blob: 80046ddf5063a41768e8063ac405ce5d55e92aef [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * fs/libfs.c
3 * Library for filesystems writers.
4 */
5
6#include <linux/module.h>
7#include <linux/pagemap.h>
8#include <linux/mount.h>
9#include <linux/vfs.h>
Ingo Molnar7cf34c72006-03-23 03:00:36 -080010#include <linux/mutex.h>
Christoph Hellwig25961102007-10-21 16:42:05 -070011#include <linux/exportfs.h>
Ingo Molnar7cf34c72006-03-23 03:00:36 -080012
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <asm/uaccess.h>
14
15int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
16 struct kstat *stat)
17{
18 struct inode *inode = dentry->d_inode;
19 generic_fillattr(inode, stat);
20 stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
21 return 0;
22}
23
David Howells726c3342006-06-23 02:02:58 -070024int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -070025{
David Howells726c3342006-06-23 02:02:58 -070026 buf->f_type = dentry->d_sb->s_magic;
Linus Torvalds1da177e2005-04-16 15:20:36 -070027 buf->f_bsize = PAGE_CACHE_SIZE;
28 buf->f_namelen = NAME_MAX;
29 return 0;
30}
31
32/*
33 * Retaining negative dentries for an in-memory filesystem just wastes
34 * memory and lookup time: arrange for them to be deleted immediately.
35 */
36static int simple_delete_dentry(struct dentry *dentry)
37{
38 return 1;
39}
40
41/*
42 * Lookup the data. This is trivial - if the dentry didn't already
43 * exist, we know it is negative. Set d_op to delete negative dentries.
44 */
45struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
46{
Al Viro3ba13d12009-02-20 06:02:22 +000047 static const struct dentry_operations simple_dentry_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 .d_delete = simple_delete_dentry,
49 };
50
51 if (dentry->d_name.len > NAME_MAX)
52 return ERR_PTR(-ENAMETOOLONG);
53 dentry->d_op = &simple_dentry_operations;
54 d_add(dentry, NULL);
55 return NULL;
56}
57
58int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
59{
60 return 0;
61}
62
63int dcache_dir_open(struct inode *inode, struct file *file)
64{
65 static struct qstr cursor_name = {.len = 1, .name = "."};
66
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -080067 file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -070068
69 return file->private_data ? 0 : -ENOMEM;
70}
71
72int dcache_dir_close(struct inode *inode, struct file *file)
73{
74 dput(file->private_data);
75 return 0;
76}
77
78loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
79{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -080080 mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 switch (origin) {
82 case 1:
83 offset += file->f_pos;
84 case 0:
85 if (offset >= 0)
86 break;
87 default:
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -080088 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 return -EINVAL;
90 }
91 if (offset != file->f_pos) {
92 file->f_pos = offset;
93 if (file->f_pos >= 2) {
94 struct list_head *p;
95 struct dentry *cursor = file->private_data;
96 loff_t n = file->f_pos - 2;
97
98 spin_lock(&dcache_lock);
Eric Dumazet5160ee62006-01-08 01:03:32 -080099 list_del(&cursor->d_u.d_child);
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800100 p = file->f_path.dentry->d_subdirs.next;
101 while (n && p != &file->f_path.dentry->d_subdirs) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 struct dentry *next;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800103 next = list_entry(p, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 if (!d_unhashed(next) && next->d_inode)
105 n--;
106 p = p->next;
107 }
Eric Dumazet5160ee62006-01-08 01:03:32 -0800108 list_add_tail(&cursor->d_u.d_child, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 spin_unlock(&dcache_lock);
110 }
111 }
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800112 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 return offset;
114}
115
116/* Relationship between i_mode and the DT_xxx types */
117static inline unsigned char dt_type(struct inode *inode)
118{
119 return (inode->i_mode >> 12) & 15;
120}
121
122/*
123 * Directory is locked and all positive dentries in it are safe, since
124 * for ramfs-type trees they can't go away without unlink() or rmdir(),
125 * both impossible due to the lock on directory.
