bcachefs: Add a pre-reserve mechanism for the journal
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet
Kent Overstreet
parent
9ace606e93
commit
68ef94a63c
@ -343,6 +343,16 @@ retry:
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return 0;
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}
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if (!(flags & JOURNAL_RES_GET_RESERVED) &&
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!test_bit(JOURNAL_MAY_GET_UNRESERVED, &j->flags)) {
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/*
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* Don't want to close current journal entry, just need to
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* invoke reclaim:
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*/
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ret = -ENOSPC;
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goto unlock;
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}
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/*
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* If we couldn't get a reservation because the current buf filled up,
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* and we had room for a bigger entry on disk, signal that we want to
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@ -366,7 +376,7 @@ retry:
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} else {
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ret = journal_entry_open(j);
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}
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unlock:
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if ((ret == -EAGAIN || ret == -ENOSPC) &&
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!j->res_get_blocked_start)
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j->res_get_blocked_start = local_clock() ?: 1;
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@ -378,6 +388,8 @@ retry:
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goto retry;
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if (ret == -ENOSPC) {
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BUG_ON(!can_discard && (flags & JOURNAL_RES_GET_RESERVED));
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/*
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* Journal is full - can't rely on reclaim from work item due to
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* freezing:
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@ -423,6 +435,32 @@ int bch2_journal_res_get_slowpath(struct journal *j, struct journal_res *res,
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return ret;
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}
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/* journal_preres: */
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static bool journal_preres_available(struct journal *j,
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struct journal_preres *res,
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unsigned new_u64s)
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{
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bool ret = bch2_journal_preres_get_fast(j, res, new_u64s);
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if (!ret)
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bch2_journal_reclaim_work(&j->reclaim_work.work);
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return ret;
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}
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int __bch2_journal_preres_get(struct journal *j,
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struct journal_preres *res,
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unsigned new_u64s)
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{
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int ret;
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closure_wait_event(&j->preres_wait,
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(ret = bch2_journal_error(j)) ||
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journal_preres_available(j, res, new_u64s));
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return ret;
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}
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/* journal_entry_res: */
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void bch2_journal_entry_res_resize(struct journal *j,
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@ -1110,11 +1148,16 @@ ssize_t bch2_journal_print_debug(struct journal *j, char *buf)
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"seq:\t\t\t%llu\n"
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"last_seq:\t\t%llu\n"
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"last_seq_ondisk:\t%llu\n"
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"prereserved:\t\t%u/%u\n"
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"current entry sectors:\t%u\n"
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"current entry:\t\t",
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fifo_used(&j->pin),
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journal_cur_seq(j),
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journal_last_seq(j),
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j->last_seq_ondisk);
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j->last_seq_ondisk,
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j->prereserved.reserved,
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j->prereserved.remaining,
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j->cur_entry_sectors);
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switch (s.cur_entry_offset) {
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case JOURNAL_ENTRY_ERROR_VAL:
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@ -1136,8 +1179,9 @@ ssize_t bch2_journal_print_debug(struct journal *j, char *buf)
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journal_state_count(s, s.idx));
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if (s.prev_buf_unwritten)
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pr_buf(&out, "yes, ref %u\n",
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journal_state_count(s, !s.idx));
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pr_buf(&out, "yes, ref %u sectors %u\n",
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journal_state_count(s, !s.idx),
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journal_prev_buf(j)->sectors);
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else
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pr_buf(&out, "no\n");
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@ -119,6 +119,7 @@ static inline void journal_wake(struct journal *j)
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{
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wake_up(&j->wait);
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closure_wake_up(&j->async_wait);
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closure_wake_up(&j->preres_wait);
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}
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static inline struct journal_buf *journal_cur_buf(struct journal *j)
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@ -274,6 +275,7 @@ int bch2_journal_res_get_slowpath(struct journal *, struct journal_res *,
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#define JOURNAL_RES_GET_NONBLOCK (1 << 0)
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#define JOURNAL_RES_GET_CHECK (1 << 1)
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#define JOURNAL_RES_GET_RESERVED (1 << 2)
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static inline int journal_res_get_fast(struct journal *j,
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struct journal_res *res,
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@ -294,6 +296,10 @@ static inline int journal_res_get_fast(struct journal *j,
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EBUG_ON(!journal_state_count(new, new.idx));
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if (!(flags & JOURNAL_RES_GET_RESERVED) &&
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!test_bit(JOURNAL_MAY_GET_UNRESERVED, &j->flags))
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return 0;
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if (flags & JOURNAL_RES_GET_CHECK)
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return 1;
