inode.c

linux 内核源代码

static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
{
	struct fuse_conn *fc = get_fuse_conn_super(mnt->mnt_sb);

	seq_printf(m, ",user_id=%u", fc->user_id);
	seq_printf(m, ",group_id=%u", fc->group_id);
	if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
		seq_puts(m, ",default_permissions");
	if (fc->flags & FUSE_ALLOW_OTHER)
		seq_puts(m, ",allow_other");
	if (fc->max_read != ~0)
		seq_printf(m, ",max_read=%u", fc->max_read);
	return 0;
}

static struct fuse_conn *new_conn(void)
{
	struct fuse_conn *fc;
	int err;

	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
	if (fc) {
		spin_lock_init(&fc->lock);
		mutex_init(&fc->inst_mutex);
		atomic_set(&fc->count, 1);
		init_waitqueue_head(&fc->waitq);
		init_waitqueue_head(&fc->blocked_waitq);
		init_waitqueue_head(&fc->reserved_req_waitq);
		INIT_LIST_HEAD(&fc->pending);
		INIT_LIST_HEAD(&fc->processing);
		INIT_LIST_HEAD(&fc->io);
		INIT_LIST_HEAD(&fc->interrupts);
		atomic_set(&fc->num_waiting, 0);
		fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
		fc->bdi.unplug_io_fn = default_unplug_io_fn;
		err = bdi_init(&fc->bdi);
		if (err) {
			kfree(fc);
			fc = NULL;
			goto out;
		}
		fc->reqctr = 0;
		fc->blocked = 1;
		fc->attr_version = 1;
		get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
	}
out:
	return fc;
}

void fuse_conn_put(struct fuse_conn *fc)
{
	if (atomic_dec_and_test(&fc->count)) {
		if (fc->destroy_req)
			fuse_request_free(fc->destroy_req);
		mutex_destroy(&fc->inst_mutex);
		bdi_destroy(&fc->bdi);
		kfree(fc);
	}
}

struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
{
	atomic_inc(&fc->count);
	return fc;
}

static struct inode *get_root_inode(struct super_block *sb, unsigned mode)
{
	struct fuse_attr attr;
	memset(&attr, 0, sizeof(attr));

	attr.mode = mode;
	attr.ino = FUSE_ROOT_ID;
	attr.nlink = 1;
	return fuse_iget(sb, 1, 0, &attr, 0, 0);
}

static const struct super_operations fuse_super_operations = {
	.alloc_inode    = fuse_alloc_inode,
	.destroy_inode  = fuse_destroy_inode,
	.read_inode	= fuse_read_inode,
	.clear_inode	= fuse_clear_inode,
	.drop_inode	= generic_delete_inode,
	.remount_fs	= fuse_remount_fs,
	.put_super	= fuse_put_super,
	.umount_begin	= fuse_umount_begin,
	.statfs		= fuse_statfs,
	.show_options	= fuse_show_options,
};

static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
{
	struct fuse_init_out *arg = &req->misc.init_out;

	if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
		fc->conn_error = 1;
	else {
		unsigned long ra_pages;

		if (arg->minor >= 6) {
			ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
			if (arg->flags & FUSE_ASYNC_READ)
				fc->async_read = 1;
			if (!(arg->flags & FUSE_POSIX_LOCKS))
				fc->no_lock = 1;
			if (arg->flags & FUSE_ATOMIC_O_TRUNC)
				fc->atomic_o_trunc = 1;
		} else {
			ra_pages = fc->max_read / PAGE_CACHE_SIZE;
			fc->no_lock = 1;
		}

		fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
		fc->minor = arg->minor;
		fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
		fc->conn_init = 1;
	}
	fuse_put_request(fc, req);
	fc->blocked = 0;
	wake_up_all(&fc->blocked_waitq);
}

static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
{
	struct fuse_init_in *arg = &req->misc.init_in;

