Add pid in all fuse ops (#92)

Expose PID as metadata in CreateFile, OpenFile and FlushFile operations This will help us with kahing/goofys#273 Co-authored-by: Sai Teja Suram <pratap130492@gmail.com> Co-authored-by: Sai Teja Suram <pts@avah.dev>
2 years ago · 36e01f1b3a
parent f8927095af
commit 36e01f1b3a
6 changed files with 250 additions and 79 deletions
--- a/conversions.go
+++ b/conversions.go
@ -50,13 +50,15 @@ func convertInMessage(
 		}

 		o = &fuseops.LookUpInodeOp{
-			Parent: fuseops.InodeID(inMsg.Header().Nodeid),
-			Name:   string(buf[:n-1]),
+			Parent:    fuseops.InodeID(inMsg.Header().Nodeid),
+			Name:      string(buf[:n-1]),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpGetattr:
 		o = &fuseops.GetInodeAttributesOp{
-			Inode: fuseops.InodeID(inMsg.Header().Nodeid),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpSetattr:
@ -67,7 +69,8 @@ func convertInMessage(
 		}

 		to := &fuseops.SetInodeAttributesOp{
-			Inode: fuseops.InodeID(inMsg.Header().Nodeid),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}
 		o = to

@ -104,8 +107,9 @@ func convertInMessage(
 		}

 		o = &fuseops.ForgetInodeOp{
-			Inode: fuseops.InodeID(inMsg.Header().Nodeid),
-			N:     in.Nlookup,
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			N:         in.Nlookup,
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpMkdir:
@ -131,7 +135,8 @@ func convertInMessage(
 			// the fact that this is a directory is implicit in the fact that the
 			// opcode is mkdir. But we want the correct mode to go through, so ensure
 			// that os.ModeDir is set.
-			Mode: convertFileMode(in.Mode) | os.ModeDir,
+			Mode:      convertFileMode(in.Mode) | os.ModeDir,
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpMknod:
@ -148,9 +153,10 @@ func convertInMessage(
 		name = name[:i]

 		o = &fuseops.MkNodeOp{
-			Parent: fuseops.InodeID(inMsg.Header().Nodeid),
-			Name:   string(name),
-			Mode:   convertFileMode(in.Mode),
+			Parent:    fuseops.InodeID(inMsg.Header().Nodeid),
+			Name:      string(name),
+			Mode:      convertFileMode(in.Mode),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpCreate:
@ -167,9 +173,10 @@ func convertInMessage(
 		name = name[:i]

 		o = &fuseops.CreateFileOp{
-			Parent: fuseops.InodeID(inMsg.Header().Nodeid),
-			Name:   string(name),
-			Mode:   convertFileMode(in.Mode),
+			Parent:    fuseops.InodeID(inMsg.Header().Nodeid),
+			Name:      string(name),
+			Mode:      convertFileMode(in.Mode),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpSymlink:
@ -185,9 +192,10 @@ func convertInMessage(
 		newName, target := names[0:i], names[i+1:len(names)-1]

 		o = &fuseops.CreateSymlinkOp{
-			Parent: fuseops.InodeID(inMsg.Header().Nodeid),
-			Name:   string(newName),
-			Target: string(target),
+			Parent:    fuseops.InodeID(inMsg.Header().Nodeid),
+			Name:      string(newName),
+			Target:    string(target),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpRename:
@ -216,6 +224,7 @@ func convertInMessage(
 			OldName:   string(oldName),
 			NewParent: fuseops.InodeID(in.Newdir),
 			NewName:   string(newName),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpUnlink:
@ -226,8 +235,9 @@ func convertInMessage(
 		}

 		o = &fuseops.UnlinkOp{
-			Parent: fuseops.InodeID(inMsg.Header().Nodeid),
-			Name:   string(buf[:n-1]),
+			Parent:    fuseops.InodeID(inMsg.Header().Nodeid),
+			Name:      string(buf[:n-1]),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpRmdir:
@ -238,18 +248,21 @@ func convertInMessage(
 		}

