Re: [PATCH 3/4] xfs: create convenience wrappers for incore quota block reservations

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Jan 25, 2021 at 10:15:19AM -0500, Brian Foster wrote:
> On Sat, Jan 23, 2021 at 10:51:51AM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > Create a couple of convenience wrappers for creating and deleting quota
> > block reservations against future changes.
> > 
> > Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> > ---
> >  fs/xfs/libxfs/xfs_bmap.c |   12 ++++++------
> >  fs/xfs/xfs_quota.h       |   19 +++++++++++++++++++
> >  fs/xfs/xfs_reflink.c     |    6 +++---
> >  3 files changed, 28 insertions(+), 9 deletions(-)
> > 
> > 
> > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> > index aea179212946..908b7d49da60 100644
> > --- a/fs/xfs/libxfs/xfs_bmap.c
> > +++ b/fs/xfs/libxfs/xfs_bmap.c
> > @@ -4067,9 +4067,12 @@ xfs_bmapi_reserve_delalloc(
> >  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
> >  	xfs_extlen_t		alen;
> >  	xfs_extlen_t		indlen;
> > +	bool			isrt;
> >  	int			error;
> >  	xfs_fileoff_t		aoff = off;
> >  
> > +	isrt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(ip);
> > + 
> What's the reason for checking isrt where we didn't before? Is that what
> the commit log means by "... against future changes?" (If so, a sentence
> or two more of "why" context in the commit log please..? :)

Well right now this function makes a delalloc reservation .... oh , the
rest of the function is totally broken wrt realtime anyway, so maybe I
should just ditch that isrt parameter completely.

--D

> Brian
> 
> >  	/*
> >  	 * Cap the alloc length. Keep track of prealloc so we know whether to
> >  	 * tag the inode before we return.
> > @@ -4098,8 +4101,7 @@ xfs_bmapi_reserve_delalloc(
> >  	 * blocks.  This number gets adjusted later.  We return if we haven't
> >  	 * allocated blocks already inside this loop.
> >  	 */
> > -	error = xfs_trans_reserve_quota_nblks(NULL, ip, (long)alen, 0,
> > -						XFS_QMOPT_RES_REGBLKS);
> > +	error = xfs_quota_reserve_blkres(ip, alen, isrt);
> >  	if (error)
> >  		return error;
> >  
> > @@ -4145,8 +4147,7 @@ xfs_bmapi_reserve_delalloc(
> >  	xfs_mod_fdblocks(mp, alen, false);
> >  out_unreserve_quota:
> >  	if (XFS_IS_QUOTA_ON(mp))
> > -		xfs_trans_unreserve_quota_nblks(NULL, ip, (long)alen, 0,
> > -						XFS_QMOPT_RES_REGBLKS);
> > +		xfs_quota_unreserve_blkres(ip, alen, isrt);
> >  	return error;
> >  }
> >  
> > @@ -4938,8 +4939,7 @@ xfs_bmap_del_extent_delay(
> >  	 * sb counters as we might have to borrow some blocks for the
> >  	 * indirect block accounting.
> >  	 */
> > -	error = xfs_trans_unreserve_quota_nblks(NULL, ip, del->br_blockcount, 0,
> > -			isrt ? XFS_QMOPT_RES_RTBLKS : XFS_QMOPT_RES_REGBLKS);
> > +	error = xfs_quota_unreserve_blkres(ip, del->br_blockcount, isrt);
> >  	if (error)
> >  		return error;
> >  	ip->i_delayed_blks -= del->br_blockcount;
> > diff --git a/fs/xfs/xfs_quota.h b/fs/xfs/xfs_quota.h
> > index bd28d17941e7..a25e3ce04c60 100644
> > --- a/fs/xfs/xfs_quota.h
> > +++ b/fs/xfs/xfs_quota.h
> > @@ -108,6 +108,12 @@ extern void xfs_qm_mount_quotas(struct xfs_mount *);
> >  extern void xfs_qm_unmount(struct xfs_mount *);
> >  extern void xfs_qm_unmount_quotas(struct xfs_mount *);
> >  
> > +static inline int
> > +xfs_quota_reserve_blkres(struct xfs_inode *ip, int64_t nblks, bool isrt)
> > +{
> > +	return xfs_trans_reserve_quota_nblks(NULL, ip, nblks, 0,
> > +			isrt ? XFS_QMOPT_RES_RTBLKS : XFS_QMOPT_RES_REGBLKS);
> > +}
> >  #else
> >  static inline int
> >  xfs_qm_vop_dqalloc(struct xfs_inode *ip, kuid_t kuid, kgid_t kgid,
> > @@ -136,6 +142,13 @@ static inline int xfs_trans_reserve_quota_bydquots(struct xfs_trans *tp,
> >  {
> >  	return 0;
> >  }
> > +
> > +static inline int
> > +xfs_quota_reserve_blkres(struct xfs_inode *ip, int64_t nblks, bool isrt)
> > +{
> > +	return 0;
> > +}
> > +
> >  #define xfs_qm_vop_create_dqattach(tp, ip, u, g, p)
> >  #define xfs_qm_vop_rename_dqattach(it)					(0)
> >  #define xfs_qm_vop_chown(tp, ip, old, new)				(NULL)
> > @@ -162,6 +175,12 @@ xfs_trans_unreserve_quota_nblks(struct xfs_trans *tp, struct xfs_inode *ip,
> >  	xfs_trans_reserve_quota_bydquots(tp, mp, ud, gd, pd, nb, ni, \
> >  				f | XFS_QMOPT_RES_REGBLKS)
> >  
> > +static inline int
> > +xfs_quota_unreserve_blkres(struct xfs_inode *ip, int64_t nblks, bool isrt)
> > +{
> > +	return xfs_quota_reserve_blkres(ip, -nblks, isrt);
> > +}
> > +
> >  extern int xfs_mount_reset_sbqflags(struct xfs_mount *);
> >  
> >  #endif	/* __XFS_QUOTA_H__ */
> > diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> > index 183142fd0961..0da1a603b7d8 100644
> > --- a/fs/xfs/xfs_reflink.c
> > +++ b/fs/xfs/xfs_reflink.c
> > @@ -508,9 +508,9 @@ xfs_reflink_cancel_cow_blocks(
> >  			xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
> >  
> >  			/* Remove the quota reservation */
> > -			error = xfs_trans_unreserve_quota_nblks(NULL, ip,
> > -					del.br_blockcount, 0,
> > -					XFS_QMOPT_RES_REGBLKS);
> > +			error = xfs_quota_unreserve_blkres(ip,
> > +					del.br_blockcount,
> > +					XFS_IS_REALTIME_INODE(ip));
> >  			if (error)
> >  				break;
> >  		} else {
> > 
>