【linux内核】 fuse go 源码分析

结构体 Inode 

    StaleAttr 包括权限，编号，主要结构在 rawBridge

    注意：生成 Inode 使用 NewInode 或者 NewPersistentInode

// Inode is a node in VFS tree.  Inodes are one-to-one mapped to
// Operations instances, which is the extension interface for file
// systems.  One can create fully-formed trees of Inodes ahead of time
// by creating "persistent" Inodes.
//
// The Inode struct contains a lock, so it should not be
// copied. Inodes should be obtained by calling Inode.NewInode() or
// Inode.NewPersistentInode().
type Inode struct {
   stableAttr StableAttr

   ops    InodeEmbedder
   bridge *rawBridge

   // Following data is mutable.

   // file handles.
   // protected by bridge.mu
   openFiles []uint32

1. Mount 函数

    Mount 函数在目录 dir 下，挂载指定文件系统 NodeFS，开启服务请求

    如果未指定选项参数，则设置默认参数

// Mount mounts the given NodeFS on the directory, and starts serving
// requests. This is a convenience wrapper around NewNodeFS and
// fuse.NewServer.  If nil is given as options, default settings are
// applied, which are 1 second entry and attribute timeout.
func Mount(dir string, root InodeEmbedder, options *Options) (*fuse.Server, error) {
	if options == nil {
		oneSec := time.Second
		options = &Options{
			EntryTimeout: &oneSec,
			AttrTimeout:  &oneSec,
		}
	}

    1.1 NewNodeFS 函数

      使用了 bridge 变量定义 raw 文件系统，会不会学网络 bridge 概念，实例化，并设置参数

      如果 root 实现了 NodeOnAdder 接口，则调用 OnAdd 方法

// NewNodeFS creates a node based filesystem based on the
// InodeEmbedder instance for the root of the tree.
func NewNodeFS(root InodeEmbedder, opts *Options) fuse.RawFileSystem {
	
	initInode(root.embed(), root,
		StableAttr{
			Ino:  1,
			Mode: fuse.S_IFDIR,
		},
		bridge,
		false,
	)
	bridge.root = root.embed()
	bridge.root.lookupCount = 1
	bridge.nodes = map[uint64]*Inode{
		1: bridge.root,
	}

	// Fh 0 means no file handle.
	bridge.files = []*fileEntry{{}}

	if opts.OnAdd != nil {
		opts.OnAdd(context.Background())
	} else if oa, ok := root.(NodeOnAdder); ok {
		oa.OnAdd(context.Background())
	}

	return bridge
}

    1.2 NewServer 函数

      实例化 rawBridge 对象，实现了 RawFileSystem 接口，包括处理文件属性，读写等等ri

type RawFileSystem interface {
	// File handling.
	Create(cancel <-chan struct{}, input *CreateIn, name string, out *CreateOut) (code Status)
	Open(cancel <-chan struct{}, input *OpenIn, out *OpenOut) (status Status)
	Read(cancel <-chan struct{}, input *ReadIn, buf []byte) (ReadResult, Status)
	Lseek(cancel <-chan struct{}, in *LseekIn, out *LseekOut) Status
	// Directory handling
	OpenDir(cancel <-chan struct{}, input *OpenIn, out *OpenOut) (status Status)
	ReadDir(cancel <-chan struct{}, input *ReadIn, out *DirEntryList) Status
	ReadDirPlus(cancel <-chan struct{}, input *ReadIn, out *DirEntryList) Status
	ReleaseDir(input *ReleaseIn)
	FsyncDir(cancel <-chan struct{}, input *FsyncIn) (code Status)

     调用 mount 函数，其实是调用 fusermount 命令将文件系统挂载在设置的目录