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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/*
2 * fs/libfs.c
3 * Library for filesystems writers.
4 */
5
6#include <linux/export.h>
7#include <linux/pagemap.h>
8#include <linux/slab.h>
9#include <linux/mount.h>
10#include <linux/vfs.h>
11#include <linux/quotaops.h>
12#include <linux/mutex.h>
13#include <linux/namei.h>
14#include <linux/exportfs.h>
15#include <linux/writeback.h>
16#include <linux/buffer_head.h> /* sync_mapping_buffers */
17
18#include <asm/uaccess.h>
19
20#include "internal.h"
21
22static inline int simple_positive(struct dentry *dentry)
23{
24 return dentry->d_inode && !d_unhashed(dentry);
25}
26
27int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
28 struct kstat *stat)
29{
30 struct inode *inode = dentry->d_inode;
31 generic_fillattr(inode, stat);
32 stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_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_CACHE_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 static struct qstr cursor_name = QSTR_INIT(".", 1);
79
80 file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
81
82 return file->private_data ? 0 : -ENOMEM;
83}
84EXPORT_SYMBOL(dcache_dir_open);
85
86int dcache_dir_close(struct inode *inode, struct file *file)
87{
88 dput(file->private_data);
89 return 0;
90}
91EXPORT_SYMBOL(dcache_dir_close);
92
93loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
94{
95 struct dentry *dentry = file->f_path.dentry;
96 mutex_lock(&dentry->d_inode->i_mutex);
97 switch (whence) {
98 case 1:
99 offset += file->f_pos;
100 case 0:
101 if (offset >= 0)
102 break;
103 default:
104 mutex_unlock(&dentry->d_inode->i_mutex);
105 return -EINVAL;
106 }
107 if (offset != file->f_pos) {
108 file->f_pos = offset;
109 if (file->f_pos >= 2) {
110 struct list_head *p;
111 struct dentry *cursor = file->private_data;
112 loff_t n = file->f_pos - 2;
113
114 spin_lock(&dentry->d_lock);
115 /* d_lock not required for cursor */
116 list_del(&cursor->d_u.d_child);
117 p = dentry->d_subdirs.next;
118 while (n && p != &dentry->d_subdirs) {
119 struct dentry *next;
120 next = list_entry(p, struct dentry, d_u.d_child);
121 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
122 if (simple_positive(next))
123 n--;
124 spin_unlock(&next->d_lock);
125 p = p->next;
126 }
127 list_add_tail(&cursor->d_u.d_child, p);
128 spin_unlock(&dentry->d_lock);
129 }
130 }
131 mutex_unlock(&dentry->d_inode->i_mutex);
132 return offset;
133}
134EXPORT_SYMBOL(dcache_dir_lseek);
135
136/* Relationship between i_mode and the DT_xxx types */
137static inline unsigned char dt_type(struct inode *inode)
138{
139 return (inode->i_mode >> 12) & 15;
140}
141
142/*
143 * Directory is locked and all positive dentries in it are safe, since
144 * for ramfs-type trees they can't go away without unlink() or rmdir(),
145 * both impossible due to the lock on directory.
