[PATCH v2 0/5] Overlayfs strict feature requirements

[Amir Goldstein <amir73il@gmail.com>]

Vivek, Miklos,

This series passes overlay/quick xfstests and I verified manually
some expected mount failures with metacopy=on and override with
metacopy=on,strict=off.

Still needs very carefull review and the ovl_check_rename_whiteout()
helper in patch 3 is broken, so I disabled it for now.

Patches 1-3 are marked for stable apply cleanly on v4.19.
Patch 4 doesn't apply to v4.19.
Patch 5 will probably apply, but not sure it is stable material.

I did not change behavior w.r.t enabling of redirect_dir, because
it involves many corner cases and I don't think it matters for stable.
We can always improve it later and let some mount configurations that
used to fail succeed with expected user requested mount options.
When we address the metacopy => redirect_dir dependency, we should also
address the nfs_export => index dependency in a similar manner.

Thanks,
Amir.

Amir Goldstein (5):
  ovl: return error on mount if metacopy cannot be enabled
  ovl: enforce 'strict' feature requirements with metacopy=on
  ovl: enforce 'strict' upper fs requirements with metacopy=on
  ovl: enforce 'strict' unique uuid requirement with metacopy=on
  ovl: enforce 'strict' upper fs and feature requirements with strict=on

 fs/overlayfs/Kconfig     |  23 ++++
 fs/overlayfs/ovl_entry.h |   1 +
 fs/overlayfs/super.c     | 235 ++++++++++++++++++++++++++++++---------
 3 files changed, 208 insertions(+), 51 deletions(-)

-- 
2.17.1