[linux-2.6-block.git] / fs / xfs / libxfs / xfs_ag_resv.c

/*
 * Copyright (C) 2016 Oracle.  All Rights Reserved.
 *
 * Author: Darrick J. Wong <darrick.wong@oracle.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
 */
#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;

	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			reserved;

	if (used > ask)
		ask = used;
	reserved = ask - used;

	error = xfs_mod_fdblocks(mp, -(int64_t)reserved, 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_reserved = resv->ar_orig_reserved = reserved;

	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_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, agno, &ask, &used);
		if (error)
			goto out;

		error = xfs_finobt_calc_reserves(mp, 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, 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, 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, NULL, 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
3fd129b6 DW	1	/*
	2	* Copyright (C) 2016 Oracle. All Rights Reserved.
	3	*
	4	* Author: Darrick J. Wong <darrick.wong@oracle.com>
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version 2
	9	* of the License, or (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it would be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write the Free Software Foundation,
	18	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
	19	*/
	20	#include "xfs.h"
	21	#include "xfs_fs.h"
	22	#include "xfs_shared.h"
	23	#include "xfs_format.h"
	24	#include "xfs_log_format.h"
	25	#include "xfs_trans_resv.h"
	26	#include "xfs_sb.h"
	27	#include "xfs_mount.h"
	28	#include "xfs_defer.h"
	29	#include "xfs_alloc.h"
e9e899a2	30	#include "xfs_errortag.h"
3fd129b6 DW	31	#include "xfs_error.h"
	32	#include "xfs_trace.h"
	33	#include "xfs_cksum.h"
	34	#include "xfs_trans.h"
	35	#include "xfs_bit.h"
	36	#include "xfs_bmap.h"
	37	#include "xfs_bmap_btree.h"
	38	#include "xfs_ag_resv.h"
	39	#include "xfs_trans_space.h"
	40	#include "xfs_rmap_btree.h"
	41	#include "xfs_btree.h"
84d69619	42	#include "xfs_refcount_btree.h"
76d771b4	43	#include "xfs_ialloc_btree.h"
3fd129b6 DW	44
	45	/*
	46	* Per-AG Block Reservations
	47	*
	48	* For some kinds of allocation group metadata structures, it is advantageous
	49	* to reserve a small number of blocks in each AG so that future expansions of
	50	* that data structure do not encounter ENOSPC because errors during a btree
	51	* split cause the filesystem to go offline.
	52	*
	53	* Prior to the introduction of reflink, this wasn't an issue because the free
	54	* space btrees maintain a reserve of space (the AGFL) to handle any expansion
	55	* that may be necessary; and allocations of other metadata (inodes, BMBT,
	56	* dir/attr) aren't restricted to a single AG. However, with reflink it is
	57	* possible to allocate all the space in an AG, have subsequent reflink/CoW
	58	* activity expand the refcount btree, and discover that there's no space left
	59	* to handle that expansion. Since we can calculate the maximum size of the
	60	* refcount btree, we can reserve space for it and avoid ENOSPC.
	61	*
	62	* Handling per-AG reservations consists of three changes to the allocator's
	63	* behavior: First, because these reservations are always needed, we decrease
	64	* the ag_max_usable counter to reflect the size of the AG after the reserved
	65	* blocks are taken. Second, the reservations must be reflected in the
	66	* fdblocks count to maintain proper accounting. Third, each AG must maintain
	67	* its own reserved block counter so that we can calculate the amount of space
	68	* that must remain free to maintain the reservations. Fourth, the "remaining
	69	* reserved blocks" count must be used when calculating the length of the
	70	* longest free extent in an AG and to clamp maxlen in the per-AG allocation
	71	* functions. In other words, we maintain a virtual allocation via in-core
	72	* accounting tricks so that we don't have to clean up after a crash. :)
	73	*
	74	* Reserved blocks can be managed by passing one of the enum xfs_ag_resv_type
	75	* values via struct xfs_alloc_arg or directly to the xfs_free_extent
	76	* function. It might seem a little funny to maintain a reservoir of blocks
	77	* to feed another reservoir, but the AGFL only holds enough blocks to get
	78	* through the next transaction. The per-AG reservation is to ensure (we
	79	* hope) that each AG never runs out of blocks. Each data structure wanting
	80	* to use the reservation system should update ask/used in xfs_ag_resv_init.
