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/cred.h>
11 #include <linux/mount.h>
12 #include <linux/vfs.h>
13 #include <linux/quotaops.h>
14 #include <linux/mutex.h>
15 #include <linux/namei.h>
16 #include <linux/exportfs.h>
17 #include <linux/writeback.h>
18 #include <linux/buffer_head.h> /* sync_mapping_buffers */
20 #include <linux/uaccess.h>
24 int simple_getattr(const struct path
*path
, struct kstat
*stat
,
25 u32 request_mask
, unsigned int query_flags
)
27 struct inode
*inode
= d_inode(path
->dentry
);
28 generic_fillattr(inode
, stat
);
29 stat
->blocks
= inode
->i_mapping
->nrpages
<< (PAGE_SHIFT
- 9);
32 EXPORT_SYMBOL(simple_getattr
);
34 int simple_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
36 buf
->f_type
= dentry
->d_sb
->s_magic
;
37 buf
->f_bsize
= PAGE_SIZE
;
38 buf
->f_namelen
= NAME_MAX
;
41 EXPORT_SYMBOL(simple_statfs
);
44 * Retaining negative dentries for an in-memory filesystem just wastes
45 * memory and lookup time: arrange for them to be deleted immediately.
47 int always_delete_dentry(const struct dentry
*dentry
)
51 EXPORT_SYMBOL(always_delete_dentry
);
53 const struct dentry_operations simple_dentry_operations
= {
54 .d_delete
= always_delete_dentry
,
56 EXPORT_SYMBOL(simple_dentry_operations
);
59 * Lookup the data. This is trivial - if the dentry didn't already
60 * exist, we know it is negative. Set d_op to delete negative dentries.
62 struct dentry
*simple_lookup(struct inode
*dir
, struct dentry
*dentry
, unsigned int flags
)
64 if (dentry
->d_name
.len
> NAME_MAX
)
65 return ERR_PTR(-ENAMETOOLONG
);
66 if (!dentry
->d_sb
->s_d_op
)
67 d_set_d_op(dentry
, &simple_dentry_operations
);
71 EXPORT_SYMBOL(simple_lookup
);
73 int dcache_dir_open(struct inode
*inode
, struct file
*file
)
75 file
->private_data
= d_alloc_cursor(file
->f_path
.dentry
);
77 return file
->private_data
? 0 : -ENOMEM
;
79 EXPORT_SYMBOL(dcache_dir_open
);
81 int dcache_dir_close(struct inode
*inode
, struct file
*file
)
83 dput(file
->private_data
);
86 EXPORT_SYMBOL(dcache_dir_close
);
88 /* parent is locked at least shared */
90 * Returns an element of siblings' list.
91 * We are looking for <count>th positive after <p>; if
92 * found, dentry is grabbed and passed to caller via *<res>.
93 * If no such element exists, the anchor of list is returned
94 * and *<res> is set to NULL.
96 static struct list_head
*scan_positives(struct dentry
*cursor
,
101 struct dentry
*dentry
= cursor
->d_parent
, *found
= NULL
;
103 spin_lock(&dentry
->d_lock
);
104 while ((p
= p
->next
) != &dentry
->d_subdirs
) {
105 struct dentry
*d
= list_entry(p
, struct dentry
, d_child
);
106 // we must at least skip cursors, to avoid livelocks
107 if (d
->d_flags
& DCACHE_DENTRY_CURSOR
)
109 if (simple_positive(d
) && !--count
) {
110 spin_lock_nested(&d
->d_lock
, DENTRY_D_LOCK_NESTED
);
111 if (simple_positive(d
))
112 found
= dget_dlock(d
);
113 spin_unlock(&d
->d_lock
);
118 if (need_resched()) {
119 list_move(&cursor
->d_child
, p
);
120 p
= &cursor
->d_child
;
121 spin_unlock(&dentry
->d_lock
);
123 spin_lock(&dentry
->d_lock
);
126 spin_unlock(&dentry
->d_lock
);
132 loff_t
dcache_dir_lseek(struct file
*file
, loff_t offset
, int whence
)
134 struct dentry
*dentry
= file
->f_path
.dentry
;
137 offset
+= file
->f_pos
;
144 if (offset
!= file
->f_pos
) {
145 struct dentry
*cursor
= file
->private_data
;
146 struct dentry
*to
= NULL
;
149 file
->f_pos
= offset
;
150 inode_lock_shared(dentry
->d_inode
);
152 if (file
->f_pos
> 2) {
153 p
= scan_positives(cursor
, &dentry
->d_subdirs
,
154 file
->f_pos
- 2, &to
);
155 spin_lock(&dentry
->d_lock
);
156 list_move(&cursor
->d_child
, p
);
157 spin_unlock(&dentry
->d_lock
);
159 spin_lock(&dentry
->d_lock
);
160 list_del_init(&cursor
->d_child
);
161 spin_unlock(&dentry
->d_lock
);
166 inode_unlock_shared(dentry
->d_inode
);
170 EXPORT_SYMBOL(dcache_dir_lseek
);
172 /* Relationship between i_mode and the DT_xxx types */
173 static inline unsigned char dt_type(struct inode
*inode
)
175 return (inode
->i_mode
>> 12) & 15;
179 * Directory is locked and all positive dentries in it are safe, since
180 * for ramfs-type trees they can't go away without unlink() or rmdir(),
181 * both impossible due to the lock on directory.
