libceph: advance pagelist with list_rotate_left()
While processing an outgoing pagelist (either the data pagelist or
trail) in a ceph message, the messenger cycles through each of the
pages on the list. This is accomplished in out_msg_pos_next(), if
the end of the first page on the list is reached, the first page is
moved to the end of the list.
There is a list operation, list_rotate_left(), which performs
exactly this operation, and by using it, what's really going on
becomes more obvious.
So replace these two list_move_tail() calls with list_rotate_left().
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index fb5f6e7..2734d03 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -1041,11 +1041,9 @@
con->out_msg_pos.page++;
con->out_msg_pos.did_page_crc = false;
if (in_trail)
- list_move_tail(&page->lru,
- &msg->trail->head);
+ list_rotate_left(&msg->trail->head);
else if (msg->pagelist)
- list_move_tail(&page->lru,
- &msg->pagelist->head);
+ list_rotate_left(&msg->pagelist->head);
#ifdef CONFIG_BLOCK
else if (msg->bio)
iter_bio_next(&msg->bio_iter, &msg->bio_seg);