btrfs-progs: extend balance args to take min/max usage filter

Add the overlapping usage and [usage_min, usage_max] members to the
balance args. The min/max values are interpreted iff the corresponding
flag BTRFS_BALANCE_ARGS_USAGE_RANGE is set.

The minimum boundary is inclusive, maximum is exclusive:
* usage_min <= chunk_usage < usage_max

Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/ioctl.h b/ioctl.h
index 0df2444c..771da231 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -216,7 +216,20 @@ struct btrfs_ioctl_feature_flags {
  */
 struct btrfs_balance_args {
 	__u64 profiles;
-	__u64 usage;
+
+	/*
+	 * usage filter
+	 * BTRFS_BALANCE_ARGS_USAGE with a single value means '0..N'
+	 * BTRFS_BALANCE_ARGS_USAGE_RANGE - range syntax, min..max
+	 */
+	union {
+		__u64 usage;
+		struct {
+			__u32 usage_min;
+			__u32 usage_max;
+		};
+	};
+
 	__u64 devid;
 	__u64 pstart;
 	__u64 pend;