[dm-devel] [PATCH] block: add a bi_error field to struct bio
Hannes Reinecke
hare at suse.de
Tue Jul 21 08:19:08 UTC 2015
On 07/20/2015 03:29 PM, Christoph Hellwig wrote:
> Currently we have two different ways to signal an I/O error on a BIO:
>
> (1) by clearing the BIO_UPTODATE flag
> (2) by returning a Linux errno value to the bi_end_io callback
>
> The first one has the drawback of only communicating a single possible
> error (-EIO), and the second one has the drawback of not beeing persistent
> when bios are queued up, and are not passed along from child to parent
> bio in the ever more popular chaining scenario. Having both mechanisms
> available has the additional drawback of utterly confusing driver authors
> and introducing bugs where various I/O submitters only deal with one of
> them, and the others have to add boilerplate code to deal with both kinds
> of error returns.
>
> So add a new bi_error field to store an errno value directly in struct
> bio and remove the existing mechanisms to clean all this up.
>
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
Very good improvement.
Reviewed-by: Hannes Reinecke <hare at suse.de>
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare at suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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