On Mon, Nov 14, 2016 at 06:12:32PM +0100, Christoph Hellwig wrote:
> xfs_iext_lookup_extent looks up a single extent at the passed in offset,
> and returns the extent covering the area, or the one behind it in case
> of a hole, as well as the index of the returned extent in arguments,
> as well as a simple bool as return value that is set to false if no
> extent could be found because the offset is behind EOF. It is a simpler
> replacement for xfs_bmap_search_extent that leaves looking up the rarely
> needed previous extent to the caller and has a nicer calling convention.
>
> xfs_iext_get_extent is a helper for iterating over the extent list,
> it takes an extent index as input, and returns the extent at that index
> in it's expanded form in an argument if it exists. The actual return
> value is a bool whether the index is valid or not.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/xfs/libxfs/xfs_inode_fork.c | 46 ++++++++++++++++++++++++++++++++++++++++++
> fs/xfs/libxfs/xfs_inode_fork.h | 6 ++++++
> 2 files changed, 52 insertions(+)
>
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index 5fbe24c..749fbfb 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -2003,3 +2003,49 @@ xfs_ifork_init_cow(
> ip->i_cformat = XFS_DINODE_FMT_EXTENTS;
> ip->i_cnextents = 0;
> }
> +
> +/*
> + * Lookup the extent covering bno.
> + *
> + * If there is an extent covering bno return the extent index, and store the
> + * expanded extent structure in *gotp, and the extent indes in *idx.
Typo: index
Otherwise looks good:
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> + * If there is no extent covering bno, but there is an extent after it (e.g.
> + * it lies in a hole) return that extent in *gotp and its index in *idx
> + * instead.
> + * If bno is beyond the last extent return false, and return the index after
> + * the last valid index in *idxp.
> + */
> +bool
> +xfs_iext_lookup_extent(
> + struct xfs_inode *ip,
> + struct xfs_ifork *ifp,
> + xfs_fileoff_t bno,
> + xfs_extnum_t *idxp,
> + struct xfs_bmbt_irec *gotp)
> +{
> + struct xfs_bmbt_rec_host *ep;
> +
> + XFS_STATS_INC(ip->i_mount, xs_look_exlist);
> +
> + ep = xfs_iext_bno_to_ext(ifp, bno, idxp);
> + if (!ep)
> + return false;
> + xfs_bmbt_get_all(ep, gotp);
> + return true;
> +}
> +
> +/*
> + * Return true if there is an extent at index idx, and return the expanded
> + * extent structure at idx in that case. Else return false.
> + */
> +bool
> +xfs_iext_get_extent(
> + struct xfs_ifork *ifp,
> + xfs_extnum_t idx,
> + struct xfs_bmbt_irec *gotp)
> +{
> + if (idx < 0 || idx >= xfs_iext_count(ifp))
> + return false;
> + xfs_bmbt_get_all(xfs_iext_get_ext(ifp, idx), gotp);
> + return true;
> +}
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index 8bf112e..7fb8365 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -182,6 +182,12 @@ void xfs_iext_irec_compact_pages(struct xfs_ifork *);
> void xfs_iext_irec_compact_full(struct xfs_ifork *);
> void xfs_iext_irec_update_extoffs(struct xfs_ifork *, int, int);
>
> +bool xfs_iext_lookup_extent(struct xfs_inode *ip,
> + struct xfs_ifork *ifp, xfs_fileoff_t bno,
> + xfs_extnum_t *idxp, struct xfs_bmbt_irec *gotp);
> +bool xfs_iext_get_extent(struct xfs_ifork *ifp, xfs_extnum_t idx,
> + struct xfs_bmbt_irec *gotp);
> +
> extern struct kmem_zone *xfs_ifork_zone;
>
> extern void xfs_ifork_init_cow(struct xfs_inode *ip);
> --
> 2.1.4
>
> --
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