diff --git a/kmod/src/Makefile.kernelcompat b/kmod/src/Makefile.kernelcompat
index e8d23274..c99e046d 100644
--- a/kmod/src/Makefile.kernelcompat
+++ b/kmod/src/Makefile.kernelcompat
@@ -501,3 +501,11 @@ endif
 ifneq (,$(shell grep 'struct shrinker .shrinker_alloc' include/linux/shrinker.h))
 ccflags-y += -DKC_SHRINKER_ALLOC
 endif
+
+#
+# v6.9-rc4-8-gead083aeeed9
+#
+# set_blocksize() now has a struct file arg.
+ifneq (,$(shell grep -s 'int set_blocksize.struct file' include/linux/blkdev.h))
+ccflags-y += -DKC_BLKDEV_SET_BLOCKSIZE_FILE
+endif
diff --git a/kmod/src/super.c b/kmod/src/super.c
index 51801718..2d806568 100644
--- a/kmod/src/super.c
+++ b/kmod/src/super.c
@@ -552,6 +552,7 @@ static int scoutfs_fill_super(struct super_block *sb, void *data, int silent)
 	}
 	sbi->meta_bdev_file = meta_bdev_file;
 	sbi->meta_bdev = file_bdev(meta_bdev_file);
+
 #else
 #ifdef KC_BLKDEV_PUT_HOLDER_ARG
 	meta_bdev = blkdev_get_by_path(opts.metadev_path, SCOUTFS_META_BDEV_MODE, sb, NULL);
@@ -567,7 +568,11 @@ static int scoutfs_fill_super(struct super_block *sb, void *data, int silent)
 	sbi->meta_bdev = meta_bdev;
 #endif
 
+#ifdef KC_BLKDEV_SET_BLOCKSIZE_FILE
+	ret = set_blocksize(sbi->meta_bdev_file, SCOUTFS_BLOCK_SM_SIZE);
+#else
 	ret = set_blocksize(sbi->meta_bdev, SCOUTFS_BLOCK_SM_SIZE);
+#endif
 	if (ret != 0) {
 		scoutfs_err(sb, "failed to set metadev blocksize, returned %d",
 			    ret);