| From: |
| Artem Blagodarenko <artem.blagodarenko-AT-gmail.com> |
| To: |
| linux-ext4-AT-vger.kernel.org |
| Subject: |
| [PATCH v2 00/10] Data in direntry (dirdata) feature |
| Date: |
| Wed, 10 Jun 2026 11:24:03 -0400 |
| Message-ID: |
| <20260610152417.13576-1-ablagodarenko@thelustrecollective.com> |
| Cc: |
| adilger.kernel-AT-dilger.ca, Artem Blagodarenko <ablagodarenko-AT-thelustrecollective.com>, Andreas Dilger <adilger-AT-dilger.ca>, syzbot-AT-syzkaller.appspotmail.com |
| Archive-link: |
| Article |
EXT4 currently stores a hash in the directory entry
(dirent) immediately after the file name to support
simultaneous fscrypt and casefold functionality.
It has been discussed within the EXT4 community that
this hash could instead be stored in dirdata. This
would make it the second (or third, in the case of
64-bit inode counts) user of dirdata.
At the same time, the existing format—where the hash
is placed after the file name—must continue to be
supported. With these patches, EXT4 can handle the
hash in both formats.
The first user of this feature is LUFID -
Locally Unique File ID.
Support for fscrypt and case-insensitive directories
with dirdata enabled has been verified using a
dedicated xfstest submitted to the xfstests list as
a separate patch.
e2fsprogs support is provided in a separate patches
series.
Changes in v2:
- Split the patch set into 10 smaller patchesfor
easier reading and review.
- Added an IOCTL to set the LUFID for testing purposes.
LUFIDs can be listed via debugfs. Corresponding support
has been added in the related e2fsprogs series.
- Removed the dirdata mount option.
- Fixed the following issue:
KASAN: slab-out-of-bounds read in __ext4_check_dir_entry
- Rebased onto the latest codebase.
Artem Blagodarenko (10):
ext4: replace ext4_dir_entry with ext4_dir_entry_2
ext4: add ext4_dir_entry_is_tail()
ext4: refactor dx_root to support variable dirent sizes
ext4: add dirdata format definitions and access helpers
ext4: preserve dirdata bits in get_dtype()
ext4: add ext4_dir_entry_len() and harden dirdata parsing
ext4: rename ext4_dir_rec_len() and clarify dirdata usage
ext4: dirdata feature
ext4: add dirdata set/get helpers
ext4: Add EXT4_IOC_SET_LUFID ioctl for setting LUFID on directory
entries
foofile.txt | 0
fs/ext4/dir.c | 9 +-
fs/ext4/ext4.h | 205 ++++++++++++-
fs/ext4/inline.c | 37 ++-
fs/ext4/ioctl.c | 62 ++++
fs/ext4/namei.c | 587 +++++++++++++++++++++++++++-----------
fs/ext4/sysfs.c | 2 +
include/uapi/linux/ext4.h | 13 +
8 files changed, 723 insertions(+), 192 deletions(-)
create mode 100644 foofile.txt
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Tested-by: syzbot@syzkaller.appspotmail.com
--
2.43.7
