Crumbs, apparently I forgot ever to send this message. :( On Wed, Apr 16, 2025 at 04:43:31PM +0200, Luca Di Maio wrote: > Hi all, > > This is an initial prototype to improve XFS's prototype file > functionality in scenarios where FS reproducibility is important. > > Currently, when populating a filesystem with a prototype file, all generated inodes > receive timestamps set to the creation time rather than preserving timestamps from > their source files. > > This patchset extends the protofile handling to preserve original timestamps (atime, > mtime, ctime) across all inode types. The implementation is split into two parts: > > - First patch extends xfs_protofile.in to track origin path references for directories, > character devices and symlinks, similar to what's already implemented for regular files. > > - Second patch leverages these references to read timestamp metadata from source files > and populate it into the newly created inodes during filesystem creation. > > At the moment, the new `xfs_protofile` generates a file that results > invalid for older `mkfs.xfs` implementations. Also this new implementation > is not compatible with older prototype files. > > I can imagine that new protofiles not working with older `mkfs.xfs` > might not be a problem, but what about backward compatibility? > I didn't find references on prototype file compatibility, is a change > like this unwanted? I think it'd be more ergonomic for mkfs users to introduce an alternate implementation that uses nftw() to copy whole directory trees (like mke2fs -d does) instead of revising a 52-year old file format to support copying attrs of non-regular files. Then we can move people to a mechanism that doesn't require cli options for supporting spaces in filenames and whatnot. --D > If so, what do you think of a versioned support for prototype files? > I was thinking something on the lines of: > > - xfs_protofile > - if the new flag: > - set the first comment accordingly > - add the additional information > - else act as old one > > - proto.c > - check if the doc starts with the comment `:origin-files enabled` > (for example) > - if so, this is the new format > - else old format > > Eager to know your thoughts and ideas > Thanks > L. > > Luca Di Maio (2): > xfs_proto: add origin also for directories, chardevs and symlinks > proto: read origin also for directories, chardevs and symlinks. copy > timestamps from origin. > > mkfs/proto.c | 49 +++++++++++++++++++++++++++++++++++++++++++ > mkfs/xfs_protofile.in | 12 +++++------ > 2 files changed, 55 insertions(+), 6 deletions(-) > > -- > 2.49.0 >
