6 files changed, 25 insertions, 15 deletions
diff --git a/pkg/sentry/vfs/BUILD b/pkg/sentry/vfs/BUILD
index df4990854..ac60fe8bf 100644
--- a/pkg/sentry/vfs/BUILD
+++ b/pkg/sentry/vfs/BUILD
@@ -99,6 +99,7 @@ go_library(
         "//pkg/fdnotifier",
         "//pkg/fspath",
         "//pkg/gohacks",
+        "//pkg/hostarch",
         "//pkg/log",
         "//pkg/refs",
         "//pkg/refsvfs2",
diff --git a/pkg/sentry/vfs/anonfs.go b/pkg/sentry/vfs/anonfs.go
index 3caf417ca..f48817132 100644
--- a/pkg/sentry/vfs/anonfs.go
+++ b/pkg/sentry/vfs/anonfs.go
@@ -20,10 +20,10 @@ import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/fspath"
+	"gvisor.dev/gvisor/pkg/hostarch"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/socket/unix/transport"
 	"gvisor.dev/gvisor/pkg/syserror"
-	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // NewAnonVirtualDentry returns a VirtualDentry with the given synthetic name,
@@ -43,7 +43,7 @@ func (vfs *VirtualFilesystem) NewAnonVirtualDentry(name string) VirtualDentry {
 }
 
 const (
-	anonfsBlockSize = usermem.PageSize // via fs/libfs.c:pseudo_fs_fill_super()
+	anonfsBlockSize = hostarch.PageSize // via fs/libfs.c:pseudo_fs_fill_super()
 
 	// Mode, UID, and GID for a generic anonfs file.
 	anonFileMode = 0600 // no type is correct
diff --git a/pkg/sentry/vfs/file_description_impl_util.go b/pkg/sentry/vfs/file_description_impl_util.go
index 1556b41a3..b87d9690a 100644
--- a/pkg/sentry/vfs/file_description_impl_util.go
+++ b/pkg/sentry/vfs/file_description_impl_util.go
@@ -252,6 +252,9 @@ type WritableDynamicBytesSource interface {
 // are backed by a bytes.Buffer that is regenerated when necessary, consistent
 // with Linux's fs/seq_file.c:single_open().
 //
+// If data additionally implements WritableDynamicBytesSource, writes are
+// dispatched to the implementer. The source data is not automatically modified.
+//
 // DynamicBytesFileDescriptionImpl.SetDataSource() must be called before first
 // use.
 //
diff --git a/pkg/sentry/vfs/filesystem_impl_util.go b/pkg/sentry/vfs/filesystem_impl_util.go
index 2620cf975..15b234d61 100644
--- a/pkg/sentry/vfs/filesystem_impl_util.go
+++ b/pkg/sentry/vfs/filesystem_impl_util.go
@@ -18,7 +18,7 @@ import (
 	"strings"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/usermem"
+	"gvisor.dev/gvisor/pkg/hostarch"
 )
 
 // GenericParseMountOptions parses a comma-separated list of options of the
@@ -50,7 +50,7 @@ func GenericParseMountOptions(str string) map[string]string {
 func GenericStatFS(fsMagic uint64) linux.Statfs {
 	return linux.Statfs{
 		Type:       fsMagic,
-		BlockSize:  usermem.PageSize,
+		BlockSize:  hostarch.PageSize,
 		NameLength: linux.NAME_MAX,
 	}
 }
diff --git a/pkg/sentry/vfs/inotify.go b/pkg/sentry/vfs/inotify.go
index 32fa01578..49d29e20b 100644
--- a/pkg/sentry/vfs/inotify.go
+++ b/pkg/sentry/vfs/inotify.go
@@ -21,6 +21,7 @@ import (
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/hostarch"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/uniqueid"
 	"gvisor.dev/gvisor/pkg/sync"
@@ -256,7 +257,7 @@ func (i *Inotify) Ioctl(ctx context.Context, uio usermem.IO, args arch.SyscallAr
 			n += uint32(e.sizeOf())
 		}
 		var buf [4]byte
-		usermem.ByteOrder.PutUint32(buf[:], n)
+		hostarch.ByteOrder.PutUint32(buf[:], n)
 		_, err := uio.CopyOut(ctx, args[2].Pointer(), buf[:], usermem.IOOpts{})
 		return 0, err
 
@@ -683,10 +684,10 @@ func (e *Event) sizeOf() int {
 // construct the output. We use a buffer allocated ahead of time for
 // performance. buf must be at least inotifyEventBaseSize bytes.
 func (e *Event) CopyTo(ctx context.Context, buf []byte, dst usermem.IOSequence) (int64, error) {
-	usermem.ByteOrder.PutUint32(buf[0:], uint32(e.wd))
-	usermem.ByteOrder.PutUint32(buf[4:], e.mask)
-	usermem.ByteOrder.PutUint32(buf[8:], e.cookie)
-	usermem.ByteOrder.PutUint32(buf[12:], e.len)
+	hostarch.ByteOrder.PutUint32(buf[0:], uint32(e.wd))
+	hostarch.ByteOrder.PutUint32(buf[4:], e.mask)
+	hostarch.ByteOrder.PutUint32(buf[8:], e.cookie)
+	hostarch.ByteOrder.PutUint32(buf[12:], e.len)
 
 	writeLen := 0
 
diff --git a/pkg/sentry/vfs/mount.go b/pkg/sentry/vfs/mount.go
index 922f9e697..7cdab6945 100644
--- a/pkg/sentry/vfs/mount.go
+++ b/pkg/sentry/vfs/mount.go
@@ -970,17 +970,22 @@ func superBlockOpts(mountPath string, mnt *Mount) string {
 		opts += "," + mopts
 	}
 
-	// NOTE(b/147673608): If the mount is a cgroup, we also need to include
-	// the cgroup name in the options. For now we just read that from the
-	// path.
+	// NOTE(b/147673608): If the mount is a ramdisk-based fake cgroupfs, we also
+	// need to include the cgroup name in the options. For now we just read that
+	// from the path. Note that this is only possible when "cgroup" isn't
+	// registered as a valid filesystem type.
 	//
-	// TODO(gvisor.dev/issue/190): Once gVisor has full cgroup support, we
-	// should get this value from the cgroup itself, and not rely on the
-	// path.
+	// TODO(gvisor.dev/issue/190): Once we removed fake cgroupfs support, we
+	// should remove this.
+	if cgroupfs := mnt.vfs.getFilesystemType("cgroup"); cgroupfs != nil && cgroupfs.opts.AllowUserMount {
+		// Real cgroupfs available.
+		return opts
+	}
 	if mnt.fs.FilesystemType().Name() == "cgroup" {
 		splitPath := strings.Split(mountPath, "/")
 		cgroupType := splitPath[len(splitPath)-1]
 		opts += "," + cgroupType
 	}
+
 	return opts
 }