diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index ad72741..2436163 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -124,8 +124,7 @@
 	u32 csum;
 	u32 *cb_sum = &cb->sums;
 
-	if (btrfs_test_opt(root, NODATASUM) ||
-	    btrfs_test_flag(inode, NODATASUM))
+	if (btrfs_test_flag(inode, NODATASUM))
 		return 0;
 
 	for (i = 0; i < cb->nr_pages; i++) {
@@ -671,8 +670,7 @@
 			 */
 			atomic_inc(&cb->pending_bios);
 
-			if (!btrfs_test_opt(root, NODATASUM) &&
-			    !btrfs_test_flag(inode, NODATASUM)) {
+			if (!btrfs_test_flag(inode, NODATASUM)) {
 				btrfs_lookup_bio_sums(root, inode, comp_bio,
 						      sums);
 			}
@@ -699,8 +697,7 @@
 	ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
 	BUG_ON(ret);
 
-	if (!btrfs_test_opt(root, NODATASUM) &&
-	    !btrfs_test_flag(inode, NODATASUM)) {
+	if (!btrfs_test_flag(inode, NODATASUM)) {
 		btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
 	}
 
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 8733081..b89999de 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1702,7 +1702,7 @@
 int btrfs_drop_leaf_ref(struct btrfs_trans_handle *trans,
 			struct btrfs_root *root, struct extent_buffer *leaf);
 int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,
-			  struct btrfs_root *root, u64 bytenr);
+			  struct btrfs_root *root, u64 objectid, u64 bytenr);
 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
 			 struct btrfs_root *root);
 int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy);
@@ -1789,6 +1789,7 @@
 			       struct extent_buffer *buf, u64 orig_start);
 int btrfs_add_dead_reloc_root(struct btrfs_root *root);
 int btrfs_cleanup_reloc_trees(struct btrfs_root *root);
+int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len);
 u64 btrfs_reduce_alloc_profile(struct btrfs_root *root, u64 flags);
 /* ctree.c */
 int btrfs_previous_item(struct btrfs_root *root,
@@ -1994,6 +1995,8 @@
 int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
 			struct btrfs_root *root, struct btrfs_path *path,
 			u64 isize);
+int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start,
+			     u64 end, struct list_head *list);
 /* inode.c */
 
 /* RHEL and EL kernels have a patch that renames PG_checked to FsMisc */
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 171057a..8004695 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1359,7 +1359,7 @@
 }
 
 int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,
-			  struct btrfs_root *root, u64 bytenr)
+			  struct btrfs_root *root, u64 objectid, u64 bytenr)
 {
 	struct btrfs_root *extent_root = root->fs_info->extent_root;
 	struct btrfs_path *path;
@@ -1418,8 +1418,9 @@
 		ref_item = btrfs_item_ptr(leaf, path->slots[0],
 					  struct btrfs_extent_ref);
 		ref_root = btrfs_ref_root(leaf, ref_item);
-		if (ref_root != root->root_key.objectid &&
-		    ref_root != BTRFS_TREE_LOG_OBJECTID) {
+		if ((ref_root != root->root_key.objectid &&
+		     ref_root != BTRFS_TREE_LOG_OBJECTID) ||
+		     objectid != btrfs_ref_objectid(leaf, ref_item)) {
 			ret = 1;
 			goto out;
 		}
@@ -5367,7 +5368,6 @@
 				if (ret)
 					goto out;
 			}
-			btrfs_record_root_in_trans(found_root);
 			ret = replace_one_extent(trans, found_root,
 						path, extent_key,
 						&first_key, ref_path,
@@ -5534,6 +5534,7 @@
 	} else {
 		BUG_ON(1);
 	}
+	BTRFS_I(inode)->index_cnt = group->key.objectid;
 
 	err = btrfs_orphan_add(trans, inode);
 out:
@@ -5546,6 +5547,47 @@
 	return inode;
 }
 
