Re: [PATCH 006/119] xfs: port differences from xfsprogs libxfs

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

On Mon, Jun 20, 2016 at 10:21:07AM +1000, Dave Chinner wrote:
> On Thu, Jun 16, 2016 at 06:18:30PM -0700, Darrick J. Wong wrote:
> > Port various differences between xfsprogs and the kernel.  This
> > cleans up both so that we can develop rmap and reflink on the
> > same libxfs code.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Nak. I'm essentially trying to keep the little hacks needed in 
> userspace out of the kernel libxfs tree. We quite regularly get
> people scanning the kernel tree and trying to remove things like
> exported function prototypes that are not used in kernel space,
> so the headers in userspace carry those simply to prevent people
> continually sending kernel patches that we have to look at and then
> ignore...

Fair enough, I merely diff'd the two libxfs and figured I'd remove
all the differences to try to develop atop as close to identical libxfs as I
could get. :)

> > diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> > index 99b077c..58bdca7 100644
> > --- a/fs/xfs/libxfs/xfs_alloc.c
> > +++ b/fs/xfs/libxfs/xfs_alloc.c
> > @@ -2415,7 +2415,9 @@ xfs_alloc_read_agf(
> >  			be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNTi]);
> >  		spin_lock_init(&pag->pagb_lock);
> >  		pag->pagb_count = 0;
> > +#ifdef __KERNEL__
> >  		pag->pagb_tree = RB_ROOT;
> > +#endif
> >  		pag->pagf_init = 1;
> >  	}
> >  #ifdef DEBUG
> 
> e.g. this is an indication that reminds us that there is
> functionality in the libxfs kernel tree that isn't in userspace...
> 
> > diff --git a/fs/xfs/libxfs/xfs_attr_leaf.h b/fs/xfs/libxfs/xfs_attr_leaf.h
> > index 4f2aed0..8ef420a 100644
> > --- a/fs/xfs/libxfs/xfs_attr_leaf.h
> > +++ b/fs/xfs/libxfs/xfs_attr_leaf.h
> > @@ -51,7 +51,7 @@ int	xfs_attr_shortform_getvalue(struct xfs_da_args *args);
> >  int	xfs_attr_shortform_to_leaf(struct xfs_da_args *args);
> >  int	xfs_attr_shortform_remove(struct xfs_da_args *args);
> >  int	xfs_attr_shortform_allfit(struct xfs_buf *bp, struct xfs_inode *dp);
> > -int	xfs_attr_shortform_bytesfit(xfs_inode_t *dp, int bytes);
> > +int	xfs_attr_shortform_bytesfit(struct xfs_inode *dp, int bytes);
> >  void	xfs_attr_fork_remove(struct xfs_inode *ip, struct xfs_trans *tp);
> 
> Things like this are fine...

Ok.

> >  
> >  /*
> > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> > index 932381c..499e980 100644
> > --- a/fs/xfs/libxfs/xfs_bmap.c
> > +++ b/fs/xfs/libxfs/xfs_bmap.c
> > @@ -1425,7 +1425,7 @@ xfs_bmap_search_multi_extents(
> >   * Else, *lastxp will be set to the index of the found
> >   * entry; *gotp will contain the entry.
> >   */
> > -STATIC xfs_bmbt_rec_host_t *                 /* pointer to found extent entry */
> > +xfs_bmbt_rec_host_t *                 /* pointer to found extent entry */
> >  xfs_bmap_search_extents(
> >  	xfs_inode_t     *ip,            /* incore inode pointer */
> >  	xfs_fileoff_t   bno,            /* block number searched for */
> > diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
> > index 423a34e..79e3ebe 100644
> > --- a/fs/xfs/libxfs/xfs_bmap.h
> > +++ b/fs/xfs/libxfs/xfs_bmap.h
> > @@ -231,4 +231,10 @@ int	xfs_bmap_shift_extents(struct xfs_trans *tp, struct xfs_inode *ip,
> >  		int num_exts);
> >  int	xfs_bmap_split_extent(struct xfs_inode *ip, xfs_fileoff_t split_offset);
> >  
> > +struct xfs_bmbt_rec_host *
> > +	xfs_bmap_search_extents(struct xfs_inode *ip, xfs_fileoff_t bno,
> > +				int fork, int *eofp, xfs_extnum_t *lastxp,
> > +				struct xfs_bmbt_irec *gotp,
> > +				struct xfs_bmbt_irec *prevp);
> > +
> >  #endif	/* __XFS_BMAP_H__ */
> 
> But these are the sort of "clean up the kernel patches" that I was
> refering to. If there's a user in kernel space, then fine, otherwise
> it doesn't hurt to keep it only in userspace. There are relatively
> few of these....
> 
> > diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
> > index 1f88e1c..105979d 100644
> > --- a/fs/xfs/libxfs/xfs_btree.c
> > +++ b/fs/xfs/libxfs/xfs_btree.c
> > @@ -2532,6 +2532,7 @@ error0:
> >  	return error;
> >  }
> >  
> > +#ifdef __KERNEL__
> >  struct xfs_btree_split_args {
> >  	struct xfs_btree_cur	*cur;
> >  	int			level;
> > @@ -2609,6 +2610,9 @@ xfs_btree_split(
> >  	destroy_work_on_stack(&args.work);
> >  	return args.result;
> >  }
> > +#else /* !KERNEL */
> > +#define xfs_btree_split	__xfs_btree_split
> > +#endif
> 
> Same again -this is 4 lines of code that is userspace only. It's a
> tiny amount compared to the original difference that these
> kernel-only stack splits required, and so not a huge issue.

