On Tue, Oct 31, 2017 at 04:22:26PM +0200, Christoph Hellwig wrote:
> Instead of looking up extents to convert and calling xfs_bmapi_write on
> each of them just let xfs_bmapi_write handle the full range. To make
> this robust add a new XFS_BMAPI_CONVERT_ONLY that only converts ranges
> and never allocates blocks.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/xfs/libxfs/xfs_bmap.c | 3 ++-
> fs/xfs/libxfs/xfs_bmap.h | 3 +++
> fs/xfs/xfs_reflink.c | 29 +++++++++++------------------
> 3 files changed, 16 insertions(+), 19 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 453dc1ae76ab..e020bd3f8717 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -4330,7 +4330,8 @@ xfs_bmapi_write(
> * First, deal with the hole before the allocated space
> * that we found, if any.
> */
> - if (need_alloc || wasdelay) {
> + if ((need_alloc || wasdelay) &&
> + !(flags & XFS_BMAPI_CONVERT_ONLY)) {
> bma.eof = eof;
> bma.conv = !!(flags & XFS_BMAPI_CONVERT);
> bma.wasdel = wasdelay;
> diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
> index 195f335f4615..fba60ed7aea5 100644
> --- a/fs/xfs/libxfs/xfs_bmap.h
> +++ b/fs/xfs/libxfs/xfs_bmap.h
> @@ -113,6 +113,9 @@ struct xfs_extent_free_item
> /* Only convert delalloc space, don't allocate entirely new extents */
> #define XFS_BMAPI_DELALLOC 0x400
>
> +/* Only convert unwritten extents, don't allocate new hotels */
New ... blocks?
> +#define XFS_BMAPI_CONVERT_ONLY 0x800
I wonder if this and XFS_BMAPI_DELALLOC could be solved with a single
flag that means "don't fill in any holes; only touch pre-existing
extents" ?
(Though I guess Dave is still working on getting /rid/ of BMAPI_DELALLOC
so maybe that doesn't matter...)
> #define XFS_BMAPI_FLAGS \
> { XFS_BMAPI_ENTIRE, "ENTIRE" }, \
> { XFS_BMAPI_METADATA, "METADATA" }, \
If you do end up adding a new BMAPI flag, this needs updating so the
tracepoints keep working.
--D
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 43bec0def51d..99c5d4dbc5d3 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -353,29 +353,22 @@ xfs_reflink_convert_cow(
> xfs_off_t offset,
> xfs_off_t count)
> {
> - struct xfs_bmbt_irec got;
> - struct xfs_defer_ops dfops;
> struct xfs_mount *mp = ip->i_mount;
> - struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
> xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
> xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
> - struct xfs_iext_cursor ext;
> - bool found;
> - int error = 0;
> -
> - xfs_ilock(ip, XFS_ILOCK_EXCL);
> + xfs_filblks_t count_fsb = end_fsb - offset_fsb;
> + struct xfs_bmbt_irec imap;
> + struct xfs_defer_ops dfops;
> + xfs_fsblock_t first_block = NULLFSBLOCK;
> + int nimaps = 1, error = 0;
>
> - /* Convert all the extents to real from unwritten. */
> - for (found = xfs_iext_lookup_extent(ip, ifp, offset_fsb, &ext, &got);
> - found && got.br_startoff < end_fsb;
> - found = xfs_iext_next_extent(ifp, &ext, &got)) {
> - error = xfs_reflink_convert_cow_extent(ip, &got, offset_fsb,
> - end_fsb - offset_fsb, &dfops);
> - if (error)
> - break;
> - }
> + ASSERT(count != 0);
>
> - /* Finish up. */
> + xfs_ilock(ip, XFS_ILOCK_EXCL);
> + error = xfs_bmapi_write(NULL, ip, offset_fsb, count_fsb,
> + XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT |
> + XFS_BMAPI_CONVERT_ONLY, &first_block, 0, &imap, &nimaps,
> + &dfops);
> xfs_iunlock(ip, XFS_ILOCK_EXCL);
> return error;
> }
> --
> 2.14.2
>
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