -ENOMEM;
79}
80EXPORT_SYMBOL(dcache_dir_open);
81
82int dcache_dir_close(struct inode *inode, struct file *file)
83{
84 dput(file->private_data);
85 return 0;
86}
87EXPORT_SYMBOL(dcache_dir_close);
88
89loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
90{
91 struct dentry *dentry = file->f_path.dentry;
92 inode_lock(d_inode(dentry));
93 switch (whence) {
94 case 1:
95 offset += file->f_pos;
96 case 0:
97 if (offset >= 0)
98 break;
99 default:
100 inode_unlock(d_inode(dentry));
101 return -EINVAL;
102 }
103 if (offset != file->f_pos) {
104 file->f_pos = offset;
105 if (file->f_pos >= 2) {
106 struct list_head *p;
107 struct dentry *cursor = file->private_data;
108 loff_t n = file->f_pos - 2;
109
110 spin_lock(&dentry->d_lock);
111 /* d_lock not required for cursor */
112 list_del(&cursor->d_child);
113 p = dentry->d_subdirs.next;
114 while (n && p != &dentry->d_subdirs) {
115 struct dentry *next;
116 next = list_entry(p, struct dentry, d_child);
117 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
118 if (simple_positive(next))
119 n--;
120 spin_unlock(&next->d_lock);
121 p = p->next;
122 }
123 list_add_tail(&cursor->d_child, p);
124 spin_unlock(&dentry->d_lock);
125 }
126 }
127 inode_unlock(d_inode(dentry));
128 return offset;
129}
130EXPORT_SYMBOL(dcache_dir_lseek);
131
132/* Relationship between i_mode and the DT_xxx types */
133static inline unsigned char dt_type(struct inode *inode)
134{
135 return (inode->i_mode >> 12) & 15;
136}
137
138/*
139 * Directory is locked and all positive dentries in it are safe, since
140 * for ramfs-type trees they can't go away without unlink() or rmdir(),
141 * both impossible due to the lock on directory.
142 */
143
144int dcache_readdir(struct file *file, struct dir_context *ctx)
145{
146 struct dentry *dentry = file->f_path.dentry;
147 struct dentry *cursor = file->private_data;
148 struct list_head *p, *q = &cursor->d_child;
149
150 if (!dir_emit_dots(file, ctx))
151 return 0;
152 spin_lock(&dentry->d_lock);
153 if (ctx->pos == 2)
154 list_move(q, &dentry->d_subdirs);
155
156 for (p = q->next; p != &dentry->d_subdirs; p = p->next) {
157 struct dentry *next = list_entry(p, struct dentry, d_child);
158 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
159 if (!simple_positive(next)) {
160 spin_unlock(&next->d_lock);
161 continue;
162 }
163
164 spin_unlock(&next->d_lock);
165 spin_unlock(&dentry->d_lock);
166 if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
167 d_inode(next)->i_ino, dt_type(d_inode(next))))
168 return 0;
169 spin_lock(&dentry->d_lock);
170 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
171 /* next is still alive */
172 list_move(q, p);
173 spin_unlock(&next->d_lock);
174 p = q;
175 ctx->pos++;
176 }
177 spin_unlock(&dentry->d_lock);
178 return 0;
179}
180EXPORT_SYMBOL(dcache_readdir);
181
182ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
183{
184 return -EISDIR;
185}
186EXPORT_SYMBOL(generic_read_dir);
187
188const struct file_operations simple_dir_operations = {
189 .open = dcache_dir_open,
190 .release = dcache_dir_close,
191 .llseek = dcache_dir_lseek,
192 .read = generic_read_dir,
193 .iterate = dcache_readdir,
194 .fsync = noop_fsync,
195};
196EXPORT_SYMBOL(simple_dir_operations);
197
198const struct inode_operations simple_dir_inode_operations = {
199 .lookup = simple_lookup,
200};
201EXPORT_SYMBOL(simple_dir_inode_operations);
202
203static const struct super_operations simple_super_operations = {
204 .statfs = simple_statfs,
205};
206
207/*
208 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
209 * will never be mountable)
210 */
211struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name,
212 const struct super_operations *ops,
213 const struct dentry_operations *dops, unsigned long magic)
214{
215 struct super_block *s;
216 struct dentry *dentry;
217 struct inode *root;
218 struct qstr d_name = QSTR_INIT(name, strlen(name));
219
220 s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL);
221 if (IS_ERR(s))
222 return ERR_CAST(s);
223
224 s->s_maxbytes = MAX_LFS_FILESIZE;
225 s->s_blocksize = PAGE_SIZE;
226 s->s_blocksize_bits = PAGE_SHIFT;
227 s->s_magic = magic;
228 s->s_op = ops ? ops : &simple_super_operations;
229 s->s_time_gran = 1;
230 root = new_inode(s);
231 if (!root)
232 goto Enomem;
233 /*
234 * since this is the first inode, make it number 1. New inodes created
235 * after this must take care not to collide with it (by passing
236 * max_reserved of 1 to iunique).
237 */
238 root->i_ino = 1;
239 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
240 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
241 dentry = __d_alloc(s, &d_name);
242 if (!dentry) {
243 iput(root);
244 goto Enomem;
245 }
246 d_instantiate(dentry, root);
247 s->s_root = dentry;
248 s->s_d_op = dops;
249 s->s_flags |= MS_ACTIVE;
250 return dget(s->s_root);
251
252Enomem:
253 deactivate_locked_super(s);
254 return ERR_PTR(-ENOMEM);
255}
256EXPORT_SYMBOL(mount_pseudo);
257
258int simple_open(struct inode *inode, struct file *file)
259{
260 if (inode->i_private)
261 file->private_data = inode->i_private;
262 return 0;
263}
264EXPORT_SYMBOL(simple_open);
265
266int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
267{
268 struct inode *inode = d_inode(old_dentry);
269
270 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
271 inc_nlink(inode);
272 ihold(inode);
273 dget(dentry);
274 d_instantiate(dentry, inode);
275 return 0;
276}
277EXPORT_SYMBOL(simple_link);
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_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}
298EXPORT_SYMBOL(simple_empty);
299
300int simple_unlink(struct inode *dir, struct dentry *dentry)
301{
302 struct inode *inode = d_inode(dentry);
303
304 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
305 drop_nlink(inode);
306 dput(dentry);
307 return 0;
308}
309EXPORT_SYMBOL(simple_unlink);
310
311int simple_rmdir(struct inode *dir, struct dentry *dentry)
312{
313 if (!simple_empty(dentry))
314 return -ENOTEMPTY;
315
316 drop_nlink(d_inode(dentry));
317 simple_unlink(dir, dentry);
318 drop_nlink(dir);
319 return 0;
320}
321EXPORT_SYMBOL(simple_rmdir);
322
323int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
324 struct inode *new_dir, struct dentry *new_dentry)
325{
326 struct inode *inode = d_inode(old_dentry);
327 int they_are_dirs = d_is_dir(old_dentry);
328
329 if (!simple_empty(new_dentry))
330 return -ENOTEMPTY;
331
332 if (d_really_is_positive(new_dentry)) {
333 simple_unlink(new_dir, new_dentry);
334 if (they_are_dirs) {
335 drop_nlink(d_inode(new_dentry));
336 drop_nlink(old_dir);
337 }
338 } else if (they_are_dirs) {
339 drop_nlink(old_dir);
340 inc_nlink(new_dir);
341 }
342
343 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
344 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
345
346 return 0;
347}
348EXPORT_SYMBOL(simple_rename);
349
350/**
351 * simple_setattr - setattr for simple filesystem
352 * @dentry: dentry
353 * @iattr: iattr structure
354 *
355 * Returns 0 on success, -error on failure.
356 *
357 * simple_setattr is a simple ->setattr implementation without a proper
358 * implementation of size changes.
359 *
360 * It can either be used for in-memory filesystems or special files
361 * on simple regular filesystems. Anything that needs to change on-disk
362 * or wire state on size changes needs its own setattr method.
363 */
364int simple_setattr(struct dentry *dentry, struct iattr *iattr)
365{
366 struct inode *inode = d_inode(dentry);
367 int error;
368
369 error = inode_change_ok(inode, iattr);
370 if (error)
371 return error;
372
373 if (iattr->ia_valid & ATTR_SIZE)
374 truncate_setsize(inode, iattr->ia_size);
375 setattr_copy(inode, iattr);
376 mark_inode_dirty(inode);
377 return 0;
378}
379EXPORT_SYMBOL(simple_setattr);
380
381int simple_readpage(struct file *file, struct page *page)
382{
383 clear_highpage(page);
384 flush_dcache_page(page);
385 SetPageUptodate(page);
386 unlock_page(page);
387 return 0;
388}
389EXPORT_SYMBOL(simple_readpage);
390
391int simple_write_begin(struct file *file, struct address_space *mapping,
392 loff_t pos, unsigned len, unsigned flags,
393 struct page **pagep, void **fsdata)
394{
395 struct page *page;
396 pgoff_t index;
397
398 index = pos >> PAGE_SHIFT;
399
400 page = grab_cache_page_write_begin(mapping, index, flags);
401 if (!page)
402 return -ENOMEM;
403
404 *pagep = page;
405
406 if (!PageUptodate(page) && (len != PAGE_SIZE)) {
407 unsigned from = pos & (PAGE_SIZE - 1);
408
409 zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
410 }
411 return 0;
412}
413EXPORT_SYMBOL(simple_write_begin);
414
415/**
416 * simple_write_end - .write_end helper for non-block-device FSes
417 * @available: See .write_end of address_space_operations
418 * @file: "
419 * @mapping: "
420 * @pos: "
421 * @len: "
422 * @copied: "
423 * @page: "
424 * @fsdata: "
425 *
426 * simple_write_end does the minimum needed for updating a page after writing is
427 * done. It has the same API signature as the .write_end of
428 * address_space_operations vector. So it can just be set onto .write_end for
429 * FSes that don't need any other processing. i_mutex is assumed to be held.
430 * Block based filesystems should use generic_write_end().
431 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
432 * is not called, so a filesystem that actually does store data in .write_inode
433 * should extend on what's done here with a call to mark_inode_dirty() in the
434 * case that i_size has changed.
435 */
436int simple_write_end(struct file *file, struct address_space *mapping,
437 loff_t pos, unsigned len, unsigned copied,
438 struct page *page, void *fsdata)
439{
440 struct inode *inode = page->mapping->host;
441 loff_t last_pos = pos + copied;
442
443 /* zero the stale part of the page if we did a short copy */
444 if (copied < len) {
445 unsigned from = pos & (PAGE_SIZE - 1);
446
447 zero_user(page, from + copied, len - copied);
448 }
449
450 if (!PageUptodate(page))
451 SetPageUptodate(page);
452 /*
453 * No need to use i_size_read() here, the i_size
454 * cannot change under us because we hold the i_mutex.
455 */
456 if (last_pos > inode->i_size)
457 i_size_write(inode, last_pos);
458
459 set_page_dirty(page);
460 unlock_page(page);
461 put_page(page);
462
463 return copied;
464}
465EXPORT_SYMBOL(simple_write_end);
466
467/*
468 * the inodes created here are not hashed. If you use iunique to generate
469 * unique inode values later for this filesystem, then you must take care
470 * to pass it an appropriate max_reserved value to avoid collisions.
471 */
472int simple_fill_super(struct super_block *s, unsigned long magic,
473 struct tree_descr *files)
474{
475 struct inode *inode;
476 struct dentry *root;
477 struct dentry *dentry;
478 int i;
479
480 s->s_blocksize = PAGE_SIZE;
481 s->s_blocksize_bits = PAGE_SHIFT;
482 s->s_magic = magic;
483 s->s_op = &simple_super_operations;
484 s->s_time_gran = 1;
485
486 inode = new_inode(s);
487 if (!inode)
488 return -ENOMEM;
489 /*
490 * because the root inode is 1, the files array must not contain an
491 * entry at index 1
492 */
493 inode->i_ino = 1;
494 inode->i_mode = S_IFDIR | 0755;
495 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
496 inode->i_op = &simple_dir_inode_operations;
497 inode->i_fop = &simple_dir_operations;
498 set_nlink(inode, 2);
499 root = d_make_root(inode);
500 if (!root)
501 return -ENOMEM;
502 for (i = 0; !files->name || files->name[0]; i++, files++) {
503 if (!files->name)
504 continue;
505
506 /* warn if it tries to conflict with the root inode */
507 if (unlikely(i == 1))
508 printk(KERN_WARNING "%s: %s passed in a files array"
509 "with an index of 1!\n", __func__,
510 s->s_type->name);
511
512 dentry = d_alloc_name(root, files->name);
513 if (!dentry)
514 goto out;
515 inode = new_inode(s);
516 if (!inode) {
517 dput(dentry);
518 goto out;
519 }
520 inode->i_mode = S_IFREG | files->mode;
521 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
522 inode->i_fop = files->ops;
523 inode->i_ino = i;
524 d_add(dentry, inode);
525 }
526 s->s_root = root;
527 return 0;
528out:
529 d_genocide(root);
530 shrink_dcache_parent(root);
531 dput(root);
532 return -ENOMEM;
533}
534EXPORT_SYMBOL(simple_fill_super);
535
536static DEFINE_SPINLOCK(pin_fs_lock);
537
538int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
539{
540 struct vfsmount *mnt = NULL;
541 spin_lock(&pin_fs_lock);
542 if (unlikely(!*mount)) {
543 spin_unlock(&pin_fs_lock);
544 mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, NULL);
545 if (IS_ERR(mnt))
546 return PTR_ERR(mnt);
547 spin_lock(&pin_fs_lock);
548 if (!*mount)
549 *mount = mnt;
550 }
551 mntget(*mount);
552 ++*count;
553 spin_unlock(&pin_fs_lock);
554 mntput(mnt);
555 return 0;
556}
557EXPORT_SYMBOL(simple_pin_fs);
558
559void simple_release_fs(struct vfsmount **mount, int *count)
560{
561 struct vfsmount *mnt;
562 spin_lock(&pin_fs_lock);
563 mnt = *mount;
564 if (!--*count)
565 *mount = NULL;
566 spin_unlock(&pin_fs_lock);
567 mntput(mnt);
568}
569EXPORT_SYMBOL(simple_release_fs);
570
571/**
572 * simple_read_from_buffer - copy data from the buffer to user space
573 * @to: the user space buffer to read to
574 * @count: the maximum number of bytes to read
575 * @ppos: the current position in the buffer
576 * @from: the buffer to read from
577 * @available: the size of the buffer
578 *
579 * The simple_read_from_buffer() function reads up to @count bytes from the
580 * buffer @from at offset @ppos into the user space address starting at @to.
