fuse: use exclusive lock when FUSE_I_CACHE_IO_MODE is set

This may be a typo. The comment has said shared locks are
not allowed when this bit is set. If using shared lock, the
wait in `fuse_file_cached_io_open` may be forever.

Fixes: 205c1d8 ("fuse: allow parallel dio writes with FUSE_DIRECT_IO_ALLOW_MMAP")
CC: stable@vger.kernel.org # v6.9
Signed-off-by: yangyun <yangyun50@huawei.com>
Reviewed-by: Bernd Schubert <bschubert@ddn.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Author: yangyun50

fs/fuse/file.c

@@ -1345,7 +1345,7 @@ static bool fuse_dio_wr_exclusive_lock(struct kiocb *iocb, struct iov_iter *from
 
 	/* shared locks are not allowed with parallel page cache IO */
 	if (test_bit(FUSE_I_CACHE_IO_MODE, &fi->state))
-		return false;
+		return true;
 
 	/* Parallel dio beyond EOF is not supported, at least for now. */
 	if (fuse_io_past_eof(iocb, from))