bcachefs: Use kvzalloc() when dynamically allocating btree paths

THis silences a mm/page_alloc.c warning about allocating more than a
page with GFP_NOFAIL - and there's no reason for this to not have a
vmalloc fallback anyways.

Signed-off-by: Kent Overstreet <[e-mail]>

fs/bcachefs/btree_iter.c

···
 {
 	unsigned nr = trans->nr_paths * 2;
 
-	void *p = kzalloc(BITS_TO_LONGS(nr) * sizeof(unsigned long) +
+	void *p = kvzalloc(BITS_TO_LONGS(nr) * sizeof(unsigned long) +
 			  sizeof(struct btree_trans_paths) +
 			  nr * sizeof(struct btree_path) +
 			  nr * sizeof(btree_path_idx_t) + 8 +
···
 	trans->paths		= NULL;
 
 	if (paths_allocated != trans->_paths_allocated)
-		kfree_rcu_mightsleep(paths_allocated);
+		kvfree_rcu_mightsleep(paths_allocated);
 
 	if (trans->mem_bytes == BTREE_TRANS_MEM_MAX)
 		mempool_free(trans->mem, &c->btree_trans_mem_pool);