581 *
582 * On success, the number of bytes read is returned and the offset @ppos is
583 * advanced by this number, or negative value is returned on error.
584 **/
585ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
586 const void *from, size_t available)
587{
588 loff_t pos = *ppos;
589 size_t ret;
590
591 if (pos < 0)
592 return -EINVAL;
593 if (pos >= available || !count)
594 return 0;
595 if (count > available - pos)
596 count = available - pos;
597 ret = copy_to_user(to, from + pos, count);
598 if (ret == count)
599 return -EFAULT;
600 count -= ret;
601 *ppos = pos + count;
602 return count;
603}
604EXPORT_SYMBOL(simple_read_from_buffer);
605
606/**
607 * simple_write_to_buffer - copy data from user space to the buffer
608 * @to: the buffer to write to
609 * @available: the size of the buffer
610 * @ppos: the current position in the buffer
611 * @from: the user space buffer to read from
612 * @count: the maximum number of bytes to read
613 *
614 * The simple_write_to_buffer() function reads up to @count bytes from the user
615 * space address starting at @from into the buffer @to at offset @ppos.
616 *
617 * On success, the number of bytes written is returned and the offset @ppos is
618 * advanced by this number, or negative value is returned on error.
619 **/
620ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
621 const void __user *from, size_t count)
622{
623 loff_t pos = *ppos;
624 size_t res;
625
626 if (pos < 0)
627 return -EINVAL;
628 if (pos >= available || !count)
629 return 0;
630 if (count > available - pos)
631 count = available - pos;
632 res = copy_from_user(to + pos, from, count);
633 if (res == count)
634 return -EFAULT;
635 count -= res;
636 *ppos = pos + count;
637 return count;
638}
639EXPORT_SYMBOL(simple_write_to_buffer);
640
641/**
642 * memory_read_from_buffer - copy data from the buffer
643 * @to: the kernel space buffer to read to
644 * @count: the maximum number of bytes to read
645 * @ppos: the current position in the buffer
646 * @from: the buffer to read from
647 * @available: the size of the buffer
648 *
649 * The memory_read_from_buffer() function reads up to @count bytes from the
650 * buffer @from at offset @ppos into the kernel space address starting at @to.
651 *
652 * On success, the number of bytes read is returned and the offset @ppos is
653 * advanced by this number, or negative value is returned on error.
654 **/
655ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
656 const void *from, size_t available)
657{
658 loff_t pos = *ppos;
659
660 if (pos < 0)
661 return -EINVAL;
662 if (pos >= available)
663 return 0;
664 if (count > available - pos)
665 count = available - pos;
666 memcpy(to, from + pos, count);
667 *ppos = pos + count;
668
669 return count;
670}
671EXPORT_SYMBOL(memory_read_from_buffer);
672
673/*
674 * Transaction based IO.
675 * The file expects a single write which triggers the transaction, and then
676 * possibly a read which collects the result - which is stored in a
677 * file-local buffer.
678 */
679
680void simple_transaction_set(struct file *file, size_t n)
681{
682 struct simple_transaction_argresp *ar = file->private_data;
683
684 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
685
686 /*
687 * The barrier ensures that ar->size will really remain zero until
688 * ar->data is ready for reading.
689 */
690 smp_mb();
691 ar->size = n;
692}
693EXPORT_SYMBOL(simple_transaction_set);
694
695char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
696{
697 struct simple_transaction_argresp *ar;
698 static DEFINE_SPINLOCK(simple_transaction_lock);
699
700 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
701 return ERR_PTR(-EFBIG);
702
703 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
704 if (!ar)
705 return ERR_PTR(-ENOMEM);
706
707 spin_lock(&simple_transaction_lock);
708
709 /* only one write allowed per open */
710 if (file->private_data) {
711 spin_unlock(&simple_transaction_lock);
712 free_page((unsigned long)ar);
713 return ERR_PTR(-EBUSY);
714 }
715
716 file->private_data = ar;
717
718 spin_unlock(&simple_transaction_lock);
719
720 if (copy_from_user(ar->data, buf, size))
721 return ERR_PTR(-EFAULT);
722
723 return ar->data;
724}
725EXPORT_SYMBOL(simple_transaction_get);
726
727ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
728{
729 struct simple_transaction_argresp *ar = file->private_data;
730
731 if (!ar)
732 return 0;
733 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
734}
735EXPORT_SYMBOL(simple_transaction_read);
736
737int simple_transaction_release(struct inode *inode, struct file *file)
738{
739 free_page((unsigned long)file->private_data);
740 return 0;
741}
742EXPORT_SYMBOL(simple_transaction_release);
743
744/* Simple attribute files */
745
746struct simple_attr {
747 int (*get)(void *, u64 *);
748 int (*set)(void *, u64);
749 char get_buf[24]; /* enough to store a u64 and "\n\0" */
750 char set_buf[24];
751 void *data;
752 const char *fmt; /* format for read operation */
753 struct mutex mutex; /* protects access to these buffers */
754};
755
756/* simple_attr_open is called by an actual attribute open file operation
757 * to set the attribute specific access operations. */
758int simple_attr_open(struct inode *inode, struct file *file,
759 int (*get)(void *, u64 *), int (*set)(void *, u64),
760 const char *fmt)
761{
762 struct simple_attr *attr;
763
764 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
765 if (!attr)
766 return -ENOMEM;
767
768 attr->get = get;
769 attr->set = set;
770 attr->data = inode->i_private;
771 attr->fmt = fmt;
772 mutex_init(&attr->mutex);
773
774 file->private_data = attr;
775
776 return nonseekable_open(inode, file);
777}
778EXPORT_SYMBOL_GPL(simple_attr_open);
779
780int simple_attr_release(struct inode *inode, struct file *file)
781{
782 kfree(file->private_data);
783 return 0;
784}
785EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
786
787/* read from the buffer that is filled with the get function */
788ssize_t simple_attr_read(struct file *file, char __user *buf,
789 size_t len, loff_t *ppos)
790{
791 struct simple_attr *attr;
792 size_t size;
793 ssize_t ret;
794
795 attr = file->private_data;
796
797 if (!attr->get)
798 return -EACCES;
799
800 ret = mutex_lock_interruptible(&attr->mutex);
801 if (ret)
802 return ret;
803
804 if (*ppos) { /* continued read */
805 size = strlen(attr->get_buf);
806 } else { /* first read */
807 u64 val;
808 ret = attr->get(attr->data, &val);
809 if (ret)
810 goto out;
811
812 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
813 attr->fmt, (unsigned long long)val);
814 }
815
816 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
817out:
818 mutex_unlock(&attr->mutex);
819 return ret;
820}
821EXPORT_SYMBOL_GPL(simple_attr_read);
822
823/* interpret the buffer as a number to call the set function with */
824ssize_t simple_attr_write(struct file *file, const char __user *buf,
825 size_t len, loff_t *ppos)
826{
827 struct simple_attr *attr;
828 u64 val;
829 size_t size;
830 ssize_t ret;
831
832 attr = file->private_data;
833 if (!attr->set)
834 return -EACCES;
835
836 ret = mutex_lock_interruptible(&attr->mutex);
837 if (ret)
838 return ret;
839
840 ret = -EFAULT;
841 size = min(sizeof(attr->set_buf) - 1, len);
842 if (copy_from_user(attr->set_buf, buf, size))
843 goto out;
844
845 attr->set_buf[size] = '\0';
846 val = simple_strtoll(attr->set_buf, NULL, 0);
847 ret = attr->set(attr->data, val);
848 if (ret == 0)
849 ret = len; /* on success, claim we got the whole input */
850out:
851 mutex_unlock(&attr->mutex);
852 return ret;
853}
854EXPORT_SYMBOL_GPL(simple_attr_write);
855
856/**
857 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
858 * @sb: filesystem to do the file handle conversion on
859 * @fid: file handle to convert
860 * @fh_len: length of the file handle in bytes
861 * @fh_type: type of file handle
862 * @get_inode: filesystem callback to retrieve inode
863 *
864 * This function decodes @fid as long as it has one of the well-known
865 * Linux filehandle types and calls @get_inode on it to retrieve the
866 * inode for the object specified in the file handle.
867 */
868struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
869 int fh_len, int fh_type, struct inode *(*get_inode)
870 (struct super_block *sb, u64 ino, u32 gen))
871{
872 struct inode *inode = NULL;
873
874 if (fh_len < 2)
875 return NULL;
876
877 switch (fh_type) {
878 case FILEID_INO32_GEN:
879 case FILEID_INO32_GEN_PARENT:
880 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
881 break;
882 }
883
884 return d_obtain_alias(inode);
885}
886EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
887
888/**
889 * generic_fh_to_parent - generic helper for the fh_to_parent export operation
890 * @sb: filesystem to do the file handle conversion on
891 * @fid: file handle to convert
892 * @fh_len: length of the file handle in bytes
893 * @fh_type: type of file handle
894 * @get_inode: filesystem callback to retrieve inode
895 *
896 * This function decodes @fid as long as it has one of the well-known
897 * Linux filehandle types and calls @get_inode on it to retrieve the
898 * inode for the _parent_ object specified in the file handle if it
899 * is specified in the file handle, or NULL otherwise.
900 */
901struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
902 int fh_len, int fh_type, struct inode *(*get_inode)
903 (struct super_block *sb, u64 ino, u32 gen))
904{
905 struct inode *inode = NULL;
906
907 if (fh_len <= 2)
908 return NULL;
909
910 switch (fh_type) {
911 case FILEID_INO32_GEN_PARENT:
912 inode = get_inode(sb, fid->i32.parent_ino,
913 (fh_len > 3 ? fid->i32.parent_gen : 0));
914 break;
915 }
916
917 return d_obtain_alias(inode);
918}
919EXPORT_SYMBOL_GPL(generic_fh_to_parent);
920
921/**
922 * __generic_file_fsync - generic fsync implementation for simple filesystems
923 *
924 * @file: file to synchronize
925 * @start: start offset in bytes
926 * @end: end offset in bytes (inclusive)
927 * @datasync: only synchronize essential metadata if true
928 *
929 * This is a generic implementation of the fsync method for simple
930 * filesystems which track all non-inode metadata in the buffers list
931 * hanging off the address_space structure.
932 */
933int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
934 int datasync)
935{
936 struct inode *inode = file->f_mapping->host;
937 int err;
938 int ret;
939
940 err = filemap_write_and_wait_range(inode->i_mapping, start, end);
941 if (err)
942 return err;
943
944 inode_lock(inode);
945 ret = sync_mapping_buffers(inode->i_mapping);
946 if (!(inode->i_state & I_DIRTY_ALL))
947 goto out;
948 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
949 goto out;
950
951 err = sync_inode_metadata(inode, 1);
952 if (ret == 0)
953 ret = err;
954
955out:
956 inode_unlock(inode);
957 return ret;
958}
959EXPORT_SYMBOL(__generic_file_fsync);
960
961/**
962 * generic_file_fsync - generic fsync implementation for simple filesystems
963 * with flush
964 * @file: file to synchronize
965 * @start: start offset in bytes
966 * @end: end offset in bytes (inclusive)
967 * @datasync: only synchronize essential metadata if true
968 *
969 */
970
971int generic_file_fsync(struct file *file, loff_t start, loff_t end,
972 int datasync)
973{
974 struct inode *inode = file->f_mapping->host;
975 int err;
976
977 err = __generic_file_fsync(file, start, end, datasync);
978 if (err)
979 return err;
980 return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
981}
982EXPORT_SYMBOL(generic_file_fsync);
983
984/**
985 * generic_check_addressable - Check addressability of file system
986 * @blocksize_bits: log of file system block size
987 * @num_blocks: number of blocks in file system
988 *
989 * Determine whether a file system with @num_blocks blocks (and a
990 * block size of 2**@blocksize_bits) is addressable by the sector_t
991 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
992 */
993int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
994{
995 u64 last_fs_block = num_blocks - 1;
996 u64 last_fs_page =
997 last_fs_block >> (PAGE_SHIFT - blocksize_bits);
998
999 if (unlikely(num_blocks == 0))
1000 return 0;
1001
1002 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
1003 return -EINVAL;
1004
1005 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
1006 (last_fs_page > (pgoff_t)(~0ULL))) {
1007 return -EFBIG;
1008 }
1009 return 0;
1010}
1011EXPORT_SYMBOL(generic_check_addressable);
1012
1013/*
1014 * No-op implementation of ->fsync for in-memory filesystems.
1015 */
1016int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1017{
1018 return 0;
1019}
1020EXPORT_SYMBOL(noop_fsync);
1021
1022/* Because kfree isn't assignment-compatible with void(void*) ;-/ */
1023void kfree_link(void *p)
1024{
1025 kfree(p);
1026}
1027EXPORT_SYMBOL(kfree_link);
1028
1029/*
1030 * nop .set_page_dirty method so that people can use .page_mkwrite on
1031 * anon inodes.
1032 */
1033static int anon_set_page_dirty(struct page *page)
1034{
1035 return 0;
1036};
1037
1038/*
1039 * A single inode exists for all anon_inode files. Contrary to pipes,
1040 * anon_inode inodes have no associated per-instance data, so we need
1041 * only allocate one of them.
1042 */
1043struct inode *alloc_anon_inode(struct super_block *s)
1044{
1045 static const struct address_space_operations anon_aops = {
1046 .set_page_dirty = anon_set_page_dirty,
1047 };
1048 struct inode *inode = new_inode_pseudo(s);
1049
1050 if (!inode)
1051 return ERR_PTR(-ENOMEM);
1052
1053 inode->i_ino = get_next_ino();
1054 inode->i_mapping->a_ops = &anon_aops;
1055
1056 /*
1057 * Mark the inode dirty from the very beginning,
1058 * that way it will never be moved to the dirty
1059 * list because mark_inode_dirty() will think
1060 * that it already _is_ on the dirty list.
1061 */
1062 inode->i_state = I_DIRTY;
1063 inode->i_mode = S_IRUSR | S_IWUSR;
1064 inode->i_uid = current_fsuid();
1065 inode->i_gid = current_fsgid();
1066 inode->i_flags |= S_PRIVATE;
1067 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1068 return inode;
1069}
1070EXPORT_SYMBOL(alloc_anon_inode);
1071
1072/**
1073 * simple_nosetlease - generic helper for prohibiting leases
1074 * @filp: file pointer
1075 * @arg: type of lease to obtain
1076 * @flp: new lease supplied for insertion
1077 * @priv: private data for lm_setup operation
1078 *
1079 * Generic helper for filesystems that do not wish to allow leases to be set.
1080 * All arguments are ignored and it just returns -EINVAL.
1081 */
1082int
1083simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
1084 void **priv)
1085{
1086 return -EINVAL;
1087}
1088EXPORT_SYMBOL(simple_nosetlease);
1089
1090const char *simple_get_link(struct dentry *dentry, struct inode *inode,
1091 struct delayed_call *done)
1092{
1093 return inode->i_link;
1094}
1095EXPORT_SYMBOL(simple_get_link);
1096
1097const struct inode_operations simple_symlink_inode_operations = {
1098 .get_link = simple_get_link,
1099 .readlink = generic_readlink
1100};
1101EXPORT_SYMBOL(simple_symlink_inode_operations);
1102
1103/*
1104 * Operations for a permanently empty directory.
1105 */
1106static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
1107{
1108 return ERR_PTR(-ENOENT);
1109}
1110
1111static int empty_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
1112 struct kstat *stat)
1113{
1114 struct inode *inode = d_inode(dentry);
1115 generic_fillattr(inode, stat);
1116 return 0;
1117}
1118
1119static int empty_dir_setattr(struct dentry *dentry, struct iattr *attr)
1120{
1121 return -EPERM;
1122}
1123
1124static int empty_dir_setxattr(struct dentry *dentry, const char *name,
1125 const void *value, size_t size, int flags)
1126{
1127 return -EOPNOTSUPP;
1128}
1129
1130static ssize_t empty_dir_getxattr(struct dentry *dentry, const char *name,
1131 void *value, size_t size)
1132{
1133 return -EOPNOTSUPP;
1134}
1135
1136static int empty_dir_removexattr(struct dentry *dentry, const char *name)
1137{
1138 return -EOPNOTSUPP;
1139}
1140
1141static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
1142{
1143 return -EOPNOTSUPP;
1144}
1145
1146static const struct inode_operations empty_dir_inode_operations = {
1147 .lookup = empty_dir_lookup,
1148 .permission = generic_permission,
1149 .setattr = empty_dir_setattr,
1150 .getattr = empty_dir_getattr,
1151 .setxattr = empty_dir_setxattr,
1152 .getxattr = empty_dir_getxattr,
1153 .removexattr = empty_dir_removexattr,
1154 .listxattr = empty_dir_listxattr,
1155};
1156
1157static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
1158{
1159 /* An empty directory has two entries . and .. at offsets 0 and 1 */
1160 return generic_file_llseek_size(file, offset, whence, 2, 2);
1161}
1162
1163static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
1164{
1165 dir_emit_dots(file, ctx);
1166 return 0;
1167}
1168
1169static const struct file_operations empty_dir_operations = {
1170 .llseek = empty_dir_llseek,
1171 .read = generic_read_dir,
1172 .iterate = empty_dir_readdir,
1173 .fsync = noop_fsync,
1174};
1175
1176
1177void make_empty_dir_inode(struct inode *inode)
1178{
1179 set_nlink(inode, 2);
1180 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
1181 inode->i_uid = GLOBAL_ROOT_UID;
1182 inode->i_gid = GLOBAL_ROOT_GID;
1183 inode->i_rdev = 0;
1184 inode->i_size = 0;
1185 inode->i_blkbits = PAGE_SHIFT;
1186 inode->i_blocks = 0;
1187
1188 inode->i_op = &empty_dir_inode_operations;
1189 inode->i_fop = &empty_dir_operations;
1190}
1191
1192bool is_empty_dir_inode(struct inode *inode)
1193{
1194 return (inode->i_fop == &empty_dir_operations) &&
1195 (inode->i_op == &empty_dir_inode_operations);
1196}
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#include <linux/pidfs.h>
27
28#include <linux/uaccess.h>
29
30#include "internal.h"
31
32int simple_getattr(struct mnt_idmap *idmap, const struct path *path,
33 struct kstat *stat, u32 request_mask,
34 unsigned int query_flags)
35{
36 struct inode *inode = d_inode(path->dentry);
37 generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
38 stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
39 return 0;
40}
41EXPORT_SYMBOL(simple_getattr);
42
43int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
44{
45 u64 id = huge_encode_dev(dentry->d_sb->s_dev);
46
47 buf->f_fsid = u64_to_fsid(id);
48 buf->f_type = dentry->d_sb->s_magic;
49 buf->f_bsize = PAGE_SIZE;
50 buf->f_namelen = NAME_MAX;
51 return 0;
52}
53EXPORT_SYMBOL(simple_statfs);
54
55/*
56 * Retaining negative dentries for an in-memory filesystem just wastes
57 * memory and lookup time: arrange for them to be deleted immediately.
58 */
59int always_delete_dentry(const struct dentry *dentry)
60{
61 return 1;
62}
63EXPORT_SYMBOL(always_delete_dentry);
64
65const struct dentry_operations simple_dentry_operations = {
66 .d_delete = always_delete_dentry,
67};
68EXPORT_SYMBOL(simple_dentry_operations);
69
70/*
71 * Lookup the data. This is trivial - if the dentry didn't already
72 * exist, we know it is negative. Set d_op to delete negative dentries.
73 */
74struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
75{
76 if (dentry->d_name.len > NAME_MAX)
77 return ERR_PTR(-ENAMETOOLONG);
78 if (!dentry->d_sb->s_d_op)
79 d_set_d_op(dentry, &simple_dentry_operations);
80
81 if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
82 return NULL;
83
84 d_add(dentry, NULL);
85 return NULL;
86}
87EXPORT_SYMBOL(simple_lookup);
88
89int dcache_dir_open(struct inode *inode, struct file *file)
90{
91 file->private_data = d_alloc_cursor(file->f_path.dentry);
92
93 return file->private_data ? 0 : -ENOMEM;
94}
95EXPORT_SYMBOL(dcache_dir_open);
96
97int dcache_dir_close(struct inode *inode, struct file *file)
98{
99 dput(file->private_data);
100 return 0;
101}
102EXPORT_SYMBOL(dcache_dir_close);
103
104/* parent is locked at least shared */
105/*
106 * Returns an element of siblings' list.
107 * We are looking for <count>th positive after <p>; if
108 * found, dentry is grabbed and returned to caller.
109 * If no such element exists, NULL is returned.
110 */
111static struct dentry *scan_positives(struct dentry *cursor,
112 struct hlist_node **p,
113 loff_t count,
114 struct dentry *last)
115{
116 struct dentry *dentry = cursor->d_parent, *found = NULL;
117
118 spin_lock(&dentry->d_lock);
119 while (*p) {
120 struct dentry *d = hlist_entry(*p, struct dentry, d_sib);
121 p = &d->d_sib.next;
122 // we must at least skip cursors, to avoid livelocks
123 if (d->d_flags & DCACHE_DENTRY_CURSOR)
124 continue;
125 if (simple_positive(d) && !--count) {
126 spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
127 if (simple_positive(d))
128 found = dget_dlock(d);
129 spin_unlock(&d->d_lock);
130 if (likely(found))
131 break;
132 count = 1;
133 }
134 if (need_resched()) {
135 if (!hlist_unhashed(&cursor->d_sib))
136 __hlist_del(&cursor->d_sib);
137 hlist_add_behind(&cursor->d_sib, &d->d_sib);
138 p = &cursor->d_sib.next;
139 spin_unlock(&dentry->d_lock);
140 cond_resched();
141 spin_lock(&dentry->d_lock);
142 }
143 }
144 spin_unlock(&dentry->d_lock);
145 dput(last);
146 return found;
147}
148
149loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
150{
151 struct dentry *dentry = file->f_path.dentry;
152 switch (whence) {
153 case 1:
154 offset += file->f_pos;
155 fallthrough;
156 case 0:
157 if (offset >= 0)
158 break;
159 fallthrough;
160 default:
161 return -EINVAL;
162 }
163 if (offset != file->f_pos) {
164 struct dentry *cursor = file->private_data;
165 struct dentry *to = NULL;
166
167 inode_lock_shared(dentry->d_inode);
168
169 if (offset > 2)
170 to = scan_positives(cursor, &dentry->d_children.first,
171 offset - 2, NULL);
172 spin_lock(&dentry->d_lock);
173 hlist_del_init(&cursor->d_sib);
174 if (to)
175 hlist_add_behind(&cursor->d_sib, &to->d_sib);
176 spin_unlock(&dentry->d_lock);
177 dput(to);
178
179 file->f_pos = offset;
180
181 inode_unlock_shared(dentry->d_inode);
182 }
183 return offset;
184}
185EXPORT_SYMBOL(dcache_dir_lseek);
186
187/*
188 * Directory is locked and all positive dentries in it are safe, since
189 * for ramfs-type trees they can't go away without unlink() or rmdir(),
190 * both impossible due to the lock on directory.
191 */
192
193int dcache_readdir(struct file *file, struct dir_context *ctx)
194{
195 struct dentry *dentry = file->f_path.dentry;
196 struct dentry *cursor = file->private_data;
197 struct dentry *next = NULL;
198 struct hlist_node **p;
199
200 if (!dir_emit_dots(file, ctx))
201 return 0;
202
203 if (ctx->pos == 2)
204 p = &dentry->d_children.first;
205 else
206 p = &cursor->d_sib.next;
207
208 while ((next = scan_positives(cursor, p, 1, next)) != NULL) {
209 if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
210 d_inode(next)->i_ino,
211 fs_umode_to_dtype(d_inode(next)->i_mode)))
212 break;
213 ctx->pos++;
214 p = &next->d_sib.next;
215 }
216 spin_lock(&dentry->d_lock);
217 hlist_del_init(&cursor->d_sib);
218 if (next)
219 hlist_add_before(&cursor->d_sib, &next->d_sib);
220 spin_unlock(&dentry->d_lock);
221 dput(next);
222
223 return 0;
224}
225EXPORT_SYMBOL(dcache_readdir);
226
227ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
228{
229 return -EISDIR;
230}
231EXPORT_SYMBOL(generic_read_dir);
232
233const struct file_operations simple_dir_operations = {
234 .open = dcache_dir_open,
235 .release = dcache_dir_close,
236 .llseek = dcache_dir_lseek,
237 .read = generic_read_dir,
238 .iterate_shared = dcache_readdir,
239 .fsync = noop_fsync,
240};
241EXPORT_SYMBOL(simple_dir_operations);
242
243const struct inode_operations simple_dir_inode_operations = {
244 .lookup = simple_lookup,
245};
246EXPORT_SYMBOL(simple_dir_inode_operations);
247
248/* simple_offset_add() never assigns these to a dentry */
249enum {
250 DIR_OFFSET_FIRST = 2, /* Find first real entry */
251 DIR_OFFSET_EOD = S32_MAX,
252};
253
254/* simple_offset_add() allocation range */
255enum {
256 DIR_OFFSET_MIN = DIR_OFFSET_FIRST + 1,
257 DIR_OFFSET_MAX = DIR_OFFSET_EOD - 1,
258};
259
260static void offset_set(struct dentry *dentry, long offset)
261{
262 dentry->d_fsdata = (void *)offset;
263}
264
265static long dentry2offset(struct dentry *dentry)
266{
267 return (long)dentry->d_fsdata;
268}
269
270static struct lock_class_key simple_offset_lock_class;
271
272/**
273 * simple_offset_init - initialize an offset_ctx
274 * @octx: directory offset map to be initialized
275 *
276 */
277void simple_offset_init(struct offset_ctx *octx)
278{
279 mt_init_flags(&octx->mt, MT_FLAGS_ALLOC_RANGE);
280 lockdep_set_class(&octx->mt.ma_lock, &simple_offset_lock_class);
281 octx->next_offset = DIR_OFFSET_MIN;
282}
283
284/**
285 * simple_offset_add - Add an entry to a directory's offset map
286 * @octx: directory offset ctx to be updated
287 * @dentry: new dentry being added
288 *
289 * Returns zero on success. @octx and the dentry's offset are updated.
