Commit 7fe1e5e5 authored by Alex Elder's avatar Alex Elder Committed by Sage Weil
Browse files

libceph: use data cursor for message pagelist 



Switch to using the message cursor for the (non-trail) outgoing
pagelist data item in a message if present.

Notes on the logic changes in out_msg_pos_next():
    - only the mds client uses a ceph pagelist for message data;
    - if the mds client ever uses a pagelist, it never uses a page
      array (or anything else, for that matter) for data in the same
      message;
    - only the osd client uses the trail portion of a message data,
      and when it does, it never uses any other data fields for
      outgoing data in the same message; and finally
    - only the rbd client uses bio message data (never pagelist).

Therefore out_msg_pos_next() can assume:
    - if we're in the trail portion of a message, the message data
      pagelist, data, and bio can be ignored; and
    - if there is a page list, there will never be any a bio or page
      array data, and vice-versa.

Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent dd236fcb

net/ceph/messenger.c

+13 −12
Original line number Diff line number Diff line
@@ -931,8 +931,10 @@ static void prepare_message_data(struct ceph_msg *msg, 
#endif

	msg_pos->data_pos = 0;



	/* If there's a trail, initialize its cursor */

	/* Initialize data cursors */



	if (ceph_msg_has_pagelist(msg))

		ceph_msg_data_cursor_init(&msg->l);

	if (ceph_msg_has_trail(msg))

		ceph_msg_data_cursor_init(&msg->t);
@@ -1220,18 +1222,19 @@ static void out_msg_pos_next(struct ceph_connection *con, struct page *page, 
{

	struct ceph_msg *msg = con->out_msg;

	struct ceph_msg_pos *msg_pos = &con->out_msg_pos;

	bool need_crc = false;



	BUG_ON(!msg);

	BUG_ON(!sent);



	msg_pos->data_pos += sent;

	msg_pos->page_pos += sent;

	if (in_trail) {

		bool need_crc;



	if (in_trail)

		need_crc = ceph_msg_data_advance(&msg->t, sent);

	else if (ceph_msg_has_pagelist(msg))

		need_crc = ceph_msg_data_advance(&msg->l, sent);

	BUG_ON(need_crc && sent != len);

	}



	if (sent < len)

		return;
@@ -1239,14 +1242,11 @@ static void out_msg_pos_next(struct ceph_connection *con, struct page *page, 
	msg_pos->page_pos = 0;

	msg_pos->page++;

	msg_pos->did_page_crc = false;

	if (ceph_msg_has_pagelist(msg)) {

		list_rotate_left(&msg->l.pagelist->head);

#ifdef CONFIG_BLOCK

	} else if (ceph_msg_has_bio(msg)) {

	if (ceph_msg_has_bio(msg))

		iter_bio_next(&msg->b.bio_iter, &msg->b.bio_seg);

#endif

}

}



static void in_msg_pos_next(struct ceph_connection *con, size_t len,

				size_t received)
@@ -1340,8 +1340,9 @@ static int write_partial_message_data(struct ceph_connection *con) 
		} else if (ceph_msg_has_pages(msg)) {

			page = msg->p.pages[msg_pos->page];

		} else if (ceph_msg_has_pagelist(msg)) {

			page = list_first_entry(&msg->l.pagelist->head,

						struct page, lru);

			use_cursor = true;

			page = ceph_msg_data_next(&msg->l, &page_offset,

							&length, &last_piece);

#ifdef CONFIG_BLOCK

		} else if (ceph_msg_has_bio(msg)) {

			struct bio_vec *bv;

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