[RFC PATCH 4/5] libceph: add revoke support for sparse data

[Jeff Layton <jlayton@xxxxxxxxxx>]

Since sparse read handling is so complex, add a new field for tracking
how much data we've read out of the data blob, and decrement that
whenever we marshal up a new iov_iter for a read off the socket.

On a revoke, just ensure we skip past whatever remains in the iter, plus
the remaining data_len and epilogue.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
 include/linux/ceph/messenger.h |  1 +
 net/ceph/messenger_v2.c        | 37 +++++++++++++++++++++++++++++++---
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
index 498a1b7bd3c1..206452d8a385 100644
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -413,6 +413,7 @@ struct ceph_connection_v2_info {
 
 	void *conn_bufs[16];
 	int conn_buf_cnt;
+	int data_len_remain;
 
 	struct kvec in_sign_kvecs[8];
 	struct kvec out_sign_kvecs[8];
diff --git a/net/ceph/messenger_v2.c b/net/ceph/messenger_v2.c
index 16fcac363670..45ba59ce69e6 100644
--- a/net/ceph/messenger_v2.c
+++ b/net/ceph/messenger_v2.c
@@ -1866,6 +1866,7 @@ static int prepare_sparse_read_cont(struct ceph_connection *con)
 			bv.bv_offset = 0;
 		}
 		set_in_bvec(con, &bv);
+		con->v2.data_len_remain -= bv.bv_len;
 		WARN_ON(con->v2.in_state != IN_S_PREPARE_SPARSE_DATA_CONT);
 		return 0;
 	}
@@ -1882,7 +1883,10 @@ static int prepare_sparse_read_cont(struct ceph_connection *con)
 		return 0;
 	}
 
-	return prepare_read_data_extent(con, off, len);
+	ret = prepare_read_data_extent(con, off, len);
+	if (ret == 0)
+		con->v2.data_len_remain -= len;
+	return ret;
 }
 
 static int prepare_sparse_read_header(struct ceph_connection *con)
@@ -1918,19 +1922,24 @@ static int prepare_sparse_read_header(struct ceph_connection *con)
 
 	if (!buf) {
 		ret = prepare_read_data_extent(con, off, len);
-		if (!ret)
+		if (!ret) {
+			con->v2.data_len_remain -= len;
 			con->v2.in_state = IN_S_PREPARE_SPARSE_DATA_CONT;
+		}
 		return ret;
 	}
 
 	WARN_ON_ONCE(con->v2.in_state != IN_S_PREPARE_SPARSE_DATA_HDR);
 	reset_in_kvecs(con);
 	add_in_kvec(con, buf, len);
+	con->v2.data_len_remain -= len;
 	return 0;
 }
 
 static int prepare_sparse_read_data(struct ceph_connection *con)
 {
+	struct ceph_msg *msg = con->in_msg;
+
 	if (WARN_ON_ONCE(!con->ops->sparse_read))
 		return -EOPNOTSUPP;
 
@@ -1939,6 +1948,7 @@ static int prepare_sparse_read_data(struct ceph_connection *con)
 
 	reset_in_kvecs(con);
 	con->v2.in_state = IN_S_PREPARE_SPARSE_DATA_HDR;
+	con->v2.data_len_remain = data_len(msg);
 	return prepare_sparse_read_header(con);
 }
 
@@ -3620,6 +3630,23 @@ static void revoke_at_prepare_read_enc_page(struct ceph_connection *con)
 	con->v2.in_state = IN_S_FINISH_SKIP;
 }
 
+static void revoke_at_prepare_sparse_data(struct ceph_connection *con)
+{
+	int resid;  /* current piece of data */
+	int remaining;
+
+	WARN_ON(con_secure(con));
+	WARN_ON(!data_len(con->in_msg));
+	WARN_ON(!iov_iter_is_bvec(&con->v2.in_iter));
+	resid = iov_iter_count(&con->v2.in_iter);
+	dout("%s con %p resid %d\n", __func__, con, resid);
+
+	remaining = CEPH_EPILOGUE_PLAIN_LEN + con->v2.data_len_remain;
+	con->v2.in_iter.count -= resid;
+	set_in_skip(con, resid + remaining);
+	con->v2.in_state = IN_S_FINISH_SKIP;
+}
+
 static void revoke_at_handle_epilogue(struct ceph_connection *con)
 {
 	int resid;
@@ -3636,7 +3663,7 @@ static void revoke_at_handle_epilogue(struct ceph_connection *con)
 void ceph_con_v2_revoke_incoming(struct ceph_connection *con)
 {
 	switch (con->v2.in_state) {
-	case IN_S_PREPARE_SPARSE_DATA:		// FIXME
+	case IN_S_PREPARE_SPARSE_DATA:
 	case IN_S_PREPARE_READ_DATA:
 		revoke_at_prepare_read_data(con);
 		break;
@@ -3646,6 +3673,10 @@ void ceph_con_v2_revoke_incoming(struct ceph_connection *con)
 	case IN_S_PREPARE_READ_ENC_PAGE:
 		revoke_at_prepare_read_enc_page(con);
 		break;
+	case IN_S_PREPARE_SPARSE_DATA_HDR:
+	case IN_S_PREPARE_SPARSE_DATA_CONT:
+		revoke_at_prepare_sparse_data(con);
+		break;
 	case IN_S_HANDLE_EPILOGUE:
 		revoke_at_handle_epilogue(con);
 		break;
-- 
2.34.1