[PATCH] fuse: fix bug in aborted fuse_release_end()

There's a rather theoretical case of the BUG triggering in
fuse_reset_request():

  - iget() fails because of OOM after a successful CREATE_OPEN request
  - during IO on the resulting RELEASE request the connection is aborted

Fix and add warning to fuse_reset_request().
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

@@ -66,6 +66,12 @@ static void restore_sigs(sigset_t *oldset)
 	sigprocmask(SIG_SETMASK, oldset, NULL);
 }
 
+/*
+ * Reset request, so that it can be reused
+ *
+ * The caller must be _very_ careful to make sure, that it is holding
+ * the only reference to req
+ */
 void fuse_reset_request(struct fuse_req *req)
 {
 	int preallocated = req->preallocated;

fs/fuse/file.c

@@ -116,9 +116,14 @@ int fuse_open_common(struct inode *inode, struct file *file, int isdir)
 /* Special case for failed iget in CREATE */
 static void fuse_release_end(struct fuse_conn *fc, struct fuse_req *req)
 {
-	u64 nodeid = req->in.h.nodeid;
-	fuse_reset_request(req);
-	fuse_send_forget(fc, req, nodeid, 1);
+	/* If called from end_io_requests(), req has more than one
+	   reference and fuse_reset_request() cannot work */
+	if (fc->connected) {
+		u64 nodeid = req->in.h.nodeid;
+		fuse_reset_request(req);
+		fuse_send_forget(fc, req, nodeid, 1);
+	} else
+		fuse_put_request(fc, req);
 }
 
 void fuse_send_release(struct fuse_conn *fc, struct fuse_file *ff,