The Ceph messenger would sometimes queue multiple work items to write
data to a socket when the socket buffer was full.
Fix this problem by making ceph_write_space() use SOCK_NOSPACE in the
same way that net/core/stream.c:sk_stream_write_space() does, i.e.,
clearing it only when sufficient space is available in the socket buffer.
Signed-off-by: Jim Schutt <jaschut@xxxxxxxxxx>
---
net/ceph/messenger.c | 18 ++++++++++++------
1 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 67973f0..a4df90b 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -175,16 +175,22 @@ static void ceph_write_space(struct sock *sk)
struct ceph_connection *con =
(struct ceph_connection *)sk->sk_user_data;
- /* only queue to workqueue if there is data we want to write. */
+ /* only queue to workqueue if there is data we want to write,
+ * and there is sufficient space in the socket buffer to accept
+ * more data. clear SOCK_NOSPACE so that ceph_write_space()
+ * doesn't get called again until try_write() fills the socket
+ * buffer. See net/ipv4/tcp_input.c:tcp_check_space()
+ * and net/core/stream.c:sk_stream_write_space().
+ */
if (test_bit(WRITE_PENDING, &con->state)) {
- dout("ceph_write_space %p queueing write work\n", con);
- queue_con(con);
+ if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
+ dout("ceph_write_space %p queueing write work\n", con);
+ clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+ queue_con(con);
+ }
} else {
dout("ceph_write_space %p nothing to write\n", con);
}
-
- /* since we have our own write_space, clear the SOCK_NOSPACE flag */
- clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
}
/* socket's state has changed */
--
1.7.1
--
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