[PATCH v3 09/12] Make scsi_mq_prep_fn() call scsi_init_command()

[Bart Van Assche]

This patch reduces code duplication. There are two functional changes
in this patch:
- It causes scsi_mq_prep_fn() to clear driver-private
  command data, just like the already upstream commit 1bad6c4a57ef
  ("scsi: zero per-cmd private driver data for each MQ I/O").
- The initialization of .prot_sdb is moved from scsi_mq_prep_fn()
  into scsi_init_request().

Signed-off-by: Bart Van Assche <bart.vanass...@sandisk.com>
Cc: Hannes Reinecke <h...@suse.com>
Cc: Christoph Hellwig <h...@lst.de>
Cc: Johannes Thumshirn <jthumsh...@suse.de>
---
 drivers/scsi/scsi_lib.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 6b4fb48033fb..ef4e33319407 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1870,36 +1870,21 @@ static int scsi_mq_prep_fn(struct request *req)
        struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
        struct scsi_device *sdev = req->q->queuedata;
        struct Scsi_Host *shost = sdev->host;
-       unsigned char *sense_buf = cmd->sense_buffer;
-       unsigned int unchecked_isa_dma = cmd->flags & SCMD_UNCHECKED_ISA_DMA;
        struct scatterlist *sg;
 
-       /* zero out the cmd, except for the embedded scsi_request */
-       memset((char *)cmd + sizeof(cmd->req), 0,
-               sizeof(*cmd) - sizeof(cmd->req));
+       scsi_init_command(sdev, cmd);
 
        req->special = cmd;
 
        cmd->request = req;
-       cmd->device = sdev;
-       cmd->sense_buffer = sense_buf;
-       cmd->flags = unchecked_isa_dma;
 
        cmd->tag = req->tag;
-
        cmd->prot_op = SCSI_PROT_NORMAL;
 
-       INIT_LIST_HEAD(&cmd->list);
-       INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
-       cmd->jiffies_at_alloc = jiffies;
-
-       scsi_add_cmd_to_list(cmd);
-
        sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
        cmd->sdb.table.sgl = sg;
 
        if (scsi_host_get_prot(shost)) {
-               cmd->prot_sdb = (void *)sg + scsi_mq_sgl_size(shost);
                memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer));
 
                cmd->prot_sdb->table.sgl =
@@ -2025,6 +2010,7 @@ static int scsi_init_request(struct blk_mq_tag_set *set, 
struct request *rq,
        struct Scsi_Host *shost = set->driver_data;
        const bool unchecked_isa_dma = shost->unchecked_isa_dma;
        struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
+       struct scatterlist *sg;
 
        if (unchecked_isa_dma)
                cmd->flags |= SCMD_UNCHECKED_ISA_DMA;
@@ -2033,6 +2019,13 @@ static int scsi_init_request(struct blk_mq_tag_set *set, 
struct request *rq,
        if (!cmd->sense_buffer)
                return -ENOMEM;
        cmd->req.sense = cmd->sense_buffer;
+
+       if (scsi_host_get_prot(shost)) {
+               sg = (void *)cmd + sizeof(struct scsi_cmnd) +
+                       shost->hostt->cmd_size;
+               cmd->prot_sdb = (void *)sg + scsi_mq_sgl_size(shost);
+       }
+
        return 0;
 }
 
-- 
2.12.2