libceph: use local variables for message positions

There are several places where a message's out_msg_pos or in_msg_pos
field is used repeatedly within a function.  Use a local pointer
variable for this purpose to unclutter the code.

This and the upcoming cleanup patches are related to:
    http://tracker.ceph.com/issues/4403

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 17d9321b71343a9f50ab3cd43b74b190ba806bb4..7788170524e3c410741163cc08159c74f92d8dc9 100644 (file)
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -725,22 +725,23 @@ static void iter_bio_next(struct bio **bio_iter, unsigned int *seg)
 static void prepare_write_message_data(struct ceph_connection *con)
 {
        struct ceph_msg *msg = con->out_msg;
+       struct ceph_msg_pos *msg_pos = &con->out_msg_pos;
 
        BUG_ON(!msg);
        BUG_ON(!msg->hdr.data_len);
 
        /* initialize page iterator */
-       con->out_msg_pos.page = 0;
+       msg_pos->page = 0;
        if (msg->pages)
-               con->out_msg_pos.page_pos = msg->page_alignment;
+               msg_pos->page_pos = msg->page_alignment;
        else
-               con->out_msg_pos.page_pos = 0;
+               msg_pos->page_pos = 0;
 #ifdef CONFIG_BLOCK
        if (msg->bio)
                init_bio_iter(msg->bio, &msg->bio_iter, &msg->bio_seg);
 #endif
-       con->out_msg_pos.data_pos = 0;
-       con->out_msg_pos.did_page_crc = false;
+       msg_pos->data_pos = 0;
+       msg_pos->did_page_crc = false;
        con->out_more = 1;  /* data + footer will follow */
 }
 
@@ -1022,19 +1023,20 @@ static void out_msg_pos_next(struct ceph_connection *con, struct page *page,
                        size_t len, size_t sent, bool in_trail)
 {
        struct ceph_msg *msg = con->out_msg;
+       struct ceph_msg_pos *msg_pos = &con->out_msg_pos;
 
        BUG_ON(!msg);
        BUG_ON(!sent);
 
-       con->out_msg_pos.data_pos += sent;
-       con->out_msg_pos.page_pos += sent;
+       msg_pos->data_pos += sent;
+       msg_pos->page_pos += sent;
        if (sent < len)
                return;
 
        BUG_ON(sent != len);
-       con->out_msg_pos.page_pos = 0;
-       con->out_msg_pos.page++;
-       con->out_msg_pos.did_page_crc = false;
+       msg_pos->page_pos = 0;
+       msg_pos->page++;
+       msg_pos->did_page_crc = false;
        if (in_trail)
                list_rotate_left(&msg->trail->head);
        else if (msg->pagelist)
@@ -1049,18 +1051,19 @@ static void in_msg_pos_next(struct ceph_connection *con, size_t len,
                                size_t received)
 {
        struct ceph_msg *msg = con->in_msg;
+       struct ceph_msg_pos *msg_pos = &con->in_msg_pos;
 
        BUG_ON(!msg);
        BUG_ON(!received);
 
-       con->in_msg_pos.data_pos += received;
-       con->in_msg_pos.page_pos += received;
+       msg_pos->data_pos += received;
+       msg_pos->page_pos += received;
        if (received < len)
                return;
 
        BUG_ON(received != len);
-       con->in_msg_pos.page_pos = 0;
-       con->in_msg_pos.page++;
+       msg_pos->page_pos = 0;
+       msg_pos->page++;
 #ifdef CONFIG_BLOCK
        if (msg->bio)
                iter_bio_next(&msg->bio_iter, &msg->bio_seg);
@@ -1077,6 +1080,7 @@ static void in_msg_pos_next(struct ceph_connection *con, size_t len,
 static int write_partial_msg_pages(struct ceph_connection *con)
 {
        struct ceph_msg *msg = con->out_msg;
+       struct ceph_msg_pos *msg_pos = &con->out_msg_pos;
        unsigned int data_len = le32_to_cpu(msg->hdr.data_len);
        size_t len;
        bool do_datacrc = !con->msgr->nocrc;
@@ -1087,7 +1091,7 @@ static int write_partial_msg_pages(struct ceph_connection *con)
        const size_t trail_off = data_len - trail_len;
 
        dout("write_partial_msg_pages %p msg %p page %d offset %d\n",
-            con, msg, con->out_msg_pos.page, con->out_msg_pos.page_pos);
+            con, msg, msg_pos->page, msg_pos->page_pos);
 
        /*
         * Iterate through each page that contains data to be
@@ -1097,22 +1101,22 @@ static int write_partial_msg_pages(struct ceph_connection *con)
         * need to map the page.  If we have no pages, they have
         * been revoked, so use the zero page.
         */
-       while (data_len > con->out_msg_pos.data_pos) {
+       while (data_len > msg_pos->data_pos) {
                struct page *page = NULL;
                int max_write = PAGE_SIZE;
                int bio_offset = 0;
 
-               in_trail = in_trail || con->out_msg_pos.data_pos >= trail_off;
+               in_trail = in_trail || msg_pos->data_pos >= trail_off;
                if (!in_trail)
-                       total_max_write = trail_off - con->out_msg_pos.data_pos;
+                       total_max_write = trail_off - msg_pos->data_pos;
 
                if (in_trail) {
-                       total_max_write = data_len - con->out_msg_pos.data_pos;
+                       total_max_write = data_len - msg_pos->data_pos;
 