	81	*/
	82
	83	/*
	84	* Are we critically low on blocks? For now we'll define that as the number
	85	* of blocks we can get our hands on being less than 10% of what we reserved
	86	* or less than some arbitrary number (maximum btree height).
	87	*/
	88	bool
	89	xfs_ag_resv_critical(
	90	struct xfs_perag *pag,
	91	enum xfs_ag_resv_type type)
	92	{
	93	xfs_extlen_t avail;
	94	xfs_extlen_t orig;
	95
	96	switch (type) {
	97	case XFS_AG_RESV_METADATA:
21592863	98	avail = pag->pagf_freeblks - pag->pag_rmapbt_resv.ar_reserved;
3fd129b6 DW	99	orig = pag->pag_meta_resv.ar_asked;
3fd129b6 DW	100	break;
21592863	101	case XFS_AG_RESV_RMAPBT:
3fd129b6 DW	102	avail = pag->pagf_freeblks + pag->pagf_flcount -
3fd129b6 DW	103	pag->pag_meta_resv.ar_reserved;
21592863	104	orig = pag->pag_rmapbt_resv.ar_asked;
3fd129b6 DW	105	break;
	106	default:
	107	ASSERT(0);
	108	return false;
	109	}
	110
	111	trace_xfs_ag_resv_critical(pag, type, avail);
	112
	113	/* Critically low if less than 10% or max btree height remains. */
a35eb415	114	return XFS_TEST_ERROR(avail < orig / 10 \|\| avail < XFS_BTREE_MAXLEVELS,
9e24cfd0	115	pag->pag_mount, XFS_ERRTAG_AG_RESV_CRITICAL);
3fd129b6 DW	116	}
	117
	118	/*
	119	* How many blocks are reserved but not used, and therefore must not be
	120	* allocated away?
	121	*/
	122	xfs_extlen_t
	123	xfs_ag_resv_needed(
	124	struct xfs_perag *pag,
	125	enum xfs_ag_resv_type type)
	126	{
	127	xfs_extlen_t len;
	128
21592863	129	len = pag->pag_meta_resv.ar_reserved + pag->pag_rmapbt_resv.ar_reserved;
3fd129b6 DW	130	switch (type) {
3fd129b6 DW	131	case XFS_AG_RESV_METADATA:
21592863	132	case XFS_AG_RESV_RMAPBT:
3fd129b6 DW	133	len -= xfs_perag_resv(pag, type)->ar_reserved;
	134	break;
	135	case XFS_AG_RESV_NONE:
	136	/* empty */
	137	break;
	138	default:
	139	ASSERT(0);
	140	}
	141
	142	trace_xfs_ag_resv_needed(pag, type, len);
	143
	144	return len;
	145	}
	146
	147	/* Clean out a reservation */
	148	static int
	149	__xfs_ag_resv_free(
	150	struct xfs_perag *pag,
	151	enum xfs_ag_resv_type type)
	152	{
	153	struct xfs_ag_resv *resv;
	154	xfs_extlen_t oldresv;
	155	int error;
	156
	157	trace_xfs_ag_resv_free(pag, type, 0);
	158
	159	resv = xfs_perag_resv(pag, type);
9789dd9e DW	160	if (pag->pag_agno == 0)
9789dd9e DW	161	pag->pag_mount->m_ag_max_usable += resv->ar_asked;
3fd129b6	162	/*
21592863 BF	163	* RMAPBT blocks come from the AGFL and AGFL blocks are always
	164	* considered "free", so whatever was reserved at mount time must be
	165	* given back at umount.
