[PATCH v4 5/8] scsi: scsi_debug: Split resp_write_dt0()

[Bart Van Assche <bvanassche@acm.org>]

Prepare for enabling lock context analysis by eliminating conditional
locking.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/scsi_debug.c | 139 ++++++++++++++++++++++++--------------
 1 file changed, 87 insertions(+), 52 deletions(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index c66f8556896d..685949aedf9a 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -5094,6 +5094,85 @@ static int corrupt_lbas(struct sdebug_dev_info *devip, u64 lba, u32 num,
 	return error;
 }
 
+/*
+ * Returns 0 upon success or -1 with *scsi_status set to a SCSI status code upon
+ * failure.
+ */
+static int __resp_write_dt0_dix(struct scsi_cmnd *scp,
+				u64 lba, u32 num,
+				u32 ei_lba, int *scsi_status)
+{
+	switch (prot_verify_write(scp, lba, num, ei_lba)) {
+	case 1: /* Guard tag error */
+		if (scp->prot_flags & SCSI_PROT_GUARD_CHECK) {
+			mk_sense_buffer(scp, ILLEGAL_REQUEST,
+					LOGICAL_BLOCK_GUARD_CHECK_FAILED);
+			*scsi_status = illegal_condition_result;
+			return -1;
+		}
+		if (scp->cmnd[1] >> 5 != 3) { /* WRPROTECT != 3 */
+			mk_sense_buffer(scp, ABORTED_COMMAND,
+					LOGICAL_BLOCK_GUARD_CHECK_FAILED);
+			*scsi_status = check_condition_result;
+			return -1;
+		}
+		break;
+	case 3: /* Reference tag error */
+		if (scp->prot_flags & SCSI_PROT_REF_CHECK) {
+			mk_sense_buffer(scp, ILLEGAL_REQUEST,
+				LOGICAL_BLOCK_REFERENCE_TAG_CHECK_FAILED);
+			*scsi_status = illegal_condition_result;
+			return -1;
+		}
+		if (scp->cmnd[1] >> 5 != 3) { /* WRPROTECT != 3 */
+			mk_sense_buffer(scp, ABORTED_COMMAND,
+				LOGICAL_BLOCK_REFERENCE_TAG_CHECK_FAILED);
+			*scsi_status = check_condition_result;
+			return -1;
+		}
+		break;
+	}
+
+	return 0;
+}
+
+/*
+ * Returns the number of bytes transferred, or -1 with *scsi_status set to a
+ * SCSI status code on failure.
+ */
+static int __resp_write_dt0(struct scsi_cmnd *scp,
+			    struct sdebug_dev_info *devip,
+			    struct sdeb_store_info *sip, u64 lba, u32 num,
+			    u32 ei_lba, u8 group, bool lbp, int *scsi_status)
+{
+	int ret;
+
+	*scsi_status = check_device_access_params(scp, lba, num, true);
+	if (*scsi_status)
+		return -1;
+
+	/* DIX + T10 DIF */
+	if (unlikely(sdebug_dix && scsi_prot_sg_count(scp))) {
+		ret = __resp_write_dt0_dix(scp, lba, num, ei_lba,
+					   scsi_status);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = do_device_access(sip, scp, 0, lba, num, group, true, false);
+	if (ret < 0)
+		*scsi_status = DID_ERROR << 16;
+
+	if (unlikely(lbp))
+		map_region(sip, lba, num);
+
+	/* If ZBC zone then bump its write pointer */
+	if (sdebug_dev_is_zoned(devip) && ret > 0)
+		zbc_inc_wp(devip, lba, ret >> ilog2(sdebug_sector_size));
+
+	return ret;
+}
+
 static int resp_write_dt0(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)
 {
 	bool check_prot;
@@ -5104,7 +5183,7 @@ static int resp_write_dt0(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)
 	u64 lba;
 	struct sdeb_store_info *sip = devip2sip(devip, true);
 	u8 *cmd = scp->cmnd;
-	bool meta_data_locked = false;
+	int scsi_status = DID_ERROR << 16;
 	bool lbp = scsi_debug_lbp();
 
 	if (unlikely(sdebug_opts & SDEBUG_OPT_UNALIGNED_WRITE &&
@@ -5174,60 +5253,16 @@ static int resp_write_dt0(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)
 	if (sdebug_dev_is_zoned(devip) ||
 	    (sdebug_dix && scsi_prot_sg_count(scp)) || lbp) {
 		sdeb_meta_write_lock(sip);
-		meta_data_locked = true;
-	}
-
-	ret = check_device_access_params(scp, lba, num, true);
-	if (ret) {
-		if (meta_data_locked)
-			sdeb_meta_write_unlock(sip);
-		return ret;
-	}
-
-	/* DIX + T10 DIF */
-	if (unlikely(sdebug_dix && scsi_prot_sg_count(scp))) {
-		switch (prot_verify_write(scp, lba, num, ei_lba)) {
-		case 1: /* Guard tag error */
-			if (scp->prot_flags & SCSI_PROT_GUARD_CHECK) {
-				sdeb_meta_write_unlock(sip);
-				mk_sense_buffer(scp, ILLEGAL_REQUEST,
-					LOGICAL_BLOCK_GUARD_CHECK_FAILED);
-				return illegal_condition_result;
-			} else if (scp->cmnd[1] >> 5 != 3) { /* WRPROTECT != 3 */
-				sdeb_meta_write_unlock(sip);
-				mk_sense_buffer(scp, ABORTED_COMMAND,
-					LOGICAL_BLOCK_GUARD_CHECK_FAILED);
-				return check_condition_result;
-			}
-			break;
-		case 3: /* Reference tag error */
-			if (scp->prot_flags & SCSI_PROT_REF_CHECK) {
-				sdeb_meta_write_unlock(sip);
-				mk_sense_buffer(scp, ILLEGAL_REQUEST,
-					LOGICAL_BLOCK_REFERENCE_TAG_CHECK_FAILED);
-				return illegal_condition_result;
-			} else if (scp->cmnd[1] >> 5 != 3) { /* WRPROTECT != 3 */
-				sdeb_meta_write_unlock(sip);
-				mk_sense_buffer(scp, ABORTED_COMMAND,
-					LOGICAL_BLOCK_REFERENCE_TAG_CHECK_FAILED);
-				return check_condition_result;
-			}
-			break;
-		}
-	}
-
-	ret = do_device_access(sip, scp, 0, lba, num, group, true, false);
-	if (unlikely(lbp))
-		map_region(sip, lba, num);
-
-	/* If ZBC zone then bump its write pointer over the data written */
-	if (sdebug_dev_is_zoned(devip) && ret > 0)
-		zbc_inc_wp(devip, lba, ret >> ilog2(sdebug_sector_size));
-	if (meta_data_locked)
+		ret = __resp_write_dt0(scp, devip, sip, lba, num, ei_lba, group,
+				       lbp, &scsi_status);
 		sdeb_meta_write_unlock(sip);
+	} else {
+		ret = __resp_write_dt0(scp, devip, sip, lba, num, ei_lba, group,
+				       lbp, &scsi_status);
+	}
 
 	if (unlikely(-1 == ret))
-		return DID_ERROR << 16;
+		return scsi_status;
 	else if (unlikely(sdebug_verbose &&
 			  (ret < (num * sdebug_sector_size))))
 		sdev_printk(KERN_INFO, scp->device,