libceph: delete from need_resend_linger before check_linger_pool_dne()

When processing a map update consisting of multiple incrementals, we
may end up running check_linger_pool_dne() on a lingering request that
was previously added to need_resend_linger list.  If it is concluded
that the target pool doesn't exist, the request is killed off while
still on need_resend_linger list, which leads to a crash on a NULL
lreq->osd in kick_requests():

    libceph: linger_id 18446462598732840961 pool does not exist
    BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
    IP: ceph_osdc_handle_map+0x4ae/0x870

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 518dbac599d0400408646706c0a801a1ea573671..576101b635ef71ded2810985e962c464b31285e1 100644 (file)
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -3243,6 +3243,7 @@ static void scan_requests(struct ceph_osd *osd,
                                list_add_tail(&lreq->scan_item, need_resend_linger);
                        break;
                case CALC_TARGET_POOL_DNE:
+                       list_del_init(&lreq->scan_item);
                        check_linger_pool_dne(lreq);
                        break;
                }