184 int dcache_readdir(struct file
*file
, struct dir_context
*ctx
)
186 struct dentry
*dentry
= file
->f_path
.dentry
;
187 struct dentry
*cursor
= file
->private_data
;
188 struct list_head
*anchor
= &dentry
->d_subdirs
;
189 struct dentry
*next
= NULL
;
192 if (!dir_emit_dots(file
, ctx
))
198 p
= &cursor
->d_child
;
200 while ((p
= scan_positives(cursor
, p
, 1, &next
)) != anchor
) {
201 if (!dir_emit(ctx
, next
->d_name
.name
, next
->d_name
.len
,
202 d_inode(next
)->i_ino
, dt_type(d_inode(next
))))
206 spin_lock(&dentry
->d_lock
);
207 list_move_tail(&cursor
->d_child
, p
);
208 spin_unlock(&dentry
->d_lock
);
213 EXPORT_SYMBOL(dcache_readdir
);
215 ssize_t
generic_read_dir(struct file
*filp
, char __user
*buf
, size_t siz
, loff_t
*ppos
)
219 EXPORT_SYMBOL(generic_read_dir
);
221 const struct file_operations simple_dir_operations
= {
222 .open
= dcache_dir_open
,
223 .release
= dcache_dir_close
,
224 .llseek
= dcache_dir_lseek
,
225 .read
= generic_read_dir
,
226 .iterate_shared
= dcache_readdir
,
229 EXPORT_SYMBOL(simple_dir_operations
);
231 const struct inode_operations simple_dir_inode_operations
= {
232 .lookup
= simple_lookup
,
234 EXPORT_SYMBOL(simple_dir_inode_operations
);
236 static const struct super_operations simple_super_operations
= {
237 .statfs
= simple_statfs
,
241 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
242 * will never be mountable)
244 struct dentry
*mount_pseudo_xattr(struct file_system_type
*fs_type
, char *name
,
245 const struct super_operations
*ops
, const struct xattr_handler
**xattr
,
246 const struct dentry_operations
*dops
, unsigned long magic
)
248 struct super_block
*s
;
249 struct dentry
*dentry
;
251 struct qstr d_name
= QSTR_INIT(name
, strlen(name
));
253 s
= sget_userns(fs_type
, NULL
, set_anon_super
, MS_KERNMOUNT
|MS_NOUSER
,
254 &init_user_ns
, NULL
);
258 s
->s_maxbytes
= MAX_LFS_FILESIZE
;
259 s
->s_blocksize
= PAGE_SIZE
;
260 s
->s_blocksize_bits
= PAGE_SHIFT
;
262 s
->s_op
= ops
? ops
: &simple_super_operations
;
269 * since this is the first inode, make it number 1. New inodes created
270 * after this must take care not to collide with it (by passing
271 * max_reserved of 1 to iunique).
