rpc_pipe.c

linux 内核源代码

void rpc_put_mount(void)
{
	simple_release_fs(&rpc_mount, &rpc_mount_count);
}

static int rpc_delete_dentry(struct dentry *dentry)
{
	return 1;
}

static struct dentry_operations rpc_dentry_operations = {
	.d_delete = rpc_delete_dentry,
};

static int
rpc_lookup_parent(char *path, struct nameidata *nd)
{
	struct vfsmount *mnt;

	if (path[0] == '\0')
		return -ENOENT;

	mnt = rpc_get_mount();
	if (IS_ERR(mnt)) {
		printk(KERN_WARNING "%s: %s failed to mount "
			       "pseudofilesystem \n", __FILE__, __FUNCTION__);
		return PTR_ERR(mnt);
	}

	if (vfs_path_lookup(mnt->mnt_root, mnt, path, LOOKUP_PARENT, nd)) {
		printk(KERN_WARNING "%s: %s failed to find path %s\n",
				__FILE__, __FUNCTION__, path);
		rpc_put_mount();
		return -ENOENT;
	}
	return 0;
}

static void
rpc_release_path(struct nameidata *nd)
{
	path_release(nd);
	rpc_put_mount();
}

static struct inode *
rpc_get_inode(struct super_block *sb, int mode)
{
	struct inode *inode = new_inode(sb);
	if (!inode)
		return NULL;
	inode->i_mode = mode;
	inode->i_uid = inode->i_gid = 0;
	inode->i_blocks = 0;
	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	switch(mode & S_IFMT) {
		case S_IFDIR:
			inode->i_fop = &simple_dir_operations;
			inode->i_op = &simple_dir_inode_operations;
			inc_nlink(inode);
		default:
			break;
	}
	return inode;
}

/*
 * FIXME: This probably has races.
 */
static void
rpc_depopulate(struct dentry *parent, int start, int eof)
{
	struct inode *dir = parent->d_inode;
	struct list_head *pos, *next;
	struct dentry *dentry, *dvec[10];
	int n = 0;

	mutex_lock_nested(&dir->i_mutex, I_MUTEX_CHILD);
repeat:
	spin_lock(&dcache_lock);
	list_for_each_safe(pos, next, &parent->d_subdirs) {
		dentry = list_entry(pos, struct dentry, d_u.d_child);
		if (!dentry->d_inode ||
				dentry->d_inode->i_ino < start ||
				dentry->d_inode->i_ino >= eof)
			continue;
		spin_lock(&dentry->d_lock);
		if (!d_unhashed(dentry)) {
			dget_locked(dentry);
			__d_drop(dentry);
			spin_unlock(&dentry->d_lock);
			dvec[n++] = dentry;
			if (n == ARRAY_SIZE(dvec))
				break;
		} else
			spin_unlock(&dentry->d_lock);
	}
	spin_unlock(&dcache_lock);
	if (n) {
		do {
			dentry = dvec[--n];
			if (S_ISREG(dentry->d_inode->i_mode))
				simple_unlink(dir, dentry);
			else if (S_ISDIR(dentry->d_inode->i_mode))
				simple_rmdir(dir, dentry);
			d_delete(dentry);
			dput(dentry);
		} while (n);
		goto repeat;
	}
	mutex_unlock(&dir->i_mutex);
}

static int
rpc_populate(struct dentry *parent,
		struct rpc_filelist *files,
		int start, int eof)
{
	struct inode *inode, *dir = parent->d_inode;
	void *private = RPC_I(dir)->private;
	struct dentry *dentry;
	int mode, i;

	mutex_lock(&dir->i_mutex);
	for (i = start; i < eof; i++) {
		dentry = d_alloc_name(parent, files[i].name);
		if (!dentry)
			goto out_bad;
		dentry->d_op = &rpc_dentry_operations;
		mode = files[i].mode;
		inode = rpc_get_inode(dir->i_sb, mode);
		if (!inode) {
			dput(dentry);
			goto out_bad;
		}
		inode->i_ino = i;
		if (files[i].i_fop)
			inode->i_fop = files[i].i_fop;
		if (private)
			rpc_inode_setowner(inode, private);
		if (S_ISDIR(mode))
			inc_nlink(dir);
		d_add(dentry, inode);
		fsnotify_create(dir, dentry);
	}
	mutex_unlock(&dir->i_mutex);
	return 0;
out_bad:
	mutex_unlock(&dir->i_mutex);
	printk(KERN_WARNING "%s: %s failed to populate directory %s\n",
			__FILE__, __FUNCTION__, parent->d_name.name);
	return -ENOMEM;
}

