xfs: encode the max btree height in the cursor

Encode the maximum btree height in the cursor, since we're soon going to
allow smaller cursors for AG btrees and larger cursors for file btrees.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

4 files changed, 10 insertions, 8 deletions

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 644b956301b6..2ae5bf9a74e7 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -239,7 +239,7 @@ xfs_bmap_get_bp(
 	if (!cur)
 		return NULL;
 
-	for (i = 0; i < XFS_BTREE_MAXLEVELS; i++) {
+	for (i = 0; i < cur->bc_maxlevels; i++) {
 		if (!cur->bc_levels[i].bp)
 			break;
 		if (xfs_buf_daddr(cur->bc_levels[i].bp) == bno)
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 25dfab81025f..6ced8f028d47 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -2933,7 +2933,7 @@ xfs_btree_new_iroot(
 	be16_add_cpu(&block->bb_level, 1);
 	xfs_btree_set_numrecs(block, 1);
 	cur->bc_nlevels++;
-	ASSERT(cur->bc_nlevels <= XFS_BTREE_MAXLEVELS);
+	ASSERT(cur->bc_nlevels <= cur->bc_maxlevels);
 	cur->bc_levels[level + 1].ptr = 1;
 
 	kp = xfs_btree_key_addr(cur, 1, block);
@@ -3097,7 +3097,7 @@ xfs_btree_new_root(
 	xfs_btree_setbuf(cur, cur->bc_nlevels, nbp);
 	cur->bc_levels[cur->bc_nlevels].ptr = nptr;
 	cur->bc_nlevels++;
-	ASSERT(cur->bc_nlevels <= XFS_BTREE_MAXLEVELS);
+	ASSERT(cur->bc_nlevels <= cur->bc_maxlevels);
 	*stat = 1;
 	return 0;
 error0:
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index 8e78ede87b16..ed0b7d5ab3a3 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -238,6 +238,7 @@ struct xfs_btree_cur
 	xfs_btnum_t		bc_btnum; /* identifies which btree type */
 	union xfs_btree_irec	bc_rec;	/* current insert/search record value */
 	uint8_t			bc_nlevels; /* number of levels in the tree */
+	uint8_t			bc_maxlevels; /* maximum levels for this btree type */
 	int			bc_statoff; /* offset of btree stats array */
 
 	/*
@@ -590,6 +591,7 @@ xfs_btree_alloc_cursor(
 	cur->bc_tp = tp;
 	cur->bc_mp = mp;
 	cur->bc_btnum = btnum;
+	cur->bc_maxlevels = XFS_BTREE_MAXLEVELS;
 
 	return cur;
 }
diff --git a/fs/xfs/libxfs/xfs_btree_staging.c b/fs/xfs/libxfs/xfs_btree_staging.c
index cc56efc2b90a..dd75e208b543 100644
--- a/fs/xfs/libxfs/xfs_btree_staging.c
+++ b/fs/xfs/libxfs/xfs_btree_staging.c
@@ -657,12 +657,12 @@ xfs_btree_bload_compute_geometry(
 	 * checking levels 0 and 1 here, so set bc_nlevels such that the btree
 	 * code doesn't interpret either as the root level.
 	 */
-	cur->bc_nlevels = XFS_BTREE_MAXLEVELS - 1;
+	cur->bc_nlevels = cur->bc_maxlevels - 1;
 	xfs_btree_bload_ensure_slack(cur, &bbl->leaf_slack, 0);
 	xfs_btree_bload_ensure_slack(cur, &bbl->node_slack, 1);
 
 	bbl->nr_records = nr_this_level = nr_records;
-	for (cur->bc_nlevels = 1; cur->bc_nlevels <= XFS_BTREE_MAXLEVELS;) {
+	for (cur->bc_nlevels = 1; cur->bc_nlevels <= cur->bc_maxlevels;) {
 		uint64_t	level_blocks;
 		uint64_t	dontcare64;
 		unsigned int	level = cur->bc_nlevels - 1;
@@ -703,7 +703,7 @@ xfs_btree_bload_compute_geometry(
 			 * block-based btree level.
 			 */
 			cur->bc_nlevels++;
-			ASSERT(cur->bc_nlevels <= XFS_BTREE_MAXLEVELS);
+			ASSERT(cur->bc_nlevels <= cur->bc_maxlevels);
 			xfs_btree_bload_level_geometry(cur, bbl, level,
 					nr_this_level, &avg_per_block,
 					&level_blocks, &dontcare64);
@@ -719,14 +719,14 @@ xfs_btree_bload_compute_geometry(
 
 			/* Otherwise, we need another level of btree. */
 			cur->bc_nlevels++;
-			ASSERT(cur->bc_nlevels <= XFS_BTREE_MAXLEVELS);
+			ASSERT(cur->bc_nlevels <= cur->bc_maxlevels);
 		}
 
 		nr_blocks += level_blocks;
 		nr_this_level = level_blocks;
 	}
 
-	if (cur->bc_nlevels > XFS_BTREE_MAXLEVELS)
+	if (cur->bc_nlevels > cur->bc_maxlevels)
 		return -EOVERFLOW;
 
 	bbl->btree_height = cur->bc_nlevels;