[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / libfs.c

/*
 *	fs/libfs.c
 *	Library for filesystems writers.
 */

#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/vfs.h>
#include <linux/mutex.h>

#include <asm/uaccess.h>

int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
		   struct kstat *stat)
{
	struct inode *inode = dentry->d_inode;
	generic_fillattr(inode, stat);
	stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
	return 0;
}

int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
{
	buf->f_type = dentry->d_sb->s_magic;
	buf->f_bsize = PAGE_CACHE_SIZE;
	buf->f_namelen = NAME_MAX;
	return 0;
}

/*
 * Retaining negative dentries for an in-memory filesystem just wastes
 * memory and lookup time: arrange for them to be deleted immediately.
 */
static int simple_delete_dentry(struct dentry *dentry)
{
	return 1;
}

/*
 * Lookup the data. This is trivial - if the dentry didn't already
 * exist, we know it is negative.  Set d_op to delete negative dentries.
 */
struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
	static struct dentry_operations simple_dentry_operations = {
		.d_delete = simple_delete_dentry,
	};

	if (dentry->d_name.len > NAME_MAX)
		return ERR_PTR(-ENAMETOOLONG);
	dentry->d_op = &simple_dentry_operations;
	d_add(dentry, NULL);
	return NULL;
}

int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
{
	return 0;
}
 
int dcache_dir_open(struct inode *inode, struct file *file)
{
	static struct qstr cursor_name = {.len = 1, .name = "."};

	file->private_data = d_alloc(file->f_path.dentry, &cursor_name);

	return file->private_data ? 0 : -ENOMEM;
}

int dcache_dir_close(struct inode *inode, struct file *file)
{
	dput(file->private_data);
	return 0;
}

loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
{
	mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
	switch (origin) {
		case 1:
			offset += file->f_pos;
		case 0:
			if (offset >= 0)
				break;
		default:
			mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
			return -EINVAL;
	}
	if (offset != file->f_pos) {
		file->f_pos = offset;
		if (file->f_pos >= 2) {
			struct list_head *p;
			struct dentry *cursor = file->private_data;
			loff_t n = file->f_pos - 2;

			spin_lock(&dcache_lock);
			list_del(&cursor->d_u.d_child);
			p = file->f_path.dentry->d_subdirs.next;
			while (n && p != &file->f_path.dentry->d_subdirs) {
				struct dentry *next;
				next = list_entry(p, struct dentry, d_u.d_child);
				if (!d_unhashed(next) && next->d_inode)
					n--;
				p = p->next;
			}
			list_add_tail(&cursor->d_u.d_child, p);
			spin_unlock(&dcache_lock);
		}
	}
	mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
	return offset;
}

/* Relationship between i_mode and the DT_xxx types */
static inline unsigned char dt_type(struct inode *inode)
{
	return (inode->i_mode >> 12) & 15;
}

/*
 * Directory is locked and all positive dentries in it are safe, since
 * for ramfs-type trees they can't go away without unlink() or rmdir(),
 * both impossible due to the lock on directory.
 */

int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
	struct dentry *dentry = filp->f_path.dentry;
	struct dentry *cursor = filp->private_data;
	struct list_head *p, *q = &cursor->d_u.d_child;
	ino_t ino;
	int i = filp->f_pos;

	switch (i) {
		case 0:
			ino = dentry->d_inode->i_ino;
			if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
				break;
			filp->f_pos++;
			i++;
			/* fallthrough */
		case 1:
			ino = parent_ino(dentry);
			if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
				break;
			filp->f_pos++;
			i++;
			/* fallthrough */
		default:
			spin_lock(&dcache_lock);
			if (filp->f_pos == 2)
				list_move(q, &dentry->d_subdirs);

			for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
				struct dentry *next;
				next = list_entry(p, struct dentry, d_u.d_child);
				if (d_unhashed(next) || !next->d_inode)
					continue;

				spin_unlock(&dcache_lock);
				if (filldir(dirent, next->d_name.name, 
					    next->d_name.len, filp->f_pos, 
					    next->d_inode->i_ino, 
					    dt_type(next->d_inode)) < 0)
					return 0;
				spin_lock(&dcache_lock);
				/* next is still alive */
				list_move(q, p);
				p = q;
				filp->f_pos++;
			}
			spin_unlock(&dcache_lock);
	}
	return 0;
}

ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
{
	return -EISDIR;
}

const struct file_operations simple_dir_operations = {
	.open		= dcache_dir_open,
	.release	= dcache_dir_close,
	.llseek		= dcache_dir_lseek,
	.read		= generic_read_dir,
	.readdir	= dcache_readdir,
	.fsync		= simple_sync_file,
};

const struct inode_operations simple_dir_inode_operations = {
	.lookup		= simple_lookup,
};

static const struct super_operations simple_super_operations = {
	.statfs		= simple_statfs,
};

/*
 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
 * will never be mountable)
 */
int get_sb_pseudo(struct file_system_type *fs_type, char *name,
	const struct super_operations *ops, unsigned long magic,
	struct vfsmount *mnt)
{
	struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
	struct dentry *dentry;
	struct inode *root;
	struct qstr d_name = {.name = name, .len = strlen(name)};

	if (IS_ERR(s))
		return PTR_ERR(s);

	s->s_flags = MS_NOUSER;
	s->s_maxbytes = ~0ULL;
	s->s_blocksize = 1024;
	s->s_blocksize_bits = 10;
	s->s_magic = magic;
	s->s_op = ops ? ops : &simple_super_operations;
	s->s_time_gran = 1;
	root = new_inode(s);
	if (!root)
		goto Enomem;
	/*
	 * since this is the first inode, make it number 1. New inodes created
	 * after this must take care not to collide with it (by passing
	 * max_reserved of 1 to iunique).
	 */
	root->i_ino = 1;
	root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
	root->i_uid = root->i_gid = 0;
	root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
	dentry = d_alloc(NULL, &d_name);
	if (!dentry) {
		iput(root);
		goto Enomem;
	}
	dentry->d_sb = s;
	dentry->d_parent = dentry;
	d_instantiate(dentry, root);
	s->s_root = dentry;
	s->s_flags |= MS_ACTIVE;
	return simple_set_mnt(mnt, s);

