inode.c

FUSE文件系统开发工具,将内核层面的文件系统开发过程平移到应用层面上来。

	int type = 1;
	u64 nodeid;
	u32 generation;

	if (len < 3 || (connectable && len < 6))
		return  255;

	nodeid = get_fuse_inode(inode)->nodeid;
	generation = inode->i_generation;

	len = 3;
	fh[0] = (u32)(nodeid >> 32);
	fh[1] = (u32)(nodeid & 0xffffffff);
	fh[2] = generation;

	if (connectable && !S_ISDIR(inode->i_mode)) {
		struct inode *parent;

		spin_lock(&dentry->d_lock);
		parent = dentry->d_parent->d_inode;
		nodeid = get_fuse_inode(parent)->nodeid;
		generation = parent->i_generation;

		fh[3] = (u32)(nodeid >> 32);
		fh[4] = (u32)(nodeid & 0xffffffff);
		fh[5] = generation;
		spin_unlock(&dentry->d_lock);

		len = 6;
		type = 2;
	}

	*max_len = len;
	return type;
}

#ifdef KERNEL_2_6_24_PLUS
static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
		struct fid *fid, int fh_len, int fh_type)
{
	struct fuse_inode_handle handle;

	if (fh_len < 3 || fh_type > 2)
		return NULL;

	handle.nodeid = (u64) fid->raw[0] << 32;
	handle.nodeid |= (u64) fid->raw[1];
	handle.generation = fid->raw[2];
	return fuse_get_dentry(sb, &handle);
}

static struct dentry *fuse_fh_to_parent(struct super_block *sb,
		struct fid *fid, int fh_len, int fh_type)
{
	struct fuse_inode_handle parent;

	if (fh_type != 2 || fh_len < 6)
		return NULL;

	parent.nodeid = (u64) fid->raw[3] << 32;
	parent.nodeid |= (u64) fid->raw[4];
	parent.generation = fid->raw[5];
	return fuse_get_dentry(sb, &parent);
}


static const struct export_operations fuse_export_operations = {
	.fh_to_dentry	= fuse_fh_to_dentry,
	.fh_to_parent	= fuse_fh_to_parent,
	.encode_fh	= fuse_encode_fh,
};
#else
static struct dentry *fuse_get_dentry_old(struct super_block *sb, void *objp)
{
	return fuse_get_dentry(sb, objp);
}

static struct export_operations fuse_export_operations;

static struct dentry *fuse_decode_fh(struct super_block *sb, u32 *fh,
			int fh_len, int fileid_type,
			int (*acceptable)(void *context, struct dentry *de),
			void *context)
{
	struct fuse_inode_handle handle;
	struct fuse_inode_handle parent;

	if (fh_len < 3 || fileid_type > 2)
		return NULL;

	if (fileid_type == 2) {
		if (fh_len < 6)
			return NULL;

		parent.nodeid = (u64) fh[3] << 32;
		parent.nodeid |= (u64) fh[4];
		parent.generation = fh[5];
	} else {
		parent.nodeid = 0;
		parent.generation = 0;
	}

	handle.nodeid = (u64) fh[0] << 32;
	handle.nodeid |= (u64) fh[1];
	handle.generation = fh[2];

	return fuse_export_operations.
		find_exported_dentry(sb, &handle, &parent, acceptable, context);
}

static struct export_operations fuse_export_operations = {
	.get_dentry	= fuse_get_dentry_old,
	.encode_fh      = fuse_encode_fh,
	.decode_fh	= fuse_decode_fh,
};
#endif
#endif

static struct super_operations fuse_super_operations = {
	.alloc_inode    = fuse_alloc_inode,
	.destroy_inode  = fuse_destroy_inode,
#ifndef KERNEL_2_6_25_PLUS
	.read_inode	= fuse_read_inode,
#endif
	.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;
		} 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;
	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;

	/* This is a privileged option */
	if ((d.flags & FUSE_ALLOW_OTHER) && !capable(CAP_SYS_ADMIN))
		return -EPERM;

	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;
#ifndef FUSE_MAINLINE
	sb->s_export_op = &fuse_export_operations;
#endif