3fd129b6	166	*/
21592863	167	if (type == XFS_AG_RESV_RMAPBT)
3fd129b6 DW	168	oldresv = resv->ar_orig_reserved;
	169	else
	170	oldresv = resv->ar_reserved;
	171	error = xfs_mod_fdblocks(pag->pag_mount, oldresv, true);
	172	resv->ar_reserved = 0;
	173	resv->ar_asked = 0;
	174
	175	if (error)
	176	trace_xfs_ag_resv_free_error(pag->pag_mount, pag->pag_agno,
	177	error, _RET_IP_);
	178	return error;
	179	}
	180
	181	/* Free a per-AG reservation. */
	182	int
	183	xfs_ag_resv_free(
	184	struct xfs_perag *pag)
	185	{
	186	int error;
	187	int err2;
	188
21592863	189	error = __xfs_ag_resv_free(pag, XFS_AG_RESV_RMAPBT);
3fd129b6 DW	190	err2 = __xfs_ag_resv_free(pag, XFS_AG_RESV_METADATA);
	191	if (err2 && !error)
	192	error = err2;
	193	return error;
	194	}
	195
	196	static int
	197	__xfs_ag_resv_init(
	198	struct xfs_perag *pag,
	199	enum xfs_ag_resv_type type,
	200	xfs_extlen_t ask,
	201	xfs_extlen_t used)
	202	{
	203	struct xfs_mount *mp = pag->pag_mount;
	204	struct xfs_ag_resv *resv;
	205	int error;
4dfa2b84	206	xfs_extlen_t reserved;
3fd129b6	207
3fd129b6 DW	208	if (used > ask)
3fd129b6 DW	209	ask = used;
4dfa2b84	210	reserved = ask - used;
3fd129b6	211
4dfa2b84 CH	212	error = xfs_mod_fdblocks(mp, -(int64_t)reserved, true);
4dfa2b84 CH	213	if (error) {
3fd129b6 DW	214	trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno,
3fd129b6 DW	215	error, _RET_IP_);
76d771b4 CH	216	xfs_warn(mp,
	217	"Per-AG reservation for AG %u failed. Filesystem may run out of space.",
	218	pag->pag_agno);
4dfa2b84 CH	219	return error;
4dfa2b84 CH	220	}
3fd129b6	221
9789dd9e DW	222	/*
	223	* Reduce the maximum per-AG allocation length by however much we're
	224	* trying to reserve for an AG. Since this is a filesystem-wide
	225	* counter, we only make the adjustment for AG 0. This assumes that
	226	* there aren't any AGs hungrier for per-AG reservation than AG 0.
	227	*/
	228	if (pag->pag_agno == 0)
	229	mp->m_ag_max_usable -= ask;
4dfa2b84 CH	230
	231	resv = xfs_perag_resv(pag, type);
	232	resv->ar_asked = ask;
	233	resv->ar_reserved = resv->ar_orig_reserved = reserved;
	234
	235	trace_xfs_ag_resv_init(pag, type, ask);
	236	return 0;
3fd129b6 DW	237	}
	238
	239	/* Create a per-AG block reservation. */
	240	int
	241	xfs_ag_resv_init(
	242	struct xfs_perag *pag)
	243	{
76d771b4 CH	244	struct xfs_mount *mp = pag->pag_mount;
76d771b4 CH	245	xfs_agnumber_t agno = pag->pag_agno;
3fd129b6 DW	246	xfs_extlen_t ask;
	247	xfs_extlen_t used;
	248	int error = 0;
	249
	250	/* Create the metadata reservation. */
	251	if (pag->pag_meta_resv.ar_asked == 0) {
	252	ask = used = 0;
	253
76d771b4	254	error = xfs_refcountbt_calc_reserves(mp, agno, &ask, &used);
84d69619 DW	255	if (error)
	256	goto out;
	257
76d771b4	258	error = xfs_finobt_calc_reserves(mp, agno, &ask, &used);
3fd129b6 DW	259	if (error)
3fd129b6 DW	260	goto out;
76d771b4 CH	261
	262	error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
	263	ask, used);
	264	if (error) {
	265	/*
	266	* Because we didn't have per-AG reservations when the
	267	* finobt feature was added we might not be able to
	268	* reserve all needed blocks. Warn and fall back to the
	269	* old and potentially buggy code in that case, but
	270	* ensure we do have the reservation for the refcountbt.
