From 3dadb79e37487bca8b56ac06bc7726ec9b602de1 Mon Sep 17 00:00:00 2001
From: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Date: Wed, 15 Jan 2020 04:32:34 -0500
Subject: [PATCH] lib/blob: add EXTENT_RLE descriptor description

Since further patches will be adding new descriptors
that are related to cluster layout throughout the blobstore,
add description for existing descriptor too.

Signed-off-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Change-Id: I722eb633445685789d5185ed59dfc910f76b109f
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/481724
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Paul Luse <paul.e.luse@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
---
 lib/blob/blobstore.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/blob/blobstore.h b/lib/blob/blobstore.h
index 83f810634..8d7e8f3d4 100644
--- a/lib/blob/blobstore.h
+++ b/lib/blob/blobstore.h
@@ -245,11 +245,18 @@ struct spdk_bs_md_mask {
 };
 
 #define SPDK_MD_DESCRIPTOR_TYPE_PADDING 0
-#define SPDK_MD_DESCRIPTOR_TYPE_EXTENT_RLE 1
 #define SPDK_MD_DESCRIPTOR_TYPE_XATTR 2
 #define SPDK_MD_DESCRIPTOR_TYPE_FLAGS 3
 #define SPDK_MD_DESCRIPTOR_TYPE_XATTR_INTERNAL 4
 
+/* Following descriptors define cluster layout in a blob. */
+
+/* EXTENT_RLE descriptor holds an array of LBA that points to
+ * beginning of allocated clusters. The array is run-length encoded,
+ * with 0's being unallocated clusters. It is part of serialized
+ * metadata chain for a blob. */
+#define SPDK_MD_DESCRIPTOR_TYPE_EXTENT_RLE 1
+
 struct spdk_blob_md_descriptor_xattr {
 	uint8_t		type;
 	uint32_t	length;