Hi Josef,
please consider this patch for btrfs-next and for the following merge window
(3.13). The fact that there's another problem concerning qgroups as discussed in
the rest of this thread doesn't make this patch any less correct.
Thanks,
-Jan
On Thu, October 24, 2013 at 15:22 (+0200), Jan Schmidt wrote:
> btrfs_dec_ref() queued a delayed ref for owner of a tree block. The qgroup
> tracking is based on delayed refs. The owner of a tree block is set when a
> tree block is allocated, it is never updated.
>
> When you allocate a tree block and then remove the subvolume that did the
> allocation, the qgroup accounting for that removal is correct. However, the
> removal was accounted again for each subvolume deletion that also referenced
> the tree block, because accounting was erroneously based on the owner.
>
> Instead of queueing delayed refs for the non-existent owner, we now
> queue delayed refs for the root being removed. This fixes the qgroup
> accounting.
>
> Signed-off-by: Jan Schmidt <list.btrfs@xxxxxxxxxxxxx>
> Tested-by: <dustymabe@xxxxxxxxx>
> ---
> fs/btrfs/extent-tree.c | 14 +++++++++-----
> 1 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index d58bef1..7846cae 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -3004,12 +3004,11 @@ out:
> static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
> struct btrfs_root *root,
> struct extent_buffer *buf,
> - int full_backref, int inc, int for_cow)
> + int full_backref, u64 ref_root, int inc, int for_cow)
> {
> u64 bytenr;
> u64 num_bytes;
> u64 parent;
> - u64 ref_root;
> u32 nritems;
> struct btrfs_key key;
> struct btrfs_file_extent_item *fi;
> @@ -3019,7 +3018,6 @@ static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
> int (*process_func)(struct btrfs_trans_handle *, struct btrfs_root *,
> u64, u64, u64, u64, u64, u64, int);
>
> - ref_root = btrfs_header_owner(buf);
> nritems = btrfs_header_nritems(buf);
> level = btrfs_header_level(buf);
>
> @@ -3075,13 +3073,19 @@ fail:
> int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
> struct extent_buffer *buf, int full_backref, int for_cow)
> {
> - return __btrfs_mod_ref(trans, root, buf, full_backref, 1, for_cow);
> + u64 ref_root;
> +
> + ref_root = btrfs_header_owner(buf);
> +
> + return __btrfs_mod_ref(trans, root, buf, full_backref, ref_root,
> + 1, for_cow);
> }
>
> int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
> struct extent_buffer *buf, int full_backref, int for_cow)
> {
> - return __btrfs_mod_ref(trans, root, buf, full_backref, 0, for_cow);
> + return __btrfs_mod_ref(trans, root, buf, full_backref, root->objectid,
> + 0, for_cow);
> }
>
> static int write_one_cache_group(struct btrfs_trans_handle *trans,
>
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