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

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: [PATCH] xfs_repair: allow filesystems with a single allocation group
From: Eric Sandeen <sandeen@xxxxxxxxxxx>
Date: Sun, 18 Jan 2009 13:35:39 -0600
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20090118173417.GA32597@xxxxxxxxxxxxx>
References: <20090105201942.GA6960@xxxxxxxxxxxxx> <20090118173417.GA32597@xxxxxxxxxxxxx>
User-agent: Thunderbird 2.0.0.19 (Macintosh/20081209)
Christoph Hellwig wrote:
> Lachlan, Eric,
> 
> does this version look okay now?

just minor edits on the manpage change, below

> 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.

"validated."

>> +Geometry information can not be validated if there is only a single

"can not be validated if only a single allocation group exists"

>> +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

"know what you are doing.  If in doubt, do a run"

>> +in no modify mode first.

in "no-modify" (-n) mode first.

>>  .RE
>>  .TP
>>  .B \-t " interval"
>>
>> _______________________________________________
>> xfs mailing list
>> xfs@xxxxxxxxxxx
>> http://oss.sgi.com/mailman/listinfo/xfs
> ---end quoted text---
> 
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