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bcachefs: Handle cached data LRU wraparound

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We only have 48 bits for the LRU time field, which is insufficient to
prevent wraparound.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2024-06-17 13:15:16 -04:00
parent cff07e2739
commit 2e9940d4a1
1 changed files with 41 additions and 5 deletions
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46
fs/bcachefs/alloc_background.c
View file

@ -2019,6 +2019,21 @@ static int invalidate_one_bucket(struct btree_trans *trans,
goto out;
}
static struct bkey_s_c next_lru_key(struct btree_trans *trans, struct btree_iter *iter,
struct bch_dev *ca, bool *wrapped)
{
struct bkey_s_c k;
again:
k = bch2_btree_iter_peek_upto(iter, lru_pos(ca->dev_idx, U64_MAX, LRU_TIME_MAX));
if (!k.k && !*wrapped) {
bch2_btree_iter_set_pos(iter, lru_pos(ca->dev_idx, 0, 0));
*wrapped = true;
goto again;
}
return k;
}
static void bch2_do_invalidates_work(struct work_struct *work)
{
struct bch_fs *c = container_of(work, struct bch_fs, invalidate_work);
@ -2032,12 +2047,33 @@ static void bch2_do_invalidates_work(struct work_struct *work)
for_each_member_device(c, ca) {
s64 nr_to_invalidate =
should_invalidate_buckets(ca, bch2_dev_usage_read(ca));
struct btree_iter iter;
bool wrapped = false;
ret = for_each_btree_key_upto(trans, iter, BTREE_ID_lru,
lru_pos(ca->dev_idx, 0, 0),
lru_pos(ca->dev_idx, U64_MAX, LRU_TIME_MAX),
BTREE_ITER_intent, k,
invalidate_one_bucket(trans, &iter, k, &nr_to_invalidate));
bch2_trans_iter_init(trans, &iter, BTREE_ID_lru,
lru_pos(ca->dev_idx, 0,
((bch2_current_io_time(c, READ) + U32_MAX) &
LRU_TIME_MAX)), 0);
while (true) {
bch2_trans_begin(trans);
struct bkey_s_c k = next_lru_key(trans, &iter, ca, &wrapped);
ret = bkey_err(k);
if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
continue;
if (ret)
break;
if (!k.k)
break;
ret = invalidate_one_bucket(trans, &iter, k, &nr_to_invalidate);
if (ret)
break;
bch2_btree_iter_advance(&iter);
}
bch2_trans_iter_exit(trans, &iter);
if (ret < 0) {
bch2_dev_put(ca);