[lustre-devel] [PATCH] lustre: remove iter type from iov_iter_[b|k]vec()

Andreas Dilger adilger at whamcloud.com
Mon Nov 5 18:06:18 PST 2018


The WARN_ON() should probably be changed to WARN_ON_ONCE()?

Cheers, Andreas

> On Nov 5, 2018, at 13:12, James Simmons <jsimmons at infradead.org> wrote:
> 
> 
>>> On Nov 5, 2018, at 11:18, James Simmons <jsimmons at infradead.org> wrote:
>>> 
>>> The linux commit aa563d7bca6e ("iov_iter: Separate type from
>>> direction and use accessor functions) removed the iter type
>>> from both iov_iter_bvec() and iov_iter_kvec(). Update lustre
>>> to this change. Without it we see in testing:
>>> 
>>> WARNING: CPU: 2 PID: 3088 at lib/iov_iter.c:1082 iov_iter_kvec+0x25/0x30
>> 
>> I'm no LNet expert, but it would seem that just removing the ITER_KVEC
>> flag would cause problems with the code?  As recently as the 4.17 kernel
>> it looks like removing this flag would cause a BUG_ON():
>> 
>> void iov_iter_kvec(struct iov_iter *i, int direction,
>>                        const struct kvec *kvec, unsigned long nr_segs,
>>                        size_t count)
>> {
>>        BUG_ON(!(direction & ITER_KVEC));
>>        i->type = direction;
>>        i->kvec = kvec;
>>        i->nr_segs = nr_segs;
>>        i->iov_offset = 0;
>>        i->count = count;
>> }
>> 
>> I suspect what you need to do is something like:
>> 
>> #if <something>
>> #define LNET_ITER_KVEC 0
>> #else
>> #define LNET_ITER_KVEC ITER_KVEC
>> #endif
>> 
>> so that it works on both old and new kernels, at least for the version
>> that is included in the master repo.
>> 
>> Cheers, Andreas
> 
> For the OpenSFS branch yes we will have to do something like that to 
> support various kernel releases. The change was just landed in the 
> 4.20-rc1 cycle. iov_iter_kvec is now:
> 
> void iov_iter_kvec(struct iov_iter *i, unsigned int direction,
>                        const struct kvec *kvec, unsigned long nr_segs,
>                        size_t count)
> {
>        WARN_ON(direction & ~(READ | WRITE));
>        i->type = ITER_KVEC | (direction & (READ | WRITE));
>        i->kvec = kvec;
>        i->nr_segs = nr_segs;
>        i->iov_offset = 0;
>        i->count = count;
> }
> EXPORT_SYMBOL(iov_iter_kvec);
> 
> With LNet the WARN_ON was causing so many back traces to appear that it 
> cause my testing to grind to a halt :-( 
> 
>>> Signed-off-by: James Simmons <jsimmons at infradead.org>
>>> ---
>>> drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c  | 4 ++--
>>> drivers/staging/lustre/lnet/klnds/socklnd/socklnd_cb.c  | 8 ++++----
>>> drivers/staging/lustre/lnet/klnds/socklnd/socklnd_lib.c | 4 ++--
>>> drivers/staging/lustre/lnet/lnet/lib-move.c             | 4 ++--
>>> drivers/staging/lustre/lnet/lnet/lib-socket.c           | 4 ++--
>>> 5 files changed, 12 insertions(+), 12 deletions(-)
>>> 
>>> diff --git a/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c b/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
>>> index 23ce59e..57fe037 100644
>>> --- a/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
>>> +++ b/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
>>> @@ -1548,11 +1548,11 @@ static int kiblnd_resolve_addr(struct rdma_cm_id *cmid,
>>>    LASSERT(!(payload_kiov && payload_iov));
>>> 
>>>    if (payload_kiov)
>>> -        iov_iter_bvec(&from, ITER_BVEC | WRITE,
>>> +        iov_iter_bvec(&from, WRITE,
>>>                  payload_kiov, payload_niov,
>>>                  payload_nob + payload_offset);
>>>    else
>>> -        iov_iter_kvec(&from, ITER_KVEC | WRITE,
>>> +        iov_iter_kvec(&from, WRITE,
>>>                  payload_iov, payload_niov,
>>>                  payload_nob + payload_offset);
>>> 
>>> diff --git a/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_cb.c b/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_cb.c
>>> index c401896..4abf0eb 100644
>>> --- a/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_cb.c
>>> +++ b/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_cb.c
>>> @@ -1001,7 +1001,7 @@ struct ksock_route *
>>>            kvec->iov_base = &conn->ksnc_msg;
>>>            kvec->iov_len = offsetof(struct ksock_msg, ksm_u);
>>>            conn->ksnc_rx_nob_left = offsetof(struct ksock_msg, ksm_u);
>>> -            iov_iter_kvec(&conn->ksnc_rx_to, READ|ITER_KVEC, kvec,
