On Wed, May 23, 2018 at 04:43:48PM +0200, Christoph Hellwig wrote:
> In the only caller we just did a lookup in the COW extent tree for
> the same offset. Reuse that result and save a lookup, as well as
> shortening the ilock hold time.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/xfs/xfs_aops.c | 25 +++++++++++++++++--------
> fs/xfs/xfs_reflink.c | 33 ---------------------------------
> fs/xfs/xfs_reflink.h | 2 --
> 3 files changed, 17 insertions(+), 43 deletions(-)
>
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index a4b4a7037deb..354d26d66c12 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -383,11 +383,12 @@ xfs_map_blocks(
> struct xfs_inode *ip = XFS_I(inode);
> struct xfs_mount *mp = ip->i_mount;
> ssize_t count = i_blocksize(inode);
> - xfs_fileoff_t offset_fsb, end_fsb;
> + xfs_fileoff_t offset_fsb, end_fsb, cow_fsb = 0;
cow_fsb should probably be initialized to NULLFSBLOCK rather than 0.
With that, you also shouldn't need cow_valid. Otherwise looks Ok to me.
Brian
> int whichfork = XFS_DATA_FORK;
> struct xfs_iext_cursor icur;
> int error = 0;
> int nimaps = 1;
> + bool cow_valid = false;
>
> if (XFS_FORCED_SHUTDOWN(mp))
> return -EIO;
> @@ -407,8 +408,11 @@ xfs_map_blocks(
> * it directly instead of looking up anything in the data fork.
> */
> if (xfs_is_reflink_inode(ip) &&
> - xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, imap) &&
> - imap->br_startoff <= offset_fsb) {
> + xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, imap)) {
> + cow_fsb = imap->br_startoff;
> + cow_valid = true;
> + }
> + if (cow_valid && cow_fsb <= offset_fsb) {
> xfs_iunlock(ip, XFS_ILOCK_SHARED);
> /*
> * Truncate can race with writeback since writeback doesn't
> @@ -430,6 +434,10 @@ xfs_map_blocks(
>
> error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
> imap, &nimaps, XFS_BMAPI_ENTIRE);
> + xfs_iunlock(ip, XFS_ILOCK_SHARED);
> + if (error)
> + return error;
> +
> if (!nimaps) {
> /*
> * Lookup returns no match? Beyond eof? regardless,
> @@ -451,16 +459,17 @@ xfs_map_blocks(
> * is a pending CoW reservation before the end of this extent,
> * so that we pick up the COW extents in the next iteration.
> */
> - xfs_reflink_trim_irec_to_next_cow(ip, offset_fsb, imap);
> + if (cow_valid &&
> + cow_fsb < imap->br_startoff + imap->br_blockcount) {
> + imap->br_blockcount = cow_fsb - imap->br_startoff;
> + trace_xfs_reflink_trim_irec(ip, imap);
> + }
> +
> if (imap->br_state == XFS_EXT_UNWRITTEN)
> *type = XFS_IO_UNWRITTEN;
> else
> *type = XFS_IO_OVERWRITE;
> }
> - xfs_iunlock(ip, XFS_ILOCK_SHARED);
> - if (error)
> - return error;
> -
> done:
> switch (*type) {
> case XFS_IO_HOLE:
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 8e5eb8e70c89..ff76bc56ff3d 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -484,39 +484,6 @@ xfs_reflink_allocate_cow(
> return error;
> }
>
> -/*
> - * Trim an extent to end at the next CoW reservation past offset_fsb.
> - */
> -void
> -xfs_reflink_trim_irec_to_next_cow(
> - struct xfs_inode *ip,
> - xfs_fileoff_t offset_fsb,
> - struct xfs_bmbt_irec *imap)
> -{
> - struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
> - struct xfs_bmbt_irec got;
> - struct xfs_iext_cursor icur;
> -
> - if (!xfs_is_reflink_inode(ip))
> - return;
> -
> - /* Find the extent in the CoW fork. */
> - if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
> - return;
> -
> - /* This is the extent before; try sliding up one. */
> - if (got.br_startoff < offset_fsb) {
> - if (!xfs_iext_next_extent(ifp, &icur, &got))
> - return;
> - }
> -
> - if (got.br_startoff >= imap->br_startoff + imap->br_blockcount)
> - return;
> -
> - imap->br_blockcount = got.br_startoff - imap->br_startoff;
> - trace_xfs_reflink_trim_irec(ip, imap);
> -}
> -
> /*
> * Cancel CoW reservations for some block range of an inode.
> *
> diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
> index 15a456492667..e8d4d50c629f 100644
> --- a/fs/xfs/xfs_reflink.h
> +++ b/fs/xfs/xfs_reflink.h
> @@ -32,8 +32,6 @@ extern int xfs_reflink_allocate_cow(struct xfs_inode *ip,
> struct xfs_bmbt_irec *imap, bool *shared, uint *lockmode);
> extern int xfs_reflink_convert_cow(struct xfs_inode *ip, xfs_off_t offset,
> xfs_off_t count);
> -extern void xfs_reflink_trim_irec_to_next_cow(struct xfs_inode *ip,
> - xfs_fileoff_t offset_fsb, struct xfs_bmbt_irec *imap);
>
> extern int xfs_reflink_cancel_cow_blocks(struct xfs_inode *ip,
> struct xfs_trans **tpp, xfs_fileoff_t offset_fsb,
> --
> 2.17.0
>
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