126 */
127
128int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
129{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800130 struct dentry *dentry = filp->f_path.dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 struct dentry *cursor = filp->private_data;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800132 struct list_head *p, *q = &cursor->d_u.d_child;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 ino_t ino;
134 int i = filp->f_pos;
135
136 switch (i) {
137 case 0:
138 ino = dentry->d_inode->i_ino;
139 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
140 break;
141 filp->f_pos++;
142 i++;
143 /* fallthrough */
144 case 1:
145 ino = parent_ino(dentry);
146 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
147 break;
148 filp->f_pos++;
149 i++;
150 /* fallthrough */
151 default:
152 spin_lock(&dcache_lock);
Akinobu Mita1bfba4e2006-06-26 00:24:40 -0700153 if (filp->f_pos == 2)
154 list_move(q, &dentry->d_subdirs);
155
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
157 struct dentry *next;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800158 next = list_entry(p, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 if (d_unhashed(next) || !next->d_inode)
160 continue;
161
162 spin_unlock(&dcache_lock);
Ronni Nielsen0f8952c22007-05-09 06:44:57 +0200163 if (filldir(dirent, next->d_name.name,
164 next->d_name.len, filp->f_pos,
165 next->d_inode->i_ino,
166 dt_type(next->d_inode)) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 return 0;
168 spin_lock(&dcache_lock);
169 /* next is still alive */
Akinobu Mita1bfba4e2006-06-26 00:24:40 -0700170 list_move(q, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 p = q;
172 filp->f_pos++;
173 }
174 spin_unlock(&dcache_lock);
175 }
176 return 0;
177}
178
179ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
180{
181 return -EISDIR;
182}
183
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800184const struct file_operations simple_dir_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 .open = dcache_dir_open,
186 .release = dcache_dir_close,
187 .llseek = dcache_dir_lseek,
188 .read = generic_read_dir,
189 .readdir = dcache_readdir,
Hugh Dickins8ae0b772005-06-25 14:55:41 -0700190 .fsync = simple_sync_file,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191};
192
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800193const struct inode_operations simple_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 .lookup = simple_lookup,
195};
196
Hugh Dickins759b9772007-03-05 00:30:28 -0800197static const struct super_operations simple_super_operations = {
198 .statfs = simple_statfs,
199};
200
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201/*
202 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
203 * will never be mountable)
204 */
David Howells454e2392006-06-23 02:02:57 -0700205int get_sb_pseudo(struct file_system_type *fs_type, char *name,
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800206 const struct super_operations *ops, unsigned long magic,
David Howells454e2392006-06-23 02:02:57 -0700207 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208{
209 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 struct dentry *dentry;
211 struct inode *root;
212 struct qstr d_name = {.name = name, .len = strlen(name)};
213
214 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700215 return PTR_ERR(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
217 s->s_flags = MS_NOUSER;
218 s->s_maxbytes = ~0ULL;
Alex Nixon3971e1a2008-07-29 22:33:03 -0700219 s->s_blocksize = PAGE_SIZE;
220 s->s_blocksize_bits = PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 s->s_magic = magic;
Hugh Dickins759b9772007-03-05 00:30:28 -0800222 s->s_op = ops ? ops : &simple_super_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 s->s_time_gran = 1;
224 root = new_inode(s);
225 if (!root)
226 goto Enomem;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700227 /*
228 * since this is the first inode, make it number 1. New inodes created
229 * after this must take care not to collide with it (by passing
230 * max_reserved of 1 to iunique).
