3 * Library for filesystems writers.
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 */
19 #include <asm/uaccess.h>
23 int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
26 struct inode *inode = d_inode(dentry);
27 generic_fillattr(inode, stat);
28 stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
31 EXPORT_SYMBOL(simple_getattr);
33 int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
35 buf->f_type = dentry->d_sb->s_magic;
36 buf->f_bsize = PAGE_SIZE;
37 buf->f_namelen = NAME_MAX;
40 EXPORT_SYMBOL(simple_statfs);
43 * Retaining negative dentries for an in-memory filesystem just wastes
44 * memory and lookup time: arrange for them to be deleted immediately.
46 int always_delete_dentry(const struct dentry *dentry)
50 EXPORT_SYMBOL(always_delete_dentry);
52 const struct dentry_operations simple_dentry_operations = {
53 .d_delete = always_delete_dentry,
55 EXPORT_SYMBOL(simple_dentry_operations);
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.
61 struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
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);
70 EXPORT_SYMBOL(simple_lookup);
72 int dcache_dir_open(struct inode *inode, struct file *file)
74 file->private_data = d_alloc_cursor(file->f_path.dentry);
76 return file->private_data ? 0 : -ENOMEM;
78 EXPORT_SYMBOL(dcache_dir_open);
80 int dcache_dir_close(struct inode *inode, struct file *file)
82 dput(file->private_data);
85 EXPORT_SYMBOL(dcache_dir_close);
87 /* parent is locked at least shared */
88 static struct dentry *next_positive(struct dentry *parent,
89 struct list_head *from,
92 unsigned *seq = &parent->d_inode->i_dir_seq, n;
101 n = smp_load_acquire(seq) & ~1;
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)) {
116 if (unlikely(*seq != n))
122 static void move_cursor(struct dentry *cursor, struct list_head *after)
124 struct dentry *parent = cursor->d_parent;
125 unsigned n, *seq = &parent->d_inode->i_dir_seq;
126 spin_lock(&parent->d_lock);
129 if (!(n & 1) && cmpxchg(seq, n, n + 1) == n)
133 __list_del(cursor->d_child.prev, cursor->d_child.next);
135 list_add(&cursor->d_child, after);
137 list_add_tail(&cursor->d_child, &parent->d_subdirs);
138 smp_store_release(seq, n + 2);
139 spin_unlock(&parent->d_lock);
142 loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
144 struct dentry *dentry = file->f_path.dentry;
147 offset += file->f_pos;
154 if (offset != file->f_pos) {
155 file->f_pos = offset;
156 if (file->f_pos >= 2) {
157 struct dentry *cursor = file->private_data;
159 loff_t n = file->f_pos - 2;
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);
169 EXPORT_SYMBOL(dcache_dir_lseek);
171 /* Relationship between i_mode and the DT_xxx types */
172 static inline unsigned char dt_type(struct inode *inode)
174 return (inode->i_mode >> 12) & 15;
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.
183 int dcache_readdir(struct file *file, struct dir_context *ctx)
185 struct dentry *dentry = file->f_path.dentry;
186 struct dentry *cursor = file->private_data;
187 struct list_head *p = &cursor->d_child;
191 if (!dir_emit_dots(file, ctx))
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))))
205 move_cursor(cursor, p);
208 EXPORT_SYMBOL(dcache_readdir);
210 ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
214 EXPORT_SYMBOL(generic_read_dir);
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,
224 EXPORT_SYMBOL(simple_dir_operations);
226 const struct inode_operations simple_dir_inode_operations = {
227 .lookup = simple_lookup,
229 EXPORT_SYMBOL(simple_dir_inode_operations);
231 static const struct super_operations simple_super_operations = {
232 .statfs = simple_statfs,
236 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
237 * will never be mountable)
239 struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name,
240 const struct super_operations *ops,
241 const struct dentry_operations *dops, unsigned long magic)
243 struct super_block *s;
244 struct dentry *dentry;
246 struct qstr d_name = QSTR_INIT(name, strlen(name));
248 s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL);
252 s->s_maxbytes = MAX_LFS_FILESIZE;
253 s->s_blocksize = PAGE_SIZE;
254 s->s_blocksize_bits = PAGE_SHIFT;
256 s->s_op = ops ? ops : &simple_super_operations;
262 * since this is the first inode, make it number 1. New inodes created
263 * after this must take care not to collide with it (by passing
264 * max_reserved of 1 to iunique).
