Move the metaMu lock from the fs to the object

Signed-off-by: Anagh Kumar Baranwal <6824881+darthShadow@users.noreply.github.com>

backend/local/local.go

@@ -28,13 +28,13 @@ import (
 	"github.com/rclone/rclone/lib/encoder"
 	"github.com/rclone/rclone/lib/file"
 	"github.com/rclone/rclone/lib/readers"
+	"golang.org/x/sync/errgroup"
 	"golang.org/x/text/unicode/norm"
 )
 
 // Constants
-const devUnset = 0xdeadbeefcafebabe                                       // a device id meaning it is unset
-const linkSuffix = ".rclonelink"                                          // The suffix added to a translated symbolic link
-const useReadDir = (runtime.GOOS == "windows" || runtime.GOOS == "plan9") // these OSes read FileInfos directly
+const devUnset = 0xdeadbeefcafebabe // a device id meaning it is unset
+const linkSuffix = ".rclonelink"    // The suffix added to a translated symbolic link
 
 // Register with Fs
 func init() {
@@ -200,9 +200,9 @@ cause disk fragmentation and can be slow to work with.`,
 			Help: `Disable setting modtime.
 
 Normally rclone updates modification time of files after they are done
-uploading. This can cause permissions issues on Linux platforms when 
+uploading. This can cause permissions issues on Linux platforms when
 the user rclone is running as does not own the file uploaded, such as
-when copying to a CIFS mount owned by another user. If this option is 
+when copying to a CIFS mount owned by another user. If this option is
 enabled, rclone will no longer update the modtime after copying a file.`,
 			Default:  false,
 			Advanced: true,
@@ -247,16 +247,16 @@ type Fs struct {
 	xattrSupported atomic.Int32        // whether xattrs are supported
 
 	// do os.Lstat or os.Stat
-	lstat        func(name string) (os.FileInfo, error)
-	objectMetaMu sync.RWMutex // global lock for Object metadata
+	lstat func(name string) (os.FileInfo, error)
 }
 
 // Object represents a local filesystem object
 type Object struct {
-	fs     *Fs    // The Fs this object is part of
-	remote string // The remote path (encoded path)
-	path   string // The local path (OS path)
-	// When using these items the fs.objectMetaMu must be held
+	fs     *Fs          // The Fs this object is part of
+	remote string       // The remote path (encoded path)
+	path   string       // The local path (OS path)
+	metaMu sync.RWMutex // lock for metadata
+	// When using these items the metaMu must be held
 	size    int64 // file metadata - always present
 	mode    os.FileMode
 	modTime time.Time
@@ -485,102 +485,131 @@ func (f *Fs) List(ctx context.Context, dir string) (entries fs.DirEntries, err e
 	}()
 
 	for {
-		var fis []os.FileInfo
-		if useReadDir {
-			// Windows and Plan9 read the directory entries with the stat information in which
-			// shouldn't fail because of unreadable entries.
-			fis, err = fd.Readdir(1024)
-			if err == io.EOF && len(fis) == 0 {
-				break
-			}
-		} else {
-			// For other OSes we read the names only (which shouldn't fail) then stat the
-			// individual ourselves so we can log errors but not fail the directory read.
-			var names []string
-			names, err = fd.Readdirnames(1024)
-			if err == io.EOF && len(names) == 0 {
-				break
-			}
-			if err == nil {
-				for _, name := range names {
-					namepath := filepath.Join(fsDirPath, name)
-					fi, fierr := os.Lstat(namepath)
-					if os.IsNotExist(fierr) {
-						// skip entry removed by a concurrent goroutine
-						continue
-					}
-					if fierr != nil {
-						// Don't report errors on any file names that are excluded
-						if useFilter {
-							newRemote := f.cleanRemote(dir, name)
-							if !filter.IncludeRemote(newRemote) {
-								continue
-							}
-						}
-						fierr = fmt.Errorf("failed to get info about directory entry %q: %w", namepath, fierr)
-						fs.Errorf(dir, "%v", fierr)
-						_ = accounting.Stats(ctx).Error(fserrors.NoRetryError(fierr)) // fail the sync
-						continue
-					}
-					fis = append(fis, fi)
-				}
-			}
+		var des []os.DirEntry
+
+		des, err = fd.ReadDir(1024)
+		if err == io.EOF && len(des) == 0 {
+			break
 		}
 		if err != nil {
 			return nil, fmt.Errorf("failed to read directory entry: %w", err)
 		}
 
