Bail out if glfs_creat failed

Otherwise we will get segfaults from gfapi when it tries to access the
invalid fd.

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/engines/glusterfs.c b/engines/glusterfs.c
index 94daab5..a64c687 100644
--- a/engines/glusterfs.c
+++ b/engines/glusterfs.c
@@ -160,8 +160,9 @@
 	       flags & O_RDONLY ? "ro" : "rw", td_read(td) ? "read" : "write");
 	g->fd = glfs_creat(g->fs, f->file_name, flags, 0644);
 	if (!g->fd) {
-		log_err("glfs_creat failed.\n");
 		ret = errno;
+		log_err("glfs_creat failed.\n");
+		return ret;
 	}
 	/* file for read doesn't exist or shorter than required, create/extend it */
 	if (td_read(td)) {