[PATCH 0/6] overlayfs + casefolding

From: Kent Overstreet
Date: Tue May 20 2025 - 01:17:36 EST


This series allows overlayfs and casefolding to safely be used on the
same filesystem by providing exclusion to ensure that overlayfs never
has to deal with casefolded directories.

Currently, overlayfs can't be used _at all_ if a filesystem even
supports casefolding, which is really nasty for users.

Components:

- filesystem has to track, for each directory, "does any _descendent_
have casefolding enabled"

- new inode flag to pass this to VFS layer

- new dcache methods for providing refs for overlayfs, and filesystem
methods for safely clearing this flag

- new superblock flag for indicating to overlayfs & dcache "filesystem
supports casefolding, it's safe to use provided new dcache methods are
used"

Kent Overstreet (6):
bcachefs: BCH_INODE_has_case_insensitive
darray: lift from bcachefs
fs: SB_CASEFOLD
fs: dcache locking for exlusion between overlayfs, casefolding
bcachefs: Hook up d_casefold_enable()
overlayfs: Support casefolded filesystems

MAINTAINERS | 7 +
fs/bcachefs/Makefile | 1 -
fs/bcachefs/bcachefs_format.h | 3 +-
fs/bcachefs/btree_node_scan_types.h | 2 +-
fs/bcachefs/btree_types.h | 2 +-
fs/bcachefs/btree_update.c | 1 +
fs/bcachefs/btree_write_buffer_types.h | 2 +-
fs/bcachefs/disk_accounting_types.h | 2 +-
fs/bcachefs/fs.c | 45 +++++-
fs/bcachefs/fsck.c | 12 +-
fs/bcachefs/inode.c | 8 +-
fs/bcachefs/inode.h | 2 +-
fs/bcachefs/inode_format.h | 7 +-
fs/bcachefs/journal_io.h | 2 +-
fs/bcachefs/journal_sb.c | 2 +-
fs/bcachefs/namei.c | 166 +++++++++++++++++++++-
fs/bcachefs/namei.h | 5 +
fs/bcachefs/rcu_pending.c | 3 +-
fs/bcachefs/sb-downgrade.c | 9 +-
fs/bcachefs/sb-errors_format.h | 4 +-
fs/bcachefs/sb-errors_types.h | 2 +-
fs/bcachefs/sb-members.h | 3 +-
fs/bcachefs/snapshot_types.h | 3 +-
fs/bcachefs/subvolume.h | 1 -
fs/bcachefs/thread_with_file_types.h | 2 +-
fs/bcachefs/util.h | 28 +---
fs/dcache.c | 177 ++++++++++++++++++++++++
fs/libfs.c | 1 +
fs/overlayfs/params.c | 20 ++-
fs/overlayfs/util.c | 19 ++-
{fs/bcachefs => include/linux}/darray.h | 70 +++++-----
include/linux/darray_types.h | 33 +++++
include/linux/dcache.h | 10 ++
include/linux/fs.h | 4 +
lib/Makefile | 2 +-
{fs/bcachefs => lib}/darray.c | 9 +-
36 files changed, 571 insertions(+), 98 deletions(-)
rename {fs/bcachefs => include/linux}/darray.h (64%)
create mode 100644 include/linux/darray_types.h
rename {fs/bcachefs => lib}/darray.c (75%)

--
2.49.0