On Tue, Oct 02, 2018 at 10:42:03AM -0700, Christoph Hellwig wrote:
> We only need to allocate blocks for zeroing for reflink inodes,
> and for we currently have a special case for reflink files in
> the otherwise direct I/O path that I'd like to get rid of.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> fs/xfs/xfs_iomap.c | 44 ++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 38 insertions(+), 6 deletions(-)
>
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 6320aca39f39..9b572a1fbd42 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -62,6 +62,21 @@ xfs_bmbt_to_iomap(
> iomap->dax_dev = xfs_find_daxdev_for_inode(VFS_I(ip));
> }
>
> +static void
> +xfs_hole_to_iomap(
> + struct xfs_inode *ip,
> + struct iomap *iomap,
> + xfs_fileoff_t offset_fsb,
> + xfs_fileoff_t end_fsb)
> +{
> + iomap->addr = IOMAP_NULL_ADDR;
> + iomap->type = IOMAP_HOLE;
> + iomap->offset = XFS_FSB_TO_B(ip->i_mount, offset_fsb);
> + iomap->length = XFS_FSB_TO_B(ip->i_mount, end_fsb - offset_fsb);
> + iomap->bdev = xfs_find_bdev_for_inode(VFS_I(ip));
> + iomap->dax_dev = xfs_find_daxdev_for_inode(VFS_I(ip));
> +}
> +
> xfs_extlen_t
> xfs_eof_alignment(
> struct xfs_inode *ip,
> @@ -502,6 +517,7 @@ xfs_file_iomap_begin_delay(
> struct inode *inode,
> loff_t offset,
> loff_t count,
> + unsigned flags,
> struct iomap *iomap)
> {
> struct xfs_inode *ip = XFS_I(inode);
> @@ -538,13 +554,23 @@ xfs_file_iomap_begin_delay(
> goto out_unlock;
> }
>
> + end_fsb = min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
> +
> eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got);
> - if (!eof && got.br_startoff <= offset_fsb) {
> - if (xfs_is_reflink_inode(ip)) {
> + if (eof)
> + got.br_startoff = end_fsb; /* fake hole until the end */
> +
> + if (got.br_startoff <= offset_fsb) {
> + /*
> + * For reflink files we may need a delalloc reservation when
> + * overwriting shared extents. This includes zeroing of
> + * existing extents that contain data.
> + */
> + if (xfs_is_reflink_inode(ip) &&
> + ((flags & IOMAP_WRITE) ||
> + got.br_state != XFS_EXT_UNWRITTEN)) {
> bool shared;
>
> - end_fsb = min(XFS_B_TO_FSB(mp, offset + count),
> - maxbytes_fsb);
> xfs_trim_extent(&got, offset_fsb, end_fsb - offset_fsb);
> error = xfs_reflink_reserve_cow(ip, &got, &shared);
> if (error)
> @@ -555,6 +581,11 @@ xfs_file_iomap_begin_delay(
> goto done;
> }
>
> + if (flags & IOMAP_ZERO) {
> + xfs_hole_to_iomap(ip, iomap, offset_fsb, got.br_startoff);
> + goto out_unlock;
> + }
> +
> error = xfs_qm_dqattach_locked(ip, false);
> if (error)
> goto out_unlock;
> @@ -1009,10 +1040,11 @@ xfs_file_iomap_begin(
> if (XFS_FORCED_SHUTDOWN(mp))
> return -EIO;
>
> - if (((flags & (IOMAP_WRITE | IOMAP_DIRECT)) == IOMAP_WRITE) &&
> + if ((flags & (IOMAP_WRITE | IOMAP_ZERO)) && !(flags & IOMAP_DIRECT) &&
> !IS_DAX(inode) && !xfs_get_extsz_hint(ip)) {
> /* Reserve delalloc blocks for regular writeback. */
> - return xfs_file_iomap_begin_delay(inode, offset, length, iomap);
> + return xfs_file_iomap_begin_delay(inode, offset, length, flags,
> + iomap);
> }
>
> /*
> --
> 2.19.0
>