                        page = list_first_entry(&msg->trail->head,
                                                struct page, lru);
                } else if (msg->pages) {
-                       page = msg->pages[con->out_msg_pos.page];
+                       page = msg->pages[msg_pos->page];
                } else if (msg->pagelist) {
                        page = list_first_entry(&msg->pagelist->head,
                                                struct page, lru);
@@ -1128,24 +1132,24 @@ static int write_partial_msg_pages(struct ceph_connection *con)
                } else {
                        page = zero_page;
                }
-               len = min_t(int, max_write - con->out_msg_pos.page_pos,
+               len = min_t(int, max_write - msg_pos->page_pos,
                            total_max_write);
 
-               if (do_datacrc && !con->out_msg_pos.did_page_crc) {
+               if (do_datacrc && !msg_pos->did_page_crc) {
                        void *base;
                        u32 crc = le32_to_cpu(msg->footer.data_crc);
                        char *kaddr;
 
                        kaddr = kmap(page);
                        BUG_ON(kaddr == NULL);
-                       base = kaddr + con->out_msg_pos.page_pos + bio_offset;
+                       base = kaddr + msg_pos->page_pos + bio_offset;
                        crc = crc32c(crc, base, len);
                        kunmap(page);
                        msg->footer.data_crc = cpu_to_le32(crc);
-                       con->out_msg_pos.did_page_crc = true;
+                       msg_pos->did_page_crc = true;
                }
                ret = ceph_tcp_sendpage(con->sock, page,
-                                     con->out_msg_pos.page_pos + bio_offset,
+                                     msg_pos->page_pos + bio_offset,
                                      len, true);
                if (ret <= 0)
                        goto out;
@@ -1803,22 +1807,23 @@ static int read_partial_message_pages(struct ceph_connection *con,
                                      struct page **pages,
                                      unsigned int data_len, bool do_datacrc)
 {
+       struct ceph_msg_pos *msg_pos = &con->in_msg_pos;
        struct page *page;
        void *p;
        int ret;
        int left;
 
-       left = min((int)(data_len - con->in_msg_pos.data_pos),
-                  (int)(PAGE_SIZE - con->in_msg_pos.page_pos));
+       left = min((int)(data_len - msg_pos->data_pos),
+                  (int)(PAGE_SIZE - msg_pos->page_pos));
        /* (page) data */
        BUG_ON(pages == NULL);
-       page = pages[con->in_msg_pos.page];
+       page = pages[msg_pos->page];
        p = kmap(page);
-       ret = ceph_tcp_recvmsg(con->sock, p + con->in_msg_pos.page_pos, left);
+       ret = ceph_tcp_recvmsg(con->sock, p + msg_pos->page_pos, left);
        if (ret > 0 && do_datacrc)
                con->in_data_crc =
                        crc32c(con->in_data_crc,
-                                 p + con->in_msg_pos.page_pos, ret);
+                                 p + msg_pos->page_pos, ret);
        kunmap(page);
        if (ret <= 0)
                return ret;
@@ -1833,6 +1838,7 @@ static int read_partial_message_bio(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 bio_vec *bv;
        struct page *page;
        void *p;
@@ -1842,17 +1848,17 @@ static int read_partial_message_bio(struct ceph_connection *con,
        BUG_ON(!msg->bio_iter);
        bv = bio_iovec_idx(msg->bio_iter, msg->bio_seg);
 
-       left = min((int)(data_len - con->in_msg_pos.data_pos),
-                  (int)(bv->bv_len - con->in_msg_pos.page_pos));
+       left = min((int)(data_len - msg_pos->data_pos),
+                  (int)(bv->bv_len - msg_pos->page_pos));
 
        page = bv->bv_page;
        p = kmap(page) + bv->bv_offset;
 
-       ret = ceph_tcp_recvmsg(con->sock, p + con->in_msg_pos.page_pos, left);
+       ret = ceph_tcp_recvmsg(con->sock, p + msg_pos->page_pos, left);
        if (ret > 0 && do_datacrc)
                con->in_data_crc =
                        crc32c(con->in_data_crc,
-                                 p + con->in_msg_pos.page_pos, ret);
+                                 p + msg_pos->page_pos, ret);
        kunmap(page);
        if (ret <= 0)
                return ret;
@@ -1869,6 +1875,7 @@ static int read_partial_message_bio(struct ceph_connection *con,
 static int read_partial_message(struct ceph_connection *con)
 {
        struct ceph_msg *m = con->in_msg;
+       struct ceph_msg_pos *msg_pos = &con->in_msg_pos;
        int size;
        int end;
        int ret;
@@ -1949,12 +1956,12 @@ static int read_partial_message(struct ceph_connection *con)
                if (m->middle)
                        m->middle->vec.iov_len = 0;
 
-               con->in_msg_pos.page = 0;
+               msg_pos->page = 0;
                if (m->pages)
-                       con->in_msg_pos.page_pos = m->page_alignment;
+                       msg_pos->page_pos = m->page_alignment;
                else
-                       con->in_msg_pos.page_pos = 0;
-               con->in_msg_pos.data_pos = 0;
+                       msg_pos->page_pos = 0;
+               msg_pos->data_pos = 0;
 
 #ifdef CONFIG_BLOCK
                if (m->bio)
@@ -1978,7 +1985,7 @@ static int read_partial_message(struct ceph_connection *con)
        }
 
        /* (page) data */
-       while (con->in_msg_pos.data_pos < data_len) {
+       while (msg_pos->data_pos < data_len) {
                if (m->pages) {
                        ret = read_partial_message_pages(con, m->pages,
                                                 data_len, do_datacrc);