bcachefs: Kill bkey_buf in btree_path_down()

Allocate some (smaller) temporary storage in btree_trans for this -
btree_path_down() is in our max-stack call stack.

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

diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index b4bf421..6303531 100644 (file)
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -890,8 +890,7 @@ static noinline void btree_node_mem_ptr_set(struct btree_trans *trans,
 
 static noinline int btree_node_iter_and_journal_peek(struct btree_trans *trans,
                                                     struct btree_path *path,
-                                                    unsigned flags,
-                                                    struct bkey_buf *out)
+                                                    unsigned flags)
 {
        struct bch_fs *c = trans->c;
        struct btree_path_level *l = path_l(path);
@@ -915,7 +914,7 @@ static noinline int btree_node_iter_and_journal_peek(struct btree_trans *trans,
                goto err;
        }
 
-       bch2_bkey_buf_reassemble(out, c, k);
+       bkey_reassemble(&trans->btree_path_down, k);
 
        if ((flags & BTREE_ITER_prefetch) &&
            c->opts.btree_node_prefetch)
@@ -936,20 +935,17 @@ static __always_inline int btree_path_down(struct btree_trans *trans,
        struct btree *b;
        unsigned level = path->level - 1;
        enum six_lock_type lock_type = __btree_lock_want(path, level);
-       struct bkey_buf tmp;
        int ret;
 
        EBUG_ON(!btree_node_locked(path, path->level));
 
-       bch2_bkey_buf_init(&tmp);
-
        if (unlikely(trans->journal_replay_not_finished)) {
-               ret = btree_node_iter_and_journal_peek(trans, path, flags, &tmp);
+               ret = btree_node_iter_and_journal_peek(trans, path, flags);
                if (ret)
-                       goto err;
+                       return ret;
        } else {
                struct bkey_packed *k = bch2_btree_node_iter_peek(&l->iter, l->b);
-               if (!k) {
+               if (unlikely(!k)) {
                        struct printbuf buf = PRINTBUF;
 
                        prt_str(&buf, "node not found at pos ");
@@ -959,28 +955,28 @@ static __always_inline int btree_path_down(struct btree_trans *trans,
 
                        bch2_fs_fatal_error(c, "%s", buf.buf);
                        printbuf_exit(&buf);
-                       ret = -BCH_ERR_btree_need_topology_repair;
-                       goto err;
+                       return -BCH_ERR_btree_need_topology_repair;
                }
 
-               bch2_bkey_buf_unpack(&tmp, c, l->b, k);
+               bch2_bkey_unpack(l->b, &trans->btree_path_down, k);
 
-               if ((flags & BTREE_ITER_prefetch) &&
+               if (unlikely((flags & BTREE_ITER_prefetch)) &&
                    c->opts.btree_node_prefetch) {
                        ret = btree_path_prefetch(trans, path);
                        if (ret)
-                               goto err;
+                               return ret;
                }
        }
 
-       b = bch2_btree_node_get(trans, path, tmp.k, level, lock_type, trace_ip);
+       b = bch2_btree_node_get(trans, path, &trans->btree_path_down,
+                               level, lock_type, trace_ip);
        ret = PTR_ERR_OR_ZERO(b);
        if (unlikely(ret))
-               goto err;
+               return ret;
 
-       if (likely(!trans->journal_replay_not_finished &&
-                  tmp.k->k.type == KEY_TYPE_btree_ptr_v2) &&
-           unlikely(b != btree_node_mem_ptr(tmp.k)))
+       if (unlikely(b != btree_node_mem_ptr(&trans->btree_path_down)) &&
+           likely(!trans->journal_replay_not_finished &&
+                  trans->btree_path_down.k.type == KEY_TYPE_btree_ptr_v2))
                btree_node_mem_ptr_set(trans, path, level + 1, b);
 
        if (btree_node_read_locked(path, level + 1))
@@ -992,9 +988,7 @@ static __always_inline int btree_path_down(struct btree_trans *trans,
        bch2_btree_path_level_init(trans, path, b);
 
        bch2_btree_path_verify_locks(trans, path);
-err:
-       bch2_bkey_buf_exit(&tmp, c);
-       return ret;
+       return 0;
 }
 
 static int bch2_btree_path_traverse_all(struct btree_trans *trans)

diff --git a/fs/bcachefs/btree_types.h b/fs/bcachefs/btree_types.h
index 9d641bf..c61c417 100644 (file)
--- a/fs/bcachefs/btree_types.h
+++ b/fs/bcachefs/btree_types.h
@@ -555,6 +555,8 @@ struct btree_trans {
        unsigned                journal_u64s;
        unsigned                extra_disk_res; /* XXX kill */
 
+       __BKEY_PADDED(btree_path_down, BKEY_BTREE_PTR_VAL_U64s_MAX);
+
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
        struct lockdep_map      dep_map;
 #endif