[PATCH v2 1/5] xfs_repair: refuse to run if we don't recognize version or feature flags

[Fanael Linithien]

 > Apparently xfs_repair running on a v5 filesystem doesn't check the
 > compat, rocompat, or incompat feature flags for bits that it doesn't
 > know about, which means that old xfs_repairs can wreak havoc. So,
 > strengthen the checks to prevent repair from "repairing" anything it
 > doesn't understand.
 >
 > v2: Move the complaint code after the version number check, and print
 > the actual feature bits that we don't recognize.
 >
 > Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
 > ---
 >  repair/versions.c |   33 +++++++++++++++++++++++++++++++++
 >  1 file changed, 33 insertions(+)
 >
 > diff --git a/repair/versions.c b/repair/versions.c
 > index c1dff72..dbe41a4 100644
 > --- a/repair/versions.c
 > +++ b/repair/versions.c
 > @@ -175,6 +175,39 @@ _("WARNING:  you have disallowed 
superblock-feature-bits-allowed\n"
 >          }
 >      }
 >
 > +    /* Look for V5 feature flags we don't know about */
 > +    if (XFS_SB_VERSION_NUM(sb) >= XFS_SB_VERSION_5) {
 > +        if (xfs_sb_has_ro_compat_feature(sb,
 > +                XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) {
 > +            do_warn(
 > +_("Superblock has unknown read-only compatible features (0x%x) 
enabled.\n"
 > +"Using a more recent xfs_repair is recommended.\n"),
 > +                sb->sb_features_ro_compat &
 > +                        XFS_SB_FEAT_RO_COMPAT_UNKNOWN);
 > +            issue_warning = 1;
 > +        }
 > +        if (xfs_sb_has_incompat_feature(sb,
 > +                XFS_SB_FEAT_INCOMPAT_UNKNOWN)) {
 > +            do_warn(
 > +_("Superblock has unknown read-only compatible features (0x%x) 
enabled.\n"
 > +"Using a more recent xfs_repair is recommended.\n"),
 > +                sb->sb_features_ro_compat &
 > +                        XFS_SB_FEAT_RO_COMPAT_UNKNOWN);

Copy/paste error, do you mean incompat?

 > +            issue_warning = 1;
 > +        }
 > +        if (xfs_sb_has_compat_feature(sb,
 > +                XFS_SB_FEAT_COMPAT_UNKNOWN)) {
 > +            do_warn(
 > +_("Superblock has unknown compatible features (0x%x) enabled.\n"
 > +"Using a more recent xfs_repair is recommended.\n"),
 > +                sb->sb_features_ro_compat &
 > +                        XFS_SB_FEAT_RO_COMPAT_UNKNOWN);

compat here?

 > +            issue_warning = 1;
 > +        }
 > +        if (issue_warning)
 > +            return 1;
 > +    }
 > +
 >      if (xfs_sb_version_hasattr(sb))  {
 >          if (!fs_attributes_allowed)  {
 >              if (!no_modify)  {