diff --git a/dm-compress/dm-compress.c b/dm-compress/dm-compress.c
index 2fb4af6..9f8734f 100644
--- a/dm-compress/dm-compress.c
+++ b/dm-compress/dm-compress.c
@@ -118,71 +118,77 @@ dm_target_pblk_size(struct dm_target* ti)
  * data is a page address (obtained via __get_free_pages and friends).
  **************************************/
 
-static int
-blkdev_pblk_io(struct block_device* dev, unsigned int op, u64 pblk, u32 count, void *data)
+static struct bio*
+blkdev_pblk_io_prepare(struct block_device* dev, unsigned int op, u64 pblk, u32 count, void *data)
 {
-    int ret;
     unsigned long data_addr;
-    struct bio *bio;
+    struct bio* bio;
 
     data_addr = (unsigned long)data;
-
-    if (data_addr & (PAGE_SIZE-1)) {
-        printk(KERN_ERR "  Not page aligned\n");
-        return -EINVAL;
-    }
-
-    if (!virt_addr_valid(data)) {
-        printk(KERN_ERR "  Not valid address\n");
-        return -EINVAL;
-    }
+    BUG_ON(data_addr & (PAGE_SIZE-1));
+    BUG_ON(!virt_addr_valid(data));
 
     bio = bio_alloc(GFP_KERNEL, count);
+    if (!bio) {
+        printk(KERN_ERR "%s: out of memory\n", __func__);
+        return NULL;
+    }
+    bio_set_dev(bio, dev);
+    bio->bi_opf = op;
+
+    bio->bi_iter.bi_sector = (pblk << (PBLK_SHIFT - SECTOR_SHIFT));
+    while (count--) {
+        struct page *page = virt_to_page(data);
+        if (bio_add_page(bio, page, PAGE_SIZE, 0) != PAGE_SIZE) {
+            BUG();
+        }
+        data = (u8*)data + PAGE_SIZE;
+    }
+
+    return bio;
+}
+
+static int
+blkdev_pblk_read(struct block_device* dev, u64 pblk, u32 count, void *data)
+{
+    int ret;
+    struct bio* bio;
+
+    bio = blkdev_pblk_io_prepare(dev, REQ_OP_READ, pblk, count, data);
     if (!bio) {
         printk(KERN_ERR "%s: out of memory\n", __func__);
         return -ENOMEM;
     }
 
-    bio_set_dev(bio, dev);
-    bio->bi_iter.bi_sector = (pblk << (PBLK_SHIFT - SECTOR_SHIFT));
-    bio->bi_opf = op;
-
-    while (count--) {
-        struct page *page = virt_to_page(data);
-        if (bio_add_page(bio, page, PAGE_SIZE, 0) != PAGE_SIZE) {
-            printk(KERN_ERR "%s: cannot add page to bio\n", __func__);
-            bio_put(bio);
-            return -EINVAL;
-        }
-        data = (u8*)data + PAGE_SIZE;
-    }
-
-    /*
-     * XXX: We would like to make writes asychronous, but submit_bio() does
-     * not return a meaningful status.
-     */
     ret = submit_bio_wait(bio);
     if (ret != 0) {
-        printk(KERN_ERR "%s: submit_bio failed\n", __func__);
-        bio_put(bio);
-        return ret;
+        printk(KERN_ERR "%s: submit_bio_wait failed: %d\n", __func__, ret);
     }
-
     bio_put(bio);
 
     return ret;
 }
 
-static int
-blkdev_pblk_read(struct block_device* dev, u64 pblk, u32 count, void *data)
-{
-    return blkdev_pblk_io(dev, REQ_OP_READ, pblk, count, data);
-}
-
 static int
 blkdev_pblk_write(struct block_device* dev, u64 pblk, u32 count, void *data)
 {
-    return blkdev_pblk_io(dev, REQ_OP_WRITE, pblk, count, data);
+    int ret;
+    struct bio* bio;
+
+    bio = blkdev_pblk_io_prepare(dev, REQ_OP_WRITE, pblk, count, data);
+    if (!bio) {
+        printk(KERN_ERR "%s: out of memory\n", __func__);
+        return -ENOMEM;
+    }
+
+    /* XXX: Make writes asychronous. */
+    ret = submit_bio_wait(bio);
+    if (ret != 0) {
+        printk(KERN_ERR "%s: submit_bio_wait failed: %d\n", __func__, ret);
+    }
+    bio_put(bio);
+
+    return ret;
 }
 
 /**************************************