cephfs: detect corrupt ceph-fuse mounts and try to remount

Mounts managed by ceph-fuse may get corrupted by e.g. the ceph-fuse process
exiting abruptly, or its parent container being terminated, taking down its
child processes with it.

This commit adds checks to NodeStageVolume and NodePublishVolume procedures
to detect whether a mountpoint in staging_target_path and/or target_path is
corrupted, and remount is performed if corruption is detected.

Signed-off-by: Robert Vasek <robert.vasek@cern.ch>

internal/util/util.go

@@ -308,6 +308,18 @@ func IsMountPoint(p string) (bool, error) {
 	return !notMnt, nil
 }
 
+// IsCorruptedMountError checks if the given error is a result of a corrupted
+// mountpoint.
+func IsCorruptedMountError(err error) bool {
+	return mount.IsCorruptedMnt(err)
+}
+
+// ReadMountInfoForProc reads /proc/<PID>/mountpoint and marshals it into
+// MountInfo structs.
+func ReadMountInfoForProc(proc string) ([]mount.MountInfo, error) {
+	return mount.ParseMountInfo(fmt.Sprintf("/proc/%s/mountinfo", proc))
+}
+
 // Mount mounts the source to target path.
 func Mount(source, target, fstype string, options []string) error {
 	dummyMount := mount.New("")