blob: dcec3d3ea64f944cd51d36f35b4150279c5659f2 [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>
Al Virod5aacad2009-06-07 14:56:44 -040012#include <linux/writeback.h>
13#include <linux/buffer_head.h>
Ingo Molnar7cf34c72006-03-23 03:00:36 -080014
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <asm/uaccess.h>
16
17int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
18 struct kstat *stat)
19{
20 struct inode *inode = dentry->d_inode;
21 generic_fillattr(inode, stat);
22 stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
23 return 0;
24}
25
David Howells726c3342006-06-23 02:02:58 -070026int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -070027{
David Howells726c3342006-06-23 02:02:58 -070028 buf->f_type = dentry->d_sb->s_magic;
Linus Torvalds1da177e2005-04-16 15:20:36 -070029 buf->f_bsize = PAGE_CACHE_SIZE;
30 buf->f_namelen = NAME_MAX;
31 return 0;
32}
33
34/*
35 * Retaining negative dentries for an in-memory filesystem just wastes
36 * memory and lookup time: arrange for them to be deleted immediately.
37 */
38static int simple_delete_dentry(struct dentry *dentry)
39{
40 return 1;
41}
42
43/*
44 * Lookup the data. This is trivial - if the dentry didn't already
45 * exist, we know it is negative. Set d_op to delete negative dentries.
46 */
47struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
48{
Al Viro3ba13d12009-02-20 06:02:22 +000049 static const struct dentry_operations simple_dentry_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070050 .d_delete = simple_delete_dentry,
51 };
52
53 if (dentry->d_name.len > NAME_MAX)
54 return ERR_PTR(-ENAMETOOLONG);
55 dentry->d_op = &simple_dentry_operations;
56 d_add(dentry, NULL);
57 return NULL;
58}
59
60int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
61{
62 return 0;
63}
64
65int dcache_dir_open(struct inode *inode, struct file *file)
66{
67 static struct qstr cursor_name = {.len = 1, .name = "."};
68
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -080069 file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -070070
71 return file->private_data ? 0 : -ENOMEM;
72}
73
74int dcache_dir_close(struct inode *inode, struct file *file)
75{
76 dput(file->private_data);
77 return 0;
78}
79
80loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
81{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -080082 mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 switch (origin) {
84 case 1:
85 offset += file->f_pos;
86 case 0:
87 if (offset >= 0)
88 break;
89 default:
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -080090 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070091 return -EINVAL;
92 }
93 if (offset != file->f_pos) {
94 file->f_pos = offset;
95 if (file->f_pos >= 2) {
96 struct list_head *p;
97 struct dentry *cursor = file->private_data;
98 loff_t n = file->f_pos - 2;
99
100 spin_lock(&dcache_lock);
Eric Dumazet5160ee62006-01-08 01:03:32 -0800101 list_del(&cursor->d_u.d_child);
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800102 p = file->f_path.dentry->d_subdirs.next;
103 while (n && p != &file->f_path.dentry->d_subdirs) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 struct dentry *next;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800105 next = list_entry(p, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 if (!d_unhashed(next) && next->d_inode)
107 n--;
108 p = p->next;
109 }
Eric Dumazet5160ee62006-01-08 01:03:32 -0800110 list_add_tail(&cursor->d_u.d_child, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 spin_unlock(&dcache_lock);
112 }
113 }
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800114 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 return offset;
116}
117
118/* Relationship between i_mode and the DT_xxx types */
119static inline unsigned char dt_type(struct inode *inode)
120{
121 return (inode->i_mode >> 12) & 15;
122}
123
124/*
125 * Directory is locked and all positive dentries in it are safe, since
126 * for ramfs-type trees they can't go away without unlink() or rmdir(),
127 * both impossible due to the lock on directory.
