Merge tag 'refactor-rtbitmap-accessors-6.7_2023-10-19' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.7-mergeA

xfs: refactor rtbitmap/summary accessors [v1.2]

Since the rtbitmap and rtsummary accessor functions have proven more
controversial than the rest of the macro refactoring, split the patchset
into two to make review easier.

v1.1: various cleanups suggested by hch
v1.2: rework the accessor functions to reduce the amount of cursor
      tracking required, and create explicit bitmap/summary logging
      functions

With a bit of luck, this should all go splendidly.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'refactor-rtbitmap-accessors-6.7_2023-10-19' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: use accessor functions for summary info words
  xfs: create helpers for rtsummary block/wordcount computations
  xfs: use accessor functions for bitmap words
  xfs: create a helper to handle logging parts of rt bitmap/summary blocks

8 files changed, 223 insertions, 125 deletions

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index d48e3a395bd9..9a88aba1589f 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -691,6 +691,22 @@ struct xfs_agfl {
 		   xfs_daddr_to_agno(mp, (d) + (len) - 1)))
 
 /*
+ * Realtime bitmap information is accessed by the word, which is currently
+ * stored in host-endian format.
+ */
+union xfs_rtword_raw {
+	__u32		old;
+};
+
+/*
+ * Realtime summary counts are accessed by the word, which is currently
+ * stored in host-endian format.
+ */
+union xfs_suminfo_raw {
+	__u32		old;
+};
+
+/*
  * XFS Timestamps
  * ==============
  *
diff --git a/fs/xfs/libxfs/xfs_rtbitmap.c b/fs/xfs/libxfs/xfs_rtbitmap.c
index aefa2b0747a5..4221f539615f 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.c
+++ b/fs/xfs/libxfs/xfs_rtbitmap.c
@@ -99,7 +99,6 @@ xfs_rtfind_back(
 	xfs_rtxnum_t	limit,		/* last rtext to look at */
 	xfs_rtxnum_t	*rtx)		/* out: start rtext found */
 {
-	xfs_rtword_t	*b;		/* current word in buffer */
 	int		bit;		/* bit number in the word */
 	xfs_fileoff_t	block;		/* bitmap block number */
 	struct xfs_buf	*bp;		/* buf for the block */
@@ -110,6 +109,7 @@ xfs_rtfind_back(
 	xfs_rtword_t	mask;		/* mask of relevant bits for value */
 	xfs_rtword_t	want;		/* mask for "good" values */
 	xfs_rtword_t	wdiff;		/* difference from wanted value */
+	xfs_rtword_t	incore;
 	unsigned int	word;		/* word number in the buffer */
 
 	/*
@@ -125,14 +125,14 @@ xfs_rtfind_back(
 	 * Get the first word's index & point to it.
 	 */
 	word = xfs_rtx_to_rbmword(mp, start);
-	b = xfs_rbmblock_wordptr(bp, word);
 	bit = (int)(start & (XFS_NBWORD - 1));
 	len = start - limit + 1;
 	/*
 	 * Compute match value, based on the bit at start: if 1 (free)
 	 * then all-ones, else all-zeroes.
 	 */
-	want = (*b & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
+	incore = xfs_rtbitmap_getword(bp, word);
+	want = (incore & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
 	/*
 	 * If the starting position is not word-aligned, deal with the
 	 * partial word.
@@ -149,7 +149,7 @@ xfs_rtfind_back(
 		 * Calculate the difference between the value there
 		 * and what we're looking for.
 		 */
-		if ((wdiff = (*b ^ want) & mask)) {
+		if ((wdiff = (incore ^ want) & mask)) {
 			/*
 			 * Different.  Mark where we are and return.
 			 */
@@ -174,12 +174,6 @@ xfs_rtfind_back(
 			}
 
 			word = mp->m_blockwsize - 1;
-			b = xfs_rbmblock_wordptr(bp, word);
-		} else {
-			/*
-			 * Go on to the previous word in the buffer.
-			 */
-			b--;
 		}
 	} else {
 		/*
@@ -195,7 +189,8 @@ xfs_rtfind_back(
 		/*
 		 * Compute difference between actual and desired value.
 		 */
-		if ((wdiff = *b ^ want)) {
+		incore = xfs_rtbitmap_getword(bp, word);
+		if ((wdiff = incore ^ want)) {
 			/*
 			 * Different, mark where we are and return.
 			 */
@@ -220,12 +215,6 @@ xfs_rtfind_back(
 			}
 
