Re: [PATCH 7/9] xfs: have getfsmap fall back to the freesp btrees when rmap is not present

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

On Wed, Mar 01, 2017 at 12:59:20PM -0500, Brian Foster wrote:
> On Tue, Feb 28, 2017 at 10:46:35AM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > If the reverse-mapping btree isn't available, fall back to the
> > free space btrees to provide partial reverse mapping information.
> > The online scrub tool can make use of even partial information to
> > speed up the data block scan.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  fs/xfs/xfs_fsmap.c |   81 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> >  1 file changed, 78 insertions(+), 3 deletions(-)
> > 
> > 
> > diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c
> > index 2d0fa2a..56bbd24 100644
> > --- a/fs/xfs/xfs_fsmap.c
> > +++ b/fs/xfs/xfs_fsmap.c
> > @@ -40,6 +40,7 @@
> >  #include "xfs_fsmap.h"
> >  #include "xfs_refcount.h"
> >  #include "xfs_refcount_btree.h"
> > +#include "xfs_alloc_btree.h"
> >  
> >  /* Convert an xfs_fsmap to an fsmap. */
> >  void
> > @@ -158,6 +159,9 @@ xfs_fsmap_owner_from_rmap(
> >  	case XFS_RMAP_OWN_COW:
> >  		dest->fmr_owner = XFS_FMR_OWN_COW;
> >  		break;
> > +	case XFS_RMAP_OWN_NULL:	/* "free" */
> > +		dest->fmr_owner = XFS_FMR_OWN_FREE;
> > +		break;
> >  	default:
> >  		return -EFSCORRUPTED;
> >  	}
> > @@ -411,6 +415,31 @@ xfs_getfsmap_rtdev_helper(
> >  	return xfs_getfsmap_helper(cur->bc_tp, info, rec, rec_daddr);
> >  }
> >  
> > +/* Transform a bnobt irec into a fsmap */
> > +STATIC int
> > +xfs_getfsmap_datadev_bnobt_helper(
> > +	struct xfs_btree_cur		*cur,
> > +	struct xfs_alloc_rec_incore	*rec,
> > +	void				*priv)
> > +{
> > +	struct xfs_mount		*mp = cur->bc_mp;
> > +	struct xfs_getfsmap_info	*info = priv;
> > +	struct xfs_rmap_irec		irec;
> > +	xfs_fsblock_t			fsb;
> > +	xfs_daddr_t			rec_daddr;
> > +
> > +	fsb = XFS_AGB_TO_FSB(mp, cur->bc_private.a.agno, rec->ar_startblock);
> > +	rec_daddr = XFS_FSB_TO_DADDR(mp, fsb);
> > +
> 
> XFS_AGB_TO_DADDR()?

Fixed.

> > +	irec.rm_startblock = rec->ar_startblock;
> > +	irec.rm_blockcount = rec->ar_blockcount;
> > +	irec.rm_owner = XFS_RMAP_OWN_NULL;	/* "free" */
> > +	irec.rm_offset = 0;
> > +	irec.rm_flags = 0;
> > +
> > +	return xfs_getfsmap_helper(cur->bc_tp, info, &irec, rec_daddr);
> > +}
> > +
> >  /* Set rmap flags based on the getfsmap flags */
> >  static void
> >  xfs_getfsmap_set_irec_flags(
> > @@ -633,6 +662,51 @@ xfs_getfsmap_datadev_rmapbt(
> >  			xfs_getfsmap_datadev_rmapbt_end, NULL);
> >  }
> >  
> > +/* Report any gap at the end of bnobt records. */
> > +STATIC int
> > +xfs_getfsmap_datadev_bnobt_end(
> > +	struct xfs_btree_cur		*cur,
> > +	struct xfs_getfsmap_info	*info,
> > +	void				*priv)
> > +{
> > +	struct xfs_alloc_rec_incore	*key = priv;
> > +
> > +	return xfs_getfsmap_datadev_bnobt_helper(cur, key + 1, info);
> 
> Nit: please use key[1] (or maybe call it keys to be clear) here and
> below rather than pointer arithmetic.
> 
> Looks good aside from those couple nits and modulo the separate
> _query()/_end() callbacks thing.

Also fixed.

--D

> 
> Brian
> 
> > +}
> > +
> > +/* Actually query the bno btree. */
> > +STATIC int
> > +xfs_getfsmap_datadev_bnobt_query(
> > +	struct xfs_trans		*tp,
> > +	struct xfs_getfsmap_info	*info,
> > +	struct xfs_btree_cur		**curpp,
> > +	void				*priv)
> > +{
> > +	struct xfs_alloc_rec_incore	*key = priv;
> > +
> > +	*curpp = xfs_allocbt_init_cursor(tp->t_mountp, tp, info->agf_bp,
> > +			info->agno, XFS_BTNUM_BNO);
> > +	key->ar_startblock = info->low.rm_startblock;
> > +	(key + 1)->ar_startblock = info->high.rm_startblock;
> > +	return xfs_alloc_query_range(*curpp, key, key + 1,
> > +			xfs_getfsmap_datadev_bnobt_helper, info);
> > +}
> > +
> > +/* Execute a getfsmap query against the regular data device's bnobt. */
> > +STATIC int
> > +xfs_getfsmap_datadev_bnobt(
> > +	struct xfs_trans		*tp,
> > +	struct xfs_fsmap		*keys,
> > +	struct xfs_getfsmap_info	*info)
> > +{
> > +	struct xfs_alloc_rec_incore	akeys[2];
> > +
> > +	info->missing_owner = XFS_FMR_OWN_UNKNOWN;
> > +	return __xfs_getfsmap_datadev(tp, keys, info,
> > +			xfs_getfsmap_datadev_bnobt_query,
> > +			xfs_getfsmap_datadev_bnobt_end, &akeys[0]);
> > +}
> > +
> >  /* Do we recognize the device? */
> >  STATIC bool
> >  xfs_getfsmap_is_valid_device(
> > @@ -714,8 +788,6 @@ xfs_getfsmap(
> >  	int				i;
> >  	int				error = 0;
> >  
> > -	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
> > -		return -EOPNOTSUPP;
> >  	if (head->fmh_iflags & ~FMH_IF_VALID)
> >  		return -EINVAL;
> >  	if (!xfs_getfsmap_is_valid_device(mp, &head->fmh_keys[0]) ||
> > @@ -727,7 +799,10 @@ xfs_getfsmap(
> >  	/* Set up our device handlers. */
> >  	memset(handlers, 0, sizeof(handlers));
> >  	handlers[0].dev = new_encode_dev(mp->m_ddev_targp->bt_dev);
> > -	handlers[0].fn = xfs_getfsmap_datadev_rmapbt;
> > +	if (xfs_sb_version_hasrmapbt(&mp->m_sb))
> > +		handlers[0].fn = xfs_getfsmap_datadev_rmapbt;
> > +	else
> > +		handlers[0].fn = xfs_getfsmap_datadev_bnobt;
> >  	if (mp->m_logdev_targp != mp->m_ddev_targp) {
> >  		handlers[1].dev = new_encode_dev(mp->m_logdev_targp->bt_dev);
> >  		handlers[1].fn = xfs_getfsmap_logdev;
> > 
> > --
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