libceph: Reset sparse-read on fault

When a fault occurs, the connection is abandoned, reestablished, and any pending operations are retried. The OSD client tracks the progress of a sparse-read reply using a separate state machine, largely independent of the messenger's state.

If a connection is lost mid-payload or the sparse-read state machine returns an error, the sparse-read state is not reset. The OSD client will then interpret the beginning of a new reply as the continuation of the old one. If this makes the sparse-read machinery enter a failure state, it may never recover, producing loops like:

libceph: [0] got 0 extents
libceph: data len 142248331 != extent len 0
libceph: osd0 (1)...:6801 socket error on read
libceph: data len 142248331 != extent len 0
libceph: osd0 (1)...:6801 socket error on read

Therefore, reset the sparse-read state in osd_fault(), ensuring retries start from a clean state.

Cc [email protected]

Signed-off-by Sam Edwards <[email protected]>

---
 net/ceph/osd_client.c | 3 +++
 1 file changed, 3 insertions(+)

net/ceph/osd_client.c +3 -1

index 3667319b949d..1a7be2f615dc 100644
@@ -4281,6 +4281,9 @@ static void osd_fault(struct ceph_connection *con)
                goto out_unlock;
        }
 
+       osd->o_sparse_op_idx = -1;
+       ceph_init_sparse_read(&osd->o_sparse_read);
+
        if (!reopen_osd(osd))
                kick_osd_requests(osd);
        maybe_request_map(osdc);
--

2.51.2