From c0889ee7613ca64aa1fb2ff767e59074f04e8176 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Tue, 28 May 2024 21:12:51 -0700 Subject: [PATCH] xfs: allow queued realtime intents to drain before scrubbing When a writer thread executes a chain of log intent items for the realtime volume, the ILOCKs taken during each step are for each rt metadata file, not the entire rt volume itself. Although scrub takes all rt metadata ILOCKs, this isn't sufficient to guard against scrub checking the rt volume while that writer thread is in the middle of finishing a chain because there's no higher level locking primitive guarding the realtime volume. When there's a collision, cross-referencing between data structures (e.g. rtrmapbt and rtrefcountbt) yields false corruption events; if repair is running, this results in incorrect repairs, which is catastrophic. Fix this by adding to the mount structure the same drain that we use to protect scrub against concurrent AG updates, but this time for the realtime volume. [Contains a few cleanups from hch] Cc: Christoph Hellwig Signed-off-by: Darrick J. Wong --- include/xfs_mount.h | 12 ++++++++++++ libxfs/defer_item.c | 31 +++++++++++++------------------ libxfs/xfs_rtgroup.c | 7 +++++++ libxfs/xfs_rtgroup.h | 9 +++++++++ 4 files changed, 41 insertions(+), 18 deletions(-) diff --git a/include/xfs_mount.h b/include/xfs_mount.h index 8ef5fcc2c..f78f0d050 100644 --- a/include/xfs_mount.h +++ b/include/xfs_mount.h @@ -333,6 +333,18 @@ struct xfs_defer_drain { /* empty */ }; static inline void xfs_perag_intent_hold(struct xfs_perag *pag) {} static inline void xfs_perag_intent_rele(struct xfs_perag *pag) {} +struct xfs_rtgroup; + +#define xfs_rtgroup_intent_get(mp, rgno) \ + xfs_rtgroup_get((mp), xfs_rtb_to_rgno((mp), (rgno))) +#define xfs_rtgroup_intent_put(rtg) xfs_rtgroup_put(rtg) + +static inline void xfs_rtgroup_intent_hold(struct xfs_rtgroup *rtg) { } +static inline void xfs_rtgroup_intent_rele(struct xfs_rtgroup *rtg) { } + +#define xfs_drain_free(dr) ((void)0) +#define xfs_drain_init(dr) ((void)0) + static inline void libxfs_buftarg_drain(struct xfs_buftarg *btp) { cache_purge(btp->bcache); diff --git a/libxfs/defer_item.c b/libxfs/defer_item.c index 658e6d608..e748ce8b9 100644 --- a/libxfs/defer_item.c +++ b/libxfs/defer_item.c @@ -87,11 +87,8 @@ xfs_extent_free_defer_add( struct xfs_mount *mp = tp->t_mountp; if (xfs_efi_is_realtime(xefi)) { - xfs_rgnumber_t rgno; - - rgno = xfs_rtb_to_rgno(mp, xefi->xefi_startblock); - xefi->xefi_rtg = xfs_rtgroup_get(mp, rgno); - + xefi->xefi_rtg = xfs_rtgroup_intent_get(mp, + xefi->xefi_startblock); *dfpp = xfs_defer_add(tp, &xefi->xefi_list, &xfs_rtextent_free_defer_type); return; @@ -203,7 +200,7 @@ xfs_rtextent_free_cancel_item( { struct xfs_extent_free_item *xefi = xefi_entry(item); - xfs_rtgroup_put(xefi->xefi_rtg); + xfs_rtgroup_intent_put(xefi->xefi_rtg); kmem_cache_free(xfs_extfree_item_cache, xefi); } @@ -337,13 +334,12 @@ xfs_rmap_defer_add( * section updates. */ if (ri->ri_realtime) { - xfs_rgnumber_t rgno; - - rgno = xfs_rtb_to_rgno(mp, ri->ri_bmap.br_startblock); - ri->ri_rtg = xfs_rtgroup_get(mp, rgno); + ri->ri_rtg = xfs_rtgroup_intent_get(mp, + ri->ri_bmap.br_startblock); xfs_defer_add(tp, &ri->ri_list, &xfs_rtrmap_update_defer_type); } else { - ri->ri_pag = xfs_perag_intent_get(mp, ri->ri_bmap.br_startblock); + ri->ri_pag = xfs_perag_intent_get(mp, + ri->ri_bmap.br_startblock); xfs_defer_add(tp, &ri->ri_list, &xfs_rmap_update_defer_type); } } @@ -444,7 +440,7 @@ xfs_rtrmap_update_cancel_item( { struct xfs_rmap_intent *ri = ri_entry(item); - xfs_rtgroup_put(ri->ri_rtg); + xfs_rtgroup_intent_put(ri->ri_rtg); kmem_cache_free(xfs_rmap_intent_cache, ri); } @@ -667,10 +663,8 @@ xfs_bmap_update_get_group( { if (xfs_ifork_is_realtime(bi->bi_owner, bi->bi_whichfork)) { if (xfs_has_rtgroups(mp)) { - xfs_rgnumber_t rgno; - - rgno = xfs_rtb_to_rgno(mp, bi->bi_bmap.br_startblock); - bi->bi_rtg = xfs_rtgroup_get(mp, rgno); + bi->bi_rtg = xfs_rtgroup_intent_get(mp, + bi->bi_bmap.br_startblock); } else { bi->bi_rtg = NULL; } @@ -706,8 +700,9 @@ xfs_bmap_update_put_group( struct xfs_bmap_intent *bi) { if (xfs_ifork_is_realtime(bi->bi_owner, bi->bi_whichfork)) { - if (xfs_has_rtgroups(bi->bi_owner->i_mount)) - xfs_rtgroup_put(bi->bi_rtg); + if (xfs_has_rtgroups(bi->bi_owner->i_mount)) { + xfs_rtgroup_intent_put(bi->bi_rtg); + } return; } diff --git a/libxfs/xfs_rtgroup.c b/libxfs/xfs_rtgroup.c index 89a02f741..f58b27102 100644 --- a/libxfs/xfs_rtgroup.c +++ b/libxfs/xfs_rtgroup.c @@ -164,6 +164,7 @@ xfs_initialize_rtgroups( /* Place kernel structure only init below this point. */ spin_lock_init(&rtg->rtg_state_lock); init_waitqueue_head(&rtg->rtg_active_wq); + xfs_defer_drain_init(&rtg->rtg_intents_drain); #endif /* __KERNEL__ */ /* Active ref owned by mount indicates rtgroup is online. */ @@ -203,6 +204,9 @@ xfs_free_unused_rtgroup_range( spin_unlock(&mp->m_rtgroup_lock); if (!rtg) break; +#ifdef __KERNEL__ + xfs_defer_drain_free(&rtg->rtg_intents_drain); +#endif kfree(rtg); } } @@ -236,6 +240,9 @@ xfs_free_rtgroups( spin_unlock(&mp->m_rtgroup_lock); ASSERT(rtg); XFS_IS_CORRUPT(mp, atomic_read(&rtg->rtg_ref) != 0); +#ifdef __KERNEL__ + xfs_defer_drain_free(&rtg->rtg_intents_drain); +#endif /* drop the mount's active reference */ xfs_rtgroup_rele(rtg); diff --git a/libxfs/xfs_rtgroup.h b/libxfs/xfs_rtgroup.h index acd88ae16..f0abe53ef 100644 --- a/libxfs/xfs_rtgroup.h +++ b/libxfs/xfs_rtgroup.h @@ -48,6 +48,15 @@ struct xfs_rtgroup { #ifdef __KERNEL__ /* -- kernel only structures below this line -- */ spinlock_t rtg_state_lock; + + /* + * We use xfs_drain to track the number of deferred log intent items + * that have been queued (but not yet processed) so that waiters (e.g. + * scrub) will not lock resources when other threads are in the middle + * of processing a chain of intent items only to find momentary + * inconsistencies. + */ + struct xfs_defer_drain rtg_intents_drain; #endif /* __KERNEL__ */ }; -- 2.50.1