blob: 74688598bcf72ebadb7f978099f9691747369d6a [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{
47 static struct dentry_operations simple_dentry_operations = {
48 .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;
234 root->i_uid = root->i_gid = 0;
235 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
236 dentry = d_alloc(NULL, &d_name);
237 if (!dentry) {
238 iput(root);
239 goto Enomem;
240 }
241 dentry->d_sb = s;
242 dentry->d_parent = dentry;
243 d_instantiate(dentry, root);
244 s->s_root = dentry;
245 s->s_flags |= MS_ACTIVE;
David Howells454e2392006-06-23 02:02:57 -0700246 return simple_set_mnt(mnt, s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247
248Enomem:
249 up_write(&s->s_umount);
250 deactivate_super(s);
David Howells454e2392006-06-23 02:02:57 -0700251 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252}
253
254int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
255{
256 struct inode *inode = old_dentry->d_inode;
257
258 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -0700259 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 atomic_inc(&inode->i_count);
261 dget(dentry);
262 d_instantiate(dentry, inode);
263 return 0;
264}
265
266static inline int simple_positive(struct dentry *dentry)
267{
268 return dentry->d_inode && !d_unhashed(dentry);
269}
270
271int simple_empty(struct dentry *dentry)
272{
273 struct dentry *child;
274 int ret = 0;
275
276 spin_lock(&dcache_lock);
Eric Dumazet5160ee62006-01-08 01:03:32 -0800277 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 if (simple_positive(child))
279 goto out;
280 ret = 1;
281out:
282 spin_unlock(&dcache_lock);
283 return ret;
284}
285
286int simple_unlink(struct inode *dir, struct dentry *dentry)
287{
288 struct inode *inode = dentry->d_inode;
289
290 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700291 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 dput(dentry);
293 return 0;
294}
295
296int simple_rmdir(struct inode *dir, struct dentry *dentry)
297{
298 if (!simple_empty(dentry))
299 return -ENOTEMPTY;
300
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700301 drop_nlink(dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 simple_unlink(dir, dentry);
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700303 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 return 0;
305}
306
307int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
308 struct inode *new_dir, struct dentry *new_dentry)
309{
310 struct inode *inode = old_dentry->d_inode;
311 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
312
313 if (!simple_empty(new_dentry))
314 return -ENOTEMPTY;
315
316 if (new_dentry->d_inode) {
317 simple_unlink(new_dir, new_dentry);
318 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700319 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700321 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -0700322 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 }
324
325 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
326 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
327
328 return 0;
329}
330
331int simple_readpage(struct file *file, struct page *page)
332{
Pekka J Enbergc0d92cb2006-09-29 01:59:09 -0700333 clear_highpage(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 flush_dcache_page(page);
335 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 unlock_page(page);
337 return 0;
338}
339
340int simple_prepare_write(struct file *file, struct page *page,
341 unsigned from, unsigned to)
342{
343 if (!PageUptodate(page)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -0800344 if (to - from != PAGE_CACHE_SIZE)
345 zero_user_segments(page,
346 0, from,
347 to, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 }
349 return 0;
350}
351
Nick Pigginafddba42007-10-16 01:25:01 -0700352int simple_write_begin(struct file *file, struct address_space *mapping,
353 loff_t pos, unsigned len, unsigned flags,
354 struct page **pagep, void **fsdata)
355{
356 struct page *page;
357 pgoff_t index;
358 unsigned from;
359
360 index = pos >> PAGE_CACHE_SHIFT;
361 from = pos & (PAGE_CACHE_SIZE - 1);
362
363 page = __grab_cache_page(mapping, index);
364 if (!page)
365 return -ENOMEM;
366
367 *pagep = page;
368
369 return simple_prepare_write(file, page, from, from+len);
370}
371
Adrian Bunk4a239422007-10-16 23:27:16 -0700372static int simple_commit_write(struct file *file, struct page *page,
373 unsigned from, unsigned to)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374{
375 struct inode *inode = page->mapping->host;
376 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
377
Nick Piggin955eff52007-02-20 13:58:08 -0800378 if (!PageUptodate(page))
379 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 /*
381 * No need to use i_size_read() here, the i_size
