configure framework: detect make_req_fn type

Signed-off-by: Michal Mielewczyk <michal.mielewczyk@huawei.com>

configure.d/1_make_req_type.conf

@@ -0,0 +1,87 @@
+#!/bin/bash
+#
+# Copyright(c) 2024 Huawei Technologies
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+. $(dirname $3)/conf_framework.sh
+
+check() {
+        cur_name=$(basename $2)
+        config_file_path=$1
+
+
+    # The commit c62b37d96b6eb3ec5 in the kernel repo introduces `submit_bio`
+    # and removes make_request_fn
+    if compile_module $cur_name "struct block_device_operations x; x.submit_bio;" "linux/blkdev.h";
+    then
+            # If it's impossible to cast the return value of submit_bio()
+            # to an int we're assuming the function is of type void.
+            # It's not a generic solution because the check would pass if
+            # the return type would be a struct, but it can't happend in this
+            # specific scenario
+            # Mind the negation in the condition
+            if ! compile_module $cur_name \
+                        "struct block_device_operations x; int y = (int)x.submit_bio(NULL);" "linux/blkdev.h";
+                        then
+                # submit_bio is of type void
+                echo $cur_name "1" >> $config_file_path
+            elif compile_module $cur_name \
+                        "struct block_device_operations x; blk_qc_t y = x.submit_bio(NULL);" "linux/blkdev.h" ;
+            then
+                # submit_bio is of type blk_qc_t
+                echo $cur_name "2" >> $config_file_path
+            else
+                echo $cur_name "X" >> $config_file_path
+            fi
+    else
+            # If it's impossible to cast the return value of make_request_fn()
+            # to an int we're assuming the function is of type void.
+            # It's not a generic solution because the check would pass if
+            # the return type would be a struct, but it can't happend in this
+            # specific scenario
+            # Mind the negation in the condition
+            if ! compile_module $cur_name \
+                        "struct request_queue *q; int y = (int)q->make_request_fn(NULL);" "linux/blkdev.h";
+            then
+                # make_request_fn is of type void
+                echo $cur_name "3" >> $config_file_path
+            elif ! compile_module $cur_name \
+                        "struct request_queue *q; blk_qc_t y = q->make_request_fn(NULL);" "linux/blkdev.h";
+            then
+                # make_request_fn is of type blk_qc_t
+                echo $cur_name "4" >> $config_file_path
+            elif ! compile_module $cur_name \
+                        "struct request_queue *q; int y = q->make_request_fn(NULL);" "linux/blkdev.h";
+            then
+                # make_request_fn is of type int
+                echo $cur_name "5" >> $config_file_path
+            else
+                echo $cur_name "X" >> $config_file_path
+            fi
+    fi
+}
+
+apply() {
+    case "$1" in
+    "1")
+        add_define "CAS_KRETURN(_x) return "
+        add_define "CAS_MAKE_REQ_RET_TYPE void " ;;
+    "2")
+        add_define "CAS_KRETURN(_x) ({ return (_x); }) "
+        add_define "CAS_MAKE_REQ_RET_TYPE blk_qc_t " ;;
+    "3")
+        add_define "CAS_KRETURN(_x) return "
+        add_define "CAS_MAKE_REQ_RET_TYPE void " ;;
+    "4")
+        add_define "CAS_KRETURN(_x) ({ return (_x); }) "
+        add_define "CAS_MAKE_REQ_RET_TYPE blk_qc_t " ;;
+    "5")
+        add_define "CAS_KRETURN(_x) ({ return (_x); }) "
+        add_define "CAS_MAKE_REQ_RET_TYPE int " ;;
+    *)
+        exit 1
+    esac
+}
+
+conf_run $@

modules/cas_cache/exp_obj.c

@@ -31,27 +31,6 @@ static inline void bd_release_from_disk(struct block_device *bdev,
 	return bd_unlink_disk_holder(bdev, disk);
 }
 
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 18, 0)
-       #define KRETURN(x)      return
-       #define MAKE_RQ_RET_TYPE void
-#elif LINUX_VERSION_CODE >= KERNEL_VERSION(4, 3, 0)
-       #define KRETURN(x)      ({ return (x); })
-       #define MAKE_RQ_RET_TYPE blk_qc_t
-#else
-       #define KRETURN(x)      return
-       #define MAKE_RQ_RET_TYPE void
-#endif
-
-/* For RHEL 9.x we assume backport from kernel 5.18+ */
-#ifdef RHEL_MAJOR
-	#if RHEL_MAJOR >= 9
-		#undef KRETURN
-		#undef MAKE_RQ_RET_TYPE
-		#define KRETURN(x)      return
-		#define MAKE_RQ_RET_TYPE void
-	#endif
-#endif
-
 int __init cas_init_exp_objs(void)
 {
 	CAS_DEBUG_TRACE();
@@ -82,7 +61,7 @@ void cas_deinit_exp_objs(void)
 	unregister_blkdev(cas_module.disk_major, "cas");
 }
 
-static MAKE_RQ_RET_TYPE _cas_exp_obj_submit_bio(struct bio *bio)
+static CAS_MAKE_REQ_RET_TYPE _cas_exp_obj_submit_bio(struct bio *bio)
 {
 	struct cas_disk *dsk;
 	struct cas_exp_obj *exp_obj;
@@ -93,15 +72,15 @@ static MAKE_RQ_RET_TYPE _cas_exp_obj_submit_bio(struct bio *bio)
 
 	exp_obj->ops->submit_bio(dsk, bio, exp_obj->private);
 
-	KRETURN(0);
+	CAS_KRETURN(0);
 }
 
-static MAKE_RQ_RET_TYPE _cas_exp_obj_make_rq_fn(struct request_queue *q,
+static CAS_MAKE_REQ_RET_TYPE _cas_exp_obj_make_rq_fn(struct request_queue *q,
 						 struct bio *bio)
 {
 	_cas_exp_obj_submit_bio(bio);
 	cas_blk_queue_exit(q);
-	KRETURN(0);
+	CAS_KRETURN(0);
 }
 
 static int _cas_del_partitions(struct cas_disk *dsk)