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bcachefs: btree_iter_peek_with_updates()

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Introduce a new iterator method that provides a consistent view of the
btree plus uncommitted updates.

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 2020-03-05 18:44:59 -05:00 committed by Kent Overstreet
parent 7d6f9b6409
commit 57b0b3db47
2 changed files with 87 additions and 3 deletions
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83
fs/bcachefs/btree_iter.c
View File

@ -5,6 +5,7 @@
#include "btree_cache.h"
#include "btree_iter.h"
#include "btree_locking.h"
#include "btree_update.h"
#include "debug.h"
#include "extents.h"
#include "trace.h"
@ -1497,6 +1498,88 @@ struct bkey_s_c bch2_btree_iter_next(struct btree_iter *iter)
return bch2_btree_iter_peek(iter);
}
static struct bkey_s_c __btree_trans_updates_peek(struct btree_iter *iter)
{
struct bpos pos = btree_iter_search_key(iter);
struct btree_trans *trans = iter->trans;
struct btree_insert_entry *i;
trans_for_each_update(trans, i)
if ((cmp_int(iter->btree_id, i->iter->btree_id) ?:
bkey_cmp(pos, i->k->k.p)) <= 0)
break;
return i < trans->updates + trans->nr_updates &&
iter->btree_id == i->iter->btree_id
? bkey_i_to_s_c(i->k)
: bkey_s_c_null;
}
static struct bkey_s_c __bch2_btree_iter_peek_with_updates(struct btree_iter *iter)
{
struct btree_iter_level *l = &iter->l[0];
struct bkey_s_c k = __btree_iter_peek(iter, l);
struct bkey_s_c u = __btree_trans_updates_peek(iter);
if (k.k && (!u.k || bkey_cmp(k.k->p, u.k->p) < 0))
return k;
if (u.k && bkey_cmp(u.k->p, l->b->key.k.p) <= 0) {
iter->k = *u.k;
return u;
}
return bkey_s_c_null;
}
struct bkey_s_c bch2_btree_iter_peek_with_updates(struct btree_iter *iter)
{
struct bkey_s_c k;
int ret;
bch2_btree_iter_checks(iter, BTREE_ITER_KEYS);
while (1) {
ret = bch2_btree_iter_traverse(iter);
if (unlikely(ret))
return bkey_s_c_err(ret);
k = __bch2_btree_iter_peek_with_updates(iter);
if (k.k && bkey_deleted(k.k)) {
bch2_btree_iter_set_pos(iter,
btree_type_successor(iter->btree_id, iter->k.p));
continue;
}
if (likely(k.k))
break;
if (!btree_iter_set_pos_to_next_leaf(iter))
return bkey_s_c_null;
}
/*
* iter->pos should always be equal to the key we just
* returned - except extents can straddle iter->pos:
*/
if (!(iter->flags & BTREE_ITER_IS_EXTENTS) ||
bkey_cmp(bkey_start_pos(k.k), iter->pos) > 0)
iter->pos = bkey_start_pos(k.k);
iter->uptodate = BTREE_ITER_UPTODATE;
return k;
}
struct bkey_s_c bch2_btree_iter_next_with_updates(struct btree_iter *iter)
{
if (unlikely(!bkey_cmp(iter->k.p, POS_MAX)))
return bkey_s_c_null;
bch2_btree_iter_set_pos(iter,
btree_type_successor(iter->btree_id, iter->k.p));
return bch2_btree_iter_peek_with_updates(iter);
}
/**
* bch2_btree_iter_peek_prev: returns first key less than or equal to
* iterator's current position

7
fs/bcachefs/btree_iter.h
View File

@ -159,6 +159,9 @@ struct btree *bch2_btree_iter_next_node(struct btree_iter *);
struct bkey_s_c bch2_btree_iter_peek(struct btree_iter *);
struct bkey_s_c bch2_btree_iter_next(struct btree_iter *);
struct bkey_s_c bch2_btree_iter_peek_with_updates(struct btree_iter *);
struct bkey_s_c bch2_btree_iter_next_with_updates(struct btree_iter *);
struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_iter *);
struct bkey_s_c bch2_btree_iter_prev(struct btree_iter *);
@ -199,9 +202,7 @@ static inline int __btree_iter_cmp(enum btree_id id,
struct bpos pos,
const struct btree_iter *r)
{
if (id != r->btree_id)
return id < r->btree_id ? -1 : 1;
return bkey_cmp(pos, r->pos);
return cmp_int(id, r->btree_id) ?: bkey_cmp(pos, r->pos);
}
static inline int btree_iter_cmp(const struct btree_iter *l,