-		for _, fi := range fis {
-			name := fi.Name()
-			mode := fi.Mode()
-			newRemote := f.cleanRemote(dir, name)
-			// Follow symlinks if required
-			if f.opt.FollowSymlinks && (mode&os.ModeSymlink) != 0 {
-				localPath := filepath.Join(fsDirPath, name)
-				fi, err = os.Stat(localPath)
-				// Quietly skip errors on excluded files and directories
-				if err != nil && useFilter && !filter.IncludeRemote(newRemote) {
-					continue
+		loopEntries := make(fs.DirEntries, len(des))
+
+		g, gCtx := errgroup.WithContext(ctx)
+		g.SetLimit(fs.GetConfig(ctx).Checkers)
+		for i, de := range des {
+			i, de := i, de // https://golang.org/doc/faq#closures_and_goroutines
+			g.Go(func() error {
+				// No point in continuing if context has been cancelled
+				if gCtx.Err() != nil {
+					return nil
 				}
-				if os.IsNotExist(err) || isCircularSymlinkError(err) {
-					// Skip bad symlinks and circular symlinks
-					err = fserrors.NoRetryError(fmt.Errorf("symlink: %w", err))
-					fs.Errorf(newRemote, "Listing error: %v", err)
-					err = accounting.Stats(ctx).Error(err)
-					continue
+
+				var (
+					err error
+					fi  os.FileInfo
+				)
+				name := de.Name()
+				mode := de.Type()
+				namepath := filepath.Join(fsDirPath, name)
+				newRemote := f.cleanRemote(dir, name)
+
+				if de.IsDir() {
+					// Ignore directories which are symlinks. These are junction points under windows which
+					// are kind of a souped up symlink. Unix doesn't have directories which are symlinks.
+					if (mode & os.ModeSymlink) != 0 {
+						return nil
+					}
 				}
+
+				fi, err = de.Info()
 				if err != nil {
-					return nil, err
+					if os.IsNotExist(err) {
+						// skip entry removed by a concurrent goroutine
+						return nil
+					}
+					if useFilter && !filter.IncludeRemote(newRemote) {
+						return nil
+					}
+					err = fmt.Errorf("failed to get info about directory entry %q: %w", namepath, err)
+					fs.Errorf(dir, "%v", err)
+					_ = accounting.Stats(gCtx).Error(fserrors.NoRetryError(err)) // fail the sync
+					return nil
 				}
+
+				name = fi.Name()
 				mode = fi.Mode()
+				namepath = filepath.Join(fsDirPath, name)
+				newRemote = f.cleanRemote(dir, name)
+
+				// Follow symlinks if required
+				if f.opt.FollowSymlinks && (mode&os.ModeSymlink) != 0 {
+					fi, err = os.Stat(namepath)
+					if err != nil {
+						// Quietly skip errors on excluded files and directories
+						if useFilter && !filter.IncludeRemote(newRemote) {
+							return nil
+						}
+						if os.IsNotExist(err) || isCircularSymlinkError(err) {
+							// Skip bad symlinks and circular symlinks
+							err = fserrors.NoRetryError(fmt.Errorf("symlink: %w", err))
+							fs.Errorf(newRemote, "Listing error: %v", err)
+							_ = accounting.Stats(gCtx).Error(err)
+							return nil
+						}
+						return err
+					}
+					mode = fi.Mode()
+				}
+
+				// No point in continuing if context has been cancelled
+				if gCtx.Err() != nil {
+					return nil
+				}
+
+				if fi.IsDir() {
+					if f.dev == readDevice(fi, f.opt.OneFileSystem) {
+						d := fs.NewDir(newRemote, fi.ModTime())
+						loopEntries[i] = d
+						return nil
+					}
+				} else {
+					// Check whether this link should be translated
+					if f.opt.TranslateSymlinks && mode&os.ModeSymlink != 0 {
+						newRemote += linkSuffix
+					}
+					// Don't include non directory if not included
+					// we leave directory filtering to the layer above
+					if useFilter && !filter.IncludeRemote(newRemote) {
+						return nil
+					}
+					fso, err := f.newObjectWithInfo(newRemote, fi)
+					if err != nil {
+						return err
+					}
+					if fso.Storable() {
+						loopEntries[i] = fso
+						return nil
+					}
+				}
+				return nil
+			})
+		}
+		err = g.Wait()
+		if err != nil {
+			return nil, err
+		}
+
+		for _, entry := range loopEntries {
+			if entry == nil {
+				continue
 			}
-			if fi.IsDir() {
-				// Ignore directories which are symlinks.  These are junction points under windows which
-				// are kind of a souped up symlink. Unix doesn't have directories which are symlinks.
-				if (mode&os.ModeSymlink) == 0 && f.dev == readDevice(fi, f.opt.OneFileSystem) {
-					d := fs.NewDir(newRemote, fi.ModTime())
-					entries = append(entries, d)
-				}
-			} else {
-				// Check whether this link should be translated
-				if f.opt.TranslateSymlinks && fi.Mode()&os.ModeSymlink != 0 {
-					newRemote += linkSuffix
-				}
-				// Don't include non directory if not included
-				// we leave directory filtering to the layer above
-				if useFilter && !filter.IncludeRemote(newRemote) {
-					continue
-				}
-				fso, err := f.newObjectWithInfo(newRemote, fi)
-				if err != nil {
-					return nil, err
-				}
-				if fso.Storable() {
-					entries = append(entries, fso)
-				}
-			}
+			entries = append(entries, entry)
 		}
 	}
+
 	return entries, nil
 }
 
