[thirdparty/xfsprogs-dev.git] / libxfs / xfs_ag_resv.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2016 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <darrick.wong@oracle.com>
 */
#include "libxfs_priv.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_sb.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_alloc.h"
#include "xfs_errortag.h"
#include "xfs_trace.h"
#include "xfs_cksum.h"
#include "xfs_trans.h"
#include "xfs_bit.h"
#include "xfs_bmap.h"
#include "xfs_bmap_btree.h"
#include "xfs_ag_resv.h"
#include "xfs_trans_space.h"
#include "xfs_rmap_btree.h"
#include "xfs_btree.h"
#include "xfs_refcount_btree.h"
#include "xfs_ialloc_btree.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_inotbt_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);
}
Commit	Line	Data
37b3b4d6	1	// SPDX-License-Identifier: GPL-2.0+
cf8ce220 DW	2	/*
cf8ce220 DW	3	* Copyright (C) 2016 Oracle. All Rights Reserved.
cf8ce220	4	* Author: Darrick J. Wong <darrick.wong@oracle.com>
cf8ce220 DW	5	*/
	6	#include "libxfs_priv.h"
	7	#include "xfs_fs.h"
	8	#include "xfs_shared.h"
	9	#include "xfs_format.h"
	10	#include "xfs_log_format.h"
	11	#include "xfs_trans_resv.h"
	12	#include "xfs_sb.h"
	13	#include "xfs_mount.h"
	14	#include "xfs_defer.h"
	15	#include "xfs_alloc.h"
56d3fc2b	16	#include "xfs_errortag.h"
cf8ce220 DW	17	#include "xfs_trace.h"
	18	#include "xfs_cksum.h"
	19	#include "xfs_trans.h"
	20	#include "xfs_bit.h"
	21	#include "xfs_bmap.h"
	22	#include "xfs_bmap_btree.h"
	23	#include "xfs_ag_resv.h"
	24	#include "xfs_trans_space.h"
	25	#include "xfs_rmap_btree.h"
	26	#include "xfs_btree.h"
02cc8b2a	27	#include "xfs_refcount_btree.h"
74e502ac	28	#include "xfs_ialloc_btree.h"
cf8ce220 DW	29
	30	/*
	31	* Per-AG Block Reservations
	32	*
	33	* For some kinds of allocation group metadata structures, it is advantageous
	34	* to reserve a small number of blocks in each AG so that future expansions of
	35	* that data structure do not encounter ENOSPC because errors during a btree
	36	* split cause the filesystem to go offline.
	37	*
	38	* Prior to the introduction of reflink, this wasn't an issue because the free
	39	* space btrees maintain a reserve of space (the AGFL) to handle any expansion
	40	* that may be necessary; and allocations of other metadata (inodes, BMBT,
	41	* dir/attr) aren't restricted to a single AG. However, with reflink it is
	42	* possible to allocate all the space in an AG, have subsequent reflink/CoW
	43	* activity expand the refcount btree, and discover that there's no space left
	44	* to handle that expansion. Since we can calculate the maximum size of the
	45	* refcount btree, we can reserve space for it and avoid ENOSPC.
	46	*
	47	* Handling per-AG reservations consists of three changes to the allocator's
	48	* behavior: First, because these reservations are always needed, we decrease
	49	* the ag_max_usable counter to reflect the size of the AG after the reserved
	50	* blocks are taken. Second, the reservations must be reflected in the
	51	* fdblocks count to maintain proper accounting. Third, each AG must maintain
	52	* its own reserved block counter so that we can calculate the amount of space
	53	* that must remain free to maintain the reservations. Fourth, the "remaining
	54	* reserved blocks" count must be used when calculating the length of the
	55	* longest free extent in an AG and to clamp maxlen in the per-AG allocation
	56	* functions. In other words, we maintain a virtual allocation via in-core
	57	* accounting tricks so that we don't have to clean up after a crash. :)
	58	*
	59	* Reserved blocks can be managed by passing one of the enum xfs_ag_resv_type
	60	* values via struct xfs_alloc_arg or directly to the xfs_free_extent
	61	* function. It might seem a little funny to maintain a reservoir of blocks
	62	* to feed another reservoir, but the AGFL only holds enough blocks to get
	63	* through the next transaction. The per-AG reservation is to ensure (we
	64	* hope) that each AG never runs out of blocks. Each data structure wanting
	65	* to use the reservation system should update ask/used in xfs_ag_resv_init.
	66	*/
	67
	68	/*
	69	* Are we critically low on blocks? For now we'll define that as the number
	70	* of blocks we can get our hands on being less than 10% of what we reserved
	71	* or less than some arbitrary number (maximum btree height).
