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 struct dentry *res = NULL;
95 spin_lock(&parent->d_lock);
96 for (p = from->next; p != &parent->d_subdirs; p = p->next) {
97 struct dentry *d = list_entry(p, struct dentry, d_child);
98 if (simple_positive(d) && !--count) {
103 spin_unlock(&parent->d_lock);
107 static void move_cursor(struct dentry *cursor, struct list_head *after)
109 struct dentry *parent = cursor->d_parent;
111 spin_lock(&parent->d_lock);
112 __list_del(cursor->d_child.prev, cursor->d_child.next);
114 list_add(&cursor->d_child, after);
116 list_add_tail(&cursor->d_child, &parent->d_subdirs);
117 spin_unlock(&parent->d_lock);
120 loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
122 struct dentry *dentry = file->f_path.dentry;
125 offset += file->f_pos;
132 if (offset != file->f_pos) {
133 file->f_pos = offset;
134 if (file->f_pos >= 2) {
135 struct dentry *cursor = file->private_data;
137 loff_t n = file->f_pos - 2;
139 inode_lock_shared(dentry->d_inode);
140 to = next_positive(dentry, &dentry->d_subdirs, n);
141 move_cursor(cursor, to ? &to->d_child : NULL);
142 inode_unlock_shared(dentry->d_inode);
147 EXPORT_SYMBOL(dcache_dir_lseek);
149 /* Relationship between i_mode and the DT_xxx types */
150 static inline unsigned char dt_type(struct inode *inode)
152 return (inode->i_mode >> 12) & 15;
156 * Directory is locked and all positive dentries in it are safe, since
157 * for ramfs-type trees they can't go away without unlink() or rmdir(),
158 * both impossible due to the lock on directory.
161 int dcache_readdir(struct file *file, struct dir_context *ctx)
163 struct dentry *dentry = file->f_path.dentry;
164 struct dentry *cursor = file->private_data;
165 struct list_head *p = &cursor->d_child;
169 if (!dir_emit_dots(file, ctx))
173 p = &dentry->d_subdirs;
174 while ((next = next_positive(dentry, p, 1)) != NULL) {
175 if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
176 d_inode(next)->i_ino, dt_type(d_inode(next))))
183 move_cursor(cursor, p);
186 EXPORT_SYMBOL(dcache_readdir);
188 ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
192 EXPORT_SYMBOL(generic_read_dir);
194 const struct file_operations simple_dir_operations = {
195 .open = dcache_dir_open,
196 .release = dcache_dir_close,
197 .llseek = dcache_dir_lseek,
198 .read = generic_read_dir,
199 .iterate_shared = dcache_readdir,
202 EXPORT_SYMBOL(simple_dir_operations);
204 const struct inode_operations simple_dir_inode_operations = {
205 .lookup = simple_lookup,
207 EXPORT_SYMBOL(simple_dir_inode_operations);
209 static const struct super_operations simple_super_operations = {
210 .statfs = simple_statfs,
214 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
215 * will never be mountable)
217 struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name,
218 const struct super_operations *ops,
219 const struct dentry_operations *dops, unsigned long magic)
221 struct super_block *s;
222 struct dentry *dentry;
224 struct qstr d_name = QSTR_INIT(name, strlen(name));
226 s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL);
230 s->s_maxbytes = MAX_LFS_FILESIZE;
231 s->s_blocksize = PAGE_SIZE;
232 s->s_blocksize_bits = PAGE_SHIFT;
234 s->s_op = ops ? ops : &simple_super_operations;
240 * since this is the first inode, make it number 1. New inodes created
241 * after this must take care not to collide with it (by passing
242 * max_reserved of 1 to iunique).
