[PATCH 0/3] ceph: messenger: read_partial() cleanups

[PATCH 0/3] ceph: messenger: read_partial() cleanups

[Alex Elder]

This short series adds the use of read_partial() in a few places
that it is not already.  It also gets rid of the in/out "to"
argument (which continues to cause confusion every time I see it),
using an in-only "end" argument in its place.

					-Alex

[PATCH 1/3] ceph: messenger: use read_partial() in read_partial_message()

[Alex Elder]

There are two blocks of code in read_partial_message()--those that
read the header and footer of the message--that can be replaced by a
call to read_partial().  Do that.

Signed-off-by: Alex Elder <elder@inktank.com>
---
  net/ceph/messenger.c |   30 ++++++++++--------------------
  1 file changed, 10 insertions(+), 20 deletions(-)

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index f0993af..673133e 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -1628,7 +1628,7 @@ static int read_partial_message(struct 
ceph_connection *con)
  {
  	struct ceph_msg *m = con->in_msg;
  	int ret;
-	int to, left;
+	int to;
  	unsigned front_len, middle_len, data_len;
  	bool do_datacrc = !con->msgr->nocrc;
  	int skip;
@@ -1638,15 +1638,10 @@ static int read_partial_message(struct 
ceph_connection *con)
  	dout("read_partial_message con %p msg %p\n", con, m);

  	/* header */
-	while (con->in_base_pos < sizeof(con->in_hdr)) {
-		left = sizeof(con->in_hdr) - con->in_base_pos;
-		ret = ceph_tcp_recvmsg(con->sock,
-				       (char *)&con->in_hdr + con->in_base_pos,
-				       left);
-		if (ret <= 0)
-			return ret;
-		con->in_base_pos += ret;
-	}
+	to = 0;
+	ret = read_partial(con, &to, sizeof (con->in_hdr), &con->in_hdr);
+	if (ret <= 0)
+		return ret;

  	crc = crc32c(0, &con->in_hdr, offsetof(struct ceph_msg_header, crc));
  	if (cpu_to_le32(crc) != con->in_hdr.crc) {
@@ -1759,16 +1754,11 @@ static int read_partial_message(struct 
ceph_connection *con)
  	}

  	/* footer */
-	to = sizeof(m->hdr) + sizeof(m->footer);
-	while (con->in_base_pos < to) {
-		left = to - con->in_base_pos;
-		ret = ceph_tcp_recvmsg(con->sock, (char *)&m->footer +
-				       (con->in_base_pos - sizeof(m->hdr)),
-				       left);
-		if (ret <= 0)
-			return ret;
-		con->in_base_pos += ret;
-	}
+	to = sizeof (m->hdr);
+	ret = read_partial(con, &to, sizeof (m->footer), &m->footer);
+	if (ret <= 0)
+		return ret;
+
  	dout("read_partial_message got msg %p %d (%u) + %d (%u) + %d (%u)\n",
  	     m, front_len, m->footer.front_crc, middle_len,
  	     m->footer.middle_crc, data_len, m->footer.data_crc);
-- 
1.7.9.5

Re: [PATCH 1/3] ceph: messenger: use read_partial() in read_partial_message()

[Sage Weil]

Reviewed-by: Sage Weil <sage@inktank.com>

On Thu, 10 May 2012, Alex Elder wrote:

