Re: [PATCH 1/3] xfs: Introduce xfs_iext_max() helper

[Chandan Babu R <chandanrlinux@gmail.com>]

On Tuesday 1 September 2020 2:13:40 AM IST Darrick J. Wong wrote:
> On Mon, Aug 31, 2020 at 06:30:08PM +0530, Chandan Babu R wrote:
> > xfs_iext_max() returns the maximum number of extents possible for either
> > data fork or attribute fork. This helper will be extended further in a
> > future commit when maximum extent counts associated with data/attribute
> > forks are increased.
> > 
> > No functional changes have been made.
> 
> Hmm....
> 
> > Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
> > ---
> >  fs/xfs/libxfs/xfs_bmap.c       |  9 ++++-----
> >  fs/xfs/libxfs/xfs_inode_buf.c  |  8 +++-----
> >  fs/xfs/libxfs/xfs_inode_fork.h | 10 ++++++++++
> >  3 files changed, 17 insertions(+), 10 deletions(-)
> > 
> > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> > index dcc8eeecd571..16b983b8977d 100644
> > --- a/fs/xfs/libxfs/xfs_bmap.c
> > +++ b/fs/xfs/libxfs/xfs_bmap.c
> > @@ -74,13 +74,12 @@ xfs_bmap_compute_maxlevels(
> >  	 * for both ATTR1 and ATTR2 we have to assume the worst case scenario
> >  	 * of a minimum size available.
> >  	 */
> > -	if (whichfork == XFS_DATA_FORK) {
> > -		maxleafents = MAXEXTNUM;
> > +	maxleafents = xfs_iext_max(&mp->m_sb, whichfork);
> > +	if (whichfork == XFS_DATA_FORK)
> >  		sz = XFS_BMDR_SPACE_CALC(MINDBTPTRS);
> > -	} else {
> > -		maxleafents = MAXAEXTNUM;
> > +	else
> >  		sz = XFS_BMDR_SPACE_CALC(MINABTPTRS);
> > -	}
> > +
> >  	maxrootrecs = xfs_bmdr_maxrecs(sz, 0);
> >  	minleafrecs = mp->m_bmap_dmnr[0];
> >  	minnoderecs = mp->m_bmap_dmnr[1];
> > diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
> > index 8d5dd08eab75..5dcd71bfab2e 100644
> > --- a/fs/xfs/libxfs/xfs_inode_buf.c
> > +++ b/fs/xfs/libxfs/xfs_inode_buf.c
> > @@ -369,6 +369,7 @@ xfs_dinode_verify_fork(
> >  	int			whichfork)
> >  {
> >  	uint32_t		di_nextents = XFS_DFORK_NEXTENTS(dip, whichfork);
> > +	xfs_extnum_t		max_extents;
> >  
> >  	switch (XFS_DFORK_FORMAT(dip, whichfork)) {
> >  	case XFS_DINODE_FMT_LOCAL:
> > @@ -390,12 +391,9 @@ xfs_dinode_verify_fork(
> >  			return __this_address;
> >  		break;
> >  	case XFS_DINODE_FMT_BTREE:
> > -		if (whichfork == XFS_ATTR_FORK) {
> > -			if (di_nextents > MAXAEXTNUM)
> > -				return __this_address;
> > -		} else if (di_nextents > MAXEXTNUM) {
> > +		max_extents = xfs_iext_max(&mp->m_sb, whichfork);
> > +		if (di_nextents > max_extents)
> >  			return __this_address;
> > -		}
> >  		break;
> >  	default:
> >  		return __this_address;
> > diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> > index 4219b01f1034..75e07078967e 100644
> > --- a/fs/xfs/libxfs/xfs_inode_fork.h
> > +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> > @@ -153,6 +153,16 @@ static inline int8_t xfs_ifork_format(struct xfs_ifork *ifp)
> >  	return ifp->if_format;
> >  }
> >  
> > +static inline xfs_extnum_t xfs_iext_max(struct xfs_sb *sbp, int whichfork)
> > +{
> > +	ASSERT(whichfork == XFS_DATA_FORK || whichfork == XFS_ATTR_FORK);
> > +
> > +	if (whichfork == XFS_DATA_FORK)
> > +		return MAXEXTNUM;
> > +	else
> > +		return MAXAEXTNUM;
> 
> ...I kinda wish you /had/ made the functional change to make this return
> MAXEXTNUM for cow forks, even if none of the callers actually care. :)

Ok. I will include that change in the next version.

> 
> --D
> 
> > +}
> > +
> >  struct xfs_ifork *xfs_iext_state_to_fork(struct xfs_inode *ip, int state);
> >  
> >  int		xfs_iformat_data_fork(struct xfs_inode *, struct xfs_dinode *);
> 


-- 
chandan