libceph: handle new osdmap down/state change encoding

Old incrementals encode a 0 value (nearly always) when an osd goes down.
Change that to allow any state bit(s) to be flipped.  Special case 0 to
mean flip the CEPH_OSD_UP bit to mimic the old behavior.
Signed-off-by: Sage Weil <sage@newdream.net>

net/ceph/osdmap.c

@@ -830,15 +830,20 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 		map->osd_addr[osd] = addr;
 	}
 
-	/* new_down */
+	/* new_state */
 	ceph_decode_32_safe(p, end, len, bad);
 	while (len--) {
 		u32 osd;
+		u8 xorstate;
 		ceph_decode_32_safe(p, end, osd, bad);
+		xorstate = **(u8 **)p;
 		(*p)++;  /* clean flag */
-		pr_info("osd%d down\n", osd);
+		if (xorstate == 0)
+			xorstate = CEPH_OSD_UP;
+		if (xorstate & CEPH_OSD_UP)
+			pr_info("osd%d down\n", osd);
 		if (osd < map->max_osd)
-			map->osd_state[osd] &= ~CEPH_OSD_UP;
+			map->osd_state[osd] ^= xorstate;
 	}
 
 	/* new_weight */