 			word = mp->m_blockwsize - 1;
-			b = xfs_rbmblock_wordptr(bp, word);
-		} else {
-			/*
-			 * Go on to the previous word in the buffer.
-			 */
-			b--;
 		}
 	}
 	/*
@@ -242,7 +231,8 @@ xfs_rtfind_back(
 		/*
 		 * Compute difference between actual and desired value.
 		 */
-		if ((wdiff = (*b ^ want) & mask)) {
+		incore = xfs_rtbitmap_getword(bp, word);
+		if ((wdiff = (incore ^ want) & mask)) {
 			/*
 			 * Different, mark where we are and return.
 			 */
@@ -273,7 +263,6 @@ xfs_rtfind_forw(
 	xfs_rtxnum_t	limit,		/* last rtext to look at */
 	xfs_rtxnum_t	*rtx)		/* out: start rtext found */
 {
-	xfs_rtword_t	*b;		/* current word in buffer */
 	int		bit;		/* bit number in the word */
 	xfs_fileoff_t	block;		/* bitmap block number */
 	struct xfs_buf	*bp;		/* buf for the block */
@@ -284,6 +273,7 @@ xfs_rtfind_forw(
 	xfs_rtword_t	mask;		/* mask of relevant bits for value */
 	xfs_rtword_t	want;		/* mask for "good" values */
 	xfs_rtword_t	wdiff;		/* difference from wanted value */
+	xfs_rtword_t	incore;
 	unsigned int	word;		/* word number in the buffer */
 
 	/*
@@ -299,14 +289,14 @@ xfs_rtfind_forw(
 	 * Get the first word's index & point to it.
 	 */
 	word = xfs_rtx_to_rbmword(mp, start);
-	b = xfs_rbmblock_wordptr(bp, word);
 	bit = (int)(start & (XFS_NBWORD - 1));
 	len = limit - start + 1;
 	/*
 	 * Compute match value, based on the bit at start: if 1 (free)
 	 * then all-ones, else all-zeroes.
 	 */
-	want = (*b & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
+	incore = xfs_rtbitmap_getword(bp, word);
+	want = (incore & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
 	/*
 	 * If the starting position is not word-aligned, deal with the
 	 * partial word.
@@ -322,7 +312,7 @@ xfs_rtfind_forw(
 		 * Calculate the difference between the value there
 		 * and what we're looking for.
 		 */
-		if ((wdiff = (*b ^ want) & mask)) {
+		if ((wdiff = (incore ^ want) & mask)) {
 			/*
 			 * Different.  Mark where we are and return.
 			 */
@@ -347,12 +337,6 @@ xfs_rtfind_forw(
 			}
 
 			word = 0;
-			b = xfs_rbmblock_wordptr(bp, word);
-		} else {
-			/*
-			 * Go on to the previous word in the buffer.
-			 */
-			b++;
 		}
 	} else {
 		/*
@@ -368,7 +352,8 @@ xfs_rtfind_forw(
 		/*
 		 * Compute difference between actual and desired value.
 		 */
-		if ((wdiff = *b ^ want)) {
+		incore = xfs_rtbitmap_getword(bp, word);
+		if ((wdiff = incore ^ want)) {
 			/*
 			 * Different, mark where we are and return.
 			 */
@@ -393,12 +378,6 @@ xfs_rtfind_forw(
 			}
 
 			word = 0;
-			b = xfs_rbmblock_wordptr(bp, word);
-		} else {
-			/*
-			 * Go on to the next word in the buffer.
-			 */
-			b++;
 		}
 	}
 	/*
@@ -413,7 +392,8 @@ xfs_rtfind_forw(
 		/*
 		 * Compute difference between actual and desired value.
 		 */
-		if ((wdiff = (*b ^ want) & mask)) {
+		incore = xfs_rtbitmap_getword(bp, word);
+		if ((wdiff = (incore ^ want) & mask)) {
 			/*
 			 * Different, mark where we are and return.
 			 */
@@ -432,6 +412,21 @@ xfs_rtfind_forw(
 	return 0;
 }
 
