Restore <5.15 kernels support

vdo/bio.c

@@ -23,10 +23,24 @@ void vdo_bio_copy_data_in(struct bio *bio, char *data_ptr)
 	struct bio_vec biovec;
 	struct bvec_iter iter;
 
+// XXX workaround for LINUX_VERSION_CODE < KERNEL_VERSION(5,15,0)
+#ifdef __LINUX_BVEC_ITER_H
+	unsigned long flags;
+
+	bio_for_each_segment(biovec, bio, iter) {
+		void *from = bvec_kmap_irq(&biovec, &flags);
+
+		memcpy(data_ptr, from, biovec.bv_len);
+		data_ptr += biovec.bv_len;
+		bvec_kunmap_irq(from, &flags);
+	}
+#else
+
 	bio_for_each_segment(biovec, bio, iter) {
 		memcpy_from_bvec(data_ptr, &biovec);
 		data_ptr += biovec.bv_len;
 	}
+#endif
 }
 
 /*
@@ -36,11 +50,25 @@ void vdo_bio_copy_data_out(struct bio *bio, char *data_ptr)
 {
 	struct bio_vec biovec;
 	struct bvec_iter iter;
+// XXX workaround for LINUX_VERSION_CODE < KERNEL_VERSION(5,15,0)
+#ifdef __LINUX_BVEC_ITER_H
+	unsigned long flags;
+
+	bio_for_each_segment(biovec, bio, iter) {
+		void *dest = bvec_kmap_irq(&biovec, &flags);
+
+		memcpy(dest, data_ptr, biovec.bv_len);
+		data_ptr += biovec.bv_len;
+		flush_dcache_page(biovec.bv_page);
+		bvec_kunmap_irq(dest, &flags);
+	}
+#else
 
 	bio_for_each_segment(biovec, bio, iter) {
 		memcpy_to_bvec(&biovec, data_ptr);
 		data_ptr += biovec.bv_len;
 	}
+#endif
 }
 
 void vdo_free_bio(struct bio *bio)

vdo/dm-vdo-target.c

@@ -158,13 +158,16 @@ static void vdo_status(struct dm_target *ti,
 		device_config = (struct device_config *) ti->private;
 		DMEMIT("%s", device_config->original_string);
 		break;
+// XXX workaround for LINUX_VERSION_CODE >= KERNEL_VERSION(5,15,0)
+#ifndef __LINUX_BVEC_ITER_H
 	/*
 	 * FIXME: We ought to print more detailed output here, but this is what
 	 * thin does.
 	 */
 	case STATUSTYPE_IMA:
 		*result = '\0';
 		break;
+#endif // 5.15+
 	}
 }
 

vdo/num-utils.h

@@ -13,6 +13,5 @@
 #include "types.h"
 
 #include <linux/log2.h>
-#include <linux/math.h>
 
 #endif /* NUM_UTILS_H */

vdo/vio.h

@@ -18,7 +18,7 @@
 #include "vdo.h"
 
 enum {
-	MAX_BLOCKS_PER_VIO = (BIO_MAX_VECS << PAGE_SHIFT) / VDO_BLOCK_SIZE,
+	MAX_BLOCKS_PER_VIO = (BIO_MAX_PAGES << PAGE_SHIFT) / VDO_BLOCK_SIZE,
 };
 
 /*