	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;
}

#ifdef KERNEL_2_6_18_PLUS
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);
}
#else
static struct super_block *fuse_get_sb(struct file_system_type *fs_type,
				       int flags, const char *dev_name,
				       void *raw_data)
{
	return get_sb_nodev(fs_type, flags, raw_data, fuse_fill_super);
}
#endif

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

#ifdef CONFIG_BLOCK
#ifdef KERNEL_2_6_18_PLUS
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);
}
#else
static struct super_block *fuse_get_sb_blk(struct file_system_type *fs_type,
					   int flags, const char *dev_name,
					   void *raw_data)
{
	return get_sb_bdev(fs_type, flags, dev_name, raw_data,
			   fuse_fill_super);
}
#endif

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

#ifdef KERNEL_2_6_25_PLUS
static struct kobject *fuse_kobj;
static struct kobject *connections_kobj;
#else
#ifndef HAVE_FS_SUBSYS
static decl_subsys(fs, NULL, NULL);
#endif
static decl_subsys(fuse, NULL, NULL);
static decl_subsys(connections, NULL, NULL);
#endif

#ifdef KERNEL_2_6_24_PLUS
static void fuse_inode_init_once(struct kmem_cache *cachep, void *foo)
#else
static void fuse_inode_init_once(void *foo, struct kmem_cache *cachep,
				 unsigned long flags)
#endif
{
	struct inode * inode = foo;

#ifndef KERNEL_2_6_22_PLUS
	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
	    SLAB_CTOR_CONSTRUCTOR)
#endif
	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;

#ifdef KERNEL_2_6_23_PLUS
	fuse_inode_cachep = kmem_cache_create("fuse_inode",
					      sizeof(struct fuse_inode),
					      0, SLAB_HWCACHE_ALIGN,
					      fuse_inode_init_once);
#else
	fuse_inode_cachep = kmem_cache_create("fuse_inode",
					      sizeof(struct fuse_inode),
					      0, SLAB_HWCACHE_ALIGN,
					      fuse_inode_init_once, NULL);
#endif

	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;

#ifdef KERNEL_2_6_25_PLUS
	fuse_kobj = kobject_create_and_add("fuse", fs_kobj);
	if (!fuse_kobj) {
		err = -ENOMEM;
		goto out_err;
	}

	connections_kobj = kobject_create_and_add("connections", fuse_kobj);
	if (!connections_kobj) {
		err = -ENOMEM;
		goto out_fuse_unregister;
	}

	return 0;

 out_fuse_unregister:
	kobject_put(fuse_kobj);
 out_err:
#else
#ifndef HAVE_FS_SUBSYS
	err = subsystem_register(&fs_subsys);
	if (err)
		return err;
#endif
#ifdef KERNEL_2_6_22_PLUS
	kobj_set_kset_s(&fuse_subsys, fs_subsys);
#else
	kset_set_kset_s(&fuse_subsys, fs_subsys);
#endif
	err = subsystem_register(&fuse_subsys);
	if (err)
		goto out_err;

#ifdef KERNEL_2_6_22_PLUS
	kobj_set_kset_s(&connections_subsys, fuse_subsys);
#else
	kset_set_kset_s(&connections_subsys, fuse_subsys);
#endif
	err = subsystem_register(&connections_subsys);
	if (err)
		goto out_fuse_unregister;

	return 0;

 out_fuse_unregister:
	subsystem_unregister(&fuse_subsys);
 out_err:
#ifndef HAVE_FS_SUBSYS
	subsystem_unregister(&fs_subsys);
#endif
#endif
	return err;
}

static void fuse_sysfs_cleanup(void)
{
#ifdef KERNEL_2_6_25_PLUS
	kobject_put(connections_kobj);
	kobject_put(fuse_kobj);
#else
	subsystem_unregister(&connections_subsys);
	subsystem_unregister(&fuse_subsys);
#ifndef HAVE_FS_SUBSYS
	subsystem_unregister(&fs_subsys);
#endif
#endif
}

static int __init fuse_init(void)
{
	int res;

	printk("fuse init (API version %i.%i)\n",
	       FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
#ifndef FUSE_MAINLINE
	printk("fuse distribution version: %s\n", FUSE_VERSION);
#endif

	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);