[PATCH RFC v3 04/22] scsi: core: Add support to send reserved commands

John Garry
2022-10-25T09:48:35Z

Add a method to queue reserved commands.

Signed-off-by: John Garry <john.garry@huawei.com>
---
drivers/scsi/hosts.c | 6 ++++++
drivers/scsi/scsi_lib.c | 25 +++++++++++++++++++++++++
include/scsi/scsi_host.h | 1 +
3 files changed, 32 insertions(+)

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index db89afc37bc9..78968553089f 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -230,6 +230,12 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
goto fail;
}

+ if (shost->nr_reserved_cmds && !sht->reserved_queuecommand) {
+ shost_printk(KERN_ERR, shost,
+ "nr_reserved_cmds set but no method to queue\n");
+ goto fail;
+ }
+
/* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */
shost->cmd_per_lun = min_t(int, shost->cmd_per_lun,
shost->can_queue);
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index a8c4e7c037ae..08015c42c326 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1428,6 +1428,16 @@ static void scsi_complete(struct request *rq)
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
enum scsi_disposition disposition;

+ if (blk_mq_is_reserved_rq(rq)) {
+ struct scsi_device *sdev = cmd->device;
+
+ scsi_mq_uninit_cmd(cmd);
+ scsi_device_unbusy(sdev, cmd);
+ __blk_mq_end_request(rq, 0);
+
+ return;
+ }
+
INIT_LIST_HEAD(&cmd->eh_entry);

atomic_inc(&cmd->device->iodone_cnt);
@@ -1718,6 +1728,21 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
blk_status_t ret;
int reason;

+ if (blk_mq_is_reserved_rq(req)) {
+ if (!(req->rq_flags & RQF_DONTPREP)) {
+ ret = scsi_prepare_cmd(req);
+ if (ret != BLK_STS_OK)
+ goto out_dec_host_busy;
+
+ req->rq_flags |= RQF_DONTPREP;
+ } else {
+ clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
+ }
+ blk_mq_start_request(req);
+
+ return shost->hostt->reserved_queuecommand(shost, cmd);
+ }
+
WARN_ON_ONCE(cmd->budget_token < 0);

/*
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 91678c77398e..a39f36aa0b0d 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -73,6 +73,7 @@ struct scsi_host_template {
* STATUS: REQUIRED
*/
int (* queuecommand)(struct Scsi_Host *, struct scsi_cmnd *);
+ int (*reserved_queuecommand)(struct Scsi_Host *, struct scsi_cmnd *);

/*
* The commit_rqs function is used to trigger a hardware
--
2.35.3