146 */
147
148int dcache_readdir(struct file *file, struct dir_context *ctx)
149{
150 struct dentry *dentry = file->f_path.dentry;
151 struct dentry *cursor = file->private_data;
152 struct list_head *p, *q = &cursor->d_u.d_child;
153
154 if (!dir_emit_dots(file, ctx))
155 return 0;
156 spin_lock(&dentry->d_lock);
157 if (ctx->pos == 2)
158 list_move(q, &dentry->d_subdirs);
159
160 for (p = q->next; p != &dentry->d_subdirs; p = p->next) {
161 struct dentry *next = list_entry(p, struct dentry, d_u.d_child);
162 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
163 if (!simple_positive(next)) {
164 spin_unlock(&next->d_lock);
165 continue;
166 }
167
168 spin_unlock(&next->d_lock);
169 spin_unlock(&dentry->d_lock);
170 if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
171 next->d_inode->i_ino, dt_type(next->d_inode)))
172 return 0;
173 spin_lock(&dentry->d_lock);
174 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
175 /* next is still alive */
176 list_move(q, p);
177 spin_unlock(&next->d_lock);
178 p = q;
179 ctx->pos++;
180 }
181 spin_unlock(&dentry->d_lock);
182 return 0;
183}
184EXPORT_SYMBOL(dcache_readdir);
185
186ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
187{
188 return -EISDIR;
189}
190EXPORT_SYMBOL(generic_read_dir);
191
192const struct file_operations simple_dir_operations = {
193 .open = dcache_dir_open,
194 .release = dcache_dir_close,
195 .llseek = dcache_dir_lseek,
196 .read = generic_read_dir,
197 .iterate = dcache_readdir,
198 .fsync = noop_fsync,
199};
200EXPORT_SYMBOL(simple_dir_operations);
201
202const struct inode_operations simple_dir_inode_operations = {
203 .lookup = simple_lookup,
204};
205EXPORT_SYMBOL(simple_dir_inode_operations);
206
207static const struct super_operations simple_super_operations = {
208 .statfs = simple_statfs,
209};
210
211/*
212 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
213 * will never be mountable)
214 */
215struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name,
216 const struct super_operations *ops,
217 const struct dentry_operations *dops, unsigned long magic)
218{
219 struct super_block *s;
220 struct dentry *dentry;
221 struct inode *root;
222 struct qstr d_name = QSTR_INIT(name, strlen(name));
223
224 s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL);
225 if (IS_ERR(s))
226 return ERR_CAST(s);
227
228 s->s_maxbytes = MAX_LFS_FILESIZE;
229 s->s_blocksize = PAGE_SIZE;
230 s->s_blocksize_bits = PAGE_SHIFT;
231 s->s_magic = magic;
232 s->s_op = ops ? ops : &simple_super_operations;
233 s->s_time_gran = 1;
234 root = new_inode(s);
235 if (!root)
236 goto Enomem;
237 /*
238 * since this is the first inode, make it number 1. New inodes created
239 * after this must take care not to collide with it (by passing
240 * max_reserved of 1 to iunique).
241 */
242 root->i_ino = 1;
243 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
244 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
245 dentry = __d_alloc(s, &d_name);
246 if (!dentry) {
247 iput(root);
248 goto Enomem;
249 }
250 d_instantiate(dentry, root);
251 s->s_root = dentry;
252 s->s_d_op = dops;
253 s->s_flags |= MS_ACTIVE;
254 return dget(s->s_root);
255
256Enomem:
257 deactivate_locked_super(s);
258 return ERR_PTR(-ENOMEM);
259}
260EXPORT_SYMBOL(mount_pseudo);
261
262int simple_open(struct inode *inode, struct file *file)
263{
264 if (inode->i_private)
265 file->private_data = inode->i_private;
266 return 0;
267}
268EXPORT_SYMBOL(simple_open);
269
270int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
271{
272 struct inode *inode = old_dentry->d_inode;
273
274 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
275 inc_nlink(inode);
276 ihold(inode);
277 dget(dentry);
278 d_instantiate(dentry, inode);
279 return 0;
280}
281EXPORT_SYMBOL(simple_link);
282
283int simple_empty(struct dentry *dentry)
284{
285 struct dentry *child;
286 int ret = 0;
287
288 spin_lock(&dentry->d_lock);
289 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) {
290 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
291 if (simple_positive(child)) {
292 spin_unlock(&child->d_lock);
293 goto out;
294 }
295 spin_unlock(&child->d_lock);
296 }
297 ret = 1;
298out:
299 spin_unlock(&dentry->d_lock);
300 return ret;
301}
302EXPORT_SYMBOL(simple_empty);
303
304int simple_unlink(struct inode *dir, struct dentry *dentry)
305{
306 struct inode *inode = dentry->d_inode;
307
308 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
309 drop_nlink(inode);
310 dput(dentry);
311 return 0;
312}
313EXPORT_SYMBOL(simple_unlink);
314
315int simple_rmdir(struct inode *dir, struct dentry *dentry)
316{
317 if (!simple_empty(dentry))
318 return -ENOTEMPTY;
319
320 drop_nlink(dentry->d_inode);
321 simple_unlink(dir, dentry);
322 drop_nlink(dir);
323 return 0;
324}
325EXPORT_SYMBOL(simple_rmdir);
326
327int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
328 struct inode *new_dir, struct dentry *new_dentry)
329{
330 struct inode *inode = old_dentry->d_inode;
331 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
332
333 if (!simple_empty(new_dentry))
334 return -ENOTEMPTY;
335
336 if (new_dentry->d_inode) {
337 simple_unlink(new_dir, new_dentry);
338 if (they_are_dirs) {
339 drop_nlink(new_dentry->d_inode);
340 drop_nlink(old_dir);
341 }
342 } else if (they_are_dirs) {
343 drop_nlink(old_dir);
344 inc_nlink(new_dir);
345 }
346
347 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
348 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
349
350 return 0;
351}
352EXPORT_SYMBOL(simple_rename);
353
354/**
355 * simple_setattr - setattr for simple filesystem
356 * @dentry: dentry
357 * @iattr: iattr structure
358 *
359 * Returns 0 on success, -error on failure.
