ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
				struct ext4_allocation_request *ar, int *errp)
{
	struct ext4_allocation_context *ac = NULL;
	struct ext4_sb_info *sbi;
	struct super_block *sb;
	ext4_fsblk_t block = 0;
	unsigned int inquota = 0;
	unsigned int reserv_clstrs = 0;
	u64 seq;

	might_sleep();
	sb = ar->inode->i_sb;
	sbi = EXT4_SB(sb);

	trace_ext4_request_blocks(ar);

	/* Allow to use superuser reservation for quota file */
	if (ext4_is_quota_file(ar->inode))
		ar->flags |= EXT4_MB_USE_ROOT_BLOCKS;

	if ((ar->flags & EXT4_MB_DELALLOC_RESERVED) == 0) {
		/* Without delayed allocation we need to verify
		 * there is enough free blocks to do block allocation
		 * and verify allocation doesn't exceed the quota limits.
		 */
		while (ar->len &&
			ext4_claim_free_clusters(sbi, ar->len, ar->flags)) {

			/* let others to free the space */
			cond_resched();
			ar->len = ar->len >> 1;
		}
		if (!ar->len) {
			ext4_mb_show_pa(sb);
			*errp = -ENOSPC;
			return 0;
		}
		reserv_clstrs = ar->len;
		if (ar->flags & EXT4_MB_USE_ROOT_BLOCKS) {
			dquot_alloc_block_nofail(ar->inode,
						 EXT4_C2B(sbi, ar->len));
		} else {
			while (ar->len &&
				dquot_alloc_block(ar->inode,
						  EXT4_C2B(sbi, ar->len))) {

				ar->flags |= EXT4_MB_HINT_NOPREALLOC;
				ar->len--;
			}
		}
		inquota = ar->len;
		if (ar->len == 0) {
			*errp = -EDQUOT;
			goto out;
		}
	}

	ac = kmem_cache_zalloc(ext4_ac_cachep, GFP_NOFS);
	if (!ac) {
		ar->len = 0;
		*errp = -ENOMEM;
		goto out;
	}

	*errp = ext4_mb_initialize_context(ac, ar);
	if (*errp) {
		ar->len = 0;
		goto out;
	}

	ac->ac_op = EXT4_MB_HISTORY_PREALLOC;
	seq = this_cpu_read(discard_pa_seq);
	if (!ext4_mb_use_preallocated(ac)) {
		ac->ac_op = EXT4_MB_HISTORY_ALLOC;
		ext4_mb_normalize_request(ac, ar);

		*errp = ext4_mb_pa_alloc(ac);
		if (*errp)
			goto errout;
repeat:
		/* allocate space in core */
		*errp = ext4_mb_regular_allocator(ac);
		/*
		 * pa allocated above is added to grp->bb_prealloc_list only
		 * when we were able to allocate some block i.e. when
		 * ac->ac_status == AC_STATUS_FOUND.
		 * And error from above mean ac->ac_status != AC_STATUS_FOUND
		 * So we have to free this pa here itself.
		 */
		if (*errp) {
			ext4_mb_pa_free(ac);
			ext4_discard_allocated_blocks(ac);
			goto errout;
		}
		if (ac->ac_status == AC_STATUS_FOUND &&
			ac->ac_o_ex.fe_len >= ac->ac_f_ex.fe_len)
			ext4_mb_pa_free(ac);
	}
	if (likely(ac->ac_status == AC_STATUS_FOUND)) {
		*errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_clstrs);
		if (*errp) {
			ext4_discard_allocated_blocks(ac);
			goto errout;
		} else {
			block = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
			ar->len = ac->ac_b_ex.fe_len;
		}
	} else {
		if (ext4_mb_discard_preallocations_should_retry(sb, ac, &seq))
			goto repeat;
		/*
		 * If block allocation fails then the pa allocated above
		 * needs to be freed here itself.
		 */
		ext4_mb_pa_free(ac);
		*errp = -ENOSPC;
	}

errout:
	if (*errp) {
		ac->ac_b_ex.fe_len = 0;
		ar->len = 0;
		ext4_mb_show_ac(ac);
	}
	ext4_mb_release_context(ac);
out:
	if (ac)
		kmem_cache_free(ext4_ac_cachep, ac);
	if (inquota && ar->len < inquota)
		dquot_free_block(ar->inode, EXT4_C2B(sbi, inquota - ar->len));
	if (!ar->len) {
		if ((ar->flags & EXT4_MB_DELALLOC_RESERVED) == 0)
			/* release all the reserved blocks if non delalloc */
			percpu_counter_sub(&sbi->s_dirtyclusters_counter,
						reserv_clstrs);
	}

	trace_ext4_allocate_blocks(ar, (unsigned long long)block);

	return block;
}