fusefrontend: upgrade wlockMap to use device AND inode number

If there are multiple filesystems backing the gocryptfs filesystems
inode numbers are not guaranteed to be unique.

5 files changed, 63 insertions, 51 deletions

diff --git a/internal/fusefrontend/file.go b/internal/fusefrontend/file.go
index de36a45..44146d6 100644
--- a/internal/fusefrontend/file.go
+++ b/internal/fusefrontend/file.go
@@ -38,8 +38,8 @@ type file struct {
 	writeOnly bool
 	// Content encryption helper
 	contentEnc *contentenc.ContentEnc
-	// Inode number
-	ino uint64
+	// Device and inode number uniquely identify the backing file
+	devIno DevInoStruct
 	// File header
 	header *contentenc.FileHeader
 	// go-fuse nodefs.loopbackFile
@@ -59,13 +59,14 @@ func NewFile(fd *os.File, writeOnly bool, contentEnc *contentenc.ContentEnc) (no
 		tlog.Warn.Printf("NewFile: Fstat on fd %d failed: %v\n", fd.Fd(), err)
 		return nil, fuse.ToStatus(err)
 	}
-	wlock.register(st.Ino)
+	di := DevInoFromStat(&st)
+	wlock.register(di)
 
 	return &file{
 		fd:           fd,
 		writeOnly:    writeOnly,
 		contentEnc:   contentEnc,
-		ino:          st.Ino,
+		devIno:       di,
 		loopbackFile: nodefs.NewLoopbackFile(fd),
 	}, fuse.OK
 }
@@ -109,7 +110,7 @@ func (f *file) createHeader() error {
 	// Prevent partially written (=corrupt) header by preallocating the space beforehand
 	err := syscallcompat.EnospcPrealloc(int(f.fd.Fd()), 0, contentenc.HeaderLen)
 	if err != nil {
-		tlog.Warn.Printf("ino%d: createHeader: prealloc failed: %s\n", f.ino, err.Error())
+		tlog.Warn.Printf("ino%d: createHeader: prealloc failed: %s\n", f.devIno.ino, err.Error())
 		return err
 	}
 
@@ -169,7 +170,7 @@ func (f *file) doRead(off uint64, length uint64) ([]byte, fuse.Status) {
 	plaintext, err := f.contentEnc.DecryptBlocks(ciphertext, firstBlockNo, f.header.ID)
 	if err != nil {
 		curruptBlockNo := firstBlockNo + f.contentEnc.PlainOffToBlockNo(uint64(len(plaintext)))
-		tlog.Warn.Printf("ino%d: doRead: corrupt block #%d: %v", f.ino, curruptBlockNo, err)
+		tlog.Warn.Printf("ino%d: doRead: corrupt block #%d: %v", f.devIno.ino, curruptBlockNo, err)
 		return nil, fuse.EIO
 	}
 
@@ -192,23 +193,23 @@ func (f *file) Read(buf []byte, off int64) (resultData fuse.ReadResult, code fus
 	f.fdLock.RLock()
 	defer f.fdLock.RUnlock()
 
-	tlog.Debug.Printf("ino%d: FUSE Read: offset=%d length=%d", f.ino, len(buf), off)
+	tlog.Debug.Printf("ino%d: FUSE Read: offset=%d length=%d", f.devIno.ino, len(buf), off)
 
 	if f.writeOnly {
-		tlog.Warn.Printf("ino%d: Tried to read from write-only file", f.ino)
+		tlog.Warn.Printf("ino%d: Tried to read from write-only file", f.devIno.ino)
 		return nil, fuse.EBADF
 	}
 
 	out, status := f.doRead(uint64(off), uint64(len(buf)))
 
 	if status == fuse.EIO {
-		tlog.Warn.Printf("ino%d: Read: returning EIO, offset=%d, length=%d", f.ino, len(buf), off)
+		tlog.Warn.Printf("ino%d: Read: returning EIO, offset=%d, length=%d", f.devIno.ino, len(buf), off)
 	}
 	if status != fuse.OK {
 		return nil, status
 	}
 
-	tlog.Debug.Printf("ino%d: Read: status %v, returning %d bytes", f.ino, status, len(out))
+	tlog.Debug.Printf("ino%d: Read: status %v, returning %d bytes", f.devIno.ino, status, len(out))
 	return fuse.ReadResultData(out), status
 }
 
