linux-ext4 - Re: [PATCH 2/2] ext4: Remove code duplication in ext4_get_block_write

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Date:	Fri, 9 Nov 2012 09:51:35 -0800
From:	Anatol Pomozov <anatol.pomozov@...il.com>
To:	"Theodore Ts'o" <tytso@....edu>
Cc:	wenqing.lz@...bao.com, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/2] ext4: Remove code duplication in ext4_get_block_write_nolock()

Hi

On Fri, Nov 9, 2012 at 9:29 AM, Theodore Ts'o <tytso@....edu> wrote:
> There's a really serious bug in this patch which I didn't notice at
> first:
>
>> --- a/fs/ext4/inode.c
>> +++ b/fs/ext4/inode.c
>> @@ -683,7 +683,7 @@ static int _ext4_get_block(struct inode *inode, sector_t iblock,
>>       map.m_lblk = iblock;
>>       map.m_len = bh->b_size >> inode->i_blkbits;
>>
>> -     if (flags && !handle) {
>> +     if (flags && !(flags | EXT4_GET_BLOCKS_NO_LOCK) && !handle) {
>                             ^^^
>
> This should obviously read:
>
>         if (flags && !(flags & EXT4_GET_BLOCKS_NO_LOCK) && !handle) {

D'oh... You are right..

> Otherwise xfstests #91 will blow out with a circular lockdep warning.
>
> As a reminder, please do make sure you compile with lockdep enabled
> when you run your tests; it's found more than one bug for me!

I though I tested with and without debug options enabled. Maybe I
missed lockdep option somehow, next time i'll make sure that it is
enabled.

Thanks for catching it.

>
>                                               - Ted
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