290 * Otherwise, a negative errno value is returned.
291 */
292int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry)
293{
294 unsigned long offset;
295 int ret;
296
297 if (dentry2offset(dentry) != 0)
298 return -EBUSY;
299
300 ret = mtree_alloc_cyclic(&octx->mt, &offset, dentry, DIR_OFFSET_MIN,
301 DIR_OFFSET_MAX, &octx->next_offset,
302 GFP_KERNEL);
303 if (unlikely(ret < 0))
304 return ret == -EBUSY ? -ENOSPC : ret;
305
306 offset_set(dentry, offset);
307 return 0;
308}
309
310static int simple_offset_replace(struct offset_ctx *octx, struct dentry *dentry,
311 long offset)
312{
313 int ret;
314
315 ret = mtree_store(&octx->mt, offset, dentry, GFP_KERNEL);
316 if (ret)
317 return ret;
318 offset_set(dentry, offset);
319 return 0;
320}
321
322/**
323 * simple_offset_remove - Remove an entry to a directory's offset map
324 * @octx: directory offset ctx to be updated
325 * @dentry: dentry being removed
326 *
327 */
328void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry)
329{
330 long offset;
331
332 offset = dentry2offset(dentry);
333 if (offset == 0)
334 return;
335
336 mtree_erase(&octx->mt, offset);
337 offset_set(dentry, 0);
338}
339
340/**
341 * simple_offset_rename - handle directory offsets for rename
342 * @old_dir: parent directory of source entry
343 * @old_dentry: dentry of source entry
344 * @new_dir: parent_directory of destination entry
345 * @new_dentry: dentry of destination
346 *
347 * Caller provides appropriate serialization.
348 *
349 * User space expects the directory offset value of the replaced
350 * (new) directory entry to be unchanged after a rename.
351 *
352 * Returns zero on success, a negative errno value on failure.
353 */
354int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
355 struct inode *new_dir, struct dentry *new_dentry)
356{
357 struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir);
358 struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir);
359 long new_offset = dentry2offset(new_dentry);
360
361 simple_offset_remove(old_ctx, old_dentry);
362
363 if (new_offset) {
364 offset_set(new_dentry, 0);
365 return simple_offset_replace(new_ctx, old_dentry, new_offset);
366 }
367 return simple_offset_add(new_ctx, old_dentry);
368}
369
370/**
371 * simple_offset_rename_exchange - exchange rename with directory offsets
372 * @old_dir: parent of dentry being moved
373 * @old_dentry: dentry being moved
374 * @new_dir: destination parent
375 * @new_dentry: destination dentry
376 *
377 * This API preserves the directory offset values. Caller provides
378 * appropriate serialization.
379 *
380 * Returns zero on success. Otherwise a negative errno is returned and the
381 * rename is rolled back.
382 */
383int simple_offset_rename_exchange(struct inode *old_dir,
384 struct dentry *old_dentry,
385 struct inode *new_dir,
386 struct dentry *new_dentry)
387{
388 struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir);
389 struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir);
390 long old_index = dentry2offset(old_dentry);
391 long new_index = dentry2offset(new_dentry);
392 int ret;
393
394 simple_offset_remove(old_ctx, old_dentry);
395 simple_offset_remove(new_ctx, new_dentry);
396
397 ret = simple_offset_replace(new_ctx, old_dentry, new_index);
398 if (ret)
399 goto out_restore;
400
401 ret = simple_offset_replace(old_ctx, new_dentry, old_index);
402 if (ret) {
403 simple_offset_remove(new_ctx, old_dentry);
404 goto out_restore;
405 }
406
407 ret = simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
408 if (ret) {
409 simple_offset_remove(new_ctx, old_dentry);
410 simple_offset_remove(old_ctx, new_dentry);
411 goto out_restore;
412 }
413 return 0;
414
415out_restore:
416 (void)simple_offset_replace(old_ctx, old_dentry, old_index);
417 (void)simple_offset_replace(new_ctx, new_dentry, new_index);
418 return ret;
419}
420
421/**
422 * simple_offset_destroy - Release offset map
423 * @octx: directory offset ctx that is about to be destroyed
424 *
425 * During fs teardown (eg. umount), a directory's offset map might still
426 * contain entries. xa_destroy() cleans out anything that remains.
427 */
428void simple_offset_destroy(struct offset_ctx *octx)
429{
430 mtree_destroy(&octx->mt);
431}
432
433/**
434 * offset_dir_llseek - Advance the read position of a directory descriptor
435 * @file: an open directory whose position is to be updated
436 * @offset: a byte offset
437 * @whence: enumerator describing the starting position for this update
438 *
439 * SEEK_END, SEEK_DATA, and SEEK_HOLE are not supported for directories.
440 *
441 * Returns the updated read position if successful; otherwise a
442 * negative errno is returned and the read position remains unchanged.
443 */
444static loff_t offset_dir_llseek(struct file *file, loff_t offset, int whence)
445{
446 switch (whence) {
447 case SEEK_CUR:
448 offset += file->f_pos;
449 fallthrough;
450 case SEEK_SET:
451 if (offset >= 0)
452 break;
453 fallthrough;
454 default:
455 return -EINVAL;
456 }
457
458 return vfs_setpos(file, offset, LONG_MAX);
459}
460
461static struct dentry *find_positive_dentry(struct dentry *parent,
462 struct dentry *dentry,
463 bool next)
464{
465 struct dentry *found = NULL;
466
467 spin_lock(&parent->d_lock);
468 if (next)
469 dentry = d_next_sibling(dentry);
470 else if (!dentry)
471 dentry = d_first_child(parent);
472 hlist_for_each_entry_from(dentry, d_sib) {
473 if (!simple_positive(dentry))
474 continue;
475 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
476 if (simple_positive(dentry))
477 found = dget_dlock(dentry);
478 spin_unlock(&dentry->d_lock);
479 if (likely(found))
480 break;
481 }
482 spin_unlock(&parent->d_lock);
483 return found;
484}
485
486static noinline_for_stack struct dentry *
487offset_dir_lookup(struct dentry *parent, loff_t offset)
488{
489 struct inode *inode = d_inode(parent);
490 struct offset_ctx *octx = inode->i_op->get_offset_ctx(inode);
491 struct dentry *child, *found = NULL;
492
493 MA_STATE(mas, &octx->mt, offset, offset);
494
495 if (offset == DIR_OFFSET_FIRST)
496 found = find_positive_dentry(parent, NULL, false);
497 else {
498 rcu_read_lock();
499 child = mas_find(&mas, DIR_OFFSET_MAX);
500 found = find_positive_dentry(parent, child, false);
501 rcu_read_unlock();
502 }
503 return found;
504}
505
506static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry)
507{
508 struct inode *inode = d_inode(dentry);
509
510 return dir_emit(ctx, dentry->d_name.name, dentry->d_name.len,
511 inode->i_ino, fs_umode_to_dtype(inode->i_mode));
512}
513
514static void offset_iterate_dir(struct file *file, struct dir_context *ctx)
515{
516 struct dentry *dir = file->f_path.dentry;
517 struct dentry *dentry;
518
519 dentry = offset_dir_lookup(dir, ctx->pos);
520 if (!dentry)
521 goto out_eod;
522 while (true) {
523 struct dentry *next;
524
525 ctx->pos = dentry2offset(dentry);
526 if (!offset_dir_emit(ctx, dentry))
527 break;
528
529 next = find_positive_dentry(dir, dentry, true);
530 dput(dentry);
531
532 if (!next)
533 goto out_eod;
534 dentry = next;
535 }
536 dput(dentry);
537 return;
538
539out_eod:
540 ctx->pos = DIR_OFFSET_EOD;
541}
542
543/**
544 * offset_readdir - Emit entries starting at offset @ctx->pos
545 * @file: an open directory to iterate over
546 * @ctx: directory iteration context
547 *
548 * Caller must hold @file's i_rwsem to prevent insertion or removal of
549 * entries during this call.
550 *
551 * On entry, @ctx->pos contains an offset that represents the first entry
552 * to be read from the directory.
553 *
554 * The operation continues until there are no more entries to read, or
555 * until the ctx->actor indicates there is no more space in the caller's
556 * output buffer.
557 *
558 * On return, @ctx->pos contains an offset that will read the next entry
559 * in this directory when offset_readdir() is called again with @ctx.
560 * Caller places this value in the d_off field of the last entry in the
561 * user's buffer.
562 *
563 * Return values:
564 * %0 - Complete
565 */
566static int offset_readdir(struct file *file, struct dir_context *ctx)
567{
568 struct dentry *dir = file->f_path.dentry;
569
570 lockdep_assert_held(&d_inode(dir)->i_rwsem);
571
572 if (!dir_emit_dots(file, ctx))
573 return 0;
574 if (ctx->pos != DIR_OFFSET_EOD)
575 offset_iterate_dir(file, ctx);
576 return 0;
577}
578
579const struct file_operations simple_offset_dir_operations = {
580 .llseek = offset_dir_llseek,
581 .iterate_shared = offset_readdir,
582 .read = generic_read_dir,
583 .fsync = noop_fsync,
584};
585
586static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev)
587{
588 struct dentry *child = NULL, *d;
589
590 spin_lock(&parent->d_lock);
591 d = prev ? d_next_sibling(prev) : d_first_child(parent);
592 hlist_for_each_entry_from(d, d_sib) {
593 if (simple_positive(d)) {
594 spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
595 if (simple_positive(d))
596 child = dget_dlock(d);
597 spin_unlock(&d->d_lock);
598 if (likely(child))
599 break;
600 }
601 }
602 spin_unlock(&parent->d_lock);
603 dput(prev);
604 return child;
605}
606
607void simple_recursive_removal(struct dentry *dentry,
608 void (*callback)(struct dentry *))
609{
610 struct dentry *this = dget(dentry);
611 while (true) {
612 struct dentry *victim = NULL, *child;
613 struct inode *inode = this->d_inode;
614
615 inode_lock(inode);
616 if (d_is_dir(this))
617 inode->i_flags |= S_DEAD;
618 while ((child = find_next_child(this, victim)) == NULL) {
619 // kill and ascend
620 // update metadata while it's still locked
621 inode_set_ctime_current(inode);
622 clear_nlink(inode);
623 inode_unlock(inode);
624 victim = this;
625 this = this->d_parent;
626 inode = this->d_inode;
627 inode_lock(inode);
628 if (simple_positive(victim)) {
629 d_invalidate(victim); // avoid lost mounts
630 if (d_is_dir(victim))
631 fsnotify_rmdir(inode, victim);
632 else
633 fsnotify_unlink(inode, victim);
634 if (callback)
635 callback(victim);
636 dput(victim); // unpin it
637 }
638 if (victim == dentry) {
639 inode_set_mtime_to_ts(inode,
640 inode_set_ctime_current(inode));
641 if (d_is_dir(dentry))
642 drop_nlink(inode);
643 inode_unlock(inode);
644 dput(dentry);
645 return;
646 }
647 }
648 inode_unlock(inode);
649 this = child;
650 }
651}
652EXPORT_SYMBOL(simple_recursive_removal);
653
654static const struct super_operations simple_super_operations = {
655 .statfs = simple_statfs,
656};
657
658static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc)
659{
660 struct pseudo_fs_context *ctx = fc->fs_private;
661 struct inode *root;
662
663 s->s_maxbytes = MAX_LFS_FILESIZE;
664 s->s_blocksize = PAGE_SIZE;
665 s->s_blocksize_bits = PAGE_SHIFT;
666 s->s_magic = ctx->magic;
667 s->s_op = ctx->ops ?: &simple_super_operations;
668 s->s_xattr = ctx->xattr;
669 s->s_time_gran = 1;
670 root = new_inode(s);
671 if (!root)
672 return -ENOMEM;
673
674 /*
675 * since this is the first inode, make it number 1. New inodes created
676 * after this must take care not to collide with it (by passing
677 * max_reserved of 1 to iunique).