274 root
->i_mode
= S_IFDIR
| S_IRUSR
| S_IWUSR
;
275 root
->i_atime
= root
->i_mtime
= root
->i_ctime
= current_time(root
);
276 dentry
= __d_alloc(s
, &d_name
);
281 d_instantiate(dentry
, root
);
284 s
->s_flags
|= MS_ACTIVE
;
285 return dget(s
->s_root
);
288 deactivate_locked_super(s
);
289 return ERR_PTR(-ENOMEM
);
291 EXPORT_SYMBOL(mount_pseudo_xattr
);
293 int simple_open(struct inode
*inode
, struct file
*file
)
295 if (inode
->i_private
)
296 file
->private_data
= inode
->i_private
;
299 EXPORT_SYMBOL(simple_open
);
301 int simple_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*dentry
)
303 struct inode
*inode
= d_inode(old_dentry
);
305 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= current_time(inode
);
309 d_instantiate(dentry
, inode
);
312 EXPORT_SYMBOL(simple_link
);
314 int simple_empty(struct dentry
*dentry
)
316 struct dentry
*child
;
319 spin_lock(&dentry
->d_lock
);
320 list_for_each_entry(child
, &dentry
->d_subdirs
, d_child
) {
321 spin_lock_nested(&child
->d_lock
, DENTRY_D_LOCK_NESTED
);
322 if (simple_positive(child
)) {
323 spin_unlock(&child
->d_lock
);
326 spin_unlock(&child
->d_lock
);
330 spin_unlock(&dentry
->d_lock
);
333 EXPORT_SYMBOL(simple_empty
);
335 int simple_unlink(struct inode
*dir
, struct dentry
*dentry
)
337 struct inode
*inode
= d_inode(dentry
);
339 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= current_time(inode
);
344 EXPORT_SYMBOL(simple_unlink
);
346 int simple_rmdir(struct inode
*dir
, struct dentry
*dentry
)
348 if (!simple_empty(dentry
))
351 drop_nlink(d_inode(dentry
));
352 simple_unlink(dir
, dentry
);
356 EXPORT_SYMBOL(simple_rmdir
);
358 int simple_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
359 struct inode
*new_dir
, struct dentry
*new_dentry
,
362 struct inode
*inode
= d_inode(old_dentry
);
363 int they_are_dirs
= d_is_dir(old_dentry
);
365 if (flags
& ~RENAME_NOREPLACE
)
368 if (!simple_empty(new_dentry
))
371 if (d_really_is_positive(new_dentry
)) {
372 simple_unlink(new_dir
, new_dentry
);
374 drop_nlink(d_inode(new_dentry
));
377 } else if (they_are_dirs
) {
382 old_dir
->i_ctime
= old_dir
->i_mtime
= new_dir
->i_ctime
=
383 new_dir
->i_mtime
= inode
->i_ctime
= current_time(old_dir
);
387 EXPORT_SYMBOL(simple_rename
);
390 * simple_setattr - setattr for simple filesystem
392 * @iattr: iattr structure
394 * Returns 0 on success, -error on failure.
396 * simple_setattr is a simple ->setattr implementation without a proper
397 * implementation of size changes.
399 * It can either be used for in-memory filesystems or special files
400 * on simple regular filesystems. Anything that needs to change on-disk
401 * or wire state on size changes needs its own setattr method.
403 int simple_setattr(struct dentry
*dentry
, struct iattr
*iattr
)
405 struct inode
*inode
= d_inode(dentry
);
408 error
= setattr_prepare(dentry
, iattr
);
412 if (iattr
->ia_valid
& ATTR_SIZE
)
413 truncate_setsize(inode
, iattr
->ia_size
);
414 setattr_copy(inode
, iattr
);
415 mark_inode_dirty(inode
);
418 EXPORT_SYMBOL(simple_setattr
);
420 int simple_readpage(struct file
*file
, struct page
*page
)
422 clear_highpage(page
);
423 flush_dcache_page(page
);
424 SetPageUptodate(page
);
428 EXPORT_SYMBOL(simple_readpage
);
430 int simple_write_begin(struct file
*file
, struct address_space
*mapping
,
431 loff_t pos
, unsigned len
, unsigned flags
,
432 struct page
**pagep
, void **fsdata
)
437 index
= pos
>> PAGE_SHIFT
;
439 page
= grab_cache_page_write_begin(mapping
, index
, flags
);
445 if (!PageUptodate(page
) && (len
!= PAGE_SIZE
)) {
446 unsigned from
= pos
& (PAGE_SIZE
- 1);
448 zero_user_segments(page
, 0, from
, from
+ len
, PAGE_SIZE
);
452 EXPORT_SYMBOL(simple_write_begin
);
455 * simple_write_end - .write_end helper for non-block-device FSes
456 * @available: See .write_end of address_space_operations
465 * simple_write_end does the minimum needed for updating a page after writing is
466 * done. It has the same API signature as the .write_end of
467 * address_space_operations vector. So it can just be set onto .write_end for
468 * FSes that don't need any other processing. i_mutex is assumed to be held.