360 *
361 * simple_setattr is a simple ->setattr implementation without a proper
362 * implementation of size changes.
363 *
364 * It can either be used for in-memory filesystems or special files
365 * on simple regular filesystems. Anything that needs to change on-disk
366 * or wire state on size changes needs its own setattr method.
367 */
368int simple_setattr(struct dentry *dentry, struct iattr *iattr)
369{
370 struct inode *inode = dentry->d_inode;
371 int error;
372
373 error = inode_change_ok(inode, iattr);
374 if (error)
375 return error;
376
377 if (iattr->ia_valid & ATTR_SIZE)
378 truncate_setsize(inode, iattr->ia_size);
379 setattr_copy(inode, iattr);
380 mark_inode_dirty(inode);
381 return 0;
382}
383EXPORT_SYMBOL(simple_setattr);
384
385int simple_readpage(struct file *file, struct page *page)
386{
387 clear_highpage(page);
388 flush_dcache_page(page);
389 SetPageUptodate(page);
390 unlock_page(page);
391 return 0;
392}
393EXPORT_SYMBOL(simple_readpage);
394
395int simple_write_begin(struct file *file, struct address_space *mapping,
396 loff_t pos, unsigned len, unsigned flags,
397 struct page **pagep, void **fsdata)
398{
399 struct page *page;
400 pgoff_t index;
401
402 index = pos >> PAGE_CACHE_SHIFT;
403
404 page = grab_cache_page_write_begin(mapping, index, flags);
405 if (!page)
406 return -ENOMEM;
407
408 *pagep = page;
409
410 if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) {
411 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
412
413 zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE);
414 }
415 return 0;
416}
417EXPORT_SYMBOL(simple_write_begin);
418
419/**
420 * simple_write_end - .write_end helper for non-block-device FSes
421 * @available: See .write_end of address_space_operations
422 * @file: "
423 * @mapping: "
424 * @pos: "
425 * @len: "
426 * @copied: "
427 * @page: "
428 * @fsdata: "
429 *
430 * simple_write_end does the minimum needed for updating a page after writing is
431 * done. It has the same API signature as the .write_end of
432 * address_space_operations vector. So it can just be set onto .write_end for
433 * FSes that don't need any other processing. i_mutex is assumed to be held.
434 * Block based filesystems should use generic_write_end().
435 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
436 * is not called, so a filesystem that actually does store data in .write_inode
437 * should extend on what's done here with a call to mark_inode_dirty() in the
438 * case that i_size has changed.
439 */
440int simple_write_end(struct file *file, struct address_space *mapping,
441 loff_t pos, unsigned len, unsigned copied,
442 struct page *page, void *fsdata)
443{
444 struct inode *inode = page->mapping->host;
445 loff_t last_pos = pos + copied;
446
447 /* zero the stale part of the page if we did a short copy */
448 if (copied < len) {
449 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
450
451 zero_user(page, from + copied, len - copied);
452 }
453
454 if (!PageUptodate(page))
455 SetPageUptodate(page);
456 /*
457 * No need to use i_size_read() here, the i_size
458 * cannot change under us because we hold the i_mutex.
459 */
460 if (last_pos > inode->i_size)
461 i_size_write(inode, last_pos);
462
463 set_page_dirty(page);
464 unlock_page(page);
465 page_cache_release(page);
466
467 return copied;
468}
469EXPORT_SYMBOL(simple_write_end);
470
471/*
472 * the inodes created here are not hashed. If you use iunique to generate
473 * unique inode values later for this filesystem, then you must take care
474 * to pass it an appropriate max_reserved value to avoid collisions.
