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bcachefs: Move btree node merging to before transaction commit

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Currently, BTREE_INSERT_NOUNLOCK makes it hard to ensure btree node
merging happens reliably - since btree node merging happens after
transaction commit, we can't drop btree locks and block when starting
the btree update.

This patch moves it to before transaction commit - and failure to do a
merge that we wanted to do just restarts the transaction.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2021-03-29 01:13:31 -04:00 committed by Kent Overstreet
parent ecab6be7e5
commit b182ff609f
1 changed files with 61 additions and 17 deletions
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78
fs/bcachefs/btree_update_leaf.c
View File

@ -492,20 +492,75 @@ err:
return ret;
}
static noinline int maybe_do_btree_merge(struct btree_trans *trans, struct btree_iter *iter)
{
struct btree_insert_entry *i;
struct btree *b = iter_l(iter)->b;
struct bkey_s_c old;
int u64s_delta = 0;
int ret;
/*
* Inserting directly into interior nodes is an uncommon operation with
* various weird edge cases: also, a lot of things about
* BTREE_ITER_NODES iters need to be audited
*/
if (unlikely(btree_iter_type(iter) != BTREE_ITER_KEYS))
return 0;
BUG_ON(iter->level);
trans_for_each_update2(trans, i) {
if (iter_l(i->iter)->b != b)
continue;
old = bch2_btree_iter_peek_slot(i->iter);
ret = bkey_err(old);
if (ret)
return ret;
u64s_delta += !bkey_deleted(&i->k->k) ? i->k->k.u64s : 0;
u64s_delta -= !bkey_deleted(old.k) ? old.k->u64s : 0;
}
return u64s_delta <= 0
? (bch2_foreground_maybe_merge(trans->c, iter, iter->level,
trans->flags & ~BTREE_INSERT_NOUNLOCK) ?: -EINTR)
: 0;
}
/*
* Get journal reservation, take write locks, and attempt to do btree update(s):
*/
static inline int do_bch2_trans_commit(struct btree_trans *trans,
struct btree_insert_entry **stopped_at)
{
struct bch_fs *c = trans->c;
struct btree_insert_entry *i;
struct btree_iter *iter;
int ret;
trans_for_each_update2(trans, i)
BUG_ON(!btree_node_intent_locked(i->iter, i->iter->level));
trans_for_each_update2(trans, i) {
struct btree *b;
ret = bch2_journal_preres_get(&trans->c->journal,
BUG_ON(!btree_node_intent_locked(i->iter, i->level));
if (btree_iter_type(i->iter) == BTREE_ITER_CACHED)
continue;
b = iter_l(i->iter)->b;
if (b->sib_u64s[0] < c->btree_foreground_merge_threshold ||
b->sib_u64s[1] < c->btree_foreground_merge_threshold) {
ret = maybe_do_btree_merge(trans, i->iter);
if (unlikely(ret))
return ret;
}
}
trans_for_each_update2(trans, i)
BUG_ON(!btree_node_intent_locked(i->iter, i->level));
ret = bch2_journal_preres_get(&c->journal,
&trans->journal_preres, trans->journal_preres_u64s,
JOURNAL_RES_GET_NONBLOCK|
((trans->flags & BTREE_INSERT_JOURNAL_RECLAIM)
@ -547,7 +602,7 @@ static inline int do_bch2_trans_commit(struct btree_trans *trans,
trans_for_each_update2(trans, i)
if (!same_leaf_as_prev(trans, i))
bch2_btree_node_lock_for_insert(trans->c,
bch2_btree_node_lock_for_insert(c,
iter_l(i->iter)->b, i->iter);
ret = bch2_trans_commit_write_locked(trans, stopped_at);
@ -558,29 +613,18 @@ static inline int do_bch2_trans_commit(struct btree_trans *trans,
i->iter);
if (!ret && trans->journal_pin)
bch2_journal_pin_add(&trans->c->journal, trans->journal_res.seq,
bch2_journal_pin_add(&c->journal, trans->journal_res.seq,
trans->journal_pin, NULL);
/*
* Drop journal reservation after dropping write locks, since dropping
* the journal reservation may kick off a journal write:
*/
bch2_journal_res_put(&trans->c->journal, &trans->journal_res);
bch2_journal_res_put(&c->journal, &trans->journal_res);
if (unlikely(ret))
return ret;
if (trans->flags & BTREE_INSERT_NOUNLOCK)
trans->nounlock = true;
trans_for_each_update2(trans, i)
if (btree_iter_type(i->iter) != BTREE_ITER_CACHED &&
!same_leaf_as_prev(trans, i))
bch2_foreground_maybe_merge(trans->c, i->iter,
0, trans->flags);
trans->nounlock = false;
bch2_trans_downgrade(trans);
return 0;