Commit 46141dc8 authored by Gao Xiang's avatar Gao Xiang Committed by Darrick J. Wong
Browse files

xfs: introduce xfs_ag_shrink_space() 



This patch introduces a helper to shrink unused space in the last AG
by fixing up the freespace btree.

Also make sure that the per-AG reservation works under the new AG
size. If such per-AG reservation or extent allocation fails, roll
the transaction so the new transaction could cancel without any side
effects.

Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarGao Xiang <hsiangkao@redhat.com>
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
parent c789c83c

fs/xfs/libxfs/xfs_ag.c

+115 −0
Original line number Diff line number Diff line
@@ -22,6 +22,11 @@ 
#include "xfs_ag.h"

#include "xfs_ag_resv.h"

#include "xfs_health.h"

#include "xfs_error.h"

#include "xfs_bmap.h"

#include "xfs_defer.h"

#include "xfs_log_format.h"

#include "xfs_trans.h"



static int

xfs_get_aghdr_buf(
@@ -485,6 +490,116 @@ xfs_ag_init_headers( 
	return error;

}



int

xfs_ag_shrink_space(

	struct xfs_mount	*mp,

	struct xfs_trans	**tpp,

	xfs_agnumber_t		agno,

	xfs_extlen_t		delta)

{

	struct xfs_alloc_arg	args = {

		.tp	= *tpp,

		.mp	= mp,

		.type	= XFS_ALLOCTYPE_THIS_BNO,

		.minlen = delta,

		.maxlen = delta,

		.oinfo	= XFS_RMAP_OINFO_SKIP_UPDATE,

		.resv	= XFS_AG_RESV_NONE,

		.prod	= 1

	};

	struct xfs_buf		*agibp, *agfbp;

	struct xfs_agi		*agi;

	struct xfs_agf		*agf;

	int			error, err2;



	ASSERT(agno == mp->m_sb.sb_agcount - 1);

	error = xfs_ialloc_read_agi(mp, *tpp, agno, &agibp);

	if (error)

		return error;



	agi = agibp->b_addr;



	error = xfs_alloc_read_agf(mp, *tpp, agno, 0, &agfbp);

	if (error)

		return error;



	agf = agfbp->b_addr;

	/* some extra paranoid checks before we shrink the ag */

	if (XFS_IS_CORRUPT(mp, agf->agf_length != agi->agi_length))

		return -EFSCORRUPTED;

	if (delta >= agi->agi_length)

		return -EINVAL;



	args.fsbno = XFS_AGB_TO_FSB(mp, agno,

				    be32_to_cpu(agi->agi_length) - delta);



	/*

	 * Disable perag reservations so it doesn't cause the allocation request

	 * to fail. We'll reestablish reservation before we return.

	 */

	error = xfs_ag_resv_free(agibp->b_pag);

	if (error)

		return error;



	/* internal log shouldn't also show up in the free space btrees */

	error = xfs_alloc_vextent(&args);

	if (!error && args.agbno == NULLAGBLOCK)

		error = -ENOSPC;



	if (error) {

		/*

		 * if extent allocation fails, need to roll the transaction to

		 * ensure that the AGFL fixup has been committed anyway.

		 */

		xfs_trans_bhold(*tpp, agfbp);

		err2 = xfs_trans_roll(tpp);

		if (err2)

			return err2;

		xfs_trans_bjoin(*tpp, agfbp);

		goto resv_init_out;

	}



	/*

	 * if successfully deleted from freespace btrees, need to confirm

	 * per-AG reservation works as expected.

	 */

	be32_add_cpu(&agi->agi_length, -delta);

	be32_add_cpu(&agf->agf_length, -delta);



	err2 = xfs_ag_resv_init(agibp->b_pag, *tpp);

	if (err2) {

		be32_add_cpu(&agi->agi_length, delta);

		be32_add_cpu(&agf->agf_length, delta);

		if (err2 != -ENOSPC)

			goto resv_err;



		__xfs_bmap_add_free(*tpp, args.fsbno, delta, NULL, true);



		/*

		 * Roll the transaction before trying to re-init the per-ag

		 * reservation. The new transaction is clean so it will cancel

		 * without any side effects.

		 */

		error = xfs_defer_finish(tpp);

		if (error)

			return error;



		error = -ENOSPC;

		goto resv_init_out;

	}

	xfs_ialloc_log_agi(*tpp, agibp, XFS_AGI_LENGTH);

	xfs_alloc_log_agf(*tpp, agfbp, XFS_AGF_LENGTH);

	return 0;

resv_init_out:

	err2 = xfs_ag_resv_init(agibp->b_pag, *tpp);

	if (!err2)

		return error;

resv_err:

	xfs_warn(mp, "Error %d reserving per-AG metadata reserve pool.", err2);

	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);

	return err2;

}



/*

 * Extent the AG indicated by the @id by the length passed in

 */

fs/xfs/libxfs/xfs_ag.h

+2 −0
Original line number Diff line number Diff line
@@ -24,6 +24,8 @@ struct aghdr_init_data { 
};



int xfs_ag_init_headers(struct xfs_mount *mp, struct aghdr_init_data *id);

int xfs_ag_shrink_space(struct xfs_mount *mp, struct xfs_trans **tpp,

			xfs_agnumber_t agno, xfs_extlen_t delta);

int xfs_ag_extend_space(struct xfs_mount *mp, struct xfs_trans *tp,

			struct aghdr_init_data *id, xfs_extlen_t len);

int xfs_ag_get_geometry(struct xfs_mount *mp, xfs_agnumber_t agno,