[PATCH 6.12 020/567] fs/ntfs3: Support timestamps prior to epoch

Greg Kroah-Hartman
2026-01-06T17:15:23Z

From: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

[ Upstream commit 5180138604323895b5c291eca6aa7c20be494ade ]

Before it used an unsigned 64-bit type, which prevented proper handling
of timestamps earlier than 1970-01-01. Switch to a signed 64-bit type to
support pre-epoch timestamps. The issue was caught by xfstests.

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ntfs3/ntfs_fs.h | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/ntfs3/ntfs_fs.h b/fs/ntfs3/ntfs_fs.h
index ff7f241a25b24..a1040060b081f 100644
--- a/fs/ntfs3/ntfs_fs.h
+++ b/fs/ntfs3/ntfs_fs.h
@@ -980,11 +980,12 @@ static inline __le64 kernel2nt(const struct timespec64 *ts)
*/
static inline void nt2kernel(const __le64 tm, struct timespec64 *ts)
{
- u64 t = le64_to_cpu(tm) - _100ns2seconds * SecondsToStartOf1970;
+ s32 t32;
+ /* use signed 64 bit to support timestamps prior to epoch. xfstest 258. */
+ s64 t = le64_to_cpu(tm) - _100ns2seconds * SecondsToStartOf1970;

- // WARNING: do_div changes its first argument(!)
- ts->tv_nsec = do_div(t, _100ns2seconds) * 100;
- ts->tv_sec = t;
+ ts->tv_sec = div_s64_rem(t, _100ns2seconds, &t32);
+ ts->tv_nsec = t32 * 100;
}

static inline struct ntfs_sb_info *ntfs_sb(struct super_block *sb)
--
2.51.0