POSTing file information via ajax after upload using PlUpload - asp.net-mvc-3

Question

I'm using a customized example of plupload, where
one or more files are first uploaded to an Amazon S3 bucket, and
then file info + user-entered data (e.g. description) is POSTed
via ajax to my controller action in a loop.
This controller action then verifies that the file was upload to the S3 bucket and then saves the info into the database, returning a success or failure to the ajax call.
I use the 'UploadComplete' event to check for any upload errors, and if there are none, perform the actual POSTs in a loop.
What I'd like to do is wait until the entire loop has finished processing and then display the confirmation message (all success, all failed, mix of both) accordingly.
Current code:
uploader.bind('UploadComplete', function (up, files) {
var errorsPresent = false;
var errors = '';
// re-enable buttons
$('div.plupload_buttons a').removeClass('disabled');
$.each(uploader.files, function (i, file) {
if (errorDescArray.hasOwnProperty(file.id)) {
errorsPresent = true;
errors += errorDescArray[file.id] + '<br />';
}
else if (file.status = plupload.DONE) {
var jqXhr = $.post('/documents/add', {
'__RequestVerificationToken': $('#__AjaxAntiForgeryForm input[name=__RequestVerificationToken]').val(),
'filename': file.name,
'size': file.size,
'location': $('#' + file.id + '_location').val(),
'description': $('#filedesc_text_' + file.id).text()
}).error(function (response) {
errorsPresent = true;
errors += response.responseText + '<br />';
});
}
});
//
if (errorsPresent) {
$('#uploadErrors').html('<div data-alert="alert" class="alert-message block-message fade in error">×<p>' + errors + '</p></div>');
}
else {
// set confirmation message
var message = files.length + ' file(s) were successfully uploaded.';
// clear file list
$('ul.plupload_filelist').html('');
// remove files from list
uploader.splice();
// hide modal
$('#upload-modal').modal('hide');
// show confirmation
$('#flashMessage').html('<div data-alert="alert" class="alert-message block-message fade in success">×<p>' + message + '</p></div>');
}
});
The above is obviously flawed in that the second half of the snippet doesn't really wait for the POSTs to complete, with the result that the success confirmation is displayed even if POST has an error response.
So my question is this: How do I perform an ajax post in a loop (unless there's a better way) and process the confirmation message after the loop has finished processing?