> There are two blocks of code in read_partial_message()--those that
> read the header and footer of the message--that can be replaced by a
> call to read_partial().  Do that.
> 
> Signed-off-by: Alex Elder <elder@inktank.com>
> ---
>  net/ceph/messenger.c |   30 ++++++++++--------------------
>  1 file changed, 10 insertions(+), 20 deletions(-)
> 
> diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> index f0993af..673133e 100644
> --- a/net/ceph/messenger.c
> +++ b/net/ceph/messenger.c
> @@ -1628,7 +1628,7 @@ static int read_partial_message(struct ceph_connection
> *con)
>  {
>  	struct ceph_msg *m = con->in_msg;
>  	int ret;
> -	int to, left;
> +	int to;
>  	unsigned front_len, middle_len, data_len;
>  	bool do_datacrc = !con->msgr->nocrc;
>  	int skip;
> @@ -1638,15 +1638,10 @@ static int read_partial_message(struct ceph_connection
> *con)
>  	dout("read_partial_message con %p msg %p\n", con, m);
> 
>  	/* header */
> -	while (con->in_base_pos < sizeof(con->in_hdr)) {
> -		left = sizeof(con->in_hdr) - con->in_base_pos;
> -		ret = ceph_tcp_recvmsg(con->sock,
> -				       (char *)&con->in_hdr +
> con->in_base_pos,
> -				       left);
> -		if (ret <= 0)
> -			return ret;
> -		con->in_base_pos += ret;
> -	}
> +	to = 0;
> +	ret = read_partial(con, &to, sizeof (con->in_hdr), &con->in_hdr);
> +	if (ret <= 0)
> +		return ret;
> 
>  	crc = crc32c(0, &con->in_hdr, offsetof(struct ceph_msg_header, crc));
>  	if (cpu_to_le32(crc) != con->in_hdr.crc) {
> @@ -1759,16 +1754,11 @@ static int read_partial_message(struct ceph_connection
> *con)
>  	}
> 
>  	/* footer */
> -	to = sizeof(m->hdr) + sizeof(m->footer);
> -	while (con->in_base_pos < to) {
> -		left = to - con->in_base_pos;
> -		ret = ceph_tcp_recvmsg(con->sock, (char *)&m->footer +
> -				       (con->in_base_pos - sizeof(m->hdr)),
> -				       left);
> -		if (ret <= 0)
> -			return ret;
> -		con->in_base_pos += ret;
> -	}
> +	to = sizeof (m->hdr);
> +	ret = read_partial(con, &to, sizeof (m->footer), &m->footer);
> +	if (ret <= 0)
> +		return ret;
> +
>  	dout("read_partial_message got msg %p %d (%u) + %d (%u) + %d (%u)\n",
>  	     m, front_len, m->footer.front_crc, middle_len,
>  	     m->footer.middle_crc, data_len, m->footer.data_crc);
> -- 
> 1.7.9.5
> 
> --
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> 

[PATCH 2/3] ceph: messenger: update "to" in read_partial() caller

[Alex Elder]

read_partial() always increases whatever "to" value is supplied by
adding the requested size to it.  That's the only thing it does with
that pointed-to value.

Do that pointer advance in the caller (and then only when the
updated value will be subsequently used), and change the "to"
parameter to be an in-only and non-pointer value.

Signed-off-by: Alex Elder <elder@inktank.com>
---
  net/ceph/messenger.c |   31 ++++++++++++++++---------------
  1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 673133e..37fd2ae 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -992,11 +992,12 @@ static int prepare_read_message(struct 
ceph_connection *con)


  static int read_partial(struct ceph_connection *con,
-			int *to, int size, void *object)
+			int to, int size, void *object)
  {
-	*to += size;
-	while (con->in_base_pos < *to) {
-		int left = *to - con->in_base_pos;
+	int end = to + size;
+
+	while (con->in_base_pos < end) {
+		int left = end - con->in_base_pos;
  		int have = size - left;
  		int ret = ceph_tcp_recvmsg(con->sock, object + have, left);
  		if (ret <= 0)
@@ -1017,14 +1018,16 @@ static int read_partial_banner(struct 
ceph_connection *con)
  	dout("read_partial_banner %p at %d\n", con, con->in_base_pos);

  	/* peer's banner */
-	ret = read_partial(con, &to, strlen(CEPH_BANNER), con->in_banner);
+	ret = read_partial(con, to, strlen(CEPH_BANNER), con->in_banner);
  	if (ret <= 0)
  		goto out;
-	ret = read_partial(con, &to, sizeof(con->actual_peer_addr),
+	to += strlen(CEPH_BANNER);
+	ret = read_partial(con, to, sizeof(con->actual_peer_addr),
  			   &con->actual_peer_addr);
  	if (ret <= 0)
  		goto out;
-	ret = read_partial(con, &to, sizeof(con->peer_addr_for_me),
+	to += sizeof(con->actual_peer_addr);
+	ret = read_partial(con, to, sizeof(con->peer_addr_for_me),
  			   &con->peer_addr_for_me);
  	if (ret <= 0)
  		goto out;
@@ -1038,10 +1041,11 @@ static int read_partial_connect(struct 
ceph_connection *con)

  	dout("read_partial_connect %p at %d\n", con, con->in_base_pos);

