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

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * Copyright (c) 2018 Red Hat, Inc.
 * All rights reserved.
 */

#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_rmap_btree.h"
#include "xfs_alloc.h"
#include "xfs_ialloc.h"
#include "xfs_rmap.h"
#include "xfs_ag.h"
#include "xfs_ag_resv.h"
#include "xfs_health.h"
#include "xfs_error.h"
#include "xfs_bmap.h"
#include "xfs_defer.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
#include "xfs_trace.h"
#include "xfs_inode.h"
#include "xfs_icache.h"


/*
 * Passive reference counting access wrappers to the perag structures.  If the
 * per-ag structure is to be freed, the freeing code is responsible for cleaning
 * up objects with passive references before freeing the structure. This is
 * things like cached buffers.
 */
struct xfs_perag *
xfs_perag_get(
	struct xfs_mount	*mp,
	xfs_agnumber_t		agno)
{
	struct xfs_perag	*pag;

	rcu_read_lock();
	pag = radix_tree_lookup(&mp->m_perag_tree, agno);
	if (pag) {
		trace_xfs_perag_get(pag, _RET_IP_);
		ASSERT(atomic_read(&pag->pag_ref) >= 0);
		atomic_inc(&pag->pag_ref);
	}
	rcu_read_unlock();
	return pag;
}

/*
 * search from @first to find the next perag with the given tag set.
 */
struct xfs_perag *
xfs_perag_get_tag(
	struct xfs_mount	*mp,
	xfs_agnumber_t		first,
	unsigned int		tag)
{
	struct xfs_perag	*pag;
	int			found;

	rcu_read_lock();
	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
					(void **)&pag, first, 1, tag);
	if (found <= 0) {
		rcu_read_unlock();
		return NULL;
	}
	trace_xfs_perag_get_tag(pag, _RET_IP_);
	atomic_inc(&pag->pag_ref);
	rcu_read_unlock();
	return pag;
}

/* Get a passive reference to the given perag. */
struct xfs_perag *
xfs_perag_hold(
	struct xfs_perag	*pag)
{
	ASSERT(atomic_read(&pag->pag_ref) > 0 ||
	       atomic_read(&pag->pag_active_ref) > 0);

	trace_xfs_perag_hold(pag, _RET_IP_);
	atomic_inc(&pag->pag_ref);
	return pag;
}

void
xfs_perag_put(
	struct xfs_perag	*pag)
{
	trace_xfs_perag_put(pag, _RET_IP_);
	ASSERT(atomic_read(&pag->pag_ref) > 0);
	atomic_dec(&pag->pag_ref);
}

/*
 * Active references for perag structures. This is for short term access to the
 * per ag structures for walking trees or accessing state. If an AG is being
 * shrunk or is offline, then this will fail to find that AG and return NULL
 * instead.
 */
struct xfs_perag *
xfs_perag_grab(
	struct xfs_mount	*mp,
	xfs_agnumber_t		agno)
{
	struct xfs_perag	*pag;

	rcu_read_lock();
	pag = radix_tree_lookup(&mp->m_perag_tree, agno);
	if (pag) {
		trace_xfs_perag_grab(pag, _RET_IP_);
		if (!atomic_inc_not_zero(&pag->pag_active_ref))
			pag = NULL;
	}
	rcu_read_unlock();
	return pag;
}

/*
 * search from @first to find the next perag with the given tag set.
 */
struct xfs_perag *
xfs_perag_grab_tag(
	struct xfs_mount	*mp,
	xfs_agnumber_t		first,
	int			tag)
{
	struct xfs_perag	*pag;
	int			found;

	rcu_read_lock();
	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
					(void **)&pag, first, 1, tag);
	if (found <= 0) {
		rcu_read_unlock();
		return NULL;
	}
	trace_xfs_perag_grab_tag(pag, _RET_IP_);
	if (!atomic_inc_not_zero(&pag->pag_active_ref))
		pag = NULL;
	rcu_read_unlock();
	return pag;
}

void
xfs_perag_rele(
	struct xfs_perag	*pag)
{
	trace_xfs_perag_rele(pag, _RET_IP_);
	if (atomic_dec_and_test(&pag->pag_active_ref))
		wake_up(&pag->pag_active_wq);
}

/*
 * xfs_initialize_perag_data
 *
 * Read in each per-ag structure so we can count up the number of
 * allocated inodes, free inodes and used filesystem blocks as this
 * information is no longer persistent in the superblock. Once we have
 * this information, write it into the in-core superblock structure.
 */
int
xfs_initialize_perag_data(
	struct xfs_mount	*mp,
	xfs_agnumber_t		agcount)
{
	xfs_agnumber_t		index;
	struct xfs_perag	*pag;
	struct xfs_sb		*sbp = &mp->m_sb;
	uint64_t		ifree = 0