libceph: define and use ceph_crc32c_page()

Factor out a common block of code that updates a CRC calculation
over a range of data in a page.

This and the preceding 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>

1 files changed, 20 insertions, 27 deletions

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 3120a6c81a76..f70bc92348d9 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -1085,6 +1085,19 @@ static void in_msg_pos_next(struct ceph_connection *con, size_t len,
 #endif /* CONFIG_BLOCK */
 }
 
+static u32 ceph_crc32c_page(u32 crc, struct page *page,
+                                unsigned int page_offset,
+                                unsigned int length)
+{
+        char *kaddr;
+
+        kaddr = kmap(page);
+        BUG_ON(kaddr == NULL);
+        crc = crc32c(crc, kaddr + page_offset, length);
+        kunmap(page);
+
+        return crc;
+}
 /*
  * Write as much message data payload as we can.  If we finish, queue
  * up the footer.
@@ -1153,15 +1166,9 @@ static int write_partial_message_data(struct ceph_connection *con)
 
                 page_offset = msg_pos->page_pos + bio_offset;
                 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 + page_offset;
-                        crc = crc32c(crc, base, length);
-                        kunmap(page);
+                        crc = ceph_crc32c_page(crc, page, page_offset, length);
                         msg->footer.data_crc = cpu_to_le32(crc);
                         msg_pos->did_page_crc = true;
                 }
@@ -1843,16 +1850,9 @@ static int read_partial_message_pages(struct ceph_connection *con,
         if (ret <= 0)
                 return 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);
-        }
+        if (do_datacrc)
+                con->in_data_crc = ceph_crc32c_page(con->in_data_crc, page,
+                                                        page_offset, ret);
 
         in_msg_pos_next(con, length, ret);
 
@@ -1886,16 +1886,9 @@ static int read_partial_message_bio(struct ceph_connection *con,
         if (ret <= 0)
                 return 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);
-        }
+        if (do_datacrc)
+                con->in_data_crc = ceph_crc32c_page(con->in_data_crc, page,
+                                                        page_offset, ret);
 
         in_msg_pos_next(con, length, ret);