[PATCH] nbd: Check magic before doing anything else

[Michal Feix <michal@feix.cz>]

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We should check magic sequence in reply packet before trying to find
request with it's request handle. This also solves the problem with
"Unexpected reply" message beeing logged, when packet with invalid magic
is received.

Signed-off-by: Michal Feix <michal@feix.cz>

---


[-- Attachment #2: nbd.c.magic-check.diff --]
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diff -upr 2.6.18-rc2.orig/drivers/block/nbd.c 2.6.18-rc2/drivers/block/nbd.c
--- 2.6.18-rc2.orig/drivers/block/nbd.c	2006-07-16 14:34:09.106878500 +0200
+++ 2.6.18-rc2/drivers/block/nbd.c	2006-07-16 14:48:59.000000000 +0200
@@ -300,6 +300,15 @@ static struct request *nbd_read_stat(str
 				lo->disk->disk_name, result);
 		goto harderror;
 	}
+
+	if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
+		printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
+				lo->disk->disk_name,
+				(unsigned long)ntohl(reply.magic));
+		result = -EPROTO;
+		goto harderror;
+	}
+
 	req = nbd_find_request(lo, reply.handle);
 	if (unlikely(IS_ERR(req))) {
 		result = PTR_ERR(req);
@@ -312,13 +321,6 @@ static struct request *nbd_read_stat(str
 		goto harderror;
 	}
 
-	if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
-		printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
-				lo->disk->disk_name,
-				(unsigned long)ntohl(reply.magic));
-		result = -EPROTO;
-		goto harderror;
-	}
 	if (ntohl(reply.error)) {
 		printk(KERN_ERR "%s: Other side returned error (%d)\n",
 				lo->disk->disk_name, ntohl(reply.error));