469 * Block based filesystems should use generic_write_end().
470 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
471 * is not called, so a filesystem that actually does store data in .write_inode
472 * should extend on what's done here with a call to mark_inode_dirty() in the
473 * case that i_size has changed.
475 * Use *ONLY* with simple_readpage()
477 int simple_write_end(struct file
*file
, struct address_space
*mapping
,
478 loff_t pos
, unsigned len
, unsigned copied
,
479 struct page
*page
, void *fsdata
)
481 struct inode
*inode
= page
->mapping
->host
;
482 loff_t last_pos
= pos
+ copied
;
484 /* zero the stale part of the page if we did a short copy */
485 if (!PageUptodate(page
)) {
487 unsigned from
= pos
& (PAGE_SIZE
- 1);
489 zero_user(page
, from
+ copied
, len
- copied
);
491 SetPageUptodate(page
);
494 * No need to use i_size_read() here, the i_size
495 * cannot change under us because we hold the i_mutex.
497 if (last_pos
> inode
->i_size
)
498 i_size_write(inode
, last_pos
);
500 set_page_dirty(page
);
506 EXPORT_SYMBOL(simple_write_end
);
509 * the inodes created here are not hashed. If you use iunique to generate
510 * unique inode values later for this filesystem, then you must take care
511 * to pass it an appropriate max_reserved value to avoid collisions.
513 int simple_fill_super(struct super_block
*s
, unsigned long magic
,
514 const struct tree_descr
*files
)
518 struct dentry
*dentry
;
521 s
->s_blocksize
= PAGE_SIZE
;
522 s
->s_blocksize_bits
= PAGE_SHIFT
;
524 s
->s_op
= &simple_super_operations
;
527 inode
= new_inode(s
);
531 * because the root inode is 1, the files array must not contain an
535 inode
->i_mode
= S_IFDIR
| 0755;
536 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= current_time(inode
);
537 inode
->i_op
= &simple_dir_inode_operations
;
538 inode
->i_fop
= &simple_dir_operations
;
540 root
= d_make_root(inode
);
543 for (i
= 0; !files
->name
|| files
->name
[0]; i
++, files
++) {
547 /* warn if it tries to conflict with the root inode */
548 if (unlikely(i
== 1))
549 printk(KERN_WARNING
"%s: %s passed in a files array"
550 "with an index of 1!\n", __func__
,
553 dentry
= d_alloc_name(root
, files
->name
);
556 inode
= new_inode(s
);
561 inode
->i_mode
= S_IFREG
| files
->mode
;
562 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= current_time(inode
);
563 inode
->i_fop
= files
->ops
;
565 d_add(dentry
, inode
);
571 shrink_dcache_parent(root
);
575 EXPORT_SYMBOL(simple_fill_super
);
577 static DEFINE_SPINLOCK(pin_fs_lock
);
579 int simple_pin_fs(struct file_system_type
*type
, struct vfsmount
**mount
, int *count
)
581 struct vfsmount
*mnt
= NULL
;
582 spin_lock(&pin_fs_lock
);
583 if (unlikely(!*mount
)) {
584 spin_unlock(&pin_fs_lock
);
585 mnt
= vfs_kern_mount(type
, MS_KERNMOUNT
, type
->name
, NULL
);
588 spin_lock(&pin_fs_lock
);
594 spin_unlock(&pin_fs_lock
);
598 EXPORT_SYMBOL(simple_pin_fs
);
600 void simple_release_fs(struct vfsmount
**mount
, int *count
)
602 struct vfsmount
*mnt
;
603 spin_lock(&pin_fs_lock
);
607 spin_unlock(&pin_fs_lock
);
610 EXPORT_SYMBOL(simple_release_fs
);
613 * simple_read_from_buffer - copy data from the buffer to user space
614 * @to: the user space buffer to read to
615 * @count: the maximum number of bytes to read
616 * @ppos: the current position in the buffer
617 * @from: the buffer to read from
618 * @available: the size of the buffer
620 * The simple_read_from_buffer() function reads up to @count bytes from the
621 * buffer @from at offset @ppos into the user space address starting at @to.
623 * On success, the number of bytes read is returned and the offset @ppos is
624 * advanced by this number, or negative value is returned on error.
626 ssize_t
simple_read_from_buffer(void __user
*to
, size_t count
, loff_t
*ppos
,
627 const void *from
, size_t available
)
634 if (pos
>= available
|| !count
)
636 if (count
> available
- pos
)
637 count
= available
- pos
;
638 ret
= copy_to_user(to
, from
+ pos
, count
);
645 EXPORT_SYMBOL(simple_read_from_buffer
);
648 * simple_write_to_buffer - copy data from user space to the buffer
649 * @to: the buffer to write to
650 * @available: the size of the buffer
651 * @ppos: the current position in the buffer
652 * @from: the user space buffer to read from
653 * @count: the maximum number of bytes to read
655 * The simple_write_to_buffer() function reads up to @count bytes from the user
656 * space address starting at @from into the buffer @to at offset @ppos.
658 * On success, the number of bytes written is returned and the offset @ppos is
659 * advanced by this number, or negative value is returned on error.
661 ssize_t
simple_write_to_buffer(void *to
, size_t available
, loff_t
*ppos
,
662 const void __user
*from
, size_t count
)
669 if (pos
>= available
|| !count
)
671 if (count
> available
- pos
)
672 count
= available
- pos
;
673 res
= copy_from_user(to
+ pos
, from
, count
);
680 EXPORT_SYMBOL(simple_write_to_buffer
);
683 * memory_read_from_buffer - copy data from the buffer
684 * @to: the kernel space buffer to read to
685 * @count: the maximum number of bytes to read
686 * @ppos: the current position in the buffer
687 * @from: the buffer to read from
688 * @available: the size of the buffer
690 * The memory_read_from_buffer() function reads up to @count bytes from the
691 * buffer @from at offset @ppos into the kernel space address starting at @to.
693 * On success, the number of bytes read is returned and the offset @ppos is
694 * advanced by this number, or negative value is returned on error.
696 ssize_t
memory_read_from_buffer(void *to
, size_t count
, loff_t
*ppos
,
697 const void *from
, size_t available
)
703 if (pos
>= available
)
705 if (count
> available
- pos
)
706 count
= available
- pos
;
707 memcpy(to
, from
+ pos
, count
);
712 EXPORT_SYMBOL(memory_read_from_buffer
);
715 * Transaction based IO.
716 * The file expects a single write which triggers the transaction, and then
717 * possibly a read which collects the result - which is stored in a
721 void simple_transaction_set(struct file
*file
, size_t n
)
723 struct simple_transaction_argresp
*ar
= file
->private_data
;
725 BUG_ON(n
> SIMPLE_TRANSACTION_LIMIT
);
728 * The barrier ensures that ar->size will really remain zero until
729 * ar->data is ready for reading.
734 EXPORT_SYMBOL(simple_transaction_set
);
736 char *simple_transaction_get(struct file
*file
, const char __user
*buf
, size_t size
)
738 struct simple_transaction_argresp
*ar
;
739 static DEFINE_SPINLOCK(simple_transaction_lock
);
741 if (size
> SIMPLE_TRANSACTION_LIMIT
- 1)
742 return ERR_PTR(-EFBIG
);
744 ar
= (struct simple_transaction_argresp
*)get_zeroed_page(GFP_KERNEL
);
746 return ERR_PTR(-ENOMEM
);
748 spin_lock(&simple_transaction_lock
);
750 /* only one write allowed per open */
751 if (file
->private_data
) {
752 spin_unlock(&simple_transaction_lock
);
753 free_page((unsigned long)ar
);
754 return ERR_PTR(-EBUSY
);
757 file
->private_data
= ar
;
759 spin_unlock(&simple_transaction_lock
);
761 if (copy_from_user(ar
->data
, buf
, size
))
762 return ERR_PTR(-EFAULT
);
766 EXPORT_SYMBOL(simple_transaction_get
);
768 ssize_t
simple_transaction_read(struct file
*file
, char __user
*buf
, size_t size
, loff_t
*pos
)
770 struct simple_transaction_argresp
*ar
= file
->private_data
;
774 return simple_read_from_buffer(buf
, size
, pos
, ar
->data
, ar
->size
);
776 EXPORT_SYMBOL(simple_transaction_read
);
778 int simple_transaction_release(struct inode
*inode
, struct file
*file
)
780 free_page((unsigned long)file
->private_data
);
