From fb2fc172018599a6564aab4ac0dce79bf94bd6bc Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Tue, 23 Mar 2021 19:05:39 -0700 Subject: [PATCH] xfs: support shrinking unused space in the last AG 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 Signed-off-by: Gao Xiang Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_fsops.c | 93 +++++++++++++++++++++++++++++----------------- fs/xfs/xfs_trans.c | 1 - 2 files changed, 59 insertions(+), 35 deletions(-) diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c index d1ba04124c28..b33c894b6cf3 100644 --- a/fs/xfs/xfs_fsops.c +++ b/fs/xfs/xfs_fsops.c @@ -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))) + error = xfs_sb_validate_fsb_count(&mp->m_sb, nb); + if (error) return error; - error = xfs_buf_read_uncached(mp->m_ddev_targp, + + 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); + 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; - - pag = xfs_perag_get(mp, id.agno); - error = xfs_ag_resv_free(pag); - xfs_perag_put(pag); - if (error) - return error; + 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; + } + /* + * 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: diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c index 631cca73198f..bc25afc10245 100644 --- a/fs/xfs/xfs_trans.c +++ b/fs/xfs/xfs_trans.c @@ -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: -- 2.20.1