[PATCH] fuse: add O_NONBLOCK support to FUSE device

I don't like duplicating the connected and list_empty tests in fuse_dev_readv,
but this seemed cleaner than adding the f_flags test to request_wait.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/fuse/dev.c

@@ -619,6 +619,12 @@ static ssize_t fuse_dev_readv(struct file *file, const struct iovec *iov,
 	err = -EPERM;
 	if (!fc)
 		goto err_unlock;
+
+	err = -EAGAIN;
+	if ((file->f_flags & O_NONBLOCK) && fc->connected &&
+	    list_empty(&fc->pending))
+		goto err_unlock;
+
 	request_wait(fc);
 	err = -ENODEV;
 	if (!fc->connected)