Re: [PATCH 39/39] xfs_scrub: create online filesystem scrub program

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Sat, Nov 05, 2016 at 01:22:56PM +0800, Eryu Guan wrote:
> On Fri, Nov 04, 2016 at 05:28:44PM -0700, Darrick J. Wong wrote:
> > Create a filesystem scrubbing tool that walks the directory tree,
> > queries every file's extents, extended attributes, and stat data.  For
> > generic (non-XFS) filesystems this depends on the kernel to do nearly
> > all the validation.  Optionally, we can (try to) read all the file
> > data.
> > 
> > For XFS, we perform sequential scans of each AG's metadata, inodes,
> > extent maps, and file data.  Being XFS specific, we can work with
> > the in-kernel scrubbers to perform much stronger
> > metadata checking and cross-referencing.  We can also take advantage
> > of newer ioctls such as GETFSMAP to perform faster read verification.
> > 
> > In the future we will be able to take advantage of (still unwritten)
> > features such as parent directory pointers to fully validate all
> > metadata.  However, this tool /should/ work for most non-XFS
> > filesystems such as ext4 and btrfs.
> > 
> > Note also that the scrub tool can shut down the filesystem if errors
> > are found.  This is not a default option since scrubbing is very
> > immature at this time.  It can also ask the XFS driver in the kernel
> > to optimize or repair metadata, though this may not be successful.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> [snip]
> > --- /dev/null
> > +++ b/scrub/scrub.c
> > @@ -0,0 +1,1009 @@
> > +/*
> > + * Copyright (C) 2016 Oracle.  All Rights Reserved.
> > + *
> > + * Author: Darrick J. Wong <darrick.wong@oracle.com>
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License
> > + * as published by the Free Software Foundation; either version 2
> > + * of the License, or (at your option) any later version.
> > + *
> > + * This program is distributed in the hope that it would be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License
> > + * along with this program; if not, write the Free Software Foundation,
> > + * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
> > + */
> > +#include "libxfs.h"
> > +#include <stdio.h>
> > +#include <mntent.h>
> > +#include <unistd.h>
> > +#include <sys/types.h>
> > +#include <sys/stat.h>
> > +#include <sys/time.h>
> > +#include <sys/resource.h>
> > +#include <sys/statvfs.h>
> > +#include <sys/vfs.h>
> > +#include <fcntl.h>
> > +#include <dirent.h>
> > +#include "disk.h"
> > +#include "scrub.h"
> > +#include "../../repair/threads.h"
> 
> I have trouble compiling the djwong-devel branch, it failed to find
> "../../repair/threads.h", seems it should be "../repair/threads.h" here.

Doh.  Yeah.  I'll fix that in the morning.  Sorry about that.

In a nutshell: I build xfsprogs git for each arch in a build-$arch/ subdirs
containing symlinks to everything in the parent, which is why I never tripped
on this. :/

--D

> 
> Thanks,
> Eryu