Add FilesystemType.Name method, and FilesystemType field to Filesystem struct.

Both have analogues in Linux:
* struct file_system_type has a char *name field.
* struct super_block keeps a pointer to the file_system_type.

These fields are necessary to support the `filesystem type` field in
/proc/[pid]/mountinfo.

PiperOrigin-RevId: 303434063

1 files changed, 10 insertions, 1 deletions

diff --git a/pkg/sentry/vfs/filesystem.go b/pkg/sentry/vfs/filesystem.go
index 7b7d233f9..cd34782ff 100644
--- a/pkg/sentry/vfs/filesystem.go
+++ b/pkg/sentry/vfs/filesystem.go
@@ -42,21 +42,30 @@ type Filesystem struct {
 	// immutable.
 	vfs *VirtualFilesystem
 
+	// fsType is the FilesystemType of this Filesystem.
+	fsType FilesystemType
+
 	// impl is the FilesystemImpl associated with this Filesystem. impl is
 	// immutable. This should be the last field in Dentry.
 	impl FilesystemImpl
 }
 
 // Init must be called before first use of fs.
-func (fs *Filesystem) Init(vfsObj *VirtualFilesystem, impl FilesystemImpl) {
+func (fs *Filesystem) Init(vfsObj *VirtualFilesystem, fsType FilesystemType, impl FilesystemImpl) {
 	fs.refs = 1
 	fs.vfs = vfsObj
+	fs.fsType = fsType
 	fs.impl = impl
 	vfsObj.filesystemsMu.Lock()
 	vfsObj.filesystems[fs] = struct{}{}
 	vfsObj.filesystemsMu.Unlock()
 }
 
+// FilesystemType returns the FilesystemType for this Filesystem.
+func (fs *Filesystem) FilesystemType() FilesystemType {
+	return fs.fsType
+}
+
 // VirtualFilesystem returns the containing VirtualFilesystem.
 func (fs *Filesystem) VirtualFilesystem() *VirtualFilesystem {
 	return fs.vfs