whiteout file type? · borgbackup/borg#7174

(2 评论) (0 反应) (0 负责人)Python (10,086 star) (732 fork)batch import

help wantedos: bsdos: macOSquestion

描述

Accidentally stumbled over a file type borg does not support yet: a whiteout (used by overlay fs)

Infos:

"mknod filename w" on macOS
https://www.kernel.org/doc/html/latest/filesystems/overlayfs.html#whiteouts-and-opaque-directories
https://lwn.net/Articles/312641/ there is also some info about white-out
https://www.man7.org/linux/man-pages/man2/rename.2.html
https://docs.python.org/3/library/stat.html#stat.S_ISWHT

Linux: has a hack avoiding a new file type, using a char dev 0:0 for file whiteouts and an xattr for directory whiteouts macOS: has whiteouts FreeBSD: has support for whiteouts, separate file type DT_WHT OpenBSD: no whiteouts NetBSD: ?

Is there a need for backing up / restoring whiteouts?

for a mounted overlay fs, it should be backed up as visible to the user (no whiteouts visible)
can one access the layers individually, so that WHT files would become visible (on BSD)?

贡献者指南

技术栈: python
领域: cli
议题类型: feature
难度: 4
预计时间: 3-5 days
活动状态: stale
清晰度: mostly clear
前置要求: Understanding of overlay filesystemsKnowledge of borg's archive formatFamiliarity with Python file type handling
新手友好度: 25
研究方向: Investigate whether whiteout files need to be preserved in backups and how borg currently handles unknown file types. Review the kernel documentation on overlayfs whiteouts and the Python stat module. Determine the proper way to detect and store whiteout inodes on macOS, FreeBSD, and Linux. Examine borg's codebase for where file types are enumerated and archived.