From e6918187568dbd01842d8d1d2c808ce16a894239 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sun, 21 Apr 2024 13:54:28 +0200
Subject: Adding upstream version 18.2.2.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 doc/dev/rbd-export.rst | 104 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 doc/dev/rbd-export.rst

(limited to 'doc/dev/rbd-export.rst')

diff --git a/doc/dev/rbd-export.rst b/doc/dev/rbd-export.rst
new file mode 100644
index 000000000..2edb637f6
--- /dev/null
+++ b/doc/dev/rbd-export.rst
@@ -0,0 +1,104 @@
+RBD Export & Import
+===================
+
+This is a file format of an RBD image or snapshot. It's a sparse format
+for the full image. There are three recording sections in the file.
+
+(1) Header.
+(2) Metadata.
+(3) Diffs.
+
+Header
+~~~~~~
+
+"rbd image v2\\n"
+
+Metadata records
+~~~~~~~~~~~~~~~~
+
+Every record has a one byte "tag" that identifies the record type,
+followed by length of data, and then some other data.
+
+Metadata records come in the first part of the image.  Order is not
+important, as long as all the metadata records come before the data
+records.
+
+In v2, we have the following metadata in each section:
+(1 Bytes) tag.
+(8 Bytes) length.
+(n Bytes) data.
+
+In this way, we can skip the unrecognized tag.
+
+Image order
+-----------
+
+- u8: 'O'
+- le64: length of appending data (8)
+- le64: image order
+
+Image format
+------------
+
+- u8: 'F'
+- le64: length of appending data (8)
+- le64: image format
+
+Image Features
+--------------
+
+- u8: 'T'
+- le64: length of appending data (8)
+- le64: image features
+
+Image Stripe unit
+-----------------
+
+- u8: 'U'
+- le64: length of appending data (8)
+- le64: image striping unit
+
+Image Stripe count
+------------------
+
+- u8: 'C'
+- le64: length of appending data (8)
+- le64: image striping count
+
+ImageMeta Key and Value
+-----------------------
+
+- u8: 'M'
+- le64: length of appending data (length of key + length of value + 4 * 2)
+- string: image-meta key
+- string: image-meta value
+
+Final Record
+~~~~~~~~~~~~
+
+End
+---
+
+- u8: 'E'
+
+
+Diffs records
+~~~~~~~~~~~~~
+
+Record the all snapshots and the HEAD in this section. 
+
+Snap Protection status
+----------------------
+
+Record the snapshot's protection status if `--export-format=2`.
+- u8: 'p'
+- le64: length of appending data (8)
+- u8: snap protection status (0 for false, 1 for true)
+
+Others
+------
+
+- le64: number of diffs
+- Diffs ...
+
+Detail please refer to rbd-diff.rst
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