@@ -250,7 +251,7 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
 			var oldData []byte
 			oldData, status = f.doRead(o, f.contentEnc.PlainBS())
 			if status != fuse.OK {
-				tlog.Warn.Printf("ino%d fh%d: RMW read failed: %s", f.ino, f.intFd(), status.String())
+				tlog.Warn.Printf("ino%d fh%d: RMW read failed: %s", f.devIno.ino, f.intFd(), status.String())
 				return written, status
 			}
 			// Modify
@@ -262,12 +263,12 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
 		blockOffset := b.BlockCipherOff()
 		blockData = f.contentEnc.EncryptBlock(blockData, b.BlockNo, f.header.ID)
 		tlog.Debug.Printf("ino%d: Writing %d bytes to block #%d",
-			f.ino, uint64(len(blockData))-f.contentEnc.BlockOverhead(), b.BlockNo)
+			f.devIno.ino, uint64(len(blockData))-f.contentEnc.BlockOverhead(), b.BlockNo)
 
 		// Prevent partially written (=corrupt) blocks by preallocating the space beforehand
 		err := syscallcompat.EnospcPrealloc(int(f.fd.Fd()), int64(blockOffset), int64(len(blockData)))
 		if err != nil {
-			tlog.Warn.Printf("ino%d fh%d: doWrite: prealloc failed: %s", f.ino, f.intFd(), err.Error())
+			tlog.Warn.Printf("ino%d fh%d: doWrite: prealloc failed: %s", f.devIno.ino, f.intFd(), err.Error())
 			status = fuse.ToStatus(err)
 			break
 		}
@@ -289,7 +290,7 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
 // directly (in time and space) follows the last write.
 // This is an optimisation for streaming writes on NFS where a
 // Stat() call is very expensive.
-// The caller must "wlock.lock(f.ino)" otherwise this check would be racy.
+// The caller must "wlock.lock(f.devIno.ino)" otherwise this check would be racy.
 func (f *file) isConsecutiveWrite(off int64) bool {
 	opCount := atomic.LoadUint64(&wlock.opCount)
 	return opCount == f.lastOpCount+1 && off == f.lastWrittenOffset+1
@@ -305,12 +306,12 @@ func (f *file) Write(data []byte, off int64) (uint32, fuse.Status) {
 		// The file descriptor has been closed concurrently, which also means
 		// the wlock has been freed. Exit here so we don't crash trying to access
 		// it.
-		tlog.Warn.Printf("ino%d fh%d: Write on released file", f.ino, f.intFd())
+		tlog.Warn.Printf("ino%d fh%d: Write on released file", f.devIno.ino, f.intFd())
 		return 0, fuse.EBADF
 	}
-	wlock.lock(f.ino)
-	defer wlock.unlock(f.ino)
-	tlog.Debug.Printf("ino%d: FUSE Write: offset=%d length=%d", f.ino, off, len(data))
+	wlock.lock(f.devIno)
+	defer wlock.unlock(f.devIno)
+	tlog.Debug.Printf("ino%d: FUSE Write: offset=%d length=%d", f.devIno.ino, off, len(data))
 	// If the write creates a file hole, we have to zero-pad the last block.
 	// But if the write directly follows an earlier write, it cannot create a
 	// hole, and we can save one Stat() call.
@@ -332,13 +333,13 @@ func (f *file) Write(data []byte, off int64) (uint32, fuse.Status) {
 func (f *file) Release() {
 	f.fdLock.Lock()
 	if f.released {
-		log.Panicf("ino%d fh%d: double release", f.ino, f.intFd())
+		log.Panicf("ino%d fh%d: double release", f.devIno.ino, f.intFd())
 	}
 	f.fd.Close()
 	f.released = true
 	f.fdLock.Unlock()
 