783 EXPORT_SYMBOL(simple_transaction_release
);
785 /* Simple attribute files */
788 int (*get
)(void *, u64
*);
789 int (*set
)(void *, u64
);
790 char get_buf
[24]; /* enough to store a u64 and "\n\0" */
793 const char *fmt
; /* format for read operation */
794 struct mutex mutex
; /* protects access to these buffers */
797 /* simple_attr_open is called by an actual attribute open file operation
798 * to set the attribute specific access operations. */
799 int simple_attr_open(struct inode
*inode
, struct file
*file
,
800 int (*get
)(void *, u64
*), int (*set
)(void *, u64
),
803 struct simple_attr
*attr
;
805 attr
= kzalloc(sizeof(*attr
), GFP_KERNEL
);
811 attr
->data
= inode
->i_private
;
813 mutex_init(&attr
->mutex
);
815 file
->private_data
= attr
;
817 return nonseekable_open(inode
, file
);
819 EXPORT_SYMBOL_GPL(simple_attr_open
);
821 int simple_attr_release(struct inode
*inode
, struct file
*file
)
823 kfree(file
->private_data
);
826 EXPORT_SYMBOL_GPL(simple_attr_release
); /* GPL-only? This? Really? */
828 /* read from the buffer that is filled with the get function */
829 ssize_t
simple_attr_read(struct file
*file
, char __user
*buf
,
830 size_t len
, loff_t
*ppos
)
832 struct simple_attr
*attr
;
836 attr
= file
->private_data
;
841 ret
= mutex_lock_interruptible(&attr
->mutex
);
845 if (*ppos
&& attr
->get_buf
[0]) {
847 size
= strlen(attr
->get_buf
);
851 ret
= attr
->get(attr
->data
, &val
);
855 size
= scnprintf(attr
->get_buf
, sizeof(attr
->get_buf
),
856 attr
->fmt
, (unsigned long long)val
);
859 ret
= simple_read_from_buffer(buf
, len
, ppos
, attr
->get_buf
, size
);
861 mutex_unlock(&attr
->mutex
);
864 EXPORT_SYMBOL_GPL(simple_attr_read
);
866 /* interpret the buffer as a number to call the set function with */
867 ssize_t
simple_attr_write(struct file
*file
, const char __user
*buf
,
868 size_t len
, loff_t
*ppos
)
870 struct simple_attr
*attr
;
875 attr
= file
->private_data
;
879 ret
= mutex_lock_interruptible(&attr
->mutex
);
884 size
= min(sizeof(attr
->set_buf
) - 1, len
);
885 if (copy_from_user(attr
->set_buf
, buf
, size
))
888 attr
->set_buf
[size
] = '\0';
889 val
= simple_strtoll(attr
->set_buf
, NULL
, 0);
890 ret
= attr
->set(attr
->data
, val
);
892 ret
= len
; /* on success, claim we got the whole input */
894 mutex_unlock(&attr
->mutex
);
897 EXPORT_SYMBOL_GPL(simple_attr_write
);
900 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
901 * @sb: filesystem to do the file handle conversion on
902 * @fid: file handle to convert
903 * @fh_len: length of the file handle in bytes
904 * @fh_type: type of file handle
905 * @get_inode: filesystem callback to retrieve inode
907 * This function decodes @fid as long as it has one of the well-known
908 * Linux filehandle types and calls @get_inode on it to retrieve the
909 * inode for the object specified in the file handle.
911 struct dentry
*generic_fh_to_dentry(struct super_block
*sb
, struct fid
*fid
,
912 int fh_len
, int fh_type
, struct inode
*(*get_inode
)
913 (struct super_block
*sb
, u64 ino
, u32 gen
))
915 struct inode
*inode
= NULL
;
921 case FILEID_INO32_GEN
:
922 case FILEID_INO32_GEN_PARENT
:
923 inode
= get_inode(sb
, fid
->i32
.ino
, fid
->i32
.gen
);
927 return d_obtain_alias(inode
);
929 EXPORT_SYMBOL_GPL(generic_fh_to_dentry
);
932 * generic_fh_to_parent - generic helper for the fh_to_parent export operation
933 * @sb: filesystem to do the file handle conversion on
934 * @fid: file handle to convert
935 * @fh_len: length of the file handle in bytes
936 * @fh_type: type of file handle
937 * @get_inode: filesystem callback to retrieve inode
939 * This function decodes @fid as long as it has one of the well-known
940 * Linux filehandle types and calls @get_inode on it to retrieve the
941 * inode for the _parent_ object specified in the file handle if it
942 * is specified in the file handle, or NULL otherwise.
