From 54ad710d241f6e6d48859cfefbd7c407bad89ef6 Mon Sep 17 00:00:00 2001
From: Vitaliy Filippov <vitalif@yourcmc.ru>
Date: Wed, 22 Mar 2023 18:46:22 +0300
Subject: [PATCH] Add PollOp

---
 conversions.go                          | 20 ++++++++++++++++++++
 fuseops/ops.go                          | 25 +++++++++++++++++++++++++
 fuseutil/file_system.go                 |  4 ++++
 fuseutil/not_implemented_file_system.go |  6 ++++++
 4 files changed, 55 insertions(+)

diff --git a/conversions.go b/conversions.go
index ac512c1..b0c25d5 100644
--- a/conversions.go
+++ b/conversions.go
@@ -688,6 +688,22 @@ func convertInMessage(
 				Pid:    inMsg.Header().Pid},
 		}
 
+	case fusekernel.OpPoll:
+		type input fusekernel.PollIn
+		in := (*input)(inMsg.Consume(unsafe.Sizeof(input{})))
+		if in == nil {
+			return nil, errors.New("Corrupt OpPoll")
+		}
+
+		o = &fuseops.PollOp{
+			Inode:     fuseops.InodeID(inMsg.Header().Nodeid),
+			Handle:    fuseops.HandleID(in.Fh),
+			Kh:        in.Kh,
+			Flags:     fusekernel.PollFlags(in.Flags),
+			Events:    fusekernel.PollEvents(in.Events),
+			OpContext: fuseops.OpContext{Pid: inMsg.Header().Pid},
+		}
+
 	default:
 		o = &unknownOp{
 			OpCode: inMsg.Header().Opcode,
@@ -944,6 +960,10 @@ func (c *Connection) kernelResponseForOp(
 		out.TimeGran = 1
 		out.MaxPages = o.MaxPages
 
+	case *fuseops.PollOp:
+		out := (*fusekernel.PollOut)(m.Grow(int(unsafe.Sizeof(fusekernel.PollOut{}))))
+		out.Revents = uint32(o.Revents)
+
 	default:
 		panic(fmt.Sprintf("Unexpected op: %#v", op))
 	}
diff --git a/fuseops/ops.go b/fuseops/ops.go
index 7e1a143..9001b74 100644
--- a/fuseops/ops.go
+++ b/fuseops/ops.go
@@ -965,3 +965,28 @@ type FallocateOp struct {
 	Mode      uint32
 	OpContext OpContext
 }
+
+// Request notifications when the file system user calls poll/select or
+// similar operations on a file.
+type PollOp struct {
+	// The inode and handle the user wants to poll
+	Inode  InodeID
+	Handle HandleID
+
+	// Kh is the "kernel handle". The reason behind it is that it's allocated
+	// by the kernel on file allocation and guaranteed to be unique as opposed
+	// to regular file handles (HandleID) generated by the userland server
+	// (by us). Kh has to be used in NotifyPollWakeupOut replies.
+	Kh uint64
+
+	// Poll flags
+	Flags fusekernel.PollFlags
+
+	// Requested events
+	Events fusekernel.PollEvents
+
+	// Set by the file system: the actual events that have happened
+	// since the last poll
+	Revents   fusekernel.PollEvents
+	OpContext OpContext
+}
diff --git a/fuseutil/file_system.go b/fuseutil/file_system.go
index 5eab68a..bef2145 100644
--- a/fuseutil/file_system.go
+++ b/fuseutil/file_system.go
@@ -63,6 +63,7 @@ type FileSystem interface {
 	ListXattr(context.Context, *fuseops.ListXattrOp) error
 	SetXattr(context.Context, *fuseops.SetXattrOp) error
 	Fallocate(context.Context, *fuseops.FallocateOp) error
+	Poll(context.Context, *fuseops.PollOp) error
 
 	// Regard all inodes (including the root inode) as having their lookup counts
 	// decremented to zero, and clean up any resources associated with the file
@@ -236,6 +237,9 @@ func (s *fileSystemServer) handleOp(
 
 	case *fuseops.FallocateOp:
 		err = s.fs.Fallocate(ctx, typed)
+
+	case *fuseops.PollOp:
+		err = s.fs.Poll(ctx, typed)
 	}
 
 	c.Reply(ctx, err)
diff --git a/fuseutil/not_implemented_file_system.go b/fuseutil/not_implemented_file_system.go
index cfb116c..356327e 100644
--- a/fuseutil/not_implemented_file_system.go
+++ b/fuseutil/not_implemented_file_system.go
@@ -204,5 +204,11 @@ func (fs *NotImplementedFileSystem) Fallocate(
 	return fuse.ENOSYS
 }
 
+func (fs *NotImplementedFileSystem) Poll(
+	ctx context.Context,
+	op *fuseops.PollOp) error {
+	return fuse.ENOSYS
+}
+
 func (fs *NotImplementedFileSystem) Destroy() {
 }