@@ -748,9 +777,9 @@ func (f *Fs) Move(ctx context.Context, src fs.Object, remote string) (fs.Object,
 
 	// Temporary Object under construction
 	dstObj := f.newObject(remote)
-	dstObj.fs.objectMetaMu.RLock()
+	dstObj.metaMu.RLock()
 	dstObjMode := dstObj.mode
-	dstObj.fs.objectMetaMu.RUnlock()
+	dstObj.metaMu.RUnlock()
 
 	// Check it is a file if it exists
 	err := dstObj.lstat()
@@ -912,10 +941,10 @@ func (o *Object) Remote() string {
 // Hash returns the requested hash of a file as a lowercase hex string
 func (o *Object) Hash(ctx context.Context, r hash.Type) (string, error) {
 	// Check that the underlying file hasn't changed
-	o.fs.objectMetaMu.RLock()
+	o.metaMu.RLock()
 	oldtime := o.modTime
 	oldsize := o.size
-	o.fs.objectMetaMu.RUnlock()
+	o.metaMu.RUnlock()
 	err := o.lstat()
 	var changed bool
 	if err != nil {
@@ -927,14 +956,14 @@ func (o *Object) Hash(ctx context.Context, r hash.Type) (string, error) {
 			return "", fmt.Errorf("hash: failed to stat: %w", err)
 		}
 	} else {
-		o.fs.objectMetaMu.RLock()
+		o.metaMu.RLock()
 		changed = !o.modTime.Equal(oldtime) || oldsize != o.size
-		o.fs.objectMetaMu.RUnlock()
+		o.metaMu.RUnlock()
 	}
 
-	o.fs.objectMetaMu.RLock()
+	o.metaMu.RLock()
 	hashValue, hashFound := o.hashes[r]
-	o.fs.objectMetaMu.RUnlock()
+	o.metaMu.RUnlock()
 
 	if changed || !hashFound {
 		var in io.ReadCloser
@@ -965,28 +994,28 @@ func (o *Object) Hash(ctx context.Context, r hash.Type) (string, error) {
 			return "", fmt.Errorf("hash: failed to close: %w", closeErr)
 		}
 		hashValue = hashes[r]
-		o.fs.objectMetaMu.Lock()
+		o.metaMu.Lock()
 		if o.hashes == nil {
 			o.hashes = hashes
 		} else {
 			o.hashes[r] = hashValue
 		}
-		o.fs.objectMetaMu.Unlock()
+		o.metaMu.Unlock()
 	}
 	return hashValue, nil
 }
 
