Fix: prevent panic when swap file creation fails (#7957)

* Fix: prevent panic when swap file creation fails

* weed mount: fix race condition in swap file initialization

Ensure thread-safe access to sf.file and other state in NewSwapFileChunk
and FreeResource by using sf.chunkTrackingLock consistently. Also
set sf.file to nil after closing to prevent reuse.

* weed mount: improve swap directory creation logic

- Check error for os.MkdirAll and log it if it fails.
- Use 0700 permissions for the swap directory for better security.
- Improve error logging context.

* weed mount: add unit tests for swap file creation

Add tests to verify:
- Concurrent initialization of the swap file.
- Correct directory permissions (0700).
- Automatic directory recreation if deleted.

* weed mount: fix thread-safety in swap file unit tests

Use atomic.Uint32 to track failures within goroutines in
TestSwapFile_NewSwapFileChunk_Concurrent to avoid unsafe calls to
t.Errorf from multiple goroutines.

* weed mount: simplify swap file creation logic

Refactor the directory check and retry logic for better readability and
to avoid re-using the main error variable for directory creation errors.
Remove redundant error logging.

* weed mount: improve error checking in swap file tests

Explicitly check if NewSwapFileChunk returns nil to provide more
informative failures.

* weed mount: update DirtyPages interface to return error

Propagate errors from SaveDataAt when swap file creation fails. This
prevents potential panics in the write path.

* weed mount: handle AddPage errors in write paths

Update ChunkedDirtyPages and PageWriter to propagate errors and update
WFS.Write and WFS.CopyFileRange to return fuse.EIO on failure.

* weed mount: update swap directory creation error message

Change "recreate" to "create/recreate" to better reflect that this path
is also taken during the initial creation of the swap directory.

---------

Co-authored-by: lixiang58 <lixiang58@lenovo.com>
Co-authored-by: Chris Lu <chris.lu@gmail.com>

weed/mount/dirty_pages_chunked.go

@@ -38,13 +38,13 @@ func newMemoryChunkPages(fh *FileHandle, chunkSize int64) *ChunkedDirtyPages {
 	return dirtyPages
 }
 
-func (pages *ChunkedDirtyPages) AddPage(offset int64, data []byte, isSequential bool, tsNs int64) {
+func (pages *ChunkedDirtyPages) AddPage(offset int64, data []byte, isSequential bool, tsNs int64) error {
 	pages.hasWrites = true
 
 	glog.V(4).Infof("%v memory AddPage [%d, %d)", pages.fh.fh, offset, offset+int64(len(data)))
-	pages.uploadPipeline.SaveDataAt(data, offset, isSequential, tsNs)
+	_, err := pages.uploadPipeline.SaveDataAt(data, offset, isSequential, tsNs)
 
-	return
+	return err
 }
 
 func (pages *ChunkedDirtyPages) FlushData() error {

weed/mount/page_writer.go

@@ -29,21 +29,24 @@ func newPageWriter(fh *FileHandle, chunkSize int64) *PageWriter {
 	return pw
 }
 
-func (pw *PageWriter) AddPage(offset int64, data []byte, isSequential bool, tsNs int64) {
+func (pw *PageWriter) AddPage(offset int64, data []byte, isSequential bool, tsNs int64) 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)
-		pw.addToOneChunk(i, offset, data[:writeSize], isSequential, tsNs)
+		if err := pw.addToOneChunk(i, offset, data[:writeSize], isSequential, tsNs); err != nil {
+			return err
+		}
 		offset += writeSize
 		data = data[writeSize:]
 	}
+	return nil
 }
 
-func (pw *PageWriter) addToOneChunk(chunkIndex, offset int64, data []byte, isSequential bool, tsNs int64) {
-	pw.randomWriter.AddPage(offset, data, isSequential, tsNs)
+func (pw *PageWriter) addToOneChunk(chunkIndex, offset int64, data []byte, isSequential bool, tsNs int64) error {
+	return pw.randomWriter.AddPage(offset, data, isSequential, tsNs)
 }
 
 func (pw *PageWriter) FlushData() error {

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)
+	AddPage(offset int64, data []byte, isSequential bool, tsNs int64) error
 	FlushData() error
 	ReadDirtyDataAt(data []byte, startOffset int64, tsNs int64) (maxStop int64)
 	Destroy()

weed/mount/page_writer/page_chunk_swapfile.go

@@ -1,12 +1,13 @@
 package page_writer
 
 import (
-	"github.com/seaweedfs/seaweedfs/weed/glog"
-	"github.com/seaweedfs/seaweedfs/weed/util"
-	"github.com/seaweedfs/seaweedfs/weed/util/mem"
 	"io"
 	"os"
 	"sync"
+
+	"github.com/seaweedfs/seaweedfs/weed/glog"
+	"github.com/seaweedfs/seaweedfs/weed/util"
+	"github.com/seaweedfs/seaweedfs/weed/util/mem"
 )
 
 var (
@@ -42,23 +43,34 @@ func NewSwapFile(dir string, chunkSize int64) *SwapFile {
 	}
 }
 func (sf *SwapFile) FreeResource() {
+	sf.chunkTrackingLock.Lock()
+	defer sf.chunkTrackingLock.Unlock()
 	if sf.file != nil {
 		sf.file.Close()
 		os.Remove(sf.file.Name())
+		sf.file = nil
 	}
 }
 
 func (sf *SwapFile) NewSwapFileChunk(logicChunkIndex LogicChunkIndex) (tc *SwapFileChunk) {
+	sf.chunkTrackingLock.Lock()
+	defer sf.chunkTrackingLock.Unlock()
+
 	if sf.file == nil {
 		var err error
 		sf.file, err = os.CreateTemp(sf.dir, "")
+		if os.IsNotExist(err) {
+			if mkdirErr := os.MkdirAll(sf.dir, 0700); mkdirErr != nil {
+				glog.Errorf("create/recreate swap directory %s: %v", sf.dir, mkdirErr)
+				return nil
+			}
+			sf.file, err = os.CreateTemp(sf.dir, "")
+		}
 		if err != nil {
-			glog.Errorf("create swap file: %v", err)
+			glog.Errorf("create swap file in %s: %v", sf.dir, err)
 			return nil
 		}
 	}
-	sf.chunkTrackingLock.Lock()
-	defer sf.chunkTrackingLock.Unlock()
 
 	sf.activeChunkCount++
 

weed/mount/page_writer/page_chunk_swapfile_test.go

@@ -0,0 +1,105 @@
+package page_writer
+
+import (
+	"os"
+	"path/filepath"
+	"sync"
+	"sync/atomic"
+	"testing"
+)
+
+func TestSwapFile_NewSwapFileChunk_Concurrent(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "seaweedfs_swap_test")
+	if err != nil {
+		t.Fatalf("failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	sf := NewSwapFile(filepath.Join(tempDir, "swap"), 1024)
+	defer sf.FreeResource()
+
+	var wg sync.WaitGroup
+	var failures atomic.Uint32
+	numConcurrent := 10
+	for i := 0; i < numConcurrent; i++ {
+		wg.Add(1)
+		go func(idx int) {
+			defer wg.Done()
+			chunk := sf.NewSwapFileChunk(LogicChunkIndex(idx))
+			if chunk == nil {
+				failures.Add(1)
+			}
+		}(i)
+	}
+	wg.Wait()
+
+	if failures.Load() > 0 {
+		t.Errorf("failed to create %d chunks", failures.Load())
+	}
+
+	if sf.file == nil {
+		t.Error("sf.file should not be nil")
+	}
+}
+
+func TestSwapFile_MkdirAll_Permissions(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "seaweedfs_swap_perm_test")
+	if err != nil {
+		t.Fatalf("failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	swapDir := filepath.Join(tempDir, "swap_subdir")
+	sf := NewSwapFile(swapDir, 1024)
+	defer sf.FreeResource()
+
+	// This should trigger os.MkdirAll
+	if sf.NewSwapFileChunk(0) == nil {
+		t.Fatal("NewSwapFileChunk failed to create a chunk")
+	}
+
+	info, err := os.Stat(swapDir)
+	if err != nil {
+		t.Fatalf("failed to stat swap dir: %v", err)
+	}
+
+	if !info.IsDir() {
+		t.Errorf("expected %s to be a directory", swapDir)
+	}
+
+	// Check permissions - should be 0700
+	if info.Mode().Perm() != 0700 {
+		t.Errorf("expected permissions 0700, got %o", info.Mode().Perm())
+	}
+}
+
+func TestSwapFile_RecreateDir(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "seaweedfs_swap_recreate_test")
+	if err != nil {
+		t.Fatalf("failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	swapDir := filepath.Join(tempDir, "swap_recreate")
+	sf := NewSwapFile(swapDir, 1024)
+
+	// Create first chunk
+	if sf.NewSwapFileChunk(0) == nil {
+		t.Fatal("NewSwapFileChunk failed to create the first chunk")
+	}
+	sf.FreeResource()
+
+	// Delete the directory
+	os.RemoveAll(swapDir)
+
+	// Create second chunk - should recreate directory
+	chunk := sf.NewSwapFileChunk(1)
+	if chunk == nil {
+		t.Error("failed to create chunk after directory deletion")
+	}
+
+	if _, err := os.Stat(swapDir); os.IsNotExist(err) {
+		t.Error("swap directory was not recreated")
+	}
+	sf.FreeResource()
+}

