[linux-2.6-block.git] / fs / xfs / 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 "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_sb.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_alloc.h"
#include "xfs_errortag.h"
#include "xfs_error.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
0b61f8a4	1	// SPDX-License-Identifier: GPL-2.0+
3fd129b6 DW	2	/*
3fd129b6 DW	3	* Copyright (C) 2016 Oracle. All Rights Reserved.
3fd129b6	4	* Author: Darrick J. Wong <darrick.wong@oracle.com>
3fd129b6 DW	5	*/
	6	#include "xfs.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"
e9e899a2	16	#include "xfs_errortag.h"
3fd129b6 DW	17	#include "xfs_error.h"
	18	#include "xfs_trace.h"
	19	#include "xfs_cksum.h"
	20	#include "xfs_trans.h"
	21	#include "xfs_bit.h"
	22	#include "xfs_bmap.h"
	23	#include "xfs_bmap_btree.h"
	24	#include "xfs_ag_resv.h"
	25	#include "xfs_trans_space.h"
	26	#include "xfs_rmap_btree.h"
	27	#include "xfs_btree.h"
84d69619	28	#include "xfs_refcount_btree.h"
76d771b4	29	#include "xfs_ialloc_btree.h"
3fd129b6 DW	30
	31	/*
	32	* Per-AG Block Reservations
	33	*
	34	* For some kinds of allocation group metadata structures, it is advantageous
	35	* to reserve a small number of blocks in each AG so that future expansions of
	36	* that data structure do not encounter ENOSPC because errors during a btree
	37	* split cause the filesystem to go offline.
	38	*
	39	* Prior to the introduction of reflink, this wasn't an issue because the free
	40	* space btrees maintain a reserve of space (the AGFL) to handle any expansion
	41	* that may be necessary; and allocations of other metadata (inodes, BMBT,
	42	* dir/attr) aren't restricted to a single AG. However, with reflink it is
	43	* possible to allocate all the space in an AG, have subsequent reflink/CoW
	44	* activity expand the refcount btree, and discover that there's no space left
	45	* to handle that expansion. Since we can calculate the maximum size of the
	46	* refcount btree, we can reserve space for it and avoid ENOSPC.
	47	*
	48	* Handling per-AG reservations consists of three changes to the allocator's
	49	* behavior: First, because these reservations are always needed, we decrease
	50	* the ag_max_usable counter to reflect the size of the AG after the reserved
	51	* blocks are taken. Second, the reservations must be reflected in the
	52	* fdblocks count to maintain proper accounting. Third, each AG must maintain
	53	* its own reserved block counter so that we can calculate the amount of space
	54	* that must remain free to maintain the reservations. Fourth, the "remaining
	55	* reserved blocks" count must be used when calculating the length of the
	56	* longest free extent in an AG and to clamp maxlen in the per-AG allocation
	57	* functions. In other words, we maintain a virtual allocation via in-core
	58	* accounting tricks so that we don't have to clean up after a crash. :)
	59	*
	60	* Reserved blocks can be managed by passing one of the enum xfs_ag_resv_type
	61	* values via struct xfs_alloc_arg or directly to the xfs_free_extent
	62	* function. It might seem a little funny to maintain a reservoir of blocks
	63	* to feed another reservoir, but the AGFL only holds enough blocks to get
	64	* through the next transaction. The per-AG reservation is to ensure (we
	65	* hope) that each AG never runs out of blocks. Each data structure wanting
	66	* to use the reservation system should update ask/used in xfs_ag_resv_init.
	67	*/
	68
	69	/*
	70	* Are we critically low on blocks? For now we'll define that as the number
	71	* of blocks we can get our hands on being less than 10% of what we reserved
	72	* or less than some arbitrary number (maximum btree height).
	73	*/
	74	bool
	75	xfs_ag_resv_critical(
	76	struct xfs_perag *pag,
	77	enum xfs_ag_resv_type type)
	78	{
	79	xfs_extlen_t avail;
	80	xfs_extlen_t orig;
	81
	82	switch (type) {
	83	case XFS_AG_RESV_METADATA:
21592863	84	avail = pag->pagf_freeblks - pag->pag_rmapbt_resv.ar_reserved;
3fd129b6 DW	85	orig = pag->pag_meta_resv.ar_asked;
3fd129b6 DW	86	break;
21592863	87	case XFS_AG_RESV_RMAPBT:
3fd129b6 DW	88	avail = pag->pagf_freeblks + pag->pagf_flcount -
3fd129b6 DW	89	pag->pag_meta_resv.ar_reserved;
21592863	90	orig = pag->pag_rmapbt_resv.ar_asked;
3fd129b6 DW	91	break;
	92	default:
	93	ASSERT(0);
	94	return false;
	95	}
	96
	97	trace_xfs_ag_resv_critical(pag, type, avail);
	98
	99	/* Critically low if less than 10% or max btree height remains. */
a35eb415	100	return XFS_TEST_ERROR(avail < orig / 10 \|\| avail < XFS_BTREE_MAXLEVELS,
9e24cfd0	101	pag->pag_mount, XFS_ERRTAG_AG_RESV_CRITICAL);
3fd129b6 DW	102	}
	103
	104	/*
	105	* How many blocks are reserved but not used, and therefore must not be
	106	* allocated away?
	107	*/
	108	xfs_extlen_t
	109	xfs_ag_resv_needed(
	110	struct xfs_perag *pag,
	111	enum xfs_ag_resv_type type)
	112	{
	113	xfs_extlen_t len;
	114
21592863	115	len = pag->pag_meta_resv.ar_reserved + pag->pag_rmapbt_resv.ar_reserved;
3fd129b6 DW	116	switch (type) {
3fd129b6 DW	117	case XFS_AG_RESV_METADATA:
21592863	118	case XFS_AG_RESV_RMAPBT:
3fd129b6 DW	119	len -= xfs_perag_resv(pag, type)->ar_reserved;
	120	break;
	121	case XFS_AG_RESV_NONE:
	122	/* empty */
	123	break;
	124	default:
	125	ASSERT(0);
	126	}
	127
	128	trace_xfs_ag_resv_needed(pag, type, len);
	129
	130	return len;
	131	}
	132
	133	/* Clean out a reservation */
	134	static int
	135	__xfs_ag_resv_free(
	136	struct xfs_perag *pag,
	137	enum xfs_ag_resv_type type)
	138	{
	139	struct xfs_ag_resv *resv;
	140	xfs_extlen_t oldresv;
	141	int error;
	142
	143	trace_xfs_ag_resv_free(pag, type, 0);
	144
	145	resv = xfs_perag_resv(pag, type);
9789dd9e DW	146	if (pag->pag_agno == 0)
9789dd9e DW	147	pag->pag_mount->m_ag_max_usable += resv->ar_asked;
3fd129b6	148	/*
21592863 BF	149	* RMAPBT blocks come from the AGFL and AGFL blocks are always
	150	* considered "free", so whatever was reserved at mount time must be
	151	* given back at umount.
3fd129b6	152	*/
21592863	153	if (type == XFS_AG_RESV_RMAPBT)
3fd129b6 DW	154	oldresv = resv->ar_orig_reserved;
	155	else
	156	oldresv = resv->ar_reserved;
	157	error = xfs_mod_fdblocks(pag->pag_mount, oldresv, true);
	158	resv->ar_reserved = 0;
	159	resv->ar_asked = 0;
d8cb5e42	160	resv->ar_orig_reserved = 0;
3fd129b6 DW	161
	162	if (error)
	163	trace_xfs_ag_resv_free_error(pag->pag_mount, pag->pag_agno,
	164	error, _RET_IP_);
	165	return error;
	166	}
	167
	168	/* Free a per-AG reservation. */
	169	int
	170	xfs_ag_resv_free(
	171	struct xfs_perag *pag)
	172	{
	173	int error;
	174	int err2;
	175
21592863	176	error = __xfs_ag_resv_free(pag, XFS_AG_RESV_RMAPBT);
3fd129b6 DW	177	err2 = __xfs_ag_resv_free(pag, XFS_AG_RESV_METADATA);
	178	if (err2 && !error)
	179	error = err2;
	180	return error;
	181	}
	182
	183	static int
	184	__xfs_ag_resv_init(
	185	struct xfs_perag *pag,
	186	enum xfs_ag_resv_type type,
	187	xfs_extlen_t ask,
	188	xfs_extlen_t used)
	189	{
	190	struct xfs_mount *mp = pag->pag_mount;
	191	struct xfs_ag_resv *resv;
	192	int error;
d8cb5e42	193	xfs_extlen_t hidden_space;
3fd129b6	194
3fd129b6 DW	195	if (used > ask)
3fd129b6 DW	196	ask = used;
3fd129b6	197
d8cb5e42 DW	198	switch (type) {
	199	case XFS_AG_RESV_RMAPBT:
	200	/*
	201	* Space taken by the rmapbt is not subtracted from fdblocks
	202	* because the rmapbt lives in the free space. Here we must
	203	* subtract the entire reservation from fdblocks so that we
	204	* always have blocks available for rmapbt expansion.
	205	*/
	206	hidden_space = ask;
	207	break;
	208	case XFS_AG_RESV_METADATA:
	209	/*
	210	* Space taken by all other metadata btrees are accounted
	211	* on-disk as used space. We therefore only hide the space
	212	* that is reserved but not used by the trees.
	213	*/
	214	hidden_space = ask - used;
	215	break;
	216	default:
	217	ASSERT(0);
	218	return -EINVAL;
	219	}
	220	error = xfs_mod_fdblocks(mp, -(int64_t)hidden_space, true);
4dfa2b84	221	if (error) {
3fd129b6 DW	222	trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno,
3fd129b6 DW	223	error, _RET_IP_);
76d771b4 CH	224	xfs_warn(mp,
	225	"Per-AG reservation for AG %u failed. Filesystem may run out of space.",
	226	pag->pag_agno);
4dfa2b84 CH	227	return error;
4dfa2b84 CH	228	}
3fd129b6	229
9789dd9e DW	230	/*
	231	* Reduce the maximum per-AG allocation length by however much we're
	232	* trying to reserve for an AG. Since this is a filesystem-wide
	233	* counter, we only make the adjustment for AG 0. This assumes that
	234	* there aren't any AGs hungrier for per-AG reservation than AG 0.
	235	*/
	236	if (pag->pag_agno == 0)
	237	mp->m_ag_max_usable -= ask;
4dfa2b84 CH	238
	239	resv = xfs_perag_resv(pag, type);
	240	resv->ar_asked = ask;
d8cb5e42 DW	241	resv->ar_orig_reserved = hidden_space;
d8cb5e42 DW	242	resv->ar_reserved = ask - used;
4dfa2b84 CH	243
	244	trace_xfs_ag_resv_init(pag, type, ask);
	245	return 0;
3fd129b6 DW	246	}
	247
	248	/* Create a per-AG block reservation. */
	249	int
	250	xfs_ag_resv_init(
ebcbef3a DW	251	struct xfs_perag *pag,
ebcbef3a DW	252	struct xfs_trans *tp)
3fd129b6	253	{
76d771b4 CH	254	struct xfs_mount *mp = pag->pag_mount;
76d771b4 CH	255	xfs_agnumber_t agno = pag->pag_agno;
3fd129b6 DW	256	xfs_extlen_t ask;
	257	xfs_extlen_t used;
	258	int error = 0;
	259
	260	/* Create the metadata reservation. */
	261	if (pag->pag_meta_resv.ar_asked == 0) {
	262	ask = used = 0;
	263
ebcbef3a	264	error = xfs_refcountbt_calc_reserves(mp, tp, agno, &ask, &used);
84d69619 DW	265	if (error)
	266	goto out;
	267
ebcbef3a	268	error = xfs_finobt_calc_reserves(mp, tp, agno, &ask, &used);
3fd129b6 DW	269	if (error)
3fd129b6 DW	270	goto out;
76d771b4 CH	271
	272	error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
	273	ask, used);
	274	if (error) {
	275	/*
	276	* Because we didn't have per-AG reservations when the
	277	* finobt feature was added we might not be able to
	278	* reserve all needed blocks. Warn and fall back to the
	279	* old and potentially buggy code in that case, but
	280	* ensure we do have the reservation for the refcountbt.
