blockjob: Improve BlockJobInfo.offset/len documentation

Clarify that len is just an estimation of the end value of offset, and
that offset increases monotonically while len can change arbitrarily.

While touching the documentation of offset, move it directly after len
to match the order of the declaration below.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>

diff --git a/qapi/block-core.json b/qapi/block-core.json
index d32ec95..0e29abf 100644 (file)
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1148,7 +1148,12 @@
 # @device: The job identifier. Originally the device name but other
 #          values are allowed since QEMU 2.7
 #
-# @len: the maximum progress value
+# @len: Estimated @offset value at the completion of the job. This value can
+#       arbitrarily change while the job is running, in both directions.
+#
+# @offset: Progress made until now. The unit is arbitrary and the value can
+#          only meaningfully be used for the ratio of @offset to @len. The
+#          value is monotonically increasing.
 #
 # @busy: false if the job is known to be in a quiescent state, with
 #        no pending I/O.  Since 1.3.
@@ -1156,8 +1161,6 @@
 # @paused: whether the job is paused or, if @busy is true, will
 #          pause itself as soon as possible.  Since 1.3.
 #
-# @offset: the current progress value
-#
 # @speed: the rate limit, bytes per second
 #
 # @io-status: the status of the job (since 1.3)