475 */
476int simple_fill_super(struct super_block *s, unsigned long magic,
477 struct tree_descr *files)
478{
479 struct inode *inode;
480 struct dentry *root;
481 struct dentry *dentry;
482 int i;
483
484 s->s_blocksize = PAGE_CACHE_SIZE;
485 s->s_blocksize_bits = PAGE_CACHE_SHIFT;
486 s->s_magic = magic;
487 s->s_op = &simple_super_operations;
488 s->s_time_gran = 1;
489
490 inode = new_inode(s);
491 if (!inode)
492 return -ENOMEM;
493 /*
494 * because the root inode is 1, the files array must not contain an
495 * entry at index 1
496 */
497 inode->i_ino = 1;
498 inode->i_mode = S_IFDIR | 0755;
499 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
500 inode->i_op = &simple_dir_inode_operations;
501 inode->i_fop = &simple_dir_operations;
502 set_nlink(inode, 2);
503 root = d_make_root(inode);
504 if (!root)
505 return -ENOMEM;
506 for (i = 0; !files->name || files->name[0]; i++, files++) {
507 if (!files->name)
508 continue;
509
510 /* warn if it tries to conflict with the root inode */
511 if (unlikely(i == 1))
512 printk(KERN_WARNING "%s: %s passed in a files array"
513 "with an index of 1!\n", __func__,
514 s->s_type->name);
515
516 dentry = d_alloc_name(root, files->name);
517 if (!dentry)
518 goto out;
519 inode = new_inode(s);
520 if (!inode) {
521 dput(dentry);
522 goto out;
523 }
524 inode->i_mode = S_IFREG | files->mode;
525 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
526 inode->i_fop = files->ops;
527 inode->i_ino = i;
528 d_add(dentry, inode);
529 }
530 s->s_root = root;
531 return 0;
532out:
533 d_genocide(root);
534 shrink_dcache_parent(root);
535 dput(root);
536 return -ENOMEM;
537}
538EXPORT_SYMBOL(simple_fill_super);
539
540static DEFINE_SPINLOCK(pin_fs_lock);
541
542int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
543{
544 struct vfsmount *mnt = NULL;
545 spin_lock(&pin_fs_lock);
546 if (unlikely(!*mount)) {
547 spin_unlock(&pin_fs_lock);
548 mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, NULL);
549 if (IS_ERR(mnt))
550 return PTR_ERR(mnt);
551 spin_lock(&pin_fs_lock);
552 if (!*mount)
553 *mount = mnt;
554 }
555 mntget(*mount);
556 ++*count;
557 spin_unlock(&pin_fs_lock);
558 mntput(mnt);
559 return 0;
560}
561EXPORT_SYMBOL(simple_pin_fs);
562
563void simple_release_fs(struct vfsmount **mount, int *count)
564{
565 struct vfsmount *mnt;
566 spin_lock(&pin_fs_lock);
567 mnt = *mount;
568 if (!--*count)
569 *mount = NULL;
570 spin_unlock(&pin_fs_lock);
571 mntput(mnt);
572}
573EXPORT_SYMBOL(simple_release_fs);
574
575/**
576 * simple_read_from_buffer - copy data from the buffer to user space
577 * @to: the user space buffer to read to
578 * @count: the maximum number of bytes to read
579 * @ppos: the current position in the buffer
580 * @from: the buffer to read from
581 * @available: the size of the buffer
582 *
583 * The simple_read_from_buffer() function reads up to @count bytes from the
584 * buffer @from at offset @ppos into the user space address starting at @to.
585 *
586 * On success, the number of bytes read is returned and the offset @ppos is
587 * advanced by this number, or negative value is returned on error.
588 **/
589ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
590 const void *from, size_t available)
591{
592 loff_t pos = *ppos;
593 size_t ret;
594
595 if (pos < 0)
596 return -EINVAL;
597 if (pos >= available || !count)
598 return 0;
599 if (count > available - pos)
600 count = available - pos;
601 ret = copy_to_user(to, from + pos, count);
602 if (ret == count)
603 return -EFAULT;
604 count -= ret;
605 *ppos = pos + count;
606 return count;
607}
608EXPORT_SYMBOL(simple_read_from_buffer);
609
610/**
611 * simple_write_to_buffer - copy data from user space to the buffer
612 * @to: the buffer to write to
613 * @available: the size of the buffer
614 * @ppos: the current position in the buffer
615 * @from: the user space buffer to read from
616 * @count: the maximum number of bytes to read
617 *
618 * The simple_write_to_buffer() function reads up to @count bytes from the user
619 * space address starting at @from into the buffer @to at offset @ppos.
