fix: Fix builds with the dm-io non-retryable error interface

src/Makefile

@@ -8,6 +8,9 @@ wb_dm_io_header := $(srctree)/include/linux/dm-io.h
 # added the IO priority parameter in v6.9-rc1.
 # The dm-io ioprio argument is also backported to stable kernels.
 ccflags-y += -DDM_IO_HAS_IOPRIO=$(if $(shell grep -w ioprio $(wb_dm_io_header)),1,0)
+
+# The dm-io unsupported-error bitmap is also backported to stable kernels.
+ccflags-y += -DDM_IO_HAS_UNSUP=$(if $(shell grep -w sync_unsup_bits $(wb_dm_io_header)),1,0)
 endif
 
 obj-m := dm-writeboost.o

src/dm-writeboost-daemon.c

@@ -165,6 +165,7 @@ static void writeback_endio(unsigned long error, void *context)
 	if (atomic_dec_and_test(&wb->writeback_io_count))
 		wake_up(&wb->writeback_io_wait_queue);
 }
+WB_IO_NOTIFY_COMPAT(writeback_endio);
 
 static void submit_writeback_io(struct wb_device *wb, struct writeback_io *writeback_io)
 {
@@ -174,7 +175,7 @@ static void submit_writeback_io(struct wb_device *wb, struct writeback_io *write
 		struct dm_io_request io_req_w = {
 			WB_IO_WRITE,
 			.client = wb->io_client,
-			.notify.fn = writeback_endio,
+			.notify.fn = WB_IO_NOTIFY(writeback_endio),
 			.notify.context = wb,
 			.mem.type = DM_IO_VMA,
 			.mem.ptr.addr = writeback_io->data,
@@ -199,7 +200,7 @@ static void submit_writeback_io(struct wb_device *wb, struct writeback_io *write
 			io_req_w = (struct dm_io_request) {
 				WB_IO_WRITE,
 				.client = wb->io_client,
-				.notify.fn = writeback_endio,
+				.notify.fn = WB_IO_NOTIFY(writeback_endio),
 				.notify.context = wb,
 				.mem.type = DM_IO_VMA,
 				.mem.ptr.addr = writeback_io->data + (i << 9),

src/dm-writeboost-metadata.c

@@ -419,6 +419,7 @@ static void format_segmd_endio(unsigned long error, void *__context)
 		context->err = 1;
 	atomic64_dec(&context->count);
 }
+WB_IO_NOTIFY_COMPAT(format_segmd_endio);
 
 struct zeroing_context {
 	int error;
@@ -479,7 +480,7 @@ static int format_all_segment_headers(struct wb_device *wb)
 		struct dm_io_request io_req_seg = {
 			WB_IO_WRITE,
 			.client = wb->io_client,
-			.notify.fn = format_segmd_endio,
+			.notify.fn = WB_IO_NOTIFY(format_segmd_endio),
 			.notify.context = &context,
 			.mem.type = DM_IO_KMEM,
 			.mem.ptr.addr = buf,

src/dm-writeboost-target.c

@@ -26,7 +26,21 @@
 
 #include "linux/sort.h"
 
-#if DM_IO_HAS_IOPRIO
+#if DM_IO_HAS_UNSUP
+static int dm_io_compat(struct dm_io_request *io_req, unsigned num_regions,
+			struct dm_io_region *regions, unsigned long *error_bits)
+{
+	unsigned long io_error_bits = 0, unsup_bits = 0;
+	int r;
+
+	r = dm_io(io_req, num_regions, regions, &io_error_bits, &unsup_bits,
+		  IOPRIO_DEFAULT);
+	if (error_bits)
+		*error_bits = io_error_bits | unsup_bits;
+	return r;
+}
+#define DM_IO(arg1, arg2, arg3, arg4) dm_io_compat(arg1, arg2, arg3, arg4)
+#elif DM_IO_HAS_IOPRIO
 #define DM_IO(arg1, arg2, arg3, arg4) dm_io(arg1, arg2, arg3, arg4, IOPRIO_DEFAULT)
 #else
 #define DM_IO(arg1, arg2, arg3, arg4) dm_io(arg1, arg2, arg3, arg4)
@@ -1274,6 +1288,7 @@ static void read_backing_async_callback(unsigned long error, void *context)
 	read_backing_async_callback_onstack(error, ctx);
 	kfree(ctx);
 }
+WB_IO_NOTIFY_COMPAT(read_backing_async_callback);
 
 static int read_backing_async(struct wb_device *wb, struct bio *bio)
 {
@@ -1296,7 +1311,7 @@ static int read_backing_async(struct wb_device *wb, struct bio *bio)
 		.client = wb->io_client,
 		.mem.type = DM_IO_BIO,
 		.mem.ptr.bio = bio,
-		.notify.fn = read_backing_async_callback,
+		.notify.fn = WB_IO_NOTIFY(read_backing_async_callback),
 		.notify.context = ctx
 	};
 	region = (struct dm_io_region) {

src/dm-writeboost.h

@@ -37,6 +37,19 @@
 #include <linux/dm-io.h>
 #include <linux/dm-kcopyd.h>
 
+/* Preserve the old combined error bitmap for dm-io completion handlers. */
+#if DM_IO_HAS_UNSUP
+#define WB_IO_NOTIFY(fn) fn##_compat
+#define WB_IO_NOTIFY_COMPAT(fn) \
+static void fn##_compat(unsigned long error, unsigned long unsup, void *context) \
+{ \
+	fn(error | unsup, context); \
+}
+#else
+#define WB_IO_NOTIFY(fn) fn
+#define WB_IO_NOTIFY_COMPAT(fn)
+#endif
+
 /*----------------------------------------------------------------------------*/
 
 #define SUB_ID(x, y) ((x) > (y) ? (x) - (y) : 0)