static int ext4_mb_pa_alloc(struct ext4_allocation_context *ac)
{
	struct ext4_prealloc_space *pa;

	BUG_ON(ext4_pspace_cachep == NULL);
	pa = kmem_cache_zalloc(ext4_pspace_cachep, GFP_NOFS);
	if (!pa)
		return -ENOMEM;
	atomic_set(&pa->pa_count, 1);
	ac->ac_pa = pa;
	return 0;
}
static int ext4_mb_pa_alloc(struct ext4_allocation_context *ac)
{
	struct ext4_prealloc_space *pa;

	BUG_ON(ext4_pspace_cachep == NULL);
	pa = kmem_cache_zalloc(ext4_pspace_cachep, GFP_NOFS);
	if (!pa)
		return -ENOMEM;
	atomic_set(&pa->pa_count, 1);
	ac->ac_pa = pa;
	return 0;
}