Re: [PATCH 1/2] btrfs: qgroup: fix wrong qgroup metadata reserve for delayed inode

Josef Bacik
2020-08-24T18:02:12Z

On 7/24/20 2:46 AM, Qu Wenruo wrote:
> For delayed inode facility, qgroup metadata is reserved for it, and
> later freed.
>
> However we're freeing more bytes than we reserved.
> In btrfs_delayed_inode_reserve_metadata():
>
> num_bytes = btrfs_calc_metadata_size(fs_info, 1);
> ...
> ret = btrfs_qgroup_reserve_meta_prealloc(root,
> fs_info->nodesize, true);
> ...
> if (!ret) {
> node->bytes_reserved = num_bytes;
>
> But in btrfs_delayed_inode_release_metadata():
>
> if (qgroup_free)
> btrfs_qgroup_free_meta_prealloc(node->root,
> node->bytes_reserved);
> else
> btrfs_qgroup_convert_reserved_meta(node->root,
> node->bytes_reserved);
>
> This means, we're always releasing more qgroup metadata rsv than we have
> reserved.
>
> This won't trigger selftest warning, as btrfs qgroup metadata rsv has
> extra protection against cases like quota enabled half-way.
>
> But we still need to fix this problem any way.
>
> This patch will use the same num_bytes for qgroup metadata rsv so we
> could handle it correctly.
>
> Fixes: f218ea6c4792 ("btrfs: delayed-inode: Remove wrong qgroup meta reservation calls")
> Signed-off-by: Qu Wenruo <wqu@suse.com>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef