base.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 2,003 行 · 第 1/5 页

 *	devfs_mk_symlink Create a symbolic link in the devfs namespace.
 *	@from: The name of the entry.
 *	@to: Name of the destination
 *
 *	Returns 0 on success, else a negative error code is returned.
 */

int devfs_mk_symlink(const char *from, const char *to)
{
	devfs_handle_t de;
	int err;

	err = devfs_do_symlink(NULL, from, to, &de);
	if (!err) {
		de->vfs = TRUE;
		devfsd_notify(de, DEVFSD_NOTIFY_REGISTERED);
	}

	return err;
}

/**
 *	devfs_mk_dir - Create a directory in the devfs namespace.
 *		new name is relative to the root of the devfs.
 *	@fmt: The name of the entry.
 *
 *	Use of this function is optional. The devfs_register() function
 *	will automatically create intermediate directories as needed. This function
 *	is provided for efficiency reasons, as it provides a handle to a directory.
 *	On failure %NULL is returned.
 */

int devfs_mk_dir(const char *fmt, ...)
{
	struct devfs_entry *dir = NULL, *de = NULL, *old;
	char buf[64];
	va_list args;
	int error, n;

	va_start(args, fmt);
	n = vsnprintf(buf, 64, fmt, args);
	if (n >= 64 || !buf[0]) {
		printk(KERN_WARNING "%s: invalid argument.", __FUNCTION__);
		return -EINVAL;
	}

	de = _devfs_prepare_leaf(&dir, buf, MODE_DIR);
	if (!de) {
		PRINTK("(%s): could not prepare leaf\n", buf);
		return -EINVAL;
	}

	error = _devfs_append_entry(dir, de, &old);
	if (error == -EEXIST && S_ISDIR(old->mode)) {
		/*
		 * devfs_mk_dir() of an already-existing directory will
		 * return success.
		 */
		error = 0;
		goto out_put;
	} else if (error) {
		PRINTK("(%s): could not append to dir: %p \"%s\"\n",
		       buf, dir, dir->name);
		devfs_put(old);
		goto out_put;
	}

	devfsd_notify(de, DEVFSD_NOTIFY_REGISTERED);

      out_put:
	devfs_put(dir);
	return error;
}

void devfs_remove(const char *fmt, ...)
{
	char buf[64];
	va_list args;
	int n;

	va_start(args, fmt);
	n = vsnprintf(buf, sizeof(buf), fmt, args);
	if (n < sizeof(buf) && buf[0]) {
		devfs_handle_t de = _devfs_find_entry(NULL, buf, 0);

		if (!de) {
			printk(KERN_ERR "%s: %s not found, cannot remove\n",
			       __FUNCTION__, buf);
			dump_stack();
			return;
		}

		write_lock(&de->parent->u.dir.lock);
		_devfs_unregister(de->parent, de);
		devfs_put(de);
		devfs_put(de);
	}
}

/**
 *	devfs_generate_path - Generate a pathname for an entry, relative to the devfs root.
 *	@de: The devfs entry.
 *	@path: The buffer to write the pathname to. The pathname and '\0'
 *		terminator will be written at the end of the buffer.
 *	@buflen: The length of the buffer.
 *
 *	Returns the offset in the buffer where the pathname starts on success,
 *	else a negative error code.
 */

static int devfs_generate_path(devfs_handle_t de, char *path, int buflen)
{
	int pos;
#define NAMEOF(de) ( (de)->mode ? (de)->name : (de)->u.name )

	if (de == NULL)
		return -EINVAL;
	VERIFY_ENTRY(de);
	if (de->namelen >= buflen)
		return -ENAMETOOLONG;	/*  Must be first       */
	path[buflen - 1] = '\0';
	if (de->parent == NULL)
		return buflen - 1;	/*  Don't prepend root  */
	pos = buflen - de->namelen - 1;
	memcpy(path + pos, NAMEOF(de), de->namelen);
	for (de = de->parent; de->parent != NULL; de = de->parent) {
		if (pos - de->namelen - 1 < 0)
			return -ENAMETOOLONG;
		path[--pos] = '/';
		pos -= de->namelen;
		memcpy(path + pos, NAMEOF(de), de->namelen);
	}
	return pos;
}				/*  End Function devfs_generate_path  */

