Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2016 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <darrick.wong@oracle.com>
 */
#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_alloc.h"
#include "xfs_errortag.h"
#include "xfs_error.h"
#include "xfs_trace.h"
#include "xfs_trans.h"
#include "xfs_rmap_btree.h"
#include "xfs_btree.h"
#include "xfs_refcount_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_sb.h"
#include "xfs_ag_resv.h"
 
/*
 * Per-AG Block Reservations
 *
 * For some kinds of allocation group metadata structures, it is advantageous
 * to reserve a small number of blocks in each AG so that future expansions of
 * that data structure do not encounter ENOSPC because errors during a btree
 * split cause the filesystem to go offline.
 *
 * Prior to the introduction of reflink, this wasn't an issue because the free
 * space btrees maintain a reserve of space (the AGFL) to handle any expansion
 * that may be necessary; and allocations of other metadata (inodes, BMBT,
 * dir/attr) aren't restricted to a single AG.  However, with reflink it is
 * possible to allocate all the space in an AG, have subsequent reflink/CoW
 * activity expand the refcount btree, and discover that there's no space left
 * to handle that expansion.  Since we can calculate the maximum size of the
 * refcount btree, we can reserve space for it and avoid ENOSPC.
 *
 * Handling per-AG reservations consists of three changes to the allocator's
 * behavior:  First, because these reservations are always needed, we decrease
 * the ag_max_usable counter to reflect the size of the AG after the reserved
 * blocks are taken.  Second, the reservations must be reflected in the
 * fdblocks count to maintain proper accounting.  Third, each AG must maintain
 * its own reserved block counter so that we can calculate the amount of space
 * that must remain free to maintain the reservations.  Fourth, the "remaining
 * reserved blocks" count must be used when calculating the length of the
 * longest free extent in an AG and to clamp maxlen in the per-AG allocation
 * functions.  In other words, we maintain a virtual allocation via in-core
 * accounting tricks so that we don't have to clean up after a crash. :)
 *
 * Reserved blocks can be managed by passing one of the enum xfs_ag_resv_type
 * values via struct xfs_alloc_arg or directly to the xfs_free_extent
 * function.  It might seem a little funny to maintain a reservoir of blocks
 * to feed another reservoir, but the AGFL only holds enough blocks to get
 * through the next transaction.  The per-AG reservation is to ensure (we
 * hope) that each AG never runs out of blocks.  Each data structure wanting
 * to use the reservation system should update ask/used in xfs_ag_resv_init.
 */
 
/*
 * Are we critically low on blocks?  For now we'll define that as the number
 * of blocks we can get our hands on being less than 10% of what we reserved
 * or less than some arbitrary number (maximum btree height).
 */
bool
xfs_ag_resv_critical(
<------>struct xfs_perag		*pag,
<------>enum xfs_ag_resv_type		type)
{
<------>xfs_extlen_t			avail;
<------>xfs_extlen_t			orig;
 
<------>switch (type) {
<------>case XFS_AG_RESV_METADATA:
<------><------>avail = pag->pagf_freeblks - pag->pag_rmapbt_resv.ar_reserved;
<------><------>orig = pag->pag_meta_resv.ar_asked;
<------><------>break;
<------>case XFS_AG_RESV_RMAPBT:
<------><------>avail = pag->pagf_freeblks + pag->pagf_flcount -
<------><------><------>pag->pag_meta_resv.ar_reserved;
<------><------>orig = pag->pag_rmapbt_resv.ar_asked;
<------><------>break;
<------>default:
<------><------>ASSERT(0);
<------><------>return false;
<------>}
 
<------>trace_xfs_ag_resv_critical(pag, type, avail);
 
<------>/* Critically low if less than 10% or max btree height remains. */
<------>return XFS_TEST_ERROR(avail < orig / 10 || avail < XFS_BTREE_MAXLEVELS,
<------><------><------>pag->pag_mount, XFS_ERRTAG_AG_RESV_CRITICAL);
}
 
/*
 * How many blocks are reserved but not used, and therefore must not be
 * allocated away?
 */
xfs_extlen_t
xfs_ag_resv_needed(
<------>struct xfs_perag		*pag,
<------>enum xfs_ag_resv_type		type)
{
<------>xfs_extlen_t			len;
 
<------>len = pag->pag_meta_resv.ar_reserved + pag->pag_rmapbt_resv.ar_reserved;
<------>switch (type) {
<------>case XFS_AG_RESV_METADATA:
<------>case XFS_AG_RESV_RMAPBT:
<------><------>len -= xfs_perag_resv(pag, type)->ar_reserved;
<------><------>break;
<------>case XFS_AG_RESV_NONE:
<------><------>/* empty */
<------><------>break;
<------>default:
<------><------>ASSERT(0);
<------>}
 
<------>trace_xfs_ag_resv_needed(pag, type, len);
 
<------>return len;
}
 
/* Clean out a reservation */
static int
__xfs_ag_resv_free(
<------>struct xfs_perag		*pag,
<------>enum xfs_ag_resv_type		type)
{
<------>struct xfs_ag_resv		*resv;
<------>xfs_extlen_t			oldresv;
<------>int				error;
 
