On Mon, Oct 23, 2017 at 08:30:17AM +0200, Christoph Hellwig wrote:
> This helper looks up the last extent the covers space before the passed
> in block number. This is useful for truncate and similar operations that
> operate backwards over the extent list. For xfs_bunmapi it also is
> a slight optimization as we can return early if there are not extents
> at or below the end of the to be truncated range.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_bmap.c | 27 +++++++--------------------
> fs/xfs/libxfs/xfs_inode_fork.c | 21 +++++++++++++++++++++
> fs/xfs/libxfs/xfs_inode_fork.h | 4 ++++
> fs/xfs/xfs_reflink.c | 19 +++++++------------
> 4 files changed, 39 insertions(+), 32 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 53ff6d92b532..b26c4ece7cbe 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -1380,17 +1380,8 @@ xfs_bmap_last_before(
> return error;
> }
>
> - if (xfs_iext_lookup_extent(ip, ifp, *last_block - 1, &idx, &got)) {
> - if (got.br_startoff <= *last_block - 1)
> - return 0;
> - }
> -
> - if (xfs_iext_get_extent(ifp, idx - 1, &got)) {
> - *last_block = got.br_startoff + got.br_blockcount;
> - return 0;
> - }
> -
> - *last_block = 0;
> + if (!xfs_iext_lookup_extent_before(ip, ifp, last_block, &idx, &got))
> + *last_block = 0;
> return 0;
> }
>
> @@ -5154,17 +5145,13 @@ __xfs_bunmapi(
> }
> XFS_STATS_INC(mp, xs_blk_unmap);
> isrt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(ip);
> - end = start + len - 1;
> + end = start + len;
>
> - /*
> - * Check to see if the given block number is past the end of the
> - * file, back up to the last block if so...
> - */
> - if (!xfs_iext_lookup_extent(ip, ifp, end, &lastx, &got)) {
> - ASSERT(lastx > 0);
> - xfs_iext_get_extent(ifp, --lastx, &got);
> - end = got.br_startoff + got.br_blockcount - 1;
> + if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &lastx, &got)) {
> + *rlen = 0;
> + return 0;
> }
> + end--;
>
> logflags = 0;
> if (ifp->if_flags & XFS_IFBROOT) {
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index c70f9ef07b6d..5b90f912e41a 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -1960,6 +1960,27 @@ xfs_iext_lookup_extent(
> return true;
> }
>
> +/*
> + * Returns the last extent before end, and if this extent doesn't cover
> + * end, update end to the end of the extent.
> + */
> +bool
> +xfs_iext_lookup_extent_before(
> + struct xfs_inode *ip,
> + struct xfs_ifork *ifp,
> + xfs_fileoff_t *end,
> + xfs_extnum_t *idxp,
> + struct xfs_bmbt_irec *gotp)
> +{
> + if (xfs_iext_lookup_extent(ip, ifp, *end - 1, idxp, gotp) &&
> + gotp->br_startoff <= *end - 1)
> + return true;
> + if (!xfs_iext_get_extent(ifp, --*idxp, gotp))
> + return false;
> + *end = gotp->br_startoff + gotp->br_blockcount;
> + 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.
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index e0c42ea9b8d0..113fd42ec36d 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -183,6 +183,10 @@ 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_lookup_extent_before(struct xfs_inode *ip,
> + struct xfs_ifork *ifp, xfs_fileoff_t *end,
> + 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);
> void xfs_iext_update_extent(struct xfs_inode *ip, int state,
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 37e603bf1591..1205747e1409 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -733,18 +733,13 @@ xfs_reflink_end_cow(
> xfs_ilock(ip, XFS_ILOCK_EXCL);
> xfs_trans_ijoin(tp, ip, 0);
>
> - /* If there is a hole at end_fsb - 1 go to the previous extent */
> - if (!xfs_iext_lookup_extent(ip, ifp, end_fsb - 1, &idx, &got) ||
> - got.br_startoff > end_fsb) {
> - /*
> - * In case of racing, overlapping AIO writes no COW extents
> - * might be left by the time I/O completes for the loser of
> - * the race. In that case we are done.
> - */
> - if (idx <= 0)
> - goto out_cancel;
> - xfs_iext_get_extent(ifp, --idx, &got);
> - }
> + /*
> + * In case of racing, overlapping AIO writes no COW extents might be
> + * left by the time I/O completes for the loser of the race. In that
> + * case we are done.
> + */
> + if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &idx, &got))
> + goto out_cancel;
>
> /* Walk backwards until we're out of the I/O range... */
> while (got.br_startoff + got.br_blockcount > offset_fsb) {
> --
> 2.14.2
>
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