-	ret = read_partial(con, &to, sizeof(con->in_reply), &con->in_reply);
+	ret = read_partial(con, to, sizeof(con->in_reply), &con->in_reply);
  	if (ret <= 0)
  		goto out;
-	ret = read_partial(con, &to, le32_to_cpu(con->in_reply.authorizer_len),
+	to += sizeof(con->in_reply);
+	ret = read_partial(con, to, le32_to_cpu(con->in_reply.authorizer_len),
  			   con->auth_reply_buf);
  	if (ret <= 0)
  		goto out;
@@ -1491,9 +1495,7 @@ static int process_connect(struct ceph_connection 
*con)
   */
  static int read_partial_ack(struct ceph_connection *con)
  {
-	int to = 0;
-
-	return read_partial(con, &to, sizeof(con->in_temp_ack),
+	return read_partial(con, 0, sizeof(con->in_temp_ack),
  			    &con->in_temp_ack);
  }

@@ -1638,8 +1640,7 @@ static int read_partial_message(struct 
ceph_connection *con)
  	dout("read_partial_message con %p msg %p\n", con, m);

  	/* header */
-	to = 0;
-	ret = read_partial(con, &to, sizeof (con->in_hdr), &con->in_hdr);
+	ret = read_partial(con, 0, sizeof (con->in_hdr), &con->in_hdr);
  	if (ret <= 0)
  		return ret;

@@ -1755,7 +1756,7 @@ static int read_partial_message(struct 
ceph_connection *con)

  	/* footer */
  	to = sizeof (m->hdr);
-	ret = read_partial(con, &to, sizeof (m->footer), &m->footer);
+	ret = read_partial(con, to, sizeof (m->footer), &m->footer);
  	if (ret <= 0)
  		return ret;

-- 
1.7.9.5

Re: [PATCH 2/3] ceph: messenger: update "to" in read_partial() caller

[Sage Weil]

Reviewed-by: Sage Weil <sage@inktank.com>

On Thu, 10 May 2012, Alex Elder wrote:

