merging individual files

Suppose that merging branch dev1 into master would result in three files, f1, f2, and f3 being changed, and that I only want to merge the changes for f1 and f2 and not the changes for f3 currently. Later on, I want to accept the f3 changes. Suppose further that the changes to f1, f2, and f3 occurred in a single commit to branch dev1.

What is the simplest way to use git to achieve that effect?

More generally, I need a way to accept the changes for one or two files while rejecting the changes for a potentially large number of files, then later on accepting the changes for the large number of files.

I work at a company where perforce is currently used for all development and am trying to work out the git equivalents to all of the perforce flows we use. This workflow is the only one that I am stumped on.

One solution that occurs to me is to create a temporary branch off of the (most recent) common ancestor of master and br1, let's say br2, checkout the files from br1 that I want to merge into master and commit those to br2, then merge br2 into master:

git checkout common_ancestor_commit git checkout -b br2 git checkout br1 f1 f2 git commit git checkout master git merge br2 git branch -d br2

This strikes me as not too bad of a procedure, as long as there is a graceful way of determining the most recent common ancestor of br1 and master. What's the simplest way of doing that?