[14/52] xfs: encode the rtbitmap in little endian format

Commit Message

Darrick J. Wong Dec. 31, 2023, 11:51 p.m. UTC

From: Darrick J. Wong <[e-mail]>

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.

The natural format of a bitmap is (IMHO) little endian, because the byte
offsets of the bitmap data should always increase in step with the
information being indexed.

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 libxfs/xfs_format.h   |    4 +++-
 libxfs/xfs_rtbitmap.h |    7 ++++++-
 repair/rt.c           |    5 ++++-
 3 files changed, 13 insertions(+), 3 deletions(-)

Patch

diff --git a/libxfs/xfs_format.h b/libxfs/xfs_format.h
index 7178bd463c1..77422fbd337 100644
--- a/libxfs/xfs_format.h
+++ b/libxfs/xfs_format.h
@@ -749,10 +749,12 @@  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 le32 ondisk.
  */
 union xfs_rtword_raw {
 	__u32		old;
+	__le32		rtg;
 };
 
 /*
diff --git a/libxfs/xfs_rtbitmap.h b/libxfs/xfs_rtbitmap.h
index e1cf47d2a92..588689e53ba 100644
--- a/libxfs/xfs_rtbitmap.h
+++ b/libxfs/xfs_rtbitmap.h
@@ -208,6 +208,8 @@  xfs_rtbitmap_getword(
 {
 	union xfs_rtword_raw	*word = xfs_rbmblock_wordptr(args, index);
 
+	if (xfs_has_rtgroups(args->mp))
+		return le32_to_cpu(word->rtg);
 	return word->old;
 }
 
@@ -220,7 +222,10 @@  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_le32(value);
+	else
+		word->old = value;
 }
 
 /*
diff --git a/repair/rt.c b/repair/rt.c
index e49487829af..c2b2c25ff79 100644
--- a/repair/rt.c
+++ b/repair/rt.c
@@ -49,7 +49,10 @@  set_rtword(
 	union xfs_rtword_raw	*word,
 	xfs_rtword_t		value)
 {
-	word->old = value;
+	if (xfs_has_rtgroups(mp))
+		word->rtg = cpu_to_le32(value);
+	else
+		word->old = value;
 }
 
 static inline void