128 */
129
130int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
131{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800132 struct dentry *dentry = filp->f_path.dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 struct dentry *cursor = filp->private_data;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800134 struct list_head *p, *q = &cursor->d_u.d_child;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 ino_t ino;
136 int i = filp->f_pos;
137
138 switch (i) {
139 case 0:
140 ino = dentry->d_inode->i_ino;
141 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
142 break;
143 filp->f_pos++;
144 i++;
145 /* fallthrough */
146 case 1:
147 ino = parent_ino(dentry);
148 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
149 break;
150 filp->f_pos++;
151 i++;
152 /* fallthrough */
153 default:
154 spin_lock(&dcache_lock);
Akinobu Mita1bfba4e2006-06-26 00:24:40 -0700155 if (filp->f_pos == 2)
156 list_move(q, &dentry->d_subdirs);
157
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
159 struct dentry *next;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800160 next = list_entry(p, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 if (d_unhashed(next) || !next->d_inode)
162 continue;
163
164 spin_unlock(&dcache_lock);
Ronni Nielsen0f8952c22007-05-09 06:44:57 +0200165 if (filldir(dirent, next->d_name.name,
166 next->d_name.len, filp->f_pos,
167 next->d_inode->i_ino,
168 dt_type(next->d_inode)) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169 return 0;
170 spin_lock(&dcache_lock);
171 /* next is still alive */
Akinobu Mita1bfba4e2006-06-26 00:24:40 -0700172 list_move(q, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 p = q;
174 filp->f_pos++;
175 }
176 spin_unlock(&dcache_lock);
177 }
178 return 0;
179}
180
181ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
182{
183 return -EISDIR;
184}
185
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800186const struct file_operations simple_dir_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 .open = dcache_dir_open,
188 .release = dcache_dir_close,
189 .llseek = dcache_dir_lseek,
190 .read = generic_read_dir,
191 .readdir = dcache_readdir,
Hugh Dickins8ae0b772005-06-25 14:55:41 -0700192 .fsync = simple_sync_file,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193};
194
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800195const struct inode_operations simple_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 .lookup = simple_lookup,
197};
198
Hugh Dickins759b9772007-03-05 00:30:28 -0800199static const struct super_operations simple_super_operations = {
200 .statfs = simple_statfs,
201};
202
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203/*
204 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
205 * will never be mountable)
206 */
David Howells454e2392006-06-23 02:02:57 -0700207int get_sb_pseudo(struct file_system_type *fs_type, char *name,
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800208 const struct super_operations *ops, unsigned long magic,
David Howells454e2392006-06-23 02:02:57 -0700209 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210{
211 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 struct dentry *dentry;
213 struct inode *root;
214 struct qstr d_name = {.name = name, .len = strlen(name)};
215
216 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700217 return PTR_ERR(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218
219 s->s_flags = MS_NOUSER;
Jeff Layton89a4eb42009-08-18 14:11:08 -0700220 s->s_maxbytes = MAX_LFS_FILESIZE;
Alex Nixon3971e1a2008-07-29 22:33:03 -0700221 s->s_blocksize = PAGE_SIZE;
222 s->s_blocksize_bits = PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 s->s_magic = magic;
Hugh Dickins759b9772007-03-05 00:30:28 -0800224 s->s_op = ops ? ops : &simple_super_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 s->s_time_gran = 1;
226 root = new_inode(s);
227 if (!root)
228 goto Enomem;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700229 /*
230 * since this is the first inode, make it number 1. New inodes created
231 * after this must take care not to collide with it (by passing
232 * max_reserved of 1 to iunique).
