From 17ac5244c31d06f7065bd8ed9a416d00e048b23c Mon Sep 17 00:00:00 2001
From: chrislu <chris.lu@gmail.com>
Date: Tue, 15 Feb 2022 01:44:17 -0800
Subject: [PATCH] mount2: avoid double listing directories

---
 weed/mount/weedfs.go          |  2 +
 weed/mount/weedfs_dir_read.go | 83 +++++++++++++++++++++++++++++++----
 2 files changed, 77 insertions(+), 8 deletions(-)

diff --git a/weed/mount/weedfs.go b/weed/mount/weedfs.go
index 072f562fc..25ef830ae 100644
--- a/weed/mount/weedfs.go
+++ b/weed/mount/weedfs.go
@@ -67,6 +67,7 @@ type WFS struct {
 	concurrentWriters *util.LimitedConcurrentExecutor
 	inodeToPath       *InodeToPath
 	fhmap             *FileHandleToInode
+	dhmap             *DirectoryHandleToInode
 }
 
 func NewSeaweedFileSystem(option *Option) *WFS {
@@ -76,6 +77,7 @@ func NewSeaweedFileSystem(option *Option) *WFS {
 		signature:     util.RandomInt32(),
 		inodeToPath:   NewInodeToPath(),
 		fhmap:         NewFileHandleToInode(),
+		dhmap:         NewDirectoryHandleToInode(),
 	}
 
 	wfs.root = Directory{
diff --git a/weed/mount/weedfs_dir_read.go b/weed/mount/weedfs_dir_read.go
index b14bacc1f..99882fcf8 100644
--- a/weed/mount/weedfs_dir_read.go
+++ b/weed/mount/weedfs_dir_read.go
@@ -9,8 +9,66 @@ import (
 	"github.com/hanwen/go-fuse/v2/fuse"
 	"math"
 	"os"
+	"sync"
 )
 
+type DirectoryHandleId uint64
+
+type DirectoryHandle struct {
+	isFinished    bool
+	counter       uint32
+	lastEntryName string
+}
+
+type DirectoryHandleToInode struct {
+	// shares the file handle id sequencer with FileHandleToInode{nextFh}
+	sync.Mutex
+	dir2inode map[DirectoryHandleId]*DirectoryHandle
+}
+
+func NewDirectoryHandleToInode() *DirectoryHandleToInode {
+	return &DirectoryHandleToInode{
+		dir2inode: make(map[DirectoryHandleId]*DirectoryHandle),
+	}
+}
+
+func (wfs *WFS) AcquireDirectoryHandle() (DirectoryHandleId, *DirectoryHandle) {
+	wfs.fhmap.Lock()
+	fh := wfs.fhmap.nextFh
+	wfs.fhmap.nextFh++
+	wfs.fhmap.Unlock()
+
+	wfs.dhmap.Lock()
+	defer wfs.dhmap.Unlock()
+	dh := &DirectoryHandle{
+		isFinished:    false,
+		lastEntryName: "",
+	}
+	wfs.dhmap.dir2inode[DirectoryHandleId(fh)] = dh
+	return DirectoryHandleId(fh), dh
+}
+
+func (wfs *WFS) GetDirectoryHandle(dhid DirectoryHandleId) *DirectoryHandle {
+	wfs.dhmap.Lock()
+	defer wfs.dhmap.Unlock()
+	if dh, found := wfs.dhmap.dir2inode[dhid]; found {
+		return dh
+	}
+	dh := &DirectoryHandle{
+		isFinished:    false,
+		lastEntryName: "",
+	}
+
+	wfs.dhmap.dir2inode[dhid] = dh
+	return dh
+}
+
+func (wfs *WFS) ReleaseDirectoryHandle(dhid DirectoryHandleId) {
+	wfs.dhmap.Lock()
+	defer wfs.dhmap.Unlock()
+	delete(wfs.dhmap.dir2inode, dhid)
+}
+
 // Directory handling
 
