xfs: encode the rtsummary in big endian format

Currently, the ondisk realtime summary file counters are accessed in
units of 32-bit words.  There's no endian translation of the contents of
this file, which means that the Bad Things Happen(tm) if you go from
(say) x86 to powerpc.  Since we have a new feature flag, let's take the
opportunity to enforce an endianness on the file.  Encode the summary
information in big endian format, like most of the rest of the
filesystem.

Signed-off-by: Darrick J. Wong <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>

Author: Darrick J. Wong

fs/xfs/libxfs/xfs_format.h

@@ -719,10 +719,12 @@ union xfs_rtword_raw {
 
 /*
  * Realtime summary counts are accessed by the word, which is currently
- * stored in host-endian format.
+ * stored in host-endian format.  Starting with the realtime groups feature,
+ * the words are stored in be32 ondisk.
  */
 union xfs_suminfo_raw {
 	__u32		old;
+	__be32		rtg;
 };
 
 /*

fs/xfs/libxfs/xfs_rtbitmap.h

@@ -300,6 +300,8 @@ xfs_suminfo_get(
 {
 	union xfs_suminfo_raw	*info = xfs_rsumblock_infoptr(args, index);
 
+	if (xfs_has_rtgroups(args->mp))
+		return be32_to_cpu(info->rtg);
 	return info->old;
 }
 
@@ -312,6 +314,11 @@ xfs_suminfo_add(
 {
 	union xfs_suminfo_raw	*info = xfs_rsumblock_infoptr(args, index);
 
+	if (xfs_has_rtgroups(args->mp)) {
+		be32_add_cpu(&info->rtg, delta);
+		return be32_to_cpu(info->rtg);
+	}
+
 	info->old += delta;
 	return info->old;
 }

fs/xfs/scrub/rtsummary.c

@@ -151,6 +151,11 @@ xchk_rtsum_inc(
 	struct xfs_mount	*mp,
 	union xfs_suminfo_raw	*v)
 {
+	if (xfs_has_rtgroups(mp)) {
+		be32_add_cpu(&v->rtg, 1);
+		return be32_to_cpu(v->rtg);
+	}
+
 	v->old += 1;
 	return v->old;
 }