	arg->major = FUSE_KERNEL_VERSION;
	arg->minor = FUSE_KERNEL_MINOR_VERSION;
	arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
	arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC;
	req->in.h.opcode = FUSE_INIT;
	req->in.numargs = 1;
	req->in.args[0].size = sizeof(*arg);
	req->in.args[0].value = arg;
	req->out.numargs = 1;
	/* Variable length arguement used for backward compatibility
	   with interface version < 7.5.  Rest of init_out is zeroed
	   by do_get_request(), so a short reply is not a problem */
	req->out.argvar = 1;
	req->out.args[0].size = sizeof(struct fuse_init_out);
	req->out.args[0].value = &req->misc.init_out;
	req->end = process_init_reply;
	request_send_background(fc, req);
}

static u64 conn_id(void)
{
	static u64 ctr = 1;
	return ctr++;
}

static int fuse_fill_super(struct super_block *sb, void *data, int silent)
{
	struct fuse_conn *fc;
	struct inode *root;
	struct fuse_mount_data d;
	struct file *file;
	struct dentry *root_dentry;
	struct fuse_req *init_req;
	int err;
	int is_bdev = sb->s_bdev != NULL;

	if (sb->s_flags & MS_MANDLOCK)
		return -EINVAL;

	if (!parse_fuse_opt((char *) data, &d, is_bdev))
		return -EINVAL;

	if (is_bdev) {
#ifdef CONFIG_BLOCK
		if (!sb_set_blocksize(sb, d.blksize))
			return -EINVAL;
#endif
	} else {
		sb->s_blocksize = PAGE_CACHE_SIZE;
		sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	}
	sb->s_magic = FUSE_SUPER_MAGIC;
	sb->s_op = &fuse_super_operations;
	sb->s_maxbytes = MAX_LFS_FILESIZE;

	file = fget(d.fd);
	if (!file)
		return -EINVAL;

	if (file->f_op != &fuse_dev_operations)
		return -EINVAL;

	fc = new_conn();
	if (!fc)
		return -ENOMEM;

	fc->flags = d.flags;
	fc->user_id = d.user_id;
	fc->group_id = d.group_id;
	fc->max_read = d.max_read;

	/* Used by get_root_inode() */
	sb->s_fs_info = fc;

	err = -ENOMEM;
	root = get_root_inode(sb, d.rootmode);
	if (!root)
		goto err;

	root_dentry = d_alloc_root(root);
	if (!root_dentry) {
		iput(root);
		goto err;
	}

	init_req = fuse_request_alloc();
	if (!init_req)
		goto err_put_root;

	if (is_bdev) {
		fc->destroy_req = fuse_request_alloc();
		if (!fc->destroy_req)
			goto err_put_root;
	}

	mutex_lock(&fuse_mutex);
	err = -EINVAL;
	if (file->private_data)
		goto err_unlock;

	fc->id = conn_id();
	err = fuse_ctl_add_conn(fc);
	if (err)
		goto err_unlock;

	list_add_tail(&fc->entry, &fuse_conn_list);
	sb->s_root = root_dentry;
	fc->connected = 1;
	file->private_data = fuse_conn_get(fc);
	mutex_unlock(&fuse_mutex);
	/*
	 * atomic_dec_and_test() in fput() provides the necessary
	 * memory barrier for file->private_data to be visible on all
	 * CPUs after this
	 */
	fput(file);

	fuse_send_init(fc, init_req);

	return 0;

 err_unlock:
	mutex_unlock(&fuse_mutex);
	fuse_request_free(init_req);
 err_put_root:
	dput(root_dentry);
 err:
	fput(file);
	fuse_conn_put(fc);
	return err;
}

static int fuse_get_sb(struct file_system_type *fs_type,
		       int flags, const char *dev_name,
		       void *raw_data, struct vfsmount *mnt)
{
	return get_sb_nodev(fs_type, flags, raw_data, fuse_fill_super, mnt);
}

static struct file_system_type fuse_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "fuse",
	.fs_flags	= FS_HAS_SUBTYPE,
	.get_sb		= fuse_get_sb,
	.kill_sb	= kill_anon_super,
};