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800382 * cannot change under us because we hold the i_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 */
384 if (pos > inode->i_size)
385 i_size_write(inode, pos);
386 set_page_dirty(page);
387 return 0;
388}
389
Nick Pigginafddba42007-10-16 01:25:01 -0700390int simple_write_end(struct file *file, struct address_space *mapping,
391 loff_t pos, unsigned len, unsigned copied,
392 struct page *page, void *fsdata)
393{
394 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
395
396 /* zero the stale part of the page if we did a short copy */
397 if (copied < len) {
398 void *kaddr = kmap_atomic(page, KM_USER0);
399 memset(kaddr + from + copied, 0, len - copied);
400 flush_dcache_page(page);
401 kunmap_atomic(kaddr, KM_USER0);
402 }
403
404 simple_commit_write(file, page, from, from+copied);
405
406 unlock_page(page);
407 page_cache_release(page);
408
409 return copied;
410}
411
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700412/*
413 * the inodes created here are not hashed. If you use iunique to generate
414 * unique inode values later for this filesystem, then you must take care
415 * to pass it an appropriate max_reserved value to avoid collisions.
416 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
418{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 struct inode *inode;
420 struct dentry *root;
421 struct dentry *dentry;
422 int i;
423
424 s->s_blocksize = PAGE_CACHE_SIZE;
425 s->s_blocksize_bits = PAGE_CACHE_SHIFT;
426 s->s_magic = magic;
Hugh Dickins759b9772007-03-05 00:30:28 -0800427 s->s_op = &simple_super_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 s->s_time_gran = 1;
429
430 inode = new_inode(s);
431 if (!inode)
432 return -ENOMEM;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700433 /*
434 * because the root inode is 1, the files array must not contain an
435 * entry at index 1
436 */
437 inode->i_ino = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 inode->i_mode = S_IFDIR | 0755;
439 inode->i_uid = inode->i_gid = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 inode->i_blocks = 0;
441 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
442 inode->i_op = &simple_dir_inode_operations;
443 inode->i_fop = &simple_dir_operations;
Vincent Hanquez7656f322006-02-03 03:04:48 -0800444 inode->i_nlink = 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 root = d_alloc_root(inode);
446 if (!root) {
447 iput(inode);
448 return -ENOMEM;
449 }
450 for (i = 0; !files->name || files->name[0]; i++, files++) {
451 if (!files->name)
452 continue;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700453
454 /* warn if it tries to conflict with the root inode */
455 if (unlikely(i == 1))
456 printk(KERN_WARNING "%s: %s passed in a files array"
457 "with an index of 1!\n", __func__,
458 s->s_type->name);
459
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 dentry = d_alloc_name(root, files->name);
461 if (!dentry)
462 goto out;
463 inode = new_inode(s);
464 if (!inode)
465 goto out;
466 inode->i_mode = S_IFREG | files->mode;
467 inode->i_uid = inode->i_gid = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 inode->i_blocks = 0;
469 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
470 inode->i_fop = files->ops;
471 inode->i_ino = i;
472 d_add(dentry, inode);
473 }
474 s->s_root = root;
475 return 0;
476out:
477 d_genocide(root);
478 dput(root);
479 return -ENOMEM;
480}
481
482static DEFINE_SPINLOCK(pin_fs_lock);
483
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400484int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485{
486 struct vfsmount *mnt = NULL;
487 spin_lock(&pin_fs_lock);
488 if (unlikely(!*mount)) {
489 spin_unlock(&pin_fs_lock);
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400490 mnt = vfs_kern_mount(type, 0, type->name, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 if (IS_ERR(mnt))
492 return PTR_ERR(mnt);
493 spin_lock(&pin_fs_lock);
494 if (!*mount)
495 *mount = mnt;
496 }
497 mntget(*mount);
498 ++*count;
499 spin_unlock(&pin_fs_lock);
500 mntput(mnt);
501 return 0;
502}
503
504void simple_release_fs(struct vfsmount **mount, int *count)
505{
506 struct vfsmount *mnt;
507 spin_lock(&pin_fs_lock);
508 mnt = *mount;
509 if (!--*count)
510 *mount = NULL;
511 spin_unlock(&pin_fs_lock);
512 mntput(mnt);
513}
514
Akinobu Mita6d1029b2008-07-04 09:59:51 -0700515/**
516 * simple_read_from_buffer - copy data from the buffer to user space
517 * @to: the user space buffer to read to
518 * @count: the maximum number of bytes to read
519 * @ppos: the current position in the buffer
520 * @from: the buffer to read from
521 * @available: the size of the buffer
522 *
523 * The simple_read_from_buffer() function reads up to @count bytes from the
524 * buffer @from at offset @ppos into the user space address starting at @to.
