Merge branch 'xfs-4.9-reflink-prep' into for-next

				   xfs_inode_fork.o \

				   xfs_inode_buf.o \

				   xfs_log_rlimit.o \

				   xfs_ag_resv.o \

				   xfs_rmap.o \

				   xfs_rmap_btree.o \

				   xfs_sb.o \

/*

 * 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_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"

/*

 * 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_agfl_resv.ar_reserved;

		orig = pag->pag_meta_resv.ar_asked;

		break;

	case XFS_AG_RESV_AGFL:

		avail = pag->pagf_freeblks + pag->pagf_flcount -

			pag->pag_meta_resv.ar_reserved;

		orig = pag->pag_agfl_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 avail < orig / 10 || avail < XFS_BTREE_MAXLEVELS;

}

/*

 * 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_agfl_resv.ar_reserved;

	switch (type) {

	case XFS_AG_RESV_METADATA:

	case XFS_AG_RESV_AGFL:

		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);

	pag->pag_mount->m_ag_max_usable += resv->ar_asked;

	/*

	 * AGFL blocks are always considered "free", so whatever

	 * was reserved at mount time must be given back at umount.

	 */

	if (type == XFS_AG_RESV_AGFL)

		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_AGFL);

	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;

	resv = xfs_perag_resv(pag, type);

	if (used > ask)

		ask = used;

	resv->ar_asked = ask;

	resv->ar_reserved = resv->ar_orig_reserved = ask - used;

	mp->m_ag_max_usable -= ask;

	trace_xfs_ag_resv_init(pag, type, ask);

	error = xfs_mod_fdblocks(mp, -(int64_t)resv->ar_reserved, true);

	if (error)

		trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno,

				error, _RET_IP_);

	return error;

}

/* Create a per-AG block reservation. */

int

xfs_ag_resv_init(

	struct xfs_perag		*pag)

{

	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_ag_resv_init(pag, XFS_AG_RESV_METADATA,

				ask, used);

		if (error)

			goto out;

	}

	/* Create the AGFL metadata reservation */

	if (pag->pag_agfl_resv.ar_asked == 0) {

		ask = used = 0;

		error = __xfs_ag_resv_init(pag, XFS_AG_RESV_AGFL, ask, used);

		if (error)

			goto out;

	}

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_METADATA:

	case XFS_AG_RESV_AGFL:

		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_AGFL)

		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_METADATA:

	case XFS_AG_RESV_AGFL:

		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_AGFL)

		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);

}

/*

 * 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.

 */

#ifndef __XFS_AG_RESV_H__

#define	__XFS_AG_RESV_H__

int xfs_ag_resv_free(struct xfs_perag *pag);

int xfs_ag_resv_init(struct xfs_perag *pag);

bool xfs_ag_resv_critical(struct xfs_perag *pag, enum xfs_ag_resv_type type);

xfs_extlen_t xfs_ag_resv_needed(struct xfs_perag *pag,

		enum xfs_ag_resv_type type);

void xfs_ag_resv_alloc_extent(struct xfs_perag *pag, enum xfs_ag_resv_type type,

		struct xfs_alloc_arg *args);

void xfs_ag_resv_free_extent(struct xfs_perag *pag, enum xfs_ag_resv_type type,

		struct xfs_trans *tp, xfs_extlen_t len);

#endif	/* __XFS_AG_RESV_H__ */

#include "xfs_trans.h"

#include "xfs_buf_item.h"

#include "xfs_log.h"

#include "xfs_ag_resv.h"

struct workqueue_struct *xfs_alloc_wq;

 * extents need to be actually allocated. To get around this, we explicitly set

 * aside a few blocks which will not be reserved in delayed allocation.

 *

 * When rmap is disabled, we need to reserve 4 fsbs _per AG_ for the freelist

 * and 4 more to handle a potential split of the file's bmap btree.

 *

 * When rmap is enabled, we must also be able to handle two rmap btree inserts

 * to record both the file data extent and a new bmbt block.  The bmbt block

 * might not be in the same AG as the file data extent.  In the worst case

 * the bmap btree splits multiple levels and all the new blocks come from

 * different AGs, so set aside enough to handle rmap btree splits in all AGs.

 * We need to reserve 4 fsbs _per AG_ for the freelist and 4 more to handle a

 * potential split of the file's bmap btree.

 */

unsigned int

xfs_alloc_set_aside(

	unsigned int		blocks;

	blocks = 4 + (mp->m_sb.sb_agcount * XFS_ALLOC_AGFL_RESERVE);

	if (xfs_sb_version_hasrmapbt(&mp->m_sb))

		blocks += mp->m_sb.sb_agcount * mp->m_rmap_maxlevels;

	return blocks;

}

	xfs_alloc_arg_t	*args)	/* argument structure for allocation */

{

	int		error=0;

	xfs_extlen_t	reservation;

	xfs_extlen_t	oldmax;

	ASSERT(args->minlen > 0);

	ASSERT(args->maxlen > 0);

	ASSERT(args->minlen <= args->maxlen);

	ASSERT(args->mod < args->prod);

	ASSERT(args->alignment > 0);

	/*

	 * Clamp maxlen to the amount of free space minus any reservations

	 * that have been made.

	 */

	oldmax = args->maxlen;

	reservation = xfs_ag_resv_needed(args->pag, args->resv);

	if (args->maxlen > args->pag->pagf_freeblks - reservation)

		args->maxlen = args->pag->pagf_freeblks - reservation;

	if (args->maxlen == 0) {

		args->agbno = NULLAGBLOCK;

		args->maxlen = oldmax;

		return 0;

	}

	/*

	 * Branch to correct routine based on the type.

	 */

		/* NOTREACHED */

	}

	args->maxlen = oldmax;

	if (error || args->agbno == NULLAGBLOCK)

		return error;

	ASSERT(args->len >= args->minlen);

	ASSERT(args->len <= args->maxlen);

	ASSERT(!args->wasfromfl || !args->isfl);

	ASSERT(!args->wasfromfl || args->resv != XFS_AG_RESV_AGFL);

	ASSERT(args->agbno % args->alignment == 0);

	/* if not file data, insert new block into the reverse map btree */

					      args->agbno, args->len));

	}

	if (!args->isfl) {

		xfs_trans_mod_sb(args->tp, args->wasdel ?

				 XFS_TRANS_SB_RES_FDBLOCKS :

				 XFS_TRANS_SB_FDBLOCKS,

				 -((long)(args->len)));

	}

	xfs_ag_resv_alloc_extent(args->pag, args->resv, args);

	XFS_STATS_INC(args->mp, xs_allocx);

	XFS_STATS_ADD(args->mp, xs_allocb, args->len);

	int		*stat)	/* status: 0-freelist, 1-normal/none */

{

	struct xfs_owner_info	oinfo;

	struct xfs_perag	*pag;

	int		error;

	xfs_agblock_t	fbno;

	xfs_extlen_t	flen;

	 * to respect minleft even when pulling from the

	 * freelist.

	 */

	else if (args->minlen == 1 && args->alignment == 1 && !args->isfl &&

	else if (args->minlen == 1 && args->alignment == 1 &&

		 args->resv != XFS_AG_RESV_AGFL &&

		 (be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_flcount)

		  > args->minleft)) {

		error = xfs_alloc_get_freelist(args->tp, args->agbp, &fbno, 0);

			/*

			 * If we're feeding an AGFL block to something that

			 * doesn't live in the free space, we need to clear

			 * out the OWN_AG rmap.

			 * out the OWN_AG rmap and add the block back to

			 * the AGFL per-AG reservation.

			 */

			xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_AG);

			error = xfs_rmap_free(args->tp, args->agbp, args->agno,

					fbno, 1, &oinfo);

			if (error)

				goto error0;

			pag = xfs_perag_get(args->mp, args->agno);

			xfs_ag_resv_free_extent(pag, XFS_AG_RESV_AGFL,

					args->tp, 1);

			xfs_perag_put(pag);

			*stat = 0;

			return 0;

	xfs_agblock_t		bno,

	xfs_extlen_t		len,

	struct xfs_owner_info	*oinfo,

	int			isfl)

	enum xfs_ag_resv_type	type)

{

	xfs_btree_cur_t	*bno_cur;	/* cursor for by-block btree */

	xfs_btree_cur_t	*cnt_cur;	/* cursor for by-size btree */

	 */

	pag = xfs_perag_get(mp, agno);

	error = xfs_alloc_update_counters(tp, pag, agbp, len);

	xfs_ag_resv_free_extent(pag, type, tp, len);

	xfs_perag_put(pag);

	if (error)

		goto error0;

	if (!isfl)

		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (long)len);

	XFS_STATS_INC(mp, xs_freex);

	XFS_STATS_ADD(mp, xs_freeb, len);

	trace_xfs_free_extent(mp, agno, bno, len, isfl, haveleft, haveright);

	trace_xfs_free_extent(mp, agno, bno, len, type == XFS_AG_RESV_AGFL,

			haveleft, haveright);

	return 0;

 error0:

	trace_xfs_free_extent(mp, agno, bno, len, isfl, -1, -1);

	trace_xfs_free_extent(mp, agno, bno, len, type == XFS_AG_RESV_AGFL,

			-1, -1);

	if (bno_cur)

		xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);

	if (cnt_cur)

}

/*

 * Find the length of the longest extent in an AG.

 * Find the length of the longest extent in an AG.  The 'need' parameter

 * specifies how much space we're going to need for the AGFL and the

 * 'reserved' parameter tells us how many blocks in this AG are reserved for

 * other callers.

 */

xfs_extlen_t

xfs_alloc_longest_free_extent(

	struct xfs_mount	*mp,

	struct xfs_perag	*pag,

	xfs_extlen_t		need)

	xfs_extlen_t		need,

	xfs_extlen_t		reserved)

{

	xfs_extlen_t		delta = 0;

	/*

	 * If the AGFL needs a recharge, we'll have to subtract that from the

	 * longest extent.

