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

To: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
Subject: Re: [PATCH 028/119] xfs: define the on-disk rmap btree format
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 6 Jul 2016 14:05:55 +1000
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, vishal.l.verma@xxxxxxxxx, xfs@xxxxxxxxxxx, Dave Chinner <dchinner@xxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <146612645206.12839.17008642336898856662.stgit@xxxxxxxxxxxxxxxx>
References: <146612627129.12839.3827886950949809165.stgit@xxxxxxxxxxxxxxxx> <146612645206.12839.17008642336898856662.stgit@xxxxxxxxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Thu, Jun 16, 2016 at 06:20:52PM -0700, Darrick J. Wong wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> 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@xxxxxxxxxxxxx

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