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@ -333,6 +339,89 @@ out:
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return 0;
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}
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/* journal_preres: */
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static inline bool journal_check_may_get_unreserved(struct journal *j)
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{
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union journal_preres_state s = READ_ONCE(j->prereserved);
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bool ret = s.reserved <= s.remaining &&
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fifo_free(&j->pin) > 8;
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lockdep_assert_held(&j->lock);
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if (ret != test_bit(JOURNAL_MAY_GET_UNRESERVED, &j->flags)) {
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if (ret) {
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set_bit(JOURNAL_MAY_GET_UNRESERVED, &j->flags);
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journal_wake(j);
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} else {
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clear_bit(JOURNAL_MAY_GET_UNRESERVED, &j->flags);
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}
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}
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return ret;
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}
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static inline void bch2_journal_preres_put(struct journal *j,
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struct journal_preres *res)
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{
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union journal_preres_state s = { .reserved = res->u64s };
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if (!res->u64s)
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return;
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s.v = atomic64_sub_return(s.v, &j->prereserved.counter);
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res->u64s = 0;
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closure_wake_up(&j->preres_wait);
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if (s.reserved <= s.remaining &&
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!test_bit(JOURNAL_MAY_GET_UNRESERVED, &j->flags)) {
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spin_lock(&j->lock);
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journal_check_may_get_unreserved(j);
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spin_unlock(&j->lock);
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}
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}
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int __bch2_journal_preres_get(struct journal *,
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struct journal_preres *, unsigned);
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static inline int bch2_journal_preres_get_fast(struct journal *j,
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struct journal_preres *res,
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unsigned new_u64s)
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{
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int d = new_u64s - res->u64s;
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union journal_preres_state old, new;
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u64 v = atomic64_read(&j->prereserved.counter);
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do {
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old.v = new.v = v;
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new.reserved += d;
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if (new.reserved > new.remaining)
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return 0;
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} while ((v = atomic64_cmpxchg(&j->prereserved.counter,
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old.v, new.v)) != old.v);
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res->u64s += d;
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return 1;
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}
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static inline int bch2_journal_preres_get(struct journal *j,
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struct journal_preres *res,
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unsigned new_u64s,
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unsigned flags)
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{
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if (new_u64s <= res->u64s)
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return 0;
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if (bch2_journal_preres_get_fast(j, res, new_u64s))
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return 0;
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if (flags & JOURNAL_RES_GET_NONBLOCK)
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return -EAGAIN;
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return __bch2_journal_preres_get(j, res, new_u64s);
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}
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/* journal_entry_res: */
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void bch2_journal_entry_res_resize(struct journal *,
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@ -974,6 +974,12 @@ static int journal_write_alloc(struct journal *j, struct journal_buf *w,
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journal_space_discarded)) {
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ja->cur_idx = (ja->cur_idx + 1) % ja->nr;
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ja->sectors_free = ca->mi.bucket_size;
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/*
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* ja->bucket_seq[ja->cur_idx] must always have
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* something sensible:
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*/
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ja->bucket_seq[ja->cur_idx] = le64_to_cpu(w->data->seq);
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}
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}
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@ -49,6 +49,18 @@ unsigned bch2_journal_dev_buckets_available(struct journal *j,
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return available;
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}
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static void journal_set_remaining(struct journal *j, unsigned u64s_remaining)
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{
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union journal_preres_state old, new;
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u64 v = atomic64_read(&j->prereserved.counter);
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do {
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old.v = new.v = v;
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new.remaining = u64s_remaining;
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} while ((v = atomic64_cmpxchg(&j->prereserved.counter,
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old.v, new.v)) != old.v);
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}
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static struct journal_space {
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unsigned next_entry;
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unsigned remaining;
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@ -124,8 +136,9 @@ void bch2_journal_space_available(struct journal *j)
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struct bch_fs *c = container_of(j, struct bch_fs, journal);
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struct bch_dev *ca;
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struct journal_space discarded, clean_ondisk, clean;
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unsigned max_entry_size = min(j->buf[0].buf_size >> 9,
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j->buf[1].buf_size >> 9);
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unsigned overhead, u64s_remaining = 0;