	271	*/
	272	ask = used = 0;
	273
	274	mp->m_inotbt_nores = true;
	275
	276	error = xfs_refcountbt_calc_reserves(mp, agno, &ask,
	277	&used);
	278	if (error)
	279	goto out;
	280
	281	error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
	282	ask, used);
	283	if (error)
	284	goto out;
	285	}
3fd129b6 DW	286	}
3fd129b6 DW	287
21592863 BF	288	/* Create the RMAPBT metadata reservation */
21592863 BF	289	if (pag->pag_rmapbt_resv.ar_asked == 0) {
3fd129b6 DW	290	ask = used = 0;
3fd129b6 DW	291
76d771b4	292	error = xfs_rmapbt_calc_reserves(mp, agno, &ask, &used);
84d69619 DW	293	if (error)
	294	goto out;
	295
21592863	296	error = __xfs_ag_resv_init(pag, XFS_AG_RESV_RMAPBT, ask, used);
3fd129b6 DW	297	if (error)
	298	goto out;
	299	}
	300
76d771b4 CH	301	#ifdef DEBUG
	302	/* need to read in the AGF for the ASSERT below to work */
	303	error = xfs_alloc_pagf_init(pag->pag_mount, NULL, pag->pag_agno, 0);
	304	if (error)
	305	return error;
	306
20e73b00	307	ASSERT(xfs_perag_resv(pag, XFS_AG_RESV_METADATA)->ar_reserved +
21592863	308	xfs_perag_resv(pag, XFS_AG_RESV_RMAPBT)->ar_reserved <=
20e73b00	309	pag->pagf_freeblks + pag->pagf_flcount);
76d771b4	310	#endif
3fd129b6 DW	311	out:
	312	return error;
	313	}
	314
	315	/* Allocate a block from the reservation. */
	316	void
	317	xfs_ag_resv_alloc_extent(
	318	struct xfs_perag *pag,
	319	enum xfs_ag_resv_type type,
	320	struct xfs_alloc_arg *args)
	321	{
	322	struct xfs_ag_resv *resv;
	323	xfs_extlen_t len;
	324	uint field;
	325
	326	trace_xfs_ag_resv_alloc_extent(pag, type, args->len);
	327
	328	switch (type) {
0ab32086 BF	329	case XFS_AG_RESV_AGFL:
0ab32086 BF	330	return;
3fd129b6	331	case XFS_AG_RESV_METADATA:
21592863	332	case XFS_AG_RESV_RMAPBT:
3fd129b6 DW	333	resv = xfs_perag_resv(pag, type);
	334	break;
	335	default:
	336	ASSERT(0);
	337	/* fall through */
	338	case XFS_AG_RESV_NONE:
	339	field = args->wasdel ? XFS_TRANS_SB_RES_FDBLOCKS :
	340	XFS_TRANS_SB_FDBLOCKS;
	341	xfs_trans_mod_sb(args->tp, field, -(int64_t)args->len);
	342	return;
	343	}
	344
	345	len = min_t(xfs_extlen_t, args->len, resv->ar_reserved);
	346	resv->ar_reserved -= len;
21592863	347	if (type == XFS_AG_RESV_RMAPBT)
3fd129b6 DW	348	return;
	349	/* Allocations of reserved blocks only need on-disk sb updates... */
	350	xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_RES_FDBLOCKS, -(int64_t)len);
	351	/* ...but non-reserved blocks need in-core and on-disk updates. */
	352	if (args->len > len)
	353	xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_FDBLOCKS,
	354	-((int64_t)args->len - len));
	355	}
	356
	357	/* Free a block to the reservation. */
	358	void
	359	xfs_ag_resv_free_extent(
	360	struct xfs_perag *pag,
	361	enum xfs_ag_resv_type type,
	362	struct xfs_trans *tp,
	363	xfs_extlen_t len)
	364	{
	365	xfs_extlen_t leftover;
	366	struct xfs_ag_resv *resv;
	367
	368	trace_xfs_ag_resv_free_extent(pag, type, len);
	369
	370	switch (type) {
0ab32086 BF	371	case XFS_AG_RESV_AGFL:
0ab32086 BF	372	return;
3fd129b6	373	case XFS_AG_RESV_METADATA:
21592863	374	case XFS_AG_RESV_RMAPBT:
3fd129b6 DW	375	resv = xfs_perag_resv(pag, type);
	376	break;
	377	default:
	378	ASSERT(0);
	379	/* fall through */
	380	case XFS_AG_RESV_NONE:
	381	xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (int64_t)len);
	382	return;
	383	}
	384
	385	leftover = min_t(xfs_extlen_t, len, resv->ar_asked - resv->ar_reserved);
	386	resv->ar_reserved += leftover;
21592863	387	if (type == XFS_AG_RESV_RMAPBT)
3fd129b6 DW	388	return;
	389	/* Freeing into the reserved pool only requires on-disk update... */
	390	xfs_trans_mod_sb(tp, XFS_TRANS_SB_RES_FDBLOCKS, len);
	391	/* ...but freeing beyond that requires in-core and on-disk update. */
	392	if (len > leftover)
	393	xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, len - leftover);
	394	}