233 */
234 root->i_ino = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
237 dentry = d_alloc(NULL, &d_name);
238 if (!dentry) {
239 iput(root);
240 goto Enomem;
241 }
242 dentry->d_sb = s;
243 dentry->d_parent = dentry;
244 d_instantiate(dentry, root);
245 s->s_root = dentry;
246 s->s_flags |= MS_ACTIVE;
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -0800247 simple_set_mnt(mnt, s);
248 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249
250Enomem:
Al Viro6f5bbff2009-05-06 01:34:22 -0400251 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700252 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253}
254
255int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
256{
257 struct inode *inode = old_dentry->d_inode;
258
259 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -0700260 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 atomic_inc(&inode->i_count);
262 dget(dentry);
263 d_instantiate(dentry, inode);
264 return 0;
265}
266
267static inline int simple_positive(struct dentry *dentry)
268{
269 return dentry->d_inode && !d_unhashed(dentry);
270}
271
272int simple_empty(struct dentry *dentry)
273{
274 struct dentry *child;
275 int ret = 0;
276
277 spin_lock(&dcache_lock);
Eric Dumazet5160ee62006-01-08 01:03:32 -0800278 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 if (simple_positive(child))
280 goto out;
281 ret = 1;
282out:
283 spin_unlock(&dcache_lock);
284 return ret;
285}
286
287int simple_unlink(struct inode *dir, struct dentry *dentry)
288{
289 struct inode *inode = dentry->d_inode;
290
291 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700292 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 dput(dentry);
294 return 0;
295}
296
297int simple_rmdir(struct inode *dir, struct dentry *dentry)
298{
299 if (!simple_empty(dentry))
300 return -ENOTEMPTY;
301
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700302 drop_nlink(dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 simple_unlink(dir, dentry);
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700304 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 return 0;
306}
307
308int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
309 struct inode *new_dir, struct dentry *new_dentry)
310{
311 struct inode *inode = old_dentry->d_inode;
312 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
313
314 if (!simple_empty(new_dentry))
315 return -ENOTEMPTY;
316
317 if (new_dentry->d_inode) {
318 simple_unlink(new_dir, new_dentry);
319 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700320 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700322 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -0700323 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 }
325
326 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
327 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
328
329 return 0;
330}
331
332int simple_readpage(struct file *file, struct page *page)
333{
Pekka J Enbergc0d92cb2006-09-29 01:59:09 -0700334 clear_highpage(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 flush_dcache_page(page);
336 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 unlock_page(page);
338 return 0;
339}
340
341int simple_prepare_write(struct file *file, struct page *page,
342 unsigned from, unsigned to)
343{
344 if (!PageUptodate(page)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -0800345 if (to - from != PAGE_CACHE_SIZE)
346 zero_user_segments(page,
347 0, from,
348 to, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 }
350 return 0;
351}
352
Nick Pigginafddba42007-10-16 01:25:01 -0700353int simple_write_begin(struct file *file, struct address_space *mapping,
354 loff_t pos, unsigned len, unsigned flags,
355 struct page **pagep, void **fsdata)
356{
357 struct page *page;
358 pgoff_t index;
359 unsigned from;
360
361 index = pos >> PAGE_CACHE_SHIFT;
362 from = pos & (PAGE_CACHE_SIZE - 1);
363
Nick Piggin54566b22009-01-04 12:00:53 -0800364 page = grab_cache_page_write_begin(mapping, index, flags);
Nick Pigginafddba42007-10-16 01:25:01 -0700365 if (!page)
366 return -ENOMEM;
367
368 *pagep = page;
369
370 return simple_prepare_write(file, page, from, from+len);
371}
372
Adrian Bunk4a239422007-10-16 23:27:16 -0700373static int simple_commit_write(struct file *file, struct page *page,
374 unsigned from, unsigned to)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375{
376 struct inode *inode = page->mapping->host;
377 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
378
Nick Piggin955eff52007-02-20 13:58:08 -0800379 if (!PageUptodate(page))
380 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381 /*
382 * No need to use i_size_read() here, the i_size
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800383 * cannot change under us because we hold the i_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 */
385 if (pos > inode->i_size)
386 i_size_write(inode, pos);
387 set_page_dirty(page);
388 return 0;
389}
390
Nick Pigginafddba42007-10-16 01:25:01 -0700391int simple_write_end(struct file *file, struct address_space *mapping,
392 loff_t pos, unsigned len, unsigned copied,
393 struct page *page, void *fsdata)
394{
395 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
396
397 /* zero the stale part of the page if we did a short copy */
398 if (copied < len) {
399 void *kaddr = kmap_atomic(page, KM_USER0);
400 memset(kaddr + from + copied, 0, len - copied);
401 flush_dcache_page(page);
402 kunmap_atomic(kaddr, KM_USER0);
403 }
404
405 simple_commit_write(file, page, from, from+copied);
406
407 unlock_page(page);
408 page_cache_release(page);
409
410 return copied;
411}
412
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700413/*
414 * the inodes created here are not hashed. If you use iunique to generate
415 * unique inode values later for this filesystem, then you must take care
416 * to pass it an appropriate max_reserved value to avoid collisions.