245 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
246 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
247 dentry = __d_alloc(s, &d_name);
252 d_instantiate(dentry, root);
255 s->s_flags |= MS_ACTIVE;
256 return dget(s->s_root);
259 deactivate_locked_super(s);
260 return ERR_PTR(-ENOMEM);
262 EXPORT_SYMBOL(mount_pseudo);
264 int simple_open(struct inode *inode, struct file *file)
266 if (inode->i_private)
267 file->private_data = inode->i_private;
270 EXPORT_SYMBOL(simple_open);
272 int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
274 struct inode *inode = d_inode(old_dentry);
276 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
280 d_instantiate(dentry, inode);
283 EXPORT_SYMBOL(simple_link);
285 int simple_empty(struct dentry *dentry)
287 struct dentry *child;
290 spin_lock(&dentry->d_lock);
291 list_for_each_entry(child, &dentry->d_subdirs, d_child) {
292 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
293 if (simple_positive(child)) {
294 spin_unlock(&child->d_lock);
297 spin_unlock(&child->d_lock);
301 spin_unlock(&dentry->d_lock);
304 EXPORT_SYMBOL(simple_empty);
306 int simple_unlink(struct inode *dir, struct dentry *dentry)
308 struct inode *inode = d_inode(dentry);
310 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
315 EXPORT_SYMBOL(simple_unlink);
317 int simple_rmdir(struct inode *dir, struct dentry *dentry)
319 if (!simple_empty(dentry))
322 drop_nlink(d_inode(dentry));
323 simple_unlink(dir, dentry);
327 EXPORT_SYMBOL(simple_rmdir);
329 int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
330 struct inode *new_dir, struct dentry *new_dentry)
332 struct inode *inode = d_inode(old_dentry);
333 int they_are_dirs = d_is_dir(old_dentry);
335 if (!simple_empty(new_dentry))
338 if (d_really_is_positive(new_dentry)) {
339 simple_unlink(new_dir, new_dentry);
341 drop_nlink(d_inode(new_dentry));
344 } else if (they_are_dirs) {
349 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
350 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
354 EXPORT_SYMBOL(simple_rename);
357 * simple_setattr - setattr for simple filesystem
359 * @iattr: iattr structure
361 * Returns 0 on success, -error on failure.
363 * simple_setattr is a simple ->setattr implementation without a proper
364 * implementation of size changes.
366 * It can either be used for in-memory filesystems or special files
367 * on simple regular filesystems. Anything that needs to change on-disk
368 * or wire state on size changes needs its own setattr method.
370 int simple_setattr(struct dentry *dentry, struct iattr *iattr)
372 struct inode *inode = d_inode(dentry);
375 error = inode_change_ok(inode, iattr);
379 if (iattr->ia_valid & ATTR_SIZE)
380 truncate_setsize(inode, iattr->ia_size);
381 setattr_copy(inode, iattr);
382 mark_inode_dirty(inode);
385 EXPORT_SYMBOL(simple_setattr);
387 int simple_readpage(struct file *file, struct page *page)
389 clear_highpage(page);
390 flush_dcache_page(page);
391 SetPageUptodate(page);
395 EXPORT_SYMBOL(simple_readpage);
397 int simple_write_begin(struct file *file, struct address_space *mapping,
398 loff_t pos, unsigned len, unsigned flags,
399 struct page **pagep, void **fsdata)
404 index = pos >> PAGE_SHIFT;
406 page = grab_cache_page_write_begin(mapping, index, flags);
412 if (!PageUptodate(page) && (len != PAGE_SIZE)) {
413 unsigned from = pos & (PAGE_SIZE - 1);
415 zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
419 EXPORT_SYMBOL(simple_write_begin);
422 * simple_write_end - .write_end helper for non-block-device FSes
423 * @available: See .write_end of address_space_operations
432 * simple_write_end does the minimum needed for updating a page after writing is
433 * done. It has the same API signature as the .write_end of
434 * address_space_operations vector. So it can just be set onto .write_end for
435 * FSes that don't need any other processing. i_mutex is assumed to be held.
436 * Block based filesystems should use generic_write_end().
437 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
438 * is not called, so a filesystem that actually does store data in .write_inode
439 * should extend on what's done here with a call to mark_inode_dirty() in the
440 * case that i_size has changed.
442 int simple_write_end(struct file *file, struct address_space *mapping,
443 loff_t pos, unsigned len, unsigned copied,
444 struct page *page, void *fsdata)
446 struct inode *inode = page->mapping->host;
447 loff_t last_pos = pos + copied;
449 /* zero the stale part of the page if we did a short copy */
451 unsigned from = pos & (PAGE_SIZE - 1);
453 zero_user(page, from + copied, len - copied);
456 if (!PageUptodate(page))
457 SetPageUptodate(page);
459 * No need to use i_size_read() here, the i_size
460 * cannot change under us because we hold the i_mutex.
