3 * Library for filesystems writers.
6 #include <linux/module.h>
7 #include <linux/pagemap.h>
8 #include <linux/mount.h>
10 #include <linux/mutex.h>
11 #include <linux/exportfs.h>
12 #include <linux/writeback.h>
13 #include <linux/buffer_head.h>
15 #include <asm/uaccess.h>
17 int simple_getattr(struct vfsmount
*mnt
, struct dentry
*dentry
,
20 struct inode
*inode
= dentry
->d_inode
;
21 generic_fillattr(inode
, stat
);
22 stat
->blocks
= inode
->i_mapping
->nrpages
<< (PAGE_CACHE_SHIFT
- 9);
26 int simple_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
28 buf
->f_type
= dentry
->d_sb
->s_magic
;
29 buf
->f_bsize
= PAGE_CACHE_SIZE
;
30 buf
->f_namelen
= NAME_MAX
;
35 * Retaining negative dentries for an in-memory filesystem just wastes
36 * memory and lookup time: arrange for them to be deleted immediately.
38 static int simple_delete_dentry(struct dentry
*dentry
)
44 * Lookup the data. This is trivial - if the dentry didn't already
45 * exist, we know it is negative. Set d_op to delete negative dentries.
47 struct dentry
*simple_lookup(struct inode
*dir
, struct dentry
*dentry
, struct nameidata
*nd
)
49 static const struct dentry_operations simple_dentry_operations
= {
50 .d_delete
= simple_delete_dentry
,
53 if (dentry
->d_name
.len
> NAME_MAX
)
54 return ERR_PTR(-ENAMETOOLONG
);
55 dentry
->d_op
= &simple_dentry_operations
;
60 int simple_sync_file(struct file
* file
, struct dentry
*dentry
, int datasync
)
65 int dcache_dir_open(struct inode
*inode
, struct file
*file
)
67 static struct qstr cursor_name
= {.len
= 1, .name
= "."};
69 file
->private_data
= d_alloc(file
->f_path
.dentry
, &cursor_name
);
71 return file
->private_data
? 0 : -ENOMEM
;
74 int dcache_dir_close(struct inode
*inode
, struct file
*file
)
76 dput(file
->private_data
);
80 loff_t
dcache_dir_lseek(struct file
*file
, loff_t offset
, int origin
)
82 mutex_lock(&file
->f_path
.dentry
->d_inode
->i_mutex
);
85 offset
+= file
->f_pos
;
90 mutex_unlock(&file
->f_path
.dentry
->d_inode
->i_mutex
);
93 if (offset
!= file
->f_pos
) {
95 if (file
->f_pos
>= 2) {
97 struct dentry
*cursor
= file
->private_data
;
98 loff_t n
= file
->f_pos
- 2;
100 spin_lock(&dcache_lock
);
101 list_del(&cursor
->d_u
.d_child
);
102 p
= file
->f_path
.dentry
->d_subdirs
.next
;
103 while (n
&& p
!= &file
->f_path
.dentry
->d_subdirs
) {
105 next
= list_entry(p
, struct dentry
, d_u
.d_child
);
106 if (!d_unhashed(next
) && next
->d_inode
)
110 list_add_tail(&cursor
->d_u
.d_child
, p
);
111 spin_unlock(&dcache_lock
);
114 mutex_unlock(&file
->f_path
.dentry
->d_inode
->i_mutex
);
118 /* Relationship between i_mode and the DT_xxx types */
119 static inline unsigned char dt_type(struct inode
*inode
)
121 return (inode
->i_mode
>> 12) & 15;
125 * Directory is locked and all positive dentries in it are safe, since
126 * for ramfs-type trees they can't go away without unlink() or rmdir(),
127 * both impossible due to the lock on directory.
