This series adds Kunit tests for fs/ext4/hash.c and refactors
the str2hashbuf_{signed,unsigned}() helpers.

Patch 1 adds test coverage for ext4fs_dirhash(), including the main
hash variants and relevant edge cases.

Patch 2 simplifies the str2hashbuf helper implementation by processing
input in 4-byte chunks and removing function-pointer dispatch. This also
reduces overhead and shows roughly 2x improvement on longer inputs in
local testing.

Thanks,
Guan-Chun Wu

Link: https://lore.kernel.org/lkml/20260529200308.889706-1-409411716@gms.tku.edu.tw/

---

v4 -> v5 :

  - Fix NULL pointer dereference and out-of-bounds read in SipHash tests.
  - Use IS_ERR() instead of NULL check for utf8_load() error handling.
  - Fix unicode_map memory leaks on assertion failures via kunit_add_action_or_reset().
  - Avoid a UBSAN shift warning in str2hashbuf by casting signed char values
    to __u32 before left-shifting them.

---

Guan-Chun Wu (2):
  ext4: add Kunit coverage for directory hash computation
  ext4: improve str2hashbuf by processing 4-byte chunks and removing
    function pointers

 fs/ext4/Makefile    |   2 +-
 fs/ext4/hash-test.c | 560 ++++++++++++++++++++++++++++++++++++++++++++
 fs/ext4/hash.c      |  68 ++++--
 3 files changed, 607 insertions(+), 23 deletions(-)
 create mode 100644 fs/ext4/hash-test.c

-- 
2.34.1