Re: [patch] direct-io: propagate -ENOSPC errors

From: Carlos Maiolino
Date: Wed Mar 16 2016 - 09:25:29 EST


This looks good to me.

Reviewed-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>

On Mon, Mar 14, 2016 at 05:10:00PM -0400, Jeff Moyer wrote:
> dio_bio_complete turns all errors into -EIO. This is historical,
> since you used to only get 1 bit precision for errors (BIO_UPTODATE).
> Now that we get actual error codes, we can return the appropriate
> code to userspace. File systems seem to only propagate either EIO
> or ENOSPC, so I've followed suit in this patch.
>
> This fixes an issue where -ENOSPC was being turned into -EIO when
> testing dm-thin.
>
> Reported-by: Carlos Maiolino <cmaiolin@xxxxxxxxxx>
> Tested-by: Mike Snitzer <snitzer@xxxxxxxxxx>
> Signed-off-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
>
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index d6a9012..990e0aa 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -466,13 +466,15 @@ static int dio_bio_complete(struct dio *dio, struct bio *bio)
> {
> struct bio_vec *bvec;
> unsigned i;
> - int err;
>
> - if (bio->bi_error)
> + /* Only EIO and ENOSPC should be returned to userspace. */
> + if (bio->bi_error == 0 ||
> + bio->bi_error == -ENOSPC || bio->bi_error == -EIO)
> + dio->io_error = bio->bi_error;
> + else
> dio->io_error = -EIO;
>
> if (dio->is_async && dio->rw == READ && dio->should_dirty) {
> - err = bio->bi_error;
> bio_check_pages_dirty(bio); /* transfers ownership */
> } else {
> bio_for_each_segment_all(bvec, bio, i) {
> @@ -483,10 +485,9 @@ static int dio_bio_complete(struct dio *dio, struct bio *bio)
> set_page_dirty_lock(page);
> page_cache_release(page);
> }
> - err = bio->bi_error;
> bio_put(bio);
> }
> - return err;
> + return dio->io_error;
> }
>
> /*
> --
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--
Carlos