"short read" from filesystem, when can it happen?

Question

It is obvious that in general the read(2) system call can return less bytes than what was asked to be read. However, quite a few programs assume that when working with a local files, read(2) never returns less than what was asked (unless the file is shorter, of course).

So, my question is: on Linux, in which cases can read(2) return less than what was requested if reading from an open file and EOF is not encountered and the amount being read is a few kilobytes at maximum?

Some guesses:

• Can received signals interrupt a read like that, but not make it fail?
• Can different filesystems affect this behavior? Is there anything special about jffs2?