Enomem:
	up_write(&s->s_umount);
	deactivate_super(s);
	return -ENOMEM;
}

int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = old_dentry->d_inode;

	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	inc_nlink(inode);
	atomic_inc(&inode->i_count);
	dget(dentry);
	d_instantiate(dentry, inode);
	return 0;
}

static inline int simple_positive(struct dentry *dentry)
{
	return dentry->d_inode && !d_unhashed(dentry);
}

int simple_empty(struct dentry *dentry)
{
	struct dentry *child;
	int ret = 0;

	spin_lock(&dcache_lock);
	list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
		if (simple_positive(child))
			goto out;
	ret = 1;
out:
	spin_unlock(&dcache_lock);
	return ret;
}

int simple_unlink(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = dentry->d_inode;

	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	drop_nlink(inode);
	dput(dentry);
	return 0;
}

int simple_rmdir(struct inode *dir, struct dentry *dentry)
{
	if (!simple_empty(dentry))
		return -ENOTEMPTY;

	drop_nlink(dentry->d_inode);
	simple_unlink(dir, dentry);
	drop_nlink(dir);
	return 0;
}

int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
		struct inode *new_dir, struct dentry *new_dentry)
{
	struct inode *inode = old_dentry->d_inode;
	int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);

	if (!simple_empty(new_dentry))
		return -ENOTEMPTY;

	if (new_dentry->d_inode) {
		simple_unlink(new_dir, new_dentry);
		if (they_are_dirs)
			drop_nlink(old_dir);
	} else if (they_are_dirs) {
		drop_nlink(old_dir);
		inc_nlink(new_dir);
	}

	old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
		new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;

	return 0;
}

int simple_readpage(struct file *file, struct page *page)
{
	clear_highpage(page);
	flush_dcache_page(page);
	SetPageUptodate(page);
	unlock_page(page);
	return 0;
}

int simple_prepare_write(struct file *file, struct page *page,
			unsigned from, unsigned to)
{
	if (!PageUptodate(page)) {
		if (to - from != PAGE_CACHE_SIZE) {
			void *kaddr = kmap_atomic(page, KM_USER0);
			memset(kaddr, 0, from);
			memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
			flush_dcache_page(page);
			kunmap_atomic(kaddr, KM_USER0);
		}
	}
	return 0;
}

int simple_write_begin(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned flags,
			struct page **pagep, void **fsdata)
{
	struct page *page;
	pgoff_t index;
	unsigned from;

	index = pos >> PAGE_CACHE_SHIFT;
	from = pos & (PAGE_CACHE_SIZE - 1);

	page = __grab_cache_page(mapping, index);
	if (!page)
		return -ENOMEM;

	*pagep = page;

	return simple_prepare_write(file, page, from, from+len);
}

static int simple_commit_write(struct file *file, struct page *page,
			       unsigned from, unsigned to)
{
	struct inode *inode = page->mapping->host;
	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;

	if (!PageUptodate(page))
		SetPageUptodate(page);
	/*
	 * No need to use i_size_read() here, the i_size
	 * cannot change under us because we hold the i_mutex.
	 */
	if (pos > inode->i_size)
		i_size_write(inode, pos);
	set_page_dirty(page);
	return 0;
}

int simple_write_end(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned copied,
			struct page *page, void *fsdata)
{
	unsigned from = pos & (PAGE_CACHE_SIZE - 1);

	/* zero the stale part of the page if we did a short copy */
	if (copied < len) {
		void *kaddr = kmap_atomic(page, KM_USER0);
		memset(kaddr + from + copied, 0, len - copied);
		flush_dcache_page(page);
		kunmap_atomic(kaddr, KM_USER0);
	}

	simple_commit_write(file, page, from, from+copied);

	unlock_page(page);
	page_cache_release(page);

	return copied;
}

/*
 * the inodes created here are not hashed. If you use iunique to generate
 * unique inode values later for this filesystem, then you must take care
 * to pass it an appropriate max_reserved value to avoid collisions.
 */
int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
{
	struct inode *inode;
	struct dentry *root;
	struct dentry *dentry;
	int i;

	s->s_blocksize = PAGE_CACHE_SIZE;
	s->s_blocksize_bits = PAGE_CACHE_SHIFT;
	s->s_magic = magic;
	s->s_op = &simple_super_operations;
	s->s_time_gran = 1;

	inode = new_inode(s);
	if (!inode)
		return -ENOMEM;
	/*
	 * because the root inode is 1, the files array must not contain an
	 * entry at index 1
	 */
	inode->i_ino = 1;
	inode->i_mode = S_IFDIR | 0755;
	inode->i_uid = inode->i_gid = 0;
	inode->i_blocks = 0;
	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	inode->i_op = &simple_dir_inode_operations;
	inode->i_fop = &simple_dir_operations;
	inode->i_nlink = 2;
	root = d_alloc_root(inode);
	if (!root) {
		iput(inode);
		return -ENOMEM;
	}
	for (i = 0; !files->name || files->name[0]; i++, files++) {
		if (!files->name)
			continue;