267 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
268 root->i_atime = root->i_mtime = root->i_ctime = current_time(root);
269 dentry = __d_alloc(s, &d_name);
274 d_instantiate(dentry, root);
277 s->s_flags |= MS_ACTIVE;
278 return dget(s->s_root);
281 deactivate_locked_super(s);
282 return ERR_PTR(-ENOMEM);
284 EXPORT_SYMBOL(mount_pseudo);
286 int simple_open(struct inode *inode, struct file *file)
288 if (inode->i_private)
289 file->private_data = inode->i_private;
292 EXPORT_SYMBOL(simple_open);
294 int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
296 struct inode *inode = d_inode(old_dentry);
298 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
302 d_instantiate(dentry, inode);
305 EXPORT_SYMBOL(simple_link);
307 int simple_empty(struct dentry *dentry)
309 struct dentry *child;
312 spin_lock(&dentry->d_lock);
313 list_for_each_entry(child, &dentry->d_subdirs, d_child) {
314 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
315 if (simple_positive(child)) {
316 spin_unlock(&child->d_lock);
319 spin_unlock(&child->d_lock);
323 spin_unlock(&dentry->d_lock);
326 EXPORT_SYMBOL(simple_empty);
328 int simple_unlink(struct inode *dir, struct dentry *dentry)
330 struct inode *inode = d_inode(dentry);
332 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
337 EXPORT_SYMBOL(simple_unlink);
339 int simple_rmdir(struct inode *dir, struct dentry *dentry)
341 if (!simple_empty(dentry))
344 drop_nlink(d_inode(dentry));
345 simple_unlink(dir, dentry);
349 EXPORT_SYMBOL(simple_rmdir);
351 int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
352 struct inode *new_dir, struct dentry *new_dentry,
355 struct inode *inode = d_inode(old_dentry);
356 int they_are_dirs = d_is_dir(old_dentry);
358 if (flags & ~RENAME_NOREPLACE)
361 if (!simple_empty(new_dentry))
364 if (d_really_is_positive(new_dentry)) {
365 simple_unlink(new_dir, new_dentry);
367 drop_nlink(d_inode(new_dentry));
370 } else if (they_are_dirs) {
375 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
376 new_dir->i_mtime = inode->i_ctime = current_time(old_dir);
380 EXPORT_SYMBOL(simple_rename);
383 * simple_setattr - setattr for simple filesystem
385 * @iattr: iattr structure
387 * Returns 0 on success, -error on failure.
389 * simple_setattr is a simple ->setattr implementation without a proper
390 * implementation of size changes.
392 * It can either be used for in-memory filesystems or special files
393 * on simple regular filesystems. Anything that needs to change on-disk
394 * or wire state on size changes needs its own setattr method.
396 int simple_setattr(struct dentry *dentry, struct iattr *iattr)
398 struct inode *inode = d_inode(dentry);
401 error = inode_change_ok(inode, iattr);
405 if (iattr->ia_valid & ATTR_SIZE)
406 truncate_setsize(inode, iattr->ia_size);
407 setattr_copy(inode, iattr);
408 mark_inode_dirty(inode);
411 EXPORT_SYMBOL(simple_setattr);
413 int simple_readpage(struct file *file, struct page *page)
415 clear_highpage(page);
416 flush_dcache_page(page);
417 SetPageUptodate(page);
421 EXPORT_SYMBOL(simple_readpage);
423 int simple_write_begin(struct file *file, struct address_space *mapping,
424 loff_t pos, unsigned len, unsigned flags,
425 struct page **pagep, void **fsdata)
430 index = pos >> PAGE_SHIFT;
432 page = grab_cache_page_write_begin(mapping, index, flags);
438 if (!PageUptodate(page) && (len != PAGE_SIZE)) {
439 unsigned from = pos & (PAGE_SIZE - 1);
441 zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
445 EXPORT_SYMBOL(simple_write_begin);
448 * simple_write_end - .write_end helper for non-block-device FSes
449 * @available: See .write_end of address_space_operations
458 * simple_write_end does the minimum needed for updating a page after writing is
459 * done. It has the same API signature as the .write_end of
460 * address_space_operations vector. So it can just be set onto .write_end for
461 * FSes that don't need any other processing. i_mutex is assumed to be held.
462 * Block based filesystems should use generic_write_end().
463 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
464 * is not called, so a filesystem that actually does store data in .write_inode
465 * should extend on what's done here with a call to mark_inode_dirty() in the
466 * case that i_size has changed.
