Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/fs/libfs.c

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

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us