static int
__rpc_mkdir(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode;

	inode = rpc_get_inode(dir->i_sb, S_IFDIR | S_IRUGO | S_IXUGO);
	if (!inode)
		goto out_err;
	inode->i_ino = iunique(dir->i_sb, 100);
	d_instantiate(dentry, inode);
	inc_nlink(dir);
	fsnotify_mkdir(dir, dentry);
	return 0;
out_err:
	printk(KERN_WARNING "%s: %s failed to allocate inode for dentry %s\n",
			__FILE__, __FUNCTION__, dentry->d_name.name);
	return -ENOMEM;
}

static int
__rpc_rmdir(struct inode *dir, struct dentry *dentry)
{
	int error;
	error = simple_rmdir(dir, dentry);
	if (!error)
		d_delete(dentry);
	return error;
}

static struct dentry *
rpc_lookup_create(struct dentry *parent, const char *name, int len, int exclusive)
{
	struct inode *dir = parent->d_inode;
	struct dentry *dentry;

	mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
	dentry = lookup_one_len(name, parent, len);
	if (IS_ERR(dentry))
		goto out_err;
	if (!dentry->d_inode)
		dentry->d_op = &rpc_dentry_operations;
	else if (exclusive) {
		dput(dentry);
		dentry = ERR_PTR(-EEXIST);
		goto out_err;
	}
	return dentry;
out_err:
	mutex_unlock(&dir->i_mutex);
	return dentry;
}

static struct dentry *
rpc_lookup_negative(char *path, struct nameidata *nd)
{
	struct dentry *dentry;
	int error;

	if ((error = rpc_lookup_parent(path, nd)) != 0)
		return ERR_PTR(error);
	dentry = rpc_lookup_create(nd->dentry, nd->last.name, nd->last.len, 1);
	if (IS_ERR(dentry))
		rpc_release_path(nd);
	return dentry;
}


struct dentry *
rpc_mkdir(char *path, struct rpc_clnt *rpc_client)
{
	struct nameidata nd;
	struct dentry *dentry;
	struct inode *dir;
	int error;

	dentry = rpc_lookup_negative(path, &nd);
	if (IS_ERR(dentry))
		return dentry;
	dir = nd.dentry->d_inode;
	if ((error = __rpc_mkdir(dir, dentry)) != 0)
		goto err_dput;
	RPC_I(dentry->d_inode)->private = rpc_client;
	error = rpc_populate(dentry, authfiles,
			RPCAUTH_info, RPCAUTH_EOF);
	if (error)
		goto err_depopulate;
	dget(dentry);
out:
	mutex_unlock(&dir->i_mutex);
	rpc_release_path(&nd);
	return dentry;
err_depopulate:
	rpc_depopulate(dentry, RPCAUTH_info, RPCAUTH_EOF);
	__rpc_rmdir(dir, dentry);
err_dput:
	dput(dentry);
	printk(KERN_WARNING "%s: %s() failed to create directory %s (errno = %d)\n",
			__FILE__, __FUNCTION__, path, error);
	dentry = ERR_PTR(error);
	goto out;
}

int
rpc_rmdir(struct dentry *dentry)
{
	struct dentry *parent;
	struct inode *dir;
	int error;

	parent = dget_parent(dentry);
	dir = parent->d_inode;
	mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
	rpc_depopulate(dentry, RPCAUTH_info, RPCAUTH_EOF);
	error = __rpc_rmdir(dir, dentry);
	dput(dentry);
	mutex_unlock(&dir->i_mutex);
	dput(parent);
	return error;
}

struct dentry *
rpc_mkpipe(struct dentry *parent, const char *name, void *private, struct rpc_pipe_ops *ops, int flags)
{
	struct dentry *dentry;
	struct inode *dir, *inode;
	struct rpc_inode *rpci;

