Re: [PATCH 1/6] xfs: don't move nondir/nonreg temporary repair files to the metadir namespace

[Christoph Hellwig <hch@infradead.org>]

On Wed, Dec 04, 2024 at 10:14:50PM -0800, Darrick J. Wong wrote:
> The function opportunistically moves sc->tempip from the regular
> directory tree to the metadata directory tree if sc->ip is part of the
> metadata directory tree.  However, the scrub setup functions grab sc->ip
> and create sc->tempip before we actually get around to checking if the
> file is the right type for the scrubber.
> 
> IOWs, you can invoke the symlink scrubber with the file handle of a
> subdirectory in the metadir.  xrep_setup_symlink will create a temporary
> symlink file, xrep_tempfile_adjust_directory_tree will foolishly try to
> set the METADATA flag on the temp symlink, which trips the inode
> verifier in the inode item precommit, which shuts down the filesystem
> when expensive checks are turned on.  If they're /not/ turned on, then
> xchk_symlink will return ENOENT when it sees that it's been passed a
> symlink.

Maybe just write this down in a big fat comment?