678 */
679 root->i_ino = 1;
680 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
681 simple_inode_init_ts(root);
682 s->s_root = d_make_root(root);
683 if (!s->s_root)
684 return -ENOMEM;
685 s->s_d_op = ctx->dops;
686 return 0;
687}
688
689static int pseudo_fs_get_tree(struct fs_context *fc)
690{
691 return get_tree_nodev(fc, pseudo_fs_fill_super);
692}
693
694static void pseudo_fs_free(struct fs_context *fc)
695{
696 kfree(fc->fs_private);
697}
698
699static const struct fs_context_operations pseudo_fs_context_ops = {
700 .free = pseudo_fs_free,
701 .get_tree = pseudo_fs_get_tree,
702};
703
704/*
705 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
706 * will never be mountable)
707 */
708struct pseudo_fs_context *init_pseudo(struct fs_context *fc,
709 unsigned long magic)
710{
711 struct pseudo_fs_context *ctx;
712
713 ctx = kzalloc(sizeof(struct pseudo_fs_context), GFP_KERNEL);
714 if (likely(ctx)) {
715 ctx->magic = magic;
716 fc->fs_private = ctx;
717 fc->ops = &pseudo_fs_context_ops;
718 fc->sb_flags |= SB_NOUSER;
719 fc->global = true;
720 }
721 return ctx;
722}
723EXPORT_SYMBOL(init_pseudo);
724
725int simple_open(struct inode *inode, struct file *file)
726{
727 if (inode->i_private)
728 file->private_data = inode->i_private;
729 return 0;
730}
731EXPORT_SYMBOL(simple_open);
732
733int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
734{
735 struct inode *inode = d_inode(old_dentry);
736
737 inode_set_mtime_to_ts(dir,
738 inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
739 inc_nlink(inode);
740 ihold(inode);
741 dget(dentry);
742 d_instantiate(dentry, inode);
743 return 0;
744}
745EXPORT_SYMBOL(simple_link);
746
747int simple_empty(struct dentry *dentry)
748{
749 struct dentry *child;
750 int ret = 0;
751
752 spin_lock(&dentry->d_lock);
753 hlist_for_each_entry(child, &dentry->d_children, d_sib) {
754 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
755 if (simple_positive(child)) {
756 spin_unlock(&child->d_lock);
757 goto out;
758 }
759 spin_unlock(&child->d_lock);
760 }
761 ret = 1;
762out:
763 spin_unlock(&dentry->d_lock);
764 return ret;
765}
766EXPORT_SYMBOL(simple_empty);
767
768int simple_unlink(struct inode *dir, struct dentry *dentry)
769{
770 struct inode *inode = d_inode(dentry);
771
772 inode_set_mtime_to_ts(dir,
773 inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
774 drop_nlink(inode);
775 dput(dentry);
776 return 0;
777}
778EXPORT_SYMBOL(simple_unlink);
779
780int simple_rmdir(struct inode *dir, struct dentry *dentry)
781{
782 if (!simple_empty(dentry))
783 return -ENOTEMPTY;
784
785 drop_nlink(d_inode(dentry));
786 simple_unlink(dir, dentry);
787 drop_nlink(dir);
788 return 0;
789}
790EXPORT_SYMBOL(simple_rmdir);
791
792/**
793 * simple_rename_timestamp - update the various inode timestamps for rename
794 * @old_dir: old parent directory
795 * @old_dentry: dentry that is being renamed
796 * @new_dir: new parent directory
797 * @new_dentry: target for rename
798 *
799 * POSIX mandates that the old and new parent directories have their ctime and
800 * mtime updated, and that inodes of @old_dentry and @new_dentry (if any), have
801 * their ctime updated.
802 */
803void simple_rename_timestamp(struct inode *old_dir, struct dentry *old_dentry,
804 struct inode *new_dir, struct dentry *new_dentry)
805{
806 struct inode *newino = d_inode(new_dentry);
807
808 inode_set_mtime_to_ts(old_dir, inode_set_ctime_current(old_dir));
809 if (new_dir != old_dir)
810 inode_set_mtime_to_ts(new_dir,
811 inode_set_ctime_current(new_dir));
812 inode_set_ctime_current(d_inode(old_dentry));
813 if (newino)
814 inode_set_ctime_current(newino);
815}
816EXPORT_SYMBOL_GPL(simple_rename_timestamp);
817
818int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry,
819 struct inode *new_dir, struct dentry *new_dentry)
820{
821 bool old_is_dir = d_is_dir(old_dentry);
822 bool new_is_dir = d_is_dir(new_dentry);
823
824 if (old_dir != new_dir && old_is_dir != new_is_dir) {
825 if (old_is_dir) {
826 drop_nlink(old_dir);
827 inc_nlink(new_dir);
828 } else {
829 drop_nlink(new_dir);
830 inc_nlink(old_dir);
831 }
832 }
833 simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
834 return 0;
835}
836EXPORT_SYMBOL_GPL(simple_rename_exchange);
837
838int simple_rename(struct mnt_idmap *idmap, struct inode *old_dir,
839 struct dentry *old_dentry, struct inode *new_dir,
840 struct dentry *new_dentry, unsigned int flags)
841{
842 int they_are_dirs = d_is_dir(old_dentry);
843
844 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
845 return -EINVAL;
846
847 if (flags & RENAME_EXCHANGE)
848 return simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
849
850 if (!simple_empty(new_dentry))
851 return -ENOTEMPTY;
852
853 if (d_really_is_positive(new_dentry)) {
854 simple_unlink(new_dir, new_dentry);
855 if (they_are_dirs) {
856 drop_nlink(d_inode(new_dentry));
857 drop_nlink(old_dir);
858 }
859 } else if (they_are_dirs) {
860 drop_nlink(old_dir);
861 inc_nlink(new_dir);
862 }
863
864 simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
865 return 0;
866}
867EXPORT_SYMBOL(simple_rename);
868
869/**
870 * simple_setattr - setattr for simple filesystem
871 * @idmap: idmap of the target mount
872 * @dentry: dentry
873 * @iattr: iattr structure
874 *
875 * Returns 0 on success, -error on failure.
876 *
877 * simple_setattr is a simple ->setattr implementation without a proper
878 * implementation of size changes.
879 *
880 * It can either be used for in-memory filesystems or special files
881 * on simple regular filesystems. Anything that needs to change on-disk
882 * or wire state on size changes needs its own setattr method.
883 */
884int simple_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
885 struct iattr *iattr)
886{
887 struct inode *inode = d_inode(dentry);
888 int error;
889
890 error = setattr_prepare(idmap, dentry, iattr);
891 if (error)
892 return error;
893
894 if (iattr->ia_valid & ATTR_SIZE)
895 truncate_setsize(inode, iattr->ia_size);
896 setattr_copy(idmap, inode, iattr);
897 mark_inode_dirty(inode);
898 return 0;
899}
900EXPORT_SYMBOL(simple_setattr);
901
902static int simple_read_folio(struct file *file, struct folio *folio)
903{
904 folio_zero_range(folio, 0, folio_size(folio));
905 flush_dcache_folio(folio);
906 folio_mark_uptodate(folio);
907 folio_unlock(folio);
908 return 0;
909}
910
911int simple_write_begin(struct file *file, struct address_space *mapping,
912 loff_t pos, unsigned len,
913 struct folio **foliop, void **fsdata)
914{
915 struct folio *folio;
916
917 folio = __filemap_get_folio(mapping, pos / PAGE_SIZE, FGP_WRITEBEGIN,
918 mapping_gfp_mask(mapping));
919 if (IS_ERR(folio))
920 return PTR_ERR(folio);
921
922 *foliop = folio;
923
924 if (!folio_test_uptodate(folio) && (len != folio_size(folio))) {
925 size_t from = offset_in_folio(folio, pos);
926
927 folio_zero_segments(folio, 0, from,
928 from + len, folio_size(folio));
929 }
930 return 0;
931}
932EXPORT_SYMBOL(simple_write_begin);
933
934/**
935 * simple_write_end - .write_end helper for non-block-device FSes
936 * @file: See .write_end of address_space_operations
937 * @mapping: "
938 * @pos: "
939 * @len: "
940 * @copied: "
941 * @folio: "
942 * @fsdata: "
943 *
944 * simple_write_end does the minimum needed for updating a folio after
945 * writing is done. It has the same API signature as the .write_end of
946 * address_space_operations vector. So it can just be set onto .write_end for
947 * FSes that don't need any other processing. i_mutex is assumed to be held.
948 * Block based filesystems should use generic_write_end().
949 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
950 * is not called, so a filesystem that actually does store data in .write_inode
951 * should extend on what's done here with a call to mark_inode_dirty() in the
952 * case that i_size has changed.
953 *
954 * Use *ONLY* with simple_read_folio()
955 */
956static int simple_write_end(struct file *file, struct address_space *mapping,
957 loff_t pos, unsigned len, unsigned copied,
958 struct folio *folio, void *fsdata)
959{
960 struct inode *inode = folio->mapping->host;
961 loff_t last_pos = pos + copied;
962
963 /* zero the stale part of the folio if we did a short copy */
964 if (!folio_test_uptodate(folio)) {
965 if (copied < len) {
966 size_t from = offset_in_folio(folio, pos);
967
968 folio_zero_range(folio, from + copied, len - copied);
969 }
970 folio_mark_uptodate(folio);
971 }
972 /*
973 * No need to use i_size_read() here, the i_size
974 * cannot change under us because we hold the i_mutex.
975 */
976 if (last_pos > inode->i_size)
977 i_size_write(inode, last_pos);
978
979 folio_mark_dirty(folio);
980 folio_unlock(folio);
981 folio_put(folio);
982
983 return copied;
984}
985
986/*
987 * Provides ramfs-style behavior: data in the pagecache, but no writeback.
988 */
989const struct address_space_operations ram_aops = {
990 .read_folio = simple_read_folio,
991 .write_begin = simple_write_begin,
992 .write_end = simple_write_end,
993 .dirty_folio = noop_dirty_folio,
994};
995EXPORT_SYMBOL(ram_aops);
996
997/*
998 * the inodes created here are not hashed. If you use iunique to generate
999 * unique inode values later for this filesystem, then you must take care
1000 * to pass it an appropriate max_reserved value to avoid collisions.
1001 */
1002int simple_fill_super(struct super_block *s, unsigned long magic,
1003 const struct tree_descr *files)
1004{
1005 struct inode *inode;
1006 struct dentry *dentry;
1007 int i;
1008
1009 s->s_blocksize = PAGE_SIZE;
1010 s->s_blocksize_bits = PAGE_SHIFT;
1011 s->s_magic = magic;
1012 s->s_op = &simple_super_operations;
1013 s->s_time_gran = 1;
1014
1015 inode = new_inode(s);
1016 if (!inode)
1017 return -ENOMEM;
1018 /*
1019 * because the root inode is 1, the files array must not contain an
1020 * entry at index 1
1021 */
1022 inode->i_ino = 1;
1023 inode->i_mode = S_IFDIR | 0755;
1024 simple_inode_init_ts(inode);
1025 inode->i_op = &simple_dir_inode_operations;
1026 inode->i_fop = &simple_dir_operations;
1027 set_nlink(inode, 2);
1028 s->s_root = d_make_root(inode);
1029 if (!s->s_root)
1030 return -ENOMEM;
1031 for (i = 0; !files->name || files->name[0]; i++, files++) {
1032 if (!files->name)
1033 continue;
1034
1035 /* warn if it tries to conflict with the root inode */
1036 if (unlikely(i == 1))
1037 printk(KERN_WARNING "%s: %s passed in a files array"
1038 "with an index of 1!\n", __func__,
1039 s->s_type->name);
1040
1041 dentry = d_alloc_name(s->s_root, files->name);
1042 if (!dentry)
1043 return -ENOMEM;
1044 inode = new_inode(s);
1045 if (!inode) {
1046 dput(dentry);
1047 return -ENOMEM;
1048 }
1049 inode->i_mode = S_IFREG | files->mode;
1050 simple_inode_init_ts(inode);
1051 inode->i_fop = files->ops;
1052 inode->i_ino = i;
1053 d_add(dentry, inode);
1054 }
1055 return 0;
1056}
1057EXPORT_SYMBOL(simple_fill_super);
1058
1059static DEFINE_SPINLOCK(pin_fs_lock);
1060
1061int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
1062{
1063 struct vfsmount *mnt = NULL;
1064 spin_lock(&pin_fs_lock);
1065 if (unlikely(!*mount)) {
1066 spin_unlock(&pin_fs_lock);
1067 mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
1068 if (IS_ERR(mnt))
1069 return PTR_ERR(mnt);
1070 spin_lock(&pin_fs_lock);
1071 if (!*mount)
1072 *mount = mnt;
1073 }
1074 mntget(*mount);
1075 ++*count;
1076 spin_unlock(&pin_fs_lock);
1077 mntput(mnt);
1078 return 0;
1079}
1080EXPORT_SYMBOL(simple_pin_fs);
1081
1082void simple_release_fs(struct vfsmount **mount, int *count)
1083{
1084 struct vfsmount *mnt;
1085 spin_lock(&pin_fs_lock);
1086 mnt = *mount;
1087 if (!--*count)
1088 *mount = NULL;
1089 spin_unlock(&pin_fs_lock);
1090 mntput(mnt);
1091}
1092EXPORT_SYMBOL(simple_release_fs);
1093
1094/**
1095 * simple_read_from_buffer - copy data from the buffer to user space
1096 * @to: the user space buffer to read to
1097 * @count: the maximum number of bytes to read
1098 * @ppos: the current position in the buffer
1099 * @from: the buffer to read from
1100 * @available: the size of the buffer
1101 *
1102 * The simple_read_from_buffer() function reads up to @count bytes from the
1103 * buffer @from at offset @ppos into the user space address starting at @to.
