Linux Kernel Patches Propose New Ptime Timestamp for Content Provenance
A new Linux kernel proposal introduces ptime, a timestamp designed to track a file's original creation date across backups, copies, and filesystem migrations.
A proposed provenance time (ptime) timestamp for Linux, posted in request-for-comments patches on October 28, 2026, records when file contents were originally created and carries that date across backups, copies, and filesystem migrations.
While Linux and several filesystem drivers already track birth time (btime) for inode creation, ptime follows the original creation date of the contents across filesystem boundaries. On a newly created file, ptime matches btime.
The user-settable timestamp allows backup, archive, and filesystem-conversion tools to preserve it whenever mtime is preserved, pairing ctime with btime and mtime with ptime. Two examples illustrate this behavior: a .zsh_history file created in 2019 and a symlink created in 2020 maintain their original dates via ptime when copied to a new home directory on a different filesystem years later, whereas btime records the time of the copy.
The unmerged request-for-comments code enables ptime in the kernel's VFS layer, adds an initial implementation for Btrfs, and includes proof-of-concept Coreutils patches that add ptime support to the stat and cp commands.