I read this short story more than 30 years ago, in a collection of Fantasy and SF. It is not SF so it must be fantasy.
It is about a writer who used to be prolific but now has failed to give his editor what the latter is expecting. So, since it must be Fantasy, IIRC, the editor got help from some imp, or demon or whatever. Otherwise there would be no Fantasy aspect at all.
Anyway the writer is now locked in a room with ink constantly flowing into it. His only way to keep from drowning is to keep writing, very fast, in order to use more ink than what flows in. This is totally ridiculous since however fast his imagination allows him to write, doodling would be faster, to say nothing of dropping paper directly into the ink to absorb it.
But the way the author writes it is better than my synopsis, and it really gives an amusing story.