Re: [PATCH] add check do_direct_IO() return val

Joe Jin
2007-07-27T07:16:00Z

> I think we still want to run dio_cleanup() if do_direct_IO() failed?
> Otherwise we can leak pages.
>
> And there's nothing special about EFAULT or ENOMEM here: if do_direct_IO()
> returns any error then that's it: we bale out, yes?
>

Yes, I think we'll out from here if get EFAULT/ENOMEM error, also maybe -EIO
return, return diretly should ok.

> In fact I'm suspecting that this is what the code in there used to do.
> Something like:
>
> for (...) {
> ...
> ret = do_direct_IO(...);
> ...
> if (ret) {
> dio_dleanup(dio);
> break
> }
> }
> return ret;
>

Yes, we need call dio_cleanup() to release page cache, I lost it.

However, we need do more while return -ENOTBLK, right?
so I think the patch maybe like following:

--- linux-2.6.22/fs/direct-io.c.orig 2007-07-27 14:39:15.000000000 +0800
+++ linux-2.6.22/fs/direct-io.c 2007-07-27 15:08:58.000000000 +0800
@@ -1032,18 +1032,19 @@ direct_io_worker(int rw, struct kiocb *i
blkbits);

if (ret) {
+ if (ret == -ENOTBLK && (rw & WRITE)) {
+ /*
+ * The remaining part of the request will be
+ * be handled by buffered I/O when we return
+ */
+ ret = 0;
+ break;
+ }
dio_cleanup(dio);
- break;
+ goto out;
}
} /* end iovec loop */

- if (ret == -ENOTBLK && (rw & WRITE)) {
- /*
- * The remaining part of the request will be
- * be handled by buffered I/O when we return
- */
- ret = 0;
- }
/*
* There may be some unwritten disk at the end of a part-written
* fs-block-sized block. Go zero that now.

> _
>
> However I'd like to ask you guys to carefully review and test that please.
>
Gurudas, would you please give more test of this patch?

Thanks,
Joe