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

James Simmons jsimmons at infradead.org
Mon Nov 5 11:56:30 PST 2018


> 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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