Re: [PATCH v3 2/3] btrfs: replace stripe extents

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

在 2024/7/12 17:18, Johannes Thumshirn 写道:
> From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
>
> Update stripe extents in case a write to an already existing address
> incoming.
>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Reviewed-by: Qu Wenruo <wqu@suse.com>

> ---
>   fs/btrfs/raid-stripe-tree.c | 33 +++++++++++++++++++++++++++++++++
>   1 file changed, 33 insertions(+)
>
> diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
> index e6f7a234b8f6..53ca2c1a32ac 100644
> --- a/fs/btrfs/raid-stripe-tree.c
> +++ b/fs/btrfs/raid-stripe-tree.c
> @@ -73,6 +73,36 @@ int btrfs_delete_raid_extent(struct btrfs_trans_handle *trans, u64 start, u64 le
>   	return ret;
>   }
>
> +static int update_raid_extent_item(struct btrfs_trans_handle *trans,
> +				   struct btrfs_key *key,
> +				   struct btrfs_stripe_extent *stripe_extent,
> +				   const size_t item_size)
> +{
> +	struct btrfs_path *path;
> +	struct extent_buffer *leaf;
> +	int ret;
> +	int slot;
> +
> +	path = btrfs_alloc_path();
> +	if (!path)
> +		return -ENOMEM;
> +
> +	ret = btrfs_search_slot(trans, trans->fs_info->stripe_root, key, path,
> +				0, 1);
> +	if (ret)
> +		return ret == 1 ? ret : -EINVAL;
> +
> +	leaf = path->nodes[0];
> +	slot = path->slots[0];
> +
> +	write_extent_buffer(leaf, stripe_extent,
> +			    btrfs_item_ptr_offset(leaf, slot), item_size);

Since the replace one should be the same size, an ASSERT() would make it
easier to catch future problems.

Thanks,
Qu
> +	btrfs_mark_buffer_dirty(trans, leaf);
> +	btrfs_free_path(path);
> +
> +	return ret;
> +}
> +
>   static int btrfs_insert_one_raid_extent(struct btrfs_trans_handle *trans,
>   					struct btrfs_io_context *bioc)
>   {
> @@ -112,6 +142,9 @@ static int btrfs_insert_one_raid_extent(struct btrfs_trans_handle *trans,
>
>   	ret = btrfs_insert_item(trans, stripe_root, &stripe_key, stripe_extent,
>   				item_size);
> +	if (ret == -EEXIST)
> +		ret = update_raid_extent_item(trans, &stripe_key, stripe_extent,
> +					      item_size);
>   	if (ret)
>   		btrfs_abort_transaction(trans, ret);
>
>