525 *
526 * On success, the number of bytes read is returned and the offset @ppos is
527 * advanced by this number, or negative value is returned on error.
528 **/
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
530 const void *from, size_t available)
531{
532 loff_t pos = *ppos;
533 if (pos < 0)
534 return -EINVAL;
535 if (pos >= available)
536 return 0;
537 if (count > available - pos)
538 count = available - pos;
539 if (copy_to_user(to, from + pos, count))
540 return -EFAULT;
541 *ppos = pos + count;
542 return count;
543}
544
Akinobu Mita6d1029b2008-07-04 09:59:51 -0700545/**
546 * memory_read_from_buffer - copy data from the buffer
547 * @to: the kernel space buffer to read to
548 * @count: the maximum number of bytes to read
549 * @ppos: the current position in the buffer
550 * @from: the buffer to read from
551 * @available: the size of the buffer
552 *
553 * The memory_read_from_buffer() function reads up to @count bytes from the
554 * buffer @from at offset @ppos into the kernel space address starting at @to.
555 *
556 * On success, the number of bytes read is returned and the offset @ppos is
557 * advanced by this number, or negative value is returned on error.
558 **/
Akinobu Mita93b07112008-06-05 22:46:21 -0700559ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
560 const void *from, size_t available)
561{
562 loff_t pos = *ppos;
563
564 if (pos < 0)
565 return -EINVAL;
566 if (pos >= available)
567 return 0;
568 if (count > available - pos)
569 count = available - pos;
570 memcpy(to, from + pos, count);
571 *ppos = pos + count;
572
573 return count;
574}
575
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576/*
577 * Transaction based IO.
578 * The file expects a single write which triggers the transaction, and then
579 * possibly a read which collects the result - which is stored in a
580 * file-local buffer.