<------>trace_xfs_ag_resv_free(pag, type, 0);
 
<------>resv = xfs_perag_resv(pag, type);
<------>if (pag->pag_agno == 0)
<------><------>pag->pag_mount->m_ag_max_usable += resv->ar_asked;
<------>/*
<------> * RMAPBT blocks come from the AGFL and AGFL blocks are always
<------> * considered "free", so whatever was reserved at mount time must be
<------> * given back at umount.
<------> */
<------>if (type == XFS_AG_RESV_RMAPBT)
<------><------>oldresv = resv->ar_orig_reserved;
<------>else
<------><------>oldresv = resv->ar_reserved;
<------>error = xfs_mod_fdblocks(pag->pag_mount, oldresv, true);
<------>resv->ar_reserved = 0;
<------>resv->ar_asked = 0;
<------>resv->ar_orig_reserved = 0;
 
<------>if (error)
<------><------>trace_xfs_ag_resv_free_error(pag->pag_mount, pag->pag_agno,
<------><------><------><------>error, _RET_IP_);
<------>return error;
}
 
/* Free a per-AG reservation. */
int
xfs_ag_resv_free(
<------>struct xfs_perag		*pag)
{
<------>int				error;
<------>int				err2;
 
<------>error = __xfs_ag_resv_free(pag, XFS_AG_RESV_RMAPBT);
<------>err2 = __xfs_ag_resv_free(pag, XFS_AG_RESV_METADATA);
<------>if (err2 && !error)
<------><------>error = err2;
<------>return error;
}
 
static int
__xfs_ag_resv_init(
<------>struct xfs_perag		*pag,
<------>enum xfs_ag_resv_type		type,
<------>xfs_extlen_t			ask,
<------>xfs_extlen_t			used)
{
<------>struct xfs_mount		*mp = pag->pag_mount;
<------>struct xfs_ag_resv		*resv;
<------>int				error;
<------>xfs_extlen_t			hidden_space;
 
<------>if (used > ask)
<------><------>ask = used;
 
<------>switch (type) {
<------>case XFS_AG_RESV_RMAPBT:
<------><------>/*
<------><------> * Space taken by the rmapbt is not subtracted from fdblocks
<------><------> * because the rmapbt lives in the free space.  Here we must
<------><------> * subtract the entire reservation from fdblocks so that we
<------><------> * always have blocks available for rmapbt expansion.
<------><------> */
<------><------>hidden_space = ask;
<------><------>break;
<------>case XFS_AG_RESV_METADATA:
<------><------>/*
<------><------> * Space taken by all other metadata btrees are accounted
<------><------> * on-disk as used space.  We therefore only hide the space
<------><------> * that is reserved but not used by the trees.
<------><------> */
<------><------>hidden_space = ask - used;
<------><------>break;
<------>default:
<------><------>ASSERT(0);
<------><------>return -EINVAL;
<------>}
<------>error = xfs_mod_fdblocks(mp, -(int64_t)hidden_space, true);
<------>if (error) {
<------><------>trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno,
<------><------><------><------>error, _RET_IP_);
<------><------>xfs_warn(mp,
"Per-AG reservation for AG %u failed.  Filesystem may run out of space.",
<------><------><------><------>pag->pag_agno);
<------><------>return error;
<------>}
 
<------>/*
<------> * Reduce the maximum per-AG allocation length by however much we're
<------> * trying to reserve for an AG.  Since this is a filesystem-wide
<------> * counter, we only make the adjustment for AG 0.  This assumes that
<------> * there aren't any AGs hungrier for per-AG reservation than AG 0.
<------> */
<------>if (pag->pag_agno == 0)
<------><------>mp->m_ag_max_usable -= ask;
 
<------>resv = xfs_perag_resv(pag, type);
<------>resv->ar_asked = ask;
<------>resv->ar_orig_reserved = hidden_space;
<------>resv->ar_reserved = ask - used;
 
<------>trace_xfs_ag_resv_init(pag, type, ask);
<------>return 0;
}
 
/* Create a per-AG block reservation. */
int
xfs_ag_resv_init(
<------>struct xfs_perag		*pag,
<------>struct xfs_trans		*tp)
{
<------>struct xfs_mount		*mp = pag->pag_mount;
<------>xfs_agnumber_t			agno = pag->pag_agno;
<------>xfs_extlen_t			ask;
<------>xfs_extlen_t			used;
<------>int				error = 0;
 
<------>/* Create the metadata reservation. */
<------>if (pag->pag_meta_resv.ar_asked == 0) {
<------><------>ask = used = 0;
 
<------><------>error = xfs_refcountbt_calc_reserves(mp, tp, agno, &ask, &used);
<------><------>if (error)
<------><------><------>goto out;
 
<------><------>error = xfs_finobt_calc_reserves(mp, tp, agno, &ask, &used);
<------><------>if (error)
<------><------><------>goto out;
 
