[PATCH 12/14] xfs: compute actual maximum btree height for critical reservation calculation

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Compute the actual maximum btree height when deciding if per-AG block
reservation is critically low.  This only affects the sanity check
condition, since we /generally/ will trigger on the 10% threshold.
This is a long-winded way of saying that we're removing one more
usage of XFS_BTREE_MAXLEVELS.

Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
 fs/xfs/libxfs/xfs_ag_resv.c |    4 +++-
 fs/xfs/libxfs/xfs_btree.c   |   19 +++++++++++++++----
 fs/xfs/libxfs/xfs_btree.h   |    1 +
 3 files changed, 19 insertions(+), 5 deletions(-)


diff --git a/fs/xfs/libxfs/xfs_ag_resv.c b/fs/xfs/libxfs/xfs_ag_resv.c
index 2aa2b3484c28..931481fbdd72 100644
--- a/fs/xfs/libxfs/xfs_ag_resv.c
+++ b/fs/xfs/libxfs/xfs_ag_resv.c
@@ -72,6 +72,7 @@ xfs_ag_resv_critical(
 {
 	xfs_extlen_t			avail;
 	xfs_extlen_t			orig;
+	xfs_extlen_t			btree_maxlevels;
 
 	switch (type) {
 	case XFS_AG_RESV_METADATA:
@@ -91,7 +92,8 @@ xfs_ag_resv_critical(
 	trace_xfs_ag_resv_critical(pag, type, avail);
 
 	/* Critically low if less than 10% or max btree height remains. */
-	return XFS_TEST_ERROR(avail < orig / 10 || avail < XFS_BTREE_MAXLEVELS,
+	btree_maxlevels = xfs_btree_maxlevels(pag->pag_mount, XFS_BTNUM_MAX);
+	return XFS_TEST_ERROR(avail < orig / 10 || avail < btree_maxlevels,
 			pag->pag_mount, XFS_ERRTAG_AG_RESV_CRITICAL);
 }
 
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index f9516828a847..6cf49f7e1299 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -4922,12 +4922,17 @@ xfs_btree_has_more_records(
 		return block->bb_u.s.bb_rightsib != cpu_to_be32(NULLAGBLOCK);
 }
 
-/* Compute the maximum allowed height for a given btree type. */
-static unsigned int
+/*
+ * Compute the maximum allowed height for a given btree type.  If XFS_BTNUM_MAX
+ * is passed in, the maximum allowed height for all btree types is returned.
+ */
+unsigned int
 xfs_btree_maxlevels(
 	struct xfs_mount	*mp,
 	xfs_btnum_t		btnum)
 {
+	unsigned int		ret;
+
 	switch (btnum) {
 	case XFS_BTNUM_BNO:
 	case XFS_BTNUM_CNT:
@@ -4943,9 +4948,15 @@ xfs_btree_maxlevels(
 	case XFS_BTNUM_REFC:
 		return mp->m_refc_maxlevels;
 	default:
-		ASSERT(0);
-		return XFS_BTREE_MAXLEVELS;
+		break;
 	}
+
+	ret = mp->m_ag_maxlevels;
+	ret = max(ret, mp->m_bm_maxlevels[XFS_DATA_FORK]);
+	ret = max(ret, mp->m_bm_maxlevels[XFS_ATTR_FORK]);
+	ret = max(ret, M_IGEO(mp)->inobt_maxlevels);
+	ret = max(ret, mp->m_rmap_maxlevels);
+	return max(ret, mp->m_refc_maxlevels);
 }
 
 /* Allocate a new btree cursor of the appropriate size. */
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index ae83fbf58c18..106760c540c7 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -574,5 +574,6 @@ void xfs_btree_copy_keys(struct xfs_btree_cur *cur,
 		const union xfs_btree_key *src_key, int numkeys);
 struct xfs_btree_cur *xfs_btree_alloc_cursor(struct xfs_mount *mp,
 		struct xfs_trans *tp, xfs_btnum_t btnum);
+unsigned int xfs_btree_maxlevels(struct xfs_mount *mp, xfs_btnum_t btnum);
 
 #endif	/* __XFS_BTREE_H__ */