/**
 *	devfs_setup - Process kernel boot options.
 *	@str: The boot options after the "devfs=".
 */

static int __init devfs_setup(char *str)
{
	static struct {
		char *name;
		unsigned int mask;
		unsigned int *opt;
	} devfs_options_tab[] __initdata = {
#ifdef CONFIG_DEVFS_DEBUG
		{
		"dall", DEBUG_ALL, &devfs_debug_init}, {
		"dmod", DEBUG_MODULE_LOAD, &devfs_debug_init}, {
		"dreg", DEBUG_REGISTER, &devfs_debug_init}, {
		"dunreg", DEBUG_UNREGISTER, &devfs_debug_init}, {
		"dfree", DEBUG_FREE, &devfs_debug_init}, {
		"diget", DEBUG_I_GET, &devfs_debug_init}, {
		"dchange", DEBUG_SET_FLAGS, &devfs_debug_init}, {
		"dsread", DEBUG_S_READ, &devfs_debug_init}, {
		"dichange", DEBUG_I_CHANGE, &devfs_debug_init}, {
		"dimknod", DEBUG_I_MKNOD, &devfs_debug_init}, {
		"dilookup", DEBUG_I_LOOKUP, &devfs_debug_init}, {
		"diunlink", DEBUG_I_UNLINK, &devfs_debug_init},
#endif				/*  CONFIG_DEVFS_DEBUG  */
		{
		"mount", OPTION_MOUNT, &boot_options}, {
		NULL, 0, NULL}
	};

	while ((*str != '\0') && !isspace(*str)) {
		int i, found = 0, invert = 0;

		if (strncmp(str, "no", 2) == 0) {
			invert = 1;
			str += 2;
		}
		for (i = 0; devfs_options_tab[i].name != NULL; i++) {
			int len = strlen(devfs_options_tab[i].name);

			if (strncmp(str, devfs_options_tab[i].name, len) == 0) {
				if (invert)
					*devfs_options_tab[i].opt &=
					    ~devfs_options_tab[i].mask;
				else
					*devfs_options_tab[i].opt |=
					    devfs_options_tab[i].mask;
				str += len;
				found = 1;
				break;
			}
		}
		if (!found)
			return 0;	/*  No match         */
		if (*str != ',')
			return 0;	/*  No more options  */
		++str;
	}
	return 1;
}				/*  End Function devfs_setup  */

__setup("devfs=", devfs_setup);

EXPORT_SYMBOL(devfs_mk_symlink);
EXPORT_SYMBOL(devfs_mk_dir);
EXPORT_SYMBOL(devfs_remove);

/**
 *	try_modload - Notify devfsd of an inode lookup by a non-devfsd process.
 *	@parent: The parent devfs entry.
 *	@fs_info: The filesystem info.
 *	@name: The device name.
 *	@namelen: The number of characters in @name.
 *	@buf: A working area that will be used. This must not go out of scope
 *            until devfsd is idle again.
 *
 *	Returns 0 on success (event was queued), else a negative error code.
 */

static int try_modload(struct devfs_entry *parent, struct fs_info *fs_info,
		       const char *name, unsigned namelen,
		       struct devfs_entry *buf)
{
	if (!(fs_info->devfsd_event_mask & (1 << DEVFSD_NOTIFY_LOOKUP)))
		return -ENOENT;
	if (is_devfsd_or_child(fs_info))
		return -ENOENT;
	memset(buf, 0, sizeof *buf);
	atomic_set(&buf->refcount, 1);
	buf->parent = parent;
	buf->namelen = namelen;
	buf->u.name = name;
	WRITE_ENTRY_MAGIC(buf, MAGIC_VALUE);
	if (!devfsd_notify_de(buf, DEVFSD_NOTIFY_LOOKUP, 0,
			      current->euid, current->egid, fs_info))
		return -ENOENT;
	/*  Possible success: event has been queued  */
	return 0;
}				/*  End Function try_modload  */

/*  Superblock operations follow  */

static struct inode_operations devfs_iops;
static struct inode_operations devfs_dir_iops;
static struct file_operations devfs_fops;
static struct file_operations devfs_dir_fops;
static struct inode_operations devfs_symlink_iops;

static int devfs_notify_change(struct dentry *dentry, struct iattr *iattr)
{
	int retval;
	struct devfs_entry *de;
	struct inode *inode = dentry->d_inode;
	struct fs_info *fs_info = inode->i_sb->s_fs_info;

	de = get_devfs_entry_from_vfs_inode(inode);
	if (de == NULL)
		return -ENODEV;
	retval = inode_change_ok(inode, iattr);
	if (retval != 0)
		return retval;
	retval = inode_setattr(inode, iattr);
	if (retval != 0)
		return retval;
	DPRINTK(DEBUG_I_CHANGE, "(%d): VFS inode: %p  devfs_entry: %p\n",
		(int)inode->i_ino, inode, de);
	DPRINTK(DEBUG_I_CHANGE, "():   mode: 0%o  uid: %d  gid: %d\n",
		(int)inode->i_mode, (int)inode->i_uid, (int)inode->i_gid);
	/*  Inode is not on hash chains, thus must save permissions here rather
	   than in a write_inode() method  */
	de->mode = inode->i_mode;
	de->inode.uid = inode->i_uid;
	de->inode.gid = inode->i_gid;
	de->inode.atime = inode->i_atime;
	de->inode.mtime = inode->i_mtime;
	de->inode.ctime = inode->i_ctime;
	if ((iattr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) &&
	    !is_devfsd_or_child(fs_info))
		devfsd_notify_de(de, DEVFSD_NOTIFY_CHANGE, inode->i_mode,
				 inode->i_uid, inode->i_gid, fs_info);
	return 0;
}				/*  End Function devfs_notify_change  */

static struct super_operations devfs_sops = {
	.drop_inode = generic_delete_inode,
	.statfs = simple_statfs,
};