+int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
+{
+
+	struct btrfs_ordered_sum *sums;
+	struct btrfs_sector_sum *sector_sum;
+	struct btrfs_ordered_extent *ordered;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct list_head list;
+	size_t offset;
+	int ret;
+	u64 disk_bytenr;
+
+	INIT_LIST_HEAD(&list);
+
+	ordered = btrfs_lookup_ordered_extent(inode, file_pos);
+	BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
+
+	disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
+	ret = btrfs_lookup_csums_range(root, disk_bytenr,
+				       disk_bytenr + len - 1, &list);
+
+	while (!list_empty(&list)) {
+		sums = list_entry(list.next, struct btrfs_ordered_sum, list);
+		list_del_init(&sums->list);
+
+		sector_sum = sums->sums;
+		sums->bytenr = ordered->start;
+
+		offset = 0;
+		while (offset < sums->len) {
+			sector_sum->bytenr += ordered->start - disk_bytenr;
+			sector_sum++;
+			offset += root->sectorsize;
+		}
+
+		btrfs_add_ordered_sum(inode, ordered, sums);
+	}
+	btrfs_put_ordered_extent(ordered);
+	return 0;
+}
+
 int btrfs_relocate_block_group(struct btrfs_root *root, u64 group_start)
 {
 	struct btrfs_trans_handle *trans;
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 2d5f670..c5b483a 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -16,6 +16,7 @@
 #define EXTENT_ORDERED (1 << 9)
 #define EXTENT_ORDERED_METADATA (1 << 10)
 #define EXTENT_BOUNDARY (1 << 11)
+#define EXTENT_NODATASUM (1 << 12)
 #define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK)
 
 /* flags for bio submission */
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 3ebef87..df04476 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -140,6 +140,7 @@
 	return ret;
 }
 
+
 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
 			  struct bio *bio, u32 *dst)
 {
@@ -185,9 +186,16 @@
 				if (ret == -ENOENT || ret == -EFBIG)
 					ret = 0;
 				sum = 0;
-				printk("no csum found for inode %lu start "
-				       "%llu\n", inode->i_ino,
-				       (unsigned long long)offset);
+				if (BTRFS_I(inode)->root->root_key.objectid ==
+				    BTRFS_DATA_RELOC_TREE_OBJECTID) {
+					set_extent_bits(io_tree, offset,
+						offset + bvec->bv_len - 1,
+						EXTENT_NODATASUM, GFP_NOFS);
+				} else {
+					printk("no csum found for inode %lu "
+					       "start %llu\n", inode->i_ino,
+					       (unsigned long long)offset);
+				}
 				item = NULL;
 				btrfs_release_path(root, path);
 				goto found;
@@ -228,6 +236,106 @@
 	return 0;
 }
 
+int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
+			     struct list_head *list)
+{
+	struct btrfs_key key;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_ordered_sum *sums;
+	struct btrfs_sector_sum *sector_sum;
+	struct btrfs_csum_item *item;
+	unsigned long offset;
+	int ret;
+	size_t size;
+	u64 csum_end;
+	u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
+
+	path = btrfs_alloc_path();
+	BUG_ON(!path);
+
+	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+	key.offset = start;
+	key.type = BTRFS_EXTENT_CSUM_KEY;
+
+	ret = btrfs_search_slot(NULL, root->fs_info->csum_root,
+				&key, path, 0, 0);
+	if (ret < 0)
+		goto fail;
+	if (ret > 0 && path->slots[0] > 0) {
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
+		if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
+		    key.type == BTRFS_EXTENT_CSUM_KEY) {
+			offset = (start - key.offset) >>
+				 root->fs_info->sb->s_blocksize_bits;
+			if (offset * csum_size <
+			    btrfs_item_size_nr(leaf, path->slots[0] - 1))
+				path->slots[0]--;
+		}
+	}
+
+	while (start <= end) {
+		leaf = path->nodes[0];
+		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root->fs_info->csum_root, path);
+			if (ret < 0)
+				goto fail;
+			if (ret > 0)
+				break;
+			leaf = path->nodes[0];
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
+		    key.type != BTRFS_EXTENT_CSUM_KEY)
+			break;
+
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+		if (key.offset > end)
+			break;
+
+		if (key.offset > start)
+			start = key.offset;
+
+		size = btrfs_item_size_nr(leaf, path->slots[0]);
+		csum_end = key.offset + (size / csum_size) * root->sectorsize;
+
+		size = min(csum_end, end + 1) - start;
+		sums = kzalloc(btrfs_ordered_sum_size(root, size), GFP_NOFS);
+		BUG_ON(!sums);
+
+		sector_sum = sums->sums;
+		sums->bytenr = start;
+		sums->len = size;
+
+		offset = (start - key.offset) >>
+			 root->fs_info->sb->s_blocksize_bits;
+		offset *= csum_size;
+
+		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+				      struct btrfs_csum_item);
+		while (size > 0) {
+			read_extent_buffer(path->nodes[0], &sector_sum->sum,
+					   ((unsigned long)item) + offset,
+					   csum_size);
+			sector_sum->bytenr = start;
+
+			size -= root->sectorsize;
+			start += root->sectorsize;
+			offset += csum_size;
+			sector_sum++;
+		}
+		list_add_tail(&sums->list, list);
+
+		path->slots[0]++;
+	}
+	ret = 0;
+fail:
+	btrfs_free_path(path);
+	return ret;
+}
+
 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
 		       struct bio *bio, u64 file_start, int contig)
 {
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 71bfe3a..5070810 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1060,14 +1060,6 @@
 	last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 
 	/*
-	 * if this is a nodatasum mount, force summing off for the inode
-	 * all the time.  That way a later mount with summing on won't
-	 * get confused
-	 */
-	if (btrfs_test_opt(root, NODATASUM))
-		btrfs_set_flag(inode, NODATASUM);
-
-	/*
 	 * there are lots of better ways to do this, but this code
 	 * makes sure the first and last page in the file range are
 	 * up to date and ready for cow
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 0a28b77..e64a4fe 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -771,6 +771,13 @@
 					       ram_size, cur_alloc_size, 0);
 		BUG_ON(ret);
 
+		if (root->root_key.objectid ==
+		    BTRFS_DATA_RELOC_TREE_OBJECTID) {
+			ret = btrfs_reloc_clone_csums(inode, start,
+						      cur_alloc_size);
+			BUG_ON(ret);
+		}
+
 		if (disk_num_bytes < cur_alloc_size) {
 			printk("num_bytes %Lu cur_alloc %Lu\n", disk_num_bytes,
 			       cur_alloc_size);
@@ -910,6 +917,26 @@
 	return 0;
 }
 
+static int noinline csum_exist_in_range(struct btrfs_root *root,
+					u64 bytenr, u64 num_bytes)
+{
+	int ret;
+	struct btrfs_ordered_sum *sums;
+	LIST_HEAD(list);
+
+	ret = btrfs_lookup_csums_range(root, bytenr, bytenr + num_bytes - 1,
+				       &list);
+	if (ret == 0 && list_empty(&list))
+		return 0;
+
+	while (!list_empty(&list)) {
+		sums = list_entry(list.next, struct btrfs_ordered_sum, list);
+		list_del(&sums->list);
+		kfree(sums);
+	}
+	return 1;
+}
+
 /*
  * when nowcow writeback call back.  This checks for snapshots or COW copies
  * of the extents that exist in the file, and COWs the file as required.
@@ -971,6 +998,7 @@
 