462 if (last_pos > inode->i_size)
463 i_size_write(inode, last_pos);
465 set_page_dirty(page);
471 EXPORT_SYMBOL(simple_write_end);
474 * the inodes created here are not hashed. If you use iunique to generate
475 * unique inode values later for this filesystem, then you must take care
476 * to pass it an appropriate max_reserved value to avoid collisions.
478 int simple_fill_super(struct super_block *s, unsigned long magic,
479 struct tree_descr *files)
483 struct dentry *dentry;
486 s->s_blocksize = PAGE_SIZE;
487 s->s_blocksize_bits = PAGE_SHIFT;
489 s->s_op = &simple_super_operations;
492 inode = new_inode(s);
496 * because the root inode is 1, the files array must not contain an
500 inode->i_mode = S_IFDIR | 0755;
501 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
502 inode->i_op = &simple_dir_inode_operations;
503 inode->i_fop = &simple_dir_operations;
505 root = d_make_root(inode);
508 for (i = 0; !files->name || files->name[0]; i++, files++) {
512 /* warn if it tries to conflict with the root inode */
513 if (unlikely(i == 1))
514 printk(KERN_WARNING "%s: %s passed in a files array"
515 "with an index of 1!\n", __func__,
518 dentry = d_alloc_name(root, files->name);
521 inode = new_inode(s);
526 inode->i_mode = S_IFREG | files->mode;
527 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
528 inode->i_fop = files->ops;
530 d_add(dentry, inode);
536 shrink_dcache_parent(root);
540 EXPORT_SYMBOL(simple_fill_super);
542 static DEFINE_SPINLOCK(pin_fs_lock);
544 int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
546 struct vfsmount *mnt = NULL;
547 spin_lock(&pin_fs_lock);
548 if (unlikely(!*mount)) {
549 spin_unlock(&pin_fs_lock);
550 mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, NULL);
553 spin_lock(&pin_fs_lock);
559 spin_unlock(&pin_fs_lock);
563 EXPORT_SYMBOL(simple_pin_fs);
565 void simple_release_fs(struct vfsmount **mount, int *count)
567 struct vfsmount *mnt;
568 spin_lock(&pin_fs_lock);
572 spin_unlock(&pin_fs_lock);
575 EXPORT_SYMBOL(simple_release_fs);
578 * simple_read_from_buffer - copy data from the buffer to user space
579 * @to: the user space buffer to read to
580 * @count: the maximum number of bytes to read
581 * @ppos: the current position in the buffer
582 * @from: the buffer to read from
583 * @available: the size of the buffer
585 * The simple_read_from_buffer() function reads up to @count bytes from the
586 * buffer @from at offset @ppos into the user space address starting at @to.
588 * On success, the number of bytes read is returned and the offset @ppos is
589 * advanced by this number, or negative value is returned on error.
591 ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
592 const void *from, size_t available)
599 if (pos >= available || !count)
601 if (count > available - pos)
602 count = available - pos;
603 ret = copy_to_user(to, from + pos, count);
610 EXPORT_SYMBOL(simple_read_from_buffer);
613 * simple_write_to_buffer - copy data from user space to the buffer
614 * @to: the buffer to write to
615 * @available: the size of the buffer
616 * @ppos: the current position in the buffer
617 * @from: the user space buffer to read from
618 * @count: the maximum number of bytes to read
620 * The simple_write_to_buffer() function reads up to @count bytes from the user
621 * space address starting at @from into the buffer @to at offset @ppos.
623 * On success, the number of bytes written is returned and the offset @ppos is
624 * advanced by this number, or negative value is returned on error.
626 ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
627 const void __user *from, size_t count)
634 if (pos >= available || !count)
636 if (count > available - pos)
637 count = available - pos;
638 res = copy_from_user(to + pos, from, count);
645 EXPORT_SYMBOL(simple_write_to_buffer);
648 * memory_read_from_buffer - copy data from the buffer
649 * @to: the kernel space buffer to read to
650 * @count: the maximum number of bytes to read
651 * @ppos: the current position in the buffer
652 * @from: the buffer to read from
653 * @available: the size of the buffer
655 * The memory_read_from_buffer() function reads up to @count bytes from the
656 * buffer @from at offset @ppos into the kernel space address starting at @to.
