libceph: kill last of ceph_msg_pos
The only remaining field in the ceph_msg_pos structure is
did_page_crc. In the new cursor model of things that flag (or
something like it) belongs in the cursor.
Define a new field "need_crc" in the cursor (which applies to all
types of data) and initialize it to true whenever a cursor is
initialized.
In write_partial_message_data(), the data CRC still will be computed
as before, but it will check the cursor->need_crc field to determine
whether it's needed. Any time the cursor is advanced to a new piece
of a data item, need_crc will be set, and this will cause the crc
for that entire piece to be accumulated into the data crc.
In write_partial_message_data() the intermediate crc value is now
held in a local variable so it doesn't have to be byte-swapped so
many times. In read_partial_msg_data() we do something similar
(but mainly for consistency there).
With that, the ceph_msg_pos structure can go away, and it no longer
needs to be passed as an argument to prepare_message_data().
This cleanup is related to:
http://tracker.ceph.com/issues/4428
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
index c76b228..686df5b 100644
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -93,6 +93,7 @@
struct ceph_msg_data_cursor {
size_t resid; /* bytes not yet consumed */
bool last_piece; /* now at last piece of data item */
+ bool need_crc; /* new piece; crc update needed */
union {
#ifdef CONFIG_BLOCK
struct { /* bio */
@@ -156,10 +157,6 @@
struct ceph_msgpool *pool;
};
-struct ceph_msg_pos {
- bool did_page_crc; /* true if we've calculated crc for current page */
-};
-
/* ceph connection fault delay defaults, for exponential backoff */
#define BASE_DELAY_INTERVAL (HZ/2)
#define MAX_DELAY_INTERVAL (5 * 60 * HZ)
@@ -217,7 +214,6 @@
struct ceph_msg *out_msg; /* sending message (== tail of
out_sent) */
bool out_msg_done;
- struct ceph_msg_pos out_msg_pos;
struct kvec out_kvec[8], /* sending header/footer data */
*out_kvec_cur;
@@ -231,7 +227,6 @@
/* message in temps */
struct ceph_msg_header in_hdr;
struct ceph_msg *in_msg;
- struct ceph_msg_pos in_msg_pos;
u32 in_front_crc, in_middle_crc, in_data_crc; /* calculated crc */
char in_tag; /* protocol control byte */