xfs: encode the rtbitmap in big endian format

Currently, the ondisk realtime bitmap file is 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.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 016ee4f..cd9457e 100644 (file)
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -709,10 +709,12 @@ struct xfs_agfl {
 
 /*
  * Realtime bitmap information is 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_rtword_raw {
        __u32           old;
+       __be32          rtg;
 };
 
 /*

diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
index 2286a98..f9c0d24 100644 (file)
--- a/fs/xfs/libxfs/xfs_rtbitmap.h
+++ b/fs/xfs/libxfs/xfs_rtbitmap.h
@@ -210,6 +210,8 @@ xfs_rtbitmap_getword(
 {
        union xfs_rtword_raw    *word = xfs_rbmblock_wordptr(args, index);
 
+       if (xfs_has_rtgroups(args->mp))
+               return be32_to_cpu(word->rtg);
        return word->old;
 }
 
@@ -222,7 +224,10 @@ xfs_rtbitmap_setword(
 {
        union xfs_rtword_raw    *word = xfs_rbmblock_wordptr(args, index);
 
-       word->old = value;
+       if (xfs_has_rtgroups(args->mp))
+               word->rtg = cpu_to_be32(value);
+       else
+               word->old = value;
 }
 
 /*