>>> +            iov_iter_kvec(&conn->ksnc_rx_to, READ, kvec,
>>>                    1, offsetof(struct ksock_msg, ksm_u));
>>>            break;
>>> 
>>> @@ -1011,7 +1011,7 @@ struct ksock_route *
>>>            kvec->iov_base = &conn->ksnc_msg.ksm_u.lnetmsg;
>>>            kvec->iov_len = sizeof(struct lnet_hdr);
>>>            conn->ksnc_rx_nob_left = sizeof(struct lnet_hdr);
>>> -            iov_iter_kvec(&conn->ksnc_rx_to, READ|ITER_KVEC, kvec,
>>> +            iov_iter_kvec(&conn->ksnc_rx_to, READ, kvec,
>>>                    1, sizeof(struct lnet_hdr));
>>>            break;
>>> 
>>> @@ -1043,7 +1043,7 @@ struct ksock_route *
>>>    } while (nob_to_skip &&    /* mustn't overflow conn's rx iov */
>>>         niov < sizeof(conn->ksnc_rx_iov_space) / sizeof(struct iovec));
>>> 
>>> -    iov_iter_kvec(&conn->ksnc_rx_to, READ|ITER_KVEC, kvec, niov, skipped);
>>> +    iov_iter_kvec(&conn->ksnc_rx_to, READ, kvec, niov, skipped);
>>>    return 0;
>>> }
>>> 
>>> @@ -1157,7 +1157,7 @@ struct ksock_route *
>>>        kvec->iov_base = &conn->ksnc_msg.ksm_u.lnetmsg;
>>>        kvec->iov_len = sizeof(struct ksock_lnet_msg);
>>> 
>>> -        iov_iter_kvec(&conn->ksnc_rx_to, READ|ITER_KVEC, kvec,
>>> +        iov_iter_kvec(&conn->ksnc_rx_to, READ, kvec,
>>>                1, sizeof(struct ksock_lnet_msg));
>>> 
>>>        goto again;     /* read lnet header now */
>>> diff --git a/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_lib.c b/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_lib.c
>>> index 33847b9..686c2d3 100644
>>> --- a/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_lib.c
>>> +++ b/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_lib.c
>>> @@ -92,7 +92,7 @@
>>>        nob < tx->tx_resid)
>>>        msg.msg_flags |= MSG_MORE;
>>> 
>>> -    iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC,
>>> +    iov_iter_kvec(&msg.msg_iter, WRITE,
>>>              tx->tx_iov, tx->tx_niov, nob);
>>>    return sock_sendmsg(sock, &msg);
>>> }
>>> @@ -140,7 +140,7 @@
>>>            nob < tx->tx_resid)
>>>            msg.msg_flags |= MSG_MORE;
>>> 
>>> -        iov_iter_bvec(&msg.msg_iter, WRITE | ITER_BVEC,
>>> +        iov_iter_bvec(&msg.msg_iter, WRITE,
>>>                  kiov, tx->tx_nkiov, nob);
>>>        rc = sock_sendmsg(sock, &msg);
>>>    }
>>> diff --git a/drivers/staging/lustre/lnet/lnet/lib-move.c b/drivers/staging/lustre/lnet/lnet/lib-move.c
>>> index 5694d85..eaa1dfa 100644
>>> --- a/drivers/staging/lustre/lnet/lnet/lib-move.c
>>> +++ b/drivers/staging/lustre/lnet/lnet/lib-move.c
>>> @@ -498,10 +498,10 @@ void lnet_usr_translate_stats(struct lnet_ioctl_element_msg_stats *msg_stats,
>>>    }
>>> 
>>>    if (iov) {
>>> -        iov_iter_kvec(&to, ITER_KVEC | READ, iov, niov, mlen + offset);
>>> +        iov_iter_kvec(&to, READ, iov, niov, mlen + offset);
>>>        iov_iter_advance(&to, offset);
>>>    } else {
>>> -        iov_iter_bvec(&to, ITER_BVEC | READ, kiov, niov, mlen + offset);
>>> +        iov_iter_bvec(&to, READ, kiov, niov, mlen + offset);
>>>        iov_iter_advance(&to, offset);
>>>    }
>>>    rc = ni->ni_net->net_lnd->lnd_recv(ni, private, msg, delayed, &to, rlen);
>>> diff --git a/drivers/staging/lustre/lnet/lnet/lib-socket.c b/drivers/staging/lustre/lnet/lnet/lib-socket.c
>>> index d9c62d3..62a742e 100644
>>> --- a/drivers/staging/lustre/lnet/lnet/lib-socket.c
>>> +++ b/drivers/staging/lustre/lnet/lnet/lib-socket.c
>>> @@ -58,7 +58,7 @@
>>>     * Caller may pass a zero timeout if she thinks the socket buffer is
>>>     * empty enough to take the whole message immediately
>>>     */
>>> -    iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, &iov, 1, nob);
>>> +    iov_iter_kvec(&msg.msg_iter, WRITE, &iov, 1, nob);
>>>    for (;;) {
>>>        msg.msg_flags = !timeout ? MSG_DONTWAIT : 0;
>>>        if (timeout) {
>>> @@ -113,7 +113,7 @@
>>>    LASSERT(nob > 0);
>>>    LASSERT(jiffies_left > 0);
>>> 
>>> -    iov_iter_kvec(&msg.msg_iter, READ | ITER_KVEC, &iov, 1, nob);
>>> +    iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, nob);
>>> 
>>>    for (;;) {
>>>        /* Set receive timeout to remaining time */
>>> -- 
>>> 1.8.3.1
>>> 
>> 
>> Cheers, Andreas
>> ---
>> Andreas Dilger
>> CTO Whamcloud
>> 
>> 
>> 
>> 
>> 


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