linux-ext4 - Re: [PATCH 1/2] ext4: Do not allow retry alloc loop under open transaction

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Message-ID: <877hqtdx2w.fsf@openvz.org>
Date:	Thu, 04 Feb 2010 15:06:31 +0300
From:	Dmitry Monakhov <dmonakhov@...nvz.org>
To:	"Aneesh Kumar K. V" <aneesh.kumar@...ux.vnet.ibm.com>
Cc:	linux-ext4@...r.kernel.org, tytso@....edu
Subject: Re: [PATCH 1/2] ext4: Do not allow retry alloc loop under open transaction

"Aneesh Kumar K. V" <aneesh.kumar@...ux.vnet.ibm.com> writes:

> On Wed, 03 Feb 2010 21:27:31 +0300, Dmitry Monakhov <dmonakhov@...nvz.org> wrote:
>> 
>> Some times we call ->write_begin() with opened journal
>> but write_begin() may internally call ext4_should_retry_alloc()
>> in case of ENOSPC, which result in deadlock.
>> This patch introduce new AOP_FLAG which should be tested on retry
>> alloc path.
>> 
>
> Can you explain this further. We do a journal_stop before
> ext4_should_retry_alloc. So not sure about the deadlock.
move_extent_per_page
 ext4_journal_start  -> current->journal_info != NULL
 ->write_begin
    ext4_journal_start
    ext4_journal_stop
    ext4_should_retry_alloc : here current->journal_info != NULL

Sorry i've missed the fact that ext4_should_retry_alloc() check 
for current->journal_info and skip running transaction in that case.
Seems what this check was added long time ago, but i miss it.
So this patch is useless.
>
> -aneesh
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