Re: [PATCH] ext4: remove unneeded variable.

[NamJae Jeon]

2011/11/20 Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>:
> On 11/20/2011 01:41 AM, Srivatsa S. Bhat wrote:
>> On 11/11/2011 08:32 PM, Namjae Jeon wrote:
>>> ret2 is not needed in ext4_flush_completed_IO().
>>>
>>
>> Not needed? I went through the code briefly, and I don't agree.
>>
>>> Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxx>
>>> Signed-off-by: Amit Sahrawat <amit.sahrawat83@xxxxxxxxx>
>>> ---
>>> Âfs/ext4/fsync.c | Â Â5 +----
>>> Â1 files changed, 1 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
>>> index 00a2cb7..40397ac 100644
>>> --- a/fs/ext4/fsync.c
>>> +++ b/fs/ext4/fsync.c
>>> @@ -81,7 +81,6 @@ int ext4_flush_completed_IO(struct inode *inode)
>>> Â Â Âstruct ext4_inode_info *ei = EXT4_I(inode);
>>> Â Â Âunsigned long flags;
>>> Â Â Âint ret = 0;
>>> - Â Âint ret2 = 0;
>>>
>>> Â Â Âdump_completed_IO(inode);
>>> Â Â Âspin_lock_irqsave(&ei->i_completed_io_lock, flags);
>>> @@ -105,12 +104,10 @@ int ext4_flush_completed_IO(struct inode *inode)
>>> Â Â Â Â Â Â Â */
>>> Â Â Â Â Â Â Âspin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
>>> Â Â Â Â Â Â Âret = ext4_end_io_nolock(io);
>>> - Â Â Â Â Â Âif (ret < 0)
>>> - Â Â Â Â Â Â Â Â Â Âret2 = ret;
>>> Â Â Â Â Â Â Âspin_lock_irqsave(&ei->i_completed_io_lock, flags);
>>> Â Â Â}
>>> Â Â Âspin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
>>> - Â Âreturn (ret2 < 0) ? ret2 : 0;
>>> + Â Âreturn (ret < 0) ? ret : 0;
>>> Â}
>>
>> Please note that there is a while loop involved here. Which means, that ret2
>> is used to store the last negative value of ret. And due to the loop, ret can
>> be over-written in the next loop iteration, which we can afford, because we
>> have already stored what we need to save, in ret2. And this ret2 value is used
>> to return appropriate value to the caller.
>>
>
> Actually, what I really meant was, removing ret2 as merely "unneeded" might not
> be the right thing to do because once you apply your patch, you end up altering
> the value returned by this function!
>
> If the return value is indeed wrong in the current code, you should rather
> be saying that this is a bug fix, with appropriate justification IMO.
>
Thanks for your review. My thinking was reaching for to while loop().
I will remember your advice.
Thanks Srivatsa.
> Thanks,
> Srivatsa S. Bhat
>
>
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