weed/mount/page_writer/upload_pipeline.go

@@ -2,10 +2,11 @@ package page_writer
 
 import (
 	"fmt"
-	"github.com/seaweedfs/seaweedfs/weed/glog"
-	"github.com/seaweedfs/seaweedfs/weed/util"
 	"sync"
 	"sync/atomic"
+
+	"github.com/seaweedfs/seaweedfs/weed/glog"
+	"github.com/seaweedfs/seaweedfs/weed/util"
 )
 
 type LogicChunkIndex int
@@ -55,7 +56,7 @@ func NewUploadPipeline(writers *util.LimitedConcurrentExecutor, chunkSize int64,
 	return t
 }
 
-func (up *UploadPipeline) SaveDataAt(p []byte, off int64, isSequential bool, tsNs int64) (n int) {
+func (up *UploadPipeline) SaveDataAt(p []byte, off int64, isSequential bool, tsNs int64) (n int, err error) {
 
 	up.chunksLock.Lock()
 	defer up.chunksLock.Unlock()
@@ -103,6 +104,9 @@ func (up *UploadPipeline) SaveDataAt(p []byte, off int64, isSequential bool, tsN
 		} else {
 			pageChunk = up.swapFile.NewSwapFileChunk(logicChunkIndex)
 			// fmt.Printf(" create file chunk %d\n", logicChunkIndex)
+			if pageChunk == nil {
+				return 0, fmt.Errorf("failed to create swap file chunk")
+			}
 		}
 		up.writableChunks[logicChunkIndex] = pageChunk
 	}

weed/mount/page_writer/upload_pipeline_test.go

@@ -1,8 +1,9 @@
 package page_writer
 
 import (
-	"github.com/seaweedfs/seaweedfs/weed/util"
 	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/util"
 )
 
 func TestUploadPipeline(t *testing.T) {

weed/mount/weedfs_file_copy_range.go

@@ -128,11 +128,14 @@ func (wfs *WFS) CopyFileRange(cancel <-chan struct{}, in *fuse.CopyFileRangeIn)
 
 		// Perform the write
 		fhOut.dirtyPages.writerPattern.MonitorWriteAt(offsetOut, int(numBytesRead))
-		fhOut.dirtyPages.AddPage(
+		if err := fhOut.dirtyPages.AddPage(
 			offsetOut,
 			buff[:numBytesRead],
 			fhOut.dirtyPages.writerPattern.IsSequentialMode(),
-			nowUnixNano)
+			nowUnixNano); err != nil {
+			glog.Errorf("AddPage error: %v", err)
+			return 0, fuse.EIO
+		}
 
 		// Accumulate for the next loop iteration
 		totalCopied += numBytesRead

weed/mount/weedfs_file_write.go

@@ -1,11 +1,13 @@
 package mount
 
 import (
-	"github.com/hanwen/go-fuse/v2/fuse"
-	"github.com/seaweedfs/seaweedfs/weed/util"
 	"net/http"
 	"syscall"
 	"time"
+
+	"github.com/hanwen/go-fuse/v2/fuse"
+	"github.com/seaweedfs/seaweedfs/weed/glog"
+	"github.com/seaweedfs/seaweedfs/weed/util"
 )
 
 /**
@@ -72,7 +74,10 @@ func (wfs *WFS) Write(cancel <-chan struct{}, in *fuse.WriteIn, data []byte) (wr
 
 	// glog.V(4).Infof("%v write [%d,%d) %d", fh.f.fullpath(), req.Offset, req.Offset+int64(len(req.Data)), len(req.Data))
 
-	fh.dirtyPages.AddPage(offset, data, fh.dirtyPages.writerPattern.IsSequentialMode(), tsNs)
+	if err := fh.dirtyPages.AddPage(offset, data, fh.dirtyPages.writerPattern.IsSequentialMode(), tsNs); err != nil {
+		glog.Errorf("AddPage error: %v", err)
+		return 0, fuse.EIO
+	}
 
 	written = uint32(len(data))