+/* Log rtsummary counter at @infoword. */
+static inline void
+xfs_trans_log_rtsummary(
+	struct xfs_trans	*tp,
+	struct xfs_buf		*bp,
+	unsigned int		infoword)
+{
+	size_t			first, last;
+
+	first = (void *)xfs_rsumblock_infoptr(bp, infoword) - bp->b_addr;
+	last = first + sizeof(xfs_suminfo_t) - 1;
+
+	xfs_trans_log_buf(tp, bp, first, last);
+}
+
 /*
  * Read and/or modify the summary information for a given extent size,
  * bitmap block combination.
@@ -456,7 +451,6 @@ xfs_rtmodify_summary_int(
 	int		error;		/* error value */
 	xfs_fileoff_t	sb;		/* summary fsblock */
 	xfs_rtsumoff_t	so;		/* index into the summary file */
-	xfs_suminfo_t	*sp;		/* pointer to returned data */
 	unsigned int	infoword;
 
 	/*
@@ -495,21 +489,21 @@ xfs_rtmodify_summary_int(
 	 * Point to the summary information, modify/log it, and/or copy it out.
 	 */
 	infoword = xfs_rtsumoffs_to_infoword(mp, so);
-	sp = xfs_rsumblock_infoptr(bp, infoword);
 	if (delta) {
-		uint first = (uint)((char *)sp - (char *)bp->b_addr);
+		xfs_suminfo_t	val = xfs_suminfo_add(bp, infoword, delta);
 
-		*sp += delta;
 		if (mp->m_rsum_cache) {
-			if (*sp == 0 && log == mp->m_rsum_cache[bbno])
+			if (val == 0 && log == mp->m_rsum_cache[bbno])
 				mp->m_rsum_cache[bbno]++;
-			if (*sp != 0 && log < mp->m_rsum_cache[bbno])
+			if (val != 0 && log < mp->m_rsum_cache[bbno])
 				mp->m_rsum_cache[bbno] = log;
 		}
-		xfs_trans_log_buf(tp, bp, first, first + sizeof(*sp) - 1);
+		xfs_trans_log_rtsummary(tp, bp, infoword);
+		if (sum)
+			*sum = val;
+	} else if (sum) {
+		*sum = xfs_suminfo_get(bp, infoword);
 	}
-	if (sum)
-		*sum = *sp;
 	return 0;
 }
 
@@ -527,6 +521,22 @@ xfs_rtmodify_summary(
 					delta, rbpp, rsb, NULL);
 }
 
+/* Log rtbitmap block from the word @from to the byte before @next. */
+static inline void
+xfs_trans_log_rtbitmap(
+	struct xfs_trans	*tp,
+	struct xfs_buf		*bp,
+	unsigned int		from,
+	unsigned int		next)
+{
+	size_t			first, last;
+
+	first = (void *)xfs_rbmblock_wordptr(bp, from) - bp->b_addr;
+	last = ((void *)xfs_rbmblock_wordptr(bp, next) - 1) - bp->b_addr;
+
+	xfs_trans_log_buf(tp, bp, first, last);
+}
+
 /*
  * Set the given range of bitmap bits to the given value.
  * Do whatever I/O and logging is required.
@@ -539,15 +549,15 @@ xfs_rtmodify_range(
 	xfs_rtxlen_t	len,		/* length of extent to modify */
 	int		val)		/* 1 for free, 0 for allocated */
 {
-	xfs_rtword_t	*b;		/* current word in buffer */
 	int		bit;		/* bit number in the word */
 	xfs_fileoff_t	block;		/* bitmap block number */
 	struct xfs_buf	*bp;		/* buf for the block */
 	int		error;		/* error value */
-	xfs_rtword_t	*first;		/* first used word in the buffer */
 	int		i;		/* current bit number rel. to start */
 	int		lastbit;	/* last useful bit in word */
 	xfs_rtword_t	mask;		/* mask o frelevant bits for value */
+	xfs_rtword_t	incore;
+	unsigned int	firstword;	/* first word used in the buffer */
 	unsigned int	word;		/* word number in the buffer */
 