	72	*/
	73	bool
	74	xfs_ag_resv_critical(
	75	struct xfs_perag *pag,
	76	enum xfs_ag_resv_type type)
	77	{
	78	xfs_extlen_t avail;
	79	xfs_extlen_t orig;
	80
	81	switch (type) {
	82	case XFS_AG_RESV_METADATA:
65a15e06	83	avail = pag->pagf_freeblks - pag->pag_rmapbt_resv.ar_reserved;
cf8ce220 DW	84	orig = pag->pag_meta_resv.ar_asked;
cf8ce220 DW	85	break;
65a15e06	86	case XFS_AG_RESV_RMAPBT:
cf8ce220 DW	87	avail = pag->pagf_freeblks + pag->pagf_flcount -
cf8ce220 DW	88	pag->pag_meta_resv.ar_reserved;
65a15e06	89	orig = pag->pag_rmapbt_resv.ar_asked;
cf8ce220 DW	90	break;
	91	default:
	92	ASSERT(0);
	93	return false;
	94	}
	95
	96	trace_xfs_ag_resv_critical(pag, type, avail);
	97
	98	/* Critically low if less than 10% or max btree height remains. */
c7bf1398	99	return XFS_TEST_ERROR(avail < orig / 10 \|\| avail < XFS_BTREE_MAXLEVELS,
e2a190dd	100	pag->pag_mount, XFS_ERRTAG_AG_RESV_CRITICAL);
cf8ce220 DW	101	}
	102
	103	/*
	104	* How many blocks are reserved but not used, and therefore must not be
	105	* allocated away?
	106	*/
	107	xfs_extlen_t
	108	xfs_ag_resv_needed(
	109	struct xfs_perag *pag,
	110	enum xfs_ag_resv_type type)
	111	{
	112	xfs_extlen_t len;
	113
65a15e06	114	len = pag->pag_meta_resv.ar_reserved + pag->pag_rmapbt_resv.ar_reserved;
cf8ce220 DW	115	switch (type) {
cf8ce220 DW	116	case XFS_AG_RESV_METADATA:
65a15e06	117	case XFS_AG_RESV_RMAPBT:
cf8ce220 DW	118	len -= xfs_perag_resv(pag, type)->ar_reserved;
	119	break;
	120	case XFS_AG_RESV_NONE:
	121	/* empty */
	122	break;
	123	default:
	124	ASSERT(0);
	125	}
	126
	127	trace_xfs_ag_resv_needed(pag, type, len);
	128
	129	return len;
	130	}
	131
	132	/* Clean out a reservation */
	133	static int
	134	__xfs_ag_resv_free(
	135	struct xfs_perag *pag,
	136	enum xfs_ag_resv_type type)
	137	{
	138	struct xfs_ag_resv *resv;
	139	xfs_extlen_t oldresv;
	140	int error;
	141
	142	trace_xfs_ag_resv_free(pag, type, 0);
	143
	144	resv = xfs_perag_resv(pag, type);
8b068926 DW	145	if (pag->pag_agno == 0)
8b068926 DW	146	pag->pag_mount->m_ag_max_usable += resv->ar_asked;
cf8ce220	147	/*
65a15e06 BF	148	* RMAPBT blocks come from the AGFL and AGFL blocks are always
	149	* considered "free", so whatever was reserved at mount time must be
	150	* given back at umount.
cf8ce220	151	*/
65a15e06	152	if (type == XFS_AG_RESV_RMAPBT)
cf8ce220 DW	153	oldresv = resv->ar_orig_reserved;
	154	else
	155	oldresv = resv->ar_reserved;
	156	error = xfs_mod_fdblocks(pag->pag_mount, oldresv, true);
	157	resv->ar_reserved = 0;
	158	resv->ar_asked = 0;
2d49506d	159	resv->ar_orig_reserved = 0;
cf8ce220 DW	160
	161	if (error)
	162	trace_xfs_ag_resv_free_error(pag->pag_mount, pag->pag_agno,
	163	error, _RET_IP_);
	164	return error;
	165	}
	166
	167	/* Free a per-AG reservation. */
	168	int
	169	xfs_ag_resv_free(
	170	struct xfs_perag *pag)
	171	{
	172	int error;
	173	int err2;
	174
65a15e06	175	error = __xfs_ag_resv_free(pag, XFS_AG_RESV_RMAPBT);
cf8ce220 DW	176	err2 = __xfs_ag_resv_free(pag, XFS_AG_RESV_METADATA);
	177	if (err2 && !error)
	178	error = err2;
	179	return error;
	180	}
	181
	182	static int
	183	__xfs_ag_resv_init(
	184	struct xfs_perag *pag,
	185	enum xfs_ag_resv_type type,
	186	xfs_extlen_t ask,
	187	xfs_extlen_t used)
	188	{
	189	struct xfs_mount *mp = pag->pag_mount;
	190	struct xfs_ag_resv *resv;
	191	int error;
2d49506d	192	xfs_extlen_t hidden_space;
cf8ce220	193
cf8ce220 DW	194	if (used > ask)
cf8ce220 DW	195	ask = used;
cf8ce220	196
2d49506d DW	197	switch (type) {
	198	case XFS_AG_RESV_RMAPBT:
	199	/*
	200	* Space taken by the rmapbt is not subtracted from fdblocks
	201	* because the rmapbt lives in the free space. Here we must
	202	* subtract the entire reservation from fdblocks so that we
	203	* always have blocks available for rmapbt expansion.
