Re: [PATCH 1/3] md: set MD_CHANGE_PENDING in a atomic region

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From	Shaohua Li <shli@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/3] md: set MD_CHANGE_PENDING in a atomic region
Date	Mon, 09 May 2016 00:20:02 +0200
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On Tue, May 03, 2016 at 10:22:13PM -0400, Guoqing Jiang wrote:
> Some code waits for a metadata update by:
> 
> 1. flagging that it is needed (MD_CHANGE_DEVS or MD_CHANGE_CLEAN)
> 2. setting MD_CHANGE_PENDING and waking the management thread
> 3. waiting for MD_CHANGE_PENDING to be cleared
> 
> If the first two are done without locking, the code in md_update_sb()
> which checks if it needs to repeat might test if an update is needed
> before step 1, then clear MD_CHANGE_PENDING after step 2, resulting
> in the wait returning early.
> 
> So make sure all places that set MD_CHANGE_PENDING are atomicial, and
> bit_clear_unless (suggested by Neil) is introduced for the purpose.

Applied the 3, thanks!

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[PATCH 1/3] md: set MD_CHANGE_PENDING in a atomic region Guoqing Jiang <gqjiang@suse.com> - 2016-05-04 04:30 +0200
  Re: [PATCH 1/3] md: set MD_CHANGE_PENDING in a atomic region Shaohua Li <shli@kernel.org> - 2016-05-09 00:20 +0200

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