Re: [PATCH 6/7] xfs: add support for refcount btree staging cursors

[Brian Foster <bfoster@redhat.com>]

On Sun, Mar 15, 2020 at 04:51:19PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Add support for btree staging cursors for the refcount btrees.  This
> is needed both for online repair and also to convert xfs_repair to use
> btree bulk loading.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/libxfs/xfs_refcount_btree.c |   70 +++++++++++++++++++++++++++++++-----
>  fs/xfs/libxfs/xfs_refcount_btree.h |    6 +++
>  2 files changed, 66 insertions(+), 10 deletions(-)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_refcount_btree.c b/fs/xfs/libxfs/xfs_refcount_btree.c
> index e07a2c45f8ec..7fd6044a4f78 100644
> --- a/fs/xfs/libxfs/xfs_refcount_btree.c
> +++ b/fs/xfs/libxfs/xfs_refcount_btree.c
> @@ -12,6 +12,7 @@
>  #include "xfs_sb.h"
>  #include "xfs_mount.h"
>  #include "xfs_btree.h"
> +#include "xfs_btree_staging.h"
>  #include "xfs_refcount_btree.h"
>  #include "xfs_alloc.h"
>  #include "xfs_error.h"
> @@ -311,41 +312,90 @@ static const struct xfs_btree_ops xfs_refcountbt_ops = {
>  };
>  
>  /*
> - * Allocate a new refcount btree cursor.
> + * Initialize a new refcount btree cursor.
>   */
> -struct xfs_btree_cur *
> -xfs_refcountbt_init_cursor(
> +static struct xfs_btree_cur *
> +xfs_refcountbt_init_common(
>  	struct xfs_mount	*mp,
>  	struct xfs_trans	*tp,
> -	struct xfs_buf		*agbp,
>  	xfs_agnumber_t		agno)
>  {
> -	struct xfs_agf		*agf = agbp->b_addr;
>  	struct xfs_btree_cur	*cur;
>  
>  	ASSERT(agno != NULLAGNUMBER);
>  	ASSERT(agno < mp->m_sb.sb_agcount);
> -	cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_NOFS);
>  
> +	cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_NOFS);
>  	cur->bc_tp = tp;
>  	cur->bc_mp = mp;
>  	cur->bc_btnum = XFS_BTNUM_REFC;
>  	cur->bc_blocklog = mp->m_sb.sb_blocklog;
> -	cur->bc_ops = &xfs_refcountbt_ops;
>  	cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_refcbt_2);
>  
> -	cur->bc_nlevels = be32_to_cpu(agf->agf_refcount_level);
> -
> -	cur->bc_ag.agbp = agbp;
>  	cur->bc_ag.agno = agno;
>  	cur->bc_flags |= XFS_BTREE_CRC_BLOCKS;
>  
>  	cur->bc_ag.refc.nr_ops = 0;
>  	cur->bc_ag.refc.shape_changes = 0;
> +	cur->bc_ops = &xfs_refcountbt_ops;
> +	return cur;
> +}
> +
> +/* Create a btree cursor. */
> +struct xfs_btree_cur *
> +xfs_refcountbt_init_cursor(
> +	struct xfs_mount	*mp,
> +	struct xfs_trans	*tp,
> +	struct xfs_buf		*agbp,
> +	xfs_agnumber_t		agno)
> +{
> +	struct xfs_agf		*agf = agbp->b_addr;
> +	struct xfs_btree_cur	*cur;
> +
> +	cur = xfs_refcountbt_init_common(mp, tp, agno);
> +	cur->bc_nlevels = be32_to_cpu(agf->agf_refcount_level);
> +	cur->bc_ag.agbp = agbp;
> +	return cur;
> +}
> +
> +/* Create a btree cursor with a fake root for staging. */
> +struct xfs_btree_cur *
> +xfs_refcountbt_stage_cursor(
> +	struct xfs_mount	*mp,
> +	struct xbtree_afakeroot	*afake,
> +	xfs_agnumber_t		agno)
> +{
> +	struct xfs_btree_cur	*cur;
>  
> +	cur = xfs_refcountbt_init_common(mp, NULL, agno);
> +	xfs_btree_stage_afakeroot(cur, afake);
>  	return cur;
>  }
>  
> +/*
> + * Swap in the new btree root.  Once we pass this point the newly rebuilt btree
> + * is in place and we have to kill off all the old btree blocks.
> + */
> +void
> +xfs_refcountbt_commit_staged_btree(
> +	struct xfs_btree_cur	*cur,
> +	struct xfs_trans	*tp,
> +	struct xfs_buf		*agbp)
> +{
> +	struct xfs_agf		*agf = agbp->b_addr;
> +	struct xbtree_afakeroot	*afake = cur->bc_ag.afake;
> +
> +	ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
> +
> +	agf->agf_refcount_root = cpu_to_be32(afake->af_root);
> +	agf->agf_refcount_level = cpu_to_be32(afake->af_levels);
> +	agf->agf_refcount_blocks = cpu_to_be32(afake->af_blocks);
> +	xfs_alloc_log_agf(tp, agbp, XFS_AGF_REFCOUNT_BLOCKS |
> +				    XFS_AGF_REFCOUNT_ROOT |
> +				    XFS_AGF_REFCOUNT_LEVEL);
> +	xfs_btree_commit_afakeroot(cur, tp, agbp, &xfs_refcountbt_ops);
> +}
> +
>  /*
>   * Calculate the number of records in a refcount btree block.
>   */
> diff --git a/fs/xfs/libxfs/xfs_refcount_btree.h b/fs/xfs/libxfs/xfs_refcount_btree.h
> index ba416f71c824..69dc515db671 100644
> --- a/fs/xfs/libxfs/xfs_refcount_btree.h
> +++ b/fs/xfs/libxfs/xfs_refcount_btree.h
> @@ -13,6 +13,7 @@
>  struct xfs_buf;
>  struct xfs_btree_cur;
>  struct xfs_mount;
> +struct xbtree_afakeroot;
>  
>  /*
>   * Btree block header size
> @@ -46,6 +47,8 @@ struct xfs_mount;
>  extern struct xfs_btree_cur *xfs_refcountbt_init_cursor(struct xfs_mount *mp,
>  		struct xfs_trans *tp, struct xfs_buf *agbp,
>  		xfs_agnumber_t agno);
> +struct xfs_btree_cur *xfs_refcountbt_stage_cursor(struct xfs_mount *mp,
> +		struct xbtree_afakeroot *afake, xfs_agnumber_t agno);
>  extern int xfs_refcountbt_maxrecs(int blocklen, bool leaf);
>  extern void xfs_refcountbt_compute_maxlevels(struct xfs_mount *mp);
>  
> @@ -58,4 +61,7 @@ extern int xfs_refcountbt_calc_reserves(struct xfs_mount *mp,
>  		struct xfs_trans *tp, xfs_agnumber_t agno, xfs_extlen_t *ask,
>  		xfs_extlen_t *used);
>  
> +void xfs_refcountbt_commit_staged_btree(struct xfs_btree_cur *cur,
> +		struct xfs_trans *tp, struct xfs_buf *agbp);
> +
>  #endif	/* __XFS_REFCOUNT_BTREE_H__ */
>