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From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: qemu-block@nongnu.org
Cc: kwolf@redhat.com, fam@euphon.net, qemu-devel@nongnu.org,
	mreitz@redhat.com, stefanha@redhat.com, den@openvz.org
Subject: Re: [PATCH v2 0/9] block/io: safer inc/dec in_flight sections
Date: Tue, 19 May 2020 14:18:55 +0300	[thread overview]
Message-ID: <2350408e-23e6-9dcc-0b3a-ff6546df2c86@virtuozzo.com> (raw)
In-Reply-To: <20200427143907.5710-1-vsementsov@virtuozzo.com>

27.04.2020 17:38, Vladimir Sementsov-Ogievskiy wrote:
> Hi all!
> 
> This is inspired by Kevin's
> "block: Fix blk->in_flight during blk_wait_while_drained()" series.
> 
> So, like it's now done for block-backends, let's expand
> in_flight-protected sections for bdrv_ interfaces, including
> coroutine_enter and BDRV_POLL_WHILE loop into these sections.
> 

OK, let's postpone this thing.

1. Idea to move ind/dec out of coroutine seems wrong, it leads to dead-lock, as shown in backtrace in my answer to 5/9.

2. Idea to keep request inside only one pair of ind/dec is probably an extra restriction in bdrv layer (I just blindly followed how it was done in blk layer by Kevin)

3. We still may have a theoretical race between request start and drained section start, but it needs another audit and smarter solution.

So, seems that we should not apply these series as it is, sorry for the noise. I think, I'll resend my 64bit-block-layer series based on master instead of this one.

-- 
Best regards,
Vladimir


      parent reply	other threads:[~2020-05-19 11:20 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-27 14:38 [PATCH v2 0/9] block/io: safer inc/dec in_flight sections Vladimir Sementsov-Ogievskiy
2020-04-27 14:38 ` [PATCH v2 1/9] block/io: refactor bdrv_is_allocated_above to run only one coroutine Vladimir Sementsov-Ogievskiy
2020-05-01 21:25   ` Eric Blake
2020-04-27 14:39 ` [PATCH v2 2/9] block/io: refactor bdrv_co_ioctl: move aio stuff to corresponding block Vladimir Sementsov-Ogievskiy
2020-04-27 14:39 ` [PATCH v2 3/9] block/io: move flush and pdiscard stuff down Vladimir Sementsov-Ogievskiy
2020-04-27 14:39 ` [PATCH v2 4/9] block/io: move bdrv_rw_co_entry and friends down Vladimir Sementsov-Ogievskiy
2020-04-27 14:39 ` [PATCH v2 5/9] block/io: expand in_flight inc/dec section: simple cases Vladimir Sementsov-Ogievskiy
2020-05-01 21:43   ` Eric Blake
2020-05-06  7:02   ` Vladimir Sementsov-Ogievskiy
2020-05-18 18:21     ` Vladimir Sementsov-Ogievskiy
2020-05-19 10:52     ` Kevin Wolf
2020-05-19 11:06       ` Vladimir Sementsov-Ogievskiy
2020-05-19 11:16         ` Kevin Wolf
2020-05-19 11:25           ` Vladimir Sementsov-Ogievskiy
2020-05-19 14:01             ` Vladimir Sementsov-Ogievskiy
2020-05-19 14:33               ` Kevin Wolf
2020-05-19 16:54                 ` Vladimir Sementsov-Ogievskiy
2020-05-19 11:04   ` Kevin Wolf
2020-04-27 14:39 ` [PATCH v2 6/9] block/io: expand in_flight inc/dec section: block-status Vladimir Sementsov-Ogievskiy
2020-05-01 22:00   ` Eric Blake
2020-05-19 10:57     ` Kevin Wolf
2020-04-27 14:39 ` [PATCH v2 7/9] block/io: add bdrv_do_pwrite_zeroes Vladimir Sementsov-Ogievskiy
2020-05-01 22:05   ` Eric Blake
2020-04-27 14:39 ` [PATCH v2 8/9] block/io: move bdrv_make_zero under block-status Vladimir Sementsov-Ogievskiy
2020-04-27 14:39 ` [PATCH v2 9/9] block/io: expand in_flight inc/dec section: bdrv_make_zero Vladimir Sementsov-Ogievskiy
2020-05-01 22:08   ` Eric Blake
2020-05-19 11:18 ` Vladimir Sementsov-Ogievskiy [this message]

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