Re: [PATCH 10/11] xfs: enable bigtime for quota timers

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

On Sat, Aug 22, 2020 at 08:36:00AM +0100, Christoph Hellwig wrote:
> On Thu, Aug 20, 2020 at 07:12:34PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Enable the bigtime feature for quota timers.  We decrease the accuracy
> > of the timers to ~4s in exchange for being able to set timers up to the
> > bigtime maximum.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> > ---
> >  fs/xfs/libxfs/xfs_dquot_buf.c  |   32 ++++++++++++++++++++++++++++++--
> >  fs/xfs/libxfs/xfs_format.h     |   27 ++++++++++++++++++++++++++-
> >  fs/xfs/libxfs/xfs_quota_defs.h |    3 ++-
> >  fs/xfs/xfs_dquot.c             |   25 +++++++++++++++++++++----
> >  fs/xfs/xfs_dquot.h             |    3 ++-
> >  fs/xfs/xfs_ondisk.h            |    7 +++++++
> >  fs/xfs/xfs_qm.c                |    2 ++
> >  fs/xfs/xfs_qm_syscalls.c       |    9 +++++----
> >  fs/xfs/xfs_trans_dquot.c       |    6 ++++++
> >  9 files changed, 101 insertions(+), 13 deletions(-)
> > 
> > 
> > diff --git a/fs/xfs/libxfs/xfs_dquot_buf.c b/fs/xfs/libxfs/xfs_dquot_buf.c
> > index 7f5291022b11..f5997fbdd308 100644
> > --- a/fs/xfs/libxfs/xfs_dquot_buf.c
> > +++ b/fs/xfs/libxfs/xfs_dquot_buf.c
> > @@ -69,6 +69,13 @@ xfs_dquot_verify(
> >  	    ddq_type != XFS_DQTYPE_GROUP)
> >  		return __this_address;
> >  
> > +	if ((ddq->d_type & XFS_DQTYPE_BIGTIME) &&
> > +	    !xfs_sb_version_hasbigtime(&mp->m_sb))
> > +		return __this_address;
> > +
> > +	if ((ddq->d_type & XFS_DQTYPE_BIGTIME) && !ddq->d_id)
> > +		return __this_address;
> > +
> >  	if (id != -1 && id != be32_to_cpu(ddq->d_id))
> >  		return __this_address;
> >  
> > @@ -296,7 +303,15 @@ xfs_dquot_from_disk_timestamp(
> >  	time64_t		*timer,
> >  	__be32			dtimer)
> >  {
> > -	*timer = be32_to_cpu(dtimer);
> > +	uint64_t		t;
> > +
> > +	if (!timer || !(ddq->d_type & XFS_DQTYPE_BIGTIME)) {
> > +		*timer = be32_to_cpu(dtimer);
> 
> I don't think setting *time makes any sense if time is NULL..

Oops, yeah, I introduced that bug when reworking this function. :(

> > +		return;
> > +	}
> > +
> > +	t = be32_to_cpu(dtimer);
> > +	*timer = t << XFS_DQ_BIGTIME_SHIFT;
> 
> Why not:
> 
> 	*timer = (time64_t)be32_to_cpu(dtimer) << XFS_DQ_BIGTIME_SHIFT;
> 
> or (with my previous suggestion):
> 
> 	return (time64_t)be32_to_cpu(dtimer) << XFS_DQ_BIGTIME_SHIFT;

<nod>  Looks good to me.

--D

> 
> ?
> 
> > @@ -1227,13 +1227,15 @@ static inline void xfs_dinode_put_rdev(struct xfs_dinode *dip, xfs_dev_t rdev)
> >  #define XFS_DQTYPE_USER		0x01		/* user dquot record */
> >  #define XFS_DQTYPE_PROJ		0x02		/* project dquot record */
> >  #define XFS_DQTYPE_GROUP	0x04		/* group dquot record */
> > +#define XFS_DQTYPE_BIGTIME	0x08		/* large expiry timestamps */
> >  
> >  /* bitmask to determine if this is a user/group/project dquot */
> >  #define XFS_DQTYPE_REC_MASK	(XFS_DQTYPE_USER | \
> >  				 XFS_DQTYPE_PROJ | \
> >  				 XFS_DQTYPE_GROUP)
> >  
> > -#define XFS_DQTYPE_ANY		(XFS_DQTYPE_REC_MASK)
> > +#define XFS_DQTYPE_ANY		(XFS_DQTYPE_REC_MASK | \
> > +				 XFS_DQTYPE_BIGTIME)
> >  
> >  /*
> >   * XFS Quota Timers
> > @@ -1270,6 +1272,29 @@ static inline void xfs_dinode_put_rdev(struct xfs_dinode *dip, xfs_dev_t rdev)
> >  #define XFS_DQ_GRACE_MIN	((int64_t)0)
> >  #define XFS_DQ_GRACE_MAX	((int64_t)U32_MAX)
> >  
> > +/*
> > + * When bigtime is enabled, we trade a few bits of precision to expand the
> > + * expiration timeout range to match that of big inode timestamps.  The grace
> > + * periods stored in dquot 0 are not shifted, since they record an interval,
> > + * not a timestamp.
> > + */
> > +#define XFS_DQ_BIGTIME_SHIFT	(2)
> > +#define XFS_DQ_BIGTIME_SLACK	((int64_t)(1ULL << XFS_DQ_BIGTIME_SHIFT) - 1)
> > +
> > +/*
> > + * Smallest possible quota expiration with big timestamps, which is
> > + * Jan  1 00:00:01 UTC 1970.
> > + */
> > +#define XFS_DQ_BIGTIMEOUT_MIN		(XFS_DQ_TIMEOUT_MIN)
> > +
> > +/*
> > + * Largest supported quota expiration with traditional timestamps, which is
> > + * the largest bigtime inode timestamp, or Jul  2 20:20:25 UTC 2486.  The field
> 
> This adds and > 80 char line.