pstore/ram_core: Factor persistent_ram_zap() out of post_init()

A handy function that we will use outside of ram_core soon. But
so far just factor it out and start using it in post_init().
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/pstore/ram_core.c

@@ -320,6 +320,13 @@ void persistent_ram_free_old(struct persistent_ram_zone *prz)
 	prz->old_log_size = 0;
 }
 
+void persistent_ram_zap(struct persistent_ram_zone *prz)
+{
+	atomic_set(&prz->buffer->start, 0);
+	atomic_set(&prz->buffer->size, 0);
+	persistent_ram_update_header_ecc(prz);
+}
+
 static void *persistent_ram_vmap(phys_addr_t start, size_t size)
 {
 	struct page **pages;
@@ -414,8 +421,7 @@ static int __init persistent_ram_post_init(struct persistent_ram_zone *prz, bool
 	}
 
 	prz->buffer->sig = PERSISTENT_RAM_SIG;
-	atomic_set(&prz->buffer->start, 0);
-	atomic_set(&prz->buffer->size, 0);
+	persistent_ram_zap(prz);
 
 	return 0;
 }
@@ -450,7 +456,6 @@ struct persistent_ram_zone * __init persistent_ram_new(phys_addr_t start,
 		goto err;
 
 	persistent_ram_post_init(prz, ecc);
-	persistent_ram_update_header_ecc(prz);
 
 	return prz;
 err:

include/linux/pstore_ram.h

@@ -69,6 +69,7 @@ struct persistent_ram_zone * __init persistent_ram_new(phys_addr_t start,
 						       size_t size,
 						       bool ecc);
 void persistent_ram_free(struct persistent_ram_zone *prz);
+void persistent_ram_zap(struct persistent_ram_zone *prz);
 struct persistent_ram_zone *persistent_ram_init_ringbuffer(struct device *dev,
 		bool ecc);