libceph: don't clear bio_iter in prepare_write_message()

At one time it was necessary to clear a message's bio_iter field to
avoid a bad pointer dereference in write_partial_msg_pages().

That no longer seems to be the case.  Here's why.

The message's bio fields represent (in this case) outgoing data.
Between where the bio_iter is made NULL in prepare_write_message()
and the call in that function to prepare_message_data(), the
bio fields are never used.

In prepare_message_data(), init-bio_iter() is called, and the result
of that overwrites the value in the message's bio_iter field.

Because it gets overwritten anyway, there is no need to set it to
NULL.  So don't do it.

This resolves:
    http://tracker.ceph.com/issues/4402

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index e75a03d25c9f3d6f67a57ab926d324ca7abcf184..17d9321b71343a9f50ab3cd43b74b190ba806bb4 100644 (file)
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -804,10 +804,6 @@ static void prepare_write_message(struct ceph_connection *con)
                m->hdr.seq = cpu_to_le64(++con->out_seq);
                m->needs_out_seq = false;
        }
-#ifdef CONFIG_BLOCK
-       else
-               m->bio_iter = NULL;
-#endif
 
        dout("prepare_write_message %p seq %lld type %d len %d+%d+%d (%zd)\n",
             m, con->out_seq, le16_to_cpu(m->hdr.type),