		/* warn if it tries to conflict with the root inode */
		if (unlikely(i == 1))
			printk(KERN_WARNING "%s: %s passed in a files array"
				"with an index of 1!\n", __func__,
				s->s_type->name);

		dentry = d_alloc_name(root, files->name);
		if (!dentry)
			goto out;
		inode = new_inode(s);
		if (!inode)
			goto out;
		inode->i_mode = S_IFREG | files->mode;
		inode->i_uid = inode->i_gid = 0;
		inode->i_blocks = 0;
		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
		inode->i_fop = files->ops;
		inode->i_ino = i;
		d_add(dentry, inode);
	}
	s->s_root = root;
	return 0;
out:
	d_genocide(root);
	dput(root);
	return -ENOMEM;
}

static DEFINE_SPINLOCK(pin_fs_lock);

int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
{
	struct vfsmount *mnt = NULL;
	spin_lock(&pin_fs_lock);
	if (unlikely(!*mount)) {
		spin_unlock(&pin_fs_lock);
		mnt = vfs_kern_mount(type, 0, type->name, NULL);
		if (IS_ERR(mnt))
			return PTR_ERR(mnt);
		spin_lock(&pin_fs_lock);
		if (!*mount)
			*mount = mnt;
	}
	mntget(*mount);
	++*count;
	spin_unlock(&pin_fs_lock);
	mntput(mnt);
	return 0;
}

void simple_release_fs(struct vfsmount **mount, int *count)
{
	struct vfsmount *mnt;
	spin_lock(&pin_fs_lock);
	mnt = *mount;
	if (!--*count)
		*mount = NULL;
	spin_unlock(&pin_fs_lock);
	mntput(mnt);
}

ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
				const void *from, size_t available)
{
	loff_t pos = *ppos;
	if (pos < 0)
		return -EINVAL;
	if (pos >= available)
		return 0;
	if (count > available - pos)
		count = available - pos;
	if (copy_to_user(to, from + pos, count))
		return -EFAULT;
	*ppos = pos + count;
	return count;
}

/*
 * Transaction based IO.
 * The file expects a single write which triggers the transaction, and then
 * possibly a read which collects the result - which is stored in a
 * file-local buffer.
 */
char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
{
	struct simple_transaction_argresp *ar;
	static DEFINE_SPINLOCK(simple_transaction_lock);

	if (size > SIMPLE_TRANSACTION_LIMIT - 1)
		return ERR_PTR(-EFBIG);

	ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
	if (!ar)
		return ERR_PTR(-ENOMEM);

	spin_lock(&simple_transaction_lock);

	/* only one write allowed per open */
	if (file->private_data) {
		spin_unlock(&simple_transaction_lock);
		free_page((unsigned long)ar);
		return ERR_PTR(-EBUSY);
	}

	file->private_data = ar;

	spin_unlock(&simple_transaction_lock);

	if (copy_from_user(ar->data, buf, size))
		return ERR_PTR(-EFAULT);

	return ar->data;
}

ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
{
	struct simple_transaction_argresp *ar = file->private_data;

	if (!ar)
		return 0;
	return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
}

int simple_transaction_release(struct inode *inode, struct file *file)
{
	free_page((unsigned long)file->private_data);
	return 0;
}

/* Simple attribute files */

struct simple_attr {
	u64 (*get)(void *);
	void (*set)(void *, u64);
	char get_buf[24];	/* enough to store a u64 and "\n\0" */
	char set_buf[24];
	void *data;
	const char *fmt;	/* format for read operation */
	struct mutex mutex;	/* protects access to these buffers */
};

/* simple_attr_open is called by an actual attribute open file operation
 * to set the attribute specific access operations. */
int simple_attr_open(struct inode *inode, struct file *file,
		     u64 (*get)(void *), void (*set)(void *, u64),
		     const char *fmt)
{
	struct simple_attr *attr;

	attr = kmalloc(sizeof(*attr), GFP_KERNEL);
	if (!attr)
		return -ENOMEM;

	attr->get = get;
	attr->set = set;
	attr->data = inode->i_private;
	attr->fmt = fmt;
	mutex_init(&attr->mutex);

	file->private_data = attr;

	return nonseekable_open(inode, file);
}

int simple_attr_close(struct inode *inode, struct file *file)
{
	kfree(file->private_data);
	return 0;
}

/* read from the buffer that is filled with the get function */
ssize_t simple_attr_read(struct file *file, char __user *buf,
			 size_t len, loff_t *ppos)
{
	struct simple_attr *attr;
	size_t size;
	ssize_t ret;

	attr = file->private_data;

	if (!attr->get)
		return -EACCES;

	mutex_lock(&attr->mutex);
	if (*ppos) /* continued read */
		size = strlen(attr->get_buf);
	else	  /* first read */
		size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
				 attr->fmt,
				 (unsigned long long)attr->get(attr->data));

	ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
	mutex_unlock(&attr->mutex);
	return ret;
}

/* interpret the buffer as a number to call the set function with */
ssize_t simple_attr_write(struct file *file, const char __user *buf,
			  size_t len, loff_t *ppos)
{
	struct simple_attr *attr;
	u64 val;
	size_t size;
	ssize_t ret;

	attr = file->private_data;

	if (!attr->set)
		return -EACCES;

	mutex_lock(&attr->mutex);
	ret = -EFAULT;
	size = min(sizeof(attr->set_buf) - 1, len);
	if (copy_from_user(attr->set_buf, buf, size))
		goto out;

	ret = len; /* claim we got the whole input */
	attr->set_buf[size] = '\0';
	val = simple_strtol(attr->set_buf, NULL, 0);
	attr->set(attr->data, val);
out:
	mutex_unlock(&attr->mutex);
	return ret;
}