130 int dcache_readdir(struct file
* filp
, void * dirent
, filldir_t filldir
)
132 struct dentry
*dentry
= filp
->f_path
.dentry
;
133 struct dentry
*cursor
= filp
->private_data
;
134 struct list_head
*p
, *q
= &cursor
->d_u
.d_child
;
140 ino
= dentry
->d_inode
->i_ino
;
141 if (filldir(dirent
, ".", 1, i
, ino
, DT_DIR
) < 0)
147 ino
= parent_ino(dentry
);
148 if (filldir(dirent
, "..", 2, i
, ino
, DT_DIR
) < 0)
154 spin_lock(&dcache_lock
);
155 if (filp
->f_pos
== 2)
156 list_move(q
, &dentry
->d_subdirs
);
158 for (p
=q
->next
; p
!= &dentry
->d_subdirs
; p
=p
->next
) {
160 next
= list_entry(p
, struct dentry
, d_u
.d_child
);
161 if (d_unhashed(next
) || !next
->d_inode
)
164 spin_unlock(&dcache_lock
);
165 if (filldir(dirent
, next
->d_name
.name
,
166 next
->d_name
.len
, filp
->f_pos
,
167 next
->d_inode
->i_ino
,
168 dt_type(next
->d_inode
)) < 0)
170 spin_lock(&dcache_lock
);
171 /* next is still alive */
176 spin_unlock(&dcache_lock
);
181 ssize_t
generic_read_dir(struct file
*filp
, char __user
*buf
, size_t siz
, loff_t
*ppos
)
186 const struct file_operations simple_dir_operations
= {
187 .open
= dcache_dir_open
,
188 .release
= dcache_dir_close
,
189 .llseek
= dcache_dir_lseek
,
190 .read
= generic_read_dir
,
191 .readdir
= dcache_readdir
,
192 .fsync
= simple_sync_file
,
195 const struct inode_operations simple_dir_inode_operations
= {
196 .lookup
= simple_lookup
,
199 static const struct super_operations simple_super_operations
= {
200 .statfs
= simple_statfs
,
204 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
205 * will never be mountable)
207 int get_sb_pseudo(struct file_system_type
*fs_type
, char *name
,
208 const struct super_operations
*ops
, unsigned long magic
,
209 struct vfsmount
*mnt
)
211 struct super_block
*s
= sget(fs_type
, NULL
, set_anon_super
, NULL
);
212 struct dentry
*dentry
;
214 struct qstr d_name
= {.name
= name
, .len
= strlen(name
)};
219 s
->s_flags
= MS_NOUSER
;
220 s
->s_maxbytes
= MAX_LFS_FILESIZE
;
221 s
->s_blocksize
= PAGE_SIZE
;
222 s
->s_blocksize_bits
= PAGE_SHIFT
;
224 s
->s_op
= ops
? ops
: &simple_super_operations
;
230 * since this is the first inode, make it number 1. New inodes created
231 * after this must take care not to collide with it (by passing
232 * max_reserved of 1 to iunique).
235 root
->i_mode
= S_IFDIR
| S_IRUSR
| S_IWUSR
;
236 root
->i_atime
= root
->i_mtime
= root
->i_ctime
= CURRENT_TIME
;
237 dentry
= d_alloc(NULL
, &d_name
);
243 dentry
->d_parent
= dentry
;
244 d_instantiate(dentry
, root
);
246 s
->s_flags
|= MS_ACTIVE
;
247 simple_set_mnt(mnt
, s
);
251 deactivate_locked_super(s
);
255 int simple_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*dentry
)
257 struct inode
*inode
= old_dentry
->d_inode
;
259 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
261 atomic_inc(&inode
->i_count
);
263 d_instantiate(dentry
, inode
);
267 static inline int simple_positive(struct dentry
*dentry
)
269 return dentry
->d_inode
&& !d_unhashed(dentry
);
272 int simple_empty(struct dentry
*dentry
)
274 struct dentry
