[PATCH 1/9] xfs: store inode btree block counts in AGI header

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

Source kernel commit: 2a39946c984464e4aac82c556ba9915589be7323

Add a btree block usage counters for both inode btrees to the AGI header
so that we don't have to walk the entire finobt at mount time to create
the per-AG reservations.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 libxfs/xfs_ag.c           |    5 +++++
 libxfs/xfs_format.h       |   18 +++++++++++++++++-
 libxfs/xfs_ialloc.c       |    1 +
 libxfs/xfs_ialloc_btree.c |   21 +++++++++++++++++++++
 4 files changed, 44 insertions(+), 1 deletion(-)


diff --git a/libxfs/xfs_ag.c b/libxfs/xfs_ag.c
index ceaa7e5e4640..af8a0afdda93 100644
--- a/libxfs/xfs_ag.c
+++ b/libxfs/xfs_ag.c
@@ -333,6 +333,11 @@ xfs_agiblock_init(
 	}
 	for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++)
 		agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
+	if (xfs_sb_version_hasinobtcounts(&mp->m_sb)) {
+		agi->agi_iblocks = cpu_to_be32(1);
+		if (xfs_sb_version_hasfinobt(&mp->m_sb))
+			agi->agi_fblocks = cpu_to_be32(1);
+	}
 }
 
 typedef void (*aghdr_init_work_f)(struct xfs_mount *mp, struct xfs_buf *bp,
diff --git a/libxfs/xfs_format.h b/libxfs/xfs_format.h
index f0ecd064ff14..01544f9d5a57 100644
--- a/libxfs/xfs_format.h
+++ b/libxfs/xfs_format.h
@@ -449,6 +449,7 @@ xfs_sb_has_compat_feature(
 #define XFS_SB_FEAT_RO_COMPAT_FINOBT   (1 << 0)		/* free inode btree */
 #define XFS_SB_FEAT_RO_COMPAT_RMAPBT   (1 << 1)		/* reverse map btree */
 #define XFS_SB_FEAT_RO_COMPAT_REFLINK  (1 << 2)		/* reflinked files */
+#define XFS_SB_FEAT_RO_COMPAT_INOBTCNT (1 << 3)		/* inobt block counts */
 #define XFS_SB_FEAT_RO_COMPAT_ALL \
 		(XFS_SB_FEAT_RO_COMPAT_FINOBT | \
 		 XFS_SB_FEAT_RO_COMPAT_RMAPBT | \
@@ -563,6 +564,17 @@ static inline bool xfs_sb_version_hasreflink(struct xfs_sb *sbp)
 		(sbp->sb_features_ro_compat & XFS_SB_FEAT_RO_COMPAT_REFLINK);
 }
 
+/*
+ * Inode btree block counter.  We record the number of inobt and finobt blocks
+ * in the AGI header so that we can skip the finobt walk at mount time when
+ * setting up per-AG reservations.
+ */
+static inline bool xfs_sb_version_hasinobtcounts(struct xfs_sb *sbp)
+{
+	return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
+		(sbp->sb_features_ro_compat & XFS_SB_FEAT_RO_COMPAT_INOBTCNT);
+}
+
 /*
  * end of superblock version macros
  */
@@ -765,6 +777,9 @@ typedef struct xfs_agi {
 	__be32		agi_free_root; /* root of the free inode btree */
 	__be32		agi_free_level;/* levels in free inode btree */
 
+	__be32		agi_iblocks;	/* inobt blocks used */
+	__be32		agi_fblocks;	/* finobt blocks used */
+
 	/* structure must be padded to 64 bit alignment */
 } xfs_agi_t;
 
@@ -785,7 +800,8 @@ typedef struct xfs_agi {
 #define	XFS_AGI_ALL_BITS_R1	((1 << XFS_AGI_NUM_BITS_R1) - 1)
 #define	XFS_AGI_FREE_ROOT	(1 << 11)
 #define	XFS_AGI_FREE_LEVEL	(1 << 12)
-#define	XFS_AGI_NUM_BITS_R2	13
+#define	XFS_AGI_IBLOCKS		(1 << 13) /* both inobt/finobt block counters */
+#define	XFS_AGI_NUM_BITS_R2	14
 
 /* disk block (xfs_daddr_t) in the AG */
 #define XFS_AGI_DADDR(mp)	((xfs_daddr_t)(2 << (mp)->m_sectbb_log))
diff --git a/libxfs/xfs_ialloc.c b/libxfs/xfs_ialloc.c
index ce73feed981c..8adeb10e5d2e 100644
--- a/libxfs/xfs_ialloc.c
+++ b/libxfs/xfs_ialloc.c
@@ -2468,6 +2468,7 @@ xfs_ialloc_log_agi(
 		offsetof(xfs_agi_t, agi_unlinked),
 		offsetof(xfs_agi_t, agi_free_root),
 		offsetof(xfs_agi_t, agi_free_level),
+		offsetof(xfs_agi_t, agi_iblocks),
 		sizeof(xfs_agi_t)
 	};
 #ifdef DEBUG
diff --git a/libxfs/xfs_ialloc_btree.c b/libxfs/xfs_ialloc_btree.c
index 41c308c2e54c..3ed87d1c7251 100644
--- a/libxfs/xfs_ialloc_btree.c
+++ b/libxfs/xfs_ialloc_btree.c
@@ -66,6 +66,25 @@ xfs_finobt_set_root(
 			   XFS_AGI_FREE_ROOT | XFS_AGI_FREE_LEVEL);
 }
 
+/* Update the inode btree block counter for this btree. */
+static inline void
+xfs_inobt_mod_blockcount(
+	struct xfs_btree_cur	*cur,
+	int			howmuch)
+{
+	struct xfs_buf		*agbp = cur->bc_ag.agbp;
+	struct xfs_agi		*agi = agbp->b_addr;
+
+	if (!xfs_sb_version_hasinobtcounts(&cur->bc_mp->m_sb))
+		return;
+
+	if (cur->bc_btnum == XFS_BTNUM_FINO)
+		be32_add_cpu(&agi->agi_fblocks, howmuch);
+	else if (cur->bc_btnum == XFS_BTNUM_INO)
+		be32_add_cpu(&agi->agi_iblocks, howmuch);
+	xfs_ialloc_log_agi(cur->bc_tp, agbp, XFS_AGI_IBLOCKS);
+}
+
 STATIC int
 __xfs_inobt_alloc_block(
 	struct xfs_btree_cur	*cur,
@@ -101,6 +120,7 @@ __xfs_inobt_alloc_block(
 
 	new->s = cpu_to_be32(XFS_FSB_TO_AGBNO(args.mp, args.fsbno));
 	*stat = 1;
+	xfs_inobt_mod_blockcount(cur, 1);
 	return 0;
 }
 
@@ -133,6 +153,7 @@ __xfs_inobt_free_block(
 	struct xfs_buf		*bp,
 	enum xfs_ag_resv_type	resv)
 {
+	xfs_inobt_mod_blockcount(cur, -1);
 	return xfs_free_extent(cur->bc_tp,
 			XFS_DADDR_TO_FSB(cur->bc_mp, XFS_BUF_ADDR(bp)), 1,
 			&XFS_RMAP_OINFO_INOBT, resv);