	204	*/
	205	hidden_space = ask;
	206	break;
	207	case XFS_AG_RESV_METADATA:
	208	/*
	209	* Space taken by all other metadata btrees are accounted
	210	* on-disk as used space. We therefore only hide the space
	211	* that is reserved but not used by the trees.
	212	*/
	213	hidden_space = ask - used;
	214	break;
	215	default:
	216	ASSERT(0);
	217	return -EINVAL;
	218	}
	219	error = xfs_mod_fdblocks(mp, -(int64_t)hidden_space, true);
2ffa676f	220	if (error) {
cf8ce220 DW	221	trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno,
cf8ce220 DW	222	error, _RET_IP_);
74e502ac CH	223	xfs_warn(mp,
	224	"Per-AG reservation for AG %u failed. Filesystem may run out of space.",
	225	pag->pag_agno);
2ffa676f CH	226	return error;
2ffa676f CH	227	}
cf8ce220	228
8b068926 DW	229	/*
	230	* Reduce the maximum per-AG allocation length by however much we're
	231	* trying to reserve for an AG. Since this is a filesystem-wide
	232	* counter, we only make the adjustment for AG 0. This assumes that
	233	* there aren't any AGs hungrier for per-AG reservation than AG 0.
	234	*/
	235	if (pag->pag_agno == 0)
	236	mp->m_ag_max_usable -= ask;
2ffa676f CH	237
	238	resv = xfs_perag_resv(pag, type);
	239	resv->ar_asked = ask;
2d49506d DW	240	resv->ar_orig_reserved = hidden_space;
2d49506d DW	241	resv->ar_reserved = ask - used;
2ffa676f CH	242
	243	trace_xfs_ag_resv_init(pag, type, ask);
	244	return 0;
cf8ce220 DW	245	}
	246
	247	/* Create a per-AG block reservation. */
	248	int
	249	xfs_ag_resv_init(
0d802327 DW	250	struct xfs_perag *pag,
0d802327 DW	251	struct xfs_trans *tp)
cf8ce220	252	{
74e502ac CH	253	struct xfs_mount *mp = pag->pag_mount;
74e502ac CH	254	xfs_agnumber_t agno = pag->pag_agno;
cf8ce220 DW	255	xfs_extlen_t ask;
	256	xfs_extlen_t used;
	257	int error = 0;
	258
	259	/* Create the metadata reservation. */
	260	if (pag->pag_meta_resv.ar_asked == 0) {
	261	ask = used = 0;
	262
0d802327	263	error = xfs_refcountbt_calc_reserves(mp, tp, agno, &ask, &used);
02cc8b2a DW	264	if (error)
	265	goto out;
	266
0d802327	267	error = xfs_finobt_calc_reserves(mp, tp, agno, &ask, &used);
cf8ce220 DW	268	if (error)
cf8ce220 DW	269	goto out;
74e502ac CH	270
	271	error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
	272	ask, used);
	273	if (error) {
	274	/*
	275	* Because we didn't have per-AG reservations when the
	276	* finobt feature was added we might not be able to
	277	* reserve all needed blocks. Warn and fall back to the
	278	* old and potentially buggy code in that case, but
	279	* ensure we do have the reservation for the refcountbt.
