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: Nikolay Borisov <nborisov@xxxxxxxx>
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
The only concern is, currently we don't have good tool to handle
inheritance of multi-level qgroups.
The only method to get qgroup numbers correct is to run a quota rescan.
So there may be some case where experienced (well, mostly a developer)
user can use the hidden btrfs-progs options or manually craft an ioctl
to handle multi-level qgroups without costly rescan.
---
fs/btrfs/qgroup.c | 56 ++++++++++++++--------------------------------
include/uapi/linux/btrfs.h | 4 ++--
2 files changed, 19 insertions(+), 41 deletions(-)
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 168fd03ca3ac..d8a2413272f9 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2158,9 +2158,24 @@ 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)
+ *
+ * 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.
+ */
+ if (inherit->__num_excl_copies || inherit->__num_ref_copies) {
+ ret = -ENOTTY;
+ btrfs_warn(fs_info,
+ "manually inherit excl/rfer is no longer supported");
+ goto out;
+ }
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 +2301,6 @@ 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..099e088414d6 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 */
+ __u64 __num_excl_copies; /* DEPRECATED */
struct btrfs_qgroup_limit lim;
__u64 qgroups[0];
};
--
2.15.1
--
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