417 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
419{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 struct inode *inode;
421 struct dentry *root;
422 struct dentry *dentry;
423 int i;
424
425 s->s_blocksize = PAGE_CACHE_SIZE;
426 s->s_blocksize_bits = PAGE_CACHE_SHIFT;
427 s->s_magic = magic;
Hugh Dickins759b9772007-03-05 00:30:28 -0800428 s->s_op = &simple_super_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 s->s_time_gran = 1;
430
431 inode = new_inode(s);
432 if (!inode)
433 return -ENOMEM;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700434 /*
435 * because the root inode is 1, the files array must not contain an
436 * entry at index 1
437 */
438 inode->i_ino = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439 inode->i_mode = S_IFDIR | 0755;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
441 inode->i_op = &simple_dir_inode_operations;
442 inode->i_fop = &simple_dir_operations;
Vincent Hanquez7656f322006-02-03 03:04:48 -0800443 inode->i_nlink = 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444 root = d_alloc_root(inode);
445 if (!root) {
446 iput(inode);
447 return -ENOMEM;
448 }
449 for (i = 0; !files->name || files->name[0]; i++, files++) {
450 if (!files->name)
451 continue;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700452
453 /* warn if it tries to conflict with the root inode */
454 if (unlikely(i == 1))
455 printk(KERN_WARNING "%s: %s passed in a files array"
456 "with an index of 1!\n", __func__,
457 s->s_type->name);
458
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 dentry = d_alloc_name(root, files->name);
460 if (!dentry)
461 goto out;
462 inode = new_inode(s);
463 if (!inode)
464 goto out;
465 inode->i_mode = S_IFREG | files->mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
467 inode->i_fop = files->ops;
468 inode->i_ino = i;
469 d_add(dentry, inode);
470 }
471 s->s_root = root;
472 return 0;
473out:
474 d_genocide(root);
475 dput(root);
476 return -ENOMEM;
477}
478
479static DEFINE_SPINLOCK(pin_fs_lock);
480
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400481int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482{
483 struct vfsmount *mnt = NULL;
484 spin_lock(&pin_fs_lock);
485 if (unlikely(!*mount)) {
486 spin_unlock(&pin_fs_lock);
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400487 mnt = vfs_kern_mount(type, 0, type->name, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 if (IS_ERR(mnt))
489 return PTR_ERR(mnt);
490 spin_lock(&pin_fs_lock);
491 if (!*mount)
492 *mount = mnt;
493 }
494 mntget(*mount);
495 ++*count;
496 spin_unlock(&pin_fs_lock);
497 mntput(mnt);
498 return 0;
499}
500
501void simple_release_fs(struct vfsmount **mount, int *count)
502{
503 struct vfsmount *mnt;
504 spin_lock(&pin_fs_lock);
505 mnt = *mount;
506 if (!--*count)
507 *mount = NULL;
508 spin_unlock(&pin_fs_lock);
509 mntput(mnt);
510}
511
Akinobu Mita6d1029b2008-07-04 09:59:51 -0700512/**
513 * simple_read_from_buffer - copy data from the buffer to user space
514 * @to: the user space buffer to read to
515 * @count: the maximum number of bytes to read
516 * @ppos: the current position in the buffer
517 * @from: the buffer to read from
518 * @available: the size of the buffer
519 *
520 * The simple_read_from_buffer() function reads up to @count bytes from the
521 * buffer @from at offset @ppos into the user space address starting at @to.