-	wlock.unregister(f.ino)
+	wlock.unregister(f.devIno)
 }
 
 // Flush - FUSE call
diff --git a/internal/fusefrontend/file_allocate_truncate.go b/internal/fusefrontend/file_allocate_truncate.go
index bedbba3..f2fca22 100644
--- a/internal/fusefrontend/file_allocate_truncate.go
+++ b/internal/fusefrontend/file_allocate_truncate.go
@@ -50,8 +50,8 @@ func (f *file) Allocate(off uint64, sz uint64, mode uint32) fuse.Status {
 	if f.released {
 		return fuse.EBADF
 	}
-	wlock.lock(f.ino)
-	defer wlock.unlock(f.ino)
+	wlock.lock(f.devIno)
+	defer wlock.unlock(f.devIno)
 
 	blocks := f.contentEnc.ExplodePlainRange(off, sz)
 	firstBlock := blocks[0]
@@ -97,17 +97,17 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
 	defer f.fdLock.RUnlock()
 	if f.released {
 		// The file descriptor has been closed concurrently.
-		tlog.Warn.Printf("ino%d fh%d: Truncate on released file", f.ino, f.intFd())
+		tlog.Warn.Printf("ino%d fh%d: Truncate on released file", f.devIno.ino, f.intFd())
 		return fuse.EBADF
 	}
-	wlock.lock(f.ino)
-	defer wlock.unlock(f.ino)
+	wlock.lock(f.devIno)
+	defer wlock.unlock(f.devIno)
 	var err error
 	// Common case first: Truncate to zero
 	if newSize == 0 {
 		err = syscall.Ftruncate(int(f.fd.Fd()), 0)
 		if err != nil {
-			tlog.Warn.Printf("ino%d fh%d: Ftruncate(fd, 0) returned error: %v", f.ino, f.intFd(), err)
+			tlog.Warn.Printf("ino%d fh%d: Ftruncate(fd, 0) returned error: %v", f.devIno.ino, f.intFd(), err)
 			return fuse.ToStatus(err)
 		}
 		// Truncate to zero kills the file header
@@ -123,7 +123,7 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
 
 	oldB := float32(oldSize) / float32(f.contentEnc.PlainBS())
 	newB := float32(newSize) / float32(f.contentEnc.PlainBS())
-	tlog.Debug.Printf("ino%d: FUSE Truncate from %.2f to %.2f blocks (%d to %d bytes)", f.ino, oldB, newB, oldSize, newSize)
+	tlog.Debug.Printf("ino%d: FUSE Truncate from %.2f to %.2f blocks (%d to %d bytes)", f.devIno.ino, oldB, newB, oldSize, newSize)
 
 	// File size stays the same - nothing to do
 	if newSize == oldSize {
@@ -166,7 +166,7 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
 func (f *file) statPlainSize() (uint64, error) {
 	fi, err := f.fd.Stat()
 	if err != nil {
-		tlog.Warn.Printf("ino%d fh%d: statPlainSize: %v", f.ino, f.intFd(), err)
+		tlog.Warn.Printf("ino%d fh%d: statPlainSize: %v", f.devIno.ino, f.intFd(), err)
 		return 0, err
 	}
 	cipherSz := uint64(fi.Size())
diff --git a/internal/fusefrontend/write_lock.go b/internal/fusefrontend/write_lock.go
index 3addfd6..71e911e 100644
--- a/internal/fusefrontend/write_lock.go
+++ b/internal/fusefrontend/write_lock.go
@@ -3,10 +3,26 @@ package fusefrontend
 import (
 	"sync"
 	"sync/atomic"
+	"syscall"
 )
 
+// DevInoStruct uniquely identifies a backing file through device number and
+// inode number.
+type DevInoStruct struct {
+	dev uint64
+	ino uint64
+}
+
+func DevInoFromStat(st *syscall.Stat_t) DevInoStruct {
+	// Explicit cast to uint64 to prevent build problems on 32-bit platforms
+	return DevInoStruct{
+		dev: uint64(st.Dev),
+		ino: uint64(st.Ino),
+	}
+}
+
 func init() {
-	wlock.inodeLocks = make(map[uint64]*refCntMutex)
+	wlock.inodeLocks = make(map[DevInoStruct]*refCntMutex)
 }
 
 // wlock - serializes write accesses to each file (identified by inode number)
@@ -29,7 +45,7 @@ type wlockMap struct {
 	opCount uint64
 	// Protects map access
 	sync.Mutex
-	inodeLocks map[uint64]*refCntMutex
+	inodeLocks map[DevInoStruct]*refCntMutex
 }
 