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unsigned max_entry_size = min(j->buf[0].buf_size >> 9,
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j->buf[1].buf_size >> 9);
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unsigned i, nr_online = 0, nr_devs_want;
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bool can_discard = false;
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int ret = 0;
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@ -176,9 +189,17 @@ void bch2_journal_space_available(struct journal *j)
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if (!discarded.next_entry)
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ret = -ENOSPC;
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overhead = DIV_ROUND_UP(clean.remaining, max_entry_size) *
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journal_entry_overhead(j);
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u64s_remaining = clean.remaining << 6;
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u64s_remaining = max_t(int, 0, u64s_remaining - overhead);
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u64s_remaining /= 4;
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out:
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j->cur_entry_sectors = !ret ? discarded.next_entry : 0;
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j->cur_entry_error = ret;
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journal_set_remaining(j, u64s_remaining);
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journal_check_may_get_unreserved(j);
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if (!ret)
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journal_wake(j);
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@ -454,7 +475,7 @@ void bch2_journal_reclaim(struct journal *j)
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{
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struct bch_fs *c = container_of(j, struct bch_fs, journal);
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struct bch_dev *ca;
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unsigned iter, bucket_to_flush, min_nr = 0;
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unsigned iter, min_nr = 0;
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u64 seq_to_flush = 0;
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lockdep_assert_held(&j->reclaim_lock);
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@ -465,13 +486,22 @@ void bch2_journal_reclaim(struct journal *j)
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for_each_rw_member(ca, c, iter) {
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struct journal_device *ja = &ca->journal;
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unsigned nr_buckets, bucket_to_flush;
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if (!ja->nr)
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continue;
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/* Try to keep the journal at most half full: */
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bucket_to_flush = (ja->cur_idx + (ja->nr >> 1)) % ja->nr;
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nr_buckets = ja->nr / 2;
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/* And include pre-reservations: */
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nr_buckets += DIV_ROUND_UP(j->prereserved.reserved,
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(ca->mi.bucket_size << 6) -
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journal_entry_overhead(j));
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nr_buckets = min(nr_buckets, ja->nr);
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bucket_to_flush = (ja->cur_idx + nr_buckets) % ja->nr;
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seq_to_flush = max_t(u64, seq_to_flush,
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ja->bucket_seq[bucket_to_flush]);
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}
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@ -490,6 +520,9 @@ void bch2_journal_reclaim(struct journal *j)
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msecs_to_jiffies(j->reclaim_delay_ms)))
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min_nr = 1;
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if (j->prereserved.reserved * 2 > j->prereserved.remaining)
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min_nr = 1;
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journal_flush_pins(j, seq_to_flush, min_nr);
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if (!test_bit(BCH_FS_RO, &c->flags))
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@ -80,6 +80,14 @@ struct journal_res {
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u64 seq;
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};
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/*
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* For reserving space in the journal prior to getting a reservation on a
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* particular journal entry:
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*/
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struct journal_preres {
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unsigned u64s;
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};
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union journal_res_state {
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struct {
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atomic64_t counter;
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@ -98,6 +106,21 @@ union journal_res_state {
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};
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};
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union journal_preres_state {
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struct {
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atomic64_t counter;
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};
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struct {
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u64 v;
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};
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struct {
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u32 reserved;
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u32 remaining;
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};
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};
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/* bytes: */
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#define JOURNAL_ENTRY_SIZE_MIN (64U << 10) /* 64k */
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#define JOURNAL_ENTRY_SIZE_MAX (4U << 20) /* 4M */
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@ -122,6 +145,7 @@ enum {
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JOURNAL_STARTED,
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JOURNAL_NEED_WRITE,
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JOURNAL_NOT_EMPTY,
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JOURNAL_MAY_GET_UNRESERVED,
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};
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/* Embedded in struct bch_fs */
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@ -142,6 +166,8 @@ struct journal {
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*/
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int cur_entry_error;
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union journal_preres_state prereserved;
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/* Reserved space in journal entry to be used just prior to write */
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unsigned entry_u64s_reserved;
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@ -161,6 +187,7 @@ struct journal {
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/* Used when waiting because the journal was full */
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wait_queue_head_t wait;
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struct closure_waitlist async_wait;
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struct closure_waitlist preres_wait;
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struct closure io;
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struct delayed_work write_work;
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