944 struct dentry
*generic_fh_to_parent(struct super_block
*sb
, struct fid
*fid
,
945 int fh_len
, int fh_type
, struct inode
*(*get_inode
)
946 (struct super_block
*sb
, u64 ino
, u32 gen
))
948 struct inode
*inode
= NULL
;
954 case FILEID_INO32_GEN_PARENT
:
955 inode
= get_inode(sb
, fid
->i32
.parent_ino
,
956 (fh_len
> 3 ? fid
->i32
.parent_gen
: 0));
960 return d_obtain_alias(inode
);
962 EXPORT_SYMBOL_GPL(generic_fh_to_parent
);
965 * __generic_file_fsync - generic fsync implementation for simple filesystems
967 * @file: file to synchronize
968 * @start: start offset in bytes
969 * @end: end offset in bytes (inclusive)
970 * @datasync: only synchronize essential metadata if true
972 * This is a generic implementation of the fsync method for simple
973 * filesystems which track all non-inode metadata in the buffers list
974 * hanging off the address_space structure.
976 int __generic_file_fsync(struct file
*file
, loff_t start
, loff_t end
,
979 struct inode
*inode
= file
->f_mapping
->host
;
983 err
= file_write_and_wait_range(file
, start
, end
);
988 ret
= sync_mapping_buffers(inode
->i_mapping
);
989 if (!(inode
->i_state
& I_DIRTY_ALL
))
991 if (datasync
&& !(inode
->i_state
& I_DIRTY_DATASYNC
))
994 err
= sync_inode_metadata(inode
, 1);
1000 /* check and advance again to catch errors after syncing out buffers */
1001 err
= file_check_and_advance_wb_err(file
);
1006 EXPORT_SYMBOL(__generic_file_fsync
);
1009 * generic_file_fsync - generic fsync implementation for simple filesystems
1011 * @file: file to synchronize
1012 * @start: start offset in bytes
1013 * @end: end offset in bytes (inclusive)
1014 * @datasync: only synchronize essential metadata if true
1018 int generic_file_fsync(struct file
*file
, loff_t start
, loff_t end
,
1021 struct inode
*inode
= file
->f_mapping
->host
;
1024 err
= __generic_file_fsync(file
, start
, end
, datasync
);
1027 return blkdev_issue_flush(inode
->i_sb
->s_bdev
, GFP_KERNEL
, NULL
);
1029 EXPORT_SYMBOL(generic_file_fsync
);
1032 * generic_check_addressable - Check addressability of file system
1033 * @blocksize_bits: log of file system block size
1034 * @num_blocks: number of blocks in file system
1036 * Determine whether a file system with @num_blocks blocks (and a
1037 * block size of 2**@blocksize_bits) is addressable by the sector_t
1038 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
1040 int generic_check_addressable(unsigned blocksize_bits
, u64 num_blocks
)
1042 u64 last_fs_block
= num_blocks
- 1;
1044 last_fs_block
>> (PAGE_SHIFT
- blocksize_bits
);
1046 if (unlikely(num_blocks
== 0))
1049 if ((blocksize_bits
< 9) || (blocksize_bits
> PAGE_SHIFT
))
1052 if ((last_fs_block
> (sector_t
)(~0ULL) >> (blocksize_bits
- 9)) ||
1053 (last_fs_page
> (pgoff_t
)(~0ULL))) {
1058 EXPORT_SYMBOL(generic_check_addressable
);
1061 * No-op implementation of ->fsync for in-memory filesystems.
1063 int noop_fsync(struct file
*file
, loff_t start
, loff_t end
, int datasync
)
1067 EXPORT_SYMBOL(noop_fsync
);
1069 /* Because kfree isn't assignment-compatible with void(void*) ;-/ */
1070 void kfree_link(void *p
)
1074 EXPORT_SYMBOL(kfree_link
);
1077 * nop .set_page_dirty method so that people can use .page_mkwrite on
1080 static int anon_set_page_dirty(struct page
*page
)
1086 * A single inode exists for all anon_inode files. Contrary to pipes,
1087 * anon_inode inodes have no associated per-instance data, so we need
1088 * only allocate one of them.
