[PATCH 11/14] xfs: dynamically allocate cursors based on maxlevels

Darrick J. Wong
2021-09-18T01:30:12Z

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

Replace the statically-sized btree cursor zone with dynamically sized
allocations so that we can reduce the memory overhead for per-AG bt
cursors while handling very tall btrees for rt metadata.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/libxfs/xfs_btree.c | 40 ++++++++++++++++++++++++++++++++--------
fs/xfs/libxfs/xfs_btree.h | 2 --
fs/xfs/xfs_super.c | 11 +----------
3 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 2486ba22c01d..f9516828a847 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -23,11 +23,6 @@
#include "xfs_btree_staging.h"
#include "xfs_ag.h"

-/*
- * Cursor allocation zone.
- */
-kmem_zone_t *xfs_btree_cur_zone;
-
/*
* Btree magic numbers.
*/
@@ -379,7 +374,7 @@ xfs_btree_del_cursor(
kmem_free(cur->bc_ops);
if (!(cur->bc_flags & XFS_BTREE_LONG_PTRS) && cur->bc_ag.pag)
xfs_perag_put(cur->bc_ag.pag);
- kmem_cache_free(xfs_btree_cur_zone, cur);
+ kmem_free(cur);
}

/*
@@ -4927,6 +4922,32 @@ 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
+xfs_btree_maxlevels(
+ struct xfs_mount *mp,
+ xfs_btnum_t btnum)
+{
+ switch (btnum) {
+ case XFS_BTNUM_BNO:
+ case XFS_BTNUM_CNT:
+ return mp->m_ag_maxlevels;
+ case XFS_BTNUM_BMAP:
+ return max(mp->m_bm_maxlevels[XFS_DATA_FORK],
+ mp->m_bm_maxlevels[XFS_ATTR_FORK]);
+ case XFS_BTNUM_INO:
+ case XFS_BTNUM_FINO:
+ return M_IGEO(mp)->inobt_maxlevels;
+ case XFS_BTNUM_RMAP:
+ return mp->m_rmap_maxlevels;
+ case XFS_BTNUM_REFC:
+ return mp->m_refc_maxlevels;
+ default:
+ ASSERT(0);
+ return XFS_BTREE_MAXLEVELS;
+ }
+}
+
/* Allocate a new btree cursor of the appropriate size. */
struct xfs_btree_cur *
xfs_btree_alloc_cursor(
@@ -4935,13 +4956,16 @@ xfs_btree_alloc_cursor(
xfs_btnum_t btnum)
{
struct xfs_btree_cur *cur;
+ unsigned int maxlevels = xfs_btree_maxlevels(mp, btnum);

- cur = kmem_cache_zalloc(xfs_btree_cur_zone, GFP_NOFS | __GFP_NOFAIL);
+ ASSERT(maxlevels <= XFS_BTREE_MAXLEVELS);
+
+ cur = kmem_zalloc(xfs_btree_cur_sizeof(maxlevels), KM_NOFS);
cur->bc_tp = tp;
cur->bc_mp = mp;
cur->bc_btnum = btnum;
cur->bc_blocklog = mp->m_sb.sb_blocklog;
- cur->bc_maxlevels = XFS_BTREE_MAXLEVELS;
+ cur->bc_maxlevels = maxlevels;

return cur;
}
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index 6075918efa0c..ae83fbf58c18 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -13,8 +13,6 @@ struct xfs_trans;
struct xfs_ifork;
struct xfs_perag;

-extern kmem_zone_t *xfs_btree_cur_zone;
-
/*
* Generic key, ptr and record wrapper structures.
*
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 30bae0657343..25a548bbb0b2 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1965,17 +1965,11 @@ xfs_init_zones(void)
if (!xfs_bmap_free_item_zone)
goto out_destroy_log_ticket_zone;

- xfs_btree_cur_zone = kmem_cache_create("xfs_btree_cur",
- xfs_btree_cur_sizeof(XFS_BTREE_MAXLEVELS),
- 0, 0, NULL);
- if (!xfs_btree_cur_zone)
- goto out_destroy_bmap_free_item_zone;
-
xfs_da_state_zone = kmem_cache_create("xfs_da_state",
sizeof(struct xfs_da_state),
0, 0, NULL);
if (!xfs_da_state_zone)
- goto out_destroy_btree_cur_zone;
+ goto out_destroy_bmap_free_item_zone;

xfs_ifork_zone = kmem_cache_create("xfs_ifork",
sizeof(struct xfs_ifork),
@@ -2105,8 +2099,6 @@ xfs_init_zones(void)
kmem_cache_destroy(xfs_ifork_zone);
out_destroy_da_state_zone:
kmem_cache_destroy(xfs_da_state_zone);
- out_destroy_btree_cur_zone:
- kmem_cache_destroy(xfs_btree_cur_zone);
out_destroy_bmap_free_item_zone:
kmem_cache_destroy(xfs_bmap_free_item_zone);
out_destroy_log_ticket_zone:
@@ -2138,7 +2130,6 @@ xfs_destroy_zones(void)
kmem_cache_destroy(xfs_trans_zone);
kmem_cache_destroy(xfs_ifork_zone);
kmem_cache_destroy(xfs_da_state_zone);
- kmem_cache_destroy(xfs_btree_cur_zone);
kmem_cache_destroy(xfs_bmap_free_item_zone);
kmem_cache_destroy(xfs_log_ticket_zone);
}