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authorAlex Elder <elder@dreamhost.com>2012-02-15 07:43:54 -0600
committerAlex Elder <elder@dreamhost.com>2012-03-22 10:47:51 -0500
commita9a0c51af4e7c825c014b40694571456a75ebbc4 (patch)
tree6df7b2873d21f3c9c5e449aca1d8c16f4dd5fc1d /net/ceph
parentbca064d236a2e3162a07c758855221bcbe3c475b (diff)
downloadlinux-a9a0c51af4e7c825c014b40694571456a75ebbc4.tar.bz2
libceph: separate CRC calculation from byte swapping
Calculate CRC in a separate step from rearranging the byte order of the result, to improve clarity and readability. Use offsetof() to determine the number of bytes to include in the CRC calculation. In read_partial_message(), switch which value gets byte-swapped, since the just-computed CRC is already likely to be in a register. Signed-off-by: Alex Elder <elder@dreamhost.com> Signed-off-by: Sage Weil <sage@newdream.net>
Diffstat (limited to 'net/ceph')
-rw-r--r--net/ceph/messenger.c31
1 files changed, 17 insertions, 14 deletions
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 204e229e6628..7ec6a228b667 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -521,6 +521,7 @@ static void prepare_write_message_footer(struct ceph_connection *con)
static void prepare_write_message(struct ceph_connection *con)
{
struct ceph_msg *m;
+ u32 crc;
ceph_con_out_kvec_reset(con);
con->out_kvec_is_msg = true;
@@ -569,17 +570,17 @@ static void prepare_write_message(struct ceph_connection *con)
m->middle->vec.iov_base);
/* fill in crc (except data pages), footer */
- con->out_msg->hdr.crc =
- cpu_to_le32(crc32c(0, &m->hdr,
- sizeof(m->hdr) - sizeof(m->hdr.crc)));
+ crc = crc32c(0, &m->hdr, offsetof(struct ceph_msg_header, crc));
+ con->out_msg->hdr.crc = cpu_to_le32(crc);
con->out_msg->footer.flags = CEPH_MSG_FOOTER_COMPLETE;
- con->out_msg->footer.front_crc =
- cpu_to_le32(crc32c(0, m->front.iov_base, m->front.iov_len));
- if (m->middle)
- con->out_msg->footer.middle_crc =
- cpu_to_le32(crc32c(0, m->middle->vec.iov_base,
- m->middle->vec.iov_len));
- else
+
+ crc = crc32c(0, m->front.iov_base, m->front.iov_len);
+ con->out_msg->footer.front_crc = cpu_to_le32(crc);
+ if (m->middle) {
+ crc = crc32c(0, m->middle->vec.iov_base,
+ m->middle->vec.iov_len);
+ con->out_msg->footer.middle_crc = cpu_to_le32(crc);
+ } else
con->out_msg->footer.middle_crc = 0;
con->out_msg->footer.data_crc = 0;
dout("prepare_write_message front_crc %u data_crc %u\n",
@@ -875,12 +876,13 @@ static int write_partial_msg_pages(struct ceph_connection *con)
total_max_write);
if (do_crc && !con->out_msg_pos.did_page_crc) {
+ 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);
- con->out_msg->footer.data_crc =
- cpu_to_le32(crc32c(tmpcrc, base, len));
+ crc = crc32c(tmpcrc, base, len);
+ con->out_msg->footer.data_crc = cpu_to_le32(crc);
con->out_msg_pos.did_page_crc = true;
}
ret = kernel_sendpage(con->sock, page,
@@ -1650,8 +1652,9 @@ static int read_partial_message(struct ceph_connection *con)
con->in_base_pos += ret;
if (con->in_base_pos == sizeof(con->in_hdr)) {
u32 crc = crc32c(0, &con->in_hdr,
- sizeof(con->in_hdr) - sizeof(con->in_hdr.crc));
- if (crc != le32_to_cpu(con->in_hdr.crc)) {
+ offsetof(struct ceph_msg_header, crc));
+
+ if (cpu_to_le32(crc) != con->in_hdr.crc) {
pr_err("read_partial_message bad hdr "
" crc %u != expected %u\n",
crc, con->in_hdr.crc);