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From: Shaohua Li <shli@kernel.org>
To: NeilBrown <neilb@suse.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: [md PATCH 4/4] md/bitmap: Don't write bitmap while earlier writes might be in-flight
Date: Fri, 4 Nov 2016 17:33:25 -0700	[thread overview]
Message-ID: <20161105003325.qnmcu363ocbli74x@kernel.org> (raw)
In-Reply-To: <147823836359.6764.7855525110697020696.stgit@noble>

On Fri, Nov 04, 2016 at 04:46:03PM +1100, Neil Brown wrote:
> As we don't wait for writes to complete in bitmap_daemon_work, they
> could still be in-flight when bitmap_unplug writes again.  Or when
> bitmap_daemon_work tries to write again.
> This can be confusing and could risk the wrong data being written last.

Applied the first 3 patches, thanks!

This one seems not completely solving the race condition. It's still possible
bitmap_daemon_work clears BITMAP_PAGE_NEEDWRITE but hasn't dispatch the IO yet,
bitmap_unplug then does nothing and thinks bitmap is updated to disk. Why don't
we add locking here?

Thanks,
Shaohua 

  reply	other threads:[~2016-11-05  0:33 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-04  5:46 [md PATCH 0/4] Assorted minor improvements NeilBrown
2016-11-04  5:46 ` [md PATCH 4/4] md/bitmap: Don't write bitmap while earlier writes might be in-flight NeilBrown
2016-11-05  0:33   ` Shaohua Li [this message]
2016-11-06 22:53     ` NeilBrown
2016-11-07 19:19       ` Shaohua Li
2016-11-07 20:19         ` NeilBrown
2016-11-07 22:57           ` Shaohua Li
2016-11-04  5:46 ` [md PATCH 3/4] md/raid10: abort delayed writes when device fails NeilBrown
2016-11-04  5:46 ` [md PATCH 2/4] md/raid1: " NeilBrown
2016-11-04  5:46 ` [md PATCH 1/4] md: perform async updates for metadata where possible NeilBrown

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