add support for fallocate (#66)

* Fallocate support

* use fallocate wrapper that works on darwin

conversions.go

@@ -546,6 +546,21 @@ func convertInMessage(
 			Value: value,
 			Flags: in.Flags,
 		}
+	case fusekernel.OpFallocate:
+		type input fusekernel.FallocateIn
+		in := (*input)(inMsg.Consume(unsafe.Sizeof(input{})))
+		if in == nil {
+			err = errors.New("Corrupt OpFallocate")
+			return
+		}
+
+		o = &fuseops.FallocateOp{
+			Inode:  fuseops.InodeID(inMsg.Header().Nodeid),
+			Handle: fuseops.HandleID(in.Fh),
+			Offset: in.Offset,
+			Length: in.Length,
+			Mode:   in.Mode,
+		}
 
 	default:
 		o = &unknownOp{
@@ -793,6 +808,9 @@ func (c *Connection) kernelResponseForOp(
 	case *fuseops.SetXattrOp:
 		// Empty response
 
+	case *fuseops.FallocateOp:
+		// Empty response
+
 	case *initOp:
 		out := (*fusekernel.InitOut)(m.Grow(int(unsafe.Sizeof(fusekernel.InitOut{}))))
 

debug.go

@@ -98,6 +98,11 @@ func describeRequest(op interface{}) (s string) {
 
 	case *fuseops.SetXattrOp:
 		addComponent("name %s", typed.Name)
+
+	case *fuseops.FallocateOp:
+		addComponent("offset %d", typed.Offset)
+		addComponent("length %d", typed.Length)
+		addComponent("mode %d", typed.Mode)
 	}
 
 	// Use just the name if there is no extra info.

fuseops/ops.go

@@ -865,3 +865,22 @@ type SetXattrOp struct {
 	// simply replace the value if the attribute exists.
 	Flags uint32
 }
+
+type FallocateOp struct {
+	// The inode and handle we are fallocating
+	Inode  InodeID
+	Handle HandleID
+
+	// Start of the byte range
+	Offset uint64
+
+	// Length of the byte range
+	Length uint64
+
+	// If Mode is 0x0, allocate disk space within the range specified
+	// If Mode has 0x1, allocate the space but don't increase the file size
+	// If Mode has 0x2, deallocate space within the range specified
+	// If Mode has 0x2, it sbould also have 0x1 (deallocate should not increase
+	// file size)
+	Mode uint32
+}

fuseutil/file_system.go

@@ -61,6 +61,7 @@ type FileSystem interface {
 	GetXattr(context.Context, *fuseops.GetXattrOp) error
 	ListXattr(context.Context, *fuseops.ListXattrOp) error
 	SetXattr(context.Context, *fuseops.SetXattrOp) error
+	Fallocate(context.Context, *fuseops.FallocateOp) error
 
 	// Regard all inodes (including the root inode) as having their lookup counts
 	// decremented to zero, and clean up any resources associated with the file
@@ -215,6 +216,9 @@ func (s *fileSystemServer) handleOp(
 
 	case *fuseops.SetXattrOp:
 		err = s.fs.SetXattr(ctx, typed)
+
+	case *fuseops.FallocateOp:
+		err = s.fs.Fallocate(ctx, typed)
 	}
 
 	c.Reply(ctx, err)

fuseutil/not_implemented_file_system.go

@@ -219,5 +219,12 @@ func (fs *NotImplementedFileSystem) SetXattr(
 	return
 }
 
+func (fs *NotImplementedFileSystem) Fallocate(
+	ctx context.Context,
+	op *fuseops.FallocateOp) (err error) {
+	err = fuse.ENOSYS
+	return
+}
+
 func (fs *NotImplementedFileSystem) Destroy() {
 }

internal/fusekernel/fuse_kernel.go

@@ -380,6 +380,7 @@ const (
 	OpDestroy     = 38
 	OpIoctl       = 39 // Linux?
 	OpPoll        = 40 // Linux?
+	OpFallocate   = 43
 
 	// OS X
 	OpSetvolname = 61
@@ -665,6 +666,14 @@ type ListxattrIn struct {
 	Padding uint32
 }
 
+type FallocateIn struct {
+	Fh      uint64
+	Offset  uint64
+	Length  uint64
+	Mode    uint32
+	Padding uint32
+}
+
 type LkIn struct {
 	Fh      uint64
 	Owner   uint64

samples/memfs/inode.go

@@ -20,6 +20,7 @@ import (
 	"os"
 	"time"
 
+	"github.com/jacobsa/fuse"
 	"github.com/jacobsa/fuse/fuseops"
 	"github.com/jacobsa/fuse/fuseutil"
 )
@@ -382,3 +383,18 @@ func (in *inode) SetAttributes(
 		in.attrs.Mtime = *mtime
 	}
 }
+
+func (in *inode) Fallocate(mode uint32, offset uint64, length uint64) (
+	err error) {
+	if mode == 0 {
+		newSize := int(offset + length)
+		if newSize > len(in.contents) {
+			padding := make([]byte, newSize-len(in.contents))
+			in.contents = append(in.contents, padding...)
+			in.attrs.Size = offset + length
+		}
+	} else {
+		err = fuse.ENOSYS
+	}
+	return
+}

samples/memfs/memfs.go

@@ -753,3 +753,12 @@ func (fs *memFS) SetXattr(ctx context.Context,
 
 	return
 }
+
+func (fs *memFS) Fallocate(ctx context.Context,
+	op *fuseops.FallocateOp) (err error) {
+	fs.mu.Lock()
+	defer fs.mu.Unlock()
+	inode := fs.getInodeOrDie(op.Inode)
+	inode.Fallocate(op.Mode, op.Length, op.Length)
+	return
+}

samples/memfs/memfs_test.go

@@ -28,6 +28,7 @@ import (
 	"testing"
 	"time"
 
+	fallocate "github.com/detailyang/go-fallocate"
 	"github.com/jacobsa/fuse"
 	"github.com/jacobsa/fuse/fusetesting"
 	"github.com/jacobsa/fuse/samples"
@@ -1955,3 +1956,31 @@ func (t *MknodTest) NonExistentParent() {
 	err = syscall.Mknod(p, syscall.S_IFREG|0600, 0)
 	ExpectEq(syscall.ENOENT, err)
 }
+
+func (t *MknodTest) Fallocate_Larger() {
+	var err error
+	fileName := path.Join(t.Dir, "foo")
+
+	// Create a file.
+	err = ioutil.WriteFile(fileName, []byte("taco"), 0600)
+	AssertEq(nil, err)
+
+	// Open it for modification.
+	f, err := os.OpenFile(fileName, os.O_RDWR, 0)
+	t.ToClose = append(t.ToClose, f)
+	AssertEq(nil, err)
+
+	// Truncate it.
+	err = fallocate.Fallocate(f, 5, 1)
+	AssertEq(nil, err)
+
+	// Stat it.
+	fi, err := f.Stat()
+	AssertEq(nil, err)
+	ExpectEq(6, fi.Size())
+
+	// Read the contents.
+	contents, err := ioutil.ReadFile(fileName)
+	AssertEq(nil, err)
+	ExpectEq("taco\x00\x00", string(contents))
+}