btrfs-progs: prepare merging compat feature lists

The features are split to -O and -R but it does not make much sense from
user POV, there are different levels of compatibility but it does not
need to be selected that way. Merge the tables into one but hide it
behind experimental build until the conversion is complete.

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

common/fsfeatures.c

@@ -43,12 +43,22 @@ enum feature_source {
 	RUNTIME_FEATURES,
 };
 
+enum feature_compat {
+	/* Feature is backward compatible, read-write */
+	FEATURE_COMPAT,
+	/* Feature is backward compatible, read-only, filesystem can be mounted */
+	FEATURE_COMPAT_RO,
+	/* Feature is backward incompatible, filesystem cannot be mounted */
+	FEATURE_INCOMPAT
+};
+
 /*
  * Feature stability status and versions: compat <= safe <= default
  */
 struct btrfs_feature {
 	const char *name;
 	u64 flag;
+	enum feature_compat compat;
 	const char *sysfs_name;
 	/*
 	 * Compatibility with kernel of given version. Filesystem can be
@@ -75,14 +85,29 @@ static const struct btrfs_feature mkfs_features[] = {
 	{
 		.name		= "mixed-bg",
 		.flag		= BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS,
+		.compat		= FEATURE_INCOMPAT,
 		.sysfs_name	= "mixed_groups",
 		VERSION_TO_STRING3(compat, 2,6,37),
 		VERSION_TO_STRING3(safe, 2,6,37),
 		VERSION_NULL(default),
 		.desc		= "mixed data and metadata block groups"
-	}, {
+	},
+#if EXPERIMENTAL
+	{
+		.name		= "quota",
+		.flag		= BTRFS_RUNTIME_FEATURE_QUOTA,
+		.compat		= FEATURE_COMPAT_RO,
+		.sysfs_name	= NULL,
+		VERSION_TO_STRING2(compat, 3,4),
+		VERSION_NULL(safe),
+		VERSION_NULL(default),
+		.desc		= "quota support (qgroups)"
+	},
+#endif
+	{
 		.name		= "extref",
 		.flag		= BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF,
+		.compat		= FEATURE_INCOMPAT,
 		.sysfs_name	= "extended_iref",
 		VERSION_TO_STRING2(compat, 3,7),
 		VERSION_TO_STRING2(safe, 3,12),
@@ -91,6 +116,7 @@ static const struct btrfs_feature mkfs_features[] = {
 	}, {
 		.name		= "raid56",
 		.flag		= BTRFS_FEATURE_INCOMPAT_RAID56,
+		.compat		= FEATURE_INCOMPAT,
 		.sysfs_name	= "raid56",
 		VERSION_TO_STRING2(compat, 3,9),
 		VERSION_NULL(safe),
@@ -99,6 +125,7 @@ static const struct btrfs_feature mkfs_features[] = {
 	}, {
 		.name		= "skinny-metadata",
 		.flag		= BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA,
+		.compat		= FEATURE_INCOMPAT,
 		.sysfs_name	= "skinny_metadata",
 		VERSION_TO_STRING2(compat, 3,10),
 		VERSION_TO_STRING2(safe, 3,18),
@@ -107,14 +134,29 @@ static const struct btrfs_feature mkfs_features[] = {
 	}, {
 		.name		= "no-holes",
 		.flag		= BTRFS_FEATURE_INCOMPAT_NO_HOLES,
+		.compat		= FEATURE_INCOMPAT,
 		.sysfs_name	= "no_holes",
 		VERSION_TO_STRING2(compat, 3,14),
 		VERSION_TO_STRING2(safe, 4,0),
 		VERSION_TO_STRING2(default, 5,15),
 		.desc		= "no explicit hole extents for files"
-	}, {
+	},
+#if EXPERIMENTAL
+	{
+		.name		= "free-space-tree",
+		.flag		= BTRFS_RUNTIME_FEATURE_FