btrfs_qgroup_inherit structure has two members, num_ref_copies and num_excl_copies, to info btrfs kernel modules to inherit (copy) rfer/excl numbers at snapshot/subvolume creation time.
Since qgroup number is already hard to maintain for multi-level qgroup scenario, allowing user to manually manipulate qgroup inherit is quite easy to screw up qgroup numbers. Although btrfs-progs supports such inheritance specification, the options are hidden from user and not documented. So there is no need to allow user to manually specify inheritance in kernel. Reported-by: Omar Sandoval <[email protected]> Reported-by: Nikolay Borisov <[email protected]> Signed-off-by: Qu Wenruo <[email protected]> --- changelog: v2: Don't return -ENOTTY, but just ignoring value set in num_ref/excl_copies, suggested by Nikolay. Don't modify the UAPI members, but add comment to deprecate them, suggested by Omar. And add Omar as first reporter. --- fs/btrfs/qgroup.c | 54 +++++++++++++--------------------------------- include/uapi/linux/btrfs.h | 4 ++-- 2 files changed, 17 insertions(+), 41 deletions(-) diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 168fd03ca3ac..42c6b35d8d7f 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -2158,9 +2158,22 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, } if (inherit) { + /* + * num_excl/rfer_copies indicate how many qgroup pairs needs + * to be manually inherited (copy rfer or excl from src + * qgroup to dst, along with qgroup relationship added) + * + * Allowing user to manipulate inheritance can easily cause + * problem in multi-level qgroup scenario. + * And the ioctl interface is hidden in btrfs-progs for a long + * time, deprecate them should not be a big problem. + * + * Here we just ignore any value set in num_excl/rfer_copies, + * and only handles qgroup relationship specified by + * @num_qgroups. + */ i_qgroups = (u64 *)(inherit + 1); - nums = inherit->num_qgroups + 2 * inherit->num_ref_copies + - 2 * inherit->num_excl_copies; + nums = inherit->num_qgroups; for (i = 0; i < nums; ++i) { srcgroup = find_qgroup_rb(fs_info, *i_qgroups); @@ -2286,43 +2299,6 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, ++i_qgroups; } - for (i = 0; i < inherit->num_ref_copies; ++i, i_qgroups += 2) { - struct btrfs_qgroup *src; - struct btrfs_qgroup *dst; - - if (!i_qgroups[0] || !i_qgroups[1]) - continue; - - src = find_qgroup_rb(fs_info, i_qgroups[0]); - dst = find_qgroup_rb(fs_info, i_qgroups[1]); - - if (!src || !dst) { - ret = -EINVAL; - goto unlock; - } - - dst->rfer = src->rfer - level_size; - dst->rfer_cmpr = src->rfer_cmpr - level_size; - } - for (i = 0; i < inherit->num_excl_copies; ++i, i_qgroups += 2) { - struct btrfs_qgroup *src; - struct btrfs_qgroup *dst; - - if (!i_qgroups[0] || !i_qgroups[1]) - continue; - - src = find_qgroup_rb(fs_info, i_qgroups[0]); - dst = find_qgroup_rb(fs_info, i_qgroups[1]); - - if (!src || !dst) { - ret = -EINVAL; - goto unlock; - } - - dst->excl = src->excl + level_size; - dst->excl_cmpr = src->excl_cmpr + level_size; - } - unlock: spin_unlock(&fs_info->qgroup_lock); out: diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h index ce615b75e855..a10342d491bc 100644 --- a/include/uapi/linux/btrfs.h +++ b/include/uapi/linux/btrfs.h @@ -80,8 +80,8 @@ struct btrfs_qgroup_limit { struct btrfs_qgroup_inherit { __u64 flags; __u64 num_qgroups; - __u64 num_ref_copies; - __u64 num_excl_copies; + __u64 num_ref_copies; /* DEPRECATED, will just be ignored */ + __u64 num_excl_copies; /* DEPRECATED, will just be ignored */ struct btrfs_qgroup_limit lim; __u64 qgroups[0]; }; -- 2.15.1 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