> read_partial() always increases whatever "to" value is supplied by
> adding the requested size to it.  That's the only thing it does with
> that pointed-to value.
> 
> Do that pointer advance in the caller (and then only when the
> updated value will be subsequently used), and change the "to"
> parameter to be an in-only and non-pointer value.
> 
> Signed-off-by: Alex Elder <elder@inktank.com>
> ---
>  net/ceph/messenger.c |   31 ++++++++++++++++---------------
>  1 file changed, 16 insertions(+), 15 deletions(-)
> 
> diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> index 673133e..37fd2ae 100644
> --- a/net/ceph/messenger.c
> +++ b/net/ceph/messenger.c
> @@ -992,11 +992,12 @@ static int prepare_read_message(struct ceph_connection
> *con)
> 
> 
>  static int read_partial(struct ceph_connection *con,
> -			int *to, int size, void *object)
> +			int to, int size, void *object)
>  {
> -	*to += size;
> -	while (con->in_base_pos < *to) {
> -		int left = *to - con->in_base_pos;
> +	int end = to + size;
> +
> +	while (con->in_base_pos < end) {
> +		int left = end - con->in_base_pos;
>  		int have = size - left;
>  		int ret = ceph_tcp_recvmsg(con->sock, object + have, left);
>  		if (ret <= 0)
> @@ -1017,14 +1018,16 @@ static int read_partial_banner(struct ceph_connection
> *con)
>  	dout("read_partial_banner %p at %d\n", con, con->in_base_pos);
> 
>  	/* peer's banner */
> -	ret = read_partial(con, &to, strlen(CEPH_BANNER), con->in_banner);
> +	ret = read_partial(con, to, strlen(CEPH_BANNER), con->in_banner);
>  	if (ret <= 0)
>  		goto out;
> -	ret = read_partial(con, &to, sizeof(con->actual_peer_addr),
> +	to += strlen(CEPH_BANNER);
> +	ret = read_partial(con, to, sizeof(con->actual_peer_addr),
>  			   &con->actual_peer_addr);
>  	if (ret <= 0)
>  		goto out;
> -	ret = read_partial(con, &to, sizeof(con->peer_addr_for_me),
> +	to += sizeof(con->actual_peer_addr);
> +	ret = read_partial(con, to, sizeof(con->peer_addr_for_me),
>  			   &con->peer_addr_for_me);
>  	if (ret <= 0)
>  		goto out;
> @@ -1038,10 +1041,11 @@ static int read_partial_connect(struct ceph_connection
> *con)
> 
>  	dout("read_partial_connect %p at %d\n", con, con->in_base_pos);
> 
> -	ret = read_partial(con, &to, sizeof(con->in_reply), &con->in_reply);
> +	ret = read_partial(con, to, sizeof(con->in_reply), &con->in_reply);
>  	if (ret <= 0)
>  		goto out;
> -	ret = read_partial(con, &to,
> le32_to_cpu(con->in_reply.authorizer_len),
> +	to += sizeof(con->in_reply);
> +	ret = read_partial(con, to, le32_to_cpu(con->in_reply.authorizer_len),
>  			   con->auth_reply_buf);
>  	if (ret <= 0)
>  		goto out;
> @@ -1491,9 +1495,7 @@ static int process_connect(struct ceph_connection *con)
>   */
>  static int read_partial_ack(struct ceph_connection *con)
>  {
> -	int to = 0;
> -
> -	return read_partial(con, &to, sizeof(con->in_temp_ack),
> +	return read_partial(con, 0, sizeof(con->in_temp_ack),
>  			    &con->in_temp_ack);
>  }
> 
> @@ -1638,8 +1640,7 @@ static int read_partial_message(struct ceph_connection
> *con)
>  	dout("read_partial_message con %p msg %p\n", con, m);
> 
>  	/* header */
> -	to = 0;
> -	ret = read_partial(con, &to, sizeof (con->in_hdr), &con->in_hdr);
> +	ret = read_partial(con, 0, sizeof (con->in_hdr), &con->in_hdr);
>  	if (ret <= 0)
>  		return ret;
> 
> @@ -1755,7 +1756,7 @@ static int read_partial_message(struct ceph_connection
> *con)
> 
>  	/* footer */
>  	to = sizeof (m->hdr);
> -	ret = read_partial(con, &to, sizeof (m->footer), &m->footer);
> +	ret = read_partial(con, to, sizeof (m->footer), &m->footer);
>  	if (ret <= 0)
>  		return ret;
> 
> -- 
> 1.7.9.5
> 
> --
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> 

[PATCH 3/3] ceph: messenger: change read_partial() to take "end" arg

[Alex Elder]

Make the second argument to read_partial() be the ending input byte
position rather than the beginning offset it now represents.  This
amounts to moving the addition "to + size" into the caller.

Signed-off-by: Alex Elder <elder@inktank.com>
---
  net/ceph/messenger.c |   59 
++++++++++++++++++++++++++++++++------------------
  1 file changed, 38 insertions(+), 21 deletions(-)

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 37fd2ae..364c902 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -992,10 +992,8 @@ static int prepare_read_message(struct 
ceph_connection *con)


  static int read_partial(struct ceph_connection *con,
-			int to, int size, void *object)
+			int end, int size, void *object)
  {
-	int end = to + size;
-
  	while (con->in_base_pos < end) {
  		int left = end - con->in_base_pos;
  		int have = size - left;
@@ -1013,40 +1011,52 @@ static int read_partial(struct ceph_connection *con,
   */
  static int read_partial_banner(struct ceph_connection *con)
  {
-	int ret, to = 0;
+	int size;
+	int end;
+	int ret;

  	dout("read_partial_banner %p at %d\n", con, con->in_base_pos);

