Merge tag 'ceph-for-4.14-rc2' of git://github.com/ceph/ceph-client

Pull ceph fixes from Ilya Dryomov:
 "Two small but important fixes: RADOS semantic change in upcoming v12.2.1
  release and a rare NULL dereference in create_session_open_msg()"

* tag 'ceph-for-4.14-rc2' of git://github.com/ceph/ceph-client:
  ceph: avoid panic in create_session_open_msg() if utsname() returns NULL
  libceph: don't allow bidirectional swap of pg-upmap-items

fs/ceph/mds_client.c

@@ -7,7 +7,6 @@
 #include <linux/sched.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
-#include <linux/utsname.h>
 #include <linux/ratelimit.h>
 
 #include "super.h"
@@ -884,8 +883,8 @@ static struct ceph_msg *create_session_open_msg(struct ceph_mds_client *mdsc, u6
 	void *p;
 
 	const char* metadata[][2] = {
-		{"hostname", utsname()->nodename},
-		{"kernel_version", utsname()->release},
+		{"hostname", mdsc->nodename},
+		{"kernel_version", init_utsname()->release},
 		{"entity_id", opt->name ? : ""},
 		{"root", fsopt->server_path ? : "/"},
 		{NULL, NULL}
@@ -3539,6 +3538,8 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc)
 	init_rwsem(&mdsc->pool_perm_rwsem);
 	mdsc->pool_perm_tree = RB_ROOT;
 
+	strncpy(mdsc->nodename, utsname()->nodename,
+		sizeof(mdsc->nodename) - 1);
 	return 0;
 }
 

fs/ceph/mds_client.h

@@ -8,6 +8,7 @@
 #include <linux/rbtree.h>
 #include <linux/spinlock.h>
 #include <linux/refcount.h>
+#include <linux/utsname.h>
 
 #include <linux/ceph/types.h>
 #include <linux/ceph/messenger.h>
@@ -368,6 +369,8 @@ struct ceph_mds_client {
 
 	struct rw_semaphore     pool_perm_rwsem;
 	struct rb_root		pool_perm_tree;
+
+	char nodename[__NEW_UTS_LEN + 1];
 };
 
 extern const char *ceph_mds_op_name(int op);

net/ceph/osdmap.c

@@ -2445,19 +2445,34 @@ static void apply_upmap(struct ceph_osdmap *osdmap,
 
 	pg = lookup_pg_mapping(&osdmap->pg_upmap_items, pgid);
 	if (pg) {
-		for (i = 0; i < raw->size; i++) {
-			for (j = 0; j < pg->pg_upmap_items.len; j++) {
-				int from = pg->pg_upmap_items.from_to[j][0];
-				int to = pg->pg_upmap_items.from_to[j][1];
-
-				if (from == raw->osds[i]) {
-					if (!(to != CRUSH_ITEM_NONE &&
-					      to < osdmap->max_osd &&
-					      osdmap->osd_weight[to] == 0))
-						raw->osds[i] = to;
+		/*
+		 * Note: this approach does not allow a bidirectional swap,
+		 * e.g., [[1,2],[2,1]] applied to [0,1,2] -> [0,2,1].
+		 */
+		for (i = 0; i < pg->pg_upmap_items.len; i++) {
+			int from = pg->pg_upmap_items.from_to[i][0];
+			int to = pg->pg_upmap_items.from_to[i][1];
+			int pos = -1;
+			bool exists = false;
+
+			/* make sure replacement doesn't already appear */
+			for (j = 0; j < raw->size; j++) {
+				int osd = raw->osds[j];
+
+				if (osd == to) {
+					exists = true;
 					break;
 				}
+				/* ignore mapping if target is marked out */
+				if (osd == from && pos < 0 &&
+				    !(to != CRUSH_ITEM_NONE &&
+				      to < osdmap->max_osd &&
+				      osdmap->osd_weight[to] == 0)) {
+					pos = j;
+				}
 			}
+			if (!exists && pos >= 0)
+				raw->osds[pos] = to;
 		}
 	}
 }