1104 *
1105 * On success, the number of bytes read is returned and the offset @ppos is
1106 * advanced by this number, or negative value is returned on error.
1107 **/
1108ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
1109 const void *from, size_t available)
1110{
1111 loff_t pos = *ppos;
1112 size_t ret;
1113
1114 if (pos < 0)
1115 return -EINVAL;
1116 if (pos >= available || !count)
1117 return 0;
1118 if (count > available - pos)
1119 count = available - pos;
1120 ret = copy_to_user(to, from + pos, count);
1121 if (ret == count)
1122 return -EFAULT;
1123 count -= ret;
1124 *ppos = pos + count;
1125 return count;
1126}
1127EXPORT_SYMBOL(simple_read_from_buffer);
1128
1129/**
1130 * simple_write_to_buffer - copy data from user space to the buffer
1131 * @to: the buffer to write to
1132 * @available: the size of the buffer
1133 * @ppos: the current position in the buffer
1134 * @from: the user space buffer to read from
1135 * @count: the maximum number of bytes to read
1136 *
1137 * The simple_write_to_buffer() function reads up to @count bytes from the user
1138 * space address starting at @from into the buffer @to at offset @ppos.
1139 *
1140 * On success, the number of bytes written is returned and the offset @ppos is
1141 * advanced by this number, or negative value is returned on error.
1142 **/
1143ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
1144 const void __user *from, size_t count)
1145{
1146 loff_t pos = *ppos;
1147 size_t res;
1148
1149 if (pos < 0)
1150 return -EINVAL;
1151 if (pos >= available || !count)
1152 return 0;
1153 if (count > available - pos)
1154 count = available - pos;
1155 res = copy_from_user(to + pos, from, count);
1156 if (res == count)
1157 return -EFAULT;
1158 count -= res;
1159 *ppos = pos + count;
1160 return count;
1161}
1162EXPORT_SYMBOL(simple_write_to_buffer);
1163
1164/**
1165 * memory_read_from_buffer - copy data from the buffer
1166 * @to: the kernel space buffer to read to
1167 * @count: the maximum number of bytes to read
1168 * @ppos: the current position in the buffer
1169 * @from: the buffer to read from
1170 * @available: the size of the buffer
1171 *
1172 * The memory_read_from_buffer() function reads up to @count bytes from the
1173 * buffer @from at offset @ppos into the kernel space address starting at @to.
1174 *
1175 * On success, the number of bytes read is returned and the offset @ppos is
1176 * advanced by this number, or negative value is returned on error.
1177 **/
1178ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
1179 const void *from, size_t available)
1180{
1181 loff_t pos = *ppos;
1182
1183 if (pos < 0)
1184 return -EINVAL;
1185 if (pos >= available)
1186 return 0;
1187 if (count > available - pos)
1188 count = available - pos;
1189 memcpy(to, from + pos, count);
1190 *ppos = pos + count;
1191
1192 return count;
1193}
1194EXPORT_SYMBOL(memory_read_from_buffer);
1195
1196/*
1197 * Transaction based IO.
1198 * The file expects a single write which triggers the transaction, and then
1199 * possibly a read which collects the result - which is stored in a
1200 * file-local buffer.
1201 */
1202
1203void simple_transaction_set(struct file *file, size_t n)
1204{
1205 struct simple_transaction_argresp *ar = file->private_data;
1206
1207 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
1208
1209 /*
1210 * The barrier ensures that ar->size will really remain zero until
1211 * ar->data is ready for reading.
1212 */
1213 smp_mb();
1214 ar->size = n;
1215}
1216EXPORT_SYMBOL(simple_transaction_set);
1217
1218char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
1219{
1220 struct simple_transaction_argresp *ar;
1221 static DEFINE_SPINLOCK(simple_transaction_lock);
1222
1223 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
1224 return ERR_PTR(-EFBIG);
1225
1226 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
1227 if (!ar)
1228 return ERR_PTR(-ENOMEM);
1229
1230 spin_lock(&simple_transaction_lock);
1231
1232 /* only one write allowed per open */
1233 if (file->private_data) {
1234 spin_unlock(&simple_transaction_lock);
1235 free_page((unsigned long)ar);
1236 return ERR_PTR(-EBUSY);
1237 }
1238
1239 file->private_data = ar;
1240
1241 spin_unlock(&simple_transaction_lock);
1242
1243 if (copy_from_user(ar->data, buf, size))
1244 return ERR_PTR(-EFAULT);
1245
1246 return ar->data;
1247}
1248EXPORT_SYMBOL(simple_transaction_get);
1249
1250ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
1251{
1252 struct simple_transaction_argresp *ar = file->private_data;
1253
1254 if (!ar)
1255 return 0;
1256 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
1257}
1258EXPORT_SYMBOL(simple_transaction_read);
1259
1260int simple_transaction_release(struct inode *inode, struct file *file)
1261{
1262 free_page((unsigned long)file->private_data);
1263 return 0;
1264}
1265EXPORT_SYMBOL(simple_transaction_release);
1266
1267/* Simple attribute files */
1268
1269struct simple_attr {
1270 int (*get)(void *, u64 *);
1271 int (*set)(void *, u64);
1272 char get_buf[24]; /* enough to store a u64 and "\n\0" */
1273 char set_buf[24];
1274 void *data;
1275 const char *fmt; /* format for read operation */
1276 struct mutex mutex; /* protects access to these buffers */
1277};
1278
1279/* simple_attr_open is called by an actual attribute open file operation
1280 * to set the attribute specific access operations. */
1281int simple_attr_open(struct inode *inode, struct file *file,
1282 int (*get)(void *, u64 *), int (*set)(void *, u64),
1283 const char *fmt)
1284{
1285 struct simple_attr *attr;
1286
1287 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
1288 if (!attr)
1289 return -ENOMEM;
1290
1291 attr->get = get;
1292 attr->set = set;
1293 attr->data = inode->i_private;
1294 attr->fmt = fmt;
1295 mutex_init(&attr->mutex);
1296
1297 file->private_data = attr;
1298
1299 return nonseekable_open(inode, file);
1300}
1301EXPORT_SYMBOL_GPL(simple_attr_open);
1302
1303int simple_attr_release(struct inode *inode, struct file *file)
1304{
1305 kfree(file->private_data);
1306 return 0;
1307}
1308EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
1309
1310/* read from the buffer that is filled with the get function */
1311ssize_t simple_attr_read(struct file *file, char __user *buf,
1312 size_t len, loff_t *ppos)
1313{
1314 struct simple_attr *attr;
1315 size_t size;
1316 ssize_t ret;
1317
1318 attr = file->private_data;
1319
1320 if (!attr->get)
1321 return -EACCES;
1322
1323 ret = mutex_lock_interruptible(&attr->mutex);
1324 if (ret)
1325 return ret;
1326
1327 if (*ppos && attr->get_buf[0]) {
1328 /* continued read */
1329 size = strlen(attr->get_buf);
1330 } else {
1331 /* first read */
1332 u64 val;
1333 ret = attr->get(attr->data, &val);
1334 if (ret)
1335 goto out;
1336
1337 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
1338 attr->fmt, (unsigned long long)val);
1339 }
1340
1341 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
1342out:
1343 mutex_unlock(&attr->mutex);
1344 return ret;
1345}
1346EXPORT_SYMBOL_GPL(simple_attr_read);
1347
1348/* interpret the buffer as a number to call the set function with */
1349static ssize_t simple_attr_write_xsigned(struct file *file, const char __user *buf,
1350 size_t len, loff_t *ppos, bool is_signed)
1351{
1352 struct simple_attr *attr;
1353 unsigned long long val;
1354 size_t size;
1355 ssize_t ret;
1356
1357 attr = file->private_data;
1358 if (!attr->set)
1359 return -EACCES;
1360
1361 ret = mutex_lock_interruptible(&attr->mutex);
1362 if (ret)
1363 return ret;
1364
1365 ret = -EFAULT;
1366 size = min(sizeof(attr->set_buf) - 1, len);
1367 if (copy_from_user(attr->set_buf, buf, size))
1368 goto out;
1369
1370 attr->set_buf[size] = '\0';
1371 if (is_signed)
1372 ret = kstrtoll(attr->set_buf, 0, &val);
1373 else
1374 ret = kstrtoull(attr->set_buf, 0, &val);
1375 if (ret)
1376 goto out;
1377 ret = attr->set(attr->data, val);
1378 if (ret == 0)
1379 ret = len; /* on success, claim we got the whole input */
1380out:
1381 mutex_unlock(&attr->mutex);
1382 return ret;
1383}
1384
1385ssize_t simple_attr_write(struct file *file, const char __user *buf,
1386 size_t len, loff_t *ppos)
1387{
1388 return simple_attr_write_xsigned(file, buf, len, ppos, false);
1389}
1390EXPORT_SYMBOL_GPL(simple_attr_write);
1391
1392ssize_t simple_attr_write_signed(struct file *file, const char __user *buf,
1393 size_t len, loff_t *ppos)
1394{
1395 return simple_attr_write_xsigned(file, buf, len, ppos, true);
1396}
1397EXPORT_SYMBOL_GPL(simple_attr_write_signed);
1398
1399/**
1400 * generic_encode_ino32_fh - generic export_operations->encode_fh function
1401 * @inode: the object to encode
1402 * @fh: where to store the file handle fragment
1403 * @max_len: maximum length to store there (in 4 byte units)
1404 * @parent: parent directory inode, if wanted
1405 *
1406 * This generic encode_fh function assumes that the 32 inode number
1407 * is suitable for locating an inode, and that the generation number
1408 * can be used to check that it is still valid. It places them in the
1409 * filehandle fragment where export_decode_fh expects to find them.
1410 */
1411int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len,
1412 struct inode *parent)
1413{
1414 struct fid *fid = (void *)fh;
1415 int len = *max_len;
1416 int type = FILEID_INO32_GEN;
1417
1418 if (parent && (len < 4)) {
1419 *max_len = 4;
1420 return FILEID_INVALID;
1421 } else if (len < 2) {
1422 *max_len = 2;
1423 return FILEID_INVALID;
1424 }
1425
1426 len = 2;
1427 fid->i32.ino = inode->i_ino;
1428 fid->i32.gen = inode->i_generation;
1429 if (parent) {
1430 fid->i32.parent_ino = parent->i_ino;
1431 fid->i32.parent_gen = parent->i_generation;
1432 len = 4;
1433 type = FILEID_INO32_GEN_PARENT;
1434 }
1435 *max_len = len;
1436 return type;
1437}
1438EXPORT_SYMBOL_GPL(generic_encode_ino32_fh);
1439
1440/**
1441 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
1442 * @sb: filesystem to do the file handle conversion on
1443 * @fid: file handle to convert
1444 * @fh_len: length of the file handle in bytes
1445 * @fh_type: type of file handle
1446 * @get_inode: filesystem callback to retrieve inode
1447 *
1448 * This function decodes @fid as long as it has one of the well-known
1449 * Linux filehandle types and calls @get_inode on it to retrieve the
1450 * inode for the object specified in the file handle.
1451 */
1452struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
1453 int fh_len, int fh_type, struct inode *(*get_inode)
1454 (struct super_block *sb, u64 ino, u32 gen))
1455{
1456 struct inode *inode = NULL;
1457
1458 if (fh_len < 2)
1459 return NULL;
1460
1461 switch (fh_type) {
1462 case FILEID_INO32_GEN:
1463 case FILEID_INO32_GEN_PARENT:
1464 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
1465 break;
1466 }
1467
1468 return d_obtain_alias(inode);
1469}
1470EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
1471
1472/**
1473 * generic_fh_to_parent - generic helper for the fh_to_parent export operation
1474 * @sb: filesystem to do the file handle conversion on
1475 * @fid: file handle to convert
1476 * @fh_len: length of the file handle in bytes
1477 * @fh_type: type of file handle
1478 * @get_inode: filesystem callback to retrieve inode
1479 *
1480 * This function decodes @fid as long as it has one of the well-known
1481 * Linux filehandle types and calls @get_inode on it to retrieve the
1482 * inode for the _parent_ object specified in the file handle if it
1483 * is specified in the file handle, or NULL otherwise.
