diff --git a/cmds-check.c b/cmds-check.c
index 1dba298..567ca80 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -371,6 +371,17 @@ struct root_item_info {
 };
 
 /*
+ * Use inode_item_fix_info as function check_inode_item's arg.
+ */
+struct inode_item_fix_info {
+	u64 ino;
+	u64 isize;
+	u64 nbytes;
+
+	int err;
+};
+
+/*
  * Error bit for low memory mode check.
  *
  * Currently no caller cares about it yet.  Just internal use for error
@@ -1866,13 +1877,16 @@ struct node_refs {
 static int update_nodes_refs(struct btrfs_root *root, u64 bytenr,
 			     struct node_refs *nrefs, u64 level);
 static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path,
-			    unsigned int ext_ref);
-
+			    unsigned int ext_ref,
+			    struct inode_item_fix_info *info);
+static int repair_inode_item(struct btrfs_root *root,
+			     struct inode_item_fix_info *info);
 static int process_one_leaf_v2(struct btrfs_root *root, struct btrfs_path *path,
 			       struct node_refs *nrefs, int *level, int ext_ref)
 {
 	struct extent_buffer *cur = path->nodes[0];
 	struct btrfs_key key;
+	struct inode_item_fix_info info;
 	u64 cur_bytenr;
 	u32 nritems;
 	u64 first_ino = 0;
@@ -1881,6 +1895,7 @@ static int process_one_leaf_v2(struct btrfs_root *root, struct btrfs_path *path,
 	int ret = 0; /* Final return value */
 	int err = 0; /* Positive error bitmap */
 
+	memset(&info, 0, sizeof(info));
 	cur_bytenr = cur->start;
 
 	/* skip to first inode item or the first inode number change */
@@ -1900,8 +1915,26 @@ static int process_one_leaf_v2(struct btrfs_root *root, struct btrfs_path *path,
 	path->slots[0] = i;
 
 again:
-	err |= check_inode_item(root, path, ext_ref);
+	err |= check_inode_item(root, path, ext_ref, &info);
+
+	if (repair && (err & ~LAST_ITEM)) {
+		ret = repair_inode_item(root, &info);
 
+		if (ret < 0)
+			goto out;
+		/*
+		 * if some errors was repaired, path shall be searched
+		 * again since path has been changed
+		 */
+		if (ret == 0) {
+			btrfs_item_key_to_cpu(path->nodes[0], &key,
+					      path->slots[0]);
+			btrfs_release_path(path);
+			btrfs_search_slot(NULL, root, &key, path, 0, 0);
+
+			cur = path->nodes[0];
+		}
+	}
 	if (err & LAST_ITEM)
 		goto out;
 
@@ -2211,7 +2244,8 @@ out:
 }
 
 static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path,
-			    unsigned int ext_ref);
+			    unsigned int ext_ref,
+			    struct inode_item_fix_info *info);
 
 static int walk_down_tree_v2(struct btrfs_root *root, struct btrfs_path *path,
 			     int *level, struct node_refs *nrefs, int ext_ref)
@@ -2293,7 +2327,7 @@ static int walk_down_tree_v2(struct btrfs_root *root, struct btrfs_path *path,
 		}
 
 		ret = check_child_node(root, cur, path->slots[*level], next);
-		if (ret < 0) 
+		if (ret < 0)
 			break;
 
