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

[Brian Foster <bfoster@redhat.com>]

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..? :)

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 {
>