  	/* peer's banner */
-	ret = read_partial(con, to, strlen(CEPH_BANNER), con->in_banner);
+	size = strlen(CEPH_BANNER);
+	end = size;
+	ret = read_partial(con, end, size, con->in_banner);
  	if (ret <= 0)
  		goto out;
-	to += strlen(CEPH_BANNER);
-	ret = read_partial(con, to, sizeof(con->actual_peer_addr),
-			   &con->actual_peer_addr);
+
+	size = sizeof (con->actual_peer_addr);
+	end += size;
+	ret = read_partial(con, end, size, &con->actual_peer_addr);
  	if (ret <= 0)
  		goto out;
-	to += sizeof(con->actual_peer_addr);
-	ret = read_partial(con, to, sizeof(con->peer_addr_for_me),
-			   &con->peer_addr_for_me);
+
+	size = sizeof (con->peer_addr_for_me);
+	end += size;
+	ret = read_partial(con, end, size, &con->peer_addr_for_me);
  	if (ret <= 0)
  		goto out;
+
  out:
  	return ret;
  }

  static int read_partial_connect(struct ceph_connection *con)
  {
-	int ret, to = 0;
+	int size;
+	int end;
+	int ret;

  	dout("read_partial_connect %p at %d\n", con, con->in_base_pos);

-	ret = read_partial(con, to, sizeof(con->in_reply), &con->in_reply);
+	size = sizeof (con->in_reply);
+	end = size;
+	ret = read_partial(con, end, size, &con->in_reply);
  	if (ret <= 0)
  		goto out;
-	to += sizeof(con->in_reply);
-	ret = read_partial(con, to, le32_to_cpu(con->in_reply.authorizer_len),
-			   con->auth_reply_buf);
+
+	size = le32_to_cpu(con->in_reply.authorizer_len);
+	end += size;
+	ret = read_partial(con, end, size, con->auth_reply_buf);
  	if (ret <= 0)
  		goto out;

@@ -1495,8 +1505,10 @@ static int process_connect(struct ceph_connection 
*con)
   */
  static int read_partial_ack(struct ceph_connection *con)
  {
-	return read_partial(con, 0, sizeof(con->in_temp_ack),
-			    &con->in_temp_ack);
+	int size = sizeof (con->in_temp_ack);
+	int end = size;
+
+	return read_partial(con, end, size, &con->in_temp_ack);
  }


@@ -1629,6 +1641,8 @@ static int read_partial_message_bio(struct 
ceph_connection *con,
  static int read_partial_message(struct ceph_connection *con)
  {
  	struct ceph_msg *m = con->in_msg;
+	int size;
+	int end;
  	int ret;
  	int to;
  	unsigned front_len, middle_len, data_len;
@@ -1640,7 +1654,9 @@ static int read_partial_message(struct 
ceph_connection *con)
  	dout("read_partial_message con %p msg %p\n", con, m);

  	/* header */
-	ret = read_partial(con, 0, sizeof (con->in_hdr), &con->in_hdr);
+	size = sizeof (con->in_hdr);
+	end = size;
+	ret = read_partial(con, end, size, &con->in_hdr);
  	if (ret <= 0)
  		return ret;

@@ -1755,8 +1771,9 @@ static int read_partial_message(struct 
ceph_connection *con)
  	}

  	/* footer */
-	to = sizeof (m->hdr);
-	ret = read_partial(con, to, sizeof (m->footer), &m->footer);
+	size = sizeof (m->footer);
+	end += size;
+	ret = read_partial(con, end, size, &m->footer);
  	if (ret <= 0)
  		return ret;

-- 
1.7.9.5

Re: [PATCH 3/3] ceph: messenger: change read_partial() to take "end" arg

[Sage Weil]

This looks correct, but seems like a more confusing calling convention 
to me.  Before this patch it's basically a (start, len) logical 
range in the input stream.. after it's (end, len).  It also seems to be 
more code?

sage

On Thu, 10 May 2012, Alex Elder wrote:

> Make the second argument to read_partial() be the ending input byte
> position rather than the beginning offset it now represents.  This
> amounts to moving the addition "to + size" into the caller.
> 
> Signed-off-by: Alex Elder <elder@inktank.com>
> ---
>  net/ceph/messenger.c |   59
> ++++++++++++++++++++++++++++++++------------------
>  1 file changed, 38 insertions(+), 21 deletions(-)
> 
> diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> index 37fd2ae..364c902 100644
> --- a/net/ceph/messenger.c
> +++ b/net/ceph/messenger.c
> @@ -992,10 +992,8 @@ static int prepare_read_message(struct ceph_connection
> *con)
> 
> 
>  static int read_partial(struct ceph_connection *con,
> -			int to, int size, void *object)
> +			int end, int size, void *object)
>  {
> -	int end = to + size;
> -
>  	while (con->in_base_pos < end) {
>  		int left = end - con->in_base_pos;
>  		int have = size - left;
> @@ -1013,40 +1011,52 @@ static int read_partial(struct ceph_connection *con,
>   */
>  static int read_partial_banner(struct ceph_connection *con)
>  {
> -	int ret, to = 0;
> +	int size;
> +	int end;
> +	int ret;
> 
>  	dout("read_partial_banner %p at %d\n", con, con->in_base_pos);
> 
>  	/* peer's banner */
> -	ret = read_partial(con, to, strlen(CEPH_BANNER), con->in_banner);
> +	size = strlen(CEPH_BANNER);
> +	end = size;
> +	ret = read_partial(con, end, size, con->in_banner);
>  	if (ret <= 0)
>  		goto out;
> -	to += strlen(CEPH_BANNER);
> -	ret = read_partial(con, to, sizeof(con->actual_peer_addr),
> -			   &con->actual_peer_addr);
> +
> +	size = sizeof (con->actual_peer_addr);
> +	end += size;
> +	ret = read_partial(con, end, size, &con->actual_peer_addr);
>  	if (ret <= 0)
>  		goto out;
> -	to += sizeof(con->actual_peer_addr);
> -	ret = read_partial(con, to, sizeof(con->peer_addr_for_me),
> -			   &con->peer_addr_for_me);
> +
> +	size = sizeof (con->peer_addr_for_me);
> +	end += size;
> +	ret = read_partial(con, end, size, &con->peer_addr_for_me);
>  	if (ret <= 0)
>  		goto out;
> +
>  out:
>  	return ret;
>  }
> 
>  static int read_partial_connect(struct ceph_connection *con)
>  {
> -	int ret, to = 0;
> +	int size;
> +	int end;
> +	int ret;
> 
>  	dout("read_partial_connect %p at %d\n", con, con->in_base_pos);
> 
> -	ret = read_partial(con, to, sizeof(con->in_reply), &con->in_reply);
> +	size = sizeof (con->in_reply);
> +	end = size;
> +	ret = read_partial(con, end, size, &con->in_reply);
>  	if (ret <= 0)
>  		goto out;
> -	to += sizeof(con->in_reply);
> -	ret = read_partial(con, to, le32_to_cpu(con->in_reply.authorizer_len),
> -			   con->auth_reply_buf);
> +
> +	size = le32_to_cpu(con->in_reply.authorizer_len);
> +	end += size;
> +	ret = read_partial(con, end, size, con->auth_reply_buf);
>  	if (ret <= 0)
>  		goto out;
> 
> @@ -1495,8 +1505,10 @@ static int process_connect(struct ceph_connection *con)
>   */
>  static int read_partial_ack(struct ceph_connection *con)
>  {
> -	return read_partial(con, 0, sizeof(con->in_temp_ack),
> -			    &con->in_temp_ack);
> +	int size = sizeof (con->in_temp_ack);
> +	int end = size;
> +
> +	return read_partial(con, end, size, &con->in_temp_ack);
>  }
> 
> 
> @@ -1629,6 +1641,8 @@ static int read_partial_message_bio(struct
> ceph_connection *con,
>  static int read_partial_message(struct ceph_connection *con)
>  {
>  	struct ceph_msg *m = con->in_msg;
> +	int size;
> +	int end;
>  	int ret;
>  	int to;
>  	unsigned front_len, middle_len, data_len;
> @@ -1640,7 +1654,9 @@ static int read_partial_message(struct ceph_connection
> *con)
>  	dout("read_partial_message con %p msg %p\n", con, m);
> 
>  	/* header */
> -	ret = read_partial(con, 0, sizeof (con->in_hdr), &con->in_hdr);
> +	size = sizeof (con->in_hdr);
> +	end = size;
> +	ret = read_partial(con, end, size, &con->in_hdr);
>  	if (ret <= 0)
>  		return ret;
> 
> @@ -1755,8 +1771,9 @@ static int read_partial_message(struct ceph_connection
> *con)
>  	}
> 
>  	/* footer */
> -	to = sizeof (m->hdr);
> -	ret = read_partial(con, to, sizeof (m->footer), &m->footer);
> +	size = sizeof (m->footer);
> +	end += size;
> +	ret = read_partial(con, end, size, &m->footer);
>  	if (ret <= 0)
>  		return ret;
> 
> -- 
> 1.7.9.5
> 
> --
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> 

Re: [PATCH 3/3] ceph: messenger: change read_partial() to take "end" arg

[Alex Elder]

On 05/12/2012 07:11 PM, Sage Weil wrote:
> This looks correct, but seems like a more confusing calling convention
> to me.  Before this patch it's basically a (start, len) logical
> range in the input stream.. after it's (end, len).  It also seems to be
> more code?