468 int simple_write_end(struct file *file, struct address_space *mapping,
469 loff_t pos, unsigned len, unsigned copied,
470 struct page *page, void *fsdata)
472 struct inode *inode = page->mapping->host;
473 loff_t last_pos = pos + copied;
475 /* zero the stale part of the page if we did a short copy */
477 unsigned from = pos & (PAGE_SIZE - 1);
479 zero_user(page, from + copied, len - copied);
482 if (!PageUptodate(page))
483 SetPageUptodate(page);
485 * No need to use i_size_read() here, the i_size
486 * cannot change under us because we hold the i_mutex.
488 if (last_pos > inode->i_size)
489 i_size_write(inode, last_pos);
491 set_page_dirty(page);
497 EXPORT_SYMBOL(simple_write_end);
500 * the inodes created here are not hashed. If you use iunique to generate
501 * unique inode values later for this filesystem, then you must take care
502 * to pass it an appropriate max_reserved value to avoid collisions.
504 int simple_fill_super(struct super_block *s, unsigned long magic,
505 struct tree_descr *files)
509 struct dentry *dentry;
512 s->s_blocksize = PAGE_SIZE;
513 s->s_blocksize_bits = PAGE_SHIFT;
515 s->s_op = &simple_super_operations;
518 inode = new_inode(s);
522 * because the root inode is 1, the files array must not contain an
526 inode->i_mode = S_IFDIR | 0755;
527 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
528 inode->i_op = &simple_dir_inode_operations;
529 inode->i_fop = &simple_dir_operations;
531 root = d_make_root(inode);
534 for (i = 0; !files->name || files->name[0]; i++, files++) {
538 /* warn if it tries to conflict with the root inode */
539 if (unlikely(i == 1))
540 printk(KERN_WARNING "%s: %s passed in a files array"
541 "with an index of 1!\n", __func__,
544 dentry = d_alloc_name(root, files->name);
547 inode = new_inode(s);
552 inode->i_mode = S_IFREG | files->mode;
553 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
554 inode->i_fop = files->ops;
556 d_add(dentry, inode);
562 shrink_dcache_parent(root);
566 EXPORT_SYMBOL(simple_fill_super);
568 static DEFINE_SPINLOCK(pin_fs_lock);
570 int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
572 struct vfsmount *mnt = NULL;
573 spin_lock(&pin_fs_lock);
574 if (unlikely(!*mount)) {
575 spin_unlock(&pin_fs_lock);
576 mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, NULL);
579 spin_lock(&pin_fs_lock);
585 spin_unlock(&pin_fs_lock);
589 EXPORT_SYMBOL(simple_pin_fs);
591 void simple_release_fs(struct vfsmount **mount, int *count)
593 struct vfsmount *mnt;
594 spin_lock(&pin_fs_lock);
598 spin_unlock(&pin_fs_lock);
601 EXPORT_SYMBOL(simple_release_fs);
604 * simple_read_from_buffer - copy data from the buffer to user space
605 * @to: the user space buffer to read to
606 * @count: the maximum number of bytes to read
607 * @ppos: the current position in the buffer
608 * @from: the buffer to read from
609 * @available: the size of the buffer
611 * The simple_read_from_buffer() function reads up to @count bytes from the
612 * buffer @from at offset @ppos into the user space address starting at @to.
614 * On success, the number of bytes read is returned and the offset @ppos is
615 * advanced by this number, or negative value is returned on error.
617 ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
618 const void *from, size_t available)
625 if (pos >= available || !count)
627 if (count > available - pos)
628 count = available - pos;
629 ret = copy_to_user(to, from + pos, count);
636 EXPORT_SYMBOL(simple_read_from_buffer);
639 * simple_write_to_buffer - copy data from user space to the buffer
640 * @to: the buffer to write to
641 * @available: the size of the buffer
642 * @ppos: the current position in the buffer
643 * @from: the user space buffer to read from
644 * @count: the maximum number of bytes to read
646 * The simple_write_to_buffer() function reads up to @count bytes from the user
647 * space address starting at @from into the buffer @to at offset @ppos.
649 * On success, the number of bytes written is returned and the offset @ppos is
650 * advanced by this number, or negative value is returned on error.
