Re: [PATCH 4/6] xfs_scrub: handle concurrent directory updates during name scan

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

On Tue, Feb 09, 2021 at 09:30:32AM +0000, Christoph Hellwig wrote:
> On Mon, Feb 08, 2021 at 08:11:38PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > The name scanner in xfs_scrub cannot lock a namespace (dirent or xattr)
> > and the kernel does not provide a stable cursor interface, which means
> > that we can see the same byte sequence multiple times during a scan.
> > This isn't a confusing name error since the kernel enforces uniqueness
> > on the byte sequence, so all we need to do here is update the old entry.
> 
> So we get the same name but a different ino?  I guess that can happen
> with a replacing rename.  Maybe state that more clearly?

Ok, the paragraph now reads:

"The name scanner in xfs_scrub cannot lock a namespace (dirent or xattr)
and the kernel does not provide a stable cursor interface, which means
that we can see the same byte sequence multiple times during a scan if
other processes are performing replacing renames on the directory
simultaneously.  This isn't a confusing name error since the kernel
enforces uniqueness on the byte sequence, so all we need to do here is
update the old entry."

--D

> 
> Otherwise looks good:
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>