Add warning about potentially missing O_DIRECT support or bad alignment
If the first O_DIRECT fails, then it's likely because:
1) The file system does not support O_DIRECT, or
2) The user set iomem_align to an unsupported value.
Let the user know, otherwise they only see EINVAL and may not realize
why things aren't working.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/ioengines.c b/ioengines.c
index 4c97d03..7f0a5c4 100644
--- a/ioengines.c
+++ b/ioengines.c
@@ -245,6 +245,18 @@
unlock_file(td, io_u->file);
+ /*
+ * Add warning for O_DIRECT so that users have an easier time
+ * spotting potentially bad alignment. If this triggers for the first
+ * IO, then it's likely an alignment problem or because the host fs
+ * does not support O_DIRECT
+ */
+ if (io_u->error == EINVAL && td->io_issues[io_u->ddir] == 1 &&
+ td->o.odirect) {
+ log_info("fio: first direct IO errored. File system may not "
+ "support direct IO, or iomem_align= is bad.\n");
+ }
+
if (!td->io_ops->commit) {
io_u_mark_submit(td, 1);
io_u_mark_complete(td, 1);