diff --git a/Makefile b/Makefile
index b9cfc4d3..dfc116c7 100644
--- a/Makefile
+++ b/Makefile
@@ -113,7 +113,7 @@ cmds_objects = cmds-subvolume.o cmds-filesystem.o cmds-device.o cmds-scrub.o \
 	       cmds-restore.o cmds-rescue.o chunk-recover.o super-recover.o \
 	       cmds-property.o cmds-fi-usage.o cmds-inspect-dump-tree.o \
 	       cmds-inspect-dump-super.o cmds-inspect-tree-stats.o cmds-fi-du.o \
-	       mkfs/common.o
+	       mkfs/common.o check/common.o
 libbtrfs_objects = send-stream.o send-utils.o kernel-lib/rbtree.o btrfs-list.o \
 		   kernel-lib/crc32c.o messages.o \
 		   uuid-tree.o utils-lib.o rbtree-utils.o
diff --git a/check/common.c b/check/common.c
new file mode 100644
index 00000000..ed4f2a40
--- /dev/null
+++ b/check/common.c
@@ -0,0 +1,101 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include "ctree.h"
+#include "internal.h"
+#include "check/common.h"
+
+/*
+ * Search in csum tree to find how many bytes of range [@start, @start + @len)
+ * has the corresponding csum item.
+ *
+ * @start:	range start
+ * @len:	range length
+ * @found:	return value of found csum bytes
+ *		unit is BYTE.
+ */
+int count_csum_range(struct btrfs_fs_info *fs_info, u64 start,
+		     u64 len, u64 *found)
+{
+	struct btrfs_key key;
+	struct btrfs_path path;
+	struct extent_buffer *leaf;
+	int ret;
+	size_t size;
+	*found = 0;
+	u64 csum_end;
+	u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
+
+	btrfs_init_path(&path);
+
+	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+	key.offset = start;
+	key.type = BTRFS_EXTENT_CSUM_KEY;
+
+	ret = btrfs_search_slot(NULL, fs_info->csum_root,
+				&key, &path, 0, 0);
+	if (ret < 0)
+		goto out;
+	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)
+			path.slots[0]--;
+	}
+
+	while (len > 0) {
+		leaf = path.nodes[0];
+		if (path.slots[0] >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(fs_info->csum_root, &path);
+			if (ret > 0)
+				break;
+			else if (ret < 0)
+				goto out;
+			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 >= start + len)
+			break;
+
+		if (key.offset > start)
+			start = key.offset;
+
+		size = btrfs_item_size_nr(leaf, path.slots[0]);
+		csum_end = key.offset + (size / csum_size) *
+			   fs_info->sectorsize;
+		if (csum_end > start) {
+			size = min(csum_end - start, len);
+			len -= size;
+			start += size;
+			*found += size;
+		}
+
+		path.slots[0]++;
+	}
+out:
+	btrfs_release_path(&path);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
diff --git a/check/common.h b/check/common.h
index 77a0ab54..cd64798f 100644
--- a/check/common.h
+++ b/check/common.h
@@ -80,4 +80,7 @@ static inline int fs_root_objectid(u64 objectid)
 	return is_fstree(objectid);
 }
 
+int count_csum_range(struct btrfs_fs_info *fs_info, u64 start,
+		     u64 len, u64 *found);
+
 #endif
diff --git a/check/main.c b/check/main.c
index 04dd06d0..4e7ff2f5 100644
--- a/check/main.c
+++ b/check/main.c
@@ -1424,78 +1424,6 @@ static int process_inode_extref(struct extent_buffer *eb,
 
 }
 
-static int count_csum_range(struct btrfs_root *root, u64 start,
-			    u64 len, u64 *found)
-{
-	struct btrfs_key key;
-	struct btrfs_path path;
-	struct extent_buffer *leaf;
-	int ret;
-	size_t size;
-	*found = 0;
-	u64 csum_end;
-	u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
-
-	btrfs_init_path(&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 out;
-	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)
-			path.slots[0]--;
-	}
-
-	while (len > 0) {
-		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)
-				break;
-			else if (ret < 0)
-				goto out;
-			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 >= start + len)
-			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->fs_info->sectorsize;
-		if (csum_end > start) {
-			size = min(csum_end - start, len);
-			len -= size;
-			start += size;
-			*found += size;
-		}
-
-		path.slots[0]++;
-	}
-out:
-	btrfs_release_path(&path);
-	if (ret < 0)
-		return ret;
-	return 0;
-}
-
 static int process_file_extent(struct btrfs_root *root,
 				struct extent_buffer *eb,
 				int slot, struct btrfs_key *key,
@@ -1575,7 +1503,8 @@ static int process_file_extent(struct btrfs_root *root,
 		else
 			disk_bytenr += extent_offset;
 
-		ret = count_csum_range(root, disk_bytenr, num_bytes, &found);
+		ret = count_csum_range(root->fs_info, disk_bytenr, num_bytes,
+				       &found);
 		if (ret < 0)
 			return ret;
 		if (extent_type == BTRFS_FILE_EXTENT_REG) {
@@ -5508,7 +5437,7 @@ static int check_file_extent(struct btrfs_root *root, struct btrfs_key *fkey,
 		search_start = disk_bytenr;
 		search_len = disk_num_bytes;
 	}
-	ret = count_csum_range(root, search_start, search_len, &csum_found);
+	ret = count_csum_range(root->fs_info, search_start, search_len, &csum_found);
 	if (csum_found > 0 && nodatasum) {
 		err |= ODD_CSUM_ITEM;
 		error("root %llu EXTENT_DATA[%llu %llu] nodatasum shouldn't have datasum",