libceph: more cleanup of write_partial_msg_pages()

Basically all cases in write_partial_msg_pages() use the cursor, and
as a result we can simplify that function quite a bit.

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 ff58d31827541e8dd18fe1f661c5d06eb98ae32e..997daccf973ac2c58881c23293d937c4410c6e19 100644 (file)
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -1476,7 +1476,6 @@ static int write_partial_message_data(struct ceph_connection *con)
        unsigned int data_len = le32_to_cpu(msg->hdr.data_len);
        bool do_datacrc = !con->msgr->nocrc;
        int ret;
-       int total_max_write;
 
        dout("%s %p msg %p page %d offset %d\n", __func__,
             con, msg, msg_pos->page, msg_pos->page_pos);
@@ -1490,36 +1489,30 @@ static int write_partial_message_data(struct ceph_connection *con)
         * been revoked, so use the zero page.
         */
        while (data_len > msg_pos->data_pos) {
-               struct page *page = NULL;
+               struct page *page;
                size_t page_offset;
                size_t length;
-               bool use_cursor = false;
-               bool last_piece = true; /* preserve existing behavior */
-
-               total_max_write = data_len - msg_pos->data_pos;
+               bool last_piece;
 
                if (ceph_msg_has_pages(msg)) {
-                       use_cursor = true;
                        page = ceph_msg_data_next(&msg->p, &page_offset,
                                                        &length, &last_piece);
                } else if (ceph_msg_has_pagelist(msg)) {
-                       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)) {
-                       use_cursor = true;
                        page = ceph_msg_data_next(&msg->b, &page_offset,
                                                        &length, &last_piece);
 #endif
                } else {
-                       page = zero_page;
-               }
-               if (!use_cursor) {
-                       length = min_t(int, PAGE_SIZE - msg_pos->page_pos,
-                                           total_max_write);
+                       size_t resid = data_len - msg_pos->data_pos;
 
+                       page = zero_page;
                        page_offset = msg_pos->page_pos;
+                       length = PAGE_SIZE - page_offset;
+                       length = min(resid, length);
+                       last_piece = length == resid;
                }
                if (do_datacrc && !msg_pos->did_page_crc) {
                        u32 crc = le32_to_cpu(msg->footer.data_crc);