qemu-devel.nongnu.org archive mirror
 help / color / mirror / Atom feed
From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: Max Reitz <mreitz@redhat.com>,
	"qemu-block@nongnu.org" <qemu-block@nongnu.org>
Cc: Kevin Wolf <kwolf@redhat.com>, Alberto Garcia <berto@igalia.com>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [PATCH 14/22] quorum: Stop marking it as a filter
Date: Thu, 26 Sep 2019 12:43:11 +0000	[thread overview]
Message-ID: <e5c4d8ed-7196-ec0d-92d7-6766610b6b80@virtuozzo.com> (raw)
In-Reply-To: <20190920152804.12875-15-mreitz@redhat.com>

20.09.2019 18:27, Max Reitz wrote:
> Quorum is not a filter, for example because it cannot guarantee which of
> its children will serve the next request.  Thus, any of its children may
> differ from the data visible to quorum's parents.
> 
> We have other filters with multiple children, but they differ in this
> aspect:
> 
> - blkverify quits the whole qemu process if its children differ.  As
>    such, we can always skip it when we want to skip it (as a filter node)
>    by going to any of its children.  Both have the same data.
> 
> - replication generally serves requests from bs->file, so this is its
>    only actually filtered child.
> 
> - Block job filters currently only have one child, but they will
>    probably get more children in the future.  Still, they will always
>    have only one actually filtered child.
> 
> Having "filters" as a dedicated node category only makes sense if you
> can skip them by going to a one fixed child that always shows the same
> data as the filter node.  Quorum cannot fulfill this, so it is not a
> filter.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

> ---
>   block/quorum.c | 1 -
>   1 file changed, 1 deletion(-)
> 
> diff --git a/block/quorum.c b/block/quorum.c
> index 7a8f8b5475..7f56b4df7c 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -1237,7 +1237,6 @@ static BlockDriver bdrv_quorum = {
>   
>       .bdrv_child_perm                    = quorum_child_perm,
>   
> -    .is_filter                          = true,
>       .bdrv_recurse_can_replace           = quorum_recurse_can_replace,
>   
>       .strong_runtime_opts                = quorum_strong_runtime_opts,
> 