 		nocow = 0;
 		disk_bytenr = 0;
+		num_bytes = 0;
 		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 
 		if (found_key.objectid > inode->i_ino ||
@@ -996,19 +1024,29 @@
 				path->slots[0]++;
 				goto next_slot;
 			}
+			if (disk_bytenr == 0)
+				goto out_check;
 			if (btrfs_file_extent_compression(leaf, fi) ||
 			    btrfs_file_extent_encryption(leaf, fi) ||
 			    btrfs_file_extent_other_encoding(leaf, fi))
 				goto out_check;
-			if (disk_bytenr == 0)
-				goto out_check;
 			if (extent_type == BTRFS_FILE_EXTENT_REG && !force)
 				goto out_check;
-			if (btrfs_cross_ref_exist(trans, root, disk_bytenr))
-				goto out_check;
 			if (btrfs_extent_readonly(root, disk_bytenr))
 				goto out_check;
+			if (btrfs_cross_ref_exist(trans, root, inode->i_ino,
+						  disk_bytenr))
+				goto out_check;
 			disk_bytenr += btrfs_file_extent_offset(leaf, fi);
+			disk_bytenr += cur_offset - found_key.offset;
+			num_bytes = min(end + 1, extent_end) - cur_offset;
+			/*
+			 * force cow if csum exists in the range.
+			 * this ensure that csum for a given extent are
+			 * either valid or do not exist.
+			 */
+			if (csum_exist_in_range(root, disk_bytenr, num_bytes))
+				goto out_check;
 			nocow = 1;
 		} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 			extent_end = found_key.offset +
@@ -1041,8 +1079,6 @@
 			cow_start = (u64)-1;
 		}
 
-		disk_bytenr += cur_offset - found_key.offset;
-		num_bytes = min(end + 1, extent_end) - cur_offset;
 		if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
 			struct extent_map *em;
 			struct extent_map_tree *em_tree;
@@ -1105,11 +1141,9 @@
 			      u64 start, u64 end, int *page_started,
 			      unsigned long *nr_written)
 {
-	struct btrfs_root *root = BTRFS_I(inode)->root;
 	int ret;
 
-	if (btrfs_test_opt(root, NODATACOW) ||
-	    btrfs_test_flag(inode, NODATACOW))
+	if (btrfs_test_flag(inode, NODATACOW))
 		ret = run_delalloc_nocow(inode, locked_page, start, end,
                                         page_started, 1, nr_written);
 	else if (btrfs_test_flag(inode, PREALLOC))
@@ -1252,8 +1286,7 @@
 	ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
 	BUG_ON(ret);
 
-	skip_sum = btrfs_test_opt(root, NODATASUM) ||
-		btrfs_test_flag(inode, NODATASUM);
+	skip_sum = btrfs_test_flag(inode, NODATASUM);
 
 	if (!(rw & (1 << BIO_RW))) {
 		if (bio_flags & EXTENT_BIO_COMPRESSED) {
@@ -1263,6 +1296,9 @@
 			btrfs_lookup_bio_sums(root, inode, bio, NULL);
 		goto mapit;
 	} else if (!skip_sum) {
+		/* csum items have already been cloned */
+		if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
+			goto mapit;
 		/* we're doing a write, do the async checksumming */
 		return btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info,
 				   inode, rw, bio, mirror_num,
@@ -1692,10 +1728,16 @@
 		ClearPageChecked(page);
 		goto good;
 	}
-	if (btrfs_test_opt(root, NODATASUM) ||
-	    btrfs_test_flag(inode, NODATASUM))
+	if (btrfs_test_flag(inode, NODATASUM))
 		return 0;
 
+	if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID &&
+	    test_range_bit(io_tree, start, end, EXTENT_NODATASUM, 1)) {
+		clear_extent_bits(io_tree, start, end, EXTENT_NODATASUM,
+				  GFP_NOFS);
+		return 0;
+	}
+
 	if (state && state->start == start) {
 		private = state->private;
 		ret = 0;
@@ -3391,6 +3433,12 @@
 		owner = 1;
 	BTRFS_I(inode)->block_group =
 			btrfs_find_block_group(root, 0, alloc_hint, owner);
+	if ((mode & S_IFREG)) {
+		if (btrfs_test_opt(root, NODATASUM))
+			btrfs_set_flag(inode, NODATASUM);
+		if (btrfs_test_opt(root, NODATACOW))
+			btrfs_set_flag(inode, NODATACOW);
+	}
 
 	key[0].objectid = objectid;
 	btrfs_set_key_type(&key[0], BTRFS_INODE_ITEM_KEY);