 	/*
@@ -565,8 +575,7 @@ xfs_rtmodify_range(
 	/*
 	 * Compute the starting word's address, and starting bit.
 	 */
-	word = xfs_rtx_to_rbmword(mp, start);
-	first = b = xfs_rbmblock_wordptr(bp, word);
+	firstword = word = xfs_rtx_to_rbmword(mp, start);
 	bit = (int)(start & (XFS_NBWORD - 1));
 	/*
 	 * 0 (allocated) => all zeroes; 1 (free) => all ones.
@@ -585,10 +594,12 @@ xfs_rtmodify_range(
 		/*
 		 * Set/clear the active bits.
 		 */
+		incore = xfs_rtbitmap_getword(bp, word);
 		if (val)
-			*b |= mask;
+			incore |= mask;
 		else
-			*b &= ~mask;
+			incore &= ~mask;
+		xfs_rtbitmap_setword(bp, word, incore);
 		i = lastbit - bit;
 		/*
 		 * Go on to the next block if that's where the next word is
@@ -599,21 +610,13 @@ xfs_rtmodify_range(
 			 * Log the changed part of this block.
 			 * Get the next one.
 			 */
-			xfs_trans_log_buf(tp, bp,
-				(uint)((char *)first - (char *)bp->b_addr),
-				(uint)((char *)b - (char *)bp->b_addr));
+			xfs_trans_log_rtbitmap(tp, bp, firstword, word);
 			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
 			if (error) {
 				return error;
 			}
 
-			word = 0;
-			first = b = xfs_rbmblock_wordptr(bp, word);
-		} else {
-			/*
-			 * Go on to the next word in the buffer
-			 */
-			b++;
+			firstword = word = 0;
 		}
 	} else {
 		/*
@@ -629,7 +632,7 @@ xfs_rtmodify_range(
 		/*
 		 * Set the word value correctly.
 		 */
-		*b = val;
+		xfs_rtbitmap_setword(bp, word, val);
 		i += XFS_NBWORD;
 		/*
 		 * Go on to the next block if that's where the next word is
@@ -640,21 +643,13 @@ xfs_rtmodify_range(
 			 * Log the changed part of this block.
 			 * Get the next one.
 			 */
-			xfs_trans_log_buf(tp, bp,
-				(uint)((char *)first - (char *)bp->b_addr),
-				(uint)((char *)b - (char *)bp->b_addr));
+			xfs_trans_log_rtbitmap(tp, bp, firstword, word);
 			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
 			if (error) {
 				return error;
 			}
 
-			word = 0;
-			first = b = xfs_rbmblock_wordptr(bp, word);
-		} else {
-			/*
-			 * Go on to the next word in the buffer
-			 */
-			b++;
+			firstword = word = 0;
 		}
 	}
 	/*
@@ -669,19 +664,19 @@ xfs_rtmodify_range(
 		/*
 		 * Set/clear the active bits.
 		 */
+		incore = xfs_rtbitmap_getword(bp, word);
 		if (val)
-			*b |= mask;
+			incore |= mask;
 		else
-			*b &= ~mask;
-		b++;
+			incore &= ~mask;
+		xfs_rtbitmap_setword(bp, word, incore);
+		word++;
 	}
 	/*
 	 * Log any remaining changed bytes.
 	 */
-	if (b > first)
-		xfs_trans_log_buf(tp, bp,
-			(uint)((char *)first - (char *)bp->b_addr),
-			(uint)((char *)b - (char *)bp->b_addr - 1));
+	if (word > firstword)
+		xfs_trans_log_rtbitmap(tp, bp, firstword, word);
 	return 0;
 }
 
@@ -775,7 +770,6 @@ xfs_rtcheck_range(
 	xfs_rtxnum_t	*new,		/* out: first rtext not matching */
 	int		*stat)		/* out: 1 for matches, 0 for not */
 {
-	xfs_rtword_t	*b;		/* current word in buffer */
 	int		bit;		/* bit number in the word */
 	xfs_fileoff_t	block;		/* bitmap block number */
 	struct xfs_buf	*bp;		/* buf for the block */
@@ -784,6 +778,7 @@ xfs_rtcheck_range(
 	xfs_rtxnum_t	lastbit;	/* last useful bit in word */
 	xfs_rtword_t	mask;		/* mask of relevant bits for value */
 	xfs_rtword_t	wdiff;		/* difference from wanted value */
+	xfs_rtword_t	incore;
 	unsigned int	word;		/* word number in the buffer */
 