-- 
Best regards,
Vladimir

  reply	other threads:[~2019-09-26 12:44 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-20 15:27 [PATCH 00/22] block: Fix check_to_replace_node() Max Reitz
2019-09-20 15:27 ` [PATCH 01/22] blockdev: Allow external snapshots everywhere Max Reitz
2019-09-25 11:45   ` Vladimir Sementsov-Ogievskiy
2019-09-20 15:27 ` [PATCH 02/22] blockdev: Allow resizing everywhere Max Reitz
2019-09-25 11:46   ` Vladimir Sementsov-Ogievskiy
2019-09-20 15:27 ` [PATCH 03/22] block: Drop bdrv_is_first_non_filter() Max Reitz
2019-09-25 11:46   ` Vladimir Sementsov-Ogievskiy
2019-09-20 15:27 ` [PATCH 04/22] iotests: Let 041 use -blockdev for quorum children Max Reitz
2019-09-25 11:51   ` Vladimir Sementsov-Ogievskiy
2019-09-20 15:27 ` [PATCH 05/22] quorum: Fix child permissions Max Reitz
2019-09-25 11:56   ` Vladimir Sementsov-Ogievskiy
2019-09-26 11:02     ` Max Reitz
2019-09-20 15:27 ` [PATCH 06/22] block: Add bdrv_recurse_can_replace() Max Reitz
2019-09-25 12:39   ` Vladimir Sementsov-Ogievskiy
2019-09-26 11:03     ` Max Reitz
2019-09-20 15:27 ` [PATCH 07/22] blkverify: Implement .bdrv_recurse_can_replace() Max Reitz
2019-09-25 12:56   ` Vladimir Sementsov-Ogievskiy
2019-09-26 11:06     ` Max Reitz
2019-09-20 15:27 ` [PATCH 08/22] quorum: Store children in own structure Max Reitz
2019-09-25 13:21   ` Vladimir Sementsov-Ogievskiy
2019-09-26 11:07     ` Max Reitz
2019-09-20 15:27 ` [PATCH 09/22] quorum: Add QuorumChild.to_be_replaced Max Reitz
2019-09-25 13:45   ` Vladimir Sementsov-Ogievskiy
2019-09-26 11:13     ` Max Reitz
2019-09-20 15:27 ` [PATCH 10/22] quorum: Implement .bdrv_recurse_can_replace() Max Reitz
2019-09-25 13:39   ` Vladimir Sementsov-Ogievskiy
2019-09-26 11:12     ` Max Reitz
2019-09-25 14:12   ` Vladimir Sementsov-Ogievskiy
2019-09-26 11:17     ` Max Reitz
2019-09-25 14:14   ` Vladimir Sementsov-Ogievskiy
2019-09-20 15:27 ` [PATCH 11/22] block: Use bdrv_recurse_can_replace() Max Reitz
2019-09-20 15:27 ` [PATCH 12/22] block: Remove bdrv_recurse_is_first_non_filter() Max Reitz
2019-09-25 14:16   ` Vladimir Sementsov-Ogievskiy
2019-09-20 15:27 ` [PATCH 13/22] mirror: Double-check immediately before replacing Max Reitz
2019-09-20 15:27 ` [PATCH 14/22] quorum: Stop marking it as a filter Max Reitz
2019-09-26 12:43   ` Vladimir Sementsov-Ogievskiy [this message]
2019-09-20 15:27 ` [PATCH 15/22] mirror: Prevent loops Max Reitz
2019-09-26 13:08   ` Vladimir Sementsov-Ogievskiy
2019-10-02 12:36     ` Max Reitz
2019-09-20 15:27 ` [PATCH 16/22] iotests: Use complete_and_wait() in 155 Max Reitz
2019-09-26 13:11   ` Vladimir Sementsov-Ogievskiy
2019-09-20 15:27 ` [PATCH 17/22] iotests: Add VM.assert_block_path() Max Reitz
2019-09-26 14:07   ` Vladimir Sementsov-Ogievskiy
2019-10-02 12:40     ` Max Reitz
2019-10-02 13:51       ` Vladimir Sementsov-Ogievskiy
2019-09-20 15:28 ` [PATCH 18/22] iotests: Resolve TODOs in 041 Max Reitz
2019-09-26 14:09   ` Vladimir Sementsov-Ogievskiy
2019-09-20 15:28 ` [PATCH 19/22] iotests: Use self.image_len in TestRepairQuorum Max Reitz
2019-09-26 14:13   ` Vladimir Sementsov-Ogievskiy
2019-10-02 12:42     ` Max Reitz
2019-09-20 15:28 ` [PATCH 20/22] iotests: Add tests for invalid Quorum @replaces Max Reitz
2019-09-26 14:30   ` Vladimir Sementsov-Ogievskiy
2019-10-02 12:43     ` Max Reitz
2019-09-20 15:28 ` [PATCH 21/22] iotests: Check that @replaces can replace filters Max Reitz
2019-09-26 14:42   ` Vladimir Sementsov-Ogievskiy
2019-09-20 15:28 ` [PATCH 22/22] iotests: Mirror must not attempt to create loops Max Reitz
2019-09-26 15:03   ` Vladimir Sementsov-Ogievskiy
2019-10-02 12:46     ` Max Reitz

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=e5c4d8ed-7196-ec0d-92d7-6766610b6b80@virtuozzo.com \
    --to=vsementsov@virtuozzo.com \
    --cc=berto@igalia.com \
    --cc=kwolf@redhat.com \
    --cc=mreitz@redhat.com \
    --cc=qemu-block@nongnu.org \
    --cc=qemu-devel@nongnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).