	dentry = rpc_lookup_create(parent, name, strlen(name), 0);
	if (IS_ERR(dentry))
		return dentry;
	dir = parent->d_inode;
	if (dentry->d_inode) {
		rpci = RPC_I(dentry->d_inode);
		if (rpci->private != private ||
				rpci->ops != ops ||
				rpci->flags != flags) {
			dput (dentry);
			dentry = ERR_PTR(-EBUSY);
		}
		rpci->nkern_readwriters++;
		goto out;
	}
	inode = rpc_get_inode(dir->i_sb, S_IFIFO | S_IRUSR | S_IWUSR);
	if (!inode)
		goto err_dput;
	inode->i_ino = iunique(dir->i_sb, 100);
	inode->i_fop = &rpc_pipe_fops;
	d_instantiate(dentry, inode);
	rpci = RPC_I(inode);
	rpci->private = private;
	rpci->flags = flags;
	rpci->ops = ops;
	rpci->nkern_readwriters = 1;
	fsnotify_create(dir, dentry);
	dget(dentry);
out:
	mutex_unlock(&dir->i_mutex);
	return dentry;
err_dput:
	dput(dentry);
	dentry = ERR_PTR(-ENOMEM);
	printk(KERN_WARNING "%s: %s() failed to create pipe %s/%s (errno = %d)\n",
			__FILE__, __FUNCTION__, parent->d_name.name, name,
			-ENOMEM);
	goto out;
}

int
rpc_unlink(struct dentry *dentry)
{
	struct dentry *parent;
	struct inode *dir;
	int error = 0;

	parent = dget_parent(dentry);
	dir = parent->d_inode;
	mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
	if (--RPC_I(dentry->d_inode)->nkern_readwriters == 0) {
		rpc_close_pipes(dentry->d_inode);
		error = simple_unlink(dir, dentry);
		if (!error)
			d_delete(dentry);
	}
	dput(dentry);
	mutex_unlock(&dir->i_mutex);
	dput(parent);
	return error;
}

/*
 * populate the filesystem
 */
static struct super_operations s_ops = {
	.alloc_inode	= rpc_alloc_inode,
	.destroy_inode	= rpc_destroy_inode,
	.statfs		= simple_statfs,
};

#define RPCAUTH_GSSMAGIC 0x67596969

static int
rpc_fill_super(struct super_block *sb, void *data, int silent)
{
	struct inode *inode;
	struct dentry *root;

	sb->s_blocksize = PAGE_CACHE_SIZE;
	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	sb->s_magic = RPCAUTH_GSSMAGIC;
	sb->s_op = &s_ops;
	sb->s_time_gran = 1;

	inode = rpc_get_inode(sb, S_IFDIR | 0755);
	if (!inode)
		return -ENOMEM;
	root = d_alloc_root(inode);
	if (!root) {
		iput(inode);
		return -ENOMEM;
	}
	if (rpc_populate(root, files, RPCAUTH_Root + 1, RPCAUTH_RootEOF))
		goto out;
	sb->s_root = root;
	return 0;
out:
	d_genocide(root);
	dput(root);
	return -ENOMEM;
}

static int
rpc_get_sb(struct file_system_type *fs_type,
		int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
	return get_sb_single(fs_type, flags, data, rpc_fill_super, mnt);
}

static struct file_system_type rpc_pipe_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "rpc_pipefs",
	.get_sb		= rpc_get_sb,
	.kill_sb	= kill_litter_super,
};

static void
init_once(struct kmem_cache * cachep, void *foo)
{
	struct rpc_inode *rpci = (struct rpc_inode *) foo;

	inode_init_once(&rpci->vfs_inode);
	rpci->private = NULL;
	rpci->nreaders = 0;
	rpci->nwriters = 0;
	INIT_LIST_HEAD(&rpci->in_upcall);
	INIT_LIST_HEAD(&rpci->in_downcall);
	INIT_LIST_HEAD(&rpci->pipe);
	rpci->pipelen = 0;
	init_waitqueue_head(&rpci->waitq);
	INIT_DELAYED_WORK(&rpci->queue_timeout,
			    rpc_timeout_upcall_queue);
	rpci->ops = NULL;
}

int register_rpc_pipefs(void)
{
	int err;

	rpc_inode_cachep = kmem_cache_create("rpc_inode_cache",
				sizeof(struct rpc_inode),
				0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
						SLAB_MEM_SPREAD),
				init_once);
	if (!rpc_inode_cachep)
		return -ENOMEM;
	err = register_filesystem(&rpc_pipe_fs_type);
	if (err) {
		kmem_cache_destroy(rpc_inode_cachep);
		return err;
	}

	return 0;
}

void unregister_rpc_pipefs(void)
{
	kmem_cache_destroy(rpc_inode_cachep);
	unregister_filesystem(&rpc_pipe_fs_type);
}