 	/*
@@ -802,7 +797,6 @@ xfs_rtcheck_range(
 	 * Compute the starting word's address, and starting bit.
 	 */
 	word = xfs_rtx_to_rbmword(mp, start);
-	b = xfs_rbmblock_wordptr(bp, word);
 	bit = (int)(start & (XFS_NBWORD - 1));
 	/*
 	 * 0 (allocated) => all zero's; 1 (free) => all one's.
@@ -824,7 +818,8 @@ xfs_rtcheck_range(
 		/*
 		 * Compute difference between actual and desired value.
 		 */
-		if ((wdiff = (*b ^ val) & mask)) {
+		incore = xfs_rtbitmap_getword(bp, word);
+		if ((wdiff = (incore ^ val) & mask)) {
 			/*
 			 * Different, compute first wrong bit and return.
 			 */
@@ -850,12 +845,6 @@ xfs_rtcheck_range(
 			}
 
 			word = 0;
-			b = xfs_rbmblock_wordptr(bp, word);
-		} else {
-			/*
-			 * Go on to the next word in the buffer.
-			 */
-			b++;
 		}
 	} else {
 		/*
@@ -871,7 +860,8 @@ xfs_rtcheck_range(
 		/*
 		 * Compute difference between actual and desired value.
 		 */
-		if ((wdiff = *b ^ val)) {
+		incore = xfs_rtbitmap_getword(bp, word);
+		if ((wdiff = incore ^ val)) {
 			/*
 			 * Different, compute first wrong bit and return.
 			 */
@@ -897,12 +887,6 @@ xfs_rtcheck_range(
 			}
 
 			word = 0;
-			b = xfs_rbmblock_wordptr(bp, word);
-		} else {
-			/*
-			 * Go on to the next word in the buffer.
-			 */
-			b++;
 		}
 	}
 	/*
@@ -917,7 +901,8 @@ xfs_rtcheck_range(
 		/*
 		 * Compute difference between actual and desired value.
 		 */
-		if ((wdiff = (*b ^ val) & mask)) {
+		incore = xfs_rtbitmap_getword(bp, word);
+		if ((wdiff = (incore ^ val) & mask)) {
 			/*
 			 * Different, compute first wrong bit and return.
 			 */
@@ -1162,3 +1147,32 @@ xfs_rtbitmap_wordcount(
 	blocks = xfs_rtbitmap_blockcount(mp, rtextents);
 	return XFS_FSB_TO_B(mp, blocks) >> XFS_WORDLOG;
 }
+
+/* Compute the number of rtsummary blocks needed to track the given rt space. */
+xfs_filblks_t
+xfs_rtsummary_blockcount(
+	struct xfs_mount	*mp,
+	unsigned int		rsumlevels,
+	xfs_extlen_t		rbmblocks)
+{
+	unsigned long long	rsumwords;
+
+	rsumwords = (unsigned long long)rsumlevels * rbmblocks;
+	return XFS_B_TO_FSB(mp, rsumwords << XFS_WORDLOG);
+}
+
+/*
+ * Compute the number of rtsummary info words needed to populate every block of
+ * a summary file that is large enough to track the given rt space.
+ */
+unsigned long long
+xfs_rtsummary_wordcount(
+	struct xfs_mount	*mp,
+	unsigned int		rsumlevels,
+	xfs_extlen_t		rbmblocks)
+{
+	xfs_filblks_t		blocks;
+
+	blocks = xfs_rtsummary_blockcount(mp, rsumlevels, rbmblocks);
+	return XFS_FSB_TO_B(mp, blocks) >> XFS_WORDLOG;
+}
diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
index 01eabb9b5516..fdfa98e0ee52 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.h
+++ b/fs/xfs/libxfs/xfs_rtbitmap.h
@@ -159,16 +159,39 @@ xfs_rbmblock_to_rtx(
 }
 
 /* Return a pointer to a bitmap word within a rt bitmap block. */
-static inline xfs_rtword_t *
+static inline union xfs_rtword_raw *
 xfs_rbmblock_wordptr(
 	struct xfs_buf		*bp,
 	unsigned int		index)
 {
-	xfs_rtword_t		*words = bp->b_addr;
+	union xfs_rtword_raw	*words = bp->b_addr;
 
 	return words + index;
 }
 
+/* Convert an ondisk bitmap word to its incore representation. */
+static inline xfs_rtword_t
+xfs_rtbitmap_getword(
+	struct xfs_buf		*bp,
+	unsigned int		index)
+{
+	union xfs_rtword_raw	*word = xfs_rbmblock_wordptr(bp, index);
+
+	return word->old;
+}
+
+/* Set an ondisk bitmap word from an incore representation. */
+static inline void
+xfs_rtbitmap_setword(
+	struct xfs_buf		*bp,
+	unsigned int		index,
+	xfs_rtword_t		value)
+{
+	union xfs_rtword_raw	*word = xfs_rbmblock_wordptr(bp, index);
+
+	word->old = value;
+}
+
 /*
  * Convert a rt extent length and rt bitmap block number to a xfs_suminfo_t
  * offset within the rt summary file.
@@ -209,16 +232,40 @@ xfs_rtsumoffs_to_infoword(
 }
 
