[PATCH 028/119] xfs: define the on-disk rmap btree format

[Darrick J. Wong]

On Wed, Jul 06, 2016 at 02:05:55PM +1000, Dave Chinner wrote:
> On Thu, Jun 16, 2016 at 06:20:52PM -0700, Darrick J. Wong wrote:
> > From: Dave Chinner <dchinner at redhat.com>
> > 
> > Now we have all the surrounding call infrastructure in place, we can
> > start filling out the rmap btree implementation. Start with the
> > on-disk btree format; add everything needed to read, write and
> > manipulate rmap btree blocks. This prepares the way for adding the
> > btree operations implementation.
> > 
> > [darrick: record owner and offset info in rmap btree]
> > [darrick: fork, bmbt and unwritten state in rmap btree]
> > [darrick: flags are a separate field in xfs_rmap_irec]
> > [darrick: calculate maxlevels separately]
> > [darrick: move the 'unwritten' bit into unused parts of rm_offset]
> .....
> > diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> > index 97f354f..6efc7a3 100644
> > --- a/fs/xfs/libxfs/xfs_format.h
> > +++ b/fs/xfs/libxfs/xfs_format.h
> > @@ -1383,11 +1383,151 @@ xfs_rmap_ino_owner(
> >  #define XFS_RMAP_OWN_INODES	(-7ULL)	/* Inode chunk */
> >  #define XFS_RMAP_OWN_MIN	(-8ULL) /* guard */
> >  
> > +#define XFS_RMAP_NON_INODE_OWNER(owner)	(!!((owner) & (1ULL << 63)))
> > +
> > +/*
> > + * Data record structure
> > + */
> > +struct xfs_rmap_rec {
> > +	__be32		rm_startblock;	/* extent start block */
> > +	__be32		rm_blockcount;	/* extent length */
> > +	__be64		rm_owner;	/* extent owner */
> > +	__be64		rm_offset;	/* offset within the owner */
> > +};
> > +
> > +/*
> > + * rmap btree record
> > + *  rm_offset:63 is the attribute fork flag
> > + *  rm_offset:62 is the bmbt block flag
> > + *  rm_offset:61 is the unwritten extent flag (same as l0:63 in bmbt)
> > + *  rm_offset:54-60 aren't used and should be zero
> > + *  rm_offset:0-53 is the block offset within the inode
> > + */
> > +#define XFS_RMAP_OFF_ATTR_FORK	((__uint64_t)1ULL << 63)
> > +#define XFS_RMAP_OFF_BMBT_BLOCK	((__uint64_t)1ULL << 62)
> > +#define XFS_RMAP_OFF_UNWRITTEN	((__uint64_t)1ULL << 61)
> > +
> > +#define XFS_RMAP_LEN_MAX	((__uint32_t)~0U)
> > +#define XFS_RMAP_OFF_FLAGS	(XFS_RMAP_OFF_ATTR_FORK | \
> > +				 XFS_RMAP_OFF_BMBT_BLOCK | \
> > +				 XFS_RMAP_OFF_UNWRITTEN)
> > +#define XFS_RMAP_OFF_MASK	((__uint64_t)0x3FFFFFFFFFFFFFULL)
> > +
> > +#define XFS_RMAP_OFF(off)		((off) & XFS_RMAP_OFF_MASK)
> > +
> > +#define XFS_RMAP_IS_BMBT_BLOCK(off)	(!!((off) & XFS_RMAP_OFF_BMBT_BLOCK))
> > +#define XFS_RMAP_IS_ATTR_FORK(off)	(!!((off) & XFS_RMAP_OFF_ATTR_FORK))
> > +#define XFS_RMAP_IS_UNWRITTEN(len)	(!!((off) & XFS_RMAP_OFF_UNWRITTEN))
> > +
> > +#define RMAPBT_STARTBLOCK_BITLEN	32
> > +#define RMAPBT_BLOCKCOUNT_BITLEN	32
> > +#define RMAPBT_OWNER_BITLEN		64
> > +#define RMAPBT_ATTRFLAG_BITLEN		1
> > +#define RMAPBT_BMBTFLAG_BITLEN		1
> > +#define RMAPBT_EXNTFLAG_BITLEN		1
