Merge pull request #4020 from greatroar/fuse-inode

fuse: Better inode generation

internal/fuse/dir.go

@@ -182,7 +182,7 @@ func (d *dir) ReadDirAll(ctx context.Context) ([]fuse.Dirent, error) {
 		}
 
 		ret = append(ret, fuse.Dirent{
-			Inode: fs.GenerateDynamicInode(d.inode, name),
+			Inode: inodeFromNode(d.inode, node),
 			Type:  typ,
 			Name:  name,
 		})
@@ -204,15 +204,16 @@ func (d *dir) Lookup(ctx context.Context, name string) (fs.Node, error) {
 		debug.Log("  Lookup(%v) -> not found", name)
 		return nil, fuse.ENOENT
 	}
+	inode := inodeFromNode(d.inode, node)
 	switch node.Type {
 	case "dir":
-		return newDir(d.root, fs.GenerateDynamicInode(d.inode, name), d.inode, node)
+		return newDir(d.root, inode, d.inode, node)
 	case "file":
-		return newFile(d.root, fs.GenerateDynamicInode(d.inode, name), node)
+		return newFile(d.root, inode, node)
 	case "symlink":
-		return newLink(d.root, fs.GenerateDynamicInode(d.inode, name), node)
+		return newLink(d.root, inode, node)
 	case "dev", "chardev", "fifo", "socket":
-		return newOther(d.root, fs.GenerateDynamicInode(d.inode, name), node)
+		return newOther(d.root, inode, node)
 	default:
 		debug.Log("  node %v has unknown type %v", name, node.Type)
 		return nil, fuse.ENOENT

internal/fuse/fuse_test.go

@@ -118,7 +118,7 @@ func TestFuseFile(t *testing.T) {
 	}
 	root := &Root{repo: repo, blobCache: bloblru.New(blobCacheSize)}
 
-	inode := fs.GenerateDynamicInode(1, "foo")
+	inode := inodeFromNode(1, node)
 	f, err := newFile(root, inode, node)
 	rtest.OK(t, err)
 	of, err := f.Open(context.TODO(), nil, nil)
@@ -161,8 +161,8 @@ func TestFuseDir(t *testing.T) {
 		ChangeTime: time.Unix(1606773732, 0),
 		ModTime:    time.Unix(1606773733, 0),
 	}
-	parentInode := fs.GenerateDynamicInode(0, "parent")
-	inode := fs.GenerateDynamicInode(1, "foo")
+	parentInode := inodeFromName(0, "parent")
+	inode := inodeFromName(1, "foo")
 	d, err := newDir(root, inode, parentInode, node)
 	rtest.OK(t, err)
 
@@ -219,3 +219,40 @@ func testTopUIDGID(t *testing.T, cfg Config, repo restic.Repository, uid, gid ui
 	rtest.Equals(t, uint32(0), attr.Uid)
 	rtest.Equals(t, uint32(0), attr.Gid)
 }
+
+func TestInodeFromNode(t *testing.T) {
+	node := &restic.Node{Name: "foo.txt", Type: "chardev", Links: 2}
+	ino1 := inodeFromNode(1, node)
+	ino2 := inodeFromNode(2, node)
+	rtest.Assert(t, ino1 == ino2, "inodes %d, %d of hard links differ", ino1, ino2)
+
+	node.Links = 1
+	ino1 = inodeFromNode(1, node)
+	ino2 = inodeFromNode(2, node)
+	rtest.Assert(t, ino1 != ino2, "same inode %d but different parent", ino1)
+}
+
+var sink uint64
+
+func BenchmarkInode(b *testing.B) {
+	for _, sub := range []struct {
+		name string
+		node restic.Node
+	}{
+		{
+			name: "no_hard_links",
+			node: restic.Node{Name: "a somewhat long-ish filename.svg.bz2", Type: "fifo"},
+		},
+		{
+			name: "hard_link",
+			node: restic.Node{Name: "some other filename", Type: "file", Links: 2},
+		},
+	} {
+		b.Run(sub.name, func(b *testing.B) {
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				sink = inodeFromNode(1, &sub.node)
+			}
+		})
+	}
+}

internal/fuse/inode.go

@@ -0,0 +1,44 @@
+//go:build darwin || freebsd || linux
+// +build darwin freebsd linux
+
+package fuse
+
+import (
+	"encoding/binary"
+
+	"github.com/cespare/xxhash/v2"
+	"github.com/restic/restic/internal/restic"
+)
+
+// inodeFromName generates an inode number for a file in a meta dir.
+func inodeFromName(parent uint64, name string) uint64 {
+	inode := parent ^ xxhash.Sum64String(cleanupNodeName(name))
+
+	// Inode 0 is invalid and 1 is the root. Remap those.
+	if inode < 2 {
+		inode += 2
+	}
+	return inode
+}
+
+// inodeFromNode generates an inode number for a file within a snapshot.
+func inodeFromNode(parent uint64, node *restic.Node) (inode uint64) {
+	if node.Links > 1 && node.Type != "dir" {
+		// If node has hard links, give them all the same inode,
+		// irrespective of the parent.
+		var buf [16]byte
+		binary.LittleEndian.PutUint64(buf[:8], node.DeviceID)
+		binary.LittleEndian.PutUint64(buf[8:], node.Inode)
+		inode = xxhash.Sum64(buf[:])
+	} else {
+		// Else, use the name and the parent inode.
+		// node.{DeviceID,Inode} may not even be reliable.
+		inode = parent ^ xxhash.Sum64String(cleanupNodeName(node.Name))
+	}
+
+	// Inode 0 is invalid and 1 is the root. Remap those.
+	if inode < 2 {
+		inode += 2
+	}
+	return inode
+}

internal/fuse/snapshots_dir.go

@@ -78,7 +78,7 @@ func (d *SnapshotsDir) ReadDirAll(ctx context.Context) ([]fuse.Dirent, error) {
 
 	for name, entry := range meta.names {
 		d := fuse.Dirent{
-			Inode: fs.GenerateDynamicInode(d.inode, name),
+			Inode: inodeFromName(d.inode, name),
 			Name:  name,
 			Type:  fuse.DT_Dir,
 		}
@@ -104,12 +104,13 @@ func (d *SnapshotsDir) Lookup(ctx context.Context, name string) (fs.Node, error)
 
 	entry := meta.names[name]
 	if entry != nil {
+		inode := inodeFromName(d.inode, name)
 		if entry.linkTarget != "" {
-			return newSnapshotLink(d.root, fs.GenerateDynamicInode(d.inode, name), entry.linkTarget, entry.snapshot)
+			return newSnapshotLink(d.root, inode, entry.linkTarget, entry.snapshot)
 		} else if entry.snapshot != nil {
-			return newDirFromSnapshot(d.root, fs.GenerateDynamicInode(d.inode, name), entry.snapshot)
+			return newDirFromSnapshot(d.root, inode, entry.snapshot)
 		} else {
-			return NewSnapshotsDir(d.root, fs.GenerateDynamicInode(d.inode, name), d.inode, d.dirStruct, d.prefix+"/"+name), nil
+			return NewSnapshotsDir(d.root, inode, d.inode, d.dirStruct, d.prefix+"/"+name), nil
 		}
 	}