[PATCH 22/35] xfs: create helpers for rtbitmap block/wordcount computations

[cem@kernel.org]

From: "Darrick J. Wong" <djwong@kernel.org>

Source kernel commit: d0448fe76ac1a9ccbce574577a4c82246d17eec4

Create helper functions that compute the number of blocks or words
necessary to store the rt bitmap.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
---
 libxfs/xfs_rtbitmap.c   | 27 +++++++++++++++++++++++++++
 libxfs/xfs_rtbitmap.h   | 12 ++++++++++++
 libxfs/xfs_trans_resv.c |  9 +++++----
 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/libxfs/xfs_rtbitmap.c b/libxfs/xfs_rtbitmap.c
index 9a8bd93b7..92473d4a5 100644
--- a/libxfs/xfs_rtbitmap.c
+++ b/libxfs/xfs_rtbitmap.c
@@ -1137,3 +1137,30 @@ xfs_rtalloc_extent_is_free(
 	*is_free = matches;
 	return 0;
 }
+
+/*
+ * Compute the number of rtbitmap blocks needed to track the given number of rt
+ * extents.
+ */
+xfs_filblks_t
+xfs_rtbitmap_blockcount(
+	struct xfs_mount	*mp,
+	xfs_rtbxlen_t		rtextents)
+{
+	return howmany_64(rtextents, NBBY * mp->m_sb.sb_blocksize);
+}
+
+/*
+ * Compute the number of rtbitmap words needed to populate every block of a
+ * bitmap that is large enough to track the given number of rt extents.
+ */
+unsigned long long
+xfs_rtbitmap_wordcount(
+	struct xfs_mount	*mp,
+	xfs_rtbxlen_t		rtextents)
+{
+	xfs_filblks_t		blocks;
+
+	blocks = xfs_rtbitmap_blockcount(mp, rtextents);
+	return XFS_FSB_TO_B(mp, blocks) >> XFS_WORDLOG;
+}
diff --git a/libxfs/xfs_rtbitmap.h b/libxfs/xfs_rtbitmap.h
index 167ea6a08..618c96468 100644
--- a/libxfs/xfs_rtbitmap.h
+++ b/libxfs/xfs_rtbitmap.h
@@ -283,6 +283,11 @@ xfs_rtfree_extent(
 /* Same as above, but in units of rt blocks. */
 int xfs_rtfree_blocks(struct xfs_trans *tp, xfs_fsblock_t rtbno,
 		xfs_filblks_t rtlen);
+
+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);
 #else /* CONFIG_XFS_RT */
 # define xfs_rtfree_extent(t,b,l)			(-ENOSYS)
 # define xfs_rtfree_blocks(t,rb,rl)			(-ENOSYS)
@@ -290,6 +295,13 @@ int xfs_rtfree_blocks(struct xfs_trans *tp, xfs_fsblock_t rtbno,
 # define xfs_rtalloc_query_all(m,t,f,p)			(-ENOSYS)
 # define xfs_rtbuf_get(m,t,b,i,p)			(-ENOSYS)
 # define xfs_rtalloc_extent_is_free(m,t,s,l,i)		(-ENOSYS)
+static inline xfs_filblks_t
+xfs_rtbitmap_blockcount(struct xfs_mount *mp, xfs_rtbxlen_t rtextents)
+{
+	/* shut up gcc */
+	return 0;
+}
+# define xfs_rtbitmap_wordcount(mp, r)			(0)
 #endif /* CONFIG_XFS_RT */
 
 #endif /* __XFS_RTBITMAP_H__ */
diff --git a/libxfs/xfs_trans_resv.c b/libxfs/xfs_trans_resv.c
index 53c190b72..82b3d1522 100644
--- a/libxfs/xfs_trans_resv.c
+++ b/libxfs/xfs_trans_resv.c
@@ -217,11 +217,12 @@ xfs_rtalloc_block_count(
 	struct xfs_mount	*mp,
 	unsigned int		num_ops)
 {
-	unsigned int		blksz = XFS_FSB_TO_B(mp, 1);
-	unsigned int		rtbmp_bytes;
+	unsigned int		rtbmp_blocks;
+	xfs_rtxlen_t		rtxlen;
 
-	rtbmp_bytes = xfs_extlen_to_rtxlen(mp, XFS_MAX_BMBT_EXTLEN) / NBBY;
-	return (howmany(rtbmp_bytes, blksz) + 1) * num_ops;
+	rtxlen = xfs_extlen_to_rtxlen(mp, XFS_MAX_BMBT_EXTLEN);
+	rtbmp_blocks = xfs_rtbitmap_blockcount(mp, rtxlen);
+	return (rtbmp_blocks + 1) * num_ops;
 }
 
 /*
-- 
2.43.0