EXPORT_SYMBOL(dcache_dir_close);
EXPORT_SYMBOL(dcache_dir_lseek);
EXPORT_SYMBOL(dcache_dir_open);
EXPORT_SYMBOL(dcache_readdir);
EXPORT_SYMBOL(generic_read_dir);
EXPORT_SYMBOL(get_sb_pseudo);
EXPORT_SYMBOL(simple_write_begin);
EXPORT_SYMBOL(simple_write_end);
EXPORT_SYMBOL(simple_dir_inode_operations);
EXPORT_SYMBOL(simple_dir_operations);
EXPORT_SYMBOL(simple_empty);
EXPORT_SYMBOL(d_alloc_name);
EXPORT_SYMBOL(simple_fill_super);
EXPORT_SYMBOL(simple_getattr);
EXPORT_SYMBOL(simple_link);
EXPORT_SYMBOL(simple_lookup);
EXPORT_SYMBOL(simple_pin_fs);
EXPORT_SYMBOL(simple_prepare_write);
EXPORT_SYMBOL(simple_readpage);
EXPORT_SYMBOL(simple_release_fs);
EXPORT_SYMBOL(simple_rename);
EXPORT_SYMBOL(simple_rmdir);
EXPORT_SYMBOL(simple_statfs);
EXPORT_SYMBOL(simple_sync_file);
EXPORT_SYMBOL(simple_unlink);
EXPORT_SYMBOL(simple_read_from_buffer);
EXPORT_SYMBOL(simple_transaction_get);
EXPORT_SYMBOL(simple_transaction_read);
EXPORT_SYMBOL(simple_transaction_release);
EXPORT_SYMBOL_GPL(simple_attr_open);
EXPORT_SYMBOL_GPL(simple_attr_close);
EXPORT_SYMBOL_GPL(simple_attr_read);
EXPORT_SYMBOL_GPL(simple_attr_write);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* fs/libfs.c
	3	* Library for filesystems writers.
	4	*/
	5
	6	#include <linux/module.h>
	7	#include <linux/pagemap.h>
	8	#include <linux/mount.h>
	9	#include <linux/vfs.h>
7cf34c76 IM	10	#include <linux/mutex.h>
7cf34c76 IM	11
1da177e4 LT	12	#include <asm/uaccess.h>
	13
	14	int simple_getattr(struct vfsmount mnt, struct dentry dentry,
	15	struct kstat *stat)
	16	{
	17	struct inode *inode = dentry->d_inode;
	18	generic_fillattr(inode, stat);
	19	stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
	20	return 0;
	21	}
	22
726c3342	23	int simple_statfs(struct dentry dentry, struct kstatfs buf)
1da177e4	24	{
726c3342	25	buf->f_type = dentry->d_sb->s_magic;
1da177e4 LT	26	buf->f_bsize = PAGE_CACHE_SIZE;
	27	buf->f_namelen = NAME_MAX;
	28	return 0;
	29	}
	30
	31	/*
	32	* Retaining negative dentries for an in-memory filesystem just wastes
	33	* memory and lookup time: arrange for them to be deleted immediately.
	34	*/
	35	static int simple_delete_dentry(struct dentry *dentry)
	36	{
	37	return 1;
	38	}
	39
	40	/*
	41	* Lookup the data. This is trivial - if the dentry didn't already
	42	* exist, we know it is negative. Set d_op to delete negative dentries.
	43	*/
	44	struct dentry simple_lookup(struct inode dir, struct dentry dentry, struct nameidata nd)
	45	{
	46	static struct dentry_operations simple_dentry_operations = {
	47	.d_delete = simple_delete_dentry,
	48	};
	49
	50	if (dentry->d_name.len > NAME_MAX)
	51	return ERR_PTR(-ENAMETOOLONG);
	52	dentry->d_op = &simple_dentry_operations;
	53	d_add(dentry, NULL);
	54	return NULL;
	55	}
	56
	57	int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
	58	{
	59	return 0;
	60	}
	61
	62	int dcache_dir_open(struct inode inode, struct file file)
	63	{
	64	static struct qstr cursor_name = {.len = 1, .name = "."};
	65
0f7fc9e4	66	file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
1da177e4 LT	67
	68	return file->private_data ? 0 : -ENOMEM;
	69	}
	70
	71	int dcache_dir_close(struct inode inode, struct file file)
	72	{
	73	dput(file->private_data);
	74	return 0;
	75	}
	76
	77	loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
	78	{
0f7fc9e4	79	mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
1da177e4 LT	80	switch (origin) {
	81	case 1:
	82	offset += file->f_pos;
	83	case 0:
	84	if (offset >= 0)
	85	break;
	86	default:
0f7fc9e4	87	mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
1da177e4 LT	88	return -EINVAL;
	89	}
	90	if (offset != file->f_pos) {
	91	file->f_pos = offset;
	92	if (file->f_pos >= 2) {
	93	struct list_head *p;
	94	struct dentry *cursor = file->private_data;
	95	loff_t n = file->f_pos - 2;
	96
	97	spin_lock(&dcache_lock);
5160ee6f	98	list_del(&cursor->d_u.d_child);
0f7fc9e4 JJS	99	p = file->f_path.dentry->d_subdirs.next;
0f7fc9e4 JJS	100	while (n && p != &file->f_path.dentry->d_subdirs) {
1da177e4	101	struct dentry *next;
5160ee6f	102	next = list_entry(p, struct dentry, d_u.d_child);
1da177e4 LT	103	if (!d_unhashed(next) && next->d_inode)
	104	n--;
	105	p = p->next;
	106	}
5160ee6f	107	list_add_tail(&cursor->d_u.d_child, p);
1da177e4 LT	108	spin_unlock(&dcache_lock);
	109	}
	110	}
0f7fc9e4	111	mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
1da177e4 LT	112	return offset;
	113	}
	114
	115	/* Relationship between i_mode and the DT_xxx types */
