From 53413714a49db20f28442c8e2b27b508564bf4fe Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Wed, 17 Jun 2020 17:30:38 -0400 Subject: bcachefs: Fix a deadlock in the RO path Signed-off-by: Kent Overstreet --- fs/bcachefs/btree_gc.c | 9 +++++++-- fs/bcachefs/buckets.c | 5 ++++- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/fs/bcachefs/btree_gc.c b/fs/bcachefs/btree_gc.c index 7293b8fedd27..8771ef1f07cc 100644 --- a/fs/bcachefs/btree_gc.c +++ b/fs/bcachefs/btree_gc.c @@ -930,7 +930,12 @@ int bch2_gc_gens(struct bch_fs *c) unsigned i; int ret; - down_read(&c->state_lock); + /* + * Ideally we would be using state_lock and not gc_lock here, but that + * introduces a deadlock in the RO path - we currently take the state + * lock at the start of going RO, thus the gc thread may get stuck: + */ + down_read(&c->gc_lock); for_each_member_device(ca, c, i) { down_read(&ca->bucket_lock); @@ -957,7 +962,7 @@ int bch2_gc_gens(struct bch_fs *c) up_read(&ca->bucket_lock); } err: - up_read(&c->state_lock); + up_read(&c->gc_lock); return ret; } diff --git a/fs/bcachefs/buckets.c b/fs/bcachefs/buckets.c index a9935cc3df2e..f75edb3c175a 100644 --- a/fs/bcachefs/buckets.c +++ b/fs/bcachefs/buckets.c @@ -2019,6 +2019,7 @@ int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets) bch2_copygc_stop(ca); if (resize) { + down_write(&c->gc_lock); down_write(&ca->bucket_lock); percpu_down_write(&c->mark_lock); } @@ -2041,8 +2042,10 @@ int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets) swap(ca->buckets_nouse, buckets_nouse); - if (resize) + if (resize) { percpu_up_write(&c->mark_lock); + up_write(&c->gc_lock); + } spin_lock(&c->freelist_lock); for (i = 0; i < RESERVE_NR; i++) { -- cgit v1.2.3