nodefs: more comments

nodefs/README.md

@@ -12,6 +12,10 @@ Decisions
      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.
@@ -52,9 +56,6 @@ To decide
 
    * Should we provide automatic fileID numbering?
    
-   * One giant interface with many methods, or many one-method
-     interfaces? Or some interface (file, dir, symlink, etc).
- 
    * function signatures, or types? The latter is easier to remember?
      Easier to extend? The latter less efficient (indirections/copies)
 
@@ -83,6 +84,4 @@ or
    * Should bridge.Lookup() add the child, bridge.Unlink remove the child, etc.?
 
    * Merge Fsync/FsyncDir?
-
-   * Merge Release/ReleaseDir? (others?)
  

nodefs/api.go

@@ -83,15 +83,6 @@ type DirStream interface {
 	Close()
 }
 
-/*
-NOSUBMIT: how to structure?
-
-- one interface per method?
-- one interface for files (getattr, read/write), one for dirs (lookup, opendir), one shared?
-- one giant interface?
-- use raw types as args rather than mimicking Golang signatures?
-*/
-
 // Operations is the interface that implements the filesystem.  Each
 // Operations instance must embed DefaultNode.
 type Operations interface {
@@ -112,7 +103,7 @@ type Operations interface {
 	// Access should return if the caller can access the file with
 	// the given mode. In this case, the context has data about
 	// the real UID. For example a root-SUID binary called by user
-	// `susan` gets the UID and GID for `susan` here.
+	// susan gets the UID and GID for susan here.
 	Access(ctx context.Context, mask uint32) fuse.Status
 
 	// Extended attributes
@@ -122,8 +113,8 @@ type Operations interface {
 	// small, it should return ERANGE and the size of the attribute.
 	GetXAttr(ctx context.Context, attr string, dest []byte) (uint32, fuse.Status)
 
-	// SetXAttr should store data for the given attribute.
-	// XXX flags.
+	// SetXAttr should store data for the given attribute.  See
+	// setxattr(2) for information about flags.
 	SetXAttr(ctx context.Context, attr string, data []byte, flags uint32) fuse.Status
 
 	// RemoveXAttr should delete the given attribute.
@@ -134,8 +125,10 @@ type Operations interface {
 	// ERANGE and the correct size.
 	ListXAttr(ctx context.Context, dest []byte) (uint32, fuse.Status)
 
+	// GetAttr reads attributes for an Inode
 	GetAttr(ctx context.Context, out *fuse.AttrOut) fuse.Status
 
+	// SetAttr sets attributes for an Inode
 	SetAttr(ctx context.Context, in *fuse.SetAttrIn, out *fuse.AttrOut) fuse.Status
 }
 

nodefs/default.go

@@ -14,7 +14,7 @@ import (
 	"github.com/hanwen/go-fuse/fuse"
 )
 
-// DefaultOperations provides common base Node functionality.
+// DefaultOperations provides stubs that return ENOSYS for all functions
 //
 // It must be embedded in any Node implementation.
 type DefaultOperations struct {