Re: [PATCH v4 01/11] xfs: track active state of allocation btree cursors

[Brian Foster <bfoster@redhat.com>]

On Wed, Sep 18, 2019 at 11:38:18AM -0700, Darrick J. Wong wrote:
> On Mon, Sep 16, 2019 at 08:16:25AM -0400, Brian Foster wrote:
> > The upcoming allocation algorithm update searches multiple
> > allocation btree cursors concurrently. As such, it requires an
> > active state to track when a particular cursor should continue
> > searching. While active state will be modified based on higher level
> > logic, we can define base functionality based on the result of
> > allocation btree lookups.
> > 
> > Define an active flag in the private area of the btree cursor.
> > Update it based on the result of lookups in the existing allocation
> > btree helpers. Finally, provide a new helper to query the current
> > state.
> > 
> > Signed-off-by: Brian Foster <bfoster@redhat.com>
> > ---
> >  fs/xfs/libxfs/xfs_alloc.c       | 24 +++++++++++++++++++++---
> >  fs/xfs/libxfs/xfs_alloc_btree.c |  1 +
> >  fs/xfs/libxfs/xfs_btree.h       |  3 +++
> >  3 files changed, 25 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> > index 533b04aaf6f6..512a45888e06 100644
> > --- a/fs/xfs/libxfs/xfs_alloc.c
> > +++ b/fs/xfs/libxfs/xfs_alloc.c
> > @@ -146,9 +146,13 @@ xfs_alloc_lookup_eq(
> >  	xfs_extlen_t		len,	/* length of extent */
> >  	int			*stat)	/* success/failure */
> >  {
> > +	int			error;
> > +
> >  	cur->bc_rec.a.ar_startblock = bno;
> >  	cur->bc_rec.a.ar_blockcount = len;
> > -	return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
> > +	error = xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
> > +	cur->bc_private.a.priv.abt.active = *stat == 1 ? true : false;
> 
> I think "cur->bc_private.a.priv.abt.active = (*stat == 1);" would have
> sufficed for these, right?  (Yeah, sorry, picking at nits here...)
> 

Sure, I'll fix those up.

Brian

> --D
> 
> > +	return error;
> >  }
> >  
> >  /*
> > @@ -162,9 +166,13 @@ xfs_alloc_lookup_ge(
> >  	xfs_extlen_t		len,	/* length of extent */
> >  	int			*stat)	/* success/failure */
> >  {
> > +	int			error;
> > +
> >  	cur->bc_rec.a.ar_startblock = bno;
> >  	cur->bc_rec.a.ar_blockcount = len;
> > -	return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
> > +	error = xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
> > +	cur->bc_private.a.priv.abt.active = *stat == 1 ? true : false;
> > +	return error;
> >  }
> >  
> >  /*
> > @@ -178,9 +186,19 @@ xfs_alloc_lookup_le(
> >  	xfs_extlen_t		len,	/* length of extent */
> >  	int			*stat)	/* success/failure */
> >  {
> > +	int			error;
> >  	cur->bc_rec.a.ar_startblock = bno;
> >  	cur->bc_rec.a.ar_blockcount = len;
> > -	return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
> > +	error = xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
> > +	cur->bc_private.a.priv.abt.active = *stat == 1 ? true : false;
> > +	return error;
> > +}
> > +
> > +static inline bool
> > +xfs_alloc_cur_active(
> > +	struct xfs_btree_cur	*cur)
> > +{
> > +	return cur && cur->bc_private.a.priv.abt.active;
> >  }
> >  
> >  /*
> > diff --git a/fs/xfs/libxfs/xfs_alloc_btree.c b/fs/xfs/libxfs/xfs_alloc_btree.c
> > index 2a94543857a1..279694d73e4e 100644
> > --- a/fs/xfs/libxfs/xfs_alloc_btree.c
> > +++ b/fs/xfs/libxfs/xfs_alloc_btree.c
> > @@ -507,6 +507,7 @@ xfs_allocbt_init_cursor(
> >  
> >  	cur->bc_private.a.agbp = agbp;
> >  	cur->bc_private.a.agno = agno;
> > +	cur->bc_private.a.priv.abt.active = false;
> >  
> >  	if (xfs_sb_version_hascrc(&mp->m_sb))
> >  		cur->bc_flags |= XFS_BTREE_CRC_BLOCKS;
> > diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
> > index ced1e65d1483..b4e3ec1d7ff9 100644
> > --- a/fs/xfs/libxfs/xfs_btree.h
> > +++ b/fs/xfs/libxfs/xfs_btree.h
> > @@ -183,6 +183,9 @@ union xfs_btree_cur_private {
> >  		unsigned long	nr_ops;		/* # record updates */
> >  		int		shape_changes;	/* # of extent splits */
> >  	} refc;
> > +	struct {
> > +		bool		active;		/* allocation cursor state */
> > +	} abt;
> >  };
> >  
> >  /*
> > -- 
> > 2.20.1
> >