Initialize the /dev/splatctl device buffer

On open() and initialize the buffer with the SPL version string.  The
user space splat utility expects to find the SPL version string when
it opens and reads from /dev/splatctl.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

module/spl/spl-generic.c

@@ -47,6 +47,7 @@
 #define DEBUG_SUBSYSTEM S_GENERIC
 
 char spl_version[16] = "SPL v" SPL_META_VERSION;
+EXPORT_SYMBOL(spl_version);
 
 long spl_hostid = 0;
 EXPORT_SYMBOL(spl_hostid);

module/splat/splat-ctl.c

@@ -70,10 +70,13 @@ splat_open(struct inode *inode, struct file *file)
 		kfree(info);
 		return -ENOMEM;
 	}
+	memset(info->info_buffer, 0, info->info_size);
 
 	info->info_head = info->info_buffer;
 	file->private_data = (void *)info;
 
+	splat_print(file, "%s\n", spl_version);
+
 	return 0;
 }