 		o = &fuseops.RmDirOp{
-			Parent: fuseops.InodeID(inMsg.Header().Nodeid),
-			Name:   string(buf[:n-1]),
+			Parent:    fuseops.InodeID(inMsg.Header().Nodeid),
+			Name:      string(buf[:n-1]),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpOpen:
 		o = &fuseops.OpenFileOp{
-			Inode: fuseops.InodeID(inMsg.Header().Nodeid),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpOpendir:
 		o = &fuseops.OpenDirOp{
-			Inode: fuseops.InodeID(inMsg.Header().Nodeid),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpRead:
@ -259,9 +272,10 @@ func convertInMessage(
 		}

 		to := &fuseops.ReadFileOp{
-			Inode:  fuseops.InodeID(inMsg.Header().Nodeid),
-			Handle: fuseops.HandleID(in.Fh),
-			Offset: int64(in.Offset),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			Handle:    fuseops.HandleID(in.Fh),
+			Offset:    int64(in.Offset),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}
 		o = to

@ -283,9 +297,10 @@ func convertInMessage(
 		}

 		to := &fuseops.ReadDirOp{
-			Inode:  fuseops.InodeID(inMsg.Header().Nodeid),
-			Handle: fuseops.HandleID(in.Fh),
-			Offset: fuseops.DirOffset(in.Offset),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			Handle:    fuseops.HandleID(in.Fh),
+			Offset:    fuseops.DirOffset(in.Offset),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}
 		o = to

@ -308,7 +323,8 @@ func convertInMessage(
 		}

 		o = &fuseops.ReleaseFileHandleOp{
-			Handle: fuseops.HandleID(in.Fh),
+			Handle:    fuseops.HandleID(in.Fh),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpReleasedir:
@ -319,7 +335,8 @@ func convertInMessage(
 		}

 		o = &fuseops.ReleaseDirHandleOp{
-			Handle: fuseops.HandleID(in.Fh),
+			Handle:    fuseops.HandleID(in.Fh),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpWrite:
@ -334,10 +351,11 @@ func convertInMessage(
 		}

 		o = &fuseops.WriteFileOp{
-			Inode:  fuseops.InodeID(inMsg.Header().Nodeid),
-			Handle: fuseops.HandleID(in.Fh),
-			Data:   buf,
-			Offset: int64(in.Offset),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			Handle:    fuseops.HandleID(in.Fh),
+			Data:      buf,
+			Offset:    int64(in.Offset),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpFsync:
@ -348,8 +366,9 @@ func convertInMessage(
 		}

 		o = &fuseops.SyncFileOp{
-			Inode:  fuseops.InodeID(inMsg.Header().Nodeid),
-			Handle: fuseops.HandleID(in.Fh),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			Handle:    fuseops.HandleID(in.Fh),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpFlush:
@ -360,13 +379,15 @@ func convertInMessage(
 		}

 		o = &fuseops.FlushFileOp{
-			Inode:  fuseops.InodeID(inMsg.Header().Nodeid),
-			Handle: fuseops.HandleID(in.Fh),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			Handle:    fuseops.HandleID(in.Fh),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpReadlink:
 		o = &fuseops.ReadSymlinkOp{
-			Inode: fuseops.InodeID(inMsg.Header().Nodeid),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpStatfs:
@ -414,9 +435,10 @@ func convertInMessage(
 		}

 		o = &fuseops.CreateLinkOp{
-			Parent: fuseops.InodeID(inMsg.Header().Nodeid),
-			Name:   string(name),
-			Target: fuseops.InodeID(in.Oldnodeid),
+			Parent:    fuseops.InodeID(inMsg.Header().Nodeid),
+			Name:      string(name),
+			Target:    fuseops.InodeID(in.Oldnodeid),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpRemovexattr:
@ -427,8 +449,9 @@ func convertInMessage(
 		}

 		o = &fuseops.RemoveXattrOp{
-			Inode: fuseops.InodeID(inMsg.Header().Nodeid),
-			Name:  string(buf[:n-1]),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			Name:      string(buf[:n-1]),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	case fusekernel.OpGetxattr:
@ -446,8 +469,9 @@ func convertInMessage(
 		name = name[:i]

 		to := &fuseops.GetXattrOp{
-			Inode: fuseops.InodeID(inMsg.Header().Nodeid),
-			Name:  string(name),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			Name:      string(name),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}
 		o = to