658 * On success, the number of bytes read is returned and the offset @ppos is
659 * advanced by this number, or negative value is returned on error.
661 ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
662 const void *from, size_t available)
668 if (pos >= available)
670 if (count > available - pos)
671 count = available - pos;
672 memcpy(to, from + pos, count);
677 EXPORT_SYMBOL(memory_read_from_buffer);
680 * Transaction based IO.
681 * The file expects a single write which triggers the transaction, and then
682 * possibly a read which collects the result - which is stored in a
686 void simple_transaction_set(struct file *file, size_t n)
688 struct simple_transaction_argresp *ar = file->private_data;
690 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
693 * The barrier ensures that ar->size will really remain zero until
694 * ar->data is ready for reading.
699 EXPORT_SYMBOL(simple_transaction_set);
701 char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
703 struct simple_transaction_argresp *ar;
704 static DEFINE_SPINLOCK(simple_transaction_lock);
706 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
707 return ERR_PTR(-EFBIG);
709 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
711 return ERR_PTR(-ENOMEM);
713 spin_lock(&simple_transaction_lock);
715 /* only one write allowed per open */
716 if (file->private_data) {
717 spin_unlock(&simple_transaction_lock);
718 free_page((unsigned long)ar);
719 return ERR_PTR(-EBUSY);
722 file->private_data = ar;
724 spin_unlock(&simple_transaction_lock);
726 if (copy_from_user(ar->data, buf, size))
727 return ERR_PTR(-EFAULT);
731 EXPORT_SYMBOL(simple_transaction_get);
733 ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
735 struct simple_transaction_argresp *ar = file->private_data;
739 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
741 EXPORT_SYMBOL(simple_transaction_read);
743 int simple_transaction_release(struct inode *inode, struct file *file)
745 free_page((unsigned long)file->private_data);
748 EXPORT_SYMBOL(simple_transaction_release);
750 /* Simple attribute files */
753 int (*get)(void *, u64 *);
754 int (*set)(void *, u64);
755 char get_buf[24]; /* enough to store a u64 and "\n\0" */
758 const char *fmt; /* format for read operation */
759 struct mutex mutex; /* protects access to these buffers */
762 /* simple_attr_open is called by an actual attribute open file operation
763 * to set the attribute specific access operations. */
764 int simple_attr_open(struct inode *inode, struct file *file,
765 int (*get)(void *, u64 *), int (*set)(void *, u64),
768 struct simple_attr *attr;
770 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
776 attr->data = inode->i_private;
778 mutex_init(&attr->mutex);
780 file->private_data = attr;
782 return nonseekable_open(inode, file);
784 EXPORT_SYMBOL_GPL(simple_attr_open);
786 int simple_attr_release(struct inode *inode, struct file *file)
788 kfree(file->private_data);
791 EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
793 /* read from the buffer that is filled with the get function */
794 ssize_t simple_attr_read(struct file *file, char __user *buf,
795 size_t len, loff_t *ppos)
797 struct simple_attr *attr;
801 attr = file->private_data;
806 ret = mutex_lock_interruptible(&attr->mutex);
810 if (*ppos) { /* continued read */
811 size = strlen(attr->get_buf);
812 } else { /* first read */
814 ret = attr->get(attr->data, &val);
818 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
819 attr->fmt, (unsigned long long)val);
822 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
824 mutex_unlock(&attr->mutex);
827 EXPORT_SYMBOL_GPL(simple_attr_read);
829 /* interpret the buffer as a number to call the set function with */
830 ssize_t simple_attr_write(struct file *file, const char __user *buf,
831 size_t len, loff_t *ppos)
833 struct simple_attr *attr;
838 attr = file->private_data;
842 ret = mutex_lock_interruptible(&attr->mutex);
847 size = min(sizeof(attr->set_buf) - 1, len);
848 if (copy_from_user(attr->set_buf, buf, size))
851 attr->set_buf[size] = '\0';
852 val = simple_strtoll(attr->set_buf, NULL, 0);
853 ret = attr->set(attr->data, val);
855 ret = len; /* on success, claim we got the whole input */
857 mutex_unlock(&attr->mutex);
860 EXPORT_SYMBOL_GPL(simple_attr_write);
863 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
864 * @sb: filesystem to do the file handle conversion on
865 * @fid: file handle to convert
866 * @fh_len: length of the file handle in bytes
867 * @fh_type: type of file handle
868 * @get_inode: filesystem callback to retrieve inode
870 * This function decodes @fid as long as it has one of the well-known
871 * Linux filehandle types and calls @get_inode on it to retrieve the
872 * inode for the object specified in the file handle.
874 struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
875 int fh_len, int fh_type, struct inode *(*get_inode)
876 (struct super_block *sb, u64 ino, u32 gen))
878 struct inode *inode = NULL;
884 case FILEID_INO32_GEN:
885 case FILEID_INO32_GEN_PARENT:
886 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
890 return d_obtain_alias(inode);
892 EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
895 * generic_fh_to_parent - generic helper for the fh_to_parent export operation
896 * @sb: filesystem to do the file handle conversion on
897 * @fid: file handle to convert
898 * @fh_len: length of the file handle in bytes
899 * @fh_type: type of file handle
900 * @get_inode: filesystem callback to retrieve inode
902 * This function decodes @fid as long as it has one of the well-known
903 * Linux filehandle types and calls @get_inode on it to retrieve the
904 * inode for the _parent_ object specified in the file handle if it
905 * is specified in the file handle, or NULL otherwise.
907 struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
908 int fh_len, int fh_type, struct inode *(*get_inode)
909 (struct super_block *sb, u64 ino, u32 gen))
911 struct inode *inode = NULL;
917 case FILEID_INO32_GEN_PARENT:
918 inode = get_inode(sb, fid->i32.parent_ino,
919 (fh_len > 3 ? fid->i32.parent_gen : 0));
923 return d_obtain_alias(inode);
925 EXPORT_SYMBOL_GPL(generic_fh_to_parent);
928 * __generic_file_fsync - generic fsync implementation for simple filesystems
930 * @file: file to synchronize
931 * @start: start offset in bytes
932 * @end: end offset in bytes (inclusive)
933 * @datasync: only synchronize essential metadata if true
935 * This is a generic implementation of the fsync method for simple
936 * filesystems which track all non-inode metadata in the buffers list
937 * hanging off the address_space structure.
939 int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
942 struct inode *inode = file->f_mapping->host;
946 err = filemap_write_and_wait_range(inode->i_mapping, start, end);
951 ret = sync_mapping_buffers(inode->i_mapping);
952 if (!(inode->i_state & I_DIRTY_ALL))
954 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
957 err = sync_inode_metadata(inode, 1);
965 EXPORT_SYMBOL(__generic_file_fsync);
968 * generic_file_fsync - generic fsync implementation for simple filesystems
970 * @file: file to synchronize
971 * @start: start offset in bytes
972 * @end: end offset in bytes (inclusive)
973 * @datasync: only synchronize essential metadata if true
977 int generic_file_fsync(struct file *file, loff_t start, loff_t end,
980 struct inode *inode = file->f_mapping->host;
983 err = __generic_file_fsync(file, start, end, datasync);
986 return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
988 EXPORT_SYMBOL(generic_file_fsync);
991 * generic_check_addressable - Check addressability of file system
992 * @blocksize_bits: log of file system block size
993 * @num_blocks: number of blocks in file system
995 * Determine whether a file system with @num_blocks blocks (and a
996 * block size of 2**@blocksize_bits) is addressable by the sector_t
997 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
999 int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
1001 u64 last_fs_block = num_blocks - 1;
1003 last_fs_block >> (PAGE_SHIFT - blocksize_bits);
1005 if (unlikely(num_blocks == 0))
1008 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
1011 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
1012 (last_fs_page > (pgoff_t)(~0ULL))) {
1017 EXPORT_SYMBOL(generic_check_addressable);
1020 * No-op implementation of ->fsync for in-memory filesystems.
1022 int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1026 EXPORT_SYMBOL(noop_fsync);
1028 /* Because kfree isn't assignment-compatible with void(void*) ;-/ */
1029 void kfree_link(void *p)
1033 EXPORT_SYMBOL(kfree_link);
1036 * nop .set_page_dirty method so that people can use .page_mkwrite on
1039 static int anon_set_page_dirty(struct page *page)
1045 * A single inode exists for all anon_inode files. Contrary to pipes,
1046 * anon_inode inodes have no associated per-instance data, so we need
1047 * only allocate one of them.
