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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: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
This commit is contained in:
Gao Xiang 2021-03-23 19:05:38 -07:00 committed by Darrick J. Wong
parent c789c83c7e
commit 46141dc891
2 changed files with 117 additions and 0 deletions
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115
fs/xfs/libxfs/xfs_ag.c
View File

@ -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
*/

2
fs/xfs/libxfs/xfs_ag.h
View File

@ -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,