Comment 14 for bug 1824407

Comparing the previous debug with 2 squashfs overlayfs lowers with the *same* data on ext4 as the 2 overlayfs lowers we have:

[ 56.257691] repro-nosquashf (1038): drop_caches: 3
[ 56.265075] ovl_get_fh: 112 dentry: etc/.pwd.lock name: trusted.overlay.origin
[ 56.265077] ovl_get_fh: 115: res = 29
[ 56.265079] ovl_get_fh: 152: return fh = 00000000b56cf4e7
[ 56.265079] ovl_check_origin: 413 fh = 00000000b56cf4e7
[ 56.265080] ovl_check_origin_fh: 354 upperdentry = etc/.pwd.lock
[ 56.265081] ovl_decode_real_fh: 174
[ 56.265081] ovl_decode_real_fh: 181 uuid not equal, return NULL
[ 56.265082] ovl_check_origin_fh: 363, i=0, origin = NULL
[ 56.265082] ovl_decode_real_fh: 174
[ 56.266162] ovl_decode_real_fh: 211 return dentry (OK)
[ 56.266163] ovl_check_origin_fh: 360, i=1, origin = /
[ 56.266164] ovl_check_origin_fh: level=1 upper: etc/.pwd.lock 100600, lower: / 100600
[ 56.266166] ovl_check_origin_fh: 395 return 0
[ 56.266166] ovl_check_origin: 422 err = 0
[ 56.266167] ovl_check_origin: 439, return 0
  (
So this works fine, note that the squashfs lower / is 40755 (S_IFDIR | S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH) where as the ext3 lower / is 100600 (S_IFREG | S_IRUSR | S_IWUSR)