irmap: Don't let proc-parse free handle's mem before caching

Bug was introduced by on-disk-irmap-cache patch. The proc-parse
routine allocates memory for handle, calls ->cb then frees handle.

The problem is that the cb in case of pre-dump saves the handle
for future reference. So, in this future handle's mem happen to
be corrupted.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

irmap.c

@@ -271,6 +271,7 @@ int irmap_queue_cache(unsigned int dev, unsigned long ino,
 	ip->dev = dev;
 	ip->ino = ino;
 	ip->fh = *fh;
+	fh->handle = NULL; /* don't free in free_fhandle */
 
 	pr_debug("Queue %x:%lx for pre-dump\n", dev, ino);
 

proc_parse.c

@@ -854,7 +854,8 @@ static int alloc_fhandle(FhEntry *fh)
 
 static void free_fhandle(FhEntry *fh)
 {
-	xfree(fh->handle);
+	if (fh->handle)
+		xfree(fh->handle);
 }
 
 static void parse_fhandle_encoded(char *tok, FhEntry *fh)