On Tue, 2017-04-18 at 08:52 -0700, Christoph Hellwig wrote:
> From: Christoph Hellwig <hch@xxxxxx>
>
> This is for the legacy floppy and ataflop drivers that currently abuse
> ->errors for this purpose. It's stashed away in a union to not grow
> the struct size, the other fields are either used by modern drivers
> for different purposes or the I/O scheduler before queing the I/O
> to drivers.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> include/linux/blkdev.h | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 5986e1250d7d..e618164462e8 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -175,6 +175,7 @@ struct request {
> struct rb_node rb_node; /* sort/lookup */
> struct bio_vec special_vec;
> void *completion_data;
> + int error_count; /* for legacy drivers, don't use */
> };
>
> /*
Hello Christoph,
Both blk-mq and the traditional block layer support a .cmd_size field to
make the block layer core allocate driver-specific data at the end of struct
request. Could that mechanism have been used for the error_count field?
Thanks,
Bart.