1049 struct inode *alloc_anon_inode(struct super_block *s)
1051 static const struct address_space_operations anon_aops = {
1052 .set_page_dirty = anon_set_page_dirty,
1054 struct inode *inode = new_inode_pseudo(s);
1057 return ERR_PTR(-ENOMEM);
1059 inode->i_ino = get_next_ino();
1060 inode->i_mapping->a_ops = &anon_aops;
1063 * Mark the inode dirty from the very beginning,
1064 * that way it will never be moved to the dirty
1065 * list because mark_inode_dirty() will think
1066 * that it already _is_ on the dirty list.
1068 inode->i_state = I_DIRTY;
1069 inode->i_mode = S_IRUSR | S_IWUSR;
1070 inode->i_uid = current_fsuid();
1071 inode->i_gid = current_fsgid();
1072 inode->i_flags |= S_PRIVATE;
1073 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1076 EXPORT_SYMBOL(alloc_anon_inode);
1079 * simple_nosetlease - generic helper for prohibiting leases
1080 * @filp: file pointer
1081 * @arg: type of lease to obtain
1082 * @flp: new lease supplied for insertion
1083 * @priv: private data for lm_setup operation
1085 * Generic helper for filesystems that do not wish to allow leases to be set.
1086 * All arguments are ignored and it just returns -EINVAL.
1089 simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
1094 EXPORT_SYMBOL(simple_nosetlease);
1096 const char *simple_get_link(struct dentry *dentry, struct inode *inode,
1097 struct delayed_call *done)
1099 return inode->i_link;
1101 EXPORT_SYMBOL(simple_get_link);
1103 const struct inode_operations simple_symlink_inode_operations = {
1104 .get_link = simple_get_link,
1105 .readlink = generic_readlink
1107 EXPORT_SYMBOL(simple_symlink_inode_operations);
1110 * Operations for a permanently empty directory.
1112 static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
1114 return ERR_PTR(-ENOENT);
1117 static int empty_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
1120 struct inode *inode = d_inode(dentry);
1121 generic_fillattr(inode, stat);
1125 static int empty_dir_setattr(struct dentry *dentry, struct iattr *attr)
1130 static int empty_dir_setxattr(struct dentry *dentry, struct inode *inode,
1131 const char *name, const void *value,
1132 size_t size, int flags)
1137 static ssize_t empty_dir_getxattr(struct dentry *dentry, struct inode *inode,
1138 const char *name, void *value, size_t size)
1143 static int empty_dir_removexattr(struct dentry *dentry, const char *name)
1148 static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
1153 static const struct inode_operations empty_dir_inode_operations = {
1154 .lookup = empty_dir_lookup,
1155 .permission = generic_permission,
1156 .setattr = empty_dir_setattr,
1157 .getattr = empty_dir_getattr,
1158 .setxattr = empty_dir_setxattr,
1159 .getxattr = empty_dir_getxattr,
1160 .removexattr = empty_dir_removexattr,
1161 .listxattr = empty_dir_listxattr,
1164 static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
1166 /* An empty directory has two entries . and .. at offsets 0 and 1 */
1167 return generic_file_llseek_size(file, offset, whence, 2, 2);
1170 static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
1172 dir_emit_dots(file, ctx);
1176 static const struct file_operations empty_dir_operations = {
1177 .llseek = empty_dir_llseek,
1178 .read = generic_read_dir,
1179 .iterate_shared = empty_dir_readdir,
1180 .fsync = noop_fsync,
1184 void make_empty_dir_inode(struct inode *inode)
1186 set_nlink(inode, 2);
1187 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
1188 inode->i_uid = GLOBAL_ROOT_UID;
1189 inode->i_gid = GLOBAL_ROOT_GID;
1192 inode->i_blkbits = PAGE_SHIFT;
1193 inode->i_blocks = 0;
1195 inode->i_op = &empty_dir_inode_operations;
1196 inode->i_fop = &empty_dir_operations;
1199 bool is_empty_dir_inode(struct inode *inode)
1201 return (inode->i_fop == &empty_dir_operations) &&
1202 (inode->i_op == &empty_dir_inode_operations);