*child
;
277 spin_lock(&dcache_lock
);
278 list_for_each_entry(child
, &dentry
->d_subdirs
, d_u
.d_child
)
279 if (simple_positive(child
))
283 spin_unlock(&dcache_lock
);
287 int simple_unlink(struct inode
*dir
, struct dentry
*dentry
)
289 struct inode
*inode
= dentry
->d_inode
;
291 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
297 int simple_rmdir(struct inode
*dir
, struct dentry
*dentry
)
299 if (!simple_empty(dentry
))
302 drop_nlink(dentry
->d_inode
);
303 simple_unlink(dir
, dentry
);
308 int simple_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
309 struct inode
*new_dir
, struct dentry
*new_dentry
)
311 struct inode
*inode
= old_dentry
->d_inode
;
312 int they_are_dirs
= S_ISDIR(old_dentry
->d_inode
->i_mode
);
314 if (!simple_empty(new_dentry
))
317 if (new_dentry
->d_inode
) {
318 simple_unlink(new_dir
, new_dentry
);
321 } else if (they_are_dirs
) {
326 old_dir
->i_ctime
= old_dir
->i_mtime
= new_dir
->i_ctime
=
327 new_dir
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
332 int simple_readpage(struct file
*file
, struct page
*page
)
334 clear_highpage(page
);
335 flush_dcache_page(page
);
336 SetPageUptodate(page
);
341 int simple_prepare_write(struct file
*file
, struct page
*page
,
342 unsigned from
, unsigned to
)
344 if (!PageUptodate(page
)) {
345 if (to
- from
!= PAGE_CACHE_SIZE
)
346 zero_user_segments(page
,
348 to
, PAGE_CACHE_SIZE
);
353 int simple_write_begin(struct file
*file
, struct address_space
*mapping
,
354 loff_t pos
, unsigned len
, unsigned flags
,
355 struct page
**pagep
, void **fsdata
)
361 index
= pos
>> PAGE_CACHE_SHIFT
;
362 from
= pos
& (PAGE_CACHE_SIZE
- 1);
364 page
= grab_cache_page_write_begin(mapping
, index
, flags
);
370 return simple_prepare_write(file
, page
, from
, from
+len
);
373 static int simple_commit_write(struct file
*file
, struct page
*page
,
374 unsigned from
, unsigned to
)
376 struct inode
*inode
= page
->mapping
->host
;
377 loff_t pos
= ((loff_t
)page
->index
<< PAGE_CACHE_SHIFT
) + to
;
379 if (!PageUptodate(page
))
380 SetPageUptodate(page
);
382 * No need to use i_size_read() here, the i_size
383 * cannot change under us because we hold the i_mutex.
385 if (pos
> inode
->i_size
)
386 i_size_write(inode
, pos
);
387 set_page_dirty(page
);
391 int simple_write_end(struct file
*file
, struct address_space
*mapping
,
392 loff_t pos
, unsigned len
, unsigned copied
,
393 struct page
*page
, void *fsdata
)
395 unsigned from
= pos
& (PAGE_CACHE_SIZE
- 1);
397 /* zero the stale part of the page if we did a short copy */
399 void *kaddr
= kmap_atomic(page
, KM_USER0
);
400 memset(kaddr
+ from
+ copied
, 0, len
- copied
);
401 flush_dcache_page(page
);
402 kunmap_atomic(kaddr
, KM_USER0
);
405 simple_commit_write(file
, page
, from
, from
+copied
);
408 page_cache_release(page
);
414 * the inodes created here are not hashed. If you use iunique to generate
415 * unique inode values later for this filesystem, then you must take care
416 * to pass it an appropriate max_reserved value to avoid collisions.