231 */
232 root->i_ino = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
235 dentry = d_alloc(NULL, &d_name);
236 if (!dentry) {
237 iput(root);
238 goto Enomem;
239 }
240 dentry->d_sb = s;
241 dentry->d_parent = dentry;
242 d_instantiate(dentry, root);
243 s->s_root = dentry;
244 s->s_flags |= MS_ACTIVE;
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -0800245 simple_set_mnt(mnt, s);
246 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247
248Enomem:
Al Viro6f5bbff2009-05-06 01:34:22 -0400249 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700250 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251}
252
253int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
254{
255 struct inode *inode = old_dentry->d_inode;
256
257 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -0700258 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 atomic_inc(&inode->i_count);
260 dget(dentry);
261 d_instantiate(dentry, inode);
262 return 0;
263}
264
265static inline int simple_positive(struct dentry *dentry)
266{
267 return dentry->d_inode && !d_unhashed(dentry);
268}
269
270int simple_empty(struct dentry *dentry)
271{
272 struct dentry *child;
273 int ret = 0;
274
275 spin_lock(&dcache_lock);
Eric Dumazet5160ee62006-01-08 01:03:32 -0800276 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277 if (simple_positive(child))
278 goto out;
279 ret = 1;
280out:
281 spin_unlock(&dcache_lock);
282 return ret;
283}
284
285int simple_unlink(struct inode *dir, struct dentry *dentry)
286{
287 struct inode *inode = dentry->d_inode;
288
289 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700290 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 dput(dentry);
292 return 0;
293}
294
295int simple_rmdir(struct inode *dir, struct dentry *dentry)
296{
297 if (!simple_empty(dentry))
298 return -ENOTEMPTY;
299
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700300 drop_nlink(dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 simple_unlink(dir, dentry);
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700302 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 return 0;
304}
305
306int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
307 struct inode *new_dir, struct dentry *new_dentry)
308{
309 struct inode *inode = old_dentry->d_inode;
310 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
311
312 if (!simple_empty(new_dentry))
313 return -ENOTEMPTY;
314
315 if (new_dentry->d_inode) {
316 simple_unlink(new_dir, new_dentry);
317 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700318 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700320 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -0700321 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 }
323
324 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
325 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
326
327 return 0;
328}
329
330int simple_readpage(struct file *file, struct page *page)
331{
Pekka J Enbergc0d92cb2006-09-29 01:59:09 -0700332 clear_highpage(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 flush_dcache_page(page);
334 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 unlock_page(page);
336 return 0;
337}
338
339int simple_prepare_write(struct file *file, struct page *page,
340 unsigned from, unsigned to)
341{
342 if (!PageUptodate(page)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -0800343 if (to - from != PAGE_CACHE_SIZE)
344 zero_user_segments(page,
345 0, from,
346 to, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 }
348 return 0;
349}
350
Nick Pigginafddba42007-10-16 01:25:01 -0700351int simple_write_begin(struct file *file, struct address_space *mapping,
352 loff_t pos, unsigned len, unsigned flags,
353 struct page **pagep, void **fsdata)
354{
355 struct page *page;
356 pgoff_t index;
357 unsigned from;
358
359 index = pos >> PAGE_CACHE_SHIFT;
360 from = pos & (PAGE_CACHE_SIZE - 1);
361
Nick Piggin54566b22009-01-04 12:00:53 -0800362 page = grab_cache_page_write_begin(mapping, index, flags);
Nick Pigginafddba42007-10-16 01:25:01 -0700363 if (!page)
364 return -ENOMEM;
365
366 *pagep = page;
367
368 return simple_prepare_write(file, page, from, from+len);
369}
370
Adrian Bunk4a239422007-10-16 23:27:16 -0700371static int simple_commit_write(struct file *file, struct page *page,
372 unsigned from, unsigned to)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373{
374 struct inode *inode = page->mapping->host;
375 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
376
Nick Piggin955eff52007-02-20 13:58:08 -0800377 if (!PageUptodate(page))
378 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 /*
380 * No need to use i_size_read() here, the i_size
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800381 * cannot change under us because we hold the i_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 */
383 if (pos > inode->i_size)
384 i_size_write(inode, pos);
385 set_page_dirty(page);
386 return 0;
387}
388
Nick Pigginafddba42007-10-16 01:25:01 -0700389int simple_write_end(struct file *file, struct address_space *mapping,
390 loff_t pos, unsigned len, unsigned copied,
391 struct page *page, void *fsdata)
392{
393 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
394
395 /* zero the stale part of the page if we did a short copy */
396 if (copied < len) {
397 void *kaddr = kmap_atomic(page, KM_USER0);
398 memset(kaddr + from + copied, 0, len - copied);
399 flush_dcache_page(page);
400 kunmap_atomic(kaddr, KM_USER0);
401 }
402
403 simple_commit_write(file, page, from, from+copied);
404
405 unlock_page(page);
406 page_cache_release(page);
407
408 return copied;
409}
410
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700411/*
412 * the inodes created here are not hashed. If you use iunique to generate
413 * unique inode values later for this filesystem, then you must take care
414 * to pass it an appropriate max_reserved value to avoid collisions.
415 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
417{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 struct inode *inode;
419 struct dentry *root;
420 struct dentry *dentry;
421 int i;
422
423 s->s_blocksize = PAGE_CACHE_SIZE;
424 s->s_blocksize_bits = PAGE_CACHE_SHIFT;
425 s->s_magic = magic;
Hugh Dickins759b9772007-03-05 00:30:28 -0800426 s->s_op = &simple_super_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 s->s_time_gran = 1;
428
429 inode = new_inode(s);
430 if (!inode)
431 return -ENOMEM;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700432 /*
433 * because the root inode is 1, the files array must not contain an
434 * entry at index 1
435 */
436 inode->i_ino = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 inode->i_mode = S_IFDIR | 0755;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
439 inode->i_op = &simple_dir_inode_operations;
440 inode->i_fop = &simple_dir_operations;
Vincent Hanquez7656f322006-02-03 03:04:48 -0800441 inode->i_nlink = 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 root = d_alloc_root(inode);
443 if (!root) {
444 iput(inode);
445 return -ENOMEM;
446 }
447 for (i = 0; !files->name || files->name[0]; i++, files++) {
448 if (!files->name)
449 continue;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700450
451 /* warn if it tries to conflict with the root inode */
452 if (unlikely(i == 1))
453 printk(KERN_WARNING "%s: %s passed in a files array"
454 "with an index of 1!\n", __func__,
455 s->s_type->name);
456
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 dentry = d_alloc_name(root, files->name);
458 if (!dentry)
459 goto out;
460 inode = new_inode(s);
461 if (!inode)
462 goto out;
463 inode->i_mode = S_IFREG | files->mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
465 inode->i_fop = files->ops;
466 inode->i_ino = i;
467 d_add(dentry, inode);
468 }
469 s->s_root = root;
470 return 0;
471out:
472 d_genocide(root);
473 dput(root);
474 return -ENOMEM;
475}
476
477static DEFINE_SPINLOCK(pin_fs_lock);
478
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400479int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480{
481 struct vfsmount *mnt = NULL;
482 spin_lock(&pin_fs_lock);
483 if (unlikely(!*mount)) {
484 spin_unlock(&pin_fs_lock);
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400485 mnt = vfs_kern_mount(type, 0, type->name, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 if (IS_ERR(mnt))
487 return PTR_ERR(mnt);
488 spin_lock(&pin_fs_lock);
489 if (!*mount)
490 *mount = mnt;
491 }
492 mntget(*mount);
493 ++*count;
494 spin_unlock(&pin_fs_lock);
495 mntput(mnt);
496 return 0;
497}
498
499void simple_release_fs(struct vfsmount **mount, int *count)
500{
501 struct vfsmount *mnt;
502 spin_lock(&pin_fs_lock);
503 mnt = *mount;
504 if (!--*count)
505 *mount = NULL;
506 spin_unlock(&pin_fs_lock);
507 mntput(mnt);
508}
509
Akinobu Mita6d1029b2008-07-04 09:59:51 -0700510/**
511 * simple_read_from_buffer - copy data from the buffer to user space
512 * @to: the user space buffer to read to
513 * @count: the maximum number of bytes to read
514 * @ppos: the current position in the buffer
515 * @from: the buffer to read from
516 * @available: the size of the buffer
517 *
518 * The simple_read_from_buffer() function reads up to @count bytes from the
519 * buffer @from at offset @ppos into the user space address starting at @to.
