Re: [PATCH 026/119] xfs: add owner field to extent allocation and freeing

Dave Chinner
2016-07-06T04:01:44Z

On Thu, Jun 16, 2016 at 06:20:39PM -0700, Darrick J. Wong wrote:
> For the rmap btree to work, we have to feed the extent owner
> information to the the allocation and freeing functions. This
> information is what will end up in the rmap btree that tracks
> allocated extents. While we technically don't need the owner
> information when freeing extents, passing it allows us to validate
> that the extent we are removing from the rmap btree actually
> belonged to the owner we expected it to belong to.
....

> --- a/fs/xfs/libxfs/xfs_format.h
> +++ b/fs/xfs/libxfs/xfs_format.h
> @@ -1318,6 +1318,71 @@ typedef __be32 xfs_inobt_ptr_t;
> */
> #define XFS_RMAP_CRC_MAGIC 0x524d4233 /* 'RMB3' */
>
> +/*
> + * Ownership info for an extent. This is used to create reverse-mapping
> + * entries.
> + */
> +#define XFS_OWNER_INFO_ATTR_FORK (1 << 0)
> +#define XFS_OWNER_INFO_BMBT_BLOCK (1 << 1)
> +struct xfs_owner_info {
> + uint64_t oi_owner;
> + xfs_fileoff_t oi_offset;
> + unsigned int oi_flags;
> +};
> +
> +static inline void
> +xfs_rmap_ag_owner(
> + struct xfs_owner_info *oi,
> + uint64_t owner)
> +{
> + oi->oi_owner = owner;
> + oi->oi_offset = 0;
> + oi->oi_flags = 0;
> +}
> +
> +static inline void
> +xfs_rmap_ino_bmbt_owner(
> + struct xfs_owner_info *oi,
> + xfs_ino_t ino,
> + int whichfork)
> +{
> + oi->oi_owner = ino;
> + oi->oi_offset = 0;
> + oi->oi_flags = XFS_OWNER_INFO_BMBT_BLOCK;
> + if (whichfork == XFS_ATTR_FORK)
> + oi->oi_flags |= XFS_OWNER_INFO_ATTR_FORK;
> +}
> +
> +static inline void
> +xfs_rmap_ino_owner(
> + struct xfs_owner_info *oi,
> + xfs_ino_t ino,
> + int whichfork,
> + xfs_fileoff_t offset)
> +{
> + oi->oi_owner = ino;
> + oi->oi_offset = offset;
> + oi->oi_flags = 0;
> + if (whichfork == XFS_ATTR_FORK)
> + oi->oi_flags |= XFS_OWNER_INFO_ATTR_FORK;
> +}

One of the things we've avaoided doing so far is putting functions
like this into xfs_format.h. xfs_format.h is really just for the
on disk format definitions, not the code to access/pack/unpack it.
Hence I think think these sorts of functions need to be moved to
xfs_rmap.h....

Cheers,

Dave.

--
Dave Chinner
david@fromorbit.com