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bcachefs: bch2_trans_revalidate_updates_in_node()

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When we started stashing the key being overwritten in
btree_insert_entry, this introduced a typical iterator invalidation
problem, triggered by btree node splits or resorts.

Previously, dealt with this by unconditionally re-validating those
stashed pointers in the transaction commit path. This patch gets rid of
that by doing it only when needed, in bch2_trans_node_add() or
bch2_trans_node_reinit_iter().

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2022-11-23 18:46:03 -05:00
parent 321bdc73f3
commit 08f7803159
2 changed files with 63 additions and 27 deletions
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30
fs/bcachefs/btree_iter.c
View file

@ -652,6 +652,32 @@ void bch2_btree_path_level_init(struct btree_trans *trans,
/* Btree path: fixups after btree node updates: */
static void bch2_trans_revalidate_updates_in_node(struct btree_trans *trans, struct btree *b)
{
struct bch_fs *c = trans->c;
struct btree_insert_entry *i;
trans_for_each_update(trans, i)
if (!i->cached &&
i->level == b->c.level &&
i->btree_id == b->c.btree_id &&
bpos_cmp(i->k->k.p, b->data->min_key) >= 0 &&
bpos_cmp(i->k->k.p, b->data->max_key) <= 0) {
i->old_v = bch2_btree_path_peek_slot(i->path, &i->old_k).v;
if (unlikely(trans->journal_replay_not_finished)) {
struct bkey_i *j_k =
bch2_journal_keys_peek_slot(c, i->btree_id, i->level,
i->k->k.p);
if (j_k) {
i->old_k = j_k->k;
i->old_v = &j_k->v;
}
}
}
}
/*
* A btree node is being replaced - update the iterator to point to the new
* node:
@ -675,6 +701,8 @@ void bch2_trans_node_add(struct btree_trans *trans, struct btree *b)
bch2_btree_path_level_init(trans, path, b);
}
bch2_trans_revalidate_updates_in_node(trans, b);
}
/*
@ -687,6 +715,8 @@ void bch2_trans_node_reinit_iter(struct btree_trans *trans, struct btree *b)
trans_for_each_path_with_node(trans, b, path)
__btree_path_level_init(path, b->c.level);
bch2_trans_revalidate_updates_in_node(trans, b);
}
/* Btree path: traverse, set_pos: */

60
fs/bcachefs/btree_update_leaf.c
View file

@ -40,6 +40,28 @@ struct bkey_s_c bch2_btree_path_peek_slot_exact(struct btree_path *path, struct
return (struct bkey_s_c) { u, NULL };
}
static void verify_update_old_key(struct btree_trans *trans, struct btree_insert_entry *i)
{
#ifdef CONFIG_BCACHEFS_DEBUG
struct bch_fs *c = trans->c;
struct bkey u;
struct bkey_s_c k = bch2_btree_path_peek_slot_exact(i->path, &u);
if (unlikely(trans->journal_replay_not_finished)) {
struct bkey_i *j_k =
bch2_journal_keys_peek_slot(c, i->btree_id, i->level, i->k->k.p);
if (j_k)
k = bkey_i_to_s_c(j_k);
}
i->old_k.needs_whiteout = k.k->needs_whiteout;
BUG_ON(memcmp(&i->old_k, k.k, sizeof(struct bkey)));
BUG_ON(i->old_v != k.v);
#endif
}
static int __must_check
bch2_trans_update_by_path(struct btree_trans *, struct btree_path *,
struct bkey_i *, enum btree_update_flags);
@ -354,6 +376,7 @@ static int btree_key_can_insert_cached(struct btree_trans *trans,
{
struct bch_fs *c = trans->c;
struct bkey_cached *ck = (void *) path->l[0].b;
struct btree_insert_entry *i;
unsigned new_u64s;
struct bkey_i *new_k;
@ -381,6 +404,10 @@ static int btree_key_can_insert_cached(struct btree_trans *trans,
return -ENOMEM;
}
trans_for_each_update(trans, i)
if (i->old_v == &ck->k->v)
i->old_v = &new_k->v;
ck->u64s = new_u64s;
ck->k = new_k;
return 0;
@ -396,6 +423,8 @@ static int run_one_mem_trigger(struct btree_trans *trans,
struct bkey_i *new = i->k;
int ret;
verify_update_old_key(trans, i);
if (unlikely(flags & BTREE_TRIGGER_NORUN))
return 0;
@ -433,6 +462,8 @@ static int run_one_trans_trigger(struct btree_trans *trans, struct btree_insert_
struct bkey old_k = i->old_k;
struct bkey_s_c old = { &old_k, i->old_v };
verify_update_old_key(trans, i);
if ((i->flags & BTREE_TRIGGER_NORUN) ||
!(BTREE_NODE_TYPE_HAS_TRANS_TRIGGERS & (1U << i->bkey_type)))
return 0;
@ -611,33 +642,6 @@ bch2_trans_commit_write_locked(struct btree_trans *trans,
if (btree_node_type_needs_gc(i->bkey_type))
marking = true;
/*
* Revalidate before calling mem triggers - XXX, ugly:
*
* - successful btree node splits don't cause transaction
* restarts and will have invalidated the pointer to the bkey
* value
* - btree_node_lock_for_insert() -> btree_node_prep_for_write()
* when it has to resort
* - btree_key_can_insert_cached() when it has to reallocate
*
* Ugly because we currently have no way to tell if the
* pointer's been invalidated, which means it's debatabale
* whether we should be stashing the old key at all.
*/
i->old_v = bch2_btree_path_peek_slot(i->path, &i->old_k).v;
if (unlikely(trans->journal_replay_not_finished)) {
struct bkey_i *j_k =
bch2_journal_keys_peek_slot(c, i->btree_id, i->level,
i->k->k.p);
if (j_k) {
i->old_k = j_k->k;
i->old_v = &j_k->v;
}
}
}
/*
@ -707,6 +711,8 @@ bch2_trans_commit_write_locked(struct btree_trans *trans,
if (i->flags & BTREE_UPDATE_NOJOURNAL)
continue;
verify_update_old_key(trans, i);
if (trans->journal_transaction_names) {
entry = bch2_journal_add_entry(j, &trans->journal_res,
BCH_JSET_ENTRY_overwrite,