Re: [PATCH v6 2/4] populate: add ability to populate a filesystem from a directory

[Christoph Hellwig <hch@infradead.org>]

On Thu, Apr 24, 2025 at 03:00:41PM -0700, Darrick J. Wong wrote:
> The thing is, if you were relying on atime/mtime for detection of "file
> data changed since last read" then /not/ copying atime into the
> filesystem breaks that property in the image.

I don't think that matter for images, because no software will keep
running over the upgrade of the image.  Also plenty of people run
with noatime, and btrfs even defaulted to it for a while (not sure if
it still does).

At the same time having the same behavior as mkfs.ext4 is a good thing
by itself because people obviously have been using it and consistency
is always a good thing.

> How about copying [acm]time from the source file by default, but then
> add a new -p noatime option to skip the atime?

I'd probably invert the polarity.  When building an image keeping
atime especially and also ctime is usually not very useful.  But that
would give folks who need it for some reason a way to do so.