Re: [PATCH v2 4/7] xfs: add support for free space btree staging cursors

[Brian Foster <bfoster@redhat.com>]

On Mon, Mar 16, 2020 at 12:35:41PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Add support for btree staging cursors for the free space 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>
> ---
> v2: leave the LASTREC_UPDATE flag setting alone
> ---

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

>  fs/xfs/libxfs/xfs_alloc_btree.c |   93 ++++++++++++++++++++++++++++++++-------
>  fs/xfs/libxfs/xfs_alloc_btree.h |    7 +++
>  2 files changed, 84 insertions(+), 16 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_alloc_btree.c b/fs/xfs/libxfs/xfs_alloc_btree.c
> index a28041fdf4c0..60c453cb3ee3 100644
> --- a/fs/xfs/libxfs/xfs_alloc_btree.c
> +++ b/fs/xfs/libxfs/xfs_alloc_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_alloc_btree.h"
>  #include "xfs_alloc.h"
>  #include "xfs_extent_busy.h"
> @@ -471,18 +472,14 @@ static const struct xfs_btree_ops xfs_cntbt_ops = {
>  	.recs_inorder		= xfs_cntbt_recs_inorder,
>  };
>  
> -/*
> - * Allocate a new allocation btree cursor.
> - */
> -struct xfs_btree_cur *			/* new alloc btree cursor */
> -xfs_allocbt_init_cursor(
> -	struct xfs_mount	*mp,		/* file system mount point */
> -	struct xfs_trans	*tp,		/* transaction pointer */
> -	struct xfs_buf		*agbp,		/* buffer for agf structure */
> -	xfs_agnumber_t		agno,		/* allocation group number */
> -	xfs_btnum_t		btnum)		/* btree identifier */
> +/* Allocate most of a new allocation btree cursor. */
> +STATIC struct xfs_btree_cur *
> +xfs_allocbt_init_common(
> +	struct xfs_mount	*mp,
> +	struct xfs_trans	*tp,
> +	xfs_agnumber_t		agno,
> +	xfs_btnum_t		btnum)
>  {
> -	struct xfs_agf		*agf = agbp->b_addr;
>  	struct xfs_btree_cur	*cur;
>  
>  	ASSERT(btnum == XFS_BTNUM_BNO || btnum == XFS_BTNUM_CNT);
> @@ -495,17 +492,14 @@ xfs_allocbt_init_cursor(
>  	cur->bc_blocklog = mp->m_sb.sb_blocklog;
>  
>  	if (btnum == XFS_BTNUM_CNT) {
> -		cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_abtc_2);
>  		cur->bc_ops = &xfs_cntbt_ops;
> -		cur->bc_nlevels = be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNT]);
> +		cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_abtc_2);
>  		cur->bc_flags = XFS_BTREE_LASTREC_UPDATE;
>  	} else {
> -		cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_abtb_2);
>  		cur->bc_ops = &xfs_bnobt_ops;
> -		cur->bc_nlevels = be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNO]);
> +		cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_abtb_2);
>  	}
>  
> -	cur->bc_ag.agbp = agbp;
>  	cur->bc_ag.agno = agno;
>  	cur->bc_ag.abt.active = false;
>  
> @@ -515,6 +509,73 @@ xfs_allocbt_init_cursor(
>  	return cur;
>  }
>  
> +/*
> + * Allocate a new allocation btree cursor.
> + */
> +struct xfs_btree_cur *			/* new alloc btree cursor */
> +xfs_allocbt_init_cursor(
> +	struct xfs_mount	*mp,		/* file system mount point */
> +	struct xfs_trans	*tp,		/* transaction pointer */
> +	struct xfs_buf		*agbp,		/* buffer for agf structure */
> +	xfs_agnumber_t		agno,		/* allocation group number */
> +	xfs_btnum_t		btnum)		/* btree identifier */
> +{
> +	struct xfs_agf		*agf = agbp->b_addr;
> +	struct xfs_btree_cur	*cur;
> +
> +	cur = xfs_allocbt_init_common(mp, tp, agno, btnum);
> +	if (btnum == XFS_BTNUM_CNT)
> +		cur->bc_nlevels = be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNT]);
> +	else
> +		cur->bc_nlevels = be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNO]);
> +
> +	cur->bc_ag.agbp = agbp;
> +
> +	return cur;
> +}
> +
> +/* Create a free space btree cursor with a fake root for staging. */
> +struct xfs_btree_cur *
> +xfs_allocbt_stage_cursor(
> +	struct xfs_mount	*mp,
> +	struct xbtree_afakeroot	*afake,
> +	xfs_agnumber_t		agno,
> +	xfs_btnum_t		btnum)
> +{
> +	struct xfs_btree_cur	*cur;
> +
> +	cur = xfs_allocbt_init_common(mp, NULL, agno, btnum);
> +	xfs_btree_stage_afakeroot(cur, afake);
> +	return cur;
> +}
> +
> +/*
> + * Install a new free space btree root.  Caller is responsible for invalidating
> + * and freeing the old btree blocks.
> + */
> +void
> +xfs_allocbt_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_roots[cur->bc_btnum] = cpu_to_be32(afake->af_root);
> +	agf->agf_levels[cur->bc_btnum] = cpu_to_be32(afake->af_levels);
> +	xfs_alloc_log_agf(tp, agbp, XFS_AGF_ROOTS | XFS_AGF_LEVELS);
> +
> +	if (cur->bc_btnum == XFS_BTNUM_BNO) {
> +		xfs_btree_commit_afakeroot(cur, tp, agbp, &xfs_bnobt_ops);
> +	} else {
> +		cur->bc_flags |= XFS_BTREE_LASTREC_UPDATE;
> +		xfs_btree_commit_afakeroot(cur, tp, agbp, &xfs_cntbt_ops);
> +	}
> +}
> +
>  /*
>   * Calculate number of records in an alloc btree block.
>   */
> diff --git a/fs/xfs/libxfs/xfs_alloc_btree.h b/fs/xfs/libxfs/xfs_alloc_btree.h
> index c9305ebb69f6..047f09f0be3c 100644
> --- a/fs/xfs/libxfs/xfs_alloc_btree.h
> +++ b/fs/xfs/libxfs/xfs_alloc_btree.h
> @@ -13,6 +13,7 @@
>  struct xfs_buf;
>  struct xfs_btree_cur;
>  struct xfs_mount;
> +struct xbtree_afakeroot;
>  
>  /*
>   * Btree block header size depends on a superblock flag.
> @@ -48,8 +49,14 @@ struct xfs_mount;
>  extern struct xfs_btree_cur *xfs_allocbt_init_cursor(struct xfs_mount *,
>  		struct xfs_trans *, struct xfs_buf *,
>  		xfs_agnumber_t, xfs_btnum_t);
> +struct xfs_btree_cur *xfs_allocbt_stage_cursor(struct xfs_mount *mp,
> +		struct xbtree_afakeroot *afake, xfs_agnumber_t agno,
> +		xfs_btnum_t btnum);
>  extern int xfs_allocbt_maxrecs(struct xfs_mount *, int, int);
>  extern xfs_extlen_t xfs_allocbt_calc_size(struct xfs_mount *mp,
>  		unsigned long long len);
>  
> +void xfs_allocbt_commit_staged_btree(struct xfs_btree_cur *cur,
> +		struct xfs_trans *tp, struct xfs_buf *agbp);
> +
>  #endif	/* __XFS_ALLOC_BTREE_H__ */
>