520 *
521 * On success, the number of bytes read is returned and the offset @ppos is
522 * advanced by this number, or negative value is returned on error.
523 **/
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
525 const void *from, size_t available)
526{
527 loff_t pos = *ppos;
528 if (pos < 0)
529 return -EINVAL;
530 if (pos >= available)
531 return 0;
532 if (count > available - pos)
533 count = available - pos;
534 if (copy_to_user(to, from + pos, count))
535 return -EFAULT;
536 *ppos = pos + count;
537 return count;
538}
539
Akinobu Mita6d1029b2008-07-04 09:59:51 -0700540/**
541 * memory_read_from_buffer - copy data from the buffer
542 * @to: the kernel space buffer to read to
543 * @count: the maximum number of bytes to read
544 * @ppos: the current position in the buffer
545 * @from: the buffer to read from
546 * @available: the size of the buffer
547 *
548 * The memory_read_from_buffer() function reads up to @count bytes from the
549 * buffer @from at offset @ppos into the kernel space address starting at @to.
550 *
551 * On success, the number of bytes read is returned and the offset @ppos is
552 * advanced by this number, or negative value is returned on error.
553 **/
Akinobu Mita93b07112008-06-05 22:46:21 -0700554ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
555 const void *from, size_t available)
556{
557 loff_t pos = *ppos;
558
559 if (pos < 0)
560 return -EINVAL;
561 if (pos >= available)
562 return 0;
563 if (count > available - pos)
564 count = available - pos;
565 memcpy(to, from + pos, count);
566 *ppos = pos + count;
567
568 return count;
569}
570
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571/*
572 * Transaction based IO.
573 * The file expects a single write which triggers the transaction, and then
574 * possibly a read which collects the result - which is stored in a
575 * file-local buffer.
576 */
Ingo Molnar76791ab2009-03-25 16:48:35 +0100577
578void simple_transaction_set(struct file *file, size_t n)
579{
580 struct simple_transaction_argresp *ar = file->private_data;
581
582 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
583
584 /*
585 * The barrier ensures that ar->size will really remain zero until
586 * ar->data is ready for reading.
587 */
588 smp_mb();
589 ar->size = n;
590}
591
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
593{
594 struct simple_transaction_argresp *ar;
595 static DEFINE_SPINLOCK(simple_transaction_lock);
596
597 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
598 return ERR_PTR(-EFBIG);
599
600 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
601 if (!ar)
602 return ERR_PTR(-ENOMEM);
603
604 spin_lock(&simple_transaction_lock);
605
606 /* only one write allowed per open */
607 if (file->private_data) {
608 spin_unlock(&simple_transaction_lock);
609 free_page((unsigned long)ar);
610 return ERR_PTR(-EBUSY);
611 }
612
613 file->private_data = ar;
614
615 spin_unlock(&simple_transaction_lock);
616
617 if (copy_from_user(ar->data, buf, size))
618 return ERR_PTR(-EFAULT);
619
620 return ar->data;
621}
622
623ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
624{
625 struct simple_transaction_argresp *ar = file->private_data;
626
627 if (!ar)
628 return 0;
629 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
630}
631
632int simple_transaction_release(struct inode *inode, struct file *file)
633{
634 free_page((unsigned long)file->private_data);
635 return 0;
636}
637
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200638/* Simple attribute files */
639
640struct simple_attr {
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800641 int (*get)(void *, u64 *);
642 int (*set)(void *, u64);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200643 char get_buf[24]; /* enough to store a u64 and "\n\0" */
644 char set_buf[24];
645 void *data;
646 const char *fmt; /* format for read operation */
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800647 struct mutex mutex; /* protects access to these buffers */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200648};
