kver ?= $(shell uname -r)

srctree ?= /lib/modules/$(kver)/build
srcroot = $(shell pwd)

SNAPAPI_FLAGS := $(shell \
	grep -q freeze_bdev $(srctree)/include/linux/buffer_head.h \
	$(srctree)/include/linux/fs.h && \
		echo -DHAVE_FREEZE_BDEV)
ifeq ($(notdir $(wildcard $(srctree)/include/linux/config.h)),config.h)
	SNAPAPI_FLAGS += -DHAVE_LINUX_CONFIG
endif
ifeq ($(notdir $(wildcard $(srctree)/include/linux/autoconf.h)),autoconf.h)
	SNAPAPI_FLAGS += -DHAVE_LINUX_AUTOCONF
endif
ifeq ($(notdir $(wildcard $(srctree)/include/generated/autoconf.h)),autoconf.h)
	SNAPAPI_FLAGS += -DHAVE_GENERATED_AUTOCONF
endif
ifeq ($(notdir $(wildcard $(srctree)/include/linux/ioctl32.h)),ioctl32.h)
	SNAPAPI_FLAGS += -DHAVE_IOCTL32_CONVERSIONS
endif
SNAPAPI_FLAGS += $(shell \
	grep -q page_mapcount $(srctree)/include/linux/mm.h && \
		echo -DHAVE_PAGE_MAPCOUNT)
SNAPAPI_FLAGS += $(shell \
	grep -qw SPIN_LOCK_UNLOCKED $(srctree)/include/linux/spinlock_types.h \
	$(srctree)/include/linux/spinlock.h && \
		echo -DHAVE_SPIN_LOCK_UNLOCKED)
SNAPAPI_FLAGS += $(shell \
	grep -qw queue_max_sectors $(srctree)/include/linux/blkdev.h && \
		echo -DHAVE_QUEUE_MAX_SECTORS)
SNAPAPI_FLAGS += $(shell \
	grep -qw fmode_t $(srctree)/include/linux/types.h && \
		echo -DHAVE_FMODE_T)
SNAPAPI_FLAGS += $(shell 							\
	if grep -q try_to_freeze $(srctree)/include/linux/freezer.h; then	\
	     echo -DHAVE_TRY_TO_FREEZE_NO_ARGS -DHAVE_FREEZER_H;			\
	elif grep -qw "try_to_freeze(unsigned.*)" $(srctree)/include/linux/sched.h; then 	\
	     echo -DHAVE_TRY_TO_FREEZE_ONE_ARG;						\
	elif grep -qw "try_to_freeze(void)" $(srctree)/include/linux/sched.h; then 	\
	     echo -DHAVE_TRY_TO_FREEZE_NO_ARGS;						\
	fi)
SNAPAPI_FLAGS += $(shell \
	grep -qw REQ_WRITE $(srctree)/include/linux/fs.h && \
		echo -DHAVE_REQ_WRITE)
SNAPAPI_FLAGS += $(shell \
	grep -qw unlocked_ioctl $(srctree)/include/linux/fs.h && \
		echo -DHAVE_UNLOCKED_IOCTL)
SNAPAPI_FLAGS += $(shell \
	grep -qw "extern int bd_claim" $(srctree)/include/linux/fs.h && \
		echo -DHAVE_BD_CLAIM)
SNAPAPI_FLAGS += $(shell \
	if grep -qw "extern int blkdev_put.*,.*" $(srctree)/include/linux/fs.h; then \
		echo -DHAVE_BLKDEV_PUT_2ARGS; \
		echo -DHAVE_BLKDEV_PUT_INT; \
	elif grep -qw "extern void blkdev_put.*,.*" $(srctree)/include/linux/fs.h; then \
		echo -DHAVE_BLKDEV_PUT_2ARGS; \
		echo -DHAVE_BLKDEV_PUT_VOID; \
	fi)
SNAPAPI_FLAGS += $(shell \
	if grep -qw "extern int blkdev_get.*,.*,.*unsigned.*" $(srctree)/include/linux/fs.h; then \
		echo -DHAVE_BLKDEV_GET_3ARG_FLAG;						\
	elif grep -qw "extern int blkdev_get.*,.*,.*" $(srctree)/include/linux/fs.h; then	\
		echo -DHAVE_BLKDEV_GET_3ARGS;							\
	fi)
SNAPAPI_FLAGS += $(shell \
	if grep -qw "kmap_atomic(.*page.*,.*)" $(srctree)/include/linux/highmem.h; then \
		echo -DHAVE_KMAP_ATOMIC_2ARGS;						\
	fi)
SNAPAPI_FLAGS += $(shell \
	if grep -qw "nr_rqs.*" $(srctree)/include/linux/blkdev.h; then \
		echo -DHAVE_REQUEST_QUEUE_RQS;						\
	fi)
SNAPAPI_FLAGS += $(shell \
	grep -qw "typedef int (make_request_fn)" $(srctree)/include/linux/blkdev.h && \
		echo -DHAVE_MAKE_REQUEST_INT)
SNAPAPI_FLAGS += $(shell \
grep -qw "struct bvec_iter" $(srctree)/include/linux/blk_types.h && \
	echo -DHAVE_BVEC_ITER)

EXTRA_CFLAGS += $(SNAPAPI_FLAGS)

obj-m				+= snapapi26.o
obj-m				+= snumbd26.o

all:
	$(MAKE) -C $(srctree) SUBDIRS=$(srcroot)  modules

clean:
	rm -rf *.mod.? *.ko .*.cmd Module.symvers *.ko.unsigned .tmp_versions