 /** Open directory
@@ -25,6 +83,8 @@ func (wfs *WFS) OpenDir(cancel <-chan struct{}, input *fuse.OpenIn, out *fuse.Op
 	if !wfs.inodeToPath.HasInode(input.NodeId) {
 		return fuse.ENOENT
 	}
+	dhid, _ := wfs.AcquireDirectoryHandle()
+	out.Fh = uint64(dhid)
 	return fuse.OK
 }
 
@@ -34,6 +94,7 @@ func (wfs *WFS) OpenDir(cancel <-chan struct{}, input *fuse.OpenIn, out *fuse.Op
  * path parameter will be NULL.
  */
 func (wfs *WFS) ReleaseDir(input *fuse.ReleaseIn) {
+	wfs.ReleaseDirectoryHandle(DirectoryHandleId(input.Fh))
 }
 
 /** Synchronize directory contents
@@ -72,18 +133,23 @@ func (wfs *WFS) ReadDirPlus(cancel <-chan struct{}, input *fuse.ReadIn, out *fus
 }
 
 func (wfs *WFS) doReadDirectory(input *fuse.ReadIn, out *fuse.DirEntryList, isPlusMode bool) fuse.Status {
+
+	dh := wfs.GetDirectoryHandle(DirectoryHandleId(input.Fh))
+	if dh.isFinished {
+		return fuse.OK
+	}
+
 	dirPath := wfs.inodeToPath.GetPath(input.NodeId)
 
-	var counter uint64
 	var dirEntry fuse.DirEntry
 	if input.Offset == 0 && !isPlusMode {
-		counter++
+		dh.counter++
 		dirEntry.Ino = input.NodeId
 		dirEntry.Name = "."
 		dirEntry.Mode = toSystemMode(os.ModeDir)
 		out.AddDirEntry(dirEntry)
 
-		counter++
+		dh.counter++
 		parentDir, _ := dirPath.DirAndName()
 		parentInode := wfs.inodeToPath.GetInode(util.FullPath(parentDir))
 		dirEntry.Ino = parentInode
@@ -94,10 +160,7 @@ func (wfs *WFS) doReadDirectory(input *fuse.ReadIn, out *fuse.DirEntryList, isPl
 	}
 
 	processEachEntryFn := func(entry *filer.Entry, isLast bool) bool {
-		counter++
-		if counter <= input.Offset {
-			return true
-		}
+		dh.counter++
 		dirEntry.Name = entry.Name()
 		inode := wfs.inodeToPath.GetInode(dirPath.Child(dirEntry.Name))
 		dirEntry.Ino = inode
@@ -113,6 +176,7 @@ func (wfs *WFS) doReadDirectory(input *fuse.ReadIn, out *fuse.DirEntryList, isPl
 			}
 			wfs.outputFilerEntry(entryOut, inode, entry)
 		}
+		dh.lastEntryName = entry.Name()
 		return true
 	}
 
@@ -120,13 +184,16 @@ func (wfs *WFS) doReadDirectory(input *fuse.ReadIn, out *fuse.DirEntryList, isPl
 		glog.Errorf("dir ReadDirAll %s: %v", dirPath, err)
 		return fuse.EIO
 	}
-	listErr := wfs.metaCache.ListDirectoryEntries(context.Background(), dirPath, "", false, int64(math.MaxInt32), func(entry *filer.Entry) bool {
+	listErr := wfs.metaCache.ListDirectoryEntries(context.Background(), dirPath, dh.lastEntryName, false, int64(math.MaxInt32), func(entry *filer.Entry) bool {
 		return processEachEntryFn(entry, false)
 	})
 	if listErr != nil {
 		glog.Errorf("list meta cache: %v", listErr)
 		return fuse.EIO
 	}
+	if dh.counter < input.Length {
+		dh.isFinished = true
+	}
 
 	return fuse.OK
 }