	116	static inline unsigned char dt_type(struct inode *inode)
	117	{
	118	return (inode->i_mode >> 12) & 15;
	119	}
	120
	121	/*
	122	* Directory is locked and all positive dentries in it are safe, since
	123	* for ramfs-type trees they can't go away without unlink() or rmdir(),
	124	* both impossible due to the lock on directory.
	125	*/
	126
	127	int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
	128	{
0f7fc9e4	129	struct dentry *dentry = filp->f_path.dentry;
1da177e4	130	struct dentry *cursor = filp->private_data;
5160ee6f	131	struct list_head p, q = &cursor->d_u.d_child;
1da177e4 LT	132	ino_t ino;
	133	int i = filp->f_pos;
	134
	135	switch (i) {
	136	case 0:
	137	ino = dentry->d_inode->i_ino;
	138	if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
	139	break;
	140	filp->f_pos++;
	141	i++;
	142	/* fallthrough */
	143	case 1:
	144	ino = parent_ino(dentry);
	145	if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
	146	break;
	147	filp->f_pos++;
	148	i++;
	149	/* fallthrough */
	150	default:
	151	spin_lock(&dcache_lock);
1bfba4e8 AM	152	if (filp->f_pos == 2)
	153	list_move(q, &dentry->d_subdirs);
	154
1da177e4 LT	155	for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
1da177e4 LT	156	struct dentry *next;
5160ee6f	157	next = list_entry(p, struct dentry, d_u.d_child);
1da177e4 LT	158	if (d_unhashed(next) \|\| !next->d_inode)
	159	continue;
	160
	161	spin_unlock(&dcache_lock);
0f8952c2 RN	162	if (filldir(dirent, next->d_name.name,
	163	next->d_name.len, filp->f_pos,
	164	next->d_inode->i_ino,
	165	dt_type(next->d_inode)) < 0)
1da177e4 LT	166	return 0;
	167	spin_lock(&dcache_lock);
	168	/* next is still alive */
1bfba4e8	169	list_move(q, p);
1da177e4 LT	170	p = q;
	171	filp->f_pos++;
	172	}
	173	spin_unlock(&dcache_lock);
	174	}
	175	return 0;
	176	}
	177
	178	ssize_t generic_read_dir(struct file filp, char __user buf, size_t siz, loff_t *ppos)
	179	{
	180	return -EISDIR;
	181	}
	182
4b6f5d20	183	const struct file_operations simple_dir_operations = {
1da177e4 LT	184	.open = dcache_dir_open,
	185	.release = dcache_dir_close,
	186	.llseek = dcache_dir_lseek,
	187	.read = generic_read_dir,
	188	.readdir = dcache_readdir,
8ae0b778	189	.fsync = simple_sync_file,
1da177e4 LT	190	};
1da177e4 LT	191
92e1d5be	192	const struct inode_operations simple_dir_inode_operations = {
1da177e4 LT	193	.lookup = simple_lookup,
	194	};
	195
759b9775 HD	196	static const struct super_operations simple_super_operations = {
	197	.statfs = simple_statfs,
	198	};
	199
1da177e4 LT	200	/*
	201	* Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
	202	* will never be mountable)
	203	*/
454e2398	204	int get_sb_pseudo(struct file_system_type fs_type, char name,
ee9b6d61	205	const struct super_operations *ops, unsigned long magic,
454e2398	206	struct vfsmount *mnt)
1da177e4 LT	207	{
1da177e4 LT	208	struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
1da177e4 LT	209	struct dentry *dentry;
	210	struct inode *root;
	211	struct qstr d_name = {.name = name, .len = strlen(name)};
	212
	213	if (IS_ERR(s))
454e2398	214	return PTR_ERR(s);
1da177e4 LT	215
	216	s->s_flags = MS_NOUSER;
	217	s->s_maxbytes = ~0ULL;
	218	s->s_blocksize = 1024;
	219	s->s_blocksize_bits = 10;
	220	s->s_magic = magic;
759b9775	221	s->s_op = ops ? ops : &simple_super_operations;
1da177e4 LT	222	s->s_time_gran = 1;
	223	root = new_inode(s);
	224	if (!root)
	225	goto Enomem;
1a1c9bb4 JL	226	/*
	227	* since this is the first inode, make it number 1. New inodes created
	228	* after this must take care not to collide with it (by passing
	229	* max_reserved of 1 to iunique).
	230	*/
	231	root->i_ino = 1;
1da177e4 LT	232	root->i_mode = S_IFDIR \| S_IRUSR \| S_IWUSR;
	233	root->i_uid = root->i_gid = 0;
	234	root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
	235	dentry = d_alloc(NULL, &d_name);
	236	if (!dentry) {
	237	iput(root);
	238	goto Enomem;
	239	}
	240	dentry->d_sb = s;
	241	dentry->d_parent = dentry;
	242	d_instantiate(dentry, root);
	243	s->s_root = dentry;
	244	s->s_flags \|= MS_ACTIVE;
454e2398	245	return simple_set_mnt(mnt, s);
1da177e4 LT	246
	247	Enomem:
	248	up_write(&s->s_umount);
	249	deactivate_super(s);
454e2398	250	return -ENOMEM;
1da177e4 LT	251	}
	252
	253	int simple_link(struct dentry old_dentry, struct inode dir, struct dentry *dentry)
	254	{
	255	struct inode *inode = old_dentry->d_inode;
	256
	257	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
d8c76e6f	258	inc_nlink(inode);
