bcachefs: Don't call bch2_journal_pin_drop() under key cache lock

This fixes a (harmless) lockdep splat, due to a lock order violation in
the key cache exit path.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/btree_key_cache.c b/fs/bcachefs/btree_key_cache.c
index 743ebeba12b145401d28a80511336a6bfd468b13..867f063f22d13033dc382e61fc49d09e480d829d 100644 (file)
--- a/fs/bcachefs/btree_key_cache.c
+++ b/fs/bcachefs/btree_key_cache.c
@@ -947,6 +947,7 @@ void bch2_fs_btree_key_cache_exit(struct btree_key_cache *bc)
        struct bucket_table *tbl;
        struct bkey_cached *ck, *n;
        struct rhash_head *pos;
+       LIST_HEAD(items);
        unsigned i;
 #ifdef __KERNEL__
        int cpu;
@@ -967,7 +968,7 @@ void bch2_fs_btree_key_cache_exit(struct btree_key_cache *bc)
                        for (i = 0; i < tbl->size; i++)
                                rht_for_each_entry_rcu(ck, pos, tbl, i, hash) {
                                        bkey_cached_evict(bc, ck);
-                                       list_add(&ck->list, &bc->freed_nonpcpu);
+                                       list_add(&ck->list, &items);
                                }
                rcu_read_unlock();
        }
@@ -979,14 +980,17 @@ void bch2_fs_btree_key_cache_exit(struct btree_key_cache *bc)
 
                for (i = 0; i < f->nr; i++) {
                        ck = f->objs[i];
-                       list_add(&ck->list, &bc->freed_nonpcpu);
+                       list_add(&ck->list, &items);
                }
        }
 #endif
 
-       list_splice(&bc->freed_pcpu, &bc->freed_nonpcpu);
+       list_splice(&bc->freed_pcpu,    &items);
+       list_splice(&bc->freed_nonpcpu, &items);
 
-       list_for_each_entry_safe(ck, n, &bc->freed_nonpcpu, list) {
+       mutex_unlock(&bc->lock);
+
+       list_for_each_entry_safe(ck, n, &items, list) {
                cond_resched();
 
                bch2_journal_pin_drop(&c->journal, &ck->journal);
@@ -1008,8 +1012,6 @@ void bch2_fs_btree_key_cache_exit(struct btree_key_cache *bc)
                panic("btree key cache shutdown error: nr_keys nonzero (%li)\n",
                      atomic_long_read(&bc->nr_keys));
 
-       mutex_unlock(&bc->lock);
-
        if (bc->table_init_done)
                rhashtable_destroy(&bc->table);