649
650/* simple_attr_open is called by an actual attribute open file operation
651 * to set the attribute specific access operations. */
652int simple_attr_open(struct inode *inode, struct file *file,
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800653 int (*get)(void *, u64 *), int (*set)(void *, u64),
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200654 const char *fmt)
655{
656 struct simple_attr *attr;
657
658 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
659 if (!attr)
660 return -ENOMEM;
661
662 attr->get = get;
663 attr->set = set;
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700664 attr->data = inode->i_private;
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200665 attr->fmt = fmt;
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800666 mutex_init(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200667
668 file->private_data = attr;
669
670 return nonseekable_open(inode, file);
671}
672
Christoph Hellwig74bedc42008-02-08 04:20:28 -0800673int simple_attr_release(struct inode *inode, struct file *file)
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200674{
675 kfree(file->private_data);
676 return 0;
677}
678
679/* read from the buffer that is filled with the get function */
680ssize_t simple_attr_read(struct file *file, char __user *buf,
681 size_t len, loff_t *ppos)
682{
683 struct simple_attr *attr;
684 size_t size;
685 ssize_t ret;
686
687 attr = file->private_data;
688
689 if (!attr->get)
690 return -EACCES;
691
Christoph Hellwig92613032008-02-08 04:20:27 -0800692 ret = mutex_lock_interruptible(&attr->mutex);
693 if (ret)
694 return ret;
695
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800696 if (*ppos) { /* continued read */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200697 size = strlen(attr->get_buf);
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800698 } else { /* first read */
699 u64 val;
700 ret = attr->get(attr->data, &val);
701 if (ret)
702 goto out;
703
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200704 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800705 attr->fmt, (unsigned long long)val);
706 }
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200707
708 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800709out:
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800710 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200711 return ret;
712}
713
714/* interpret the buffer as a number to call the set function with */
715ssize_t simple_attr_write(struct file *file, const char __user *buf,
716 size_t len, loff_t *ppos)
717{
718 struct simple_attr *attr;
719 u64 val;
720 size_t size;
721 ssize_t ret;
722
723 attr = file->private_data;
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200724 if (!attr->set)
725 return -EACCES;
726
Christoph Hellwig92613032008-02-08 04:20:27 -0800727 ret = mutex_lock_interruptible(&attr->mutex);
728 if (ret)
729 return ret;
730
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200731 ret = -EFAULT;
732 size = min(sizeof(attr->set_buf) - 1, len);
733 if (copy_from_user(attr->set_buf, buf, size))
734 goto out;
735
736 ret = len; /* claim we got the whole input */
737 attr->set_buf[size] = '\0';
738 val = simple_strtol(attr->set_buf, NULL, 0);
739 attr->set(attr->data, val);
740out:
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800741 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200742 return ret;
743}
744
Christoph Hellwig25961102007-10-21 16:42:05 -0700745/**
746 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
747 * @sb: filesystem to do the file handle conversion on
748 * @fid: file handle to convert
749 * @fh_len: length of the file handle in bytes
750 * @fh_type: type of file handle
751 * @get_inode: filesystem callback to retrieve inode
752 *
753 * This function decodes @fid as long as it has one of the well-known
754 * Linux filehandle types and calls @get_inode on it to retrieve the
755 * inode for the object specified in the file handle.
756 */
757struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
758 int fh_len, int fh_type, struct inode *(*get_inode)
759 (struct super_block *sb, u64 ino, u32 gen))
760{
761 struct inode *inode = NULL;
762
763 if (fh_len < 2)
764 return NULL;
765
766 switch (fh_type) {
767 case FILEID_INO32_GEN:
768 case FILEID_INO32_GEN_PARENT:
769 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
770 break;
771 }
772
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200773 return d_obtain_alias(inode);
Christoph Hellwig25961102007-10-21 16:42:05 -0700774}
775EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
776
777/**
778 * generic_fh_to_dentry - generic helper for the fh_to_parent export operation
779 * @sb: filesystem to do the file handle conversion on
780 * @fid: file handle to convert
781 * @fh_len: length of the file handle in bytes
782 * @fh_type: type of file handle
783 * @get_inode: filesystem callback to retrieve inode
784 *
785 * This function decodes @fid as long as it has one of the well-known
786 * Linux filehandle types and calls @get_inode on it to retrieve the
787 * inode for the _parent_ object specified in the file handle if it
788 * is specified in the file handle, or NULL otherwise.
789 */
790struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
791 int fh_len, int fh_type, struct inode *(*get_inode)
792 (struct super_block *sb, u64 ino, u32 gen))
793{
794 struct inode *inode = NULL;
795
796 if (fh_len <= 2)
797 return NULL;
798
799 switch (fh_type) {
800 case FILEID_INO32_GEN_PARENT:
801 inode = get_inode(sb, fid->i32.parent_ino,
802 (fh_len > 3 ? fid->i32.parent_gen : 0));
803 break;
804 }
805
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200806 return d_obtain_alias(inode);
Christoph Hellwig25961102007-10-21 16:42:05 -0700807}
808EXPORT_SYMBOL_GPL(generic_fh_to_parent);
809
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810EXPORT_SYMBOL(dcache_dir_close);
811EXPORT_SYMBOL(dcache_dir_lseek);
812EXPORT_SYMBOL(dcache_dir_open);
813EXPORT_SYMBOL(dcache_readdir);
814EXPORT_SYMBOL(generic_read_dir);
815EXPORT_SYMBOL(get_sb_pseudo);
Nick Pigginafddba42007-10-16 01:25:01 -0700816EXPORT_SYMBOL(simple_write_begin);
817EXPORT_SYMBOL(simple_write_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818EXPORT_SYMBOL(simple_dir_inode_operations);
819EXPORT_SYMBOL(simple_dir_operations);
820EXPORT_SYMBOL(simple_empty);
821EXPORT_SYMBOL(d_alloc_name);
822EXPORT_SYMBOL(simple_fill_super);
823EXPORT_SYMBOL(simple_getattr);
824EXPORT_SYMBOL(simple_link);
825EXPORT_SYMBOL(simple_lookup);
826EXPORT_SYMBOL(simple_pin_fs);
Nick Piggin4e02ed42008-10-29 14:00:55 -0700827EXPORT_UNUSED_SYMBOL(simple_prepare_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828EXPORT_SYMBOL(simple_readpage);
829EXPORT_SYMBOL(simple_release_fs);
830EXPORT_SYMBOL(simple_rename);
831EXPORT_SYMBOL(simple_rmdir);
832EXPORT_SYMBOL(simple_statfs);
833EXPORT_SYMBOL(simple_sync_file);
834EXPORT_SYMBOL(simple_unlink);
835EXPORT_SYMBOL(simple_read_from_buffer);
Akinobu Mita93b07112008-06-05 22:46:21 -0700836EXPORT_SYMBOL(memory_read_from_buffer);
Ingo Molnar76791ab2009-03-25 16:48:35 +0100837EXPORT_SYMBOL(simple_transaction_set);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838EXPORT_SYMBOL(simple_transaction_get);
839EXPORT_SYMBOL(simple_transaction_read);
840EXPORT_SYMBOL(simple_transaction_release);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200841EXPORT_SYMBOL_GPL(simple_attr_open);
Christoph Hellwig74bedc42008-02-08 04:20:28 -0800842EXPORT_SYMBOL_GPL(simple_attr_release);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200843EXPORT_SYMBOL_GPL(simple_attr_read);
844EXPORT_SYMBOL_GPL(simple_attr_write);