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xfs: support shrinking unused space in the last AG

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As the first step of shrinking, this attempts to enable shrinking
unused space in the last allocation group by fixing up freespace
btree, agi, agf and adjusting super block and use a helper
xfs_ag_shrink_space() to fixup the last AG.

This can be all done in one transaction for now, so I think no
additional protection is needed.

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 19:05:39 -07:00 committed by Darrick J. Wong
parent 46141dc891
commit fb2fc17201
2 changed files with 59 additions and 35 deletions
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93
fs/xfs/xfs_fsops.c
View File

@ -91,23 +91,25 @@ xfs_growfs_data_private(
xfs_agnumber_t nagcount;
xfs_agnumber_t nagimax = 0;
xfs_rfsblock_t nb, nb_div, nb_mod;
xfs_rfsblock_t delta;
int64_t delta;
bool lastag_extended;
xfs_agnumber_t oagcount;
struct xfs_trans *tp;
struct aghdr_init_data id = {};
nb = in->newblocks;
if (nb < mp->m_sb.sb_dblocks)
return -EINVAL;
if ((error = xfs_sb_validate_fsb_count(&mp->m_sb, nb)))
return error;
error = xfs_buf_read_uncached(mp->m_ddev_targp,
XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
error = xfs_sb_validate_fsb_count(&mp->m_sb, nb);
if (error)
return error;
xfs_buf_relse(bp);
if (nb > mp->m_sb.sb_dblocks) {
error = xfs_buf_read_uncached(mp->m_ddev_targp,
XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
if (error)
return error;
xfs_buf_relse(bp);
}
nb_div = nb;
nb_mod = do_div(nb_div, mp->m_sb.sb_agblocks);
@ -115,10 +117,16 @@ xfs_growfs_data_private(
if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) {
nagcount--;
nb = (xfs_rfsblock_t)nagcount * mp->m_sb.sb_agblocks;
if (nb < mp->m_sb.sb_dblocks)
return -EINVAL;
}
delta = nb - mp->m_sb.sb_dblocks;
/*
* Reject filesystems with a single AG because they are not
* supported, and reject a shrink operation that would cause a
* filesystem to become unsupported.
*/
if (delta < 0 && nagcount < 2)
return -EINVAL;
oagcount = mp->m_sb.sb_agcount;
/* allocate the new per-ag structures */
@ -126,15 +134,31 @@ xfs_growfs_data_private(
error = xfs_initialize_perag(mp, nagcount, &nagimax);
if (error)
return error;
} else if (nagcount < oagcount) {
/* TODO: shrinking the entire AGs hasn't yet completed */
return -EINVAL;
}
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata,
XFS_GROWFS_SPACE_RES(mp), 0, XFS_TRANS_RESERVE, &tp);
(delta > 0 ? XFS_GROWFS_SPACE_RES(mp) : -delta), 0,
XFS_TRANS_RESERVE, &tp);
if (error)
return error;
error = xfs_resizefs_init_new_ags(tp, &id, oagcount, nagcount,
delta, &lastag_extended);
if (delta > 0) {
error = xfs_resizefs_init_new_ags(tp, &id, oagcount, nagcount,
delta, &lastag_extended);
} else {
static struct ratelimit_state shrink_warning = \
RATELIMIT_STATE_INIT("shrink_warning", 86400 * HZ, 1);
ratelimit_set_flags(&shrink_warning, RATELIMIT_MSG_ON_RELEASE);
if (__ratelimit(&shrink_warning))
xfs_alert(mp,
"EXPERIMENTAL online shrink feature in use. Use at your own risk!");
error = xfs_ag_shrink_space(mp, &tp, nagcount - 1, -delta);
}
if (error)
goto out_trans_cancel;
@ -169,28 +193,29 @@ xfs_growfs_data_private(
xfs_set_low_space_thresholds(mp);
mp->m_alloc_set_aside = xfs_alloc_set_aside(mp);
/*
* If we expanded the last AG, free the per-AG reservation
* so we can reinitialize it with the new size.
*/
if (lastag_extended) {
struct xfs_perag *pag;
if (delta > 0) {
/*
* If we expanded the last AG, free the per-AG reservation
* so we can reinitialize it with the new size.
*/
if (lastag_extended) {
struct xfs_perag *pag;
pag = xfs_perag_get(mp, id.agno);
error = xfs_ag_resv_free(pag);
xfs_perag_put(pag);
if (error)
return error;
pag = xfs_perag_get(mp, id.agno);
error = xfs_ag_resv_free(pag);
xfs_perag_put(pag);
if (error)
return error;
}
/*
* Reserve AG metadata blocks. ENOSPC here does not mean there
* was a growfs failure, just that there still isn't space for
* new user data after the grow has been run.
*/
error = xfs_fs_reserve_ag_blocks(mp);
if (error == -ENOSPC)
error = 0;
}
/*
* Reserve AG metadata blocks. ENOSPC here does not mean there was a
* growfs failure, just that there still isn't space for new user data
* after the grow has been run.
*/
error = xfs_fs_reserve_ag_blocks(mp);
if (error == -ENOSPC)
error = 0;
return error;
out_trans_cancel:

1
fs/xfs/xfs_trans.c
View File

@ -436,7 +436,6 @@ xfs_trans_mod_sb(
tp->t_res_frextents_delta += delta;
break;
case XFS_TRANS_SB_DBLOCKS:
ASSERT(delta > 0);
tp->t_dblocks_delta += delta;
break;
case XFS_TRANS_SB_AGCOUNT: