path: root/fs/xfs/libxfs/xfs_trans_resv.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
 * Copyright (C) 2010 Red Hat, Inc.
 * All Rights Reserved.
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_inode.h"
#include "xfs_bmap_btree.h"
#include "xfs_quota.h"
#include "xfs_trans.h"
#include "xfs_qm.h"
#include "xfs_trans_space.h"
#include "xfs_rtbitmap.h"
#include "xfs_attr_item.h"
#include "xfs_log.h"

#define _ALLOC	true
#define _FREE	false

/*
 * A buffer has a format structure overhead in the log in addition
 * to the data, so we need to take this into account when reserving
 * space in a transaction for a buffer.  Round the space required up
 * to a multiple of 128 bytes so that we don't change the historical
 * reservation that has been used for this overhead.
 */
STATIC uint
xfs_buf_log_overhead(void)
{
	return round_up(sizeof(struct xlog_op_header) +
			sizeof(struct xfs_buf_log_format), 128);
}

/*
 * Calculate out transaction log reservation per item in bytes.
 *
 * The nbufs argument is used to indicate the number of items that
 * will be changed in a transaction.  size is used to tell how many
 * bytes should be reserved per item.
 */
STATIC uint
xfs_calc_buf_res(
	uint		nbufs,
	uint		size)
{
	return nbufs * (size + xfs_buf_log_overhead());
}

/*
 * Per-extent log reservation for the btree changes involved in freeing or
 * allocating an extent.  In classic XFS there were two trees that will be
 * modified (bnobt + cntbt).  With rmap enabled, there are three trees
 * (rmapbt).  The number of blocks reserved is based on the formula:
 *
 * num trees * ((2 blocks/level * max depth) - 1)
 *
 * Keep in mind that max depth is calculated separately for each type of tree.
 */
uint
xfs_allocfree_block_count(
	struct xfs_mount *mp,
	uint		num_ops)
{
	uint		blocks;

	blocks = num_ops * 2 * (2 * mp->m_alloc_maxlevels - 1);
	if (xfs_has_rmapbt(mp))
		blocks += num_ops * (2 * mp->m_rmap_maxlevels - 1);

	return blocks;
}

/*
 * Per-extent log reservation for refcount btree changes.  These are never done
 * in the same transaction as an allocation or a free, so we compute them
 * separately.
 */
static unsigned int
xfs_refcountbt_block_count(
	struct xfs_mount	*mp,
	unsigned int		num_ops)
{
	return num_ops * (2 * mp->m_refc_maxlevels - 1);
}

static unsigned int
xfs_rtrefcountbt_block_count(
	struct xfs_mount	*mp,
	unsigned int		num_ops)
{
	return num_ops * (2 * mp->m_rtrefc_maxlevels - 1);
}

/*
 * Logging inodes is really tricksy. They are logged in memory format,
 * which means that what we write into the log doesn't directly translate into
 * the amount of space they use on disk.
 *
 * Case in point - btree format forks in memory format use more space than the
 * on-disk format. In memory, the buffer contains a normal btree block header so
 * the btree code can treat it as though it is just another generic buffer.
 * However, when we write it to the inode fork, we don't write all of this
 * header as it isn't needed. e.g. the root is only ever in the inode, so
 * there's no need for sibling pointers which would waste 16 bytes of space.
 *
 * Hence when we have an inode with a maximally sized btree format fork, then
 * amount of information we actually log is greater than the size of the inode
 * on disk. Hence we need an inode reservation function that calculates all this
 * correctly. So, we log:
 *
 * - 4 log op headers for object
 *	- for the ilf, the inode core and 2 forks
 * - inode log format object
 * - the inode core
 * - two inode forks containing bmap btree root blocks.
 *	- the btree data contained by both forks will fit into the inode size,
 *	  hence when combined with the inode core above, we have a total of the
 *	  actual inode size.
 *	- the BMBT headers need to be accounted separately, as they are
 *	  additional to the records and pointers that fit inside the inode
 *	  forks.
 */
STATIC uint
xfs_calc_inode_res(
	struct xfs_mount	*mp,
	uint			ninodes)
{
	return ninodes *
		(4 * sizeof(struct xlog_op_header) +
		 sizeof(struct xfs_inode_log_format) +
		 mp->m_sb.sb_inodesize +
		 2 * xfs_bmbt_block_len(mp));
}

/*
 * Inode btree record insertion/removal modifies the inode btree and free space
 * btrees (since the inobt does not use the agfl). This requires the following
 * reservation:
 *
 * the inode btree: max depth * blocksize
 * the allocation btrees: 2 trees * (max depth - 1) * block size
 *
 * The caller must account for SB and AG header modifications, etc.
 */
STATIC uint
xfs