Re: [PATCH] xfs: check if device support discard in xfs_ioc_trim()

[Alex Elder <aelder@sgi.com>]

On Tue, 2011-02-15 at 18:07 +0100, Lukas Czerner wrote:
> Right now we, are relying on the fact that when we attempt to actually do
> the discard, blkdev_issue_discar() returns -EOPNOTSUPP and the user is
> informed that the device does not support discard.
> 
> However, in the case where the we do not hit any suitable free extent to
> trim in FITRIM code, it will finish without any error. This is very
> confusing, because it seems that FITRIM was successful even though the
> device does not actually supports discard.
> 
> Solution: Check for the discard support before attempt to search for
> free extents.
> 
> Signed-off-by: Lukas Czerner <lczerner@redhat.com>
> ---
>  fs/xfs/linux-2.6/xfs_discard.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/xfs/linux-2.6/xfs_discard.c b/fs/xfs/linux-2.6/xfs_discard.c
> index 05201ae..d61611c 100644
> --- a/fs/xfs/linux-2.6/xfs_discard.c
> +++ b/fs/xfs/linux-2.6/xfs_discard.c
> @@ -152,6 +152,8 @@ xfs_ioc_trim(
>  
>  	if (!capable(CAP_SYS_ADMIN))
>  		return -XFS_ERROR(EPERM);
> +	if (!blk_queue_discard(q))
> +		return -XFS_ERROR(EOPNOTSUPP);
>  	if (copy_from_user(&range, urange, sizeof(range)))
>  		return -XFS_ERROR(EFAULT);
>  

Looks good.

Reviewed-by: Alex Elder <aelder@sgi.com>


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