Re: [PATCH 2/4] mtd: rfd_ftl: add discard support

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Sean,

Sean Young <sean@mess.org> wrote on Tue, 13 Jul 2021 10:44:01 +0100:

> I proposed this change 16 years ago before discard was a feature in
> the block layer: https://lwn.net/Articles/162776/
> 
> Now that the block layer has discard, we can finally merge this change.

Can you explain why this is needed here?

(also please add the maintainers in Cc: for the v2)

> Signed-off-by: Sean Young <sean@mess.org>
> ---
>  drivers/mtd/rfd_ftl.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/drivers/mtd/rfd_ftl.c b/drivers/mtd/rfd_ftl.c
> index 7b243f2b2fa3..7f5f6d247cae 100644
> --- a/drivers/mtd/rfd_ftl.c
> +++ b/drivers/mtd/rfd_ftl.c
> @@ -705,6 +705,34 @@ static int rfd_ftl_writesect(struct mtd_blktrans_dev *dev, u_long sector, char *
>  	return rc;
>  }
>  
> +static int rfd_ftl_discardsect(struct mtd_blktrans_dev *dev,
> +			       unsigned long sector, unsigned int nr_sects)
> +{
> +	struct partition *part = (struct partition *)dev;
> +	u_long addr;
> +	int rc;
> +
> +	while (nr_sects) {
> +		if (sector >= part->sector_count)
> +			return -EIO;
> +
> +		addr = part->sector_map[sector];
> +
> +		if (addr != -1) {
> +			rc = mark_sector_deleted(part, addr);
> +			if (rc)
> +				return rc;
> +
> +			part->sector_map[sector] = -1;
> +		}
> +
> +		sector++;
> +		nr_sects--;
> +	}
> +
> +	return 0;
> +}
> +
>  static int rfd_ftl_getgeo(struct mtd_blktrans_dev *dev, struct hd_geometry *geo)
>  {
>  	struct partition *part = (struct partition*)dev;
> @@ -786,6 +814,7 @@ static struct mtd_blktrans_ops rfd_ftl_tr = {
>  
>  	.readsect	= rfd_ftl_readsect,
>  	.writesect	= rfd_ftl_writesect,
> +	.discard	= rfd_ftl_discardsect,
>  	.getgeo		= rfd_ftl_getgeo,
>  	.add_mtd	= rfd_ftl_add_mtd,
>  	.remove_dev	= rfd_ftl_remove_dev,




Thanks,
Miquèl

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