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

[Dave Chinner]

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.

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com