620 *
621 * On success, the number of bytes written is returned and the offset @ppos is
622 * advanced by this number, or negative value is returned on error.
623 **/
624ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
625 const void __user *from, size_t count)
626{
627 loff_t pos = *ppos;
628 size_t res;
629
630 if (pos < 0)
631 return -EINVAL;
632 if (pos >= available || !count)
633 return 0;
634 if (count > available - pos)
635 count = available - pos;
636 res = copy_from_user(to + pos, from, count);
637 if (res == count)
638 return -EFAULT;
639 count -= res;
640 *ppos = pos + count;
641 return count;
642}
643EXPORT_SYMBOL(simple_write_to_buffer);
644
645/**
646 * memory_read_from_buffer - copy data from the buffer
647 * @to: the kernel space buffer to read to
648 * @count: the maximum number of bytes to read
649 * @ppos: the current position in the buffer
650 * @from: the buffer to read from
651 * @available: the size of the buffer
652 *
653 * The memory_read_from_buffer() function reads up to @count bytes from the
654 * buffer @from at offset @ppos into the kernel space address starting at @to.
655 *
656 * On success, the number of bytes read is returned and the offset @ppos is
657 * advanced by this number, or negative value is returned on error.
658 **/
659ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
660 const void *from, size_t available)
661{
662 loff_t pos = *ppos;
663
664 if (pos < 0)
665 return -EINVAL;
666 if (pos >= available)
667 return 0;
668 if (count > available - pos)
669 count = available - pos;
670 memcpy(to, from + pos, count);
671 *ppos = pos + count;
672
673 return count;
674}
675EXPORT_SYMBOL(memory_read_from_buffer);
676
677/*
678 * Transaction based IO.
679 * The file expects a single write which triggers the transaction, and then
680 * possibly a read which collects the result - which is stored in a
681 * file-local buffer.
682 */
683
684void simple_transaction_set(struct file *file, size_t n)
685{
686 struct simple_transaction_argresp *ar = file->private_data;
687
688 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
689
690 /*
691 * The barrier ensures that ar->size will really remain zero until
692 * ar->data is ready for reading.
693 */
694 smp_mb();
695 ar->size = n;
696}
697EXPORT_SYMBOL(simple_transaction_set);
698
699char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
700{
701 struct simple_transaction_argresp *ar;
702 static DEFINE_SPINLOCK(simple_transaction_lock);
703
704 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
705 return ERR_PTR(-EFBIG);
706
707 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
708 if (!ar)
709 return ERR_PTR(-ENOMEM);
710
711 spin_lock(&simple_transaction_lock);
712
713 /* only one write allowed per open */
714 if (file->private_data) {
715 spin_unlock(&simple_transaction_lock);
716 free_page((unsigned long)ar);
717 return ERR_PTR(-EBUSY);
718 }
719
720 file->private_data = ar;
721
722 spin_unlock(&simple_transaction_lock);
723
724 if (copy_from_user(ar->data, buf, size))
725 return ERR_PTR(-EFAULT);
726
727 return ar->data;
728}
729EXPORT_SYMBOL(simple_transaction_get);
730
731ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
732{
733 struct simple_transaction_argresp *ar = file->private_data;
734
735 if (!ar)
736 return 0;
737 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
738}
739EXPORT_SYMBOL(simple_transaction_read);
740
741int simple_transaction_release(struct inode *inode, struct file *file)
742{
743 free_page((unsigned long)file->private_data);
744 return 0;
745}
746EXPORT_SYMBOL(simple_transaction_release);
747
748/* Simple attribute files */
749
750struct simple_attr {
751 int (*get)(void *, u64 *);
752 int (*set)(void *, u64);
753 char get_buf[24]; /* enough to store a u64 and "\n\0" */
754 char set_buf[24];
755 void *data;
756 const char *fmt; /* format for read operation */
757 struct mutex mutex; /* protects access to these buffers */
758};
759
760/* simple_attr_open is called by an actual attribute open file operation
761 * to set the attribute specific access operations. */
