From 5ffff11f1795f21a7fa923aa7534ad1d9f787004 Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@newdream.net>
Date: Fri, 21 Nov 2008 09:49:18 -0800
Subject: [PATCH] crush: introduce crush magic

This is a disk format change.
---
 src/crush/CrushWrapper.h | 9 +++++++++
 src/crush/crush.h        | 3 +++
 src/kernel/osdmap.c      | 9 ++++++++-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/crush/CrushWrapper.h b/src/crush/CrushWrapper.h
index 27ae7a60e30bc..d8aeffd67b5c3 100644
--- a/src/crush/CrushWrapper.h
+++ b/src/crush/CrushWrapper.h
@@ -352,6 +352,10 @@ public:
 
   void encode(bufferlist &bl, bool lean=false) {
     if (!crush) create();  // duh.
+
+    __u32 magic = CRUSH_MAGIC;
+    ::encode(magic, bl);
+
     ::encode(crush->max_buckets, bl);
     ::encode(crush->max_rules, bl);
     ::encode(crush->max_devices, bl);
@@ -419,6 +423,11 @@ public:
 
   void decode(bufferlist::iterator &blp) {
     create();
+
+    __u32 magic;
+    ::decode(magic, blp);
+    assert(magic == CRUSH_MAGIC);
+
     ::decode(crush->max_buckets, blp);
     ::decode(crush->max_rules, blp);
     ::decode(crush->max_devices, blp);
diff --git a/src/crush/crush.h b/src/crush/crush.h
index f7aab5ecf312d..e25976b17f609 100644
--- a/src/crush/crush.h
+++ b/src/crush/crush.h
@@ -17,6 +17,9 @@
  */
 
 
+#define CRUSH_MAGIC 0x00010000ul
+
+
 #define CRUSH_MAX_DEPTH 10
 #define CRUSH_MAX_SET   10
 
diff --git a/src/kernel/osdmap.c b/src/kernel/osdmap.c
index e61f4ce28f470..eae740633b55a 100644
--- a/src/kernel/osdmap.c
+++ b/src/kernel/osdmap.c
@@ -118,6 +118,7 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
 	int i, j;
 	void **p = &pbyval;
 	void *start = pbyval;
+	u32 magic;
 
 	dout(30, "crush_decode %p to %p len %d\n", *p, end, (int)(end - *p));
 
@@ -125,7 +126,13 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
 	if (c == NULL)
 		return ERR_PTR(-ENOMEM);
 
-	ceph_decode_need(p, end, 3*sizeof(u32), bad);
+	ceph_decode_need(p, end, 4*sizeof(u32), bad);
+	ceph_decode_32(p, magic);
+	if (magic != CRUSH_MAGIC) {
+		derr(0, "crush_decode magic %x != current %x\n",
+		     (unsigned)magic, (unsigned)CRUSH_MAGIC);
+		goto bad;
+	}
 	ceph_decode_32(p, c->max_buckets);
 	ceph_decode_32(p, c->max_rules);
 	ceph_decode_32(p, c->max_devices);
-- 
2.39.5