1484 */
1485struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
1486 int fh_len, int fh_type, struct inode *(*get_inode)
1487 (struct super_block *sb, u64 ino, u32 gen))
1488{
1489 struct inode *inode = NULL;
1490
1491 if (fh_len <= 2)
1492 return NULL;
1493
1494 switch (fh_type) {
1495 case FILEID_INO32_GEN_PARENT:
1496 inode = get_inode(sb, fid->i32.parent_ino,
1497 (fh_len > 3 ? fid->i32.parent_gen : 0));
1498 break;
1499 }
1500
1501 return d_obtain_alias(inode);
1502}
1503EXPORT_SYMBOL_GPL(generic_fh_to_parent);
1504
1505/**
1506 * __generic_file_fsync - generic fsync implementation for simple filesystems
1507 *
1508 * @file: file to synchronize
1509 * @start: start offset in bytes
1510 * @end: end offset in bytes (inclusive)
1511 * @datasync: only synchronize essential metadata if true
1512 *
1513 * This is a generic implementation of the fsync method for simple
1514 * filesystems which track all non-inode metadata in the buffers list
1515 * hanging off the address_space structure.
1516 */
1517int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
1518 int datasync)
1519{
1520 struct inode *inode = file->f_mapping->host;
1521 int err;
1522 int ret;
1523
1524 err = file_write_and_wait_range(file, start, end);
1525 if (err)
1526 return err;
1527
1528 inode_lock(inode);
1529 ret = sync_mapping_buffers(inode->i_mapping);
1530 if (!(inode->i_state & I_DIRTY_ALL))
1531 goto out;
1532 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
1533 goto out;
1534
1535 err = sync_inode_metadata(inode, 1);
1536 if (ret == 0)
1537 ret = err;
1538
1539out:
1540 inode_unlock(inode);
1541 /* check and advance again to catch errors after syncing out buffers */
1542 err = file_check_and_advance_wb_err(file);
1543 if (ret == 0)
1544 ret = err;
1545 return ret;
1546}
1547EXPORT_SYMBOL(__generic_file_fsync);
1548
1549/**
1550 * generic_file_fsync - generic fsync implementation for simple filesystems
1551 * with flush
1552 * @file: file to synchronize
1553 * @start: start offset in bytes
1554 * @end: end offset in bytes (inclusive)
1555 * @datasync: only synchronize essential metadata if true
1556 *
1557 */
1558
1559int generic_file_fsync(struct file *file, loff_t start, loff_t end,
1560 int datasync)
1561{
1562 struct inode *inode = file->f_mapping->host;
1563 int err;
1564
1565 err = __generic_file_fsync(file, start, end, datasync);
1566 if (err)
1567 return err;
1568 return blkdev_issue_flush(inode->i_sb->s_bdev);
1569}
1570EXPORT_SYMBOL(generic_file_fsync);
1571
1572/**
1573 * generic_check_addressable - Check addressability of file system
1574 * @blocksize_bits: log of file system block size
1575 * @num_blocks: number of blocks in file system
1576 *
1577 * Determine whether a file system with @num_blocks blocks (and a
1578 * block size of 2**@blocksize_bits) is addressable by the sector_t
1579 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
1580 */
1581int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
1582{
1583 u64 last_fs_block = num_blocks - 1;
1584 u64 last_fs_page =
1585 last_fs_block >> (PAGE_SHIFT - blocksize_bits);
1586
1587 if (unlikely(num_blocks == 0))
1588 return 0;
1589
1590 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
1591 return -EINVAL;
1592
1593 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
1594 (last_fs_page > (pgoff_t)(~0ULL))) {
1595 return -EFBIG;
1596 }
1597 return 0;
1598}
1599EXPORT_SYMBOL(generic_check_addressable);
1600
1601/*
1602 * No-op implementation of ->fsync for in-memory filesystems.
1603 */
1604int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1605{
1606 return 0;
1607}
1608EXPORT_SYMBOL(noop_fsync);
1609
1610ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
1611{
1612 /*
1613 * iomap based filesystems support direct I/O without need for
1614 * this callback. However, it still needs to be set in
1615 * inode->a_ops so that open/fcntl know that direct I/O is
1616 * generally supported.
1617 */
1618 return -EINVAL;
1619}
1620EXPORT_SYMBOL_GPL(noop_direct_IO);
1621
1622/* Because kfree isn't assignment-compatible with void(void*) ;-/ */
1623void kfree_link(void *p)
1624{
1625 kfree(p);
1626}
1627EXPORT_SYMBOL(kfree_link);
1628
1629struct inode *alloc_anon_inode(struct super_block *s)
1630{
1631 static const struct address_space_operations anon_aops = {
1632 .dirty_folio = noop_dirty_folio,
1633 };
1634 struct inode *inode = new_inode_pseudo(s);
1635
1636 if (!inode)
1637 return ERR_PTR(-ENOMEM);
1638
1639 inode->i_ino = get_next_ino();
1640 inode->i_mapping->a_ops = &anon_aops;
1641
1642 /*
1643 * Mark the inode dirty from the very beginning,
1644 * that way it will never be moved to the dirty
1645 * list because mark_inode_dirty() will think
1646 * that it already _is_ on the dirty list.
1647 */
1648 inode->i_state = I_DIRTY;
1649 inode->i_mode = S_IRUSR | S_IWUSR;
1650 inode->i_uid = current_fsuid();
1651 inode->i_gid = current_fsgid();
1652 inode->i_flags |= S_PRIVATE;
1653 simple_inode_init_ts(inode);
1654 return inode;
1655}
1656EXPORT_SYMBOL(alloc_anon_inode);
1657
1658/**
1659 * simple_nosetlease - generic helper for prohibiting leases
1660 * @filp: file pointer
1661 * @arg: type of lease to obtain
1662 * @flp: new lease supplied for insertion
1663 * @priv: private data for lm_setup operation
1664 *
1665 * Generic helper for filesystems that do not wish to allow leases to be set.
1666 * All arguments are ignored and it just returns -EINVAL.
1667 */
1668int
1669simple_nosetlease(struct file *filp, int arg, struct file_lease **flp,
1670 void **priv)
1671{
1672 return -EINVAL;
1673}
1674EXPORT_SYMBOL(simple_nosetlease);
1675
1676/**
1677 * simple_get_link - generic helper to get the target of "fast" symlinks
1678 * @dentry: not used here
1679 * @inode: the symlink inode
1680 * @done: not used here
1681 *
1682 * Generic helper for filesystems to use for symlink inodes where a pointer to
1683 * the symlink target is stored in ->i_link. NOTE: this isn't normally called,
1684 * since as an optimization the path lookup code uses any non-NULL ->i_link
1685 * directly, without calling ->get_link(). But ->get_link() still must be set,
1686 * to mark the inode_operations as being for a symlink.
1687 *
1688 * Return: the symlink target
1689 */
1690const char *simple_get_link(struct dentry *dentry, struct inode *inode,
1691 struct delayed_call *done)
1692{
1693 return inode->i_link;
1694}
1695EXPORT_SYMBOL(simple_get_link);
1696
1697const struct inode_operations simple_symlink_inode_operations = {
1698 .get_link = simple_get_link,
1699};
1700EXPORT_SYMBOL(simple_symlink_inode_operations);
1701
1702/*
1703 * Operations for a permanently empty directory.
1704 */
1705static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
1706{
1707 return ERR_PTR(-ENOENT);
1708}
1709
1710static int empty_dir_setattr(struct mnt_idmap *idmap,
1711 struct dentry *dentry, struct iattr *attr)
1712{
1713 return -EPERM;
1714}
1715
1716static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
1717{
1718 return -EOPNOTSUPP;
1719}
1720
1721static const struct inode_operations empty_dir_inode_operations = {
1722 .lookup = empty_dir_lookup,
1723 .setattr = empty_dir_setattr,
1724 .listxattr = empty_dir_listxattr,
1725};
1726
1727static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
1728{
1729 /* An empty directory has two entries . and .. at offsets 0 and 1 */
1730 return generic_file_llseek_size(file, offset, whence, 2, 2);
1731}
1732
1733static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
1734{
1735 dir_emit_dots(file, ctx);
1736 return 0;
1737}
1738
1739static const struct file_operations empty_dir_operations = {
1740 .llseek = empty_dir_llseek,
1741 .read = generic_read_dir,
1742 .iterate_shared = empty_dir_readdir,
1743 .fsync = noop_fsync,
1744};
1745
1746
1747void make_empty_dir_inode(struct inode *inode)
1748{
1749 set_nlink(inode, 2);
1750 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
1751 inode->i_uid = GLOBAL_ROOT_UID;
1752 inode->i_gid = GLOBAL_ROOT_GID;
1753 inode->i_rdev = 0;
1754 inode->i_size = 0;
1755 inode->i_blkbits = PAGE_SHIFT;
1756 inode->i_blocks = 0;
1757
1758 inode->i_op = &empty_dir_inode_operations;
1759 inode->i_opflags &= ~IOP_XATTR;
1760 inode->i_fop = &empty_dir_operations;
1761}
1762
1763bool is_empty_dir_inode(struct inode *inode)
1764{
1765 return (inode->i_fop == &empty_dir_operations) &&
1766 (inode->i_op == &empty_dir_inode_operations);
1767}
1768
1769#if IS_ENABLED(CONFIG_UNICODE)
1770/**
1771 * generic_ci_d_compare - generic d_compare implementation for casefolding filesystems
1772 * @dentry: dentry whose name we are checking against
1773 * @len: len of name of dentry
1774 * @str: str pointer to name of dentry
1775 * @name: Name to compare against
1776 *
1777 * Return: 0 if names match, 1 if mismatch, or -ERRNO
1778 */
1779int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
1780 const char *str, const struct qstr *name)
1781{
1782 const struct dentry *parent;
1783 const struct inode *dir;
1784 char strbuf[DNAME_INLINE_LEN];
1785 struct qstr qstr;
1786
1787 /*
1788 * Attempt a case-sensitive match first. It is cheaper and
1789 * should cover most lookups, including all the sane
1790 * applications that expect a case-sensitive filesystem.
1791 *
1792 * This comparison is safe under RCU because the caller
1793 * guarantees the consistency between str and len. See
1794 * __d_lookup_rcu_op_compare() for details.
1795 */
1796 if (len == name->len && !memcmp(str, name->name, len))
1797 return 0;
1798
1799 parent = READ_ONCE(dentry->d_parent);
1800 dir = READ_ONCE(parent->d_inode);
1801 if (!dir || !IS_CASEFOLDED(dir))
1802 return 1;
1803
1804 /*
1805 * If the dentry name is stored in-line, then it may be concurrently
1806 * modified by a rename. If this happens, the VFS will eventually retry
1807 * the lookup, so it doesn't matter what ->d_compare() returns.
1808 * However, it's unsafe to call utf8_strncasecmp() with an unstable
1809 * string. Therefore, we have to copy the name into a temporary buffer.
1810 */
1811 if (len <= DNAME_INLINE_LEN - 1) {
1812 memcpy(strbuf, str, len);
1813 strbuf[len] = 0;
1814 str = strbuf;
1815 /* prevent compiler from optimizing out the temporary buffer */
1816 barrier();
1817 }
1818 qstr.len = len;
1819 qstr.name = str;
1820
1821 return utf8_strncasecmp(dentry->d_sb->s_encoding, name, &qstr);
1822}
1823EXPORT_SYMBOL(generic_ci_d_compare);
1824
1825/**
1826 * generic_ci_d_hash - generic d_hash implementation for casefolding filesystems
1827 * @dentry: dentry of the parent directory
1828 * @str: qstr of name whose hash we should fill in
1829 *
1830 * Return: 0 if hash was successful or unchanged, and -EINVAL on error
1831 */
1832int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
1833{
1834 const struct inode *dir = READ_ONCE(dentry->d_inode);
1835 struct super_block *sb = dentry->d_sb;
1836 const struct unicode_map *um = sb->s_encoding;
1837 int ret;
1838
1839 if (!dir || !IS_CASEFOLDED(dir))
1840 return 0;
1841
1842 ret = utf8_casefold_hash(um, dentry, str);
1843 if (ret < 0 && sb_has_strict_encoding(sb))
1844 return -EINVAL;
1845 return 0;
1846}
1847EXPORT_SYMBOL(generic_ci_d_hash);
1848
1849static const struct dentry_operations generic_ci_dentry_ops = {
1850 .d_hash = generic_ci_d_hash,
1851 .d_compare = generic_ci_d_compare,
1852#ifdef CONFIG_FS_ENCRYPTION
1853 .d_revalidate = fscrypt_d_revalidate,
1854#endif
1855};
1856
1857/**
1858 * generic_ci_match() - Match a name (case-insensitively) with a dirent.
1859 * This is a filesystem helper for comparison with directory entries.
1860 * generic_ci_d_compare should be used in VFS' ->d_compare instead.
1861 *
1862 * @parent: Inode of the parent of the dirent under comparison
1863 * @name: name under lookup.
1864 * @folded_name: Optional pre-folded name under lookup
1865 * @de_name: Dirent name.
1866 * @de_name_len: dirent name length.
1867 *
1868 * Test whether a case-insensitive directory entry matches the filename
1869 * being searched. If @folded_name is provided, it is used instead of
1870 * recalculating the casefold of @name.
1871 *
1872 * Return: > 0 if the directory entry matches, 0 if it doesn't match, or
1873 * < 0 on error.
