linux-kernel - Re: [PATCH v2] loop: Add LOOP_SET_DIRECT

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Message-ID: <20190808235150.GA208797@google.com>
Date:   Thu, 8 Aug 2019 19:51:50 -0400
From:   Joel Fernandes <joel@...lfernandes.org>
To:     Alessio Balsini <balsini@...roid.com>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        axboe@...nel.dk, dvander@...il.com, elsk@...gle.com,
        gregkh@...uxfoundation.org, kernel-team@...roid.com
Subject: Re: [PATCH v2] loop: Add LOOP_SET_DIRECT_IO to compat ioctl

On Wed, Aug 07, 2019 at 01:48:28AM +0100, Alessio Balsini wrote:
> Enabling Direct I/O with loop devices helps reducing memory usage by
> avoiding double caching.  32 bit applications running on 64 bits systems
> are currently not able to request direct I/O because is missing from the
> lo_compat_ioctl.
> 
> This patch fixes the compatibility issue mentioned above by exporting
> LOOP_SET_DIRECT_IO as additional lo_compat_ioctl() entry.
> The input argument for this ioctl is a single long converted to a 1-bit
> boolean, so compatibility is preserved.

This commit message looks better now.

thanks,

 - Joel


> Cc: Jens Axboe <axboe@...nel.dk>
> Signed-off-by: Alessio Balsini <balsini@...roid.com>
> ---
>  drivers/block/loop.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 44c9985f352ab..2e2193f754ab0 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -1753,6 +1753,7 @@ static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
>  	case LOOP_SET_FD:
>  	case LOOP_CHANGE_FD:
>  	case LOOP_SET_BLOCK_SIZE:
> +	case LOOP_SET_DIRECT_IO:
>  		err = lo_ioctl(bdev, mode, cmd, arg);
>  		break;
>  	default:
> -- 
> 2.23.0.rc1.153.gdeed80330f-goog
>