I'm trying to make this code more understandable.  I have this
ongoing confusion with what the meaning of "to" is.  It may be
that it was a "start" position, in which case, "start" might be
a better name, and maybe just renaming it would have been better.

However, another source of confusion here is what the meaning of
this "start" would be versus the meaning of con->in_base_pos.
The actual input position is defined by in_base_pos, while "start"
would represent the start of the partially-filled portion of a
message we're now working on reading.  Where that starts is
irrelevant, and I found the existence of something called "start"
to be distracting and ambiguous.  It's a lot easier to wrap my
head around it by just providing the end position for the read
and leaving out any (other) notion of the "start" position
entirely.

So yes, it expands to a bit more code in the caller but the
result is something I can more easily understand and therefore
believe in.  (I also hope that some later refactoring may make
whatever excess this produces go away, or be less glaring anyway.)

					-Alex

> sage
>
> On Thu, 10 May 2012, Alex Elder wrote:
>
>> Make the second argument to read_partial() be the ending input byte
>> position rather than the beginning offset it now represents.  This
>> amounts to moving the addition "to + size" into the caller.
>>
>> Signed-off-by: Alex Elder<elder@inktank.com>
>> ---
>>   net/ceph/messenger.c |   59
>> ++++++++++++++++++++++++++++++++------------------
>>   1 file changed, 38 insertions(+), 21 deletions(-)
>>
>> diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
>> index 37fd2ae..364c902 100644
>> --- a/net/ceph/messenger.c
>> +++ b/net/ceph/messenger.c
>> @@ -992,10 +992,8 @@ static int prepare_read_message(struct ceph_connection
>> *con)
>>
>>
>>   static int read_partial(struct ceph_connection *con,
>> -			int to, int size, void *object)
>> +			int end, int size, void *object)
>>   {
>> -	int end = to + size;
>> -
>>   	while (con->in_base_pos<  end) {
>>   		int left = end - con->in_base_pos;
>>   		int have = size - left;
>> @@ -1013,40 +1011,52 @@ static int read_partial(struct ceph_connection *con,
>>    */
>>   static int read_partial_banner(struct ceph_connection *con)
>>   {
>> -	int ret, to = 0;
>> +	int size;
>> +	int end;
>> +	int ret;
>>
>>   	dout("read_partial_banner %p at %d\n", con, con->in_base_pos);
>>
>>   	/* peer's banner */
>> -	ret = read_partial(con, to, strlen(CEPH_BANNER), con->in_banner);
>> +	size = strlen(CEPH_BANNER);
>> +	end = size;
>> +	ret = read_partial(con, end, size, con->in_banner);
>>   	if (ret<= 0)
>>   		goto out;
>> -	to += strlen(CEPH_BANNER);
>> -	ret = read_partial(con, to, sizeof(con->actual_peer_addr),
>> -			&con->actual_peer_addr);
>> +
>> +	size = sizeof (con->actual_peer_addr);
>> +	end += size;
>> +	ret = read_partial(con, end, size,&con->actual_peer_addr);
>>   	if (ret<= 0)
>>   		goto out;
>> -	to += sizeof(con->actual_peer_addr);
>> -	ret = read_partial(con, to, sizeof(con->peer_addr_for_me),
>> -			&con->peer_addr_for_me);
>> +
>> +	size = sizeof (con->peer_addr_for_me);
>> +	end += size;
>> +	ret = read_partial(con, end, size,&con->peer_addr_for_me);
>>   	if (ret<= 0)
>>   		goto out;
>> +
>>   out:
>>   	return ret;
>>   }
>>
>>   static int read_partial_connect(struct ceph_connection *con)
>>   {
>> -	int ret, to = 0;
>> +	int size;
>> +	int end;
>> +	int ret;