	 */

	if (need > pag->pagf_flcount)

		delta = need - pag->pagf_flcount;

	/*

	 * If we cannot maintain others' reservations with space from the

	 * not-longest freesp extents, we'll have to subtract /that/ from

	 * the longest extent too.

	 */

	if (pag->pagf_freeblks - pag->pagf_longest < reserved)

		delta += reserved - (pag->pagf_freeblks - pag->pagf_longest);

	/*

	 * If the longest extent is long enough to satisfy all the

	 * reservations and AGFL rules in place, we can return this extent.

	 */

	if (pag->pagf_longest > delta)

		return pag->pagf_longest - delta;

	/* Otherwise, let the caller try for 1 block if there's space. */

	return pag->pagf_flcount > 0 || pag->pagf_longest > 0;

}

{

	struct xfs_perag	*pag = args->pag;

	xfs_extlen_t		longest;

	xfs_extlen_t		reservation; /* blocks that are still reserved */

	int			available;

	if (flags & XFS_ALLOC_FLAG_FREEING)

		return true;

	reservation = xfs_ag_resv_needed(pag, args->resv);

	/* do we have enough contiguous free space for the allocation? */

	longest = xfs_alloc_longest_free_extent(args->mp, pag, min_free);

	longest = xfs_alloc_longest_free_extent(args->mp, pag, min_free,

			reservation);

	if ((args->minlen + args->alignment + args->minalignslop - 1) > longest)

		return false;

	/* do have enough free space remaining for the allocation? */

	/* do we have enough free space remaining for the allocation? */

	available = (int)(pag->pagf_freeblks + pag->pagf_flcount -

			  min_free - args->total);

	if (available < (int)args->minleft)

			  reservation - min_free - args->total);

	if (available < (int)args->minleft || available <= 0)

		return false;

	return true;

		if (error)

			goto out_agbp_relse;

		error = xfs_free_ag_extent(tp, agbp, args->agno, bno, 1,

					   &targs.oinfo, 1);

					   &targs.oinfo, XFS_AG_RESV_AGFL);

		if (error)

			goto out_agbp_relse;

		bp = xfs_btree_get_bufs(mp, tp, args->agno, bno, 0);

	targs.mp = mp;

	targs.agbp = agbp;

	targs.agno = args->agno;

	targs.alignment = targs.minlen = targs.prod = targs.isfl = 1;

	targs.alignment = targs.minlen = targs.prod = 1;

	targs.type = XFS_ALLOCTYPE_THIS_AG;

	targs.pag = pag;

	error = xfs_alloc_read_agfl(mp, tp, targs.agno, &agflbp);

	while (pag->pagf_flcount < need) {

		targs.agbno = 0;

		targs.maxlen = need - pag->pagf_flcount;

		targs.resv = XFS_AG_RESV_AGFL;

		/* Allocate as many blocks as possible at once. */

		error = xfs_alloc_ag_vextent(&targs);

	struct xfs_trans	*tp,	/* transaction pointer */

	xfs_fsblock_t		bno,	/* starting block number of extent */

	xfs_extlen_t		len,	/* length of extent */

	struct xfs_owner_info	*oinfo)	/* extent owner */

	struct xfs_owner_info	*oinfo,	/* extent owner */

	enum xfs_ag_resv_type	type)	/* block reservation type */

{

	struct xfs_mount	*mp = tp->t_mountp;

	struct xfs_buf		*agbp;

	int			error;

	ASSERT(len != 0);

	ASSERT(type != XFS_AG_RESV_AGFL);

	if (XFS_TEST_ERROR(false, mp,

			XFS_ERRTAG_FREE_EXTENT,

		agbno + len <= be32_to_cpu(XFS_BUF_TO_AGF(agbp)->agf_length),

				err);

	error = xfs_free_ag_extent(tp, agbp, agno, agbno, len, oinfo, 0);

	error = xfs_free_ag_extent(tp, agbp, agno, agbno, len, oinfo, type);

	if (error)

		goto err;

	xfs_alloctype_t	otype;		/* original allocation type */

	char		wasdel;		/* set if allocation was prev delayed */

	char		wasfromfl;	/* set if allocation is from freelist */

	char		isfl;		/* set if is freelist blocks - !acctg */

	char		userdata;	/* mask defining userdata treatment */

	xfs_fsblock_t	firstblock;	/* io first block allocated */

	struct xfs_owner_info	oinfo;	/* owner of blocks being allocated */

	enum xfs_ag_resv_type	resv;	/* block reservation to use */

} xfs_alloc_arg_t;

/*

unsigned int xfs_alloc_ag_max_usable(struct xfs_mount *mp);

xfs_extlen_t xfs_alloc_longest_free_extent(struct xfs_mount *mp,

		struct xfs_perag *pag, xfs_extlen_t need);

		struct xfs_perag *pag, xfs_extlen_t need,

		xfs_extlen_t reserved);

unsigned int xfs_alloc_min_freelist(struct xfs_mount *mp,

		struct xfs_perag *pag);