@ -470,7 +494,8 @@ func convertInMessage(
 		}

 		to := &fuseops.ListXattrOp{
-			Inode: fuseops.InodeID(inMsg.Header().Nodeid),
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}
 		o = to

@ -505,10 +530,11 @@ func convertInMessage(
 		name, value := payload[:i], payload[i+1:len(payload)]

 		o = &fuseops.SetXattrOp{
-			Inode: fuseops.InodeID(inMsg.Header().Nodeid),
-			Name:  string(name),
-			Value: value,
-			Flags: in.Flags,
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			Name:      string(name),
+			Value:     value,
+			Flags:     in.Flags,
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}
 	case fusekernel.OpFallocate:
 		type input fusekernel.FallocateIn
@ -518,11 +544,12 @@ func convertInMessage(
 		}

 		o = &fuseops.FallocateOp{
-			Inode:  fuseops.InodeID(inMsg.Header().Nodeid),
-			Handle: fuseops.HandleID(in.Fh),
-			Offset: in.Offset,
-			Length: in.Length,
-			Mode:   in.Mode,
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			Handle:    fuseops.HandleID(in.Fh),
+			Offset:    in.Offset,
+			Length:    in.Length,
+			Mode:      in.Mode,
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
 		}

 	default:
--- a/debug.go
+++ b/debug.go
@ -55,6 +55,12 @@ func describeRequest(op interface{}) (s string) {
 		addComponent("name %q", f.Interface())
 	}

+	if f := v.FieldByName("OpContext"); f.IsValid() {
+		if meta, ok := f.Interface().(fuseops.OpContext); ok {
+			addComponent("PID %+v", meta.Pid)
+		}
+	}
+
 	// Handle special cases.
 	switch typed := op.(type) {
 	case *interruptOp:
--- a/fuseops/ops.go
+++ b/fuseops/ops.go
@ -23,6 +23,14 @@ import (
 // File system
 ////////////////////////////////////////////////////////////////////////

+// OpContext contains extra context that may be needed by some file systems.
+// See https://libfuse.github.io/doxygen/structfuse__context.html as a reference.
+type OpContext struct {
+	// PID of the process that is invoking the operation.
+	// Not filled in case of a writepage operation.
+	Pid uint32
+}
+
 // Return statistics about the file system's capacity and available resources.
 //
 // Called by statfs(2) and friends:
@ -119,7 +127,8 @@ type LookUpInodeOp struct {
 	//
 	// The lookup count for the inode is implicitly incremented. See notes on
 	// ForgetInodeOp for more information.
-	Entry ChildInodeEntry
+	Entry     ChildInodeEntry
+	OpContext OpContext
 }

 // Refresh the attributes for an inode whose ID was previously returned in a
@ -135,6 +144,7 @@ type GetInodeAttributesOp struct {
 	// more.
 	Attributes           InodeAttributes
 	AttributesExpiration time.Time
+	OpContext            OpContext
 }

 // Change attributes for an inode.
@ -159,6 +169,7 @@ type SetInodeAttributesOp struct {
 	// ChildInodeEntry.AttributesExpiration for more.
 	Attributes           InodeAttributes
 	AttributesExpiration time.Time
+	OpContext            OpContext
 }

 // Decrement the reference count for an inode ID previously issued by the file
@ -205,7 +216,8 @@ type ForgetInodeOp struct {
 	Inode InodeID

 	// The amount to decrement the reference count.
-	N uint64
+	N         uint64
+	OpContext OpContext
 }

 ////////////////////////////////////////////////////////////////////////
@ -235,7 +247,8 @@ type MkDirOp struct {
 	//
 	// The lookup count for the inode is implicitly incremented. See notes on
 	// ForgetInodeOp for more information.
-	Entry ChildInodeEntry
+	Entry     ChildInodeEntry
+	OpContext OpContext
 }

 // Create a file inode as a child of an existing directory inode. The kernel
@ -262,7 +275,8 @@ type MkNodeOp struct {
 	//
 	// The lookup count for the inode is implicitly incremented. See notes on
 	// ForgetInodeOp for more information.
-	Entry ChildInodeEntry
+	Entry     ChildInodeEntry
+	OpContext OpContext
 }

 // Create a file inode and open it.
@ -298,6 +312,7 @@ type CreateFileOp struct {
 	// file handle. The file system must ensure this ID remains valid until a
 	// later call to ReleaseFileHandle.
 	Handle HandleID
+	OpContext OpContext
 }