652 ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
653 const void __user *from, size_t count)
660 if (pos >= available || !count)
662 if (count > available - pos)
663 count = available - pos;
664 res = copy_from_user(to + pos, from, count);
671 EXPORT_SYMBOL(simple_write_to_buffer);
674 * memory_read_from_buffer - copy data from the buffer
675 * @to: the kernel space buffer to read to
676 * @count: the maximum number of bytes to read
677 * @ppos: the current position in the buffer
678 * @from: the buffer to read from
679 * @available: the size of the buffer
681 * The memory_read_from_buffer() function reads up to @count bytes from the
682 * buffer @from at offset @ppos into the kernel space address starting at @to.
684 * On success, the number of bytes read is returned and the offset @ppos is
685 * advanced by this number, or negative value is returned on error.
687 ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
688 const void *from, size_t available)
694 if (pos >= available)
696 if (count > available - pos)
697 count = available - pos;
698 memcpy(to, from + pos, count);
703 EXPORT_SYMBOL(memory_read_from_buffer);
706 * Transaction based IO.
707 * The file expects a single write which triggers the transaction, and then
708 * possibly a read which collects the result - which is stored in a
712 void simple_transaction_set(struct file *file, size_t n)
714 struct simple_transaction_argresp *ar = file->private_data;
716 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
719 * The barrier ensures that ar->size will really remain zero until
720 * ar->data is ready for reading.
725 EXPORT_SYMBOL(simple_transaction_set);
727 char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
729 struct simple_transaction_argresp *ar;
730 static DEFINE_SPINLOCK(simple_transaction_lock);
732 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
733 return ERR_PTR(-EFBIG);
735 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
737 return ERR_PTR(-ENOMEM);
739 spin_lock(&simple_transaction_lock);
741 /* only one write allowed per open */
742 if (file->private_data) {
743 spin_unlock(&simple_transaction_lock);
744 free_page((unsigned long)ar);
745 return ERR_PTR(-EBUSY);
748 file->private_data = ar;
750 spin_unlock(&simple_transaction_lock);
752 if (copy_from_user(ar->data, buf, size))
753 return ERR_PTR(-EFAULT);
757 EXPORT_SYMBOL(simple_transaction_get);
759 ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
761 struct simple_transaction_argresp *ar = file->private_data;
765 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
767 EXPORT_SYMBOL(simple_transaction_read);
769 int simple_transaction_release(struct inode *inode, struct file *file)
771 free_page((unsigned long)file->private_data);
774 EXPORT_SYMBOL(simple_transaction_release);
776 /* Simple attribute files */
779 int (*get)(void *, u64 *);
780 int (*set)(void *, u64);
781 char get_buf[24]; /* enough to store a u64 and "\n\0" */
784 const char *fmt; /* format for read operation */
785 struct mutex mutex; /* protects access to these buffers */
788 /* simple_attr_open is called by an actual attribute open file operation
789 * to set the attribute specific access operations. */
790 int simple_attr_open(struct inode *inode, struct file *file,
791 int (*get)(void *, u64 *), int (*set)(void *, u64),
794 struct simple_attr *attr;
796 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
802 attr->data = inode->i_private;
804 mutex_init(&attr->mutex);
806 file->private_data = attr;
808 return nonseekable_open(inode, file);
810 EXPORT_SYMBOL_GPL(simple_attr_open);
812 int simple_attr_release(struct inode *inode, struct file *file)
814 kfree(file->private_data);
817 EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
819 /* read from the buffer that is filled with the get function */
820 ssize_t simple_attr_read(struct file *file, char __user *buf,
821 size_t len, loff_t *ppos)
823 struct simple_attr *attr;
827 attr = file->private_data;
832 ret = mutex_lock_interruptible(&attr->mutex);
836 if (*ppos) { /* continued read */
837 size = strlen(attr->get_buf);
838 } else { /* first read */
840 ret = attr->get(attr->data, &val);
844 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
845 attr->fmt, (unsigned long long)val);
848 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
850 mutex_unlock(&attr->mutex);
853 EXPORT_SYMBOL_GPL(simple_attr_read);
855 /* interpret the buffer as a number to call the set function with */
856 ssize_t simple_attr_write(struct file *file, const char __user *buf,
857 size_t len, loff_t *ppos)
859 struct simple_attr *attr;
864 attr = file->private_data;
868 ret = mutex_lock_interruptible(&attr->mutex);
873 size = min(sizeof(attr->set_buf) - 1, len);
874 if (copy_from_user(attr->set_buf, buf, size))
877 attr->set_buf[size] = '\0';
878 val = simple_strtoll(attr->set_buf, NULL, 0);
879 ret = attr->set(attr->data, val);
881 ret = len; /* on success, claim we got the whole input */
883 mutex_unlock(&attr->mutex);
886 EXPORT_SYMBOL_GPL(simple_attr_write);
889 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
890 * @sb: filesystem to do the file handle conversion on
891 * @fid: file handle to convert
892 * @fh_len: length of the file handle in bytes
893 * @fh_type: type of file handle
894 * @get_inode: filesystem callback to retrieve inode
896 * This function decodes @fid as long as it has one of the well-known
897 * Linux filehandle types and calls @get_inode on it to retrieve the
898 * inode for the object specified in the file handle.
