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Re: [PATCH] xfs_repair: allow filesystems with a single allocation group

To: xfs@xxxxxxxxxxx
Subject: Re: [PATCH] xfs_repair: allow filesystems with a single allocation group
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Sun, 18 Jan 2009 12:34:18 -0500
In-reply-to: <20090105201942.GA6960@xxxxxxxxxxxxx>
References: <20090105201942.GA6960@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.18 (2008-05-17)
Lachlan, Eric,

does this version look okay now?

On Mon, Jan 05, 2009 at 03:19:42PM -0500, Christoph Hellwig wrote:
> Currently xfs_repair bails out on a filesystem with just a single AG.
> But that's a perfectly valid configureation, so we should allow it.
> 
> Because we could cause harm only allow it when using the force_geometry
> suboption.  But we nice enough to tell the user about it when he needs it.
> 
> Also make sure to take the internal log into account when guestimating the
> first inode cluster offset.
> 
> I'll also cook up a testcase for repair on single AG filesystems.
> 
> 
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> Reported-By: Arkadiusz Miskiewicz <arekm@xxxxxxxx>
> 
> Index: xfsprogs-dev/repair/sb.c
> ===================================================================
> --- xfsprogs-dev.orig/repair/sb.c     2009-01-03 21:57:42.415546683 +0100
> +++ xfsprogs-dev/repair/sb.c  2009-01-05 21:19:01.706752325 +0100
> @@ -760,27 +760,37 @@ verify_set_primary_sb(xfs_sb_t          *rsb,
>       switch (num_sbs)  {
>       case 2:
>               /*
> -              * all them have to be right.  if not, report geometry
> -              * and get out unless force option is in effect (-F)
> +              * If we only have two allocation groups, and the superblock
> +              * in the second allocation group differs from the primary
> +              * superblock we can't verify the geometry information.
> +              * Warn the user about this situation and get out unless
> +              * explicitly overridden.
>                */
>               if (current->refs != 2)  {
>                       if (!force_geo)  {
>                               do_warn(
> -     _("Only two AGs detected and they do not match - cannot proceed.\n"));
> +     _("Only two AGs detected and they do not match - "
> +       "cannot validate filesystem geometry.\n"
> +       "Use the -o force_geometry option to proceed.\n"));
>                               exit(1);
>                       }
>               }
> -             break;
> +             goto out_free_list;
>       case 1:
>               /*
> -              * just report the geometry info and get out.
> -              * refuse to run further unless the force (-F)
> -              * option is in effect.
> +              * If we only have a single allocation group there is no
> +              * secondary superblock that we can use to verify the geometry
> +              * information.  Warn the user about this situation and get
> +              * out unless explicitly overridden.
>                */
>               if (!force_geo)  {
> -                     do_warn(_("Only one AG detected - cannot proceed.\n"));
> +                     do_warn(
> +     _("Only one AG detected - "
> +       "cannot validate filesystem geometry.\n"
> +       "Use the -o force_geometry option to proceed.\n"));
>                       exit(1);
>               }
> +             goto out_free_list;
>       default:
>               /*
>                * at least half of the probed superblocks have
> @@ -820,6 +830,7 @@ verify_set_primary_sb(xfs_sb_t            *rsb,
>               sb_width = sb->sb_width;
>       }
>  
> +out_free_list:
>       free_geo(list);
>  out:
>       free(sb);
> Index: xfsprogs-dev/repair/xfs_repair.c
> ===================================================================
> --- xfsprogs-dev.orig/repair/xfs_repair.c     2009-01-03 21:57:42.416547229 
> +0100
> +++ xfsprogs-dev/repair/xfs_repair.c  2009-01-05 20:53:24.810738262 +0100
> @@ -62,6 +62,8 @@ char *o_opts[] = {
>       "bhash",
>  #define      AG_STRIDE       4
>       "ag_stride",
> +#define FORCE_GEO    5
> +     "force_geometry",
>       NULL
>  };
>  
> @@ -258,6 +260,13 @@ process_args(int argc, char **argv)
>                               case AG_STRIDE:
>                                       ag_stride = (int)strtol(val, NULL, 0);
>                                       break;
> +                             case FORCE_GEO:
> +                                     if (val)
> +                                             noval('o', o_opts, FORCE_GEO);
> +                                     if (force_geo)
> +                                             respec('o', o_opts, FORCE_GEO);
> +                                     force_geo = 1;
> +                                     break;
>                               default:
>                                       unknown('o', val);
>                                       break;
> @@ -409,6 +418,19 @@ calc_mkfs(xfs_mount_t *mp)
>       fino_bno = inobt_root + XFS_MIN_FREELIST_RAW(1, 1, mp) + 1;
>  
>       /*
> +      * If we only have a single allocation group the log is also allocated
> +      * in the first allocation group and we need to add the number of
> +      * blocks used by the log to the above calculation.
> +      * All this of course doesn't apply if we have an external log.
> +      */
> +     if (mp->m_sb.sb_agcount == 1 && mp->m_sb.sb_logstart) {
> +             /*
> +              * XXX(hch): verify that sb_logstart makes sense?
> +              */
> +              fino_bno += mp->m_sb.sb_logblocks;
> +     }
> +
> +     /*
>        * ditto the location of the first inode chunks in the fs ('/')
>        */
>       if (xfs_sb_version_hasdalign(&mp->m_sb) && do_inoalign)  {
> Index: xfsprogs-dev/man/man8/xfs_repair.8
> ===================================================================
> --- xfsprogs-dev.orig/man/man8/xfs_repair.8   2009-01-05 21:11:50.054546919 
> +0100
> +++ xfsprogs-dev/man/man8/xfs_repair.8        2009-01-05 21:14:49.228027165 
> +0100
> @@ -146,6 +146,15 @@ RAM size.
>  This creates additional processing threads to parallel process
>  AGs that span multiple concat units. This can significantly
>  reduce repair times on concat based filesystems.
> +.TP
> +.BI force_geometry
> +Check the filesystem even if geometry information could not be validate.
> +Geometry information can not be validated if there is only a single
> +allocation group exists and thus no backups superblock exists, or
> +if there are two allocation groups and the two superblocks do not
> +agree on the filesystem geometry.  Only use this option if you validated
> +the geometry yourself and know what your doing.  In doubt do a run
> +in no modify mode first.
>  .RE
>  .TP
>  .B \-t " interval"
> 
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> xfs@xxxxxxxxxxx
> http://oss.sgi.com/mailman/listinfo/xfs
---end quoted text---

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