522 *
523 * On success, the number of bytes read is returned and the offset @ppos is
524 * advanced by this number, or negative value is returned on error.
525 **/
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
527 const void *from, size_t available)
528{
529 loff_t pos = *ppos;
530 if (pos < 0)
531 return -EINVAL;
532 if (pos >= available)
533 return 0;
534 if (count > available - pos)
535 count = available - pos;
536 if (copy_to_user(to, from + pos, count))
537 return -EFAULT;
538 *ppos = pos + count;
539 return count;
540}
541
Akinobu Mita6d1029b2008-07-04 09:59:51 -0700542/**
543 * memory_read_from_buffer - copy data from the buffer
544 * @to: the kernel space buffer to read to
545 * @count: the maximum number of bytes to read
546 * @ppos: the current position in the buffer
547 * @from: the buffer to read from
548 * @available: the size of the buffer
549 *
550 * The memory_read_from_buffer() function reads up to @count bytes from the
551 * buffer @from at offset @ppos into the kernel space address starting at @to.
552 *
553 * On success, the number of bytes read is returned and the offset @ppos is
554 * advanced by this number, or negative value is returned on error.
555 **/
Akinobu Mita93b07112008-06-05 22:46:21 -0700556ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
557 const void *from, size_t available)
558{
559 loff_t pos = *ppos;
560
561 if (pos < 0)
562 return -EINVAL;
563 if (pos >= available)
564 return 0;
565 if (count > available - pos)
566 count = available - pos;
567 memcpy(to, from + pos, count);
568 *ppos = pos + count;
569
570 return count;
571}
572
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573/*
574 * Transaction based IO.
575 * The file expects a single write which triggers the transaction, and then
576 * possibly a read which collects the result - which is stored in a
577 * file-local buffer.
578 */
Ingo Molnar76791ab2009-03-25 16:48:35 +0100579
580void simple_transaction_set(struct file *file, size_t n)
581{
582 struct simple_transaction_argresp *ar = file->private_data;
583
584 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
585
586 /*
587 * The barrier ensures that ar->size will really remain zero until
588 * ar->data is ready for reading.
589 */
590 smp_mb();
591 ar->size = n;
592}
593
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
595{
596 struct simple_transaction_argresp *ar;
597 static DEFINE_SPINLOCK(simple_transaction_lock);
598
599 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
600 return ERR_PTR(-EFBIG);
601
602 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
603 if (!ar)
604 return ERR_PTR(-ENOMEM);
605
606 spin_lock(&simple_transaction_lock);
607
608 /* only one write allowed per open */
609 if (file->private_data) {
610 spin_unlock(&simple_transaction_lock);
611 free_page((unsigned long)ar);
612 return ERR_PTR(-EBUSY);
613 }
614
615 file->private_data = ar;
616
617 spin_unlock(&simple_transaction_lock);
618
619 if (copy_from_user(ar->data, buf, size))
620 return ERR_PTR(-EFAULT);
621
622 return ar->data;
623}
624
625ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
626{
627 struct simple_transaction_argresp *ar = file->private_data;
628
629 if (!ar)
630 return 0;
631 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
632}
633
634int simple_transaction_release(struct inode *inode, struct file *file)
635{
636 free_page((unsigned long)file->private_data);
637 return 0;
638}
639
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200640/* Simple attribute files */
641
642struct simple_attr {
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800643 int (*get)(void *, u64 *);
644 int (*set)(void *, u64);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200645 char get_buf[24]; /* enough to store a u64 and "\n\0" */
646 char set_buf[24];
647 void *data;
648 const char *fmt; /* format for read operation */
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800649 struct mutex mutex; /* protects access to these buffers */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200650};
651
652/* simple_attr_open is called by an actual attribute open file operation
653 * to set the attribute specific access operations. */
654int simple_attr_open(struct inode *inode, struct file *file,
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800655 int (*get)(void *, u64 *), int (*set)(void *, u64),
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200656 const char *fmt)
657{
658 struct simple_attr *attr;
659
660 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
661 if (!attr)
662 return -ENOMEM;
663
664 attr->get = get;
665 attr->set = set;
