[PATCH 3/5] bcachefs: Don't touch journal_buf->data->seq in journal_res_get

[Kent Overstreet <kent.overstreet@linux.dev>]

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>
---
 fs/bcachefs/journal.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/bcachefs/journal.h b/fs/bcachefs/journal.h
index 1e5fcfe3624a..e514d664b8ae 100644
--- 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;
 }
 
-- 
2.45.2