418 int simple_fill_super(struct super_block
*s
, int magic
, struct tree_descr
*files
)
422 struct dentry
*dentry
;
425 s
->s_blocksize
= PAGE_CACHE_SIZE
;
426 s
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
428 s
->s_op
= &simple_super_operations
;
431 inode
= new_inode(s
);
435 * because the root inode is 1, the files array must not contain an
439 inode
->i_mode
= S_IFDIR
| 0755;
440 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
441 inode
->i_op
= &simple_dir_inode_operations
;
442 inode
->i_fop
= &simple_dir_operations
;
444 root
= d_alloc_root(inode
);
449 for (i
= 0; !files
->name
|| files
->name
[0]; i
++, files
++) {
453 /* warn if it tries to conflict with the root inode */
454 if (unlikely(i
== 1))
455 printk(KERN_WARNING
"%s: %s passed in a files array"
456 "with an index of 1!\n", __func__
,
459 dentry
= d_alloc_name(root
, files
->name
);
462 inode
= new_inode(s
);
465 inode
->i_mode
= S_IFREG
| files
->mode
;
466 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
467 inode
->i_fop
= files
->ops
;
469 d_add(dentry
, inode
);
479 static DEFINE_SPINLOCK(pin_fs_lock
);
481 int simple_pin_fs(struct file_system_type
*type
, struct vfsmount
**mount
, int *count
)
483 struct vfsmount
*mnt
= NULL
;
484 spin_lock(&pin_fs_lock
);
485 if (unlikely(!*mount
)) {
486 spin_unlock(&pin_fs_lock
);
487 mnt
= vfs_kern_mount(type
, 0, type
->name
, NULL
);
490 spin_lock(&pin_fs_lock
);
496 spin_unlock(&pin_fs_lock
);
501 void simple_release_fs(struct vfsmount
**mount
, int *count
)
503 struct vfsmount
*mnt
;
504 spin_lock(&pin_fs_lock
);
508 spin_unlock(&pin_fs_lock
);
513 * simple_read_from_buffer - copy data from the buffer to user space
514 * @to: the user space buffer to read to
515 * @count: the maximum number of bytes to read
516 * @ppos: the current position in the buffer
517 * @from: the buffer to read from
518 * @available: the size of the buffer
520 * The simple_read_from_buffer() function reads up to @count bytes from the
521 * buffer @from at offset @ppos into the user space address starting at @to.
523 * On success, the number of bytes read is returned and the offset @ppos is
524 * advanced by this number, or negative value is returned on error.
526 ssize_t
simple_read_from_buffer(void __user
*to
, size_t count
, loff_t
*ppos
,
527 const void *from
, size_t available
)
534 if (pos
>= available
|| !count
)
536 if (count
> available
- pos
)
537 count
= available
- pos
;
538 ret
= copy_to_user(to
, from
+ pos
, count
);
547 * memory_read_from_buffer - copy data from the buffer
548 * @to: the kernel space buffer to read to
549 * @count: the maximum number of bytes to read
550 * @ppos: the current position in the buffer
551 * @from: the buffer to read from
552 * @available: the size of the buffer
554 * The memory_read_from_buffer() function reads up to @count bytes from the
555 * buffer @from at offset @ppos into the kernel space address starting at @to.
557 * On success, the number of bytes read is returned and the offset @ppos is
558 * advanced by this number, or negative value is returned on error.
560 ssize_t
memory_read_from_buffer(void *to
, size_t count
, loff_t
*ppos
,
561 const void *from
, size_t available
)
567 if (pos
>= available
)
569 if (count
> available
- pos
)
570 count
= available
- pos
;
571 memcpy(to
, from
+ pos
, count
);
578 * Transaction based IO.
579 * The file expects a single write which triggers the transaction, and then
580 * possibly a read which collects the result - which is stored in a
584 void simple_transaction_set(struct file
*file
, size_t n
)
586 struct simple_transaction_argresp
*ar
= file
->private_data
;
588 BUG_ON(n
> SIMPLE_TRANSACTION_LIMIT
);
591 * The barrier ensures that ar->size will really remain zero until
592 * ar->data is ready for reading.
598 char *simple_transaction_get(struct file
*file
, const char __user
*buf
, size_t size
)
600 struct simple_transaction_argresp
*ar
;
601 static DEFINE_SPINLOCK(simple_transaction_lock
);
603 if (size
> SIMPLE_TRANSACTION_LIMIT
- 1)
604 return ERR_PTR(-EFBIG
);
606 ar
= (struct simple_transaction_argresp
*)get_zeroed_page(GFP_KERNEL
);
608 return ERR_PTR(-ENOMEM
);
610 spin_lock(&simple_transaction_lock
);
612 /* only one write allowed per open */
613 if (file
->private_data
) {
614 spin_unlock(&simple_transaction_lock
);
615 free_page((unsigned long)ar
);
616 return ERR_PTR(-EBUSY
);
619 file
->private_data
= ar
;
621 spin_unlock(&simple_transaction_lock
);
623 if (copy_from_user(ar
->data
, buf
, size
))
624 return ERR_PTR(-EFAULT
);
629 ssize_t
simple_transaction_read(struct file
*file
, char __user
*buf
, size_t size
, loff_t
*pos
)
631 struct simple_transaction_argresp
*ar
= file
->private_data
;
635 return simple_read_from_buffer(buf
, size
, pos
, ar
->data
, ar
->size
);
638 int simple_transaction_release(struct inode
*inode
, struct file
*file
)
640 free_page((unsigned long)file
->private_data
);
644 /* Simple attribute files */
647 int (*get
)(void *, u64
*);
648 int (*set
)(void *, u64
);
649 char get_buf
[24]; /* enough to store a u64 and "\n\0" */
652 const char *fmt
; /* format for read operation */
653 struct mutex mutex
; /* protects access to these buffers */
656 /* simple_attr_open is called by an actual attribute open file operation
657 * to set the attribute specific access operations. */
658 int simple_attr_open(struct inode
*inode
, struct file
*file
,
659 int (*get
)(void *, u64
*), int (*set
)(void *, u64
),
662 struct simple_attr
*attr
;
664 attr
= kmalloc(sizeof(*attr
), GFP_KERNEL
);
670 attr
->data
= inode
->i_private
;
672 mutex_init(&attr
->mutex
);
674 file
->private_data
= attr
;
676 return nonseekable_open(inode
, file
);
679 int simple_attr_release(struct inode
*inode
, struct file
*file
)
681 kfree(file
->private_data
);
685 /* read from the buffer that is filled with the get function */
686 ssize_t
simple_attr_read(struct file
*file
, char __user
*buf
,
687 size_t len
, loff_t
*ppos
)
689 struct simple_attr
*attr
;
693 attr
= file
->private_data
;
698 ret
= mutex_lock_interruptible(&attr
->mutex
);
702 if (*ppos
) { /* continued read */
703 size
= strlen(attr
->get_buf
);
704 } else { /* first read */
706 ret
= attr
->get(attr
->data
, &val
);
710 size
= scnprintf(attr
->get_buf
, sizeof(attr
->get_buf
),
711 attr
->fmt
, (unsigned long long)val
);
714 ret
= simple_read_from_buffer(buf
, len
, ppos
, attr
->get_buf
, size
);
716 mutex_unlock(&attr
->mutex
);
720 /* interpret the buffer as a number to call the set function with */
721 ssize_t
simple_attr_write(struct file
*file
, const char __user
*buf
,
722 size_t len
, loff_t
*ppos
)
724 struct simple_attr
*attr
;
729 attr
= file
->private_data
;
733 ret
= mutex_lock_interruptible(&attr
->mutex
);
738 size
= min(sizeof(attr
->set_buf
) - 1, len
);
739 if (copy_from_user(attr
->set_buf
, buf
, size
))
742 attr
->set_buf
[size
] = '\0';
743 val
= simple_strtol(attr
->set_buf
, NULL
, 0);
744 ret
= attr
->set(attr
->data
, val
);
746 ret
= len
; /* on success, claim we got the whole input */
748 mutex_unlock(&attr
->mutex
);
753 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
754 * @sb: filesystem to do the file handle conversion on
755 * @fid: file handle to convert
756 * @fh_len: length of the file handle in bytes
757 * @fh_type: type of file handle
758 * @get_inode: filesystem callback to retrieve inode
760 * This function decodes @fid as long as it has one of the well-known
761 * Linux filehandle types and calls @get_inode on it to retrieve the
762 * inode for the object specified in the file handle.
764 struct dentry
*generic_fh_to_dentry(struct super_block
*sb
, struct fid
*fid
,
765 int fh_len
, int fh_type
, struct inode
*(*get_inode
)
766 (struct super_block
*sb
, u64 ino
, u32 gen
))
768 struct inode
*inode
= NULL
;
774 case FILEID_INO32_GEN
:
775 case FILEID_INO32_GEN_PARENT
:
776 inode
= get_inode(sb
, fid
->i32
.ino
, fid
->i32
.gen
);
780 return d_obtain_alias(inode
);
782 EXPORT_SYMBOL_GPL(generic_fh_to_dentry
);
785 * generic_fh_to_dentry - generic helper for the fh_to_parent export operation
786 * @sb: filesystem to do the file handle conversion on
787 * @fid: file handle to convert
788 * @fh_len: length of the file handle in bytes
789 * @fh_type: type of file handle
790 * @get_inode: filesystem callback to retrieve inode
792 * This function decodes @fid as long as it has one of the well-known
793 * Linux filehandle types and calls @get_inode on it to retrieve the
794 * inode for the _parent_ object specified in the file handle if it
795 * is specified in the file handle, or NULL otherwise.
