Reverted changes to memfs.

statfs(2) is more involved than I expected, so this calls for its own
sample file system to test in a more focused manner.

samples/memfs/memfs.go

@@ -28,12 +28,6 @@ import (
 	"github.com/jacobsa/syncutil"
 )
 
-// The capacities of the file system, as reported to statfs(2).
-const (
-	Capacity_Bytes = 1 << 50
-	Capacity_Files = 1 << 30
-)
-
 type memFS struct {
 	fuseutil.NotImplementedFileSystem
 
@@ -190,34 +184,6 @@ func (fs *memFS) deallocateInode(id fuseops.InodeID) {
 // FileSystem methods
 ////////////////////////////////////////////////////////////////////////
 
-func (fs *memFS) StatFS(
-	ctx context.Context,
-	op *fuseops.StatFSOp) (err error) {
-	fs.mu.Lock()
-	defer fs.mu.Unlock()
-
-	// Count free/available bytes and inodes.
-	op.BlockSize = 1
-	op.Blocks = Capacity_Bytes
-	op.BlocksFree = Capacity_Bytes
-	op.BlocksAvailable = Capacity_Bytes
-
-	op.Inodes = Capacity_Files
-	op.InodesFree = Capacity_Files
-
-	for _, in := range fs.inodes {
-		if in == nil {
-			continue
-		}
-
-		op.InodesFree--
-		op.BlocksFree -= in.attrs.Size
-		op.BlocksAvailable -= in.attrs.Size
-	}
-
-	return
-}
-
 func (fs *memFS) LookUpInode(
 	ctx context.Context,
 	op *fuseops.LookUpInodeOp) (err error) {

samples/memfs/memfs_test.go

@@ -1614,27 +1614,3 @@ func (t *MemFSTest) RenameNonExistentFile() {
 	err = os.Rename(path.Join(t.Dir, "foo"), path.Join(t.Dir, "bar"))
 	ExpectThat(err, Error(HasSubstr("no such file")))
 }
-
-func (t *MemFSTest) Statfs() {
-	var err error
-	var stat syscall.Statfs_t
-
-	// Write a few bytes of file content.
-	const content = "taco"
-
-	err = ioutil.WriteFile(path.Join(t.Dir, "foo"), []byte(content), 0400)
-	AssertEq(nil, err)
-
-	// Stat the file system.
-	err = syscall.Statfs(t.Dir, &stat)
-	AssertEq(nil, err)
-
-	ExpectEq(1, stat.Bsize)
-
-	ExpectEq(memfs.Capacity_Bytes, stat.Blocks)
-	ExpectEq(memfs.Capacity_Bytes-len(content), stat.Bfree)
-	ExpectEq(stat.Bfree, stat.Bavail)
-
-	ExpectEq(memfs.Capacity_Files, stat.Files)
-	ExpectEq(memfs.Capacity_Files-2, stat.Ffree)
-}