762int simple_attr_open(struct inode *inode, struct file *file,
763 int (*get)(void *, u64 *), int (*set)(void *, u64),
764 const char *fmt)
765{
766 struct simple_attr *attr;
767
768 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
769 if (!attr)
770 return -ENOMEM;
771
772 attr->get = get;
773 attr->set = set;
774 attr->data = inode->i_private;
775 attr->fmt = fmt;
776 mutex_init(&attr->mutex);
777
778 file->private_data = attr;
779
780 return nonseekable_open(inode, file);
781}
782EXPORT_SYMBOL_GPL(simple_attr_open);
783
784int simple_attr_release(struct inode *inode, struct file *file)
785{
786 kfree(file->private_data);
787 return 0;
788}
789EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
790
791/* read from the buffer that is filled with the get function */
792ssize_t simple_attr_read(struct file *file, char __user *buf,
793 size_t len, loff_t *ppos)
794{
795 struct simple_attr *attr;
796 size_t size;
797 ssize_t ret;
798
799 attr = file->private_data;
800
801 if (!attr->get)
802 return -EACCES;
803
804 ret = mutex_lock_interruptible(&attr->mutex);
805 if (ret)
806 return ret;
807
808 if (*ppos) { /* continued read */
809 size = strlen(attr->get_buf);
810 } else { /* first read */
811 u64 val;
812 ret = attr->get(attr->data, &val);
813 if (ret)
814 goto out;
815
816 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
817 attr->fmt, (unsigned long long)val);
818 }
819
820 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
821out:
822 mutex_unlock(&attr->mutex);
823 return ret;
824}
825EXPORT_SYMBOL_GPL(simple_attr_read);
826
827/* interpret the buffer as a number to call the set function with */
828ssize_t simple_attr_write(struct file *file, const char __user *buf,
829 size_t len, loff_t *ppos)
830{
831 struct simple_attr *attr;
832 u64 val;
833 size_t size;
834 ssize_t ret;
835
836 attr = file->private_data;
837 if (!attr->set)
838 return -EACCES;
839
840 ret = mutex_lock_interruptible(&attr->mutex);
841 if (ret)
842 return ret;
843
844 ret = -EFAULT;
845 size = min(sizeof(attr->set_buf) - 1, len);
846 if (copy_from_user(attr->set_buf, buf, size))
847 goto out;
848
849 attr->set_buf[size] = '\0';
850 val = simple_strtoll(attr->set_buf, NULL, 0);
851 ret = attr->set(attr->data, val);
852 if (ret == 0)
853 ret = len; /* on success, claim we got the whole input */
854out:
855 mutex_unlock(&attr->mutex);
856 return ret;
857}
858EXPORT_SYMBOL_GPL(simple_attr_write);
859
860/**
861 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
862 * @sb: filesystem to do the file handle conversion on
863 * @fid: file handle to convert
864 * @fh_len: length of the file handle in bytes
865 * @fh_type: type of file handle
866 * @get_inode: filesystem callback to retrieve inode
867 *
868 * This function decodes @fid as long as it has one of the well-known
869 * Linux filehandle types and calls @get_inode on it to retrieve the
870 * inode for the object specified in the file handle.
871 */
872struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
873 int fh_len, int fh_type, struct inode *(*get_inode)
874 (struct super_block *sb, u64 ino, u32 gen))
875{
876 struct inode *inode = NULL;
877
878 if (fh_len < 2)
879 return NULL;
880
881 switch (fh_type) {
882 case FILEID_INO32_GEN:
883 case FILEID_INO32_GEN_PARENT:
884 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
885 break;
886 }
887
888 return d_obtain_alias(inode);
889}
890EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
891
892/**
893 * generic_fh_to_parent - generic helper for the fh_to_parent export operation
894 * @sb: filesystem to do the file handle conversion on
895 * @fid: file handle to convert
896 * @fh_len: length of the file handle in bytes
897 * @fh_type: type of file handle
898 * @get_inode: filesystem callback to retrieve inode
899 *
900 * This function decodes @fid as long as it has one of the well-known
901 * Linux filehandle types and calls @get_inode on it to retrieve the
902 * inode for the _parent_ object specified in the file handle if it
903 * is specified in the file handle, or NULL otherwise.