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700666 attr->data = inode->i_private;
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200667 attr->fmt = fmt;
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800668 mutex_init(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200669
670 file->private_data = attr;
671
672 return nonseekable_open(inode, file);
673}
674
Christoph Hellwig74bedc42008-02-08 04:20:28 -0800675int simple_attr_release(struct inode *inode, struct file *file)
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200676{
677 kfree(file->private_data);
678 return 0;
679}
680
681/* read from the buffer that is filled with the get function */
682ssize_t simple_attr_read(struct file *file, char __user *buf,
683 size_t len, loff_t *ppos)
684{
685 struct simple_attr *attr;
686 size_t size;
687 ssize_t ret;
688
689 attr = file->private_data;
690
691 if (!attr->get)
692 return -EACCES;
693
Christoph Hellwig92613032008-02-08 04:20:27 -0800694 ret = mutex_lock_interruptible(&attr->mutex);
695 if (ret)
696 return ret;
697
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800698 if (*ppos) { /* continued read */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200699 size = strlen(attr->get_buf);
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800700 } else { /* first read */
701 u64 val;
702 ret = attr->get(attr->data, &val);
703 if (ret)
704 goto out;
705
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200706 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800707 attr->fmt, (unsigned long long)val);
708 }
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200709
710 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800711out:
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800712 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200713 return ret;
714}
715
716/* interpret the buffer as a number to call the set function with */
717ssize_t simple_attr_write(struct file *file, const char __user *buf,
718 size_t len, loff_t *ppos)
719{
720 struct simple_attr *attr;
721 u64 val;
722 size_t size;
723 ssize_t ret;
724
725 attr = file->private_data;
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200726 if (!attr->set)
727 return -EACCES;
728
Christoph Hellwig92613032008-02-08 04:20:27 -0800729 ret = mutex_lock_interruptible(&attr->mutex);
730 if (ret)
731 return ret;
732
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200733 ret = -EFAULT;
734 size = min(sizeof(attr->set_buf) - 1, len);
735 if (copy_from_user(attr->set_buf, buf, size))
736 goto out;
737
738 ret = len; /* claim we got the whole input */
739 attr->set_buf[size] = '\0';
740 val = simple_strtol(attr->set_buf, NULL, 0);
741 attr->set(attr->data, val);
742out:
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800743 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200744 return ret;
745}
746
Christoph Hellwig25961102007-10-21 16:42:05 -0700747/**
748 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
749 * @sb: filesystem to do the file handle conversion on
750 * @fid: file handle to convert
751 * @fh_len: length of the file handle in bytes
752 * @fh_type: type of file handle
753 * @get_inode: filesystem callback to retrieve inode
754 *
755 * This function decodes @fid as long as it has one of the well-known
756 * Linux filehandle types and calls @get_inode on it to retrieve the
757 * inode for the object specified in the file handle.
758 */
759struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
760 int fh_len, int fh_type, struct inode *(*get_inode)
761 (struct super_block *sb, u64 ino, u32 gen))
762{
763 struct inode *inode = NULL;
764
765 if (fh_len < 2)
766 return NULL;
767
768 switch (fh_type) {
769 case FILEID_INO32_GEN:
770 case FILEID_INO32_GEN_PARENT:
771 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
772 break;
773 }
774
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200775 return d_obtain_alias(inode);
Christoph Hellwig25961102007-10-21 16:42:05 -0700776}
777EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
778
779/**
780 * generic_fh_to_dentry - generic helper for the fh_to_parent export operation
781 * @sb: filesystem to do the file handle conversion on
782 * @fid: file handle to convert
783 * @fh_len: length of the file handle in bytes
784 * @fh_type: type of file handle
785 * @get_inode: filesystem callback to retrieve inode
786 *
787 * This function decodes @fid as long as it has one of the well-known
788 * Linux filehandle types and calls @get_inode on it to retrieve the
789 * inode for the _parent_ object specified in the file handle if it
790 * is specified in the file handle, or NULL otherwise.
