remove --remount

greenhouse/diskutil/diskutil.go

@@ -18,58 +18,13 @@ limitations under the License.
 package diskutil
 
 import (
-	"fmt"
-	"os/exec"
-	"strings"
 	"syscall"
 	"time"
 
 	"github.com/djherbis/atime"
 	log "github.com/sirupsen/logrus"
 )
 
-// exec command and returns lines of combined output
-func commandLines(cmd []string) (lines []string, err error) {
-	c := exec.Command(cmd[0], cmd[1:]...)
-	b, err := c.CombinedOutput()
-	if err != nil {
-		return nil, err
-	}
-	return strings.Split(string(b), "\n"), nil
-}
-
-// FindMountForPath wraps `mount` to find the device / mountpoint
-// on which path is mounted
-func FindMountForPath(path string) (device, mountPoint string, err error) {
-	mounts, err := commandLines([]string{"mount"})
-	if err != nil {
-		return "", "", err
-	}
-	// these lines are like:
-	// $fs on $mountpoint type $fs_type ($mountopts)
-	device, mountPoint = "", ""
-	for _, mount := range mounts {
-		parts := strings.Fields(mount)
-		if len(parts) >= 3 {
-			currDevice := parts[0]
-			currMount := parts[2]
-			// we want the longest matching mountpoint
-			if strings.HasPrefix(path, currMount) && len(currMount) > len(mountPoint) {
-				device, mountPoint = currDevice, currMount
-			}
-		}
-	}
-	return device, mountPoint, nil
-}
-
-// Remount `wraps mount -o remount,options device mountPoint`
-func Remount(device, mountPoint, options string) error {
-	_, err := commandLines([]string{
-		"mount", "-o", fmt.Sprintf("remount,%s", options), device, mountPoint,
-	})
-	return err
-}
-
 // GetDiskUsage wraps syscall.Statfs for usage in GCing the disk
 func GetDiskUsage(path string) (percentBlocksFree float64, bytesFree, bytesUsed uint64, err error) {
 	var stat syscall.Statfs_t

greenhouse/gce-storage.yaml

@@ -9,7 +9,10 @@ metadata:
 provisioner: kubernetes.io/gce-pd
 parameters:
   type: pd-ssd
-# so we can get accurat eviction, note that lazytime only works on ext4
+# we want to use a volume with strictatime,lazytime (and not noatime or relatime)
+# so that file access times *are* recorded but are lazily flushed to the disk
+# https://lwn.net/Articles/621046/
+# https://unix.stackexchange.com/questions/276858/why-is-ext4-filesystem-mounted-with-both-relatime-and-lazytime
 mountOptions: ["strictatime", "lazytime"]
 ---
 # 3TB of SSD :-)

greenhouse/main.go

@@ -60,15 +60,6 @@ var evictUntilPercentBlocksFree = flag.Float64("evict-until-percent-blocks-free"
 var diskCheckInterval = flag.Duration("disk-check-interval", time.Second*10,
 	"interval between checking disk usage (and potentially evicting entries)")
 
-// NOTE: remount is a bit of a hack, unfortunately the kubernetes volumes
-// don't really support this and to cleanly track entry access times we
-// want to use a volume with strictatime,lazytime (and not noatime or relatime)
-// so that file access times *are* recorded but are lazily flushed to the disk
-// https://lwn.net/Articles/621046/
-// https://unix.stackexchange.com/questions/276858/why-is-ext4-filesystem-mounted-with-both-relatime-and-lazytime
-var remount = flag.Bool("remount", false,
-	"attempt to remount --dir with strictatime,lazyatime to improve eviction")
-
 // global metrics object, see prometheus.go
 var promMetrics *prometheusMetrics
 
@@ -85,23 +76,6 @@ func main() {
 	if *dir == "" {
 		logrus.Fatal("--dir must be set!")
 	}
-	if *remount {
-		device, mount, err := diskutil.FindMountForPath(*dir)
-		if err != nil {
-			logrus.WithError(err).Errorf("Failed to find mountpoint for %s", *dir)
-		} else {
-			logrus.Warnf(
-				"Attempting to remount %s on %s with 'strictatime,lazyatime'",
-				device, mount,
-			)
-			err = diskutil.Remount(device, mount, "strictatime,lazytime")
-			if err != nil {
-				logrus.WithError(err).Error("Failed to remount with lazyatime!")
-			} else {
-				logrus.Info("Remount complete")
-			}
-		}
-	}
 
 	cache := diskcache.NewCache(*dir)
 	go monitorDiskAndEvict(