904 */
905struct dentry *generic_fh_to_parent(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_PARENT:
916 inode = get_inode(sb, fid->i32.parent_ino,
917 (fh_len > 3 ? fid->i32.parent_gen : 0));
918 break;
919 }
920
921 return d_obtain_alias(inode);
922}
923EXPORT_SYMBOL_GPL(generic_fh_to_parent);
924
925/**
926 * generic_file_fsync - generic fsync implementation for simple filesystems
927 * @file: file to synchronize
928 * @datasync: only synchronize essential metadata if true
929 *
930 * This is a generic implementation of the fsync method for simple
931 * filesystems which track all non-inode metadata in the buffers list
932 * hanging off the address_space structure.
933 */
934int generic_file_fsync(struct file *file, loff_t start, loff_t end,
935 int datasync)
936{
937 struct inode *inode = file->f_mapping->host;
938 int err;
939 int ret;
940
941 err = filemap_write_and_wait_range(inode->i_mapping, start, end);
942 if (err)
943 return err;
944
945 mutex_lock(&inode->i_mutex);
946 ret = sync_mapping_buffers(inode->i_mapping);
947 if (!(inode->i_state & I_DIRTY))
948 goto out;
949 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
950 goto out;
951
952 err = sync_inode_metadata(inode, 1);
953 if (ret == 0)
954 ret = err;
955out:
956 mutex_unlock(&inode->i_mutex);
957 return ret;
958}
959EXPORT_SYMBOL(generic_file_fsync);
960
961/**
962 * generic_check_addressable - Check addressability of file system
963 * @blocksize_bits: log of file system block size
964 * @num_blocks: number of blocks in file system
965 *
966 * Determine whether a file system with @num_blocks blocks (and a
967 * block size of 2**@blocksize_bits) is addressable by the sector_t
968 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
969 */
970int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
971{
972 u64 last_fs_block = num_blocks - 1;
973 u64 last_fs_page =
974 last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits);
975
976 if (unlikely(num_blocks == 0))
977 return 0;
978
979 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT))
980 return -EINVAL;
981
982 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
983 (last_fs_page > (pgoff_t)(~0ULL))) {
984 return -EFBIG;
985 }
986 return 0;
987}
988EXPORT_SYMBOL(generic_check_addressable);
989
990/*
991 * No-op implementation of ->fsync for in-memory filesystems.
992 */
993int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
994{
995 return 0;
996}
997EXPORT_SYMBOL(noop_fsync);
998
999void kfree_put_link(struct dentry *dentry, struct nameidata *nd,
1000 void *cookie)
1001{
1002 char *s = nd_get_link(nd);
1003 if (!IS_ERR(s))
1004 kfree(s);
1005}
1006EXPORT_SYMBOL(kfree_put_link);
1007
1008/*
1009 * nop .set_page_dirty method so that people can use .page_mkwrite on
1010 * anon inodes.
1011 */
1012static int anon_set_page_dirty(struct page *page)
1013{
1014 return 0;
1015};
1016
1017/*
1018 * A single inode exists for all anon_inode files. Contrary to pipes,
1019 * anon_inode inodes have no associated per-instance data, so we need
1020 * only allocate one of them.
1021 */
1022struct inode *alloc_anon_inode(struct super_block *s)
1023{
1024 static const struct address_space_operations anon_aops = {
1025 .set_page_dirty = anon_set_page_dirty,
1026 };
1027 struct inode *inode = new_inode_pseudo(s);
1028
1029 if (!inode)
1030 return ERR_PTR(-ENOMEM);
1031
1032 inode->i_ino = get_next_ino();
1033 inode->i_mapping->a_ops = &anon_aops;
1034
1035 /*
1036 * Mark the inode dirty from the very beginning,
1037 * that way it will never be moved to the dirty
1038 * list because mark_inode_dirty() will think
1039 * that it already _is_ on the dirty list.
1040 */
1041 inode->i_state = I_DIRTY;
1042 inode->i_mode = S_IRUSR | S_IWUSR;
1043 inode->i_uid = current_fsuid();
1044 inode->i_gid = current_fsgid();
1045 inode->i_flags |= S_PRIVATE;
1046 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1047 return inode;
1048}
1049EXPORT_SYMBOL(alloc_anon_inode);