[GIT PULL] overlayfs updates for 6.18

[Amir Goldstein]

Hi Linus,

Please pull overlayfs updates for 6.18.

This branch has been sitting in linux-next for a few weeks,
but I added some RVB last week.

It has gone through the usual overlayfs test routines.

The branch merges cleanly with master branch of the moment.

Note that there is a small change to fs.h in this PR for the
sb encoding helpers.

This change is reviewed by Gabriel and Christian has agreed that I will
merge it through the ovl tree.

Thanks,
Amir.

----------------------------------------------------------------
The following changes since commit 1b237f190eb3d36f52dffe07a40b5eb210280e00:

  Linux 6.17-rc3 (2025-08-24 12:04:12 -0400)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs.git ovl-update-6.18

for you to fetch changes up to ad1423922781e6552f18d055a5742b1cff018cdc:

  ovl: make sure that ovl_create_real() returns a hashed dentry (2025-09-23 12:29:36 +0200)

----------------------------------------------------------------
overlayfs updates for 6.18

- Work by André Almeida to support case-insensitive overlayfs

  Underlying case-insensitive filesystems casefolding is per directory,
  but for overlayfs it is all-or-nothing.  It supports layers where
  all directories are casefolded (with same encoding) or layers where
  no directories are casefolded.

- A fix for a "bug" in Neil's ovl directory lock changes,
  which only manifested itself with casefold enabled layers
  which may return an unhashed negative dentry from lookup.

----------------------------------------------------------------
Amir Goldstein (1):
      ovl: make sure that ovl_create_real() returns a hashed dentry

André Almeida (9):
      fs: Create sb_encoding() helper
      fs: Create sb_same_encoding() helper
      ovl: Prepare for mounting case-insensitive enabled layers
      ovl: Create ovl_casefold() to support casefolded strncmp()
      ovl: Ensure that all layers have the same encoding
      ovl: Set case-insensitive dentry operations for ovl sb
      ovl: Add S_CASEFOLD as part of the inode flag to be copied
      ovl: Check for casefold consistency when creating new dentries
      ovl: Support mounting case-insensitive enabled layers

 fs/overlayfs/copy_up.c   |   2 +-
 fs/overlayfs/dir.c       |  29 ++++++++++-
 fs/overlayfs/inode.c     |   1 +
 fs/overlayfs/namei.c     |  17 ++++---
 fs/overlayfs/overlayfs.h |   8 +--
 fs/overlayfs/ovl_entry.h |   1 +
 fs/overlayfs/params.c    |  15 ++++--
 fs/overlayfs/params.h    |   1 +
 fs/overlayfs/readdir.c   | 126 +++++++++++++++++++++++++++++++++++++++--------
 fs/overlayfs/super.c     |  64 +++++++++++++++++++++++-
 fs/overlayfs/util.c      |   6 +--
 include/linux/fs.h       |  27 +++++++++-
 12 files changed, 254 insertions(+), 43 deletions(-)