 /* Return a pointer to a summary info word within a rt summary block. */
-static inline xfs_suminfo_t *
+static inline union xfs_suminfo_raw *
 xfs_rsumblock_infoptr(
 	struct xfs_buf		*bp,
 	unsigned int		index)
 {
-	xfs_suminfo_t		*info = bp->b_addr;
+	union xfs_suminfo_raw	*info = bp->b_addr;
 
 	return info + index;
 }
 
+/* Get the current value of a summary counter. */
+static inline xfs_suminfo_t
+xfs_suminfo_get(
+	struct xfs_buf		*bp,
+	unsigned int		index)
+{
+	union xfs_suminfo_raw	*info = xfs_rsumblock_infoptr(bp, index);
+
+	return info->old;
+}
+
+/* Add to the current value of a summary counter and return the new value. */
+static inline xfs_suminfo_t
+xfs_suminfo_add(
+	struct xfs_buf		*bp,
+	unsigned int		index,
+	int			delta)
+{
+	union xfs_suminfo_raw	*info = xfs_rsumblock_infoptr(bp, index);
+
+	info->old += delta;
+	return info->old;
+}
+
 /*
  * Functions for walking free space rtextents in the realtime bitmap.
  */
@@ -285,6 +332,11 @@ xfs_filblks_t xfs_rtbitmap_blockcount(struct xfs_mount *mp, xfs_rtbxlen_t
 		rtextents);
 unsigned long long xfs_rtbitmap_wordcount(struct xfs_mount *mp,
 		xfs_rtbxlen_t rtextents);
+
+xfs_filblks_t xfs_rtsummary_blockcount(struct xfs_mount *mp,
+		unsigned int rsumlevels, xfs_extlen_t rbmblocks);
+unsigned long long xfs_rtsummary_wordcount(struct xfs_mount *mp,
+		unsigned int rsumlevels, xfs_extlen_t rbmblocks);
 #else /* CONFIG_XFS_RT */
 # define xfs_rtfree_extent(t,b,l)			(-ENOSYS)
 # define xfs_rtfree_blocks(t,rb,rl)			(-ENOSYS)
@@ -299,6 +351,8 @@ xfs_rtbitmap_blockcount(struct xfs_mount *mp, xfs_rtbxlen_t rtextents)
 	return 0;
 }
 # define xfs_rtbitmap_wordcount(mp, r)			(0)
+# define xfs_rtsummary_blockcount(mp, l, b)		(0)
+# define xfs_rtsummary_wordcount(mp, l, b)		(0)
 #endif /* CONFIG_XFS_RT */
 
 #endif /* __XFS_RTBITMAP_H__ */
diff --git a/fs/xfs/scrub/rtsummary.c b/fs/xfs/scrub/rtsummary.c
index 0971d002d906..e9eac5354f19 100644
--- a/fs/xfs/scrub/rtsummary.c
+++ b/fs/xfs/scrub/rtsummary.c
@@ -82,9 +82,10 @@ static inline int
 xfsum_load(
 	struct xfs_scrub	*sc,
 	xfs_rtsumoff_t		sumoff,
-	xfs_suminfo_t		*info)
+	union xfs_suminfo_raw	*rawinfo)
 {
-	return xfile_obj_load(sc->xfile, info, sizeof(xfs_suminfo_t),
+	return xfile_obj_load(sc->xfile, rawinfo,
+			sizeof(union xfs_suminfo_raw),
 			sumoff << XFS_WORDLOG);
 }
 
