How do I set permissions recursively on a dir (with ACL enabled)?

setfacl has a recursive option (-R) just like chmod:

  -R, --recursive
      Apply operations to all files and directories recursively. This
      option cannot be mixed with `--restore'.

it also allows for the use of the capital-x X permission, which means:

  execute only if the file is a directory or already has
  execute permission for some user (X)

so doing the following should work:

setfacl -R -m u:colleague:rwX .

(all quotes are from man setfacl for acl-2.2.52 as shipped with Debian)

As mentioned by umläute, the command setfacl -R with uppercase "X" is the way to go, like:

setfacl -R -m u:colleague:rwX .

However, for those who need to re-apply ACL recrusively (i.e like "re-apply permissions on sub-directories" à la Windows).

find . -mindepth 1 | xargs -n 50 setfacl -b --set-file=<(getfacl . | sed -e 's/x$/X/')

That command could be splited to avoid error like setfacl: foobar: Only directories can have default ACLs.

find . -mindepth 1 -type d| xargs -n 50 setfacl -b --set-file=<(getfacl . | sed -e 's/x$/X/')
find . -mindepth 1 -type f| xargs -n 50 setfacl -b --set-file=<(getfacl . | grep -v '^default:' | sed -e 's/x$/X/')

Note that the syntax <( something ) is Process Substitution, which is specific to bash. You may need to create a temporary file if you use another shell.