On Thu, Jan 25, 2018 at 06:05:00PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Since the CoW fork only exists in memory, it is incorrect to update the
> on-disk quota block counts when we modify the CoW fork. Unlike the data
> fork, even real extents in the CoW fork are only reservations (on-disk
> they're owned by the refcountbt) so they must not be tracked in the on
> disk quota info.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
Looks sane.. just a couple comments from my braindump on the previous
patch and a few comment suggestions that help me understand this better
(feel free to tweak, rewrite, etc.).
> fs/xfs/libxfs/xfs_bmap.c | 33 ++++++++++++++++++++++++++++++---
> fs/xfs/libxfs/xfs_bmap.h | 2 +-
> fs/xfs/xfs_reflink.c | 12 ++++++------
> 3 files changed, 37 insertions(+), 10 deletions(-)
>
>
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 6ad79ea..a59d5be 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -3343,8 +3343,26 @@ xfs_bmap_btalloc_accounting(
> struct xfs_bmalloca *ap,
> struct xfs_alloc_arg *args)
> {
> - if (!(ap->flags & XFS_BMAPI_COWFORK))
> - ap->ip->i_d.di_nblocks += args->len;
> + if (ap->flags & XFS_BMAPI_COWFORK) {
/*
* COW fork blocks are in-core only and thus are treated as in-core
* quota reservation (like delalloc blocks) even when converted to real
* blocks. The quota reservation is not accounted to disk until blocks
* are remapped to the data fork. So if these blocks were previously
* delalloc, we already have quota reservation and there's nothing to do
* yet.
*/
> + /* Filling a previously reserved extent; nothing to do here. */
> + if (ap->wasdel)
> + return;
> +
> + /*
> + * If we get here, we're filling a CoW hole with a real
> + * (non-delalloc) CoW extent having reserved enough blocks
> + * from both q_res_bcount and qt_blk_res to guarantee that we
> + * won't run out of space. The unused qt_blk_res is given
> + * back to q_res_bcount when the transaction commits, so we
> + * must decrease qt_blk_res without decreasing q_res_bcount.
> + */
/*
* Otherwise, we've allocated blocks in a hole. The transaction has
* acquired in-core quota reservation for this extent. Rather than
* account these as real blocks, however, we reduce the transaction
* quota reservation based on the allocation. This essentially transfers
* the transaction quota reservation to that of a delalloc extent.
*/
> + xfs_trans_mod_dquot_byino(ap->tp, ap->ip, XFS_TRANS_DQ_RES_BLKS,
> + -(long)args->len);
> + return;
> + }
> +
> + /* data/attr fork only */
> + ap->ip->i_d.di_nblocks += args->len;
> xfs_trans_log_inode(ap->tp, ap->ip, XFS_ILOG_CORE);
> if (ap->wasdel)
> ap->ip->i_delayed_blks -= args->len;
> @@ -4761,13 +4779,15 @@ xfs_bmap_del_extent_cow(
> struct xfs_inode *ip,
> struct xfs_iext_cursor *icur,
> struct xfs_bmbt_irec *got,
> - struct xfs_bmbt_irec *del)
> + struct xfs_bmbt_irec *del,
> + bool free_quotares)
> {
> struct xfs_mount *mp = ip->i_mount;
> struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
> struct xfs_bmbt_irec new;
> xfs_fileoff_t del_endoff, got_endoff;
> int state = BMAP_COWFORK;
> + int error;
>
> XFS_STATS_INC(mp, xs_del_exlist);
>
> @@ -4824,6 +4844,13 @@ xfs_bmap_del_extent_cow(
> xfs_iext_insert(ip, icur, &new, state);
> break;
> }
> +
> + /* Remove the quota reservation */
> + if (!free_quotares)
> + return;
> + error = xfs_trans_reserve_quota_nblks(NULL, ip,
> + -(long)del->br_blockcount, 0, XFS_QMOPT_RES_REGBLKS);
> + ASSERT(error == 0);
Might as well pull this into the only free_quotares = true caller.
Brian
> }
>
> /*
> diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
> index e36d757..e99f28f 100644
> --- a/fs/xfs/libxfs/xfs_bmap.h
> +++ b/fs/xfs/libxfs/xfs_bmap.h
> @@ -224,7 +224,7 @@ int xfs_bmap_del_extent_delay(struct xfs_inode *ip, int whichfork,
> struct xfs_bmbt_irec *del);
> void xfs_bmap_del_extent_cow(struct xfs_inode *ip,
> struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *got,
> - struct xfs_bmbt_irec *del);
> + struct xfs_bmbt_irec *del, bool free_quotares);
> uint xfs_default_attroffset(struct xfs_inode *ip);
> int xfs_bmap_collapse_extents(struct xfs_trans *tp, struct xfs_inode *ip,
> xfs_fileoff_t *next_fsb, xfs_fileoff_t offset_shift_fsb,
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 82abff6..3644a08 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -599,10 +599,6 @@ xfs_reflink_cancel_cow_blocks(
> del.br_startblock, del.br_blockcount,
> NULL);
>
> - /* Update quota accounting */
> - xfs_trans_mod_dquot_byino(*tpp, ip, XFS_TRANS_DQ_BCOUNT,
> - -(long)del.br_blockcount);
> -
> /* Roll the transaction */
> xfs_defer_ijoin(&dfops, ip);
> error = xfs_defer_finish(tpp, &dfops);
> @@ -612,7 +608,7 @@ xfs_reflink_cancel_cow_blocks(
> }
>
> /* Remove the mapping from the CoW fork. */
> - xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
> + xfs_bmap_del_extent_cow(ip, &icur, &got, &del, true);
> } else {
> /* Didn't do anything, push cursor back. */
> xfs_iext_prev(ifp, &icur);
> @@ -795,8 +791,12 @@ xfs_reflink_end_cow(
> if (error)
> goto out_defer;
>
> + /* Charge this new data fork mapping to the on-disk quota. */
> + xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_DELBCOUNT,
> + (long)del.br_blockcount);
> +
> /* Remove the mapping from the CoW fork. */
> - xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
> + xfs_bmap_del_extent_cow(ip, &icur, &got, &del, false);
>
> xfs_defer_ijoin(&dfops, ip);
> error = xfs_defer_finish(&tp, &dfops);
>
> --
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