btrfs: extend balance filter usage to take minimum and maximum

Similar to the 'limit' filter, we can enhance the 'usage' filter to
accept a range. The change is backward compatible, the range is applied
only in connection with the BTRFS_BALANCE_ARGS_USAGE_RANGE flag.

We don't have a usecase yet, the current syntax has been sufficient. The
enhancement should provide parity with other range-like filters.

Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 17a94704b183..dea893199257 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -206,7 +206,13 @@ struct btrfs_ioctl_feature_flags {
  */
 struct btrfs_balance_args {
         __u64 profiles;
-        __u64 usage;
+        union {
+                __le64 usage;
+                struct {
+                        __le32 usage_min;
+                        __le32 usage_max;
+                };
+        };
         __u64 devid;
         __u64 pstart;
         __u64 pend;