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

Darrick J. Wong
2016-07-06T06:45:10Z

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@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@fromorbit.com