Initial commit

Proof-of-concept implementation. Bugs will occur.

vendor/github.com/hanwen/go-fuse/v2/fs/README.md

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+
+Objective
+=========
+
+A high-performance FUSE API that minimizes pitfalls with writing
+correct filesystems.
+
+Decisions
+=========
+
+   * Nodes contain references to their children. This is useful
+     because most filesystems will need to construct tree-like
+     structures.
+
+   * Nodes contain references to their parents. As a result, we can
+     derive the path for each Inode, and there is no need for a
+     separate PathFS.
+
+   * Nodes can be "persistent", meaning their lifetime is not under
+     control of the kernel. This is useful for constructing FS trees
+     in advance, rather than driven by LOOKUP.
+
+   * The NodeID (used for communicating with the kernel, not to be
+     confused with the inode number reported by `ls -i`) is generated
+     internally and immutable for an Inode.  This avoids any races
+     between LOOKUP, NOTIFY and FORGET.
+     
+   * The mode of an Inode is defined on creation.  Files cannot change
+     type during their lifetime. This also prevents the common error
+     of forgetting to return the filetype in Lookup/GetAttr.
+     
+   * No global treelock, to ensure scalability.
+
+   * Support for hard links. libfuse doesn't support this in the
+     high-level API.  Extra care for race conditions is needed when
+     looking up the same file through different paths.
+
+   * do not issue Notify{Entry,Delete} as part of
+     AddChild/RmChild/MvChild: because NodeIDs are unique and
+     immutable, there is no confusion about which nodes are
+     invalidated, and the notification doesn't have to happen under
+     lock.
+
+   * Directory reading uses the FileHandles as well, the API for read
+     is one DirEntry at a time. FileHandles may implement seeking, and we
+     call the Seek if we see Offsets change in the incoming request.
+   
+   * Method names are based on syscall names. Where there is no
+     syscall (eg. "open directory"), we bias towards writing
+     everything together (Opendir)