Re: [PATCH] btrfs: qgroup: add missing extent changeset release

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

在 2024/8/28 00:42, Fedor Pchelkin 写道:
> The extent changeset may have some additional memory dynamically allocated
> for ulist in result of clear_record_extent_bits() execution.
>
> Release it after the local changeset is no longer needed in
> BTRFS_QGROUP_MODE_DISABLED case.
>
> Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
>
> Reported-by: syzbot+81670362c283f3dd889c@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/lkml/000000000000aa8c0c060ade165e@google.com
> Fixes: af0e2aab3b70 ("btrfs: qgroup: flush reservations during quota disable")
> Cc: stable@vger.kernel.org # 6.10+
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>

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

In this particular case, the changeset is really only locally utilized,
thus should always be released.

Thanks,
Qu
> ---
>   fs/btrfs/qgroup.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index 5d57a285d59b..4f1fa5d427e1 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -4345,9 +4345,10 @@ static int __btrfs_qgroup_release_data(struct btrfs_inode *inode,
>
>   	if (btrfs_qgroup_mode(inode->root->fs_info) == BTRFS_QGROUP_MODE_DISABLED) {
>   		extent_changeset_init(&changeset);
> -		return clear_record_extent_bits(&inode->io_tree, start,
> -						start + len - 1,
> -						EXTENT_QGROUP_RESERVED, &changeset);
> +		ret = clear_record_extent_bits(&inode->io_tree, start,
> +					       start + len - 1,
> +					       EXTENT_QGROUP_RESERVED, &changeset);
> +		goto out;
>   	}
>
>   	/* In release case, we shouldn't have @reserved */