fuse: no abort on interrupt

Don't set 'aborted' flag on a request if it's interrupted.  We have to wait
for the answer anyway, and this would only a very little time while copying
the reply.

This means, that write() on the fuse device will not return -ENOENT during
normal operation, only if the filesystem is aborted by a forced umount or
through the fusectl interface.

This could simplify userspace code somewhat when backward compatibility with
earlier kernel versions is not required.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/fuse/dev.c

@@ -273,28 +273,41 @@ static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
 			queue_interrupt(fc, req);
 	}
 
-	if (req->force) {
-		spin_unlock(&fc->lock);
-		wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
-		spin_lock(&fc->lock);
-	} else {
+	if (!req->force) {
 		sigset_t oldset;
 
 		/* Only fatal signals may interrupt this */
 		block_sigs(&oldset);
 		wait_answer_interruptible(fc, req);
 		restore_sigs(&oldset);
-	}
 
 		if (req->aborted)
 			goto aborted;
 		if (req->state == FUSE_REQ_FINISHED)
 			return;
 
+		/* Request is not yet in userspace, bail out */
+		if (req->state == FUSE_REQ_PENDING) {
+			list_del(&req->list);
+			__fuse_put_request(req);
 			req->out.h.error = -EINTR;
-	req->aborted = 1;
+			return;
+		}
+	}
+
+	/*
+	 * Either request is already in userspace, or it was forced.
+	 * Wait it out.
+	 */
+	spin_unlock(&fc->lock);
+	wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
+	spin_lock(&fc->lock);
+
+	if (!req->aborted)
+		return;
 
  aborted:
+	BUG_ON(req->state != FUSE_REQ_FINISHED);
 	if (req->locked) {
 		/* This is uninterruptible sleep, because data is
 		   being copied to/from the buffers of req.  During
@@ -305,14 +318,6 @@ static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
 		wait_event(req->waitq, !req->locked);
 		spin_lock(&fc->lock);
 	}
-	if (req->state == FUSE_REQ_PENDING) {
-		list_del(&req->list);
-		__fuse_put_request(req);
-	} else if (req->state == FUSE_REQ_SENT) {
-		spin_unlock(&fc->lock);
-		wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
-		spin_lock(&fc->lock);
-	}
 }
 
 static unsigned len_args(unsigned numargs, struct fuse_arg *args)