Will drop these two.

> > --- a/fs/xfs/libxfs/xfs_dquot_buf.c
> > +++ b/fs/xfs/libxfs/xfs_dquot_buf.c
> > @@ -31,10 +31,16 @@
> >  #include "xfs_cksum.h"
> >  #include "xfs_trace.h"
> >  
> > +/*
> > + * XXX: kernel implementation causes ndquots calc to go real
> > + * bad. Just leaving the existing userspace calc here right now.
> > + */
> >  int
> >  xfs_calc_dquots_per_chunk(
> >  	unsigned int		nbblks)	/* basic block units */
> >  {
> > +#ifdef __KERNEL__
> > +	/* kernel code that goes wrong in userspace! */
> >  	unsigned int	ndquots;
> >  
> >  	ASSERT(nbblks > 0);
> > @@ -42,6 +48,10 @@ xfs_calc_dquots_per_chunk(
> >  	do_div(ndquots, sizeof(xfs_dqblk_t));
> >  
> >  	return ndquots;
> > +#else
> > +	ASSERT(nbblks > 0);
> > +	return BBTOB(nbblks) / sizeof(xfs_dqblk_t);
> > +#endif
> >  }
> 
> This is a clear case that we need to fix the code to be
> correct for both kernel and userspace without modification, not
> propagate the userspace hack back into the kernel code.

I /think/ it does this because libxfs/libxfs_priv.h's __do_div expects
to be passed a pointer to an unsigned long long (which is later dereferenced
and used as an unsigned long), whereas ndquots is an int?

I'm not sure why we need do_div either, since AFAICT we only ever process
quota in chunks of 1FSB, for which 32-bit division should be fine.

> > diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
> > index 9d9559e..794fa66 100644
> > --- a/fs/xfs/libxfs/xfs_inode_buf.c
> > +++ b/fs/xfs/libxfs/xfs_inode_buf.c
> > @@ -56,6 +56,17 @@ xfs_inobp_check(
> >  }
> >  #endif
> >  
> > +bool
> > +xfs_dinode_good_version(
> > +	struct xfs_mount *mp,
> > +	__u8		version)
> > +{
> > +	if (xfs_sb_version_hascrc(&mp->m_sb))
> > +		return version == 3;
> > +
> > +	return version == 1 || version == 2;
> > +}
> 
> This xfs_dinode_good_version() change needs to be a separate patch

Ok.

> >  void	xfs_inobp_check(struct xfs_mount *, struct xfs_buf *);
> >  #else
> > diff --git a/fs/xfs/libxfs/xfs_log_format.h b/fs/xfs/libxfs/xfs_log_format.h
> > index e8f49c0..e5baba3 100644
> > --- a/fs/xfs/libxfs/xfs_log_format.h
> > +++ b/fs/xfs/libxfs/xfs_log_format.h
> > @@ -462,8 +462,8 @@ static inline uint xfs_log_dinode_size(int version)
> >  typedef struct xfs_buf_log_format {
> >  	unsigned short	blf_type;	/* buf log item type indicator */
> >  	unsigned short	blf_size;	/* size of this item */
> > -	ushort		blf_flags;	/* misc state */
> > -	ushort		blf_len;	/* number of blocks in this buf */
> > +	unsigned short	blf_flags;	/* misc state */
> > +	unsigned short	blf_len;	/* number of blocks in this buf */
> >  	__int64_t	blf_blkno;	/* starting blkno of this buf */
> >  	unsigned int	blf_map_size;	/* used size of data bitmap in words */
> >  	unsigned int	blf_data_map[XFS_BLF_DATAMAP_SIZE]; /* dirty bitmap */
> 
> The removal of ushort/uint from the kernel code needs to be a
> separate patch that addresses all the users, not just the couple in
> shared headers....

Ok.

> > diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
> > index 12ca867..09d6fd0 100644
> > --- a/fs/xfs/libxfs/xfs_sb.c
> > +++ b/fs/xfs/libxfs/xfs_sb.c
> > @@ -261,6 +261,7 @@ xfs_mount_validate_sb(
> >  	/*
> >  	 * Until this is fixed only page-sized or smaller data blocks work.
> >  	 */
> > +#ifdef __KERNEL__
> >  	if (unlikely(sbp->sb_blocksize > PAGE_SIZE)) {
> >  		xfs_warn(mp,
> >  		"File system with blocksize %d bytes. "
> > @@ -268,6 +269,7 @@ xfs_mount_validate_sb(
> >  				sbp->sb_blocksize, PAGE_SIZE);
> >  		return -ENOSYS;
> >  	}
> > +#endif
> >  
> >  	/*
> >  	 * Currently only very few inode sizes are supported.
> > @@ -291,10 +293,12 @@ xfs_mount_validate_sb(
> >  		return -EFBIG;
> >  	}
> >  
> > +#ifdef __KERNEL__
> >  	if (check_inprogress && sbp->sb_inprogress) {
> >  		xfs_warn(mp, "Offline file system operation in progress!");
> >  		return -EFSCORRUPTED;
> >  	}
> > +#endif
> >  	return 0;
> >  }
> 
> Again, I don't think this needs to be propagated back into the
> kernel code...

Will drop.

--D
> 
> -- 
> Dave Chinner
> david@fromorbit.com