mount: fail the write when the swap file chunk cannot be created (#12655)

* mount: fail the write when the swap file chunk cannot be created

#7957 added a nil check after NewSwapFileChunk so a failed swap file
creation returns an error instead of panicking. The result was assigned
to pageChunk, a PageChunk interface, before the check, and an interface
holding a nil *SwapFileChunk is not nil, so the check never fired:
SaveDataAt stored the nil chunk and panicked in WriteDataAt.

Check the *SwapFileChunk before converting it. The new test points the
swap directory below a regular file; on master it panics in
SwapFileChunk.WriteDataAt.

Signed-off-by: anant <170962632+antcybersec@users.noreply.github.com>

* mount: grow the file only after its write is buffered

Write set the new size, times, pending append offset and uncommitted
bytes before AddPage. When AddPage failed (now that a swap file chunk
that cannot be created returns an error), the write was reported as
failed but the larger size stayed on the handle's entry, so the next
flush published it with a hole where the data should be.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* mount: report a partly buffered write as a short write

PageWriter.AddPage fills one chunk at a time, so when a later chunk
cannot be created the earlier chunks already hold their bytes. Return
how much was buffered, and let Write grow the size and times over that
prefix and report it, instead of failing the whole write while the
prefix still reaches the next flush.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* mount: report the bytes a failed copy_file_range already buffered

A streaming copy whose page fails partway returned an error even though
earlier pages, or the start of the failing one, were already buffered and
would reach the next flush with the destination size left short. Count
the buffered bytes, grow the destination over them, and return them as a
short copy.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* mount: free the copy test's destination pages

The buffered memory chunk counts toward the process-wide memory chunk
ceiling, so repeated runs of the test pushed later ones onto the
unusable swap directory.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* mount: count only the bytes a swap chunk stored

A swap chunk whose file write fails stores a prefix or nothing, but
SaveDataAt returned no error and AddPage counted the whole span as
buffered. SaveDataAt now reports the short write, and AddPage passes the
stored count up so a write is never acknowledged past it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* mount: fail a partly buffered writeback write

Kernel writeback ignores the count in a WRITE reply, so a short write
there drops the unbuffered rest without an error. A write flagged as
page-cache writeback now keeps its buffered prefix but returns the
error, which the kernel reports on fsync.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Signed-off-by: anant <170962632+antcybersec@users.noreply.github.com>
Co-authored-by: anant <170962632+antcybersec@users.noreply.github.com>
Co-authored-by: Chris Lu <chrislusf@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

weed/mount/dirty_pages_chunked.go

@@ -54,19 +54,17 @@ func newMemoryChunkPages(fh *FileHandle, chunkSize int64) *ChunkedDirtyPages {
 	return dirtyPages
 }
 
-func (pages *ChunkedDirtyPages) AddPage(offset int64, data []byte, isSequential bool, tsNs int64) error {
+func (pages *ChunkedDirtyPages) AddPage(offset int64, data []byte, isSequential bool, tsNs int64) (n int, err error) {
 	// A failed chunk upload already dropped its data, so this handle can never
 	// flush cleanly. Reject further writes so the writer fails fast instead of
 	// pushing the rest of the file through a pipeline that cannot persist it.
 	if err := pages.LastError(); err != nil {
-		return err
+		return 0, err
 	}
 	pages.hasWrites = true
 
 	glog.V(4).Infof("%v memory AddPage [%d, %d)", pages.fh.fh, offset, offset+int64(len(data)))
-	_, err := pages.uploadPipeline.SaveDataAt(data, offset, isSequential, tsNs)
-
-	return err
+	return pages.uploadPipeline.SaveDataAt(data, offset, isSequential, tsNs)
 }
 
 func (pages *ChunkedDirtyPages) HasWrites() bool {

weed/mount/dirty_pages_chunked_test.go

@@ -32,7 +32,7 @@ func TestChunkedDirtyPagesFailWritesAfterUploadError(t *testing.T) {
 	uploadErr := errors.New("assign volume failure: no writable volumes")
 	pages.setLastError(uploadErr)
 
-	if err := pages.AddPage(0, []byte("x"), true, 1); !errors.Is(err, uploadErr) {
+	if _, err := pages.AddPage(0, []byte("x"), true, 1); !errors.Is(err, uploadErr) {
 		t.Fatalf("AddPage after upload failure = %v, want sticky %v", err, uploadErr)
 	}
 	if err := pages.FlushData(); !errors.Is(err, uploadErr) {

weed/mount/page_writer.go

@@ -15,10 +15,6 @@ type PageWriter struct {
 	randomWriter page_writer.DirtyPages
 }
 
-var (
-	_ = page_writer.DirtyPages(&PageWriter{})
-)
-
 func newPageWriter(fh *FileHandle, chunkSize int64) *PageWriter {
 	pw := &PageWriter{
 		fh:            fh,
@@ -29,23 +25,27 @@ func newPageWriter(fh *FileHandle, chunkSize int64) *PageWriter {
 	return pw
 }
 
-func (pw *PageWriter) AddPage(offset int64, data []byte, isSequential bool, tsNs int64) error {
+// AddPage returns how many leading bytes of data it buffered; on error those
+// bytes stay buffered.
+func (pw *PageWriter) AddPage(offset int64, data []byte, isSequential bool, tsNs int64) (buffered int64, err error) {
 
 	glog.V(4).Infof("%v AddPage [%d, %d)", pw.fh.fh, offset, offset+int64(len(data)))
 
 	chunkIndex := offset / pw.chunkSize
 	for i := chunkIndex; len(data) > 0; i++ {
 		writeSize := min(int64(len(data)), (i+1)*pw.chunkSize-offset)
-		if err := pw.addToOneChunk(i, offset, data[:writeSize], isSequential, tsNs); err != nil {
-			return err
+		n, err := pw.addToOneChunk(i, offset, data[:writeSize], isSequential, tsNs)
+		buffered += int64(n)
+		if err != nil {
+			return buffered, err
 		}
 		offset += writeSize
 		data = data[writeSize:]
 	}
-	return nil
+	return buffered, nil
 }
 
-func (pw *PageWriter) addToOneChunk(chunkIndex, offset int64, data []byte, isSequential bool, tsNs int64) error {
+func (pw *PageWriter) addToOneChunk(chunkIndex, offset int64, data []byte, isSequential bool, tsNs int64) (int, error) {
 	return pw.randomWriter.AddPage(offset, data, isSequential, tsNs)
 }
 

weed/mount/page_writer/dirty_pages.go

@@ -1,7 +1,7 @@
 package page_writer
 
 type DirtyPages interface {
-	AddPage(offset int64, data []byte, isSequential bool, tsNs int64) error
+	AddPage(offset int64, data []byte, isSequential bool, tsNs int64) (n int, err error)
 	FlushData() error
 	HasWrites() bool
 	ReadDirtyDataAt(data []byte, startOffset int64, tsNs int64) (maxStop int64)

weed/mount/page_writer/upload_pipeline.go

@@ -2,6 +2,7 @@ package page_writer
 
 import (
 	"fmt"
+	"io"
 	"math"
 	"sync"
 	"sync/atomic"
@@ -144,12 +145,15 @@ func (up *UploadPipeline) SaveDataAt(p []byte, off int64, isSequential bool, tsN
 			pageChunk = NewMemChunk(logicChunkIndex, up.ChunkSize)
 			// fmt.Printf(" create mem  chunk %d\n", logicChunkIndex)
 		} else {
-			pageChunk = up.swapFile.NewSwapFileChunk(logicChunkIndex)
+			// Check the *SwapFileChunk before it becomes a PageChunk: a nil
+			// pointer inside the interface would not compare equal to nil.
+			swapChunk := up.swapFile.NewSwapFileChunk(logicChunkIndex)
 			// fmt.Printf(" create file chunk %d\n", logicChunkIndex)
-			if pageChunk == nil {
+			if swapChunk == nil {
 				up.accountant.Release(up.ChunkSize)
 				return 0, fmt.Errorf("failed to create swap file chunk")
 			}
+			pageChunk = swapChunk
 		}
 		up.writableChunks[logicChunkIndex] = pageChunk
 	}
@@ -161,6 +165,9 @@ func (up *UploadPipeline) SaveDataAt(p []byte, off int64, isSequential bool, tsN
 	//}
 	n = pageChunk.WriteDataAt(p, off, tsNs)
 	up.maybeMoveToSealed(pageChunk, logicChunkIndex)
+	if n < len(p) {
+		err = fmt.Errorf("chunk %d stored %d of %d bytes: %w", logicChunkIndex, n, len(p), io.ErrShortWrite)
+	}
 
