libceph: use cursor for inbound data pages

The cursor code for a page array selects the right page, page
offset, and length to use for a ceph_tcp_recvpage() call, so
we can use it to replace a block in read_partial_message_pages().

This partially resolves:
    http://tracker.ceph.com/issues/4428

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 b634d2098777656fef8156b3e5270e0126134c39..f81fbce136f837fb0e13540823c8da3528bd6e47 100644 (file)
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -1441,8 +1441,10 @@ static void in_msg_pos_next(struct ceph_connection *con, size_t len,
 
        msg_pos->data_pos += received;
        msg_pos->page_pos += received;
+       if (ceph_msg_has_pages(msg))
+               (void) ceph_msg_data_advance(&msg->p, received);
 #ifdef CONFIG_BLOCK
-       if (ceph_msg_has_bio(msg))
+       else if (ceph_msg_has_bio(msg))
                (void) ceph_msg_data_advance(&msg->b, received);
 #endif /* CONFIG_BLOCK */
        if (received < len)
@@ -2192,23 +2194,12 @@ static int read_partial_message_pages(struct ceph_connection *con,
                                      unsigned int data_len, bool do_datacrc)
 {
        struct ceph_msg *msg = con->in_msg;
-       struct ceph_msg_pos *msg_pos = &con->in_msg_pos;
-       struct page **pages;
        struct page *page;
        size_t page_offset;
        size_t length;
-       unsigned int left;
        int ret;
 
-       /* (page) data */
-       pages = msg->p.pages;
-       BUG_ON(pages == NULL);
-       page = pages[msg_pos->page];
-       page_offset = msg_pos->page_pos;
-       BUG_ON(msg_pos->data_pos >= data_len);
-       left = data_len - msg_pos->data_pos;
-       BUG_ON(page_offset >= PAGE_SIZE);
-       length = min_t(unsigned int, PAGE_SIZE - page_offset, left);
+       page = ceph_msg_data_next(&msg->p, &page_offset, &length, NULL);
 
        ret = ceph_tcp_recvpage(con->sock, page, page_offset, length);
        if (ret <= 0)