1090 struct inode
*alloc_anon_inode(struct super_block
*s
)
1092 static const struct address_space_operations anon_aops
= {
1093 .set_page_dirty
= anon_set_page_dirty
,
1095 struct inode
*inode
= new_inode_pseudo(s
);
1098 return ERR_PTR(-ENOMEM
);
1100 inode
->i_ino
= get_next_ino();
1101 inode
->i_mapping
->a_ops
= &anon_aops
;
1104 * Mark the inode dirty from the very beginning,
1105 * that way it will never be moved to the dirty
1106 * list because mark_inode_dirty() will think
1107 * that it already _is_ on the dirty list.
1109 inode
->i_state
= I_DIRTY
;
1110 inode
->i_mode
= S_IRUSR
| S_IWUSR
;
1111 inode
->i_uid
= current_fsuid();
1112 inode
->i_gid
= current_fsgid();
1113 inode
->i_flags
|= S_PRIVATE
;
1114 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= current_time(inode
);
1117 EXPORT_SYMBOL(alloc_anon_inode
);
1120 * simple_nosetlease - generic helper for prohibiting leases
1121 * @filp: file pointer
1122 * @arg: type of lease to obtain
1123 * @flp: new lease supplied for insertion
1124 * @priv: private data for lm_setup operation
1126 * Generic helper for filesystems that do not wish to allow leases to be set.
1127 * All arguments are ignored and it just returns -EINVAL.
1130 simple_nosetlease(struct file
*filp
, long arg
, struct file_lock
**flp
,
1135 EXPORT_SYMBOL(simple_nosetlease
);
1137 const char *simple_get_link(struct dentry
*dentry
, struct inode
*inode
,
1138 struct delayed_call
*done
)
1140 return inode
->i_link
;
1142 EXPORT_SYMBOL(simple_get_link
);
1144 const struct inode_operations simple_symlink_inode_operations
= {
1145 .get_link
= simple_get_link
,
1147 EXPORT_SYMBOL(simple_symlink_inode_operations
);
1150 * Operations for a permanently empty directory.
1152 static struct dentry
*empty_dir_lookup(struct inode
*dir
, struct dentry
*dentry
, unsigned int flags
)
1154 return ERR_PTR(-ENOENT
);
1157 static int empty_dir_getattr(const struct path
*path
, struct kstat
*stat
,
1158 u32 request_mask
, unsigned int query_flags
)
1160 struct inode
*inode
= d_inode(path
->dentry
);
1161 generic_fillattr(inode
, stat
);
1165 static int empty_dir_setattr(struct dentry
*dentry
, struct iattr
*attr
)
1170 static ssize_t
empty_dir_listxattr(struct dentry
*dentry
, char *list
, size_t size
)
1175 static const struct inode_operations empty_dir_inode_operations
= {
1176 .lookup
= empty_dir_lookup
,
1177 .permission
= generic_permission
,
1178 .setattr
= empty_dir_setattr
,
1179 .getattr
= empty_dir_getattr
,
1180 .listxattr
= empty_dir_listxattr
,
1183 static loff_t
empty_dir_llseek(struct file
*file
, loff_t offset
, int whence
)
1185 /* An empty directory has two entries . and .. at offsets 0 and 1 */
1186 return generic_file_llseek_size(file
, offset
, whence
, 2, 2);
1189 static int empty_dir_readdir(struct file
*file
, struct dir_context
*ctx
)
1191 dir_emit_dots(file
, ctx
);
1195 static const struct file_operations empty_dir_operations
= {
1196 .llseek
= empty_dir_llseek
,
1197 .read
= generic_read_dir
,
1198 .iterate_shared
= empty_dir_readdir
,
1199 .fsync
= noop_fsync
,
1203 void make_empty_dir_inode(struct inode
*inode
)
1205 set_nlink(inode
, 2);
1206 inode
->i_mode
= S_IFDIR
| S_IRUGO
| S_IXUGO
;
1207 inode
->i_uid
= GLOBAL_ROOT_UID
;
1208 inode
->i_gid
= GLOBAL_ROOT_GID
;
1211 inode
->i_blkbits
= PAGE_SHIFT
;
1212 inode
->i_blocks
= 0;
1214 inode
->i_op
= &empty_dir_inode_operations
;
1215 inode
->i_opflags
&= ~IOP_XATTR
;
1216 inode
->i_fop
= &empty_dir_operations
;
1219 bool is_empty_dir_inode(struct inode
*inode
)
1221 return (inode
->i_fop
== &empty_dir_operations
) &&
1222 (inode
->i_op
== &empty_dir_inode_operations
);