 // Size returns the size of an object in bytes
 func (o *Object) Size() int64 {
-	o.fs.objectMetaMu.RLock()
-	defer o.fs.objectMetaMu.RUnlock()
+	o.metaMu.RLock()
+	defer o.metaMu.RUnlock()
 	return o.size
 }
 
 // ModTime returns the modification time of the object
 func (o *Object) ModTime(ctx context.Context) time.Time {
-	o.fs.objectMetaMu.RLock()
-	defer o.fs.objectMetaMu.RUnlock()
+	o.metaMu.RLock()
+	defer o.metaMu.RUnlock()
 	return o.modTime
 }
 
@@ -1015,9 +1044,9 @@ func (o *Object) SetModTime(ctx context.Context, modTime time.Time) error {
 
 // Storable returns a boolean showing if this object is storable
 func (o *Object) Storable() bool {
-	o.fs.objectMetaMu.RLock()
+	o.metaMu.RLock()
 	mode := o.mode
-	o.fs.objectMetaMu.RUnlock()
+	o.metaMu.RUnlock()
 	if mode&os.ModeSymlink != 0 && !o.fs.opt.TranslateSymlinks {
 		if !o.fs.opt.SkipSymlinks {
 			fs.Logf(o, "Can't follow symlink without -L/--copy-links")
@@ -1050,10 +1079,10 @@ func (file *localOpenFile) Read(p []byte) (n int, err error) {
 		if err != nil {
 			return 0, fmt.Errorf("can't read status of source file while transferring: %w", err)
 		}
-		file.o.fs.objectMetaMu.RLock()
+		file.o.metaMu.RLock()
 		oldtime := file.o.modTime
 		oldsize := file.o.size
-		file.o.fs.objectMetaMu.RUnlock()
+		file.o.metaMu.RUnlock()
 		if oldsize != fi.Size() {
 			return 0, fserrors.NoLowLevelRetryError(fmt.Errorf("can't copy - source file is being updated (size changed from %d to %d)", oldsize, fi.Size()))
 		}
@@ -1075,9 +1104,9 @@ func (file *localOpenFile) Close() (err error) {
 	err = file.in.Close()
 	if err == nil {
 		if file.hash.Size() == file.o.Size() {
-			file.o.fs.objectMetaMu.Lock()
+			file.o.metaMu.Lock()
 			file.o.hashes = file.hash.Sums()
-			file.o.fs.objectMetaMu.Unlock()
+			file.o.metaMu.Unlock()
 		}
 	}
 	return err
@@ -1269,9 +1298,9 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 
 	// All successful so update the hashes
 	if hasher != nil {
-		o.fs.objectMetaMu.Lock()
+		o.metaMu.Lock()
 		o.hashes = hasher.Sums()
-		o.fs.objectMetaMu.Unlock()
+		o.metaMu.Unlock()
 	}
 
 	// Set the mtime
@@ -1345,11 +1374,11 @@ func (o *Object) setMetadata(info os.FileInfo) {
 	if o.fs.opt.NoCheckUpdated && !o.modTime.IsZero() {
 		return
 	}
-	o.fs.objectMetaMu.Lock()
+	o.metaMu.Lock()
 	o.size = info.Size()
 	o.modTime = info.ModTime()
 	o.mode = info.Mode()
-	o.fs.objectMetaMu.Unlock()
+	o.metaMu.Unlock()
 	// Read the size of the link.
 	//
 	// The value in info.Size() is not always correct
@@ -1368,9 +1397,9 @@ func (o *Object) setMetadata(info os.FileInfo) {
 
 // clearHashCache wipes any cached hashes for the object
 func (o *Object) clearHashCache() {
-	o.fs.objectMetaMu.Lock()
+	o.metaMu.Lock()
 	o.hashes = nil
-	o.fs.objectMetaMu.Unlock()
+	o.metaMu.Unlock()
 }
 
 // Stat an Object into info