1. First, dump the repository to some file
svnadmin dump /path/to/repo > dumpfile.txt2. Move your repository folder to somewhere else in order to backup, just in case
mv /path/to/repo /path/to/repo_backup3. Now, manually change the "Node-path:" and "Copy-to-path:" headers to insert "trunk/" into them
sed -e 's/^\(Node-path: \)\(.*\)/\1trunk\/\2/;s/^\(Copy-from-path:\)\(.*\)/\1trunk\/\2/' dumpfile > dumpfile.newIf you find above command too hard, just open the dumpfile in any text editor and do find and replace. :-) You should be replacing "Node-path:" with "Node-path:trunk/" and "Copy-to-path:" with "Copy-to-path:trunk/". Simple huh! 4. Create new repository
svnadmin create /path/to/repo5. Load modified dump file into newly created repository
svnadmin load newdumpfile.txt path/to/repo6. Finally, import 'tags' and 'branches' folder in the repository. Now, you will see your repository with proper structure in which you can make branches and tags of your project.