 		if (btrfs_is_leaf(next))
@@ -2383,6 +2417,105 @@ out:
 	return ret;
 }
 
+/*
+ * Set inode's nbytes to correct value in @info
+ *
+ * Returns <0  means on error
+ * Returns  0  means successful repair
+ */
+static int repair_inode_nbytes_lowmem(struct btrfs_trans_handle *trans,
+				      struct btrfs_root *root,
+				      struct inode_item_fix_info *info)
+{
+	struct btrfs_inode_item *ei;
+	struct btrfs_key key;
+	struct btrfs_path path;
+	int ret;
+
+	ASSERT(info);
+	key.objectid = info->ino;
+	key.type = BTRFS_INODE_ITEM_KEY;
+	key.offset = 0;
+
+	ret = btrfs_search_slot(trans, root, &key, &path, 0, 1);
+	if (ret < 0)
+		goto out;
+	if (ret > 0) {
+		ret = -ENOENT;
+		goto out;
+	}
+
+	ei = btrfs_item_ptr(path.nodes[0], path.slots[0],
+			    struct btrfs_inode_item);
+	btrfs_set_inode_nbytes(path.nodes[0], ei, info->nbytes);
+	btrfs_mark_buffer_dirty(path.nodes[0]);
+	printf("reset nbytes for inode %llu root %llu\n", info->ino,
+	       root->root_key.objectid);
+out:
+	btrfs_release_path(&path);
+	return ret;
+}
+
+/*
+ * repair_inode_item - repair inode item errors
+ *
+ * Repair the inode item if error can be repaired. Any caller should compare
+ * @info->err with the before, if err diffs, some contexts should be notified.
+ *
+ * @root:     subvolume_root
+ * @info:     contains correct values and error
+ *            when it returns, @info stores the unrepairable errors
+ *
+ * Returns < 0 represents repair function error
+ * Returns 0   represents have fixed some errors or no error at all
+ * Returns > 0 represents it can't fix any error
+ */
+static int repair_inode_item(struct btrfs_root *root,
+			     struct inode_item_fix_info *info)
+{
+	struct btrfs_trans_handle *trans;
+	int ret = 0;
+	int err;
+
+	ASSERT(info);
+	err = info->err;
+	if (!err) {
+		/* nothing to repair */
+		ret = 0;
+		goto out;
+	}
+	if (!(err & NBYTES_ERROR)) {
+		warning("root %llu INODE[%llu] have error(s) can't repair, error : %d",
+			root->objectid,	info->ino, err);
+		/* can't fix any errors, ret should be positive */
+		ret = err;
+		goto out;
+	}
+
+	trans = btrfs_start_transaction(root, 1);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out;
+	}
+
+	if (err & NBYTES_ERROR) {
+		ret = repair_inode_nbytes_lowmem(trans, root, info);
+		if (ret == 0)
+			err &= ~NBYTES_ERROR;
+		else if (ret < 0)
+			goto out;
+	}
+
+	if (err != info->err) {
+		info->err = err;
+		ret = 0;
+	}
+
+	btrfs_commit_transaction(trans, root);
+out:
+	return ret;
+}
+
 static int repair_inode_isize(struct btrfs_trans_handle *trans,
 			      struct btrfs_root *root, struct btrfs_path *path,
 			      struct inode_record *rec)
@@ -4781,7 +4914,8 @@ static int check_file_extent(struct btrfs_root *root, struct btrfs_key *fkey,
  * Return >0 for error or hit the traversal is done(by error bitmap)
  */
 static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path,
-			    unsigned int ext_ref)
+			    unsigned int ext_ref,
+			    struct inode_item_fix_info *info)
 {
 	struct extent_buffer *node;
 	struct btrfs_inode_item *ii;
@@ -4821,6 +4955,7 @@ static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path,
 	dir = imode_to_type(mode) == BTRFS_FT_DIR;
 	nlink = btrfs_inode_nlink(node, ii);
 	nodatasum = btrfs_inode_flags(node, ii) & BTRFS_INODE_NODATASUM;
+	info->ino = inode_id;
 
 	while (1) {
 		ret = btrfs_next_item(root, path);
@@ -4924,11 +5059,13 @@ out:
 
 		if (nbytes != extent_size) {
 			err |= NBYTES_ERROR;
+			info->nbytes = extent_size;
 			error("root %llu INODE[%llu] nbytes(%llu) not equal to extent_size(%llu)",
 			      root->objectid, inode_id, nbytes, extent_size);
 		}
 	}
 
+	info->err = err & ~LAST_ITEM;
 	return err;
 }
 
@@ -4936,9 +5073,11 @@ static int check_fs_first_inode(struct btrfs_root *root, unsigned int ext_ref)
 {
 	struct btrfs_path path;
 	struct btrfs_key key;
+	struct inode_item_fix_info info;
 	int err = 0;
 	int ret;
 
+	memset(&info, 0, sizeof(info));
 	btrfs_init_path(&path);
 	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 	key.type = BTRFS_INODE_ITEM_KEY;
@@ -4952,12 +5091,17 @@ static int check_fs_first_inode(struct btrfs_root *root, unsigned int ext_ref)
 		err |= INODE_ITEM_MISSING;
 	}
 
-	err |= check_inode_item(root, &path, ext_ref);
+	err |= check_inode_item(root, &path, ext_ref, &info);
 	err &= ~LAST_ITEM;
 	if (err && !ret)
 		ret = -EIO;
 out:
 	btrfs_release_path(&path);
+	if (repair) {
+		ret = repair_inode_item(root, &info);
+		if (!info.err)
+			ret = 0;
+	}
 	return ret;
 }
 
@@ -12722,8 +12866,7 @@ int cmd_check(int argc, char **argv)
 	 * Not supported yet
 	 */
 	if (repair && check_mode == CHECK_MODE_LOWMEM) {
-		error("low memory mode doesn't support repair yet");
-		exit(1);
+		error("low memory mode supports repair partailly");
 	}
 
 	radix_tree_init();
