block: pass io_comp_batch to rq_end_io_fn callback

Add a third parameter 'const struct io_comp_batch *' to the rq_end_io_fn
callback signature. This allows end_io handlers to access the completion
batch context when requests are completed via blk_mq_end_request_batch().

The io_comp_batch is passed from blk_mq_end_request_batch(), while NULL
is passed from __blk_mq_end_request() and blk_mq_put_rq_ref() which don't
have batch context.

This infrastructure change enables drivers to detect whether they're
being called from a batched completion path (like iopoll) and access
additional context stored in the io_comp_batch.

Update all rq_end_io_fn implementations:
- block/blk-mq.c: blk_end_sync_rq
- block/blk-flush.c: flush_end_io, mq_flush_data_end_io
- drivers/nvme/host/ioctl.c: nvme_uring_cmd_end_io
- drivers/nvme/host/core.c: nvme_keep_alive_end_io
- drivers/nvme/host/pci.c: abort_endio, nvme_del_queue_end, nvme_del_cq_end
- drivers/nvme/target/passthru.c: nvmet_passthru_req_done
- drivers/scsi/scsi_error.c: eh_lock_door_done
- drivers/scsi/sg.c: sg_rq_end_io
- drivers/scsi/st.c: st_scsi_execute_end
- drivers/target/target_core_pscsi.c: pscsi_req_done
- drivers/md/dm-rq.c: end_clone_request

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 8 insertions, 4 deletions

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index f869108fd969..1e93390c5a82 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -2085,7 +2085,8 @@ maybe_retry:
 }
 
 static enum rq_end_io_ret eh_lock_door_done(struct request *req,
-					    blk_status_t status)
+					    blk_status_t status,
+					    const struct io_comp_batch *iob)
 {
 	blk_mq_free_request(req);
 	return RQ_END_IO_NONE;
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 57fba34832ad..1a521f9d821a 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -177,7 +177,8 @@ typedef struct sg_device { /* holds the state of each scsi generic device */
 } Sg_device;
 
 /* tasklet or soft irq callback */
-static enum rq_end_io_ret sg_rq_end_io(struct request *rq, blk_status_t status);
+static enum rq_end_io_ret sg_rq_end_io(struct request *rq, blk_status_t status,
+				       const struct io_comp_batch *iob);
 static int sg_start_req(Sg_request *srp, unsigned char *cmd);
 static int sg_finish_rem_req(Sg_request * srp);
 static int sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size);
@@ -1309,7 +1310,8 @@ sg_rq_end_io_usercontext(struct work_struct *work)
  * level when a command is completed (or has failed).
  */
 static enum rq_end_io_ret
-sg_rq_end_io(struct request *rq, blk_status_t status)
+sg_rq_end_io(struct request *rq, blk_status_t status,
+	     const struct io_comp_batch *iob)
 {
 	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
 	struct sg_request *srp = rq->end_io_data;
diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 168f25e4aaa3..8aeaa3b68c25 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -525,7 +525,8 @@ static void st_do_stats(struct scsi_tape *STp, struct request *req)
 }
 
 static enum rq_end_io_ret st_scsi_execute_end(struct request *req,
-					      blk_status_t status)
+					      blk_status_t status,
+					      const struct io_comp_batch *iob)
 {
 	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req);
 	struct st_request *SRpnt = req->end_io_data;