libceph: define and use ceph_tcp_recvpage()

Define a new function ceph_tcp_recvpage() that behaves in a way
comparable to ceph_tcp_sendpage().

Rearrange the code in both read_partial_message_pages() and
read_partial_message_bio() so they have matching structure,
(similar to what's in write_partial_msg_pages()), and use
this new function.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

1 files changed, 60 insertions, 26 deletions

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 6e0bd36d676a..3120a6c81a76 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -471,6 +471,22 @@ static int ceph_tcp_recvmsg(struct socket *sock, void *buf, size_t len)
         return r;
 }
 
+static int ceph_tcp_recvpage(struct socket *sock, struct page *page,
+                     int page_offset, size_t length)
+{
+        void *kaddr;
+        int ret;
+
+        BUG_ON(page_offset + length > PAGE_SIZE);
+
+        kaddr = kmap(page);
+        BUG_ON(!kaddr);
+        ret = ceph_tcp_recvmsg(sock, kaddr + page_offset, length);
+        kunmap(page);
+
+        return ret;
+}
+
 /*
  * write something.  @more is true if caller will be sending more data
  * shortly.
@@ -1809,26 +1825,36 @@ static int read_partial_message_pages(struct ceph_connection *con,
 {
         struct ceph_msg_pos *msg_pos = &con->in_msg_pos;
         struct page *page;
-        void *p;
+        size_t page_offset;
+        size_t length;
+        unsigned int left;
         int ret;
-        int left;
 
-        left = min((int)(data_len - msg_pos->data_pos),
-                   (int)(PAGE_SIZE - msg_pos->page_pos));
         /* (page) data */
         BUG_ON(pages == NULL);
         page = pages[msg_pos->page];
-        p = kmap(page);
-        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 + msg_pos->page_pos, ret);
-        kunmap(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);
+
+        ret = ceph_tcp_recvpage(con->sock, page, page_offset, length);
         if (ret <= 0)
                 return ret;
 
-        in_msg_pos_next(con, left, ret);
+        if (do_datacrc) {
+                void *kaddr;
+                void *base;
+
+                kaddr = kmap(page);
+                BUG_ON(!kaddr);
+                base = kaddr + page_offset;
+                con->in_data_crc = crc32c(con->in_data_crc, base, ret);
+                kunmap(page);
+        }
+
+        in_msg_pos_next(con, length, ret);
 
         return ret;
 }
@@ -1841,29 +1867,37 @@ static int read_partial_message_bio(struct ceph_connection *con,
         struct ceph_msg_pos *msg_pos = &con->in_msg_pos;
         struct bio_vec *bv;
         struct page *page;
-        void *p;
-        int ret, left;
+        size_t page_offset;
+        size_t length;
+        unsigned int left;
+        int ret;
 
         BUG_ON(!msg);
         BUG_ON(!msg->bio_iter);
         bv = bio_iovec_idx(msg->bio_iter, msg->bio_seg);
-
-        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;
+        page_offset = bv->bv_offset + msg_pos->page_pos;
+        BUG_ON(msg_pos->data_pos >= data_len);
+        left = data_len - msg_pos->data_pos;
+        BUG_ON(msg_pos->page_pos >= bv->bv_len);
+        length = min_t(unsigned int, bv->bv_len - 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 + msg_pos->page_pos, ret);
-        kunmap(page);
+        ret = ceph_tcp_recvpage(con->sock, page, page_offset, length);
         if (ret <= 0)
                 return ret;
 
-        in_msg_pos_next(con, left, ret);
+        if (do_datacrc) {
+                void *kaddr;
+                void *base;
+
+                kaddr = kmap(page);
+                BUG_ON(!kaddr);
+                base = kaddr + page_offset;
+                con->in_data_crc = crc32c(con->in_data_crc, base, ret);
+                kunmap(page);
+        }
+
+        in_msg_pos_next(con, length, ret);
 
         return ret;
 }