	280	*/
	281	ask = used = 0;
	282
	283	mp->m_inotbt_nores = true;
	284
0d802327	285	error = xfs_refcountbt_calc_reserves(mp, tp, agno, &ask,
74e502ac CH	286	&used);
	287	if (error)
	288	goto out;
	289
	290	error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
	291	ask, used);
	292	if (error)
	293	goto out;
	294	}
cf8ce220 DW	295	}
cf8ce220 DW	296
65a15e06 BF	297	/* Create the RMAPBT metadata reservation */
65a15e06 BF	298	if (pag->pag_rmapbt_resv.ar_asked == 0) {
cf8ce220 DW	299	ask = used = 0;
cf8ce220 DW	300
0d802327	301	error = xfs_rmapbt_calc_reserves(mp, tp, agno, &ask, &used);
02cc8b2a DW	302	if (error)
	303	goto out;
	304
65a15e06	305	error = __xfs_ag_resv_init(pag, XFS_AG_RESV_RMAPBT, ask, used);
cf8ce220 DW	306	if (error)
	307	goto out;
	308	}
	309
74e502ac CH	310	#ifdef DEBUG
74e502ac CH	311	/* need to read in the AGF for the ASSERT below to work */
0d802327	312	error = xfs_alloc_pagf_init(pag->pag_mount, tp, pag->pag_agno, 0);
74e502ac CH	313	if (error)
	314	return error;
	315
f21c57ed	316	ASSERT(xfs_perag_resv(pag, XFS_AG_RESV_METADATA)->ar_reserved +
65a15e06	317	xfs_perag_resv(pag, XFS_AG_RESV_RMAPBT)->ar_reserved <=
f21c57ed	318	pag->pagf_freeblks + pag->pagf_flcount);
74e502ac	319	#endif
cf8ce220 DW	320	out:
	321	return error;
	322	}
	323
	324	/* Allocate a block from the reservation. */
	325	void
	326	xfs_ag_resv_alloc_extent(
	327	struct xfs_perag *pag,
	328	enum xfs_ag_resv_type type,
	329	struct xfs_alloc_arg *args)
	330	{
	331	struct xfs_ag_resv *resv;
	332	xfs_extlen_t len;
	333	uint field;
	334
	335	trace_xfs_ag_resv_alloc_extent(pag, type, args->len);
	336
	337	switch (type) {
9760cac2 BF	338	case XFS_AG_RESV_AGFL:
9760cac2 BF	339	return;
cf8ce220	340	case XFS_AG_RESV_METADATA:
65a15e06	341	case XFS_AG_RESV_RMAPBT:
cf8ce220 DW	342	resv = xfs_perag_resv(pag, type);
	343	break;
	344	default:
	345	ASSERT(0);
	346	/* fall through */
	347	case XFS_AG_RESV_NONE:
	348	field = args->wasdel ? XFS_TRANS_SB_RES_FDBLOCKS :
	349	XFS_TRANS_SB_FDBLOCKS;
	350	xfs_trans_mod_sb(args->tp, field, -(int64_t)args->len);
	351	return;
	352	}
	353
	354	len = min_t(xfs_extlen_t, args->len, resv->ar_reserved);
	355	resv->ar_reserved -= len;
65a15e06	356	if (type == XFS_AG_RESV_RMAPBT)
cf8ce220 DW	357	return;
	358	/* Allocations of reserved blocks only need on-disk sb updates... */
	359	xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_RES_FDBLOCKS, -(int64_t)len);
	360	/* ...but non-reserved blocks need in-core and on-disk updates. */
	361	if (args->len > len)
	362	xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_FDBLOCKS,
	363	-((int64_t)args->len - len));
	364	}
	365
	366	/* Free a block to the reservation. */
	367	void
	368	xfs_ag_resv_free_extent(
	369	struct xfs_perag *pag,
	370	enum xfs_ag_resv_type type,
	371	struct xfs_trans *tp,
	372	xfs_extlen_t len)
	373	{
	374	xfs_extlen_t leftover;
	375	struct xfs_ag_resv *resv;
	376
	377	trace_xfs_ag_resv_free_extent(pag, type, len);
	378
	379	switch (type) {
9760cac2 BF	380	case XFS_AG_RESV_AGFL:
9760cac2 BF	381	return;
cf8ce220	382	case XFS_AG_RESV_METADATA:
65a15e06	383	case XFS_AG_RESV_RMAPBT:
cf8ce220 DW	384	resv = xfs_perag_resv(pag, type);
	385	break;
	386	default:
	387	ASSERT(0);
	388	/* fall through */
	389	case XFS_AG_RESV_NONE:
	390	xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (int64_t)len);
	391	return;
	392	}
	393
	394	leftover = min_t(xfs_extlen_t, len, resv->ar_asked - resv->ar_reserved);
	395	resv->ar_reserved += leftover;
65a15e06	396	if (type == XFS_AG_RESV_RMAPBT)
cf8ce220 DW	397	return;
	398	/* Freeing into the reserved pool only requires on-disk update... */
	399	xfs_trans_mod_sb(tp, XFS_TRANS_SB_RES_FDBLOCKS, len);
	400	/* ...but freeing beyond that requires in-core and on-disk update. */
	401	if (len > leftover)
	402	xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, len - leftover);
	403	}