Re: [PATCH 6/6] xfs: allow individual quota grace period extension

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Mon, May 18, 2020 at 01:52:16PM -0500, Eric Sandeen wrote:
> The only grace period which can be set in the kernel today is for id 0,
> i.e. the default grace period for all users.  However, setting an
> individual grace period is useful; for example:
> 
>  Alice has a soft quota of 100 inodes, and a hard quota of 200 inodes
>  Alice uses 150 inodes, and enters a short grace period
>  Alice really needs to use those 150 inodes past the grace period
>  The administrator extends Alice's grace period until next Monday
> 
> vfs quota users such as ext4 can do this today, with setquota -T

Does setquota -T work on an XFS filesystem?  If so, does that mean that
xfs had a functionality gap where the admin could extend someone's grace
period on ext4 but trying the exact same command on xfs would do
nothing?  Or would it at least error out?

> To enable this for XFS, we simply move the timelimit assignment out
> from under the (id == 0) test.  Default setting remains under (id == 0).
> Note that this now is consistent with how we set warnings.
> 
> (Userspace requires updates to enable this as well; xfs_quota needs to
> parse new options, and setquota needs to set appropriate field flags.)

So ... xfs_quota simply never had the ability to do this, but what does
"setquota needs to set appropriate field flags" mean exactly?

--D

> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>  fs/xfs/xfs_qm_syscalls.c | 48 +++++++++++++++++++++++-----------------
>  1 file changed, 28 insertions(+), 20 deletions(-)
> 
> diff --git a/fs/xfs/xfs_qm_syscalls.c b/fs/xfs/xfs_qm_syscalls.c
> index 29c1d5d4104d..94d374820c7e 100644
> --- a/fs/xfs/xfs_qm_syscalls.c
> +++ b/fs/xfs/xfs_qm_syscalls.c
> @@ -555,32 +555,40 @@ xfs_qm_scall_setqlim(
>  		ddq->d_rtbwarns = cpu_to_be16(newlim->d_rt_spc_warns);
>  
>  	if (id == 0) {
> -		/*
> -		 * Timelimits for the super user set the relative time
> -		 * the other users can be over quota for this file system.
> -		 * If it is zero a default is used.  Ditto for the default
> -		 * soft and hard limit values (already done, above), and
> -		 * for warnings.
> -		 */
> -		if (newlim->d_fieldmask & QC_SPC_TIMER) {
> -			defq->btimelimit = newlim->d_spc_timer;
> -			ddq->d_btimer = cpu_to_be32(newlim->d_spc_timer);
> -		}
> -		if (newlim->d_fieldmask & QC_INO_TIMER) {
> -			defq->itimelimit = newlim->d_ino_timer;
> -			ddq->d_itimer = cpu_to_be32(newlim->d_ino_timer);
> -		}
> -		if (newlim->d_fieldmask & QC_RT_SPC_TIMER) {
> -			defq->rtbtimelimit = newlim->d_rt_spc_timer;
> -			ddq->d_rtbtimer = cpu_to_be32(newlim->d_rt_spc_timer);
> -		}
>  		if (newlim->d_fieldmask & QC_SPC_WARNS)
>  			defq->bwarnlimit = newlim->d_spc_warns;
>  		if (newlim->d_fieldmask & QC_INO_WARNS)
>  			defq->iwarnlimit = newlim->d_ino_warns;
>  		if (newlim->d_fieldmask & QC_RT_SPC_WARNS)
>  			defq->rtbwarnlimit = newlim->d_rt_spc_warns;
> -	} else {
> +	}
> +
> +	/*
> +	 * Timelimits for the super user set the relative time the other users
> +	 * can be over quota for this file system. If it is zero a default is
> +	 * used.  Ditto for the default soft and hard limit values (already
> +	 * done, above), and for warnings.
> +	 *
> +	 * For other IDs, userspace can bump out the grace period if over
> +	 * the soft limit.
> +	 */
> +	if (newlim->d_fieldmask & QC_SPC_TIMER)
> +		ddq->d_btimer = cpu_to_be32(newlim->d_spc_timer);
> +	if (newlim->d_fieldmask & QC_INO_TIMER)
> +		ddq->d_itimer = cpu_to_be32(newlim->d_ino_timer);
> +	if (newlim->d_fieldmask & QC_RT_SPC_TIMER)
> +		ddq->d_rtbtimer = cpu_to_be32(newlim->d_rt_spc_timer);
> +
> +	if (id == 0) {
> +		if (newlim->d_fieldmask & QC_SPC_TIMER)
> +			defq->btimelimit = newlim->d_spc_timer;
> +		if (newlim->d_fieldmask & QC_INO_TIMER)
> +			defq->itimelimit = newlim->d_ino_timer;
> +		if (newlim->d_fieldmask & QC_RT_SPC_TIMER)
> +			defq->rtbtimelimit = newlim->d_rt_spc_timer;
> +	}
> +
> +	if (id != 0) {
>  		/*
>  		 * If the user is now over quota, start the timelimit.
>  		 * The user will not be 'warned'.
> -- 
> 2.17.0
> 
>