libceph: rename "page_shift" variable to something sensible
Alex Elder [Wed, 7 Mar 2012 17:40:08 +0000 (11:40 -0600)]
In write_partial_msg_pages() there is a local variable used to
track the starting offset within a bio segment to use.  Its name,
"page_shift" defies the Linux convention of using that name for
log-base-2(page size).

Since it's only used in the bio case rename it "bio_offset".  Use it
along with the page_pos field to compute the memory offset when
computing CRC's in that function.  This makes the bio case match the
others more closely.

Signed-off-by: Alex Elder <elder@dreamhost.com>
Reviewed-by: Sage Weil <sage@newdream.net>

net/ceph/messenger.c

index 4f1714c..2bf9ab4 100644 (file)
@@ -837,7 +837,7 @@ static int write_partial_msg_pages(struct ceph_connection *con)
                struct page *page = NULL;
                void *kaddr = NULL;
                int max_write = PAGE_SIZE;
-               int page_shift = 0;
+               int bio_offset = 0;
 
                total_max_write = data_len - trail_len -
                        con->out_msg_pos.data_pos;
@@ -874,9 +874,9 @@ static int write_partial_msg_pages(struct ceph_connection *con)
 
                        bv = bio_iovec_idx(msg->bio_iter, msg->bio_seg);
                        page = bv->bv_page;
-                       page_shift = bv->bv_offset;
+                       bio_offset = bv->bv_offset;
                        if (do_datacrc)
-                               kaddr = kmap(page) + page_shift;
+                               kaddr = kmap(page);
                        max_write = bv->bv_len;
 #endif
                } else {
@@ -888,17 +888,18 @@ static int write_partial_msg_pages(struct ceph_connection *con)
                            total_max_write);
 
                if (do_datacrc && !con->out_msg_pos.did_page_crc) {
+                       void *base;
                        u32 crc;
-                       void *base = kaddr + con->out_msg_pos.page_pos;
                        u32 tmpcrc = le32_to_cpu(con->out_msg->footer.data_crc);
 
                        BUG_ON(kaddr == NULL);
+                       base = kaddr + con->out_msg_pos.page_pos + bio_offset;
                        crc = crc32c(tmpcrc, base, len);
                        con->out_msg->footer.data_crc = cpu_to_le32(crc);
                        con->out_msg_pos.did_page_crc = true;
                }
                ret = ceph_tcp_sendpage(con->sock, page,
-                                     con->out_msg_pos.page_pos + page_shift,
+                                     con->out_msg_pos.page_pos + bio_offset,
                                      len, 1);
 
                if (do_datacrc)