Refactor FUSE connection for readability and structure

This change decouples the code that is weakly
tied to the connection struct from connection.go,
rename variables and files with more meaningful choices,
adds detailed comments, explains lock orders,
and adds other minor improvement to make
the existing FUSE code more readable and
more organized.

Purpose is to avoid too much code in one file
and provide better structure for the
future commits.

1 files changed, 15 insertions, 10 deletions

diff --git a/pkg/sentry/fsimpl/fuse/fusefs.go b/pkg/sentry/fsimpl/fuse/fusefs.go
index 572245303..30725182a 100644
--- a/pkg/sentry/fsimpl/fuse/fusefs.go
+++ b/pkg/sentry/fsimpl/fuse/fusefs.go
@@ -35,6 +35,10 @@ import (
 // Name is the default filesystem name.
 const Name = "fuse"
 
+// maxActiveRequestsDefault is the default setting controlling the upper bound
+// on the number of active requests at any given time.
+const maxActiveRequestsDefault = 10000
+
 // FilesystemType implements vfs.FilesystemType.
 type FilesystemType struct{}
 
@@ -168,12 +172,12 @@ func (fsType FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
 
 	// Check for unparsed options.
 	if len(mopts) != 0 {
-		log.Warningf("%s.GetFilesystem: unknown options: %v", fsType.Name(), mopts)
+		log.Warningf("%s.GetFilesystem: unsupported or unknown options: %v", fsType.Name(), mopts)
 		return nil, nil, syserror.EINVAL
 	}
 
 	// Create a new FUSE filesystem.
-	fs, err := NewFUSEFilesystem(ctx, devMinor, &fsopts, fuseFd)
+	fs, err := newFUSEFilesystem(ctx, devMinor, &fsopts, fuseFd)
 	if err != nil {
 		log.Warningf("%s.NewFUSEFilesystem: failed with error: %v", fsType.Name(), err)
 		return nil, nil, err
@@ -194,21 +198,22 @@ func (fsType FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
 	return fs.VFSFilesystem(), root.VFSDentry(), nil
 }
 
-// NewFUSEFilesystem creates a new FUSE filesystem.
-func NewFUSEFilesystem(ctx context.Context, devMinor uint32, opts *filesystemOptions, device *vfs.FileDescription) (*filesystem, error) {
-	fs := &filesystem{
-		devMinor: devMinor,
-		opts:     opts,
-	}
-
+// newFUSEFilesystem creates a new FUSE filesystem.
+func newFUSEFilesystem(ctx context.Context, devMinor uint32, opts *filesystemOptions, device *vfs.FileDescription) (*filesystem, error) {
 	conn, err := newFUSEConnection(ctx, device, opts)
 	if err != nil {
 		log.Warningf("fuse.NewFUSEFilesystem: NewFUSEConnection failed with error: %v", err)
 		return nil, syserror.EINVAL
 	}
 
-	fs.conn = conn
 	fuseFD := device.Impl().(*DeviceFD)
+
+	fs := &filesystem{
+		devMinor: devMinor,
+		opts:     opts,
+		conn:     conn,
+	}
+
 	fuseFD.fs = fs
 
 	return fs, nil