libceph: allocate dummy osdmap in ceph_osdc_init()

This leads to a simpler osdmap handling code, particularly when dealing
with pi->was_full, which is introduced in a later commit.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

include/linux/ceph/osdmap.h

@@ -225,6 +225,7 @@ static inline int ceph_decode_pgid(void **p, void *end, struct ceph_pg *pgid)
 	return 0;
 }
 
+struct ceph_osdmap *ceph_osdmap_alloc(void);
 extern struct ceph_osdmap *ceph_osdmap_decode(void **p, void *end);
 struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 					     struct ceph_osdmap *map);

net/ceph/osd_client.c

@@ -2255,7 +2255,7 @@ void ceph_osdc_handle_map(struct ceph_osd_client *osdc, struct ceph_msg *msg)
 	struct ceph_fsid fsid;
 	bool was_full;
 
-	dout("handle_map have %u\n", osdc->osdmap ? osdc->osdmap->epoch : 0);
+	dout("handle_map have %u\n", osdc->osdmap->epoch);
 	p = msg->front.iov_base;
 	end = p + msg->front.iov_len;
 
@@ -2278,7 +2278,7 @@ void ceph_osdc_handle_map(struct ceph_osd_client *osdc, struct ceph_msg *msg)
 		maplen = ceph_decode_32(&p);
 		ceph_decode_need(&p, end, maplen, bad);
 		next = p + maplen;
-		if (osdc->osdmap && osdc->osdmap->epoch+1 == epoch) {
+		if (osdc->osdmap->epoch+1 == epoch) {
 			dout("applying incremental map %u len %d\n",
 			     epoch, maplen);
 			newmap = osdmap_apply_incremental(&p, next,
@@ -2317,7 +2317,7 @@ void ceph_osdc_handle_map(struct ceph_osd_client *osdc, struct ceph_msg *msg)
 		if (nr_maps > 1) {
 			dout("skipping non-latest full map %u len %d\n",
 			     epoch, maplen);
-		} else if (osdc->osdmap && osdc->osdmap->epoch >= epoch) {
+		} else if (osdc->osdmap->epoch >= epoch) {
 			dout("skipping full map %u len %d, "
 			     "older than our %u\n", epoch, maplen,
 			     osdc->osdmap->epoch);
@@ -2347,8 +2347,6 @@ void ceph_osdc_handle_map(struct ceph_osd_client *osdc, struct ceph_msg *msg)
 		nr_maps--;
 	}
 
-	if (!osdc->osdmap)
-		goto bad;
 done:
 	downgrade_write(&osdc->map_sem);
 	ceph_monc_got_map(&osdc->client->monc, CEPH_SUB_OSDMAP,
@@ -2690,7 +2688,6 @@ int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
 
 	dout("init\n");
 	osdc->client = client;
-	osdc->osdmap = NULL;
 	init_rwsem(&osdc->map_sem);
 	mutex_init(&osdc->request_mutex);
 	osdc->last_tid = 0;
@@ -2709,10 +2706,14 @@ int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
 	osdc->event_count = 0;
 
 	err = -ENOMEM;
+	osdc->osdmap = ceph_osdmap_alloc();
+	if (!osdc->osdmap)
+		goto out;
+
 	osdc->req_mempool = mempool_create_slab_pool(10,
 						     ceph_osd_request_cache);
 	if (!osdc->req_mempool)
-		goto out;
+		goto out_map;
 
 	err = ceph_msgpool_init(&osdc->msgpool_op, CEPH_MSG_OSD_OP,
 				PAGE_SIZE, 10, true, "osd_op");
@@ -2741,6 +2742,8 @@ int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
 	ceph_msgpool_destroy(&osdc->msgpool_op);
 out_mempool:
 	mempool_destroy(osdc->req_mempool);
+out_map:
+	ceph_osdmap_destroy(osdc->osdmap);
 out:
 	return err;
 }
@@ -2760,10 +2763,7 @@ void ceph_osdc_stop(struct ceph_osd_client *osdc)
 	}
 	mutex_unlock(&osdc->request_mutex);
 
-	if (osdc->osdmap) {
 	ceph_osdmap_destroy(osdc->osdmap);
-		osdc->osdmap = NULL;
-	}
 	mempool_destroy(osdc->req_mempool);
 	ceph_msgpool_destroy(&osdc->msgpool_op);
 	ceph_msgpool_destroy(&osdc->msgpool_op_reply);

net/ceph/osdmap.c

@@ -707,6 +707,23 @@ static int decode_pool_names(void **p, void *end, struct ceph_osdmap *map)
 /*
  * osd map
  */
+struct ceph_osdmap *ceph_osdmap_alloc(void)
+{
+	struct ceph_osdmap *map;
+
+	map = kzalloc(sizeof(*map), GFP_NOIO);
+	if (!map)
+		return NULL;
+
+	map->pg_pools = RB_ROOT;
+	map->pool_max = -1;
+	map->pg_temp = RB_ROOT;
+	map->primary_temp = RB_ROOT;
+	mutex_init(&map->crush_scratch_mutex);
+
+	return map;
+}
+
 void ceph_osdmap_destroy(struct ceph_osdmap *map)
 {
 	dout("osdmap_destroy %p\n", map);
@@ -1230,14 +1247,10 @@ struct ceph_osdmap *ceph_osdmap_decode(void **p, void *end)
 	struct ceph_osdmap *map;
 	int ret;
 
-	map = kzalloc(sizeof(*map), GFP_NOFS);
+	map = ceph_osdmap_alloc();
 	if (!map)
 		return ERR_PTR(-ENOMEM);
 
-	map->pg_temp = RB_ROOT;
-	map->primary_temp = RB_ROOT;
-	mutex_init(&map->crush_scratch_mutex);
-
 	ret = osdmap_decode(p, end, map);
 	if (ret) {
 		ceph_osdmap_destroy(map);