581 */
582char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
583{
584 struct simple_transaction_argresp *ar;
585 static DEFINE_SPINLOCK(simple_transaction_lock);
586
587 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
588 return ERR_PTR(-EFBIG);
589
590 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
591 if (!ar)
592 return ERR_PTR(-ENOMEM);
593
594 spin_lock(&simple_transaction_lock);
595
596 /* only one write allowed per open */
597 if (file->private_data) {
598 spin_unlock(&simple_transaction_lock);
599 free_page((unsigned long)ar);
600 return ERR_PTR(-EBUSY);
601 }
602
603 file->private_data = ar;
604
605 spin_unlock(&simple_transaction_lock);
606
607 if (copy_from_user(ar->data, buf, size))
608 return ERR_PTR(-EFAULT);
609
610 return ar->data;
611}
612
613ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
614{
615 struct simple_transaction_argresp *ar = file->private_data;
616
617 if (!ar)
618 return 0;
619 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
620}
621
622int simple_transaction_release(struct inode *inode, struct file *file)
623{
624 free_page((unsigned long)file->private_data);
625 return 0;
626}
627
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200628/* Simple attribute files */
629
630struct simple_attr {
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800631 int (*get)(void *, u64 *);
632 int (*set)(void *, u64);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200633 char get_buf[24]; /* enough to store a u64 and "\n\0" */
634 char set_buf[24];
635 void *data;
636 const char *fmt; /* format for read operation */
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800637 struct mutex mutex; /* protects access to these buffers */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200638};
639
640/* simple_attr_open is called by an actual attribute open file operation
641 * to set the attribute specific access operations. */
642int simple_attr_open(struct inode *inode, struct file *file,
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800643 int (*get)(void *, u64 *), int (*set)(void *, u64),
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200644 const char *fmt)
645{
646 struct simple_attr *attr;
647
648 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
649 if (!attr)
650 return -ENOMEM;
651
652 attr->get = get;
653 attr->set = set;
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700654 attr->data = inode->i_private;
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200655 attr->fmt = fmt;
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800656 mutex_init(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200657
658 file->private_data = attr;
659
660 return nonseekable_open(inode, file);
661}
662
Christoph Hellwig74bedc42008-02-08 04:20:28 -0800663int simple_attr_release(struct inode *inode, struct file *file)
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200664{
665 kfree(file->private_data);
666 return 0;
667}
668
669/* read from the buffer that is filled with the get function */
670ssize_t simple_attr_read(struct file *file, char __user *buf,
671 size_t len, loff_t *ppos)
672{
673 struct simple_attr *attr;
674 size_t size;
675 ssize_t ret;
676
677 attr = file->private_data;
678
679 if (!attr->get)
680 return -EACCES;
681
Christoph Hellwig92613032008-02-08 04:20:27 -0800682 ret = mutex_lock_interruptible(&attr->mutex);
683 if (ret)
684 return ret;
685
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800686 if (*ppos) { /* continued read */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200687 size = strlen(attr->get_buf);
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800688 } else { /* first read */
689 u64 val;
690 ret = attr->get(attr->data, &val);
691 if (ret)
692 goto out;
693
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200694 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800695 attr->fmt, (unsigned long long)val);
696 }
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200697
698 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800699out:
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800700 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200701 return ret;
702}
703
704/* interpret the buffer as a number to call the set function with */
705ssize_t simple_attr_write(struct file *file, const char __user *buf,
706 size_t len, loff_t *ppos)
707{
708 struct simple_attr *attr;
709 u64 val;
710 size_t size;
711 ssize_t ret;
712
713 attr = file->private_data;
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200714 if (!attr->set)
715 return -EACCES;
716
Christoph Hellwig92613032008-02-08 04:20:27 -0800717 ret = mutex_lock_interruptible(&attr->mutex);
718 if (ret)
719 return ret;
720
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200721 ret = -EFAULT;
722 size = min(sizeof(attr->set_buf) - 1, len);
723 if (copy_from_user(attr->set_buf, buf, size))
724 goto out;
725
726 ret = len; /* claim we got the whole input */
727 attr->set_buf[size] = '\0';
728 val = simple_strtol(attr->set_buf, NULL, 0);
729 attr->set(attr->data, val);
730out:
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800731 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200732 return ret;
733}
734
Christoph Hellwig25961102007-10-21 16:42:05 -0700735/**
736 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
737 * @sb: filesystem to do the file handle conversion on
738 * @fid: file handle to convert
739 * @fh_len: length of the file handle in bytes
740 * @fh_type: type of file handle
741 * @get_inode: filesystem callback to retrieve inode
742 *
743 * This function decodes @fid as long as it has one of the well-known
744 * Linux filehandle types and calls @get_inode on it to retrieve the
745 * inode for the object specified in the file handle.
