linux-kernel - Re: [PATCH] xfs: donot need to check return value of xlog

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Message-ID: <b83283b2-39b3-c659-1b9f-f774af47d3f8@huawei.com>
Date:   Wed, 31 Aug 2022 17:48:35 +0800
From:   Zhiqiang Liu <liuzhiqiang26@...wei.com>
To:     Eric Sandeen <sandeen@...deen.net>,
        "Darrick J. Wong" <djwong@...nel.org>, <linux-xfs@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     linfeilong <linfeilong@...wei.com>,
        wuguanghao <wuguanghao3@...wei.com>
Subject: Re: [PATCH] xfs: donot need to check return value of xlog_kvmalloc()


On 2022/8/30 0:06, Eric Sandeen wrote:
> On 8/22/22 6:46 AM, Zhiqiang Liu wrote:
>> In xfs_attri_log_nameval_alloc(), xlog_kvmalloc() is called
>> to alloc memory, which will always return
>> successfully, so we donot need to check return value.
>>
>> Signed-off-by: Zhiqiang Liu <liuzhiqiang26@...wei.com>
> I think this is fine. xlog_kvmalloc loops until success, and its other
> caller does not check the return value.
>
> This isn't really strictly a fix (it's harmless) but it "fixes"
>
> Fixes: commit 4183e4f27f402 ("xfs: share xattr name and value buffers when logging xattr updates")
>
> Reviewed-by: Eric Sandeen <sandeen@...hat.com>

Thanks for your reply.

Before xlog_kvmalloc was changed to "loops until success", the sanity check was necessary.

As you said, this isn't really strictly a fix, so I think we should not add the Fix tag.

> That said, I think that xfs_attri_log_nameval_alloc() also cannot fail, so
> perhaps its callers don't need checks either?
Yes, you are right. I will clean it up in the V2 patch.

>> ---
>>  fs/xfs/xfs_attr_item.c | 2 --
>>  1 file changed, 2 deletions(-)
>>
>> diff --git a/fs/xfs/xfs_attr_item.c b/fs/xfs/xfs_attr_item.c
>> index 5077a7ad5646..667e151a2bca 100644
>> --- a/fs/xfs/xfs_attr_item.c
>> +++ b/fs/xfs/xfs_attr_item.c
>> @@ -86,8 +86,6 @@ xfs_attri_log_nameval_alloc(
>>  	 */
>>  	nv = xlog_kvmalloc(sizeof(struct xfs_attri_log_nameval) +
>>  					name_len + value_len);
>> -	if (!nv)
>> -		return nv;
>>
>>  	nv->name.i_addr = nv + 1;
>>  	nv->name.i_len = name_len;
> .