diff --git a/drivers/mmc/host/at91_mci.c b/drivers/mmc/host/at91_mci.c
index a6dd7da..336d9f5 100644
--- a/drivers/mmc/host/at91_mci.c
+++ b/drivers/mmc/host/at91_mci.c
@@ -314,8 +314,8 @@
 			dmabuf = (unsigned *)tmpv;
 		}
 
+		flush_kernel_dcache_page(sg_page(sg));
 		kunmap_atomic(sgbuffer, KM_BIO_SRC_IRQ);
-		dmac_flush_range((void *)sgbuffer, ((void *)sgbuffer) + amount);
 		data->bytes_xfered += amount;
 		if (size == 0)
 			break;
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index e84ef60..97a9783 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1481,12 +1481,17 @@
 		ret = -EBADF;
 		goto out_drop_write;
 	}
+
 	src = src_file->f_dentry->d_inode;
 
 	ret = -EINVAL;
 	if (src == inode)
 		goto out_fput;
 
+	/* the src must be open for reading */
+	if (!(src_file->f_mode & FMODE_READ))
+		goto out_fput;
+
 	ret = -EISDIR;
 	if (S_ISDIR(src->i_mode) || S_ISDIR(inode->i_mode))
 		goto out_fput;
diff --git a/lib/btree.c b/lib/btree.c
index 41859a8..c9c6f03 100644
--- a/lib/btree.c
+++ b/lib/btree.c
@@ -95,7 +95,8 @@
 	unsigned long *node;
 
 	node = mempool_alloc(head->mempool, gfp);
-	memset(node, 0, NODESIZE);
+	if (likely(node))
+		memset(node, 0, NODESIZE);
 	return node;
 }