746 */
747struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
748 int fh_len, int fh_type, struct inode *(*get_inode)
749 (struct super_block *sb, u64 ino, u32 gen))
750{
751 struct inode *inode = NULL;
752
753 if (fh_len < 2)
754 return NULL;
755
756 switch (fh_type) {
757 case FILEID_INO32_GEN:
758 case FILEID_INO32_GEN_PARENT:
759 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
760 break;
761 }
762
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200763 return d_obtain_alias(inode);
Christoph Hellwig25961102007-10-21 16:42:05 -0700764}
765EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
766
767/**
768 * generic_fh_to_dentry - generic helper for the fh_to_parent export operation
769 * @sb: filesystem to do the file handle conversion on
770 * @fid: file handle to convert
771 * @fh_len: length of the file handle in bytes
772 * @fh_type: type of file handle
773 * @get_inode: filesystem callback to retrieve inode
774 *
775 * This function decodes @fid as long as it has one of the well-known
776 * Linux filehandle types and calls @get_inode on it to retrieve the
777 * inode for the _parent_ object specified in the file handle if it
778 * is specified in the file handle, or NULL otherwise.
779 */
780struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
781 int fh_len, int fh_type, struct inode *(*get_inode)
782 (struct super_block *sb, u64 ino, u32 gen))
783{
784 struct inode *inode = NULL;
785
786 if (fh_len <= 2)
787 return NULL;
788
789 switch (fh_type) {
790 case FILEID_INO32_GEN_PARENT:
791 inode = get_inode(sb, fid->i32.parent_ino,
792 (fh_len > 3 ? fid->i32.parent_gen : 0));
793 break;
794 }
795
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200796 return d_obtain_alias(inode);
Christoph Hellwig25961102007-10-21 16:42:05 -0700797}
798EXPORT_SYMBOL_GPL(generic_fh_to_parent);
799
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800EXPORT_SYMBOL(dcache_dir_close);
801EXPORT_SYMBOL(dcache_dir_lseek);
802EXPORT_SYMBOL(dcache_dir_open);
803EXPORT_SYMBOL(dcache_readdir);
804EXPORT_SYMBOL(generic_read_dir);
805EXPORT_SYMBOL(get_sb_pseudo);
Nick Pigginafddba42007-10-16 01:25:01 -0700806EXPORT_SYMBOL(simple_write_begin);
807EXPORT_SYMBOL(simple_write_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808EXPORT_SYMBOL(simple_dir_inode_operations);
809EXPORT_SYMBOL(simple_dir_operations);
810EXPORT_SYMBOL(simple_empty);
811EXPORT_SYMBOL(d_alloc_name);
812EXPORT_SYMBOL(simple_fill_super);
813EXPORT_SYMBOL(simple_getattr);
814EXPORT_SYMBOL(simple_link);
815EXPORT_SYMBOL(simple_lookup);
816EXPORT_SYMBOL(simple_pin_fs);
817EXPORT_SYMBOL(simple_prepare_write);
818EXPORT_SYMBOL(simple_readpage);
819EXPORT_SYMBOL(simple_release_fs);
820EXPORT_SYMBOL(simple_rename);
821EXPORT_SYMBOL(simple_rmdir);
822EXPORT_SYMBOL(simple_statfs);
823EXPORT_SYMBOL(simple_sync_file);
824EXPORT_SYMBOL(simple_unlink);
825EXPORT_SYMBOL(simple_read_from_buffer);
Akinobu Mita93b07112008-06-05 22:46:21 -0700826EXPORT_SYMBOL(memory_read_from_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827EXPORT_SYMBOL(simple_transaction_get);
828EXPORT_SYMBOL(simple_transaction_read);
829EXPORT_SYMBOL(simple_transaction_release);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200830EXPORT_SYMBOL_GPL(simple_attr_open);
Christoph Hellwig74bedc42008-02-08 04:20:28 -0800831EXPORT_SYMBOL_GPL(simple_attr_release);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200832EXPORT_SYMBOL_GPL(simple_attr_read);
833EXPORT_SYMBOL_GPL(simple_attr_write);