From 41c4c41cf6c44f98db2916e1781f537d9ba6461a Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 14 Sep 2026 22:37:20 -0700 Subject: [PATCH] xfs: fix rtgroup repair estimations When I added online fsck for realtime reflink, I forgot to update xrep_calc_rtgroup_resblks to factor in the size of the refcount btree when it guesses how much space we need to start a repair. This hasn't been a huge problem in practice because there are few filesystems with (a) realtime, (b) rtgroups, (c) reflink, and (d) no rmap. But let's fix this before someone stumbles upon it, especially since LOLLM flagged this for me. Cc: stable@vger.kernel.org # v6.14 Fixes: 83ccffc489975d ("xfs: online repair of the realtime refcount btree") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino --- fs/xfs/scrub/repair.c | 21 ++++++++++++++++++--- fs/xfs/scrub/trace.h | 12 ++++++++---- 2 files changed, 26 insertions(+), 7 deletions(-) diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c index 11697a8b2a1d..c2a437416227 100644 --- a/fs/xfs/scrub/repair.c +++ b/fs/xfs/scrub/repair.c @@ -399,6 +399,7 @@ xrep_calc_rtgroup_resblks( struct xfs_mount *mp = sc->mp; struct xfs_scrub_metadata *sm = sc->sm; uint64_t usedlen; + xfs_extlen_t refcbt_sz = 0; xfs_extlen_t rmapbt_sz = 0; if (!(sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)) @@ -411,13 +412,27 @@ xrep_calc_rtgroup_resblks( usedlen = xfs_rtbxlen_to_blen(mp, xfs_rtgroup_extents(mp, sm->sm_agno)); ASSERT(usedlen <= XFS_MAX_RGBLOCKS); + if (xfs_has_reflink(mp)) + refcbt_sz = xfs_rtrefcountbt_calc_size(mp, usedlen); + if (xfs_has_rmapbt(mp)) rmapbt_sz = xfs_rtrmapbt_calc_size(mp, usedlen); - trace_xrep_calc_rtgroup_resblks_btsize(mp, sm->sm_agno, usedlen, - rmapbt_sz); + /* + * Guess how many blocks we need to rebuild the rmapbt. For + * non-reflink filesystems we can't have more records than used blocks. + * However, with reflink it's possible to have more than one rmap + * record per rtgroup block. We don't know how many rmaps there could + * be in the rtgroup, so we start off with what we hope is an generous + * over-estimation. + */ + if (refcbt_sz > 0 && rmapbt_sz > 0) + rmapbt_sz *= 2; - return rmapbt_sz; + trace_xrep_calc_rtgroup_resblks_btsize(mp, sm->sm_agno, usedlen, + rmapbt_sz, refcbt_sz); + + return max(rmapbt_sz, refcbt_sz); } #endif /* CONFIG_XFS_RT */ diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h index 0f5adc293962..cb85f75ce101 100644 --- a/fs/xfs/scrub/trace.h +++ b/fs/xfs/scrub/trace.h @@ -2376,25 +2376,29 @@ TRACE_EVENT(xrep_calc_ag_resblks_btsize, #ifdef CONFIG_XFS_RT TRACE_EVENT(xrep_calc_rtgroup_resblks_btsize, TP_PROTO(struct xfs_mount *mp, xfs_rgnumber_t rgno, - xfs_rgblock_t usedlen, xfs_rgblock_t rmapbt_sz), - TP_ARGS(mp, rgno, usedlen, rmapbt_sz), + xfs_rgblock_t usedlen, xfs_rgblock_t rmapbt_sz, + xfs_rgblock_t refcbt_sz), + TP_ARGS(mp, rgno, usedlen, rmapbt_sz, refcbt_sz), TP_STRUCT__entry( __field(dev_t, dev) __field(xfs_rgnumber_t, rgno) __field(xfs_rgblock_t, usedlen) __field(xfs_rgblock_t, rmapbt_sz) + __field(xfs_rgblock_t, refcbt_sz) ), TP_fast_assign( __entry->dev = mp->m_super->s_dev; __entry->rgno = rgno; __entry->usedlen = usedlen; __entry->rmapbt_sz = rmapbt_sz; + __entry->refcbt_sz = refcbt_sz; ), - TP_printk("dev %d:%d rgno 0x%x usedlen %u rmapbt %u", + TP_printk("dev %d:%d rgno 0x%x usedlen %u rmapbt %u refcountbt %u", MAJOR(__entry->dev), MINOR(__entry->dev), __entry->rgno, __entry->usedlen, - __entry->rmapbt_sz) + __entry->rmapbt_sz, + __entry->refcbt_sz) ); #endif /* CONFIG_XFS_RT */