>>
>>   	dout("read_partial_connect %p at %d\n", con, con->in_base_pos);
>>
>> -	ret = read_partial(con, to, sizeof(con->in_reply),&con->in_reply);
>> +	size = sizeof (con->in_reply);
>> +	end = size;
>> +	ret = read_partial(con, end, size,&con->in_reply);
>>   	if (ret<= 0)
>>   		goto out;
>> -	to += sizeof(con->in_reply);
>> -	ret = read_partial(con, to, le32_to_cpu(con->in_reply.authorizer_len),
>> -			   con->auth_reply_buf);
>> +
>> +	size = le32_to_cpu(con->in_reply.authorizer_len);
>> +	end += size;
>> +	ret = read_partial(con, end, size, con->auth_reply_buf);
>>   	if (ret<= 0)
>>   		goto out;
>>
>> @@ -1495,8 +1505,10 @@ static int process_connect(struct ceph_connection *con)
>>    */
>>   static int read_partial_ack(struct ceph_connection *con)
>>   {
>> -	return read_partial(con, 0, sizeof(con->in_temp_ack),
>> -			&con->in_temp_ack);
>> +	int size = sizeof (con->in_temp_ack);
>> +	int end = size;
>> +
>> +	return read_partial(con, end, size,&con->in_temp_ack);
>>   }
>>
>>
>> @@ -1629,6 +1641,8 @@ static int read_partial_message_bio(struct
>> ceph_connection *con,
>>   static int read_partial_message(struct ceph_connection *con)
>>   {
>>   	struct ceph_msg *m = con->in_msg;
>> +	int size;
>> +	int end;
>>   	int ret;
>>   	int to;
>>   	unsigned front_len, middle_len, data_len;
>> @@ -1640,7 +1654,9 @@ static int read_partial_message(struct ceph_connection
>> *con)
>>   	dout("read_partial_message con %p msg %p\n", con, m);
>>
>>   	/* header */
>> -	ret = read_partial(con, 0, sizeof (con->in_hdr),&con->in_hdr);
>> +	size = sizeof (con->in_hdr);
>> +	end = size;
>> +	ret = read_partial(con, end, size,&con->in_hdr);
>>   	if (ret<= 0)
>>   		return ret;
>>
>> @@ -1755,8 +1771,9 @@ static int read_partial_message(struct ceph_connection
>> *con)
>>   	}
>>
>>   	/* footer */
>> -	to = sizeof (m->hdr);
>> -	ret = read_partial(con, to, sizeof (m->footer),&m->footer);
>> +	size = sizeof (m->footer);
>> +	end += size;
>> +	ret = read_partial(con, end, size,&m->footer);
>>   	if (ret<= 0)
>>   		return ret;
>>
>> --
>> 1.7.9.5
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>>
>

Re: [PATCH 3/3] ceph: messenger: change read_partial() to take "end" arg

[Alex Elder]

On 05/12/2012 07:11 PM, Sage Weil wrote:
> This looks correct, but seems like a more confusing calling convention
> to me.  Before this patch it's basically a (start, len) logical
> range in the input stream.. after it's (end, len).  It also seems to be
> more code?
>
> sage
>
> On Thu, 10 May 2012, Alex Elder wrote:
>
>> Make the second argument to read_partial() be the ending input byte
>> position rather than the beginning offset it now represents.  This
>> amounts to moving the addition "to + size" into the caller.
>>
>> Signed-off-by: Alex Elder<elder@inktank.com>
>> ---

Note that this patch also left the local variable "to" in
read_partial_message() unused.  I'll delete its definition
before I commit.

Thanks for the review.

					-Alex

. . .
>> @@ -1755,8 +1771,9 @@ static int read_partial_message(struct ceph_connection
>> *con)
>>   	}
>>
>>   	/* footer */
>> -	to = sizeof (m->hdr);
>> -	ret = read_partial(con, to, sizeof (m->footer),&m->footer);
>> +	size = sizeof (m->footer);
>> +	end += size;
>> +	ret = read_partial(con, end, size,&m->footer);
>>   	if (ret<= 0)
>>   		return ret;
>>
>> --
>> 1.7.9.5
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>>
>