797 struct dentry
*generic_fh_to_parent(struct super_block
*sb
, struct fid
*fid
,
798 int fh_len
, int fh_type
, struct inode
*(*get_inode
)
799 (struct super_block
*sb
, u64 ino
, u32 gen
))
801 struct inode
*inode
= NULL
;
807 case FILEID_INO32_GEN_PARENT
:
808 inode
= get_inode(sb
, fid
->i32
.parent_ino
,
809 (fh_len
> 3 ? fid
->i32
.parent_gen
: 0));
813 return d_obtain_alias(inode
);
815 EXPORT_SYMBOL_GPL(generic_fh_to_parent
);
817 int simple_fsync(struct file
*file
, struct dentry
*dentry
, int datasync
)
819 struct writeback_control wbc
= {
820 .sync_mode
= WB_SYNC_ALL
,
821 .nr_to_write
= 0, /* metadata-only; caller takes care of data */
823 struct inode
*inode
= dentry
->d_inode
;
827 ret
= sync_mapping_buffers(inode
->i_mapping
);
828 if (!(inode
->i_state
& I_DIRTY
))
830 if (datasync
&& !(inode
->i_state
& I_DIRTY_DATASYNC
))
833 err
= sync_inode(inode
, &wbc
);
838 EXPORT_SYMBOL(simple_fsync
);
840 EXPORT_SYMBOL(dcache_dir_close
);
841 EXPORT_SYMBOL(dcache_dir_lseek
);
842 EXPORT_SYMBOL(dcache_dir_open
);
843 EXPORT_SYMBOL(dcache_readdir
);
844 EXPORT_SYMBOL(generic_read_dir
);
845 EXPORT_SYMBOL(get_sb_pseudo
);
846 EXPORT_SYMBOL(simple_write_begin
);
847 EXPORT_SYMBOL(simple_write_end
);
848 EXPORT_SYMBOL(simple_dir_inode_operations
);
849 EXPORT_SYMBOL(simple_dir_operations
);
850 EXPORT_SYMBOL(simple_empty
);
851 EXPORT_SYMBOL(d_alloc_name
);
852 EXPORT_SYMBOL(simple_fill_super
);
853 EXPORT_SYMBOL(simple_getattr
);
854 EXPORT_SYMBOL(simple_link
);
855 EXPORT_SYMBOL(simple_lookup
);
856 EXPORT_SYMBOL(simple_pin_fs
);
857 EXPORT_UNUSED_SYMBOL(simple_prepare_write
);
858 EXPORT_SYMBOL(simple_readpage
);
859 EXPORT_SYMBOL(simple_release_fs
);
860 EXPORT_SYMBOL(simple_rename
);
861 EXPORT_SYMBOL(simple_rmdir
);
862 EXPORT_SYMBOL(simple_statfs
);
863 EXPORT_SYMBOL(simple_sync_file
);
864 EXPORT_SYMBOL(simple_unlink
);
865 EXPORT_SYMBOL(simple_read_from_buffer
);
866 EXPORT_SYMBOL(memory_read_from_buffer
);
867 EXPORT_SYMBOL(simple_transaction_set
);
868 EXPORT_SYMBOL(simple_transaction_get
);
869 EXPORT_SYMBOL(simple_transaction_read
);
870 EXPORT_SYMBOL(simple_transaction_release
);
871 EXPORT_SYMBOL_GPL(simple_attr_open
);
872 EXPORT_SYMBOL_GPL(simple_attr_release
);
873 EXPORT_SYMBOL_GPL(simple_attr_read
);
874 EXPORT_SYMBOL_GPL(simple_attr_write
);