bcachefs: Don't touch journal_buf->data->seq in journal_res_get

This is a small optimization, reducing the number of cachelines we touch
in the fast path - and it's also necessary for the next patch that
increases JOURNAL_BUF_NR.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/journal.h b/fs/bcachefs/journal.h
index 1e5fcfe3624af1cce678bbe788be0629157e4a6f..e514d664b8aee6dc37f03fe3cf6bf52a69db631c 100644 (file)
--- a/fs/bcachefs/journal.h
+++ b/fs/bcachefs/journal.h
@@ -364,7 +364,10 @@ static inline int journal_res_get_fast(struct journal *j,
 
        res->ref        = true;
        res->offset     = old.cur_entry_offset;
-       res->seq        = le64_to_cpu(j->buf[old.idx].data->seq);
+       res->seq        = journal_cur_seq(j);
+       res->seq -= (res->seq - old.idx) & JOURNAL_BUF_MASK;
+
+       EBUG_ON(res->seq != le64_to_cpu(j->buf[old.idx].data->seq));
        return 1;
 }