 	return
 }

weed/mount/page_writer/upload_pipeline_swap_test.go

@@ -0,0 +1,56 @@
+package page_writer
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// When the swap file cannot be created, SaveDataAt must fail the write
+// instead of keeping a nil swap chunk and writing through it, and give back
+// the write budget it reserved for the chunk.
+func TestSaveDataAtFailsWhenSwapFileCannotBeCreated(t *testing.T) {
+	for _, tc := range []struct {
+		name       string
+		accountant *WriteBufferAccountant
+	}{
+		{name: "no write budget"},
+		{name: "write budget", accountant: NewWriteBufferAccountant(1 << 20)},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			notADir := filepath.Join(t.TempDir(), "file")
+			if err := os.WriteFile(notADir, nil, 0600); err != nil {
+				t.Fatal(err)
+			}
+			up := NewUploadPipeline(nil, 1024, nil, 16, filepath.Join(notADir, "swap"), tc.accountant)
+
+			// A write that is not sequential goes to the swap file.
+			n, err := up.SaveDataAt([]byte("data"), 0, false, 0)
+			if err == nil {
+				t.Fatalf("SaveDataAt = %d, nil; want an error", n)
+			}
+			if _, found := up.writableChunks[0]; found {
+				t.Error("the failed write left a writable chunk behind")
+			}
+			if used := tc.accountant.Used(); used != 0 {
+				t.Errorf("write budget still holds %d bytes", used)
+			}
+		})
+	}
+}
+
+// A swap chunk whose file write fails stores nothing, so SaveDataAt must
+// report the short write instead of claiming the bytes.
+func TestSaveDataAtReportsFailedSwapWrite(t *testing.T) {
+	up := NewUploadPipeline(nil, 1024, nil, 16, t.TempDir(), nil)
+	defer up.Shutdown()
+	if n, err := up.SaveDataAt([]byte("data"), 0, false, 0); err != nil || n != 4 {
+		t.Fatalf("first write = %d, %v", n, err)
+	}
+	if err := up.swapFile.file.Close(); err != nil {
+		t.Fatal(err)
+	}
+	if n, err := up.SaveDataAt([]byte("more"), 4, false, 0); err == nil || n != 0 {
+		t.Fatalf("write through a closed swap file = %d, %v; want 0 and an error", n, err)
+	}
+}

weed/mount/weedfs_file_copy_range.go

@@ -180,19 +180,23 @@ func (wfs *WFS) CopyFileRange(cancel <-chan struct{}, in *fuse.CopyFileRangeIn)
 
 		// Perform the write
 		fhOut.dirtyPages.writerPattern.MonitorWriteAt(offsetOut, int(numBytesRead))
-		if err := fhOut.dirtyPages.AddPage(
+		buffered, err := fhOut.dirtyPages.AddPage(
 			offsetOut,
 			buff[:numBytesRead],
 			fhOut.dirtyPages.writerPattern.IsSequentialMode(),
-			nowUnixNano); err != nil {
+			nowUnixNano)
+		if buffered > 0 {
+			fhOut.pageWrites.Add(1)
+			totalCopied += buffered
+			fhOut.dirtyContent = true
+		}
+		if err != nil {
 			glog.Errorf("AddPage error: %v", err)
-			return 0, writeErrorToFuseStatus(err)
+			if totalCopied == 0 {
+				return 0, writeErrorToFuseStatus(err)
+			}
+			break
 		}
-		fhOut.pageWrites.Add(1)
-
-		// Accumulate for the next loop iteration
-		totalCopied += numBytesRead
-		fhOut.dirtyContent = true
 	}
 
 	if totalCopied == 0 {

weed/mount/weedfs_file_copy_range_test.go

@@ -1,8 +1,10 @@
 package mount
 
 import (
+	"bytes"
 	"context"
 	"errors"
+	"os"
 	"path/filepath"
 	"testing"
 
