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Re: [Qemu-block] [PATCH 1/2] The discard flag for block stream operation
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-block] [PATCH 1/2] The discard flag for block stream operation |
Date: |
Wed, 31 Oct 2018 17:38:34 +0000 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
* Andrey Shinkevich (address@hidden) wrote:
> Adding a parameter to QMP block-stream command to allow discarding
> blocks in the backing chain while blocks are being copied to the
> active layer.
>
> Signed-off-by: Andrey Shinkevich <address@hidden>
> ---
> block/stream.c | 2 +-
> blockdev.c | 8 +++++++-
> hmp-commands.hx | 4 ++--
> hmp.c | 4 +++-
> include/block/block_int.h | 2 +-
> qapi/block-core.json | 5 ++++-
> 6 files changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/block/stream.c b/block/stream.c
> index 81a7ec8..db81df4 100644
> --- a/block/stream.c
> +++ b/block/stream.c
> @@ -221,7 +221,7 @@ static const BlockJobDriver stream_job_driver = {
>
> void stream_start(const char *job_id, BlockDriverState *bs,
> BlockDriverState *base, const char *backing_file_str,
> - int creation_flags, int64_t speed,
> + int creation_flags, int64_t speed, bool discard,
> BlockdevOnError on_error, Error **errp)
> {
> StreamBlockJob *s;
> diff --git a/blockdev.c b/blockdev.c
> index 574adbc..04aecf5 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3122,6 +3122,7 @@ void qmp_block_stream(bool has_job_id, const char
> *job_id, const char *device,
> bool has_base_node, const char *base_node,
> bool has_backing_file, const char *backing_file,
> bool has_speed, int64_t speed,
> + bool has_discard, bool discard,
> bool has_on_error, BlockdevOnError on_error,
> bool has_auto_finalize, bool auto_finalize,
> bool has_auto_dismiss, bool auto_dismiss,
> @@ -3138,6 +3139,10 @@ void qmp_block_stream(bool has_job_id, const char
> *job_id, const char *device,
> on_error = BLOCKDEV_ON_ERROR_REPORT;
> }
>
> + if (!has_discard) {
> + discard = false;
> + }
> +
> bs = bdrv_lookup_bs(device, device, errp);
> if (!bs) {
> return;
> @@ -3202,7 +3207,8 @@ void qmp_block_stream(bool has_job_id, const char
> *job_id, const char *device,
> }
>
> stream_start(has_job_id ? job_id : NULL, bs, base_bs, base_name,
> - job_flags, has_speed ? speed : 0, on_error, &local_err);
> + job_flags, has_speed ? speed : 0,
> + discard, on_error, &local_err);
> if (local_err) {
> error_propagate(errp, local_err);
> goto out;
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index db0c681..b455e0d 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -95,8 +95,8 @@ ETEXI
>
> {
> .name = "block_stream",
> - .args_type = "device:B,speed:o?,base:s?",
> - .params = "device [speed [base]]",
> + .args_type = "device:B,speed:o?,base:s?,discard:o?",
I think that 'o?' is wrong - see the table at the top of monitor.c, 'o'
is octets, ? is optional - so speed here is an optional byte count, I
think your 'discard' is just an optional flag.
So I think you'd be better with a flag, like the -f on block_job_cancel.
> + .params = "device [speed [base]] [discard]",
> .help = "copy data from a backing file into a block device",
> .cmd = hmp_block_stream,
> },
> diff --git a/hmp.c b/hmp.c
> index 7828f93..c63e806 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -1920,9 +1920,11 @@ void hmp_block_stream(Monitor *mon, const QDict *qdict)
> const char *device = qdict_get_str(qdict, "device");
> const char *base = qdict_get_try_str(qdict, "base");
> int64_t speed = qdict_get_try_int(qdict, "speed", 0);
> + bool discard = qdict_get_try_bool(qdict, "discard", false);
>
> qmp_block_stream(true, device, device, base != NULL, base, false, NULL,
> - false, NULL, qdict_haskey(qdict, "speed"), speed, true,
> + false, NULL, qdict_haskey(qdict, "speed"), speed,
> + qdict_haskey(qdict, "discard"), discard, true,
Since you've got the default 'false' on the bool discard = above, I
wonder if that can just be true, discard, true ?
Dave
> BLOCKDEV_ON_ERROR_REPORT, false, false, false, false,
> &error);
>
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 92ecbd8..e531d03 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -970,7 +970,7 @@ int is_windows_drive(const char *filename);
> */
> void stream_start(const char *job_id, BlockDriverState *bs,
> BlockDriverState *base, const char *backing_file_str,
> - int creation_flags, int64_t speed,
> + int creation_flags, int64_t speed, bool discard,
> BlockdevOnError on_error, Error **errp);
>
> /**
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index cfb37f8..3f50b88 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -2329,6 +2329,9 @@
> #
> # @speed: the maximum speed, in bytes per second
> #
> +# @discard: true to delete blocks duplicated in old backing files.
> +# (default: false). Since 3.1.
> +#
> # @on-error: the action to take on an error (default report).
> # 'stop' and 'enospc' can only be used if the block device
> # supports io-status (see BlockInfo). Since 1.3.
> @@ -2361,7 +2364,7 @@
> { 'command': 'block-stream',
> 'data': { '*job-id': 'str', 'device': 'str', '*base': 'str',
> '*base-node': 'str', '*backing-file': 'str', '*speed': 'int',
> - '*on-error': 'BlockdevOnError',
> + '*discard': 'bool', '*on-error': 'BlockdevOnError',
> '*auto-finalize': 'bool', '*auto-dismiss': 'bool' } }
>
> ##
> --
> 1.8.3.1
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK