From 546a5d6122faae161cb59159e8af8518130efeab Mon Sep 17 00:00:00 2001 From: Xiubo Li Date: Wed, 30 Mar 2022 14:39:33 +0800 Subject: [PATCH] ceph: stop retrying the request when exceeding 256 times The type of 'r_attempts' in kernel 'ceph_mds_request' is 'int', while in 'ceph_mds_request_head' the type of 'num_retry' is '__u8'. So in case the request retries exceeding 256 times, the MDS will receive a incorrect retry seq. In this case it's ususally a bug in MDS and continue retrying the request makes no sense. For now let's limit it to 256. In future this could be fixed in ceph code, so avoid using the hardcode here. Signed-off-by: Xiubo Li Reviewed-by: Jeff Layton Signed-off-by: Ilya Dryomov --- fs/ceph/mds_client.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-) diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 75506ac30307..b5139382cf9b 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -2651,7 +2651,28 @@ static int __prepare_send_request(struct ceph_mds_session *session, struct ceph_mds_client *mdsc = session->s_mdsc; struct ceph_mds_request_head_old *rhead; struct ceph_msg *msg; - int flags = 0; + int flags = 0, max_retry; + + /* + * The type of 'r_attempts' in kernel 'ceph_mds_request' + * is 'int', while in 'ceph_mds_request_head' the type of + * 'num_retry' is '__u8'. So in case the request retries + * exceeding 256 times, the MDS will receive a incorrect + * retry seq. + * + * In this case it's ususally a bug in MDS and continue + * retrying the request makes no sense. + * + * In future this could be fixed in ceph code, so avoid + * using the hardcode here. + */ + max_retry = sizeof_field(struct ceph_mds_request_head, num_retry); + max_retry = 1 << (max_retry * BITS_PER_BYTE); + if (req->r_attempts >= max_retry) { + pr_warn_ratelimited("%s request tid %llu seq overflow\n", + __func__, req->r_tid); + return -EMULTIHOP; + } req->r_attempts++; if (req->r_inode) { @@ -2663,7 +2684,7 @@ static int __prepare_send_request(struct ceph_mds_session *session, else req->r_sent_on_mseq = -1; } - dout("prepare_send_request %p tid %lld %s (attempt %d)\n", req, + dout("%s %p tid %lld %s (attempt %d)\n", __func__, req, req->r_tid, ceph_mds_op_name(req->r_op), req->r_attempts); if (test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags)) {