kernel-packages team mailing list archive

[Serge Hallyn <1531747@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

If a directory exists in the lowerdir but not in the mounted
overlay, then mkdir of the directory in the target dir results
in a mysterious -EPERM.  I've seen this both in wily kernel
(4.2.0-22-generic #27-Ubuntu) and in a hand-built xenial
master-next (with unrelated patches added).

=====================================================
#!/bin/sh -ex
dir=`mktemp -d`
cleanup() {
	umount -l $dir/t
	rm -rf $dir
}

trap cleanup EXIT

echo "dir is $dir"
mkdir -p $dir/l $dir/u $dir/w $dir/t
mkdir $dir/l/dev
mount -t overlay -o lowerdir=$dir/l,upperdir=$dir/u,workdir=$dir/w o $dir/t
stat $dir/t/dev
rmdir $dir/t/dev
mkdir $dir/t/dev
echo $?
echo "mkdir should have succeeded"
=====================================================

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: Incomplete

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https://bugs.launchpad.net/bugs/1531747

Title:
  overlay: mkdir fails if directory exists in lowerdir

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  If a directory exists in the lowerdir but not in the mounted
  overlay, then mkdir of the directory in the target dir results
  in a mysterious -EPERM.  I've seen this both in wily kernel
  (4.2.0-22-generic #27-Ubuntu) and in a hand-built xenial
  master-next (with unrelated patches added).

  =====================================================
  #!/bin/sh -ex
  dir=`mktemp -d`
  cleanup() {
  	umount -l $dir/t
  	rm -rf $dir
  }

  trap cleanup EXIT

  echo "dir is $dir"
  mkdir -p $dir/l $dir/u $dir/w $dir/t
  mkdir $dir/l/dev
  mount -t overlay -o lowerdir=$dir/l,upperdir=$dir/u,workdir=$dir/w o $dir/t
  stat $dir/t/dev
  rmdir $dir/t/dev
  mkdir $dir/t/dev
  echo $?
  echo "mkdir should have succeeded"
  =====================================================

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