Merge branch 'y/nodefs-cancel' into t

* y/nodefs-cancel:
  Y nodefs: Propagate context to File methods
  fuse: dump WRITE argument in debug logs
  Make pollHack work on read-only mounts
  example: loopback: implement -ro flag
  fs: add TestRoMount
  posixtest: add DirSeek test, Go port of xfstests generic/257
  fs: bridge: implement simple directory seeking
  fs: cleanup after TestForget

.gitignore

@@ -12,3 +12,5 @@ example/loopback/loopback
 example/multizip/multizip
 example/bulkstat/bulkstat
 example/zipfs/zipfs
+# test binaries
+*.test

example/loopback/main.go

@@ -46,6 +46,7 @@ func main() {
 	debug := flag.Bool("debug", false, "print debugging messages.")
 	other := flag.Bool("allow-other", false, "mount with -o allowother.")
 	quiet := flag.Bool("q", false, "quiet")
+	ro := flag.Bool("ro", false, "mount read-only")
 	cpuprofile := flag.String("cpuprofile", "", "write cpu profile to this file")
 	memprofile := flag.String("memprofile", "", "write memory profile to this file")
 	flag.Parse()
@@ -100,6 +101,9 @@ func main() {
 		// Make the kernel check file permissions for us
 		opts.MountOptions.Options = append(opts.MountOptions.Options, "default_permissions")
 	}
+	if *ro {
+		opts.MountOptions.Options = append(opts.MountOptions.Options, "ro")
+	}
 	// First column in "df -T": original dir
 	opts.MountOptions.Options = append(opts.MountOptions.Options, "fsname="+orig)
 	// Second column in "df -T" will be shown as "fuse." + Name

fs/bridge.go

@@ -33,6 +33,12 @@ type fileEntry struct {
 	dirStream   DirStream
 	hasOverflow bool
 	overflow    fuse.DirEntry
+	// dirOffset is the current location in the directory (see `telldir(3)`).
+	// The value is equivalent to `d_off` (see `getdents(2)`) of the last
+	// directory entry sent to the kernel so far.
+	// If `dirOffset` and `fuse.DirEntryList.offset` disagree, then a
+	// directory seek has taken place.
+	dirOffset uint64
 
 	wg sync.WaitGroup
 }
@@ -842,23 +848,47 @@ func (b *rawBridge) OpenDir(cancel <-chan struct{}, input *fuse.OpenIn, out *fus
 	return fuse.OK
 }
 
-// setStream sets the directory part of f. Must hold f.mu
-func (b *rawBridge) setStream(cancel <-chan struct{}, input *fuse.ReadIn, inode *Inode, f *fileEntry) syscall.Errno {
-	if f.dirStream == nil || input.Offset == 0 {
+// setStream makes sure `f.dirStream` and associated state variables are set and
+// seeks to offset requested in `input`. Caller must hold `f.mu`.
+// The `eof` return value shows if `f.dirStream` ended before the requested
+// offset was reached.
+func (b *rawBridge) setStream(cancel <-chan struct{}, input *fuse.ReadIn, inode *Inode, f *fileEntry) (errno syscall.Errno, eof bool) {
+	// Get a new directory stream in the following cases:
+	// 1) f.dirStream == nil ............ First READDIR[PLUS] on this file handle.
+	// 2) input.Offset == 0 ............. Start reading the directory again from
+	//                                    the beginning (user called rewinddir(3) or lseek(2)).
+	// 3) input.Offset < f.nextOffset ... Seek back (user called seekdir(3) or lseek(2)).
+	if f.dirStream == nil || input.Offset == 0 || input.Offset < f.dirOffset {
 		if f.dirStream != nil {
 			f.dirStream.Close()
 			f.dirStream = nil
 		}
 		str, errno := b.getStream(&fuse.Context{Caller: input.Caller, Cancel: cancel}, inode)
 		if errno != 0 {
-			return errno
+			return errno, false
 		}
 
+		f.dirOffset = 0
 		f.hasOverflow = false
 		f.dirStream = str
 	}
 
-	return 0
+	// Seek forward?
+	for f.dirOffset < input.Offset {
+		f.hasOverflow = false
+		if !f.dirStream.HasNext() {
+			// Seek past end of directory. This is not an error, but the
+			// user will get an empty directory listing.
+			return 0, true
+		}
+		_, errno := f.dirStream.Next()
+		if errno != 0 {
+			return errno, true
+		}
+		f.dirOffset++
+	}
+
+	return 0, false
 }
 
 func (b *rawBridge) getStream(ctx context.Context, inode *Inode) (DirStream, syscall.Errno) {
@@ -880,14 +910,19 @@ func (b *rawBridge) ReadDir(cancel <-chan struct{}, input *fuse.ReadIn, out *fus
 