900 struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
901 int fh_len, int fh_type, struct inode *(*get_inode)
902 (struct super_block *sb, u64 ino, u32 gen))
904 struct inode *inode = NULL;
910 case FILEID_INO32_GEN:
911 case FILEID_INO32_GEN_PARENT:
912 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
916 return d_obtain_alias(inode);
918 EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
921 * generic_fh_to_parent - generic helper for the fh_to_parent export operation
922 * @sb: filesystem to do the file handle conversion on
923 * @fid: file handle to convert
924 * @fh_len: length of the file handle in bytes
925 * @fh_type: type of file handle
926 * @get_inode: filesystem callback to retrieve inode
928 * This function decodes @fid as long as it has one of the well-known
929 * Linux filehandle types and calls @get_inode on it to retrieve the
930 * inode for the _parent_ object specified in the file handle if it
931 * is specified in the file handle, or NULL otherwise.
933 struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
934 int fh_len, int fh_type, struct inode *(*get_inode)
935 (struct super_block *sb, u64 ino, u32 gen))
937 struct inode *inode = NULL;
943 case FILEID_INO32_GEN_PARENT:
944 inode = get_inode(sb, fid->i32.parent_ino,
945 (fh_len > 3 ? fid->i32.parent_gen : 0));
949 return d_obtain_alias(inode);
951 EXPORT_SYMBOL_GPL(generic_fh_to_parent);
954 * __generic_file_fsync - generic fsync implementation for simple filesystems
956 * @file: file to synchronize
957 * @start: start offset in bytes
958 * @end: end offset in bytes (inclusive)
959 * @datasync: only synchronize essential metadata if true
961 * This is a generic implementation of the fsync method for simple
962 * filesystems which track all non-inode metadata in the buffers list
963 * hanging off the address_space structure.
965 int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
968 struct inode *inode = file->f_mapping->host;
972 err = filemap_write_and_wait_range(inode->i_mapping, start, end);
977 ret = sync_mapping_buffers(inode->i_mapping);
978 if (!(inode->i_state & I_DIRTY_ALL))
980 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
983 err = sync_inode_metadata(inode, 1);
991 EXPORT_SYMBOL(__generic_file_fsync);
994 * generic_file_fsync - generic fsync implementation for simple filesystems
996 * @file: file to synchronize
997 * @start: start offset in bytes
998 * @end: end offset in bytes (inclusive)
999 * @datasync: only synchronize essential metadata if true
1003 int generic_file_fsync(struct file *file, loff_t start, loff_t end,
1006 struct inode *inode = file->f_mapping->host;
1009 err = __generic_file_fsync(file, start, end, datasync);
1012 return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
1014 EXPORT_SYMBOL(generic_file_fsync);
1017 * generic_check_addressable - Check addressability of file system
1018 * @blocksize_bits: log of file system block size
1019 * @num_blocks: number of blocks in file system
1021 * Determine whether a file system with @num_blocks blocks (and a
1022 * block size of 2**@blocksize_bits) is addressable by the sector_t
1023 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
1025 int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
1027 u64 last_fs_block = num_blocks - 1;
1029 last_fs_block >> (PAGE_SHIFT - blocksize_bits);
1031 if (unlikely(num_blocks == 0))
1034 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
1037 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
1038 (last_fs_page > (pgoff_t)(~0ULL))) {
1043 EXPORT_SYMBOL(generic_check_addressable);
1046 * No-op implementation of ->fsync for in-memory filesystems.
