Re: [PATCH v2 1/2] target/rd: reduce code duplication in rd_execute_rw()

From: Akinobu Mita <akinobu.mita@gmail.com>
To: Sagi Grimberg <sagig@dev.mellanox.co.il>
Cc: target-devel@vger.kernel.org,
	Nicholas Bellinger <nab@linux-iscsi.org>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Christoph Hellwig <hch@lst.de>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] target/rd: reduce code duplication in rd_execute_rw()
Date: Mon, 6 Apr 2015 20:16:41 +0900	[thread overview]
Message-ID: <CAC5umyhG0oinXnsyqXwNc1cqWU3ixHLwB8jbQt=Vt2x=cC3Kyg@mail.gmail.com> (raw)
In-Reply-To: <55223908.6080607@dev.mellanox.co.il>

2015-04-06 16:43 GMT+09:00 Sagi Grimberg <sagig@dev.mellanox.co.il>:
> On 4/5/2015 5:59 PM, Akinobu Mita wrote:
>>
>> Factor out code duplication in rd_execute_rw() into a helper function
>> rd_do_prot_rw().  This change is required to minimize the forthcoming
>> fix in rd_do_prot_rw().
>>
>> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
>> Cc: Nicholas Bellinger <nab@linux-iscsi.org>
>> Cc: Sagi Grimberg <sagig@dev.mellanox.co.il>
>> Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
>> Cc: Christoph Hellwig <hch@lst.de>
>> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
>> Cc: target-devel@vger.kernel.org
>> Cc: linux-scsi@vger.kernel.org
>> ---
>> * v2
>> - Pass dif_verify() function pointer to helper function instead of
>> is_write,
>>    suggested by Sagi Grimberg.
>>
>>   drivers/target/target_core_rd.c | 66
>> ++++++++++++++++++++---------------------
>>   1 file changed, 32 insertions(+), 34 deletions(-)
>>
>> diff --git a/drivers/target/target_core_rd.c
>> b/drivers/target/target_core_rd.c
>> index 98e83ac..ac5e8d2 100644
>> --- a/drivers/target/target_core_rd.c
>> +++ b/drivers/target/target_core_rd.c
>> @@ -382,6 +382,36 @@ static struct rd_dev_sg_table
>> *rd_get_prot_table(struct rd_dev *rd_dev, u32 page
>>         return NULL;
>>   }
>>
>> +typedef sense_reason_t (*dif_verify)(struct se_cmd *, sector_t, unsigned
>> int,
>> +                                    unsigned int, struct scatterlist *,
>> int);
>> +
>> +static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, dif_verify
>> dif_verify)
>> +{
>> +       struct se_device *se_dev = cmd->se_dev;
>> +       struct rd_dev *dev = RD_DEV(se_dev);
>> +       struct rd_dev_sg_table *prot_table;
>> +       struct scatterlist *prot_sg;
>> +       u32 sectors = cmd->data_length / se_dev->dev_attrib.block_size;
>> +       u32 prot_offset, prot_page;
>> +       u64 tmp;
>> +       sense_reason_t rc;
>> +
>> +       tmp = cmd->t_task_lba * se_dev->prot_length;
>> +       prot_offset = do_div(tmp, PAGE_SIZE);
>> +       prot_page = tmp;
>> +
>> +       prot_table = rd_get_prot_table(dev, prot_page);
>> +       if (!prot_table)
>> +               return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>> +
>> +       prot_sg = &prot_table->sg_table[prot_page -
>> +                                       prot_table->page_start_offset];
>> +
>> +       rc = dif_verify(cmd, cmd->t_task_lba, sectors, 0, prot_sg,
>> prot_offset);
>> +
>> +       return rc;
>
>
> Nit, Given there is no action on the returned rc, this can be reduced to:
>         return dif_verify();

You are right,  but the patch 2/2 inserts the lines to release
temporary prot_sg before return statement, so assignment and return
statements will be both required in the end.