1da177e4 LT	259	atomic_inc(&inode->i_count);
	260	dget(dentry);
	261	d_instantiate(dentry, inode);
	262	return 0;
	263	}
	264
	265	static inline int simple_positive(struct dentry *dentry)
	266	{
	267	return dentry->d_inode && !d_unhashed(dentry);
	268	}
	269
	270	int simple_empty(struct dentry *dentry)
	271	{
	272	struct dentry *child;
	273	int ret = 0;
	274
	275	spin_lock(&dcache_lock);
5160ee6f	276	list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
1da177e4 LT	277	if (simple_positive(child))
	278	goto out;
	279	ret = 1;
	280	out:
	281	spin_unlock(&dcache_lock);
	282	return ret;
	283	}
	284
	285	int simple_unlink(struct inode dir, struct dentry dentry)
	286	{
	287	struct inode *inode = dentry->d_inode;
	288
	289	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
9a53c3a7	290	drop_nlink(inode);
1da177e4 LT	291	dput(dentry);
	292	return 0;
	293	}
	294
	295	int simple_rmdir(struct inode dir, struct dentry dentry)
	296	{
	297	if (!simple_empty(dentry))
	298	return -ENOTEMPTY;
	299
9a53c3a7	300	drop_nlink(dentry->d_inode);
1da177e4	301	simple_unlink(dir, dentry);
9a53c3a7	302	drop_nlink(dir);
1da177e4 LT	303	return 0;
	304	}
	305
	306	int simple_rename(struct inode old_dir, struct dentry old_dentry,
	307	struct inode new_dir, struct dentry new_dentry)
	308	{
	309	struct inode *inode = old_dentry->d_inode;
	310	int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
	311
	312	if (!simple_empty(new_dentry))
	313	return -ENOTEMPTY;
	314
	315	if (new_dentry->d_inode) {
	316	simple_unlink(new_dir, new_dentry);
	317	if (they_are_dirs)
9a53c3a7	318	drop_nlink(old_dir);
1da177e4	319	} else if (they_are_dirs) {
9a53c3a7	320	drop_nlink(old_dir);
d8c76e6f	321	inc_nlink(new_dir);
1da177e4 LT	322	}
	323
	324	old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
	325	new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
	326
	327	return 0;
	328	}
	329
	330	int simple_readpage(struct file file, struct page page)
	331	{
c0d92cbc	332	clear_highpage(page);
1da177e4 LT	333	flush_dcache_page(page);
1da177e4 LT	334	SetPageUptodate(page);
1da177e4 LT	335	unlock_page(page);
	336	return 0;
	337	}
	338
	339	int simple_prepare_write(struct file file, struct page page,
	340	unsigned from, unsigned to)
	341	{
	342	if (!PageUptodate(page)) {
	343	if (to - from != PAGE_CACHE_SIZE) {
	344	void *kaddr = kmap_atomic(page, KM_USER0);
	345	memset(kaddr, 0, from);
	346	memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
	347	flush_dcache_page(page);
	348	kunmap_atomic(kaddr, KM_USER0);
	349	}
1da177e4 LT	350	}
	351	return 0;
	352	}
	353
afddba49 NP	354	int simple_write_begin(struct file file, struct address_space mapping,
	355	loff_t pos, unsigned len, unsigned flags,
	356	struct page pagep, void fsdata)
	357	{
	358	struct page *page;
	359	pgoff_t index;
	360	unsigned from;
	361
	362	index = pos >> PAGE_CACHE_SHIFT;
	363	from = pos & (PAGE_CACHE_SIZE - 1);
	364
	365	page = __grab_cache_page(mapping, index);
	366	if (!page)
	367	return -ENOMEM;
	368
	369	*pagep = page;
	370
	371	return simple_prepare_write(file, page, from, from+len);
	372	}
	373
4a239427 AB	374	static int simple_commit_write(struct file file, struct page page,
4a239427 AB	375	unsigned from, unsigned to)
1da177e4 LT	376	{
	377	struct inode *inode = page->mapping->host;
	378	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
	379
955eff5a NP	380	if (!PageUptodate(page))
955eff5a NP	381	SetPageUptodate(page);
1da177e4 LT	382	/*
1da177e4 LT	383	* No need to use i_size_read() here, the i_size
1b1dcc1b	384	* cannot change under us because we hold the i_mutex.
1da177e4 LT	385	*/
	386	if (pos > inode->i_size)
	387	i_size_write(inode, pos);
	388	set_page_dirty(page);
	389	return 0;
	390	}
	391
afddba49 NP	392	int simple_write_end(struct file file, struct address_space mapping,
	393	loff_t pos, unsigned len, unsigned copied,
	394	struct page page, void fsdata)
	395	{
	396	unsigned from = pos & (PAGE_CACHE_SIZE - 1);
	397
	398	/* zero the stale part of the page if we did a short copy */
	399	if (copied < len) {
	400	void *kaddr = kmap_atomic(page, KM_USER0);
	401	memset(kaddr + from + copied, 0, len - copied);
	402	flush_dcache_page(page);
	403	kunmap_atomic(kaddr, KM_USER0);
	404	}
	405
	406	simple_commit_write(file, page, from, from+copied);
	407
	408	unlock_page(page);
	409	page_cache_release(page);
	410
	411	return copied;
	412	}
	413
1a1c9bb4 JL	414	/*
	415	* the inodes created here are not hashed. If you use iunique to generate
