Re: [PATCH 1/2] xfs_db rdump: remove sole_path logic

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Nov 12, 2025 at 10:45:37PM +0300, Alexander Monakov wrote:
> 
> On Wed, 12 Nov 2025, Darrick J. Wong wrote:
> 
> > On Wed, Nov 12, 2025 at 06:19:31PM +0300, Alexander Monakov wrote:
> > > Eliminate special handling of the case where rdump'ing one directory
> > > does not create the corresponding directory in the destination, but
> > > instead modifies the destination's attributes and creates children
> > > alongside the pre-existing children.
> > 
> > It sounds like what happened is that you ran rdump with a non-empty
> > destdir, only to have rdump mutate the existing children in that
> > directory.  Is that correct?
> 
> Not really (what you describe would have been even worse).
> 
> In my case, I was rdump'ing into a directory that had rtinherit set, and
> rdump undid that (generally speaking, all attributes of the destdir were
> overwritten, not just rtinherit).
> 
> > If so, then I think what you really wanted was for rdump to check for
> > that and error out, unless explicit --overwrite permission had been
> > granted.  Because...
> 
> (I would still hit the above issue with attributes)
> 
> > > This can be a trap for the unwary (the effect on attributes can be
> > > particularly surprising and non-trivial to undo), and, in general, fewer
> > > special cases in such a low-level tool should be desirable.
> > 
> > ...I use this "special case" and don't understand why you decided that
> > removing functionality was the solution here.  This is a filesystem
> > debugger, there are weird functions and sharp edges everywhere.
> 
> Shouldn't we strive to have fewer surprises? For instance, if there was
> an explicit flag for that, there wouldn't be an issue.
> 
> Out of curiosity, what is your use-case for this?

Copying build artifacts out of a directory on an xfs filesystem into
some other directory, e.g.

# xfs_db -c 'rdump /rootfs /srv/containers/whatever' /dev/sda1

Without then having to do:

# mv /srv/containers/whatever/rootfs/* /srv/containers/whatever/
# rmdir /srv/containers/whatever/rootfs

I'd be willing to accept more rsync-like behavior where a trailing slash
means "copy children directly into the target dir" and no trailing slash
means "create new child subdir in target dir and copy stuff into that".

IOWs,

xfs_db> rdump /rootfs /srv/containers/whatever

Would always create /srv/containers/whatever/rootfs and copy the
children of /rootfs into that path, but

xfs_db> rdump /rootfs/ /srv/containers/whatever/boot

Would copy the children of /rootfs directly into
/srv/containers/whatever/boot.

--D


> Thank you.
> Alexander
>