 // Create a symlink inode. If the name already exists, the file system should
@ -317,7 +332,8 @@ type CreateSymlinkOp struct {
 	//
 	// The lookup count for the inode is implicitly incremented. See notes on
 	// ForgetInodeOp for more information.
-	Entry ChildInodeEntry
+	Entry     ChildInodeEntry
+	OpContext OpContext
 }

 // Create a hard link to an inode. If the name already exists, the file system
@ -337,7 +353,8 @@ type CreateLinkOp struct {
 	//
 	// The lookup count for the inode is implicitly incremented. See notes on
 	// ForgetInodeOp for more information.
-	Entry ChildInodeEntry
+	Entry     ChildInodeEntry
+	OpContext OpContext
 }

 ////////////////////////////////////////////////////////////////////////
@ -388,6 +405,7 @@ type RenameOp struct {
 	// overwritten within it.
 	NewParent InodeID
 	NewName   string
+	OpContext OpContext
 }

 // Unlink a directory from its parent. Because directories cannot have a link
@ -400,8 +418,9 @@ type RenameOp struct {
 type RmDirOp struct {
 	// The ID of parent directory inode, and the name of the directory being
 	// removed within it.
-	Parent InodeID
-	Name   string
+	Parent    InodeID
+	Name      string
+	OpContext OpContext
 }

 // Unlink a file or symlink from its parent. If this brings the inode's link
@ -413,8 +432,9 @@ type RmDirOp struct {
 type UnlinkOp struct {
 	// The ID of parent directory inode, and the name of the entry being removed
 	// within it.
-	Parent InodeID
-	Name   string
+	Parent    InodeID
+	Name      string
+	OpContext OpContext
 }

 ////////////////////////////////////////////////////////////////////////
@ -439,7 +459,8 @@ type OpenDirOp struct {
 	// The handle may be supplied in future ops like ReadDirOp that contain a
 	// directory handle. The file system must ensure this ID remains valid until
 	// a later call to ReleaseDirHandle.
-	Handle HandleID
+	Handle    HandleID
+	OpContext OpContext
 }

 // Read entries from a directory previously opened with OpenDir.
@ -532,6 +553,7 @@ type ReadDirOp struct {
 	// FUSE_DIRENT_ALIGN (http://goo.gl/UziWvH) is less than the read size of
 	// PAGE_SIZE used by fuse_readdir (cf. https://goo.gl/VajtS2).
 	BytesRead int
+	OpContext OpContext
 }

 // Release a previously-minted directory handle. The kernel sends this when
@ -546,7 +568,8 @@ type ReleaseDirHandleOp struct {
 	// The handle ID to be released. The kernel guarantees that this ID will not
 	// be used in further calls to the file system (unless it is reissued by the
 	// file system).
-	Handle HandleID
+	Handle    HandleID
+	OpContext OpContext
 }

 ////////////////////////////////////////////////////////////////////////
@ -596,6 +619,8 @@ type OpenFileOp struct {
 	// layer. This allows for filesystems whose file sizes are not known in
 	// advance, for example, because contents are generated on the fly.
 	UseDirectIO bool
+
+	OpContext OpContext
 }

 // Read data from a file previously opened with CreateFile or OpenFile.
@ -626,6 +651,7 @@ type ReadFileOp struct {
 	//
 	// If direct IO is enabled, semantics should match those of read(2).
 	BytesRead int
+	OpContext OpContext
 }

 // Write data to a file previously opened with CreateFile or OpenFile.
@ -684,7 +710,8 @@ type WriteFileOp struct {
 	// be written, except on error (http://goo.gl/KUpwwn). This appears to be
 	// because it uses file mmapping machinery (http://goo.gl/SGxnaN) to write a
 	// page at a time.
-	Data []byte
+	Data      []byte
+	OpContext OpContext
 }

 // Synchronize the current contents of an open file to storage.
@ -705,8 +732,9 @@ type WriteFileOp struct {
 // file (but which is not used in "real" file systems).
 type SyncFileOp struct {
 	// The file and handle being sync'd.
-	Inode  InodeID
-	Handle HandleID
+	Inode     InodeID
+	Handle    HandleID
+	OpContext OpContext
 }