	416	* unique inode values later for this filesystem, then you must take care
	417	* to pass it an appropriate max_reserved value to avoid collisions.
	418	*/
1da177e4 LT	419	int simple_fill_super(struct super_block s, int magic, struct tree_descr files)
1da177e4 LT	420	{
1da177e4 LT	421	struct inode *inode;
	422	struct dentry *root;
	423	struct dentry *dentry;
	424	int i;
	425
	426	s->s_blocksize = PAGE_CACHE_SIZE;
	427	s->s_blocksize_bits = PAGE_CACHE_SHIFT;
	428	s->s_magic = magic;
759b9775	429	s->s_op = &simple_super_operations;
1da177e4 LT	430	s->s_time_gran = 1;
	431
	432	inode = new_inode(s);
	433	if (!inode)
	434	return -ENOMEM;
1a1c9bb4 JL	435	/*
	436	* because the root inode is 1, the files array must not contain an
	437	* entry at index 1
	438	*/
	439	inode->i_ino = 1;
1da177e4 LT	440	inode->i_mode = S_IFDIR \| 0755;
1da177e4 LT	441	inode->i_uid = inode->i_gid = 0;
1da177e4 LT	442	inode->i_blocks = 0;
	443	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	444	inode->i_op = &simple_dir_inode_operations;
	445	inode->i_fop = &simple_dir_operations;
7656f328	446	inode->i_nlink = 2;
1da177e4 LT	447	root = d_alloc_root(inode);
	448	if (!root) {
	449	iput(inode);
	450	return -ENOMEM;
	451	}
	452	for (i = 0; !files->name \|\| files->name[0]; i++, files++) {
	453	if (!files->name)
	454	continue;
1a1c9bb4 JL	455
	456	/* warn if it tries to conflict with the root inode */
	457	if (unlikely(i == 1))
	458	printk(KERN_WARNING "%s: %s passed in a files array"
	459	"with an index of 1!\n", __func__,
	460	s->s_type->name);
	461
1da177e4 LT	462	dentry = d_alloc_name(root, files->name);
	463	if (!dentry)
	464	goto out;
	465	inode = new_inode(s);
	466	if (!inode)
	467	goto out;
	468	inode->i_mode = S_IFREG \| files->mode;
	469	inode->i_uid = inode->i_gid = 0;
1da177e4 LT	470	inode->i_blocks = 0;
	471	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	472	inode->i_fop = files->ops;
	473	inode->i_ino = i;
	474	d_add(dentry, inode);
	475	}
	476	s->s_root = root;
	477	return 0;
	478	out:
	479	d_genocide(root);
	480	dput(root);
	481	return -ENOMEM;
	482	}
	483
	484	static DEFINE_SPINLOCK(pin_fs_lock);
	485
1f5ce9e9	486	int simple_pin_fs(struct file_system_type type, struct vfsmount mount, int count)
1da177e4 LT	487	{
	488	struct vfsmount *mnt = NULL;
	489	spin_lock(&pin_fs_lock);
	490	if (unlikely(!*mount)) {
	491	spin_unlock(&pin_fs_lock);
1f5ce9e9	492	mnt = vfs_kern_mount(type, 0, type->name, NULL);
1da177e4 LT	493	if (IS_ERR(mnt))
	494	return PTR_ERR(mnt);
	495	spin_lock(&pin_fs_lock);
	496	if (!*mount)
	497	*mount = mnt;
	498	}
	499	mntget(*mount);
	500	++*count;
	501	spin_unlock(&pin_fs_lock);
	502	mntput(mnt);
	503	return 0;
	504	}
	505
	506	void simple_release_fs(struct vfsmount *mount, int count)
	507	{
	508	struct vfsmount *mnt;
	509	spin_lock(&pin_fs_lock);
	510	mnt = *mount;
	511	if (!--*count)
	512	*mount = NULL;
	513	spin_unlock(&pin_fs_lock);
	514	mntput(mnt);
	515	}
	516
	517	ssize_t simple_read_from_buffer(void __user to, size_t count, loff_t ppos,
	518	const void *from, size_t available)
	519	{
	520	loff_t pos = *ppos;
	521	if (pos < 0)
	522	return -EINVAL;
	523	if (pos >= available)
	524	return 0;
	525	if (count > available - pos)
	526	count = available - pos;
	527	if (copy_to_user(to, from + pos, count))
	528	return -EFAULT;
	529	*ppos = pos + count;
	530	return count;
	531	}
	532
	533	/*
	534	* Transaction based IO.
	535	* The file expects a single write which triggers the transaction, and then
	536	* possibly a read which collects the result - which is stored in a
	537	* file-local buffer.
	538	*/
	539	char simple_transaction_get(struct file file, const char __user *buf, size_t size)
	540	{
	541	struct simple_transaction_argresp *ar;
	542	static DEFINE_SPINLOCK(simple_transaction_lock);
	543
	544	if (size > SIMPLE_TRANSACTION_LIMIT - 1)
	545	return ERR_PTR(-EFBIG);
	546
	547	ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
	548	if (!ar)
	549	return ERR_PTR(-ENOMEM);
	550
	551	spin_lock(&simple_transaction_lock);
	552
	553	/* only one write allowed per open */
	554	if (file->private_data) {
	555	spin_unlock(&simple_transaction_lock);
	556	free_page((unsigned long)ar);
557	return ERR_PTR(-EBUSY);
558	}
559
560	file->private_data = ar;
561
562	spin_unlock(&simple_transaction_lock);
563
564	if (copy_from_user(ar->data, buf, size))
565	return ERR_PTR(-EFAULT);
566
567	return ar->data;
568	}
569
570	ssize_t simple_transaction_read(struct file file, char __user buf, size_t size, loff_t *pos)
571	{
572	struct simple_transaction_argresp *ar = file->private_data;
573
574	if (!ar)
575	return 0;
576	return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
577	}
578
579	int simple_transaction_release(struct inode inode, struct file file)
580	{
581	free_page((unsigned long)file->private_data);
582	return 0;
583	}
584
acaefc25 AB	585	/* Simple attribute files */
	586
	587	struct simple_attr {
	588	u64 (get)(void );
	589	void (set)(void , u64);
	590	char get_buf[24]; /* enough to store a u64 and "\n\0" */
	591	char set_buf[24];
	592	void *data;
	593	const char fmt; / format for read operation */
7cf34c76	594	struct mutex mutex; /* protects access to these buffers */
acaefc25 AB	595	};
	596
	597	/* simple_attr_open is called by an actual attribute open file operation
	598	* to set the attribute specific access operations. */
	599	int simple_attr_open(struct inode inode, struct file file,
	600	u64 (get)(void ), void (set)(void , u64),
	601	const char *fmt)
	602	{
	603	struct simple_attr *attr;
	604
	605	attr = kmalloc(sizeof(*attr), GFP_KERNEL);
	606	if (!attr)
	607	return -ENOMEM;
	608
	609	attr->get = get;
	610	attr->set = set;
8e18e294	611	attr->data = inode->i_private;
acaefc25	612	attr->fmt = fmt;
7cf34c76	613	mutex_init(&attr->mutex);
acaefc25 AB	614
	615	file->private_data = attr;
	616
	617	return nonseekable_open(inode, file);
	618	}
	619
	620	int simple_attr_close(struct inode inode, struct file file)
	621	{
	622	kfree(file->private_data);
	623	return 0;
	624	}
	625
	626	/* read from the buffer that is filled with the get function */
	627	ssize_t simple_attr_read(struct file file, char __user buf,
	628	size_t len, loff_t *ppos)
	629	{
	630	struct simple_attr *attr;
	631	size_t size;
	632	ssize_t ret;
	633
	634	attr = file->private_data;
	635
	636	if (!attr->get)
	637	return -EACCES;
	638
7cf34c76	639	mutex_lock(&attr->mutex);
acaefc25 AB	640	if (ppos) / continued read */
	641	size = strlen(attr->get_buf);
	642	else /* first read */
	643	size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
	644	attr->fmt,
	645	(unsigned long long)attr->get(attr->data));
	646
	647	ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
7cf34c76	648	mutex_unlock(&attr->mutex);
acaefc25 AB	649	return ret;
	650	}
	651
	652	/* interpret the buffer as a number to call the set function with */
	653	ssize_t simple_attr_write(struct file file, const char __user buf,
	654	size_t len, loff_t *ppos)
	655	{
	656	struct simple_attr *attr;
	657	u64 val;
	658	size_t size;
	659	ssize_t ret;
	660
	661	attr = file->private_data;
	662
	663	if (!attr->set)
	664	return -EACCES;
	665
7cf34c76	666	mutex_lock(&attr->mutex);
acaefc25 AB	667	ret = -EFAULT;
	668	size = min(sizeof(attr->set_buf) - 1, len);
	669	if (copy_from_user(attr->set_buf, buf, size))
	670	goto out;
	671
	672	ret = len; /* claim we got the whole input */
	673	attr->set_buf[size] = '\0';
	674	val = simple_strtol(attr->set_buf, NULL, 0);
	675	attr->set(attr->data, val);
	676	out:
7cf34c76	677	mutex_unlock(&attr->mutex);
acaefc25 AB	678	return ret;
	679	}
	680
1da177e4 LT	681	EXPORT_SYMBOL(dcache_dir_close);
	682	EXPORT_SYMBOL(dcache_dir_lseek);
	683	EXPORT_SYMBOL(dcache_dir_open);
	684	EXPORT_SYMBOL(dcache_readdir);
	685	EXPORT_SYMBOL(generic_read_dir);
	686	EXPORT_SYMBOL(get_sb_pseudo);
afddba49 NP	687	EXPORT_SYMBOL(simple_write_begin);
afddba49 NP	688	EXPORT_SYMBOL(simple_write_end);
1da177e4 LT	689	EXPORT_SYMBOL(simple_dir_inode_operations);
	690	EXPORT_SYMBOL(simple_dir_operations);
	691	EXPORT_SYMBOL(simple_empty);
	692	EXPORT_SYMBOL(d_alloc_name);
	693	EXPORT_SYMBOL(simple_fill_super);
	694	EXPORT_SYMBOL(simple_getattr);
	695	EXPORT_SYMBOL(simple_link);
	696	EXPORT_SYMBOL(simple_lookup);
	697	EXPORT_SYMBOL(simple_pin_fs);
	698	EXPORT_SYMBOL(simple_prepare_write);
	699	EXPORT_SYMBOL(simple_readpage);
	700	EXPORT_SYMBOL(simple_release_fs);
	701	EXPORT_SYMBOL(simple_rename);
	702	EXPORT_SYMBOL(simple_rmdir);
	703	EXPORT_SYMBOL(simple_statfs);
	704	EXPORT_SYMBOL(simple_sync_file);
	705	EXPORT_SYMBOL(simple_unlink);
	706	EXPORT_SYMBOL(simple_read_from_buffer);
	707	EXPORT_SYMBOL(simple_transaction_get);
	708	EXPORT_SYMBOL(simple_transaction_read);
	709	EXPORT_SYMBOL(simple_transaction_release);
acaefc25 AB	710	EXPORT_SYMBOL_GPL(simple_attr_open);
	711	EXPORT_SYMBOL_GPL(simple_attr_close);
	712	EXPORT_SYMBOL_GPL(simple_attr_read);
	713	EXPORT_SYMBOL_GPL(simple_attr_write);