#ifdef CONFIG_BLOCK
static int fuse_get_sb_blk(struct file_system_type *fs_type,
			   int flags, const char *dev_name,
			   void *raw_data, struct vfsmount *mnt)
{
	return get_sb_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super,
			   mnt);
}

static struct file_system_type fuseblk_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "fuseblk",
	.get_sb		= fuse_get_sb_blk,
	.kill_sb	= kill_block_super,
	.fs_flags	= FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
};

static inline int register_fuseblk(void)
{
	return register_filesystem(&fuseblk_fs_type);
}

static inline void unregister_fuseblk(void)
{
	unregister_filesystem(&fuseblk_fs_type);
}
#else
static inline int register_fuseblk(void)
{
	return 0;
}

static inline void unregister_fuseblk(void)
{
}
#endif

static decl_subsys(fuse, NULL, NULL);
static decl_subsys(connections, NULL, NULL);

static void fuse_inode_init_once(struct kmem_cache *cachep, void *foo)
{
	struct inode * inode = foo;

	inode_init_once(inode);
}

static int __init fuse_fs_init(void)
{
	int err;

	err = register_filesystem(&fuse_fs_type);
	if (err)
		goto out;

	err = register_fuseblk();
	if (err)
		goto out_unreg;

	fuse_inode_cachep = kmem_cache_create("fuse_inode",
					      sizeof(struct fuse_inode),
					      0, SLAB_HWCACHE_ALIGN,
					      fuse_inode_init_once);
	err = -ENOMEM;
	if (!fuse_inode_cachep)
		goto out_unreg2;

	return 0;

 out_unreg2:
	unregister_fuseblk();
 out_unreg:
	unregister_filesystem(&fuse_fs_type);
 out:
	return err;
}

static void fuse_fs_cleanup(void)
{
	unregister_filesystem(&fuse_fs_type);
	unregister_fuseblk();
	kmem_cache_destroy(fuse_inode_cachep);
}

static int fuse_sysfs_init(void)
{
	int err;

	kobj_set_kset_s(&fuse_subsys, fs_subsys);
	err = subsystem_register(&fuse_subsys);
	if (err)
		goto out_err;

	kobj_set_kset_s(&connections_subsys, fuse_subsys);
	err = subsystem_register(&connections_subsys);
	if (err)
		goto out_fuse_unregister;

	return 0;

 out_fuse_unregister:
	subsystem_unregister(&fuse_subsys);
 out_err:
	return err;
}

static void fuse_sysfs_cleanup(void)
{
	subsystem_unregister(&connections_subsys);
	subsystem_unregister(&fuse_subsys);
}

static int __init fuse_init(void)
{
	int res;

	printk("fuse init (API version %i.%i)\n",
	       FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);

	INIT_LIST_HEAD(&fuse_conn_list);
	res = fuse_fs_init();
	if (res)
		goto err;

	res = fuse_dev_init();
	if (res)
		goto err_fs_cleanup;

	res = fuse_sysfs_init();
	if (res)
		goto err_dev_cleanup;

	res = fuse_ctl_init();
	if (res)
		goto err_sysfs_cleanup;

	return 0;

 err_sysfs_cleanup:
	fuse_sysfs_cleanup();
 err_dev_cleanup:
	fuse_dev_cleanup();
 err_fs_cleanup:
	fuse_fs_cleanup();
 err:
	return res;
}

static void __exit fuse_exit(void)
{
	printk(KERN_DEBUG "fuse exit\n");

	fuse_ctl_cleanup();
	fuse_sysfs_cleanup();
	fuse_fs_cleanup();
	fuse_dev_cleanup();
}

module_init(fuse_init);
module_exit(fuse_exit);