sd: factor out a sd_set_special_bvec helper

Add a helper for setting up the special_bvec instead of open coding it
in three place, and use the new bvec_set_page helper to initialize
special_vec.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20230203150634.3199647-5-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/scsi/sd.c

@@ -831,6 +831,19 @@ static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode)
 	blk_queue_max_discard_sectors(q, max_blocks * (logical_block_size >> 9));
 }
 
+static void *sd_set_special_bvec(struct request *rq, unsigned int data_len)
+{
+	struct page *page;
+
+	page = mempool_alloc(sd_page_pool, GFP_ATOMIC);
+	if (!page)
+		return NULL;
+	clear_highpage(page);
+	bvec_set_page(&rq->special_vec, page, data_len, 0);
+	rq->rq_flags |= RQF_SPECIAL_PAYLOAD;
+	return bvec_virt(&rq->special_vec);
+}
+
 static blk_status_t sd_setup_unmap_cmnd(struct scsi_cmnd *cmd)
 {
 	struct scsi_device *sdp = cmd->device;
@@ -841,19 +854,14 @@ static blk_status_t sd_setup_unmap_cmnd(struct scsi_cmnd *cmd)
 	unsigned int data_len = 24;
 	char *buf;
 
-	rq->special_vec.bv_page = mempool_alloc(sd_page_pool, GFP_ATOMIC);
-	if (!rq->special_vec.bv_page)
+	buf = sd_set_special_bvec(rq, data_len);
+	if (!buf)
 		return BLK_STS_RESOURCE;
-	clear_highpage(rq->special_vec.bv_page);
-	rq->special_vec.bv_offset = 0;
-	rq->special_vec.bv_len = data_len;
-	rq->rq_flags |= RQF_SPECIAL_PAYLOAD;
 
 	cmd->cmd_len = 10;
 	cmd->cmnd[0] = UNMAP;
 	cmd->cmnd[8] = 24;
 
-	buf = bvec_virt(&rq->special_vec);
 	put_unaligned_be16(6 + 16, &buf[0]);
 	put_unaligned_be16(16, &buf[2]);
 	put_unaligned_be64(lba, &buf[8]);
@@ -876,13 +884,8 @@ static blk_status_t sd_setup_write_same16_cmnd(struct scsi_cmnd *cmd,
 	u32 nr_blocks = sectors_to_logical(sdp, blk_rq_sectors(rq));
 	u32 data_len = sdp->sector_size;
 
-	rq->special_vec.bv_page = mempool_alloc(sd_page_pool, GFP_ATOMIC);
-	if (!rq->special_vec.bv_page)
+	if (!sd_set_special_bvec(rq, data_len))
 		return BLK_STS_RESOURCE;
-	clear_highpage(rq->special_vec.bv_page);
-	rq->special_vec.bv_offset = 0;
-	rq->special_vec.bv_len = data_len;
-	rq->rq_flags |= RQF_SPECIAL_PAYLOAD;
 
 	cmd->cmd_len = 16;
 	cmd->cmnd[0] = WRITE_SAME_16;
@@ -908,13 +911,8 @@ static blk_status_t sd_setup_write_same10_cmnd(struct scsi_cmnd *cmd,
 	u32 nr_blocks = sectors_to_logical(sdp, blk_rq_sectors(rq));
 	u32 data_len = sdp->sector_size;
 
-	rq->special_vec.bv_page = mempool_alloc(sd_page_pool, GFP_ATOMIC);
-	if (!rq->special_vec.bv_page)
+	if (!sd_set_special_bvec(rq, data_len))
 		return BLK_STS_RESOURCE;
-	clear_highpage(rq->special_vec.bv_page);
-	rq->special_vec.bv_offset = 0;
-	rq->special_vec.bv_len = data_len;
-	rq->rq_flags |= RQF_SPECIAL_PAYLOAD;
 
 	cmd->cmd_len = 10;
 	cmd->cmnd[0] = WRITE_SAME;