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ceph: preserve seq # on requeued messages after transient transport e…
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…rrors

If the tcp connection drops and we reconnect to reestablish a stateful
session (with the mds), we need to resend previously sent (and possibly
received) messages with the _same_ seq # so that they can be dropped on
the other end if needed.  Only assign a new seq once after the message is
queued.

Signed-off-by: Sage Weil <sage@newdream.net>
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Sage Weil committed May 12, 2010
1 parent f818a73 commit e84346b
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Showing 2 changed files with 11 additions and 1 deletion.
11 changes: 10 additions & 1 deletion fs/ceph/messenger.c
Original file line number Diff line number Diff line change
Expand Up @@ -492,7 +492,14 @@ static void prepare_write_message(struct ceph_connection *con)
list_move_tail(&m->list_head, &con->out_sent);
}

m->hdr.seq = cpu_to_le64(++con->out_seq);
/*
* only assign outgoing seq # if we haven't sent this message
* yet. if it is requeued, resend with it's original seq.
*/
if (m->needs_out_seq) {
m->hdr.seq = cpu_to_le64(++con->out_seq);
m->needs_out_seq = false;
}

dout("prepare_write_message %p seq %lld type %d len %d+%d+%d %d pgs\n",
m, con->out_seq, le16_to_cpu(m->hdr.type),
Expand Down Expand Up @@ -1986,6 +1993,8 @@ void ceph_con_send(struct ceph_connection *con, struct ceph_msg *msg)

BUG_ON(msg->front.iov_len != le32_to_cpu(msg->hdr.front_len));

msg->needs_out_seq = true;

/* queue */
mutex_lock(&con->mutex);
BUG_ON(!list_empty(&msg->list_head));
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1 change: 1 addition & 0 deletions fs/ceph/messenger.h
Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,7 @@ struct ceph_msg {
struct kref kref;
bool front_is_vmalloc;
bool more_to_follow;
bool needs_out_seq;
int front_max;

struct ceph_msgpool *pool;
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