Re: Data corruption when using multiple devices with NVMEoF TCP

[Sagi Grimberg <sagi@grimberg.me>]

Hey Hao,

> Here is the entire log (and it's a new one, i.e. above snippet not 
> included):
> https://drive.google.com/file/d/16ArIs5-Jw4P2f17A_ftKLm1A4LQUFpmg/view?usp=sharing
> 
> What I found is the data corruption does not always happen, especially 
> when I copy a small directory. So I guess a lot of log entries should 
> just look fine.

So this seems to be a breakage that existed for some time now with
multipage bvecs that you have been the first one to report. This
seems to be related to bio merges, which is seems strange to me
why this just now comes up, perhaps it is the combination with
raid0 that triggers this, I'm not sure.

IIUC, this should resolve your issue, care to give it a go?
--
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 973d5d683180..6bceadc204a8 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -201,8 +201,9 @@ static inline size_t nvme_tcp_req_cur_offset(struct 
nvme_tcp_request *req)

  static inline size_t nvme_tcp_req_cur_length(struct nvme_tcp_request *req)
  {
-       return min_t(size_t, req->iter.bvec->bv_len - req->iter.iov_offset,
-                       req->pdu_len - req->pdu_sent);
+       return min_t(size_t, req->iter.count,
+                       min_t(size_t, req->iter.bvec->bv_len - 
req->iter.iov_offset,
+                               req->pdu_len - req->pdu_sent));
  }

  static inline size_t nvme_tcp_pdu_data_left(struct nvme_tcp_request *req)
@@ -223,7 +224,7 @@ static void nvme_tcp_init_iter(struct 
nvme_tcp_request *req,
         struct request *rq = blk_mq_rq_from_pdu(req);
         struct bio_vec *vec;
         unsigned int size;
-       int nsegs;
+       int nsegs = 0;
         size_t offset;

         if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) {
@@ -233,11 +234,15 @@ static void nvme_tcp_init_iter(struct 
nvme_tcp_request *req,
                 offset = 0;
         } else {
                 struct bio *bio = req->curr_bio;
+               struct bvec_iter bi;
+               struct bio_vec bv;

                 vec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
-               nsegs = bio_segments(bio);
+               bio_for_each_bvec(bv, bio, bi) {
+                       nsegs++;
+               }
                 size = bio->bi_iter.bi_size;
-               offset = bio->bi_iter.bi_bvec_done;
+               offset = mp_bvec_iter_offset(bio->bi_io_vec, 
bio->bi_iter) - vec->bv_offset;
         }

         iov_iter_bvec(&req->iter, dir, vec, nsegs, size);
--

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