On Thu, Jan 14, 2016 at 5:57 AM, Qu Wenruo <quwenruo@xxxxxxxxxxxxxx> wrote:
> Now on-disk backend can delete hash now.
>
> Signed-off-by: Wang Xiaoguang <wangxg.fnst@xxxxxxxxxxxxxx>
> Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/dedup.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 93 insertions(+)
>
> diff --git a/fs/btrfs/dedup.c b/fs/btrfs/dedup.c
> index 4acbbfb..66c8f05 100644
> --- a/fs/btrfs/dedup.c
> +++ b/fs/btrfs/dedup.c
> @@ -437,6 +437,97 @@ static int inmem_del(struct btrfs_dedup_info *dedup_info, u64 bytenr)
> return 0;
> }
>
> +/*
> + * If prepare_del is given, this will setup search_slot() for delete.
> + * Caller needs to do proper locking.
> + *
> + * Return > 0 for found.
> + * Return 0 for not found.
> + * Return < 0 for error.
> + */
> +static int ondisk_search_bytenr(struct btrfs_trans_handle *trans,
> + struct btrfs_dedup_info *dedup_info,
> + struct btrfs_path *path, u64 bytenr,
> + int prepare_del)
> +{
> + struct btrfs_key key;
> + struct btrfs_root *dedup_root = dedup_info->dedup_root;
> + int ret;
> + int ins_len = 0;
> + int cow = 0;
> +
> + if (prepare_del) {
> + if (WARN_ON(trans == NULL))
> + return -EINVAL;
> + cow = 1;
> + ins_len = -1;
> + }
> +
> + key.objectid = bytenr;
> + key.type = BTRFS_DEDUP_BYTENR_ITEM_KEY;
> + key.offset = (u64)-1;
> +
> + ret = btrfs_search_slot(trans, dedup_root, &key, path,
> + ins_len, cow);
> + if (ret < 0)
> + return ret;
> +
> + WARN_ON(ret == 0);
If ret == 0 (who knows if one day there won't be an hash algorithm
that produces 64 bits hashes with all bits set for some inputs), then
we shouldn't do the btrfs_previous_item() call, which would make us
miss the item.
> + ret = btrfs_previous_item(dedup_root, path, bytenr,
> + BTRFS_DEDUP_BYTENR_ITEM_KEY);
> + if (ret < 0)
> + return ret;
> + if (ret > 0)
> + return 0;
> + return 1;
> +}
> +
> +static int ondisk_del(struct btrfs_trans_handle *trans,
> + struct btrfs_dedup_info *dedup_info, u64 bytenr)
> +{
> + struct btrfs_root *dedup_root = dedup_info->dedup_root;
> + struct btrfs_path *path;
> + struct btrfs_key key;
> + int ret;
> +
> + path = btrfs_alloc_path();
> + if (!path)
> + return -ENOMEM;
> +
> + key.objectid = bytenr;
> + key.type = BTRFS_DEDUP_BYTENR_ITEM_KEY;
> + key.offset = 0;
> +
> + mutex_lock(&dedup_info->lock);
> +
> + ret = ondisk_search_bytenr(trans, dedup_info, path, bytenr, 1);
> + if (ret <= 0)
> + goto out;
> +
> + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
> + btrfs_del_item(trans, dedup_root, path);
> + btrfs_release_path(path);
> +
> + /* Search for hash item and delete it */
> + key.objectid = key.offset;
> + key.type = BTRFS_DEDUP_HASH_ITEM_KEY;
> + key.offset = bytenr;
> +
> + ret = btrfs_search_slot(trans, dedup_root, &key, path, -1, 1);
> + if (WARN_ON(ret > 0)) {
> + ret = -ENOENT;
> + goto out;
> + }
> + if (ret < 0)
> + goto out;
> + btrfs_del_item(trans, dedup_root, path);
btrfs_del_item() can return errors.
> +
> +out:
> + btrfs_free_path(path);
> + mutex_unlock(&dedup_info->lock);
> + return ret;
> +}
> +
> /* Remove a dedup hash from dedup tree */
> int btrfs_dedup_del(struct btrfs_trans_handle *trans, struct btrfs_root *root,
> u64 bytenr)
> @@ -449,6 +540,8 @@ int btrfs_dedup_del(struct btrfs_trans_handle *trans, struct btrfs_root *root,
>
> if (dedup_info->backend == BTRFS_DEDUP_BACKEND_INMEMORY)
> return inmem_del(dedup_info, bytenr);
> + if (dedup_info->backend == BTRFS_DEDUP_BACKEND_ONDISK)
> + return ondisk_del(trans, dedup_info, bytenr);
> return -EINVAL;
> }
>
> --
> 2.7.0
>
>
>
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"Reasonable men adapt themselves to the world.
Unreasonable men adapt the world to themselves.
That's why all progress depends on unreasonable men."
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