[lustre-devel] [PATCH 09/24] lustre: lnet: refactor lnet_del_peer_ni()

[NeilBrown <neilb@suse.com>]

From: Olaf Weber <olaf@sgi.com>

Refactor lnet_del_peer_ni(). In particular break out the code
that removes an lnet_peer_ni from an lnet_peer and put it into
a separate function, lnet_peer_del_nid().

WC-bug-id: https://jira.whamcloud.com/browse/LU-9480
Signed-off-by: Olaf Weber <olaf@sgi.com>
Reviewed-on: https://review.whamcloud.com/25779
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Tested-by: Amir Shehata <amir.shehata@intel.com>
Signed-off-by: NeilBrown <neilb@suse.com>
---
 drivers/staging/lustre/lnet/lnet/peer.c |   96 +++++++++++++++++++++++--------
 1 file changed, 71 insertions(+), 25 deletions(-)

diff --git a/drivers/staging/lustre/lnet/lnet/peer.c b/drivers/staging/lustre/lnet/lnet/peer.c
index bbf07008dbb0..30a2486712e4 100644
--- a/drivers/staging/lustre/lnet/lnet/peer.c
+++ b/drivers/staging/lustre/lnet/lnet/peer.c
@@ -254,7 +254,7 @@ lnet_peer_ni_del_locked(struct lnet_peer_ni *lpni)
 	 *
 	 * The last reference may be lost in a place where the
 	 * lnet_net_lock locks only a single cpt, and that cpt may not
-	 * be lpni->lpni_cpt. So the zombie list of this peer_table
+	 * be lpni->lpni_cpt. So the zombie list of lnet_peer_table
 	 * has its own lock.
 	 */
 	spin_lock(&ptable->pt_zombie_lock);
@@ -340,6 +340,61 @@ lnet_peer_del_locked(struct lnet_peer *peer)
 	return rc2;
 }
 
+static int
+lnet_peer_del(struct lnet_peer *peer)
+{
+	lnet_net_lock(LNET_LOCK_EX);
+	lnet_peer_del_locked(peer);
+	lnet_net_unlock(LNET_LOCK_EX);
+
+	return 0;
+}
+
+/*
+ * Delete a NID from a peer.
+ * Implements a few sanity checks.
+ * Call with ln_api_mutex held.
+ */
+static int
+lnet_peer_del_nid(struct lnet_peer *lp, lnet_nid_t nid)
+{
+	struct lnet_peer *lp2;
+	struct lnet_peer_ni *lpni;
+
+	lpni = lnet_find_peer_ni_locked(nid);
+	if (!lpni) {
+		CERROR("Cannot remove unknown nid %s from peer %s\n",
+		       libcfs_nid2str(nid),
+		       libcfs_nid2str(lp->lp_primary_nid));
+		return -ENOENT;
+	}
+	lnet_peer_ni_decref_locked(lpni);
+	lp2 = lpni->lpni_peer_net->lpn_peer;
+	if (lp2 != lp) {
+		CERROR("Nid %s is attached to peer %s, not peer %s\n",
+		       libcfs_nid2str(nid),
+		       libcfs_nid2str(lp2->lp_primary_nid),
+		       libcfs_nid2str(lp->lp_primary_nid));
+		return -EINVAL;
+	}
+
+	/*
+	 * This function only allows deletion of the primary NID if it
+	 * is the only NID.
+	 */
+	if (nid == lp->lp_primary_nid && lnet_get_num_peer_nis(lp) != 1) {
+		CERROR("Cannot delete primary NID %s from multi-NID peer\n",
+		       libcfs_nid2str(nid));
+		return -EINVAL;
+	}
+
+	lnet_net_lock(LNET_LOCK_EX);
+	lnet_peer_ni_del_locked(lpni);
+	lnet_net_unlock(LNET_LOCK_EX);
+
+	return 0;
+}
+
 static void
 lnet_peer_table_cleanup_locked(struct lnet_net *net,
 			       struct lnet_peer_table *ptable)
@@ -938,45 +993,36 @@ lnet_add_peer_ni(lnet_nid_t prim_nid, lnet_nid_t nid, bool mr)
  *   Delete a NI from a peer if both prim_nid and nid are provided.
  *   Delete a peer if only prim_nid is provided.
  *   Delete a peer if its primary nid is provided.
+ *
+ * The caller must hold ln_api_mutex. This prevents the peer from
+ * being modified/deleted by a different thread.
  */
 int
 lnet_del_peer_ni(lnet_nid_t prim_nid, lnet_nid_t nid)
 {
-	lnet_nid_t local_nid;
-	struct lnet_peer *peer;
+	struct lnet_peer *lp;
 	struct lnet_peer_ni *lpni;
-	int rc;
 
 	if (prim_nid == LNET_NID_ANY)
 		return -EINVAL;
 
-	local_nid = (nid != LNET_NID_ANY) ? nid : prim_nid;
-
-	lpni = lnet_find_peer_ni_locked(local_nid);
+	lpni = lnet_find_peer_ni_locked(prim_nid);
 	if (!lpni)
-		return -EINVAL;
+		return -ENOENT;
 	lnet_peer_ni_decref_locked(lpni);
+	lp = lpni->lpni_peer_net->lpn_peer;
 
-	peer = lpni->lpni_peer_net->lpn_peer;
-	LASSERT(peer);
-
-	if (peer->lp_primary_nid == lpni->lpni_nid) {
-		/*
-		 * deleting the primary ni is equivalent to deleting the
-		 * entire peer
-		 */
-		lnet_net_lock(LNET_LOCK_EX);
-		rc = lnet_peer_del_locked(peer);
-		lnet_net_unlock(LNET_LOCK_EX);
-
-		return rc;
+	if (prim_nid != lp->lp_primary_nid) {
+		CDEBUG(D_NET, "prim_nid %s is not primary for peer %s\n",
+		       libcfs_nid2str(prim_nid),
+		       libcfs_nid2str(lp->lp_primary_nid));
+		return -ENODEV;
 	}
 
-	lnet_net_lock(LNET_LOCK_EX);
-	rc = lnet_peer_ni_del_locked(lpni);
-	lnet_net_unlock(LNET_LOCK_EX);
+	if (nid == LNET_NID_ANY || nid == lp->lp_primary_nid)
+		return lnet_peer_del(lp);
 
-	return rc;
+	return lnet_peer_del_nid(lp, nid);
 }
 
 void