 	f.mu.Lock()
 	defer f.mu.Unlock()
-	if errno := b.setStream(cancel, input, n, f); errno != 0 {
+
+	errno, eof := b.setStream(cancel, input, n, f)
+	if errno != 0 {
 		return errnoToStatus(errno)
+	} else if eof {
+		return fuse.OK
 	}
 
 	if f.hasOverflow {
 		// always succeeds.
 		out.AddDirEntry(f.overflow)
 		f.hasOverflow = false
+		f.dirOffset++
 	}
 
 	for f.dirStream.HasNext() {
@@ -901,6 +936,7 @@ func (b *rawBridge) ReadDir(cancel <-chan struct{}, input *fuse.ReadIn, out *fus
 			f.hasOverflow = true
 			return errnoToStatus(errno)
 		}
+		f.dirOffset++
 	}
 
 	return fuse.OK
@@ -911,8 +947,12 @@ func (b *rawBridge) ReadDirPlus(cancel <-chan struct{}, input *fuse.ReadIn, out
 
 	f.mu.Lock()
 	defer f.mu.Unlock()
-	if errno := b.setStream(cancel, input, n, f); errno != 0 {
+
+	errno, eof := b.setStream(cancel, input, n, f)
+	if errno != 0 {
 		return errnoToStatus(errno)
+	} else if eof {
+		return fuse.OK
 	}
 
 	ctx := &fuse.Context{Caller: input.Caller, Cancel: cancel}
@@ -937,6 +977,7 @@ func (b *rawBridge) ReadDirPlus(cancel <-chan struct{}, input *fuse.ReadIn, out
 			f.hasOverflow = true
 			return fuse.OK
 		}
+		f.dirOffset++
 
 		// Virtual entries "." and ".." should be part of the
 		// directory listing, but not part of the filesystem tree.

fs/forget_test.go

@@ -83,13 +83,14 @@ func TestForget(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	defer os.RemoveAll(dir)
 
 	rawFS := NewNodeFS(root, options)
 	server, err := fuse.NewServer(rawFS, dir, &options.MountOptions)
 	if err != nil {
 		t.Fatal(err)
 	}
-
+	defer server.Unmount()
 	go server.Serve()
 	if err := server.WaitMount(); err != nil {
 		t.Fatal(err)

fs/loopback_linux_test.go

@@ -380,3 +380,8 @@ func TestParallelDiropsHang(t *testing.T) {
 	wg.Wait()
 	server.Unmount()
 }
+
+func TestRoMount(t *testing.T) {
+	tc := newTestCase(t, &testOptions{ro: true})
+	defer tc.Clean()
+}

fs/simple_test.go

@@ -53,6 +53,7 @@ type testOptions struct {
 	attrCache     bool
 	suppressDebug bool
 	testDir       string
+	ro            bool
 }
 
 // newTestCase creates the directories `orig` and `mnt` inside a temporary
@@ -102,6 +103,9 @@ func newTestCase(t *testing.T, opts *testOptions) *testCase {
 	if !opts.suppressDebug {
 		mOpts.Debug = testutil.VerboseTest()
 	}
+	if opts.ro {
+		mOpts.Options = append(mOpts.Options, "ro")
+	}
 	tc.server, err = fuse.NewServer(tc.rawFS, tc.mntDir, mOpts)
 	if err != nil {
 		t.Fatal(err)

fuse/direntry.go

@@ -36,10 +36,17 @@ func (d DirEntry) String() string {
 // DirEntryList holds the return value for READDIR and READDIRPLUS
 // opcodes.
 type DirEntryList struct {
-	buf        []byte
-	size       int      // capacity of the underlying buffer
-	offset     uint64   // entry count (NOT a byte offset)
-	lastDirent *_Dirent // pointer to the last serialized _Dirent. Used by FixMode().
+	buf []byte
+	// capacity of the underlying buffer
+	size int
+	// offset is the requested location in the directory. go-fuse
+	// currently counts in number of directory entries, but this is an
+	// implementation detail and may change in the future.
+	// If `offset` and `fs.fileEntry.dirOffset` disagree, then a
+	// directory seek has taken place.
+	offset uint64
+	// pointer to the last serialized _Dirent. Used by FixMode().
+	lastDirent *_Dirent
 }
 
