[Qemu-devel] [PATCH v3 0/5] block: add optional 'speed' parameter to block-stream

[Stefan Hajnoczi]

Eric Blake raised concerns about the inability to start block jobs with a speed
limit.  Current the user needs to follow up the block-stream command with
block-job-set-speed.  There is a window of time while the new block job is
running but block-job-set-speed has not been processed yet.

This series adds an optional 'speed' parameter to block-stream so streaming can
be started with a speed limit that takes effect immediately.

For consistency it also renames the block-job-set-speed parameter from 'value'
to 'speed'.  This is externally visible, but this API has not been in a QEMU
release yet so we can still do this.

I considered several other approaches, including adding a
default_block_job_speed field to BlockDriverState but ultimately the cleanest
solution is to pass in a speed parameter on job creation.  This way we do not
change semantics of existing commands, we only add an optional parameter.  We
also do not need to add state to BlockDriverState, which is already huge and
messy.

v3:
 * Fix 'an' -> 'and' typo in Patch 1 description [Eric]
 * Document block-stream @speed parameter fully [Kevin]
 * Rephrase error argument doc comment [Luiz]
 * Fix block_stream [speed [base]] options doc [Eric]
 * Fix BlockJobSpeedInvalid -> InvalidParameter [Luiz]
 * Add test for block job speed setting success case [Eric]
 * Drop unrelated qemu-iotests 030 fix from this series

Stefan Hajnoczi (5):
  block: use Error mechanism instead of -errno for block_job_create()
  block: use Error mechanism instead of -errno for
    block_job_set_speed()
  block: change block-job-set-speed argument from 'value' to 'speed'
  block: add 'speed' optional parameter to block-stream
  qemu-iotests: add block-stream speed value test case

 block.c                    |   35 +++++++++++++----
 block/stream.c             |   22 +++++------
 block_int.h                |   19 ++++++---
 blockdev.c                 |   26 +++++--------
 hmp-commands.hx            |    8 ++--
 hmp.c                      |    4 +-
 qapi-schema.json           |   12 ++++--
 qmp-commands.hx            |    4 +-
 tests/qemu-iotests/030     |   91 ++++++++++++++++++++++++++++++++++----------
 tests/qemu-iotests/030.out |    4 +-
 10 files changed, 151 insertions(+), 74 deletions(-)

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1.7.10