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