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bcachefs: Ensure iter->real_pos is consistent with key returned

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iter->real_pos needs to match the key returned or bad things will happen
when we go to update the key at that position. When we returned a
pending update from btree_trans_peek_updates(), this wasn't necessarily
the case.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2021-08-24 16:54:36 -04:00 committed by Kent Overstreet
parent 1865ccff15
commit e6e024e9bf
1 changed files with 42 additions and 40 deletions
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82
fs/bcachefs/btree_iter.c
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@ -1728,6 +1728,7 @@ static inline struct bkey_i *btree_trans_peek_updates(struct btree_iter *iter)
*/
struct bkey_s_c bch2_btree_iter_peek(struct btree_iter *iter)
{
struct btree_iter_level *l = &iter->l[0];
struct bpos search_key = btree_iter_search_key(iter);
struct bkey_i *next_update;
struct bkey_s_c k;
@ -1741,39 +1742,47 @@ struct bkey_s_c bch2_btree_iter_peek(struct btree_iter *iter)
btree_iter_set_search_pos(iter, search_key);
ret = btree_iter_traverse(iter);
if (unlikely(ret))
return bkey_s_c_err(ret);
if (unlikely(ret)) {
/* ensure that iter->k is consistent with iter->pos: */
bch2_btree_iter_set_pos(iter, iter->pos);
k = bkey_s_c_err(ret);
goto out;
}
/*
* btree_iter_level_peek() mutates iter->real_pos, which
* btree_trans_peek_updates() checks against, so we have to call
* them in this order:
*/
next_update = btree_trans_peek_updates(iter);
k = btree_iter_level_peek(iter, &iter->l[0]);
k = btree_iter_level_peek_all(iter, l);
/* * In the btree, deleted keys sort before non deleted: */
if (k.k && bkey_deleted(k.k) &&
(!next_update ||
bpos_cmp(k.k->p, next_update->k.p) <= 0)) {
search_key = k.k->p;
continue;
}
if (next_update &&
bpos_cmp(next_update->k.p, iter->real_pos) <= 0) {
bpos_cmp(next_update->k.p,
k.k ? k.k->p : l->b->key.k.p) <= 0) {
iter->k = next_update->k;
k = bkey_i_to_s_c(next_update);
}
if (likely(k.k)) {
if (bkey_deleted(k.k)) {
search_key = bkey_successor(iter, k.k->p);
continue;
}
if (likely(!bkey_deleted(k.k)))
break;
break;
}
if (unlikely(!bpos_cmp(iter->l[0].b->key.k.p, SPOS_MAX))) {
/* Advance to next key: */
search_key = bkey_successor(iter, k.k->p);
} else if (likely(bpos_cmp(l->b->key.k.p, SPOS_MAX))) {
/* Advance to next leaf node: */
search_key = bpos_successor(l->b->key.k.p);
} else {
/* End of btree: */
bch2_btree_iter_set_pos(iter, SPOS_MAX);
iter->real_pos = SPOS_MAX;
k = bkey_s_c_null;
goto out;
}
/* Advance to next leaf node: */
search_key = bpos_successor(iter->l[0].b->key.k.p);
}
/*
@ -1784,11 +1793,11 @@ struct bkey_s_c bch2_btree_iter_peek(struct btree_iter *iter)
iter->pos = k.k->p;
else if (bkey_cmp(bkey_start_pos(k.k), iter->pos) > 0)
iter->pos = bkey_start_pos(k.k);
iter->real_pos = k.k->p;
out:
iter->should_be_locked = true;
bch2_btree_iter_verify_entry_exit(iter);
bch2_btree_iter_verify(iter);
iter->should_be_locked = true;
return k;
}
@ -1825,8 +1834,10 @@ struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_iter *iter)
ret = btree_iter_traverse(iter);
if (unlikely(ret)) {
/* ensure that iter->k is consistent with iter->pos: */
bch2_btree_iter_set_pos(iter, iter->pos);
k = bkey_s_c_err(ret);
goto no_key;
goto out;
}
k = btree_iter_level_peek(iter, l);
@ -1836,17 +1847,17 @@ struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_iter *iter)
: bkey_cmp(k.k->p, iter->pos) > 0))
k = btree_iter_level_prev(iter, l);
if (likely(k.k))
if (likely(k.k)) {
break;
if (unlikely(!bpos_cmp(iter->l[0].b->data->min_key, POS_MIN))) {
} else if (likely(bpos_cmp(l->b->data->min_key, POS_MIN))) {
/* Advance to previous leaf node: */
search_key = bpos_predecessor(l->b->data->min_key);
} else {
/* Start of btree: */
bch2_btree_iter_set_pos(iter, POS_MIN);
k = bkey_s_c_null;
goto no_key;
goto out;
}
/* Advance to previous leaf node: */
search_key = bpos_predecessor(iter->l[0].b->data->min_key);
}
EBUG_ON(bkey_cmp(bkey_start_pos(k.k), iter->pos) > 0);
@ -1855,19 +1866,10 @@ struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_iter *iter)
if (bkey_cmp(k.k->p, iter->pos) < 0)
iter->pos = k.k->p;
out:
iter->should_be_locked = true;
bch2_btree_iter_verify_entry_exit(iter);
bch2_btree_iter_verify(iter);
iter->should_be_locked = true;
return k;
no_key:
/*
* btree_iter_level_peek() may have set iter->k to a key we didn't want, and
* then we errored going to the previous leaf - make sure it's
* consistent with iter->pos:
*/
bkey_init(&iter->k);
iter->k.p = iter->pos;
goto out;
}
/**