/**
 *	_devfs_get_vfs_inode - Get a VFS inode.
 *	@sb: The super block.
 *	@de: The devfs inode.
 *	@dentry: The dentry to register with the devfs inode.
 *
 *	Returns the inode on success, else %NULL. An implicit devfs_get() is
 *       performed if the inode is created.
 */

static struct inode *_devfs_get_vfs_inode(struct super_block *sb,
					  struct devfs_entry *de,
					  struct dentry *dentry)
{
	struct inode *inode;

	if (de->prev == de)
		return NULL;	/*  Quick check to see if unhooked  */
	if ((inode = new_inode(sb)) == NULL) {
		PRINTK("(%s): new_inode() failed, de: %p\n", de->name, de);
		return NULL;
	}
	if (de->parent) {
		read_lock(&de->parent->u.dir.lock);
		if (de->prev != de)
			de->inode.dentry = dentry;	/*      Not unhooked  */
		read_unlock(&de->parent->u.dir.lock);
	} else
		de->inode.dentry = dentry;	/*  Root: no locking needed  */
	if (de->inode.dentry != dentry) {	/*  Must have been unhooked  */
		iput(inode);
		return NULL;
	}
	/* FIXME where is devfs_put? */
	inode->u.generic_ip = devfs_get(de);
	inode->i_ino = de->inode.ino;
	DPRINTK(DEBUG_I_GET, "(%d): VFS inode: %p  devfs_entry: %p\n",
		(int)inode->i_ino, inode, de);
	inode->i_blocks = 0;
	inode->i_blksize = FAKE_BLOCK_SIZE;
	inode->i_op = &devfs_iops;
	inode->i_mode = de->mode;
	if (S_ISDIR(de->mode)) {
		inode->i_op = &devfs_dir_iops;
		inode->i_fop = &devfs_dir_fops;
	} else if (S_ISLNK(de->mode)) {
		inode->i_op = &devfs_symlink_iops;
		inode->i_size = de->u.symlink.length;
	} else if (S_ISCHR(de->mode) || S_ISBLK(de->mode)) {
		init_special_inode(inode, de->mode, de->u.dev);
	} else if (S_ISFIFO(de->mode) || S_ISSOCK(de->mode)) {
		init_special_inode(inode, de->mode, 0);
	} else {
		PRINTK("(%s): unknown mode %o de: %p\n",
		       de->name, de->mode, de);
		iput(inode);
		devfs_put(de);
		return NULL;
	}

	inode->i_uid = de->inode.uid;
	inode->i_gid = de->inode.gid;
	inode->i_atime = de->inode.atime;
	inode->i_mtime = de->inode.mtime;
	inode->i_ctime = de->inode.ctime;
	DPRINTK(DEBUG_I_GET, "():   mode: 0%o  uid: %d  gid: %d\n",
		(int)inode->i_mode, (int)inode->i_uid, (int)inode->i_gid);
	return inode;
}				/*  End Function _devfs_get_vfs_inode  */

/*  File operations for device entries follow  */

static int devfs_readdir(struct file *file, void *dirent, filldir_t filldir)
{
	int err, count;
	int stored = 0;
	struct fs_info *fs_info;
	struct devfs_entry *parent, *de, *next = NULL;
	struct inode *inode = file->f_dentry->d_inode;

	fs_info = inode->i_sb->s_fs_info;
	parent = get_devfs_entry_from_vfs_inode(file->f_dentry->d_inode);
	if ((long)file->f_pos < 0)
		return -EINVAL;
	DPRINTK(DEBUG_F_READDIR, "(%s): fs_info: %p  pos: %ld\n",
		parent->name, fs_info, (long)file->f_pos);
	switch ((long)file->f_pos) {
	case 0:
		err = (*filldir) (dirent, "..", 2, file->f_pos,
				  parent_ino(file->f_dentry), DT_DIR);
		if (err == -EINVAL)
			break;
		if (err < 0)
			return err;
		file->f_pos++;
		++stored;
		/*  Fall through  */
	case 1:
		err =
		    (*filldir) (dirent, ".", 1, file->f_pos, inode->i_ino,
				DT_DIR);
		if (err == -EINVAL)
			break;
		if (err < 0)
			return err;
		file->f_pos++;
		++stored;
		/*  Fall through  */
	default:
		/*  Skip entries  */
		count = file->f_pos - 2;
		read_lock(&parent->u.dir.lock);
		for (de = parent->u.dir.first; de && (count > 0); de = de->next)