1874 */
1875int generic_ci_match(const struct inode *parent,
1876 const struct qstr *name,
1877 const struct qstr *folded_name,
1878 const u8 *de_name, u32 de_name_len)
1879{
1880 const struct super_block *sb = parent->i_sb;
1881 const struct unicode_map *um = sb->s_encoding;
1882 struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len);
1883 struct qstr dirent = QSTR_INIT(de_name, de_name_len);
1884 int res = 0;
1885
1886 if (IS_ENCRYPTED(parent)) {
1887 const struct fscrypt_str encrypted_name =
1888 FSTR_INIT((u8 *) de_name, de_name_len);
1889
1890 if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent)))
1891 return -EINVAL;
1892
1893 decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL);
1894 if (!decrypted_name.name)
1895 return -ENOMEM;
1896 res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name,
1897 &decrypted_name);
1898 if (res < 0) {
1899 kfree(decrypted_name.name);
1900 return res;
1901 }
1902 dirent.name = decrypted_name.name;
1903 dirent.len = decrypted_name.len;
1904 }
1905
1906 /*
1907 * Attempt a case-sensitive match first. It is cheaper and
1908 * should cover most lookups, including all the sane
1909 * applications that expect a case-sensitive filesystem.
1910 */
1911
1912 if (dirent.len == name->len &&
1913 !memcmp(name->name, dirent.name, dirent.len))
1914 goto out;
1915
1916 if (folded_name->name)
1917 res = utf8_strncasecmp_folded(um, folded_name, &dirent);
1918 else
1919 res = utf8_strncasecmp(um, name, &dirent);
1920
1921out:
1922 kfree(decrypted_name.name);
1923 if (res < 0 && sb_has_strict_encoding(sb)) {
1924 pr_err_ratelimited("Directory contains filename that is invalid UTF-8");
1925 return 0;
1926 }
1927 return !res;
1928}
1929EXPORT_SYMBOL(generic_ci_match);
1930#endif
1931
1932#ifdef CONFIG_FS_ENCRYPTION
1933static const struct dentry_operations generic_encrypted_dentry_ops = {
1934 .d_revalidate = fscrypt_d_revalidate,
1935};
1936#endif
1937
1938/**
1939 * generic_set_sb_d_ops - helper for choosing the set of
1940 * filesystem-wide dentry operations for the enabled features
1941 * @sb: superblock to be configured
1942 *
1943 * Filesystems supporting casefolding and/or fscrypt can call this
1944 * helper at mount-time to configure sb->s_d_op to best set of dentry
1945 * operations required for the enabled features. The helper must be
1946 * called after these have been configured, but before the root dentry
1947 * is created.
1948 */
1949void generic_set_sb_d_ops(struct super_block *sb)
1950{
1951#if IS_ENABLED(CONFIG_UNICODE)
1952 if (sb->s_encoding) {
1953 sb->s_d_op = &generic_ci_dentry_ops;
1954 return;
1955 }
1956#endif
1957#ifdef CONFIG_FS_ENCRYPTION
1958 if (sb->s_cop) {
1959 sb->s_d_op = &generic_encrypted_dentry_ops;
1960 return;
1961 }
1962#endif
1963}
1964EXPORT_SYMBOL(generic_set_sb_d_ops);
1965
1966/**
1967 * inode_maybe_inc_iversion - increments i_version
1968 * @inode: inode with the i_version that should be updated
1969 * @force: increment the counter even if it's not necessary?
1970 *
1971 * Every time the inode is modified, the i_version field must be seen to have
1972 * changed by any observer.
1973 *
1974 * If "force" is set or the QUERIED flag is set, then ensure that we increment
1975 * the value, and clear the queried flag.
1976 *
1977 * In the common case where neither is set, then we can return "false" without
1978 * updating i_version.
1979 *
1980 * If this function returns false, and no other metadata has changed, then we
1981 * can avoid logging the metadata.
1982 */
1983bool inode_maybe_inc_iversion(struct inode *inode, bool force)
1984{
1985 u64 cur, new;
1986
1987 /*
1988 * The i_version field is not strictly ordered with any other inode
1989 * information, but the legacy inode_inc_iversion code used a spinlock
1990 * to serialize increments.
1991 *
1992 * We add a full memory barrier to ensure that any de facto ordering
1993 * with other state is preserved (either implicitly coming from cmpxchg
1994 * or explicitly from smp_mb if we don't know upfront if we will execute
1995 * the former).
1996 *
1997 * These barriers pair with inode_query_iversion().
1998 */
1999 cur = inode_peek_iversion_raw(inode);
2000 if (!force && !(cur & I_VERSION_QUERIED)) {
2001 smp_mb();
2002 cur = inode_peek_iversion_raw(inode);
2003 }
2004
2005 do {
2006 /* If flag is clear then we needn't do anything */
2007 if (!force && !(cur & I_VERSION_QUERIED))
2008 return false;
2009
2010 /* Since lowest bit is flag, add 2 to avoid it */
2011 new = (cur & ~I_VERSION_QUERIED) + I_VERSION_INCREMENT;
2012 } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new));
2013 return true;
2014}
2015EXPORT_SYMBOL(inode_maybe_inc_iversion);
2016
2017/**
2018 * inode_query_iversion - read i_version for later use
2019 * @inode: inode from which i_version should be read
2020 *
2021 * Read the inode i_version counter. This should be used by callers that wish
2022 * to store the returned i_version for later comparison. This will guarantee
2023 * that a later query of the i_version will result in a different value if
2024 * anything has changed.
2025 *
2026 * In this implementation, we fetch the current value, set the QUERIED flag and
2027 * then try to swap it into place with a cmpxchg, if it wasn't already set. If
2028 * that fails, we try again with the newly fetched value from the cmpxchg.
2029 */
2030u64 inode_query_iversion(struct inode *inode)
2031{
2032 u64 cur, new;
2033 bool fenced = false;
2034
2035 /*
2036 * Memory barriers (implicit in cmpxchg, explicit in smp_mb) pair with
2037 * inode_maybe_inc_iversion(), see that routine for more details.
2038 */
2039 cur = inode_peek_iversion_raw(inode);
2040 do {
2041 /* If flag is already set, then no need to swap */
2042 if (cur & I_VERSION_QUERIED) {
2043 if (!fenced)
2044 smp_mb();
2045 break;
2046 }
2047
2048 fenced = true;
2049 new = cur | I_VERSION_QUERIED;
2050 } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new));
2051 return cur >> I_VERSION_QUERIED_SHIFT;
2052}
2053EXPORT_SYMBOL(inode_query_iversion);
2054
2055ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter,
2056 ssize_t direct_written, ssize_t buffered_written)
2057{
2058 struct address_space *mapping = iocb->ki_filp->f_mapping;
2059 loff_t pos = iocb->ki_pos - buffered_written;
2060 loff_t end = iocb->ki_pos - 1;
2061 int err;
2062
2063 /*
2064 * If the buffered write fallback returned an error, we want to return
2065 * the number of bytes which were written by direct I/O, or the error
2066 * code if that was zero.
2067 *
2068 * Note that this differs from normal direct-io semantics, which will
2069 * return -EFOO even if some bytes were written.
2070 */
2071 if (unlikely(buffered_written < 0)) {
2072 if (direct_written)
2073 return direct_written;
2074 return buffered_written;
2075 }
2076
2077 /*
2078 * We need to ensure that the page cache pages are written to disk and
2079 * invalidated to preserve the expected O_DIRECT semantics.
2080 */
2081 err = filemap_write_and_wait_range(mapping, pos, end);
2082 if (err < 0) {
2083 /*
2084 * We don't know how much we wrote, so just return the number of
2085 * bytes which were direct-written
2086 */
2087 iocb->ki_pos -= buffered_written;
2088 if (direct_written)
2089 return direct_written;
2090 return err;
2091 }
2092 invalidate_mapping_pages(mapping, pos >> PAGE_SHIFT, end >> PAGE_SHIFT);
2093 return direct_written + buffered_written;
2094}
2095EXPORT_SYMBOL_GPL(direct_write_fallback);
2096
2097/**
2098 * simple_inode_init_ts - initialize the timestamps for a new inode
2099 * @inode: inode to be initialized
2100 *
2101 * When a new inode is created, most filesystems set the timestamps to the
2102 * current time. Add a helper to do this.
2103 */
2104struct timespec64 simple_inode_init_ts(struct inode *inode)
2105{
2106 struct timespec64 ts = inode_set_ctime_current(inode);
2107
2108 inode_set_atime_to_ts(inode, ts);
2109 inode_set_mtime_to_ts(inode, ts);
2110 return ts;
2111}
2112EXPORT_SYMBOL(simple_inode_init_ts);
2113
2114static inline struct dentry *get_stashed_dentry(struct dentry **stashed)
2115{
2116 struct dentry *dentry;
2117
2118 guard(rcu)();
2119 dentry = rcu_dereference(*stashed);
2120 if (!dentry)
2121 return NULL;
2122 if (!lockref_get_not_dead(&dentry->d_lockref))
2123 return NULL;
2124 return dentry;
2125}
2126
2127static struct dentry *prepare_anon_dentry(struct dentry **stashed,
2128 struct super_block *sb,
2129 void *data)
2130{
2131 struct dentry *dentry;
2132 struct inode *inode;
2133 const struct stashed_operations *sops = sb->s_fs_info;
2134 int ret;
2135
2136 inode = new_inode_pseudo(sb);
2137 if (!inode) {
2138 sops->put_data(data);
2139 return ERR_PTR(-ENOMEM);
2140 }
2141
2142 inode->i_flags |= S_IMMUTABLE;
2143 inode->i_mode = S_IFREG;
2144 simple_inode_init_ts(inode);
2145
2146 ret = sops->init_inode(inode, data);
2147 if (ret < 0) {
2148 iput(inode);
2149 return ERR_PTR(ret);
2150 }
2151
2152 /* Notice when this is changed. */
2153 WARN_ON_ONCE(!S_ISREG(inode->i_mode));
2154 WARN_ON_ONCE(!IS_IMMUTABLE(inode));
2155
2156 dentry = d_alloc_anon(sb);
2157 if (!dentry) {
2158 iput(inode);
2159 return ERR_PTR(-ENOMEM);
2160 }
2161
2162 /* Store address of location where dentry's supposed to be stashed. */
2163 dentry->d_fsdata = stashed;
2164
2165 /* @data is now owned by the fs */
2166 d_instantiate(dentry, inode);
2167 return dentry;
2168}
2169
2170static struct dentry *stash_dentry(struct dentry **stashed,
2171 struct dentry *dentry)
2172{
2173 guard(rcu)();
2174 for (;;) {
2175 struct dentry *old;
2176
2177 /* Assume any old dentry was cleared out. */
2178 old = cmpxchg(stashed, NULL, dentry);
2179 if (likely(!old))
2180 return dentry;
2181
2182 /* Check if somebody else installed a reusable dentry. */
2183 if (lockref_get_not_dead(&old->d_lockref))
2184 return old;
2185
2186 /* There's an old dead dentry there, try to take it over. */
2187 if (likely(try_cmpxchg(stashed, &old, dentry)))
2188 return dentry;
2189 }
2190}
2191
2192/**
2193 * path_from_stashed - create path from stashed or new dentry
2194 * @stashed: where to retrieve or stash dentry
2195 * @mnt: mnt of the filesystems to use
2196 * @data: data to store in inode->i_private
2197 * @path: path to create
2198 *
2199 * The function tries to retrieve a stashed dentry from @stashed. If the dentry
2200 * is still valid then it will be reused. If the dentry isn't able the function
2201 * will allocate a new dentry and inode. It will then check again whether it
2202 * can reuse an existing dentry in case one has been added in the meantime or
2203 * update @stashed with the newly added dentry.
2204 *
2205 * Special-purpose helper for nsfs and pidfs.
2206 *
2207 * Return: On success zero and on failure a negative error is returned.
2208 */
2209int path_from_stashed(struct dentry **stashed, struct vfsmount *mnt, void *data,
2210 struct path *path)
2211{
2212 struct dentry *dentry;
2213 const struct stashed_operations *sops = mnt->mnt_sb->s_fs_info;
2214
2215 /* See if dentry can be reused. */
2216 path->dentry = get_stashed_dentry(stashed);
2217 if (path->dentry) {
2218 sops->put_data(data);
2219 goto out_path;
2220 }
2221
2222 /* Allocate a new dentry. */
2223 dentry = prepare_anon_dentry(stashed, mnt->mnt_sb, data);
2224 if (IS_ERR(dentry))
2225 return PTR_ERR(dentry);
2226
2227 /* Added a new dentry. @data is now owned by the filesystem. */
2228 path->dentry = stash_dentry(stashed, dentry);
2229 if (path->dentry != dentry)
2230 dput(dentry);
2231
2232out_path:
2233 WARN_ON_ONCE(path->dentry->d_fsdata != stashed);
2234 WARN_ON_ONCE(d_inode(path->dentry)->i_private != data);
2235 path->mnt = mntget(mnt);
2236 return 0;
2237}
2238
2239void stashed_dentry_prune(struct dentry *dentry)
2240{
2241 struct dentry **stashed = dentry->d_fsdata;
2242 struct inode *inode = d_inode(dentry);
2243
2244 if (WARN_ON_ONCE(!stashed))
2245 return;
2246
2247 if (!inode)
2248 return;
2249
2250 /*
2251 * Only replace our own @dentry as someone else might've
2252 * already cleared out @dentry and stashed their own
2253 * dentry in there.
2254 */
2255 cmpxchg(stashed, dentry, NULL);
2256}