From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: qemu-block@nongnu.org
Cc: qemu-devel@nongnu.org, armbru@redhat.com, jsnow@redhat.com,
mreitz@redhat.com, kwolf@redhat.com, den@openvz.org
Subject: Re: [PATCH 1/2] block: make bdrv_drop_intermediate() less wrong
Date: Tue, 24 Nov 2020 12:39:52 +0300 [thread overview]
Message-ID: <2a272dc2-3fc6-368f-11ee-e126b448f13e@virtuozzo.com> (raw)
In-Reply-To: <20201123201233.9534-2-vsementsov@virtuozzo.com>
23.11.2020 23:12, Vladimir Sementsov-Ogievskiy wrote:
> First, permission update loop tries to do iterations transactionally,
> but the whole update is not transactional: nobody roll-back successful
> loop iterations when some iteration fails.
>
> Second, in the iteration we have nested permission update:
> c->klass->update_filename may point to bdrv_child_cb_update_filename()
> which calls bdrv_backing_update_filename(), which may do node reopen to
> RW.
>
> Permission update system is not prepared to nested updates, at least it
> has intermediate permission-update state stored in BdrvChild
> structures: has_backup_perm, backup_perm and backup_shared_perm.
>
> So, let's first do bdrv_replace_node() (which is more transactional
> than open-coded update in bdrv_drop_intermediate()) and then call
> update_filename() in separate. We still do not rollback changes in case
> of update_filename() failure but it's not much worse than pre-patch
> behavior.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy<vsementsov@virtuozzo.com>
this is accidental patch, ignore it
--
Best regards,
Vladimir
next prev parent reply other threads:[~2020-11-24 9:42 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-23 20:12 [PATCH RFC 00/21] block: update graph permissions update Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 1/2] block: make bdrv_drop_intermediate() less wrong Vladimir Sementsov-Ogievskiy
2020-11-24 9:39 ` Vladimir Sementsov-Ogievskiy [this message]
2020-11-23 20:12 ` [PATCH 01/21] tests/test-bdrv-graph-mod: add test_parallel_exclusive_write Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 2/2] block: assert that permission commit sets same permissions Vladimir Sementsov-Ogievskiy
2020-11-24 9:40 ` Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 02/21] tests/test-bdrv-graph-mod: add test_parallel_perm_update Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 03/21] util: add transactions.c Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 04/21] block: bdrv_refresh_perms: check parents compliance Vladimir Sementsov-Ogievskiy
2020-11-24 9:42 ` Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 05/21] block: refactor bdrv_child* permission functions Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 06/21] block: rewrite bdrv_child_try_set_perm() using bdrv_refresh_perms() Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 07/21] block: inline bdrv_child_*() permission functions calls Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 08/21] block: use topological sort for permission update Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 09/21] block: add bdrv_drv_set_perm transaction action Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 10/21] block: add bdrv_list_* permission update functions Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 11/21] block: add bdrv_replace_child_safe() transaction action Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 12/21] block: return value from bdrv_replace_node() Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 13/21] block: fix bdrv_replace_node_common Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 14/21] block: add bdrv_attach_child_noperm() transaction action Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 15/21] block: split out bdrv_replace_node_noperm() Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 16/21] block: bdrv_append(): don't consume reference Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 17/21] block: bdrv_append(): return status Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 18/21] block: adapt bdrv_append() for inserting filters Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 19/21] block: add bdrv_remove_backing transaction action Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 20/21] block: introduce bdrv_drop_filter() Vladimir Sementsov-Ogievskiy
2020-11-23 20:12 ` [PATCH 21/21] block/backup-top: drop .active Vladimir Sementsov-Ogievskiy
-- strict thread matches above, loose matches on Subject: below --
2020-10-31 12:35 [PATCH 0/2] Fix nested permission update Vladimir Sementsov-Ogievskiy
2020-10-31 12:35 ` [PATCH 1/2] block: make bdrv_drop_intermediate() less wrong Vladimir Sementsov-Ogievskiy
2020-11-05 13:22 ` Max Reitz
2020-11-05 13:24 ` Max Reitz
2020-11-05 15:03 ` Alberto Garcia
2020-11-05 15:14 ` Alberto Garcia
2020-11-06 9:26 ` Vladimir Sementsov-Ogievskiy
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=2a272dc2-3fc6-368f-11ee-e126b448f13e@virtuozzo.com \
--to=vsementsov@virtuozzo.com \
--cc=armbru@redhat.com \
--cc=den@openvz.org \
--cc=jsnow@redhat.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.