791 */
792struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
793 int fh_len, int fh_type, struct inode *(*get_inode)
794 (struct super_block *sb, u64 ino, u32 gen))
795{
796 struct inode *inode = NULL;
797
798 if (fh_len <= 2)
799 return NULL;
800
801 switch (fh_type) {
802 case FILEID_INO32_GEN_PARENT:
803 inode = get_inode(sb, fid->i32.parent_ino,
804 (fh_len > 3 ? fid->i32.parent_gen : 0));
805 break;
806 }
807
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200808 return d_obtain_alias(inode);
Christoph Hellwig25961102007-10-21 16:42:05 -0700809}
810EXPORT_SYMBOL_GPL(generic_fh_to_parent);
811
Al Virod5aacad2009-06-07 14:56:44 -0400812int simple_fsync(struct file *file, struct dentry *dentry, int datasync)
813{
814 struct writeback_control wbc = {
815 .sync_mode = WB_SYNC_ALL,
816 .nr_to_write = 0, /* metadata-only; caller takes care of data */
817 };
818 struct inode *inode = dentry->d_inode;
819 int err;
820 int ret;
821
822 ret = sync_mapping_buffers(inode->i_mapping);
823 if (!(inode->i_state & I_DIRTY))
824 return ret;
825 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
826 return ret;
827
828 err = sync_inode(inode, &wbc);
829 if (ret == 0)
830 ret = err;
831 return ret;
832}
833EXPORT_SYMBOL(simple_fsync);
834
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835EXPORT_SYMBOL(dcache_dir_close);
836EXPORT_SYMBOL(dcache_dir_lseek);
837EXPORT_SYMBOL(dcache_dir_open);
838EXPORT_SYMBOL(dcache_readdir);
839EXPORT_SYMBOL(generic_read_dir);
840EXPORT_SYMBOL(get_sb_pseudo);
Nick Pigginafddba42007-10-16 01:25:01 -0700841EXPORT_SYMBOL(simple_write_begin);
842EXPORT_SYMBOL(simple_write_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843EXPORT_SYMBOL(simple_dir_inode_operations);
844EXPORT_SYMBOL(simple_dir_operations);
845EXPORT_SYMBOL(simple_empty);
846EXPORT_SYMBOL(d_alloc_name);
847EXPORT_SYMBOL(simple_fill_super);
848EXPORT_SYMBOL(simple_getattr);
849EXPORT_SYMBOL(simple_link);
850EXPORT_SYMBOL(simple_lookup);
851EXPORT_SYMBOL(simple_pin_fs);
Nick Piggin4e02ed42008-10-29 14:00:55 -0700852EXPORT_UNUSED_SYMBOL(simple_prepare_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853EXPORT_SYMBOL(simple_readpage);
854EXPORT_SYMBOL(simple_release_fs);
855EXPORT_SYMBOL(simple_rename);
856EXPORT_SYMBOL(simple_rmdir);
857EXPORT_SYMBOL(simple_statfs);
858EXPORT_SYMBOL(simple_sync_file);
859EXPORT_SYMBOL(simple_unlink);
860EXPORT_SYMBOL(simple_read_from_buffer);
Akinobu Mita93b07112008-06-05 22:46:21 -0700861EXPORT_SYMBOL(memory_read_from_buffer);
Ingo Molnar76791ab2009-03-25 16:48:35 +0100862EXPORT_SYMBOL(simple_transaction_set);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863EXPORT_SYMBOL(simple_transaction_get);
864EXPORT_SYMBOL(simple_transaction_read);
865EXPORT_SYMBOL(simple_transaction_release);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200866EXPORT_SYMBOL_GPL(simple_attr_open);
Christoph Hellwig74bedc42008-02-08 04:20:28 -0800867EXPORT_SYMBOL_GPL(simple_attr_release);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200868EXPORT_SYMBOL_GPL(simple_attr_read);
869EXPORT_SYMBOL_GPL(simple_attr_write);