bcachefs: Prep work for variable size btree node buffers

bcachefs btree nodes are big - typically 256k - and btree roots are
pinned in memory. As we're now up to 18 btrees, we now have significant
memory overhead in mostly empty btree roots.

And in the future we're going to start enforcing that certain btree node
boundaries exist, to solve lock contention issues - analagous to XFS's
AGIs.

Thus, we need to start allocating smaller btree node buffers when we
can. This patch changes code that refers to the filesystem constant
c->opts.btree_node_size to refer to the btree node buffer size -
btree_buf_bytes() - where appropriate.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 2 insertions, 3 deletions

diff --git a/fs/bcachefs/bset.c b/fs/bcachefs/bset.c
index 044fff9b2cf6..3fd1085b6c61 100644
--- a/fs/bcachefs/bset.c
+++ b/fs/bcachefs/bset.c
@@ -823,13 +823,12 @@ void bch2_bset_init_first(struct btree *b, struct bset *i)
 	set_btree_bset(b, t, i);
 }
 
-void bch2_bset_init_next(struct bch_fs *c, struct btree *b,
-			 struct btree_node_entry *bne)
+void bch2_bset_init_next(struct btree *b, struct btree_node_entry *bne)
 {
 	struct bset *i = &bne->keys;
 	struct bset_tree *t;
 
-	BUG_ON(bset_byte_offset(b, bne) >= btree_bytes(c));
+	BUG_ON(bset_byte_offset(b, bne) >= btree_buf_bytes(b));
 	BUG_ON((void *) bne < (void *) btree_bkey_last(b, bset_tree_last(b)));
 	BUG_ON(b->nsets >= MAX_BSETS);