 // Flush the current state of an open file to storage upon closing a file
@ -761,6 +789,7 @@ type FlushFileOp struct {
 	// The file and handle being flushed.
 	Inode  InodeID
 	Handle HandleID
+	OpContext OpContext
 }

 // Release a previously-minted file handle. The kernel calls this when there
@ -775,7 +804,8 @@ type ReleaseFileHandleOp struct {
 	// The handle ID to be released. The kernel guarantees that this ID will not
 	// be used in further calls to the file system (unless it is reissued by the
 	// file system).
-	Handle HandleID
+	Handle    HandleID
+	OpContext OpContext
 }

 ////////////////////////////////////////////////////////////////////////
@ -788,7 +818,8 @@ type ReadSymlinkOp struct {
 	Inode InodeID

 	// Set by the file system: the target of the symlink.
-	Target string
+	Target    string
+	OpContext OpContext
 }

 ////////////////////////////////////////////////////////////////////////
@ -804,7 +835,8 @@ type RemoveXattrOp struct {
 	Inode InodeID

 	// The name of the extended attribute.
-	Name string
+	Name      string
+	OpContext OpContext
 }

 // Get an extended attribute.
@ -826,6 +858,7 @@ type GetXattrOp struct {
 	// the number of bytes that would have been read into Dst if Dst was
 	// big enough (return ERANGE in this case).
 	BytesRead int
+	OpContext OpContext
 }

 // List all the extended attributes for a file.
@ -846,6 +879,7 @@ type ListXattrOp struct {
 	// the number of bytes that would have been read into Dst if Dst was
 	// big enough (return ERANGE in this case).
 	BytesRead int
+	OpContext OpContext
 }

 // Set an extended attribute.
@ -866,7 +900,8 @@ type SetXattrOp struct {
 	// If Flags is 0x2, and the attribute does not exist, ENOATTR should be returned.
 	// If Flags is 0x0, the extended attribute will be created if need be, or will
 	// simply replace the value if the attribute exists.
-	Flags uint32
+	Flags     uint32
+	OpContext OpContext
 }

 type FallocateOp struct {
@ -885,5 +920,6 @@ type FallocateOp struct {
 	// 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
+	Mode      uint32
+	OpContext OpContext
 }
--- a/samples/in_process.go
+++ b/samples/in_process.go
@ -71,7 +71,7 @@ func (t *SampleTest) SetUp(ti *ogletest.TestInfo) {
 	}
 }

-// Like SetUp, but doens't panic.
+// Like SetUp, but doesn't panic.
 func (t *SampleTest) initialize(
 	ctx context.Context,
 	server fuse.Server,
--- a/samples/memfs/memfs.go
+++ b/samples/memfs/memfs.go
@ -194,6 +194,10 @@ func (fs *memFS) StatFS(
 func (fs *memFS) LookUpInode(
 	ctx context.Context,
 	op *fuseops.LookUpInodeOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -224,6 +228,10 @@ func (fs *memFS) LookUpInode(
 func (fs *memFS) GetInodeAttributes(
 	ctx context.Context,
 	op *fuseops.GetInodeAttributesOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -243,6 +251,10 @@ func (fs *memFS) GetInodeAttributes(
 func (fs *memFS) SetInodeAttributes(
 	ctx context.Context,
 	op *fuseops.SetInodeAttributesOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -272,6 +284,10 @@ func (fs *memFS) SetInodeAttributes(
 func (fs *memFS) MkDir(
 	ctx context.Context,
 	op *fuseops.MkDirOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -314,6 +330,10 @@ func (fs *memFS) MkDir(
 func (fs *memFS) MkNode(
 	ctx context.Context,
 	op *fuseops.MkNodeOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -371,11 +391,15 @@ func (fs *memFS) createFile(

 func (fs *memFS) CreateFile(
 	ctx context.Context,
-	op *fuseops.CreateFileOp) error {
+	op *fuseops.CreateFileOp) (err error) {
+	if op.OpContext.Pid == 0 {
+		// CreateFileOp should have a valid pid in context.
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