	281	*/
	282	ask = used = 0;
	283
	284	mp->m_inotbt_nores = true;
	285
ebcbef3a	286	error = xfs_refcountbt_calc_reserves(mp, tp, agno, &ask,
76d771b4 CH	287	&used);
	288	if (error)
	289	goto out;
	290
	291	error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
	292	ask, used);
	293	if (error)
	294	goto out;
	295	}
3fd129b6 DW	296	}
3fd129b6 DW	297
21592863 BF	298	/* Create the RMAPBT metadata reservation */
21592863 BF	299	if (pag->pag_rmapbt_resv.ar_asked == 0) {
3fd129b6 DW	300	ask = used = 0;
3fd129b6 DW	301
ebcbef3a	302	error = xfs_rmapbt_calc_reserves(mp, tp, agno, &ask, &used);
84d69619 DW	303	if (error)
	304	goto out;
	305
21592863	306	error = __xfs_ag_resv_init(pag, XFS_AG_RESV_RMAPBT, ask, used);
3fd129b6 DW	307	if (error)
	308	goto out;
	309	}
	310
76d771b4 CH	311	#ifdef DEBUG
76d771b4 CH	312	/* need to read in the AGF for the ASSERT below to work */
ebcbef3a	313	error = xfs_alloc_pagf_init(pag->pag_mount, tp, pag->pag_agno, 0);
76d771b4 CH	314	if (error)
	315	return error;
	316
20e73b00	317	ASSERT(xfs_perag_resv(pag, XFS_AG_RESV_METADATA)->ar_reserved +
21592863	318	xfs_perag_resv(pag, XFS_AG_RESV_RMAPBT)->ar_reserved <=
20e73b00	319	pag->pagf_freeblks + pag->pagf_flcount);
76d771b4	320	#endif
3fd129b6 DW	321	out:
	322	return error;
	323	}
	324
	325	/* Allocate a block from the reservation. */
	326	void
	327	xfs_ag_resv_alloc_extent(
	328	struct xfs_perag *pag,
	329	enum xfs_ag_resv_type type,
	330	struct xfs_alloc_arg *args)
	331	{
	332	struct xfs_ag_resv *resv;
	333	xfs_extlen_t len;
	334	uint field;
	335
	336	trace_xfs_ag_resv_alloc_extent(pag, type, args->len);
	337
	338	switch (type) {
0ab32086 BF	339	case XFS_AG_RESV_AGFL:
0ab32086 BF	340	return;
3fd129b6	341	case XFS_AG_RESV_METADATA:
21592863	342	case XFS_AG_RESV_RMAPBT:
3fd129b6 DW	343	resv = xfs_perag_resv(pag, type);
	344	break;
	345	default:
	346	ASSERT(0);
	347	/* fall through */
	348	case XFS_AG_RESV_NONE:
	349	field = args->wasdel ? XFS_TRANS_SB_RES_FDBLOCKS :
	350	XFS_TRANS_SB_FDBLOCKS;
	351	xfs_trans_mod_sb(args->tp, field, -(int64_t)args->len);
	352	return;
	353	}
	354
	355	len = min_t(xfs_extlen_t, args->len, resv->ar_reserved);
	356	resv->ar_reserved -= len;
21592863	357	if (type == XFS_AG_RESV_RMAPBT)
3fd129b6 DW	358	return;
	359	/* Allocations of reserved blocks only need on-disk sb updates... */
	360	xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_RES_FDBLOCKS, -(int64_t)len);
	361	/* ...but non-reserved blocks need in-core and on-disk updates. */
	362	if (args->len > len)
	363	xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_FDBLOCKS,
	364	-((int64_t)args->len - len));
	365	}
	366
	367	/* Free a block to the reservation. */
	368	void
	369	xfs_ag_resv_free_extent(
	370	struct xfs_perag *pag,
	371	enum xfs_ag_resv_type type,
	372	struct xfs_trans *tp,
	373	xfs_extlen_t len)
	374	{
	375	xfs_extlen_t leftover;
	376	struct xfs_ag_resv *resv;
	377
	378	trace_xfs_ag_resv_free_extent(pag, type, len);
	379
	380	switch (type) {
0ab32086 BF	381	case XFS_AG_RESV_AGFL:
0ab32086 BF	382	return;
3fd129b6	383	case XFS_AG_RESV_METADATA:
21592863	384	case XFS_AG_RESV_RMAPBT:
3fd129b6 DW	385	resv = xfs_perag_resv(pag, type);
	386	break;
	387	default:
	388	ASSERT(0);
	389	/* fall through */
	390	case XFS_AG_RESV_NONE:
	391	xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (int64_t)len);
	392	return;
	393	}
	394
	395	leftover = min_t(xfs_extlen_t, len, resv->ar_asked - resv->ar_reserved);
	396	resv->ar_reserved += leftover;
21592863	397	if (type == XFS_AG_RESV_RMAPBT)
3fd129b6 DW	398	return;
	399	/* Freeing into the reserved pool only requires on-disk update... */
	400	xfs_trans_mod_sb(tp, XFS_TRANS_SB_RES_FDBLOCKS, len);
	401	/* ...but freeing beyond that requires in-core and on-disk update. */
	402	if (len > leftover)
	403	xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, len - leftover);
	404	}