Set the FilesytemType in MountSource from the Filesystem.

And stop storing the Filesystem in the MountSource.

This allows us to decouple the MountSource filesystem type from the name of the
filesystem.

PiperOrigin-RevId: 247292982
Change-Id: I49cbcce3c17883b7aa918ba76203dfd6d1b03cc8

pkg/sentry/fs/mount.go

@@ -110,9 +110,8 @@ type MountSource struct {
 	// MountSourceOperations defines filesystem specific behavior.
 	MountSourceOperations
 
-	// Filesystem is the filesystem backing the mount. Can be nil if there
-	// is no filesystem backing the mount.
-	Filesystem Filesystem
+	// FilesystemType is the type of the filesystem backing this mount.
+	FilesystemType string
 
 	// Flags are the flags that this filesystem was mounted with.
 	Flags MountSourceFlags
@@ -158,10 +157,14 @@ const DefaultDirentCacheSize uint64 = 1000
 // NewMountSource returns a new MountSource. Filesystem may be nil if there is no
 // filesystem backing the mount.
 func NewMountSource(mops MountSourceOperations, filesystem Filesystem, flags MountSourceFlags) *MountSource {
+	fsType := "none"
+	if filesystem != nil {
+		fsType = filesystem.Name()
+	}
 	return &MountSource{
 		MountSourceOperations: mops,
 		Flags:                 flags,
-		Filesystem:            filesystem,
+		FilesystemType:        fsType,
 		fscache:               NewDirentCache(DefaultDirentCacheSize),
 		children:              make(map[*MountSource]struct{}),
 	}

pkg/sentry/fs/proc/mounts.go

@@ -139,11 +139,7 @@ func (mif *mountInfoFile) ReadSeqFileData(ctx context.Context, handle seqfile.Se
 		fmt.Fprintf(&buf, "- ")
 
 		// (9) Filesystem type.
-		name := "none"
-		if m.Filesystem != nil {
-			name = m.Filesystem.Name()
-		}
-		fmt.Fprintf(&buf, "%s ", name)
+		fmt.Fprintf(&buf, "%s ", m.FilesystemType)
 
 		// (10) Mount source: filesystem-specific information or "none".
 		fmt.Fprintf(&buf, "none ")
@@ -190,11 +186,7 @@ func (mf *mountsFile) ReadSeqFileData(ctx context.Context, handle seqfile.SeqHan
 		if m.Flags.ReadOnly {
 			opts = "ro"
 		}
-		name := "none"
-		if m.Filesystem != nil {
-			name = m.Filesystem.Name()
-		}
-		fmt.Fprintf(&buf, "%s %s %s %s %d %d\n", "none", mountPath, name, opts, 0, 0)
+		fmt.Fprintf(&buf, "%s %s %s %s %d %d\n", "none", mountPath, m.FilesystemType, opts, 0, 0)
 	})
 
 	return []seqfile.SeqData{{Buf: buf.Bytes(), Handle: (*mountsFile)(nil)}}, 0

pkg/tcpip/link/muxed/BUILD

@@ -1,6 +1,8 @@
 load("//tools/go_stateify:defs.bzl", "go_library", "go_test")
 
-package(licenses = ["notice"])  # Apache 2.0
+package(
+    licenses = ["notice"],  # Apache 2.0
+)
 
 go_library(
     name = "muxed",

pkg/tcpip/transport/raw/BUILD

@@ -1,4 +1,6 @@
-package(licenses = ["notice"])  # Apache 2.0
+package(
+    licenses = ["notice"],  # Apache 2.0
+)
 
 load("//tools/go_generics:defs.bzl", "go_template_instance")
 load("//tools/go_stateify:defs.bzl", "go_library")

runsc/BUILD

@@ -1,4 +1,6 @@
-package(licenses = ["notice"])  # Apache 2.0
+package(
+    licenses = ["notice"],  # Apache 2.0
+)
 
 load("@io_bazel_rules_go//go:def.bzl", "go_binary")
 load("@bazel_tools//tools/build_defs/pkg:pkg.bzl", "pkg_deb", "pkg_tar")