@@ -408,6 +410,47 @@ func TestStreamingCopyMarksOnlyAcceptedContentDirty(t *testing.T) {
 	}
 }
 
+// Bytes the copy buffered before a page failed stay in the handle, so the
+// copy reports them and grows the destination over them.
+func TestStreamingCopyReportsPartlyBufferedCopy(t *testing.T) {
+	wfs := newCopyRangeTestWFS()
+	wfs.option.ConcurrentWriters = 1
+	notADir := filepath.Join(t.TempDir(), "file")
+	if err := os.WriteFile(notADir, nil, 0600); err != nil {
+		t.Fatal(err)
+	}
+	wfs.option.uniqueCacheDirForWrite = filepath.Join(notADir, "swap")
+	srcInode := wfs.inodeToPath.Lookup(util.FullPath("/src.txt"), 1, false, false, 0, true)
+	dstInode := wfs.inodeToPath.Lookup(util.FullPath("/dst.txt"), 1, false, false, 0, true)
+	srcHandle, _, _, _ := wfs.fhMap.AcquireFileHandle(wfs, srcInode, &filer_pb.Entry{
+		Name:       "src.txt",
+		Attributes: &filer_pb.FuseAttributes{FileMode: 0100644, FileSize: 1024, Inode: srcInode},
+		Content:    bytes.Repeat([]byte{'s'}, 1024),
+	}, 0, 0)
+	dstHandle, _, _, _ := wfs.fhMap.AcquireFileHandle(wfs, dstInode, &filer_pb.Entry{
+		Name:       "dst.txt",
+		Attributes: &filer_pb.FuseAttributes{FileMode: 0100644, Inode: dstInode},
+	}, 0, 0)
+	t.Cleanup(dstHandle.dirtyPages.Destroy)
+
+	// The destination range crosses into a second chunk, which needs the swap file.
+	written, status := wfs.CopyFileRange(make(chan struct{}), &fuse.CopyFileRangeIn{
+		FhIn:   uint64(srcHandle.fh),
+		FhOut:  uint64(dstHandle.fh),
+		OffOut: 512,
+		Len:    1024,
+	})
+	if status != fuse.OK || written != 512 {
+		t.Fatalf("CopyFileRange = %d, %v; want a short copy of 512", written, status)
+	}
+	if size := dstHandle.GetEntry().GetEntry().GetAttributes().GetFileSize(); size != 1024 {
+		t.Fatalf("destination size = %d, want 1024", size)
+	}
+	if !dstHandle.dirtyContent || !dstHandle.dirtyMetadata {
+		t.Fatal("the buffered prefix must leave the destination dirty")
+	}
+}
+
 func TestServerSideCopySkipsFencedDestination(t *testing.T) {
 	wfs := newCopyRangeTestWFS()
 	wfs.option.WritebackCache = true

weed/mount/weedfs_file_mkrm_test.go

@@ -270,7 +270,7 @@ func TestTruncateEntryClearsDirtyPagesForOpenHandle(t *testing.T) {
 	fh, _, _, _ := wfs.fhMap.AcquireFileHandle(wfs, inode, entry, 0, 0)
 	fh.RememberPath(fullPath)
 
-	if err := fh.dirtyPages.AddPage(0, []byte("hello"), true, time.Now().UnixNano()); err != nil {
+	if _, err := fh.dirtyPages.AddPage(0, []byte("hello"), true, time.Now().UnixNano()); err != nil {
 		t.Fatalf("AddPage: %v", err)
 	}
 	oldDirtyPages := fh.dirtyPages

weed/mount/weedfs_file_write.go

@@ -68,6 +68,21 @@ func (wfs *WFS) Write(cancel <-chan struct{}, in *fuse.WriteIn, data []byte) (wr
 		return 0, fuse.OK
 	}
 
+	// Size and times cover only the bytes buffered, or the next flush
+	// publishes a hole where the data should be. A partly buffered write
+	// is reported as a short write, or as an error to kernel writeback,
+	// which ignores the count.
+	offset := int64(in.Offset)
+	buffered, err := fh.dirtyPages.AddPage(offset, data, fh.dirtyPages.writerPattern.IsSequentialMode(), tsNs)
+	if err != nil {
+		glog.Errorf("AddPage error: %v", err)
+		if buffered == 0 {
+			return 0, writeErrorToFuseStatus(err)
+		}
+		data = data[:buffered]
+	}
+	fh.pageWrites.Add(1)
+
 	// Only an append past all locally owned bytes needs the stored EOF guard.
 	if in.Offset > entry.Attributes.FileSize && wfs.isAppendWrite(in) {
 		if !fh.pendingAppend || in.Offset < fh.pendingAppendOffset {
@@ -76,7 +91,6 @@ func (wfs *WFS) Write(cancel <-chan struct{}, in *fuse.WriteIn, data []byte) (wr
 		fh.pendingAppend = true
 	}
 	entry.Content = nil
-	offset := int64(in.Offset)
 	oldFileSize := int64(entry.Attributes.FileSize)
 	newFileSize := max(offset+int64(len(data)), oldFileSize)
 	entry.Attributes.FileSize = uint64(newFileSize)
@@ -96,14 +110,6 @@ func (wfs *WFS) Write(cancel <-chan struct{}, in *fuse.WriteIn, data []byte) (wr
 		wfs.AddUncommittedBytes(newFileSize - oldFileSize)
 	}
 
-	// glog.V(4).Infof("%v write [%d,%d) %d", fh.f.fullpath(), req.Offset, req.Offset+int64(len(req.Data)), len(req.Data))
-
-	if err := fh.dirtyPages.AddPage(offset, data, fh.dirtyPages.writerPattern.IsSequentialMode(), tsNs); err != nil {
-		glog.Errorf("AddPage error: %v", err)
-		return 0, writeErrorToFuseStatus(err)
-	}
-	fh.pageWrites.Add(1)
-
 	written = uint32(len(data))
 
 	if offset == 0 {
@@ -127,5 +133,8 @@ func (wfs *WFS) Write(cancel <-chan struct{}, in *fuse.WriteIn, data []byte) (wr
 		fh.mirrorFile.WriteAt(data, offset)
 	}
 
+	if err != nil && in.WriteFlags&fuse.WRITE_CACHE != 0 {
+		return 0, writeErrorToFuseStatus(err)
+	}
 	return written, fuse.OK
 }

weed/mount/weedfs_file_write_test.go

@@ -0,0 +1,95 @@
+//go:build !freebsd
+
+package mount
+
+import (
+	"bytes"
+	"context"
+	"os"
+	"path/filepath"
+	"syscall"
+	"testing"
+
+	"github.com/seaweedfs/go-fuse/v2/fuse"
+	"github.com/seaweedfs/seaweedfs/weed/filer"
+	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
+	"github.com/seaweedfs/seaweedfs/weed/util"
+	"google.golang.org/protobuf/proto"
+)
+
+// A write the swap file cannot buffer fails, and must not grow the file: the
+// next flush would publish that size with a hole where its data should be. A
+// write that buffers only its first chunk is a short write of those bytes, or
+// an error for kernel writeback, which would drop the rest silently.
+func TestFailedWriteDoesNotGrowFile(t *testing.T) {
+	t.Run("short write", func(t *testing.T) { testFailedWriteDoesNotGrowFile(t, 0) })
+	t.Run("kernel writeback", func(t *testing.T) { testFailedWriteDoesNotGrowFile(t, fuse.WRITE_CACHE) })
+}
+
+func testFailedWriteDoesNotGrowFile(t *testing.T, writeFlags uint32) {
+	base := attributeAppendEntry(1)
+	base.CommitTsNs = 100
+	peer := &g6ConditionalPeer{entry: proto.Clone(base).(*filer_pb.Entry)}
+	peer.blobs = map[string][]byte{base.Chunks[0].GetFileIdString(): bytes.Repeat([]byte{'O'}, 256)}
+
+	w := newInvalidateTestWFS(t)
+	notADir := filepath.Join(t.TempDir(), "file")
+	if err := os.WriteFile(notADir, nil, 0600); err != nil {
+		t.Fatal(err)
+	}
+	w.option.uniqueCacheDirForWrite = filepath.Join(notADir, "swap")
+	w.option.DefaultPermissions = true
+	w.posixLocks = NewPosixLockTable()
+	w.option.ConcurrentWriters = 1
+	w.concurrentWriters = util.NewLimitedConcurrentExecutor(1)
+	startFakeFiler(t, w, peer)
+	w.inodeToPath.Lookup("/dir", 1, true, false, 0, false)
+	w.inodeToPath.Lookup("/dir/file", 1, false, false, 42, true)
+	w.inodeToPath.MarkChildrenCached("/dir")
+	if err := w.metaCache.InsertEntry(context.Background(), filer.FromPbEntry("/dir", proto.Clone(base).(*filer_pb.Entry)), 1); err != nil {
+		t.Fatal(err)
+	}
+	out := &fuse.OpenOut{}
+	if code := w.Open(nil, &fuse.OpenIn{InHeader: fuse.InHeader{NodeId: 42}, Flags: syscall.O_WRONLY}, out); code != fuse.OK {
+		t.Fatal(code)
+	}
+	fh := w.GetHandle(FileHandleId(out.Fh))
+	g6AppendUploader(t, fh, 100, peer)
+
+	write := func(offset uint64, size int, value byte) (uint32, fuse.Status) {
+		return w.Write(nil, &fuse.WriteIn{InHeader: fuse.InHeader{NodeId: 42}, Fh: out.Fh, Offset: offset, Size: uint32(size), WriteFlags: writeFlags}, bytes.Repeat([]byte{value}, size))
+	}
+	if _, code := write(256, 256, 'A'); code != fuse.OK {
+		t.Fatalf("buffered write: %v", code)
+	}
+	// The only writable chunk slot is taken, so this write needs the swap file.
+	if _, code := write(4096, 256, 'B'); code == fuse.OK {
+		t.Fatal("write through an unusable swap directory succeeded")
+	}
+	if size := fh.GetEntry().GetEntry().Attributes.FileSize; size != 512 {
+		t.Fatalf("file size after the failed write = %d, want 512", size)
+	}
+	// The first 24 bytes fit the existing chunk; the next chunk needs the swap file.
+	n, code := write(1000, 48, 'C')
+	if writeFlags == 0 && (code != fuse.OK || n != 24) {
+		t.Fatalf("boundary-crossing write = %d, %v; want a short write of 24", n, code)
+	}
+	if writeFlags != 0 && code == fuse.OK {
+		t.Fatalf("boundary-crossing writeback = %d, OK; want an error", n)
+	}
+	if size := fh.GetEntry().GetEntry().Attributes.FileSize; size != 1024 {
+		t.Fatalf("file size after the short write = %d, want 1024", size)
+	}
+	if code := w.Fsync(nil, &fuse.FsyncIn{InHeader: fuse.InHeader{NodeId: 42}, Fh: out.Fh}); code != fuse.OK {
+		t.Fatal(code)
+	}
+
+	peer.mu.Lock()
+	defer peer.mu.Unlock()
+	want := append(bytes.Repeat([]byte{'O'}, 256), bytes.Repeat([]byte{'A'}, 256)...)
+	want = append(want, make([]byte, 1000-512)...)
+	want = append(want, bytes.Repeat([]byte{'C'}, 24)...)
+	if got := g6StoredBytes(t, peer); peer.entry.Attributes.FileSize != 1024 || !bytes.Equal(got, want) {
+		t.Fatalf("stored size %d, want 1024 with the original and buffered bytes", peer.entry.Attributes.FileSize)
+	}
+}

weed/mount/weedfs_flush_deadline_test.go

@@ -121,7 +121,7 @@ func newSlowDataFlush(t *testing.T, assignDelay, deadline time.Duration, stuckCo
 		Chunks:     stored,
 	}, 0, 0)
 	t.Cleanup(func() { wfs.ReleaseHandle(fh.fh) })
-	if err := fh.dirtyPages.AddPage(offset, data, true, time.Now().UnixNano()); err != nil {
+	if _, err := fh.dirtyPages.AddPage(offset, data, true, time.Now().UnixNano()); err != nil {
 		t.Fatalf("AddPage: %v", err)
 	}
 	fh.dirtyMetadata = true