xfs: add comments documenting the rebalance algorithm (3e27c418) · Commits · 戴 / test

fs/xfs/libxfs/xfs_iext_tree.c

+24 −0

Original line number	Diff line number	Diff line
		@@ -672,6 +672,11 @@ xfs_iext_rebalance_node(
		struct xfs_iext_node *node,
		int nr_entries)
		{
		/*
		* If the neighbouring nodes are completely full, or have different
		* parents, we might never be able to merge our node, and will only
		* delete it once the number of entries hits zero.
		*/
		if (nr_entries == 0)
		return node;

		@@ -693,6 +698,11 @@ xfs_iext_rebalance_node(
		int nr_next = xfs_iext_node_nr_entries(next, 0), i;

		if (nr_entries + nr_next <= KEYS_PER_NODE) {
		/*
		* Merge the next node into this node so that we don't
		* have to do an additional update of the keys in the
		* higher levels.
		*/
		for (i = 0; i < nr_next; i++) {
		node->keys[nr_entries + i] = next->keys[i];
		node->ptrs[nr_entries + i] = next->ptrs[i];
		@@ -741,6 +751,11 @@ again:
		return;

		if (level < ifp->if_height) {
		/*
		* If we aren't at the root yet try to find a neighbour node to
		* merge with (or delete the node if it is empty), and then
		* recurse up to the next level.
		*/
		level++;
		parent = xfs_iext_find_level(ifp, offset, level);
		pos = xfs_iext_node_pos(parent, offset);
		@@ -755,6 +770,10 @@ again:
		goto again;
		}
		} else if (nr_entries == 1) {
		/*
		* If we are at the root and only one entry is left we can just
		* free this node and update the root pointer.
		*/
		ASSERT(node == ifp->if_u1.if_root);
		ifp->if_u1.if_root = node->ptrs[0];
		ifp->if_height--;
		@@ -789,6 +808,11 @@ xfs_iext_rebalance_leaf(
		int nr_next = xfs_iext_leaf_nr_entries(ifp, leaf->next, 0), i;

		if (fill + nr_next <= RECS_PER_LEAF) {
		/*
		* Merge the next node into this node so that we don't
		* have to do an additional update of the keys in the
		* higher levels.
		*/
		for (i = 0; i < nr_next; i++)
		leaf->recs[fill + i] = leaf->next->recs[i];

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