> > +#define RMAPBT_UNUSED_OFFSET_BITLEN	7
> > +#define RMAPBT_OFFSET_BITLEN		54
> > +
> > +#define XFS_RMAP_ATTR_FORK		(1 << 0)
> > +#define XFS_RMAP_BMBT_BLOCK		(1 << 1)
> > +#define XFS_RMAP_UNWRITTEN		(1 << 2)
> > +#define XFS_RMAP_KEY_FLAGS		(XFS_RMAP_ATTR_FORK | \
> > +					 XFS_RMAP_BMBT_BLOCK)
> > +#define XFS_RMAP_REC_FLAGS		(XFS_RMAP_UNWRITTEN)
> > +struct xfs_rmap_irec {
> > +	xfs_agblock_t	rm_startblock;	/* extent start block */
> > +	xfs_extlen_t	rm_blockcount;	/* extent length */
> > +	__uint64_t	rm_owner;	/* extent owner */
> > +	__uint64_t	rm_offset;	/* offset within the owner */
> > +	unsigned int	rm_flags;	/* state flags */
> > +};
> 
> Same as my last comment about xfs_format.h. Up to here is all good -
> they are format definitions. But these:
> 
> > +
> > +static inline __u64
> > +xfs_rmap_irec_offset_pack(
> > +	const struct xfs_rmap_irec	*irec)
> > +{
> > +	__u64			x;
> > +
> > +	x = XFS_RMAP_OFF(irec->rm_offset);
> > +	if (irec->rm_flags & XFS_RMAP_ATTR_FORK)
> > +		x |= XFS_RMAP_OFF_ATTR_FORK;
> > +	if (irec->rm_flags & XFS_RMAP_BMBT_BLOCK)
> > +		x |= XFS_RMAP_OFF_BMBT_BLOCK;
> > +	if (irec->rm_flags & XFS_RMAP_UNWRITTEN)
> > +		x |= XFS_RMAP_OFF_UNWRITTEN;
> > +	return x;
> > +}
> > +
> > +static inline int
> > +xfs_rmap_irec_offset_unpack(
> > +	__u64			offset,
> > +	struct xfs_rmap_irec	*irec)
> > +{
> > +	if (offset & ~(XFS_RMAP_OFF_MASK | XFS_RMAP_OFF_FLAGS))
> > +		return -EFSCORRUPTED;
> > +	irec->rm_offset = XFS_RMAP_OFF(offset);
> > +	if (offset & XFS_RMAP_OFF_ATTR_FORK)
> > +		irec->rm_flags |= XFS_RMAP_ATTR_FORK;
> > +	if (offset & XFS_RMAP_OFF_BMBT_BLOCK)
> > +		irec->rm_flags |= XFS_RMAP_BMBT_BLOCK;
> > +	if (offset & XFS_RMAP_OFF_UNWRITTEN)
> > +		irec->rm_flags |= XFS_RMAP_UNWRITTEN;
> > +	return 0;
> > +}
> 
> And these:
> 
> > +static inline void
> > +xfs_owner_info_unpack(
> > +	struct xfs_owner_info	*oinfo,
> > +	uint64_t		*owner,
> > +	uint64_t		*offset,
> > +	unsigned int		*flags)
> > +{
> > +	unsigned int		r = 0;
> > +
> > +	*owner = oinfo->oi_owner;
> > +	*offset = oinfo->oi_offset;
> > +	if (oinfo->oi_flags & XFS_OWNER_INFO_ATTR_FORK)
> > +		r |= XFS_RMAP_ATTR_FORK;
> > +	if (oinfo->oi_flags & XFS_OWNER_INFO_BMBT_BLOCK)
> > +		r |= XFS_RMAP_BMBT_BLOCK;
> > +	*flags = r;
> > +}
> > +
> > +static inline void
> > +xfs_owner_info_pack(
> > +	struct xfs_owner_info	*oinfo,
> > +	uint64_t		owner,
> > +	uint64_t		offset,
> > +	unsigned int		flags)
> > +{
> > +	oinfo->oi_owner = owner;
> > +	oinfo->oi_offset = XFS_RMAP_OFF(offset);
> > +	oinfo->oi_flags = 0;
> > +	if (flags & XFS_RMAP_ATTR_FORK)
> > +		oinfo->oi_flags |= XFS_OWNER_INFO_ATTR_FORK;
> > +	if (flags & XFS_RMAP_BMBT_BLOCK)
> > +		oinfo->oi_flags |= XFS_OWNER_INFO_BMBT_BLOCK;
> > +}
> > +
> 
> really belong in xfs_rmap.h or xfs_rmap_btree.h.

Yep.  I think these'll end up in xfs_rmap_btree.h.

--D

> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david at fromorbit.com