[PATCH 12/36] xfs: encode the rtbitmap in big endian format

Darrick J. Wong
2024-10-11T01:04:49Z

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>
---
fs/xfs/libxfs/xfs_format.h | 4 +++-
fs/xfs/libxfs/xfs_rtbitmap.h | 7 ++++++-
2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 3b51ba84128466..728e3cf5ad3221 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -736,10 +736,12 @@ 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 2286a98ecb32bb..f9c0d241590104 100644
--- 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;
}

/*