1048 int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1052 EXPORT_SYMBOL(noop_fsync);
1054 /* Because kfree isn't assignment-compatible with void(void*) ;-/ */
1055 void kfree_link(void *p)
1059 EXPORT_SYMBOL(kfree_link);
1062 * nop .set_page_dirty method so that people can use .page_mkwrite on
1065 static int anon_set_page_dirty(struct page *page)
1071 * A single inode exists for all anon_inode files. Contrary to pipes,
1072 * anon_inode inodes have no associated per-instance data, so we need
1073 * only allocate one of them.
1075 struct inode *alloc_anon_inode(struct super_block *s)
1077 static const struct address_space_operations anon_aops = {
1078 .set_page_dirty = anon_set_page_dirty,
1080 struct inode *inode = new_inode_pseudo(s);
1083 return ERR_PTR(-ENOMEM);
1085 inode->i_ino = get_next_ino();
1086 inode->i_mapping->a_ops = &anon_aops;
1089 * Mark the inode dirty from the very beginning,
1090 * that way it will never be moved to the dirty
1091 * list because mark_inode_dirty() will think
1092 * that it already _is_ on the dirty list.
1094 inode->i_state = I_DIRTY;
1095 inode->i_mode = S_IRUSR | S_IWUSR;
1096 inode->i_uid = current_fsuid();
1097 inode->i_gid = current_fsgid();
1098 inode->i_flags |= S_PRIVATE;
1099 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
1102 EXPORT_SYMBOL(alloc_anon_inode);
1105 * simple_nosetlease - generic helper for prohibiting leases
1106 * @filp: file pointer
1107 * @arg: type of lease to obtain
1108 * @flp: new lease supplied for insertion
1109 * @priv: private data for lm_setup operation
1111 * Generic helper for filesystems that do not wish to allow leases to be set.
1112 * All arguments are ignored and it just returns -EINVAL.
1115 simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
1120 EXPORT_SYMBOL(simple_nosetlease);
1122 const char *simple_get_link(struct dentry *dentry, struct inode *inode,
1123 struct delayed_call *done)
1125 return inode->i_link;
1127 EXPORT_SYMBOL(simple_get_link);
1129 const struct inode_operations simple_symlink_inode_operations = {
1130 .get_link = simple_get_link,
1131 .readlink = generic_readlink
1133 EXPORT_SYMBOL(simple_symlink_inode_operations);
1136 * Operations for a permanently empty directory.
1138 static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
1140 return ERR_PTR(-ENOENT);
1143 static int empty_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
1146 struct inode *inode = d_inode(dentry);
1147 generic_fillattr(inode, stat);
1151 static int empty_dir_setattr(struct dentry *dentry, struct iattr *attr)
1156 static int empty_dir_setxattr(struct dentry *dentry, struct inode *inode,
1157 const char *name, const void *value,
1158 size_t size, int flags)
1163 static ssize_t empty_dir_getxattr(struct dentry *dentry, struct inode *inode,
1164 const char *name, void *value, size_t size)
1169 static int empty_dir_removexattr(struct dentry *dentry, const char *name)
1174 static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
1179 static const struct inode_operations empty_dir_inode_operations = {
1180 .lookup = empty_dir_lookup,
1181 .permission = generic_permission,
1182 .setattr = empty_dir_setattr,
1183 .getattr = empty_dir_getattr,
1184 .setxattr = empty_dir_setxattr,
1185 .getxattr = empty_dir_getxattr,
1186 .removexattr = empty_dir_removexattr,
1187 .listxattr = empty_dir_listxattr,
1190 static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
1192 /* An empty directory has two entries . and .. at offsets 0 and 1 */
1193 return generic_file_llseek_size(file, offset, whence, 2, 2);
1196 static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
1198 dir_emit_dots(file, ctx);
1202 static const struct file_operations empty_dir_operations = {
1203 .llseek = empty_dir_llseek,
1204 .read = generic_read_dir,
1205 .iterate_shared = empty_dir_readdir,
1206 .fsync = noop_fsync,
1210 void make_empty_dir_inode(struct inode *inode)
1212 set_nlink(inode, 2);
1213 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
1214 inode->i_uid = GLOBAL_ROOT_UID;
1215 inode->i_gid = GLOBAL_ROOT_GID;
1218 inode->i_blkbits = PAGE_SHIFT;
1219 inode->i_blocks = 0;
1221 inode->i_op = &empty_dir_inode_operations;
1222 inode->i_fop = &empty_dir_operations;
1225 bool is_empty_dir_inode(struct inode *inode)
1227 return (inode->i_fop == &empty_dir_operations) &&
1228 (inode->i_op == &empty_dir_inode_operations);