 // NewDirEntryList creates a DirEntryList with the given data buffer

fuse/poll.go

@@ -15,24 +15,19 @@ func doPollHackLookup(ms *Server, req *request) {
 		Nlink: 1,
 	}
 	switch req.inHeader.Opcode {
-	case _OP_CREATE:
-		out := (*CreateOut)(req.outData())
-		out.EntryOut = EntryOut{
+	case _OP_LOOKUP:
+		out := (*EntryOut)(req.outData())
+		*out = EntryOut{
 			NodeId: pollHackInode,
 			Attr:   attr,
 		}
-		out.OpenOut = OpenOut{
+		req.status = OK
+	case _OP_OPEN:
+		out := (*OpenOut)(req.outData())
+		*out = OpenOut{
 			Fh: pollHackInode,
 		}
 		req.status = OK
-	case _OP_LOOKUP:
-		out := (*EntryOut)(req.outData())
-		*out = EntryOut{}
-		req.status = ENOENT
-	case _OP_GETATTR:
-		out := (*AttrOut)(req.outData())
-		out.Attr = attr
-		req.status = OK
 	case _OP_POLL:
 		req.status = ENOSYS
 	default:

fuse/poll_linux.go

@@ -8,7 +8,7 @@ import (
 )
 
 func pollHack(mountPoint string) error {
-	fd, err := syscall.Creat(filepath.Join(mountPoint, pollHackName), syscall.O_CREAT)
+	fd, err := syscall.Open(filepath.Join(mountPoint, pollHackName), syscall.O_RDONLY, 0)
 	if err != nil {
 		return err
 	}

fuse/request.go

@@ -90,14 +90,19 @@ func (r *request) InputDebug() string {
 		names = fmt.Sprintf("%q", r.filenames)
 	}
 
-	if len(r.arg) > 0 {
-		l := len(r.arg)
-		s := ""
-		if l > debugDataDumpMax {
-			l = debugDataDumpMax
-			s = "..."
+	if l := len(r.arg); l > 0 {
+		data := ""
+		if len(r.filenames) == 0 {
+			dots := ""
+			if l > debugDataDumpMax {
+				l = debugDataDumpMax
+				dots = "..."
+			}
+
+			data = fmt.Sprintf("%q%s", r.arg[:l], dots)
 		}
-		names += fmt.Sprintf(" %db %q%s", len(r.arg), r.arg[:l], s)
+
+		names += fmt.Sprintf("%s %db", data, len(r.arg))
 	}
 
 	return fmt.Sprintf("rx %d: %s i%d %s%s",

posixtest/test.go

@@ -40,6 +40,7 @@ var All = map[string]func(*testing.T, string){
 	"DirectIO":                   DirectIO,
 	"OpenAt":                     OpenAt,
 	"Fallocate":                  Fallocate,
+	"DirSeek":                    DirSeek,
 }
 
 func DirectIO(t *testing.T, mnt string) {

posixtest/xfstests.go

+package posixtest
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"syscall"
+	"testing"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+// DirSeek tests that seeking on a directory works for
+// https://github.com/hanwen/go-fuse/issues/344 .
+//
+// Go port of xfstests generic/257.
+//
+// Hint:
+// $ go test ./fs -run TestPosix/DirSeek -v
+func DirSeek(t *testing.T, mnt string) {
+	// From bash script xfstests/tests/generic/257
+	ttt := mnt + "/ttt"
+	err := os.Mkdir(ttt, 0700)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for i := 1; i <= 168; i++ {
+		path := fmt.Sprintf("%s/%d", ttt, i)
+		err = ioutil.WriteFile(path, nil, 0600)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	// From C app xfstests/src/t_dir_offset2.c
+	const bufSize = 4096
+	const historyLen = 1024
+	offHistory := make([]int64, historyLen)
+	inoHistory := make([]uint64, historyLen)
+	buf := make([]byte, bufSize)
+	fd, err := syscall.Open(ttt, syscall.O_RDONLY|syscall.O_DIRECTORY, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer syscall.Close(fd)
+
+	total := 0
+	for {
+		n, err := unix.Getdents(fd, buf)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if n == 0 {
+			break
+		}
+		for bpos := 0; bpos < n; total++ {
+			d := (*unix.Dirent)(unsafe.Pointer(&buf[bpos]))
+			if total > historyLen {
+				t.Fatal("too many files")
+			}
+			for i := 0; i < total; i++ {
+				if offHistory[i] == d.Off {
+					t.Errorf("entries %d and %d gave duplicate d.Off %d",
+						i, total, d.Off)
+				}
+			}
+			offHistory[total] = d.Off
+			inoHistory[total] = d.Ino
+			bpos += int(d.Reclen)
+		}
+	}
+
+	// check if seek works correctly
+	d := (*unix.Dirent)(unsafe.Pointer(&buf[0]))
+	for i := total - 1; i >= 0; i-- {
+		var seekTo int64
+		if i > 0 {
+			seekTo = offHistory[i-1]
+		}
+		_, err = unix.Seek(fd, seekTo, os.SEEK_SET)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		n, err := unix.Getdents(fd, buf)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if n == 0 {
+			t.Errorf("getdents returned 0 on entry %d", i)
+			continue
+		}
+
+		if d.Ino != inoHistory[i] {
+			t.Errorf("entry %d has inode %d, expected %d",
+				i, d.Ino, inoHistory[i])
+		}
+	}
+}