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.
Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
---
fs/xfs/xfs_fsops.c | 90 ++++++++++++++++++++++++++++------------------
fs/xfs/xfs_trans.c | 1 -
2 files changed, 55 insertions(+), 36 deletions(-)
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 494f9354e3fb..204c96d0010f 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -90,23 +90,29 @@ xfs_growfs_data_private(
int error;
xfs_agnumber_t nagcount;
xfs_agnumber_t nagimax = 0;
- xfs_rfsblock_t nb, nb_div, nb_mod, delta;
+ xfs_rfsblock_t nb, nb_div, nb_mod;
+ int64_t delta;
bool lastag_resetagres;
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)))
+ if (nb == mp->m_sb.sb_dblocks)
+ return 0;
+
+ 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);
@@ -114,10 +120,15 @@ 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;
+ /*
+ * XFS doesn't really support single-AG filesystems, so do not
+ * permit callers to remove the filesystem's second and last AG.
+ */
+ if (delta < 0 && nagcount < 2)
+ return -EINVAL;
+
oagcount = mp->m_sb.sb_agcount;
/* allocate the new per-ag structures */
@@ -125,15 +136,23 @@ 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_resetagres);
+ if (delta > 0)
+ error = xfs_resizefs_init_new_ags(tp, &id, oagcount, nagcount,
+ delta, &lastag_resetagres);
+ else
+ error = xfs_ag_shrink_space(mp, &tp, nagcount - 1, -delta);
+
if (error)
goto out_trans_cancel;
@@ -144,7 +163,7 @@ xfs_growfs_data_private(
*/
if (nagcount > oagcount)
xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
- if (delta > 0)
+ if (delta)
xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS, delta);
if (id.nfree)
xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, id.nfree);
@@ -168,28 +187,29 @@ 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_resetagres) {
- 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_resetagres) {
+ 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 44f72c09c203..d047f5f26cc0 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -434,7 +434,6 @@ 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:
--
2.27.0