<------><------>error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
<------><------><------><------>ask, used);
<------><------>if (error) {
<------><------><------>/*
<------><------><------> * Because we didn't have per-AG reservations when the
<------><------><------> * finobt feature was added we might not be able to
<------><------><------> * reserve all needed blocks.  Warn and fall back to the
<------><------><------> * old and potentially buggy code in that case, but
<------><------><------> * ensure we do have the reservation for the refcountbt.
<------><------><------> */
<------><------><------>ask = used = 0;
 
<------><------><------>mp->m_finobt_nores = true;
 
<------><------><------>error = xfs_refcountbt_calc_reserves(mp, tp, agno, &ask,
<------><------><------><------><------>&used);
<------><------><------>if (error)
<------><------><------><------>goto out;
 
<------><------><------>error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
<------><------><------><------><------>ask, used);
<------><------><------>if (error)
<------><------><------><------>goto out;
<------><------>}
<------>}
 
<------>/* Create the RMAPBT metadata reservation */
<------>if (pag->pag_rmapbt_resv.ar_asked == 0) {
<------><------>ask = used = 0;
 
<------><------>error = xfs_rmapbt_calc_reserves(mp, tp, agno, &ask, &used);
<------><------>if (error)
<------><------><------>goto out;
 
<------><------>error = __xfs_ag_resv_init(pag, XFS_AG_RESV_RMAPBT, ask, used);
<------><------>if (error)
<------><------><------>goto out;
<------>}
 
#ifdef DEBUG
<------>/* need to read in the AGF for the ASSERT below to work */
<------>error = xfs_alloc_pagf_init(pag->pag_mount, tp, pag->pag_agno, 0);
<------>if (error)
<------><------>return error;
 
<------>ASSERT(xfs_perag_resv(pag, XFS_AG_RESV_METADATA)->ar_reserved +
<------>       xfs_perag_resv(pag, XFS_AG_RESV_RMAPBT)->ar_reserved <=
<------>       pag->pagf_freeblks + pag->pagf_flcount);
#endif
out:
<------>return error;
}
 
/* Allocate a block from the reservation. */
void
xfs_ag_resv_alloc_extent(
<------>struct xfs_perag		*pag,
<------>enum xfs_ag_resv_type		type,
<------>struct xfs_alloc_arg		*args)
{
<------>struct xfs_ag_resv		*resv;
<------>xfs_extlen_t			len;
<------>uint				field;
 
<------>trace_xfs_ag_resv_alloc_extent(pag, type, args->len);
 
<------>switch (type) {
<------>case XFS_AG_RESV_AGFL:
<------><------>return;
<------>case XFS_AG_RESV_METADATA:
<------>case XFS_AG_RESV_RMAPBT:
<------><------>resv = xfs_perag_resv(pag, type);
<------><------>break;
<------>default:
<------><------>ASSERT(0);
<------><------>/* fall through */
<------>case XFS_AG_RESV_NONE:
<------><------>field = args->wasdel ? XFS_TRANS_SB_RES_FDBLOCKS :
<------><------><------><------>       XFS_TRANS_SB_FDBLOCKS;
<------><------>xfs_trans_mod_sb(args->tp, field, -(int64_t)args->len);
<------><------>return;
<------>}
 
<------>len = min_t(xfs_extlen_t, args->len, resv->ar_reserved);
<------>resv->ar_reserved -= len;
<------>if (type == XFS_AG_RESV_RMAPBT)
<------><------>return;
<------>/* Allocations of reserved blocks only need on-disk sb updates... */
<------>xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_RES_FDBLOCKS, -(int64_t)len);
<------>/* ...but non-reserved blocks need in-core and on-disk updates. */
<------>if (args->len > len)
<------><------>xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_FDBLOCKS,
<------><------><------><------>-((int64_t)args->len - len));
}
 
/* Free a block to the reservation. */
void
xfs_ag_resv_free_extent(
<------>struct xfs_perag		*pag,
<------>enum xfs_ag_resv_type		type,
<------>struct xfs_trans		*tp,
<------>xfs_extlen_t			len)
{
<------>xfs_extlen_t			leftover;
<------>struct xfs_ag_resv		*resv;
 
<------>trace_xfs_ag_resv_free_extent(pag, type, len);
 
<------>switch (type) {
<------>case XFS_AG_RESV_AGFL:
<------><------>return;
<------>case XFS_AG_RESV_METADATA:
<------>case XFS_AG_RESV_RMAPBT:
<------><------>resv = xfs_perag_resv(pag, type);
<------><------>break;
<------>default:
<------><------>ASSERT(0);
<------><------>/* fall through */
<------>case XFS_AG_RESV_NONE:
<------><------>xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (int64_t)len);
<------><------>return;
<------>}
 
<------>leftover = min_t(xfs_extlen_t, len, resv->ar_asked - resv->ar_reserved);
<------>resv->ar_reserved += leftover;
<------>if (type == XFS_AG_RESV_RMAPBT)
<------><------>return;
<------>/* Freeing into the reserved pool only requires on-disk update... */
<------>xfs_trans_mod_sb(tp, XFS_TRANS_SB_RES_FDBLOCKS, len);
<------>/* ...but freeing beyond that requires in-core and on-disk update. */
<------>if (len > leftover)
<------><------>xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, len - leftover);
}