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bcachefs: Fix btree_and_journal_iter

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We had a bug where btree_and_journal_iter would return the same key
twice - after deleting it (perhaps because it was present in both the
btree and the journal?)

This reworks btree_and_journal_iter to track the current position, much
like btree_paths, which makes the logic considerably simpler and more
robust.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2022-06-06 21:59:34 -04:00 committed by Kent Overstreet
parent f2aa026575
commit 576179021c
2 changed files with 41 additions and 70 deletions
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102
fs/bcachefs/recovery.c
View File

@ -159,21 +159,17 @@ static void journal_iters_fix(struct bch_fs *c)
{
struct journal_keys *keys = &c->journal_keys;
/* The key we just inserted is immediately before the gap: */
struct journal_key *n = &keys->d[keys->gap - 1];
size_t gap_end = keys->gap + (keys->size - keys->nr);
struct btree_and_journal_iter *iter;
/*
* If an iterator points one after the key we just inserted,
* and the key we just inserted compares > the iterator's position,
* decrement the iterator so it points at the key we just inserted:
* If an iterator points one after the key we just inserted, decrement
* the iterator so it points at the key we just inserted - if the
* decrement was unnecessary, bch2_btree_and_journal_iter_peek() will
* handle that:
*/
list_for_each_entry(iter, &c->journal_iters, journal.list)
if (iter->journal.idx == gap_end &&
iter->last &&
iter->b->c.btree_id == n->btree_id &&
iter->b->c.level == n->level &&
bpos_cmp(n->k->k.p, iter->unpacked.p) > 0)
if (iter->journal.idx == gap_end)
iter->journal.idx = keys->gap - 1;
}
@ -312,7 +308,7 @@ static void bch2_journal_iter_advance(struct journal_iter *iter)
}
}
struct bkey_i *bch2_journal_iter_peek(struct journal_iter *iter)
struct bkey_s_c bch2_journal_iter_peek(struct journal_iter *iter)
{
struct journal_key *k = iter->keys->d + iter->idx;
@ -320,13 +316,13 @@ struct bkey_i *bch2_journal_iter_peek(struct journal_iter *iter)
k->btree_id == iter->btree_id &&
k->level == iter->level) {
if (!k->overwritten)
return k->k;
return bkey_i_to_s_c(k->k);
bch2_journal_iter_advance(iter);
k = iter->keys->d + iter->idx;
}
return NULL;
return bkey_s_c_null;
}
static void bch2_journal_iter_exit(struct journal_iter *iter)
@ -358,71 +354,49 @@ static void bch2_journal_iter_advance_btree(struct btree_and_journal_iter *iter)
void bch2_btree_and_journal_iter_advance(struct btree_and_journal_iter *iter)
{
switch (iter->last) {
case none:
break;
case btree:
bch2_journal_iter_advance_btree(iter);
break;
case journal:
bch2_journal_iter_advance(&iter->journal);
break;
}
iter->last = none;
if (!bpos_cmp(iter->pos, SPOS_MAX))
iter->at_end = true;
else
iter->pos = bpos_successor(iter->pos);
}
struct bkey_s_c bch2_btree_and_journal_iter_peek(struct btree_and_journal_iter *iter)
{
struct bkey_s_c ret;
struct bkey_s_c btree_k, journal_k, ret;
again:
if (iter->at_end)
return bkey_s_c_null;
while (1) {
struct bkey_s_c btree_k =
bch2_journal_iter_peek_btree(iter);
struct bkey_s_c journal_k =
bkey_i_to_s_c(bch2_journal_iter_peek(&iter->journal));
while ((btree_k = bch2_journal_iter_peek_btree(iter)).k &&
bpos_cmp(btree_k.k->p, iter->pos) < 0)
bch2_journal_iter_advance_btree(iter);
if (btree_k.k && journal_k.k) {
int cmp = bpos_cmp(btree_k.k->p, journal_k.k->p);
while ((journal_k = bch2_journal_iter_peek(&iter->journal)).k &&
bpos_cmp(journal_k.k->p, iter->pos) < 0)
bch2_journal_iter_advance(&iter->journal);
if (!cmp)
bch2_journal_iter_advance_btree(iter);
ret = journal_k.k &&
(!btree_k.k || bpos_cmp(journal_k.k->p, btree_k.k->p) <= 0)
? journal_k
: btree_k;
iter->last = cmp < 0 ? btree : journal;
} else if (btree_k.k) {
iter->last = btree;
} else if (journal_k.k) {
iter->last = journal;
} else {
iter->last = none;
return bkey_s_c_null;
if (ret.k && iter->b && bpos_cmp(ret.k->p, iter->b->data->max_key) > 0)
ret = bkey_s_c_null;
if (ret.k) {
iter->pos = ret.k->p;
if (bkey_deleted(ret.k)) {
bch2_btree_and_journal_iter_advance(iter);
goto again;
}
ret = iter->last == journal ? journal_k : btree_k;
if (iter->b &&
bpos_cmp(ret.k->p, iter->b->data->max_key) > 0) {
iter->journal.idx = iter->journal.keys->nr;
iter->last = none;
return bkey_s_c_null;
}
if (!bkey_deleted(ret.k))
break;
bch2_btree_and_journal_iter_advance(iter);
} else {
iter->pos = SPOS_MAX;
iter->at_end = true;
}
return ret;
}
struct bkey_s_c bch2_btree_and_journal_iter_next(struct btree_and_journal_iter *iter)
{
bch2_btree_and_journal_iter_advance(iter);
return bch2_btree_and_journal_iter_peek(iter);
}
void bch2_btree_and_journal_iter_exit(struct btree_and_journal_iter *iter)
{
bch2_journal_iter_exit(&iter->journal);
@ -440,6 +414,8 @@ void __bch2_btree_and_journal_iter_init_node_iter(struct btree_and_journal_iter
iter->node_iter = node_iter;
bch2_journal_iter_init(c, &iter->journal, b->c.btree_id, b->c.level, pos);
INIT_LIST_HEAD(&iter->journal.list);
iter->pos = b->data->min_key;
iter->at_end = false;
}
/*

9
fs/bcachefs/recovery.h
View File

@ -20,12 +20,8 @@ struct btree_and_journal_iter {
struct bkey unpacked;
struct journal_iter journal;
enum last_key_returned {
none,
btree,
journal,
} last;
struct bpos pos;
bool at_end;
};
struct bkey_i *bch2_journal_keys_peek_upto(struct bch_fs *, enum btree_id,
@ -44,7 +40,6 @@ void bch2_journal_key_overwritten(struct bch_fs *, enum btree_id,
void bch2_btree_and_journal_iter_advance(struct btree_and_journal_iter *);
struct bkey_s_c bch2_btree_and_journal_iter_peek(struct btree_and_journal_iter *);
struct bkey_s_c bch2_btree_and_journal_iter_next(struct btree_and_journal_iter *);
void bch2_btree_and_journal_iter_exit(struct btree_and_journal_iter *);
void __bch2_btree_and_journal_iter_init_node_iter(struct btree_and_journal_iter *,