@@ -92,9 +93,10 @@ static inline int
 xfsum_store(
 	struct xfs_scrub	*sc,
 	xfs_rtsumoff_t		sumoff,
-	const xfs_suminfo_t	info)
+	const union xfs_suminfo_raw rawinfo)
 {
-	return xfile_obj_store(sc->xfile, &info, sizeof(xfs_suminfo_t),
+	return xfile_obj_store(sc->xfile, &rawinfo,
+			sizeof(union xfs_suminfo_raw),
 			sumoff << XFS_WORDLOG);
 }
 
@@ -102,13 +104,22 @@ static inline int
 xfsum_copyout(
 	struct xfs_scrub	*sc,
 	xfs_rtsumoff_t		sumoff,
-	xfs_suminfo_t		*info,
+	union xfs_suminfo_raw	*rawinfo,
 	unsigned int		nr_words)
 {
-	return xfile_obj_load(sc->xfile, info, nr_words << XFS_WORDLOG,
+	return xfile_obj_load(sc->xfile, rawinfo, nr_words << XFS_WORDLOG,
 			sumoff << XFS_WORDLOG);
 }
 
+static inline xfs_suminfo_t
+xchk_rtsum_inc(
+	struct xfs_mount	*mp,
+	union xfs_suminfo_raw	*v)
+{
+	v->old += 1;
+	return v->old;
+}
+
 /* Update the summary file to reflect the free extent that we've accumulated. */
 STATIC int
 xchk_rtsum_record_free(
@@ -123,7 +134,8 @@ xchk_rtsum_record_free(
 	xfs_filblks_t			rtlen;
 	xfs_rtsumoff_t			offs;
 	unsigned int			lenlog;
-	xfs_suminfo_t			v = 0;
+	union xfs_suminfo_raw		v;
+	xfs_suminfo_t			value;
 	int				error = 0;
 
 	if (xchk_should_terminate(sc, &error))
@@ -147,9 +159,9 @@ xchk_rtsum_record_free(
 	if (error)
 		return error;
 
-	v++;
+	value = xchk_rtsum_inc(sc->mp, &v);
 	trace_xchk_rtsum_record_free(mp, rec->ar_startext, rec->ar_extcount,
-			lenlog, offs, v);
+			lenlog, offs, value);
 
 	return xfsum_store(sc, offs, v);
 }
@@ -184,7 +196,7 @@ xchk_rtsum_compare(
 	int			nmap;
 
 	for (off = 0; off < XFS_B_TO_FSB(mp, mp->m_rsumsize); off++) {
-		xfs_suminfo_t	*ondisk_info;
+		union xfs_suminfo_raw *ondisk_info;
 		int		error = 0;
 
 		if (xchk_should_terminate(sc, &error))
diff --git a/fs/xfs/scrub/trace.c b/fs/xfs/scrub/trace.c
index 46249e7b17e0..29afa4851235 100644
--- a/fs/xfs/scrub/trace.c
+++ b/fs/xfs/scrub/trace.c
@@ -13,6 +13,7 @@
 #include "xfs_inode.h"
 #include "xfs_btree.h"
 #include "xfs_ag.h"
+#include "xfs_rtbitmap.h"
 #include "scrub/scrub.h"
 #include "scrub/xfile.h"
 #include "scrub/xfarray.h"
diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index b0cf6757444f..4a8bc6f3c8f2 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -1038,8 +1038,8 @@ TRACE_EVENT(xfarray_sort_stats,
 TRACE_EVENT(xchk_rtsum_record_free,
 	TP_PROTO(struct xfs_mount *mp, xfs_rtxnum_t start,
 		 xfs_rtbxlen_t len, unsigned int log, loff_t pos,
-		 xfs_suminfo_t v),
-	TP_ARGS(mp, start, len, log, pos, v),
+		 xfs_suminfo_t value),
+	TP_ARGS(mp, start, len, log, pos, value),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
 		__field(dev_t, rtdev)
@@ -1047,7 +1047,7 @@ TRACE_EVENT(xchk_rtsum_record_free,
 		__field(unsigned long long, len)
 		__field(unsigned int, log)
 		__field(loff_t, pos)
-		__field(xfs_suminfo_t, v)
+		__field(xfs_suminfo_t, value)
 	),
 	TP_fast_assign(
 		__entry->dev = mp->m_super->s_dev;
@@ -1056,7 +1056,7 @@ TRACE_EVENT(xchk_rtsum_record_free,
 		__entry->len = len;
 		__entry->log = log;
 		__entry->pos = pos;
-		__entry->v = v;
+		__entry->value = value;
 	),
 	TP_printk("dev %d:%d rtdev %d:%d rtx 0x%llx rtxcount 0x%llx log %u rsumpos 0x%llx sumcount %u",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
@@ -1065,7 +1065,7 @@ TRACE_EVENT(xchk_rtsum_record_free,
 		  __entry->len,
 		  __entry->log,
 		  __entry->pos,
-		  __entry->v)
+		  __entry->value)
 );
 #endif /* CONFIG_XFS_RT */
 
diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/xfs_ondisk.h
index c4cc99b70dd3..21a7e350b4c5 100644
--- a/fs/xfs/xfs_ondisk.h
+++ b/fs/xfs/xfs_ondisk.h
@@ -72,6 +72,10 @@ xfs_check_ondisk_structs(void)
 	XFS_CHECK_STRUCT_SIZE(xfs_attr_leaf_map_t,		4);
 	XFS_CHECK_STRUCT_SIZE(xfs_attr_leaf_name_local_t,	4);
 
+	/* realtime structures */
+	XFS_CHECK_STRUCT_SIZE(union xfs_rtword_raw,		4);
+	XFS_CHECK_STRUCT_SIZE(union xfs_suminfo_raw,		4);
+
 	/*
 	 * m68k has problems with xfs_attr_leaf_name_remote_t, but we pad it to
 	 * 4 bytes anyway so it's not obviously a problem.  Hence for the moment
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 8e041df12640..3be6bda2fd92 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1001,8 +1001,7 @@ xfs_growfs_rt(
 	nrbmblocks = xfs_rtbitmap_blockcount(mp, nrextents);
 	nrextslog = xfs_highbit32(nrextents);
 	nrsumlevels = nrextslog + 1;
-	nrsumsize = (uint)sizeof(xfs_suminfo_t) * nrsumlevels * nrbmblocks;
-	nrsumblocks = XFS_B_TO_FSB(mp, nrsumsize);
+	nrsumblocks = xfs_rtsummary_blockcount(mp, nrsumlevels, nrbmblocks);
 	nrsumsize = XFS_FSB_TO_B(mp, nrsumblocks);
 	/*
 	 * New summary size can't be more than half the size of
@@ -1063,10 +1062,8 @@ xfs_growfs_rt(
 		ASSERT(nsbp->sb_rextents != 0);
 		nsbp->sb_rextslog = xfs_highbit32(nsbp->sb_rextents);
 		nrsumlevels = nmp->m_rsumlevels = nsbp->sb_rextslog + 1;
-		nrsumsize =
-			(uint)sizeof(xfs_suminfo_t) * nrsumlevels *
-			nsbp->sb_rbmblocks;
-		nrsumblocks = XFS_B_TO_FSB(mp, nrsumsize);
+		nrsumblocks = xfs_rtsummary_blockcount(mp, nrsumlevels,
+				nsbp->sb_rbmblocks);
 		nmp->m_rsumsize = nrsumsize = XFS_FSB_TO_B(mp, nrsumblocks);
 		/*
 		 * Start a transaction, get the log reservation.
@@ -1272,6 +1269,7 @@ xfs_rtmount_init(
 	struct xfs_buf		*bp;	/* buffer for last block of subvolume */
 	struct xfs_sb		*sbp;	/* filesystem superblock copy in mount */
 	xfs_daddr_t		d;	/* address of last block of subvolume */
+	unsigned int		rsumblocks;
 	int			error;
 
 	sbp = &mp->m_sb;
@@ -1283,10 +1281,9 @@ xfs_rtmount_init(
 		return -ENODEV;
 	}
 	mp->m_rsumlevels = sbp->sb_rextslog + 1;
-	mp->m_rsumsize =
-		(uint)sizeof(xfs_suminfo_t) * mp->m_rsumlevels *
-		sbp->sb_rbmblocks;
-	mp->m_rsumsize = roundup(mp->m_rsumsize, sbp->sb_blocksize);
+	rsumblocks = xfs_rtsummary_blockcount(mp, mp->m_rsumlevels,
+			mp->m_sb.sb_rbmblocks);
+	mp->m_rsumsize = XFS_FSB_TO_B(mp, rsumblocks);
 	mp->m_rbmip = mp->m_rsumip = NULL;
 	/*
 	 * Check that the realtime section is an ok size.