bcachefs: Tighten up btree_iter locking assertions

We weren't correctly verifying that we had interior node intent locks -
this patch also fixes bugs uncovered by the new assertions.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

diff --git a/fs/bcachefs/btree_cache.c b/fs/bcachefs/btree_cache.c
index 430d5951263f551ef1caafc65e5c2c5bec89808c..19afbdcae5e48c55ae00e5ac06176476e199b108 100644 (file)
--- a/fs/bcachefs/btree_cache.c
+++ b/fs/bcachefs/btree_cache.c
@@ -698,7 +698,9 @@ static noinline struct btree *bch2_btree_node_fill(struct bch_fs *c,
         * currently fails for iterators that aren't pointed at a valid btree
         * node
         */
-       if (iter && !bch2_trans_relock(iter->trans))
+       if (iter &&
+           (!bch2_trans_relock(iter->trans) ||
+            !bch2_btree_iter_relock(iter, _THIS_IP_)))
                return ERR_PTR(-EINTR);
 
        if (!six_relock_type(&b->c.lock, lock_type, seq))
@@ -858,7 +860,9 @@ lock_node:
                 * currently fails for iterators that aren't pointed at a valid
                 * btree node
                 */
-               if (iter && !bch2_trans_relock(iter->trans))
+               if (iter &&
+                   (!bch2_trans_relock(iter->trans) ||
+                    !bch2_btree_iter_relock(iter, _THIS_IP_)))
                        return ERR_PTR(-EINTR);
 
                if (!six_relock_type(&b->c.lock, lock_type, seq))

diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index 13e4dea8a09b9a32564d922db3b391a0c6b30f98..22419929ac1b71dfbbb5c563bbaf6901e30b4bf4 100644 (file)
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -361,7 +361,7 @@ static void bch2_btree_iter_verify_locks(struct btree_iter *iter)
                return;
        }
 
-       for (l = 0; is_btree_node(iter, l); l++) {
+       for (l = 0; btree_iter_node(iter, l); l++) {
                if (iter->uptodate >= BTREE_ITER_NEED_RELOCK &&
                    !btree_node_locked(iter, l))
                        continue;
@@ -383,7 +383,7 @@ static inline void bch2_btree_iter_verify_locks(struct btree_iter *iter) {}
 #endif
 
 __flatten
-static bool bch2_btree_iter_relock(struct btree_iter *iter, unsigned long trace_ip)
+bool bch2_btree_iter_relock(struct btree_iter *iter, unsigned long trace_ip)
 {
        return btree_iter_get_locks(iter, false, trace_ip);
 }
@@ -607,6 +607,8 @@ err:
 
 static void bch2_btree_iter_verify(struct btree_iter *iter)
 {
+       struct btree_trans *trans = iter->trans;
+       struct bch_fs *c = trans->c;
        enum btree_iter_type type = btree_iter_type(iter);
        unsigned i;
 
@@ -625,10 +627,16 @@ static void bch2_btree_iter_verify(struct btree_iter *iter)
               (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
               !btree_type_has_snapshots(iter->btree_id));
 
-       bch2_btree_iter_verify_locks(iter);
+       for (i = 0; i < (type != BTREE_ITER_CACHED ? BTREE_MAX_DEPTH : 1); i++) {
+               if (!iter->l[i].b) {
+                       BUG_ON(c->btree_roots[iter->btree_id].b->c.level > i);
+                       break;
+               }
 
-       for (i = 0; i < BTREE_MAX_DEPTH; i++)
                bch2_btree_iter_verify_level(iter, i);
+       }
+
+       bch2_btree_iter_verify_locks(iter);
 }
 
 static void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter)
@@ -1350,30 +1358,30 @@ static inline unsigned btree_iter_up_until_good_node(struct btree_iter *iter,
 static int btree_iter_traverse_one(struct btree_iter *iter,
                                   unsigned long trace_ip)
 {
-       unsigned depth_want = iter->level;
+       unsigned l, depth_want = iter->level;
        int ret = 0;
 
-       /*
-        * if we need interior nodes locked, call btree_iter_relock() to make
-        * sure we walk back up enough that we lock them:
-        */
-       if (iter->uptodate == BTREE_ITER_NEED_RELOCK ||
-           iter->locks_want > 1)
-               bch2_btree_iter_relock(iter, _THIS_IP_);
-
        if (btree_iter_type(iter) == BTREE_ITER_CACHED) {
                ret = bch2_btree_iter_traverse_cached(iter);
                goto out;
        }
 
-       if (iter->uptodate < BTREE_ITER_NEED_RELOCK)
-               goto out;
-
        if (unlikely(iter->level >= BTREE_MAX_DEPTH))
                goto out;
 
        iter->level = btree_iter_up_until_good_node(iter, 0);
 
+       /* If we need intent locks, take them too: */
+       for (l = iter->level + 1;
+            l < iter->locks_want && btree_iter_node(iter, l);
+            l++)
+               if (!bch2_btree_node_relock(iter, l))
+                       while (iter->level <= l) {
+                               btree_node_unlock(iter, iter->level);
+                               iter->l[iter->level].b = BTREE_ITER_NO_NODE_UP;
+                               iter->level++;
+                       }
+
        /*
         * Note: iter->nodes[iter->level] may be temporarily NULL here - that
         * would indicate to other code that we got to the end of the btree,
@@ -1394,6 +1402,7 @@ static int btree_iter_traverse_one(struct btree_iter *iter,
                                goto out;
                        }
 
+                       __bch2_btree_iter_unlock(iter);
                        iter->level = depth_want;
 
                        if (ret == -EIO) {

diff --git a/fs/bcachefs/btree_iter.h b/fs/bcachefs/btree_iter.h
index 31175cf00c0a163e39739598e9acd7939e513857..58f15b716d49128a15c4a9c24c030edda709c1b7 100644 (file)
--- a/fs/bcachefs/btree_iter.h
+++ b/fs/bcachefs/btree_iter.h
@@ -111,6 +111,8 @@ void bch2_btree_node_iter_fix(struct btree_iter *, struct btree *,
                              struct btree_node_iter *, struct bkey_packed *,
                              unsigned, unsigned);
 
+bool bch2_btree_iter_relock(struct btree_iter *, unsigned long);
+
 bool bch2_trans_relock(struct btree_trans *);
 void bch2_trans_unlock(struct btree_trans *);
 

diff --git a/fs/bcachefs/btree_key_cache.c b/fs/bcachefs/btree_key_cache.c
index bafa1f0abc885aace97aeeb837647528798ee94f..d60b6084fdf088d9d21c3706f4668d71a0bb7f39 100644 (file)
--- a/fs/bcachefs/btree_key_cache.c
+++ b/fs/bcachefs/btree_key_cache.c
@@ -271,7 +271,9 @@ int bch2_btree_iter_traverse_cached(struct btree_iter *iter)
 
        BUG_ON(iter->level);
 
-       if (btree_node_locked(iter, 0)) {
+       iter->l[1].b = NULL;
+
+       if (bch2_btree_node_relock(iter, 0)) {
                ck = (void *) iter->l[0].b;
                goto fill;
        }