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Re: [Qemu-block] [PATCH v10 08/16] block: Support streaming to an interm
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-block] [PATCH v10 08/16] block: Support streaming to an intermediate layer |
Date: |
Wed, 12 Oct 2016 16:23:05 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 06.10.2016 um 15:02 hat Alberto Garcia geschrieben:
> This makes sure that the image we are streaming into is open in
> read-write mode during the operation.
>
> Operation blockers are also set in all intermediate nodes, since they
> will be removed from the chain afterwards.
>
> Finally, this also unblocks the stream operation in backing files.
>
> Signed-off-by: Alberto Garcia <address@hidden>
> ---
> block.c | 4 +++-
> block/stream.c | 24 ++++++++++++++++++++++++
> 2 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/block.c b/block.c
> index c80b528..8255d75 100644
> --- a/block.c
> +++ b/block.c
> @@ -1428,9 +1428,11 @@ void bdrv_set_backing_hd(BlockDriverState *bs,
> BlockDriverState *backing_hd)
> backing_hd->drv ? backing_hd->drv->format_name : "");
>
> bdrv_op_block_all(backing_hd, bs->backing_blocker);
> - /* Otherwise we won't be able to commit due to check in bdrv_commit */
> + /* Otherwise we won't be able to commit or stream */
> bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
> bs->backing_blocker);
> + bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
> + bs->backing_blocker);
> /*
> * We do backup in 3 ways:
> * 1. drive backup
> diff --git a/block/stream.c b/block/stream.c
> index 3187481..b8ab89a 100644
> --- a/block/stream.c
> +++ b/block/stream.c
> @@ -37,6 +37,7 @@ typedef struct StreamBlockJob {
> BlockDriverState *base;
> BlockdevOnError on_error;
> char *backing_file_str;
> + int bs_flags;
> } StreamBlockJob;
>
> static int coroutine_fn stream_populate(BlockBackend *blk,
> @@ -81,6 +82,11 @@ static void stream_complete(BlockJob *job, void *opaque)
> bdrv_set_backing_hd(bs, base);
> }
>
> + /* Reopen the image back in read-only mode if necessary */
> + if (s->bs_flags != bdrv_get_flags(bs)) {
> + bdrv_reopen(bs, s->bs_flags, NULL);
> + }
> +
> g_free(s->backing_file_str);
> block_job_completed(&s->common, data->ret);
> g_free(data);
> @@ -220,6 +226,8 @@ void stream_start(const char *job_id, BlockDriverState
> *bs,
> BlockCompletionFunc *cb, void *opaque, Error **errp)
> {
> StreamBlockJob *s;
> + BlockDriverState *iter;
> + int orig_bs_flags;
>
> s = block_job_create(job_id, &stream_job_driver, bs, speed,
> cb, opaque, errp);
> @@ -227,8 +235,24 @@ void stream_start(const char *job_id, BlockDriverState
> *bs,
> return;
> }
>
> + /* Make sure that the image is opened in read-write mode */
> + orig_bs_flags = bdrv_get_flags(bs);
> + if (!(orig_bs_flags & BDRV_O_RDWR)) {
> + if (bdrv_reopen(bs, orig_bs_flags | BDRV_O_RDWR, errp) != 0) {
> + block_job_unref(&s->common);
> + return;
> + }
> + }
> +
> + /* Block all intermediate nodes between bs and base, because they
> + * will disappear from the chain after this operation */
> + for (iter = backing_bs(bs); iter && iter != base; iter =
> backing_bs(iter)) {
> + block_job_add_bdrv(&s->common, iter);
> + }
In patch 6, you had a comment that the top node must be blocked as well
because its backing file string will be updated. Isn't it the same for
streaming?
> s->base = base;
> s->backing_file_str = g_strdup(backing_file_str);
> + s->bs_flags = orig_bs_flags;
>
> s->on_error = on_error;
> s->common.co = qemu_coroutine_create(stream_run, s);
Kevin
[Qemu-block] [PATCH v10 04/16] block: Use block_job_add_bdrv() in backup_start(), Alberto Garcia, 2016/10/06
[Qemu-block] [PATCH v10 05/16] block: Check blockers in all nodes involved in a block-commit job, Alberto Garcia, 2016/10/06
[Qemu-block] [PATCH v10 10/16] docs: Document how to stream to an intermediate layer, Alberto Garcia, 2016/10/06
[Qemu-block] [PATCH v10 14/16] qemu-iotests: Test block-stream and block-commit in parallel, Alberto Garcia, 2016/10/06