[PATCH 7/8] xfs: hoist the node iroot update code out of xfs_btree_kill_iroot

Darrick J. Wong
2024-12-13T00:59:49Z

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

In preparation for allowing records in an inode btree root, hoist the
code that copies keyptrs from an existing node child into the root block
to a separate function. Remove some unnecessary conditionals and clean
up a few function calls in the new function. Note that this change
reorders the ->free_block call with respect to the change in bc_nlevels
to make it easier to support inode root leaf blocks in the next patch.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
fs/xfs/libxfs/xfs_btree.c | 84 +++++++++++++++++++++++++++++++--------------
1 file changed, 57 insertions(+), 27 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index ed09eeee916160..e83a8de5fb8746 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -3726,6 +3726,60 @@ xfs_btree_insert(
return error;
}

+/*
+ * Move the keyptrs from a child node block to the root block.
+ *
+ * Since the keyptr size does not change, all we have to do is increase the
+ * tree height, copy the keyptrs to the new internal node (cblock), shrink
+ * the root, and copy the pointers there.
+ */
+STATIC int
+xfs_btree_demote_node_child(
+ struct xfs_btree_cur *cur,
+ struct xfs_btree_block *cblock,
+ int level,
+ int numrecs)
+{
+ struct xfs_btree_block *block;
+ union xfs_btree_key *ckp;
+ union xfs_btree_key *kp;
+ union xfs_btree_ptr *cpp;
+ union xfs_btree_ptr *pp;
+ int i;
+ int error;
+
+ /*
+ * Adjust the root btree node size and the record count to match the
+ * doomed child so that we can copy the keyptrs ahead of changing the
+ * tree shape.
+ */
+ block = cur->bc_ops->broot_realloc(cur, numrecs);
+
+ xfs_btree_set_numrecs(block, numrecs);
+ ASSERT(block->bb_numrecs == cblock->bb_numrecs);
+
+ /* Copy keys from the doomed block. */
+ kp = xfs_btree_key_addr(cur, 1, block);
+ ckp = xfs_btree_key_addr(cur, 1, cblock);
+ xfs_btree_copy_keys(cur, kp, ckp, numrecs);
+
+ /* Copy pointers from the doomed block. */
+ pp = xfs_btree_ptr_addr(cur, 1, block);
+ cpp = xfs_btree_ptr_addr(cur, 1, cblock);
+ for (i = 0; i < numrecs; i++) {
+ error = xfs_btree_debug_check_ptr(cur, cpp, i, level - 1);
+ if (error)
+ return error;
+ }
+ xfs_btree_copy_ptrs(cur, pp, cpp, numrecs);
+
+ /* Decrease tree height, adjusting the root block level to match. */
+ cur->bc_levels[level - 1].bp = NULL;
+ be16_add_cpu(&block->bb_level, -1);
+ cur->bc_nlevels--;
+ return 0;
+}
+
/*
* Try to merge a non-leaf block back into the inode root.
*
@@ -3741,10 +3795,6 @@ xfs_btree_kill_iroot(
struct xfs_inode *ip = cur->bc_ino.ip;
struct xfs_btree_block *block;
struct xfs_btree_block *cblock;
- union xfs_btree_key *kp;
- union xfs_btree_key *ckp;
- union xfs_btree_ptr *pp;
- union xfs_btree_ptr *cpp;
struct xfs_buf *cbp;
int level;
int numrecs;
@@ -3752,7 +3802,6 @@ xfs_btree_kill_iroot(
#ifdef DEBUG
union xfs_btree_ptr ptr;
#endif
- int i;

ASSERT(cur->bc_ops->type == XFS_BTREE_TYPE_INODE);
ASSERT(cur->bc_nlevels > 1);
@@ -3792,35 +3841,16 @@ xfs_btree_kill_iroot(
ASSERT(xfs_btree_ptr_is_null(cur, &ptr));
#endif

- block = cur->bc_ops->broot_realloc(cur, numrecs);
-
- block->bb_numrecs = be16_to_cpu(numrecs);
- ASSERT(block->bb_numrecs == cblock->bb_numrecs);
-
- kp = xfs_btree_key_addr(cur, 1, block);
- ckp = xfs_btree_key_addr(cur, 1, cblock);
- xfs_btree_copy_keys(cur, kp, ckp, numrecs);
-
- pp = xfs_btree_ptr_addr(cur, 1, block);
- cpp = xfs_btree_ptr_addr(cur, 1, cblock);
-
- for (i = 0; i < numrecs; i++) {
- error = xfs_btree_debug_check_ptr(cur, cpp, i, level - 1);
- if (error)
- return error;
- }
-
- xfs_btree_copy_ptrs(cur, pp, cpp, numrecs);
+ error = xfs_btree_demote_node_child(cur, cblock, level, numrecs);
+ if (error)
+ return error;

error = xfs_btree_free_block(cur, cbp);
if (error)
return error;

- cur->bc_levels[level - 1].bp = NULL;
- be16_add_cpu(&block->bb_level, -1);
xfs_trans_log_inode(cur->bc_tp, ip,
XFS_ILOG_CORE | xfs_ilog_fbroot(cur->bc_ino.whichfork));
- cur->bc_nlevels--;
out0:
return 0;
}