-	var err error
 	op.Entry, err = fs.createFile(op.Parent, op.Name, op.Mode)
 	return err
 }
@ -383,6 +407,10 @@ func (fs *memFS) CreateFile(
 func (fs *memFS) CreateSymlink(
 	ctx context.Context,
 	op *fuseops.CreateSymlinkOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -433,6 +461,10 @@ func (fs *memFS) CreateSymlink(
 func (fs *memFS) CreateLink(
 	ctx context.Context,
 	op *fuseops.CreateLinkOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -472,6 +504,10 @@ func (fs *memFS) CreateLink(
 func (fs *memFS) Rename(
 	ctx context.Context,
 	op *fuseops.RenameOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -513,6 +549,10 @@ func (fs *memFS) Rename(
 func (fs *memFS) RmDir(
 	ctx context.Context,
 	op *fuseops.RmDirOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -545,6 +585,10 @@ func (fs *memFS) RmDir(
 func (fs *memFS) Unlink(
 	ctx context.Context,
 	op *fuseops.UnlinkOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -572,6 +616,10 @@ func (fs *memFS) Unlink(
 func (fs *memFS) OpenDir(
 	ctx context.Context,
 	op *fuseops.OpenDirOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -590,6 +638,10 @@ func (fs *memFS) OpenDir(
 func (fs *memFS) ReadDir(
 	ctx context.Context,
 	op *fuseops.ReadDirOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -605,6 +657,11 @@ func (fs *memFS) ReadDir(
 func (fs *memFS) OpenFile(
 	ctx context.Context,
 	op *fuseops.OpenFileOp) error {
+	if op.OpContext.Pid == 0 {
+		// OpenFileOp should have a valid pid in context.
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -623,6 +680,10 @@ func (fs *memFS) OpenFile(
 func (fs *memFS) ReadFile(
 	ctx context.Context,
 	op *fuseops.ReadFileOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -644,6 +705,10 @@ func (fs *memFS) ReadFile(
 func (fs *memFS) WriteFile(
 	ctx context.Context,
 	op *fuseops.WriteFileOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -656,9 +721,23 @@ func (fs *memFS) WriteFile(
 	return err
 }

+func (fs *memFS) FlushFile(
+	ctx context.Context,
+	op *fuseops.FlushFileOp) (err error) {
+	if op.OpContext.Pid == 0 {
+		// FlushFileOp should have a valid pid in context.
+		return fuse.EINVAL
+	}
+	return
+}
+
 func (fs *memFS) ReadSymlink(
 	ctx context.Context,
 	op *fuseops.ReadSymlinkOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -673,6 +752,10 @@ func (fs *memFS) ReadSymlink(

 func (fs *memFS) GetXattr(ctx context.Context,
 	op *fuseops.GetXattrOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -693,6 +776,10 @@ func (fs *memFS) GetXattr(ctx context.Context,

 func (fs *memFS) ListXattr(ctx context.Context,
 	op *fuseops.ListXattrOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()

@ -716,6 +803,10 @@ func (fs *memFS) ListXattr(ctx context.Context,

 func (fs *memFS) RemoveXattr(ctx context.Context,
 	op *fuseops.RemoveXattrOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()
 	inode := fs.getInodeOrDie(op.Inode)
@ -730,6 +821,10 @@ func (fs *memFS) RemoveXattr(ctx context.Context,

 func (fs *memFS) SetXattr(ctx context.Context,
 	op *fuseops.SetXattrOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()
 	inode := fs.getInodeOrDie(op.Inode)
@ -755,6 +850,10 @@ func (fs *memFS) SetXattr(ctx context.Context,

 func (fs *memFS) Fallocate(ctx context.Context,
 	op *fuseops.FallocateOp) error {
+	if op.OpContext.Pid == 0 {
+		return fuse.EINVAL
+	}
+
 	fs.mu.Lock()
 	defer fs.mu.Unlock()
 	inode := fs.getInodeOrDie(op.Inode)
--- a/samples/memfs/memfs_test.go
+++ b/samples/memfs/memfs_test.go
@ -97,6 +97,9 @@ type memFSTest struct {
 }

 func (t *memFSTest) SetUp(ti *TestInfo) {
+	// Disable writeback caching so that pid is always available in OpContext
+	t.MountConfig.DisableWritebackCaching = true
+
 	t.Server = memfs.NewMemFS(currentUid(), currentGid())
 	t.SampleTest.SetUp(ti)
 }