 // refCntMutex - mutex with reference count
@@ -42,45 +58,45 @@ type refCntMutex struct {
 
 // register creates an entry for "ino", or incrementes the reference count
 // if the entry already exists.
-func (w *wlockMap) register(ino uint64) {
+func (w *wlockMap) register(di DevInoStruct) {
 	w.Lock()
 	defer w.Unlock()
 
-	r := w.inodeLocks[ino]
+	r := w.inodeLocks[di]
 	if r == nil {
 		r = &refCntMutex{}
-		w.inodeLocks[ino] = r
+		w.inodeLocks[di] = r
 	}
 	r.refCnt++
 }
 
-// unregister decrements the reference count for "ino" and deletes the entry if
+// unregister decrements the reference count for "di" and deletes the entry if
 // the reference count has reached 0.
-func (w *wlockMap) unregister(ino uint64) {
+func (w *wlockMap) unregister(di DevInoStruct) {
 	w.Lock()
 	defer w.Unlock()
 
-	r := w.inodeLocks[ino]
+	r := w.inodeLocks[di]
 	r.refCnt--
 	if r.refCnt == 0 {
-		delete(w.inodeLocks, ino)
+		delete(w.inodeLocks, di)
 	}
 }
 
-// lock retrieves the entry for "ino" and locks it.
-func (w *wlockMap) lock(ino uint64) {
+// lock retrieves the entry for "di" and locks it.
+func (w *wlockMap) lock(di DevInoStruct) {
 	atomic.AddUint64(&w.opCount, 1)
 	w.Lock()
-	r := w.inodeLocks[ino]
+	r := w.inodeLocks[di]
 	w.Unlock()
 	// this can take a long time - execute outside the wlockMap lock
 	r.Lock()
 }
 
-// unlock retrieves the entry for "ino" and unlocks it.
-func (w *wlockMap) unlock(ino uint64) {
+// unlock retrieves the entry for "di" and unlocks it.
+func (w *wlockMap) unlock(di DevInoStruct) {
 	w.Lock()
-	r := w.inodeLocks[ino]
+	r := w.inodeLocks[di]
 	w.Unlock()
 	r.Unlock()
 }
diff --git a/internal/fusefrontend_reverse/ino_map.go b/internal/fusefrontend_reverse/ino_map.go
index 9412343..dae8222 100644
--- a/internal/fusefrontend_reverse/ino_map.go
+++ b/internal/fusefrontend_reverse/ino_map.go
@@ -17,8 +17,3 @@ type inoGenT struct {
 func (i *inoGenT) next() uint64 {
 	return atomic.AddUint64(i.ino, 1)
 }
-
-type devIno struct {
-	dev uint64
-	ino uint64
-}
diff --git a/internal/fusefrontend_reverse/rfs.go b/internal/fusefrontend_reverse/rfs.go
index 7f102cf..aca4b90 100644
--- a/internal/fusefrontend_reverse/rfs.go
+++ b/internal/fusefrontend_reverse/rfs.go
@@ -41,7 +41,7 @@ type ReverseFS struct {
 	// Inode number generator
 	inoGen *inoGenT
 	// Maps backing files device+inode pairs to user-facing unique inode numbers
-	inoMap map[devIno]uint64
+	inoMap map[fusefrontend.DevInoStruct]uint64
 	// Protects map access
 	inoMapLock sync.Mutex
 }
@@ -68,7 +68,7 @@ func NewFS(args fusefrontend.Args) *ReverseFS {
 		nameTransform: nameTransform,
 		contentEnc:    contentEnc,
 		inoGen:        newInoGen(),
-		inoMap:        map[devIno]uint64{},
+		inoMap:        map[fusefrontend.DevInoStruct]uint64{},
 	}
 }
 
@@ -167,7 +167,7 @@ func (rfs *ReverseFS) inoAwareStat(relPlainPath string) (*fuse.Attr, fuse.Status
 	// The file has hard links. We have to give it a stable inode number so
 	// tar or rsync can find them.
 	if fi.Mode().IsRegular() && st.Nlink > 1 {
-		di := devIno{uint64(st.Dev), st.Ino}
+		di := fusefrontend.DevInoFromStat(st)
 		rfs.inoMapLock.Lock()
 		stableIno := rfs.inoMap[di]
 		if stableIno == 0 {