[PATCH 4/6, v2] libceph: encapsulate reading message data

[Alex Elder <elder@inktank.com>]

The previously posted edition of this patch erroneously moved the
initialization of the message position information so it happened
every time the message was read rather than just when the message
was first initialized.  This one no longer does that.

Pull the code that reads the data portion into a message into
a separate function read_partial_msg_data().

Rename write_partial_msg_pages() to be write_partial_message_data()
to match its read counterpart, and to reflect its more generic
purpose.

Signed-off-by: Alex Elder <elder@inktank.com>
---
v2: do not move the call to prepare_message_data()

 net/ceph/messenger.c |   63
++++++++++++++++++++++++++++++++------------------
 1 file changed, 41 insertions(+), 22 deletions(-)

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 813c299..8415896 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -1076,7 +1076,7 @@ static void in_msg_pos_next(struct ceph_connection
*con, size_t len,
  *  0 -> socket full, but more to do
  * <0 -> error
  */
-static int write_partial_msg_pages(struct ceph_connection *con)
+static int write_partial_message_data(struct ceph_connection *con)
 {
 	struct ceph_msg *msg = con->out_msg;
 	struct ceph_msg_pos *msg_pos = &con->out_msg_pos;
@@ -1088,7 +1088,7 @@ static int write_partial_msg_pages(struct
ceph_connection *con)
 	const size_t trail_len = (msg->trail ? msg->trail->length : 0);
 	const size_t trail_off = data_len - trail_len;

-	dout("write_partial_msg_pages %p msg %p page %d offset %d\n",
+	dout("%s %p msg %p page %d offset %d\n", __func__,
 	     con, msg, msg_pos->page, msg_pos->page_pos);

 	/*
@@ -1157,7 +1157,7 @@ static int write_partial_msg_pages(struct
ceph_connection *con)
 		out_msg_pos_next(con, page, length, (size_t) ret, in_trail);
 	}

-	dout("write_partial_msg_pages %p msg %p done\n", con, msg);
+	dout("%s %p msg %p done\n", __func__, con, msg);

 	/* prepare and queue up footer, too */
 	if (!do_datacrc)
@@ -1869,13 +1869,44 @@ static int read_partial_message_bio(struct
ceph_connection *con,
 }
 #endif

+static int read_partial_msg_data(struct ceph_connection *con)
+{
+	struct ceph_msg *msg = con->in_msg;
+	struct ceph_msg_pos *msg_pos = &con->in_msg_pos;
+	const bool do_datacrc = !con->msgr->nocrc;
+	unsigned int data_len;
+	int ret = 0;
+
+	BUG_ON(!msg);
+
+	data_len = le32_to_cpu(con->in_hdr.data_len);
+	while (msg_pos->data_pos < data_len) {
+		if (msg->pages) {
+			ret = read_partial_message_pages(con, msg->pages,
+						 data_len, do_datacrc);
+			if (ret <= 0)
+				return ret;
+#ifdef CONFIG_BLOCK
+		} else if (msg->bio) {
+			ret = read_partial_message_bio(con,
+						 data_len, do_datacrc);
+			if (ret <= 0)
+				return ret;
+#endif
+		} else {
+			BUG_ON(1);
+		}
+	}
+
+	return ret;
+}
+
 /*
  * read (part of) a message.
  */
 static int read_partial_message(struct ceph_connection *con)
 {
 	struct ceph_msg *m = con->in_msg;
-	struct ceph_msg_pos *msg_pos = &con->in_msg_pos;
 	int size;
 	int end;
 	int ret;
@@ -1978,22 +2009,10 @@ static int read_partial_message(struct
ceph_connection *con)
 	}

 	/* (page) data */
-	while (msg_pos->data_pos < data_len) {
-		if (m->pages) {
-			ret = read_partial_message_pages(con, m->pages,
-						 data_len, do_datacrc);
-			if (ret <= 0)
-				return ret;
-#ifdef CONFIG_BLOCK
-		} else if (m->bio) {
-			ret = read_partial_message_bio(con,
-						 data_len, do_datacrc);
-			if (ret <= 0)
-				return ret;
-#endif
-		} else {
-			BUG_ON(1);
-		}
+	if (data_len) {
+		ret = read_partial_msg_data(con);
+		if (ret <= 0)
+			return ret;
 	}

 	/* footer */
@@ -2119,13 +2138,13 @@ more_kvec:
 			goto do_next;
 		}

-		ret = write_partial_msg_pages(con);
+		ret = write_partial_message_data(con);
 		if (ret == 1)
 			goto more_kvec;  /* we need to send the footer, too! */
 		if (ret == 0)
 			goto out;
 		if (ret < 0) {
-			dout("try_write write_partial_msg_pages err %d\n",
+			dout("try_write write_partial_message_data err %d\n",
 			     ret);
 			goto out;
 		}
-- 
1.7.9.5