linux-kernel - Re: [PATCH 1/4] block: Allow drivers to implement BLKDISCARD and add BLKSECDISCARD

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Date:	Thu, 10 Jun 2010 09:58:54 +0300
From:	Adrian Hunter <adrian.hunter@...ia.com>
To:	Jens Axboe <axboe@...nel.dk>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH 1/4] block: Allow drivers to implement BLKDISCARD and
 add BLKSECDISCARD

Adrian Hunter wrote:
> From 328a858c01be1e0d08f4a4b1f43d9fd117a295e5 Mon Sep 17 00:00:00 2001
> From: Adrian Hunter <adrian.hunter@...ia.com>
> Date: Thu, 3 Jun 2010 10:46:04 +0300
> Subject: [PATCH 1/4] block: Allow drivers to implement BLKDISCARD and add BLKSECDISCARD
> 
> SD/MMC cards provide an erase operation that is too inefficient to
> allow file systems to use it, however it is still useful for
> userspace tools because it is still 10 - 100 times faster than
> writing zeroes.  Allow the MMC block driver to provide its own
> BLKDISCARD implementation for this purpose.
> 
> In addition, eMMC v4.4 cards can provide a secure erase operation
> which guarantees that all copies of the discarded sectors (for
> example created by garbage collection) will also be erased.  For
> this a new ioctl BLKSECDISCARD is added.

Ping?

> 
> Signed-off-by: Adrian Hunter <adrian.hunter@...ia.com>
> ---
>  block/compat_ioctl.c |    1 +
>  block/ioctl.c        |    9 +++++++++
>  include/linux/fs.h   |    1 +
>  3 files changed, 11 insertions(+), 0 deletions(-)
> 
> diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
> index f26051f..24a146d 100644
> --- a/block/compat_ioctl.c
> +++ b/block/compat_ioctl.c
> @@ -753,6 +753,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
>  	case BLKFLSBUF:
>  	case BLKROSET:
>  	case BLKDISCARD:
> +	case BLKSECDISCARD:
>  	/*
>  	 * the ones below are implemented in blkdev_locked_ioctl,
>  	 * but we call blkdev_ioctl, which gets the lock for us
> diff --git a/block/ioctl.c b/block/ioctl.c
> index e8eb679..985aa88 100644
> --- a/block/ioctl.c
> +++ b/block/ioctl.c
> @@ -232,12 +232,21 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
>  		if (!(mode & FMODE_WRITE))
>  			return -EBADF;
>  
> +		ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
> +		if (ret != -ENOTTY)
> +			return ret;
> +
>  		if (copy_from_user(range, (void __user *)arg, sizeof(range)))
>  			return -EFAULT;
>  
>  		return blk_ioctl_discard(bdev, range[0], range[1]);
>  	}
>  
> +	case BLKSECDISCARD:
> +		if (!(mode & FMODE_WRITE))
> +			return -EBADF;
> +		return __blkdev_driver_ioctl(bdev, mode, cmd, arg);
> +
>  	case HDIO_GETGEO: {
>  		struct hd_geometry geo;
>  
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 3428393..25a6058 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -309,6 +309,7 @@ struct inodes_stat_t {
>  #define BLKALIGNOFF _IO(0x12,122)
>  #define BLKPBSZGET _IO(0x12,123)
>  #define BLKDISCARDZEROES _IO(0x12,124)
> +#define BLKSECDISCARD _IO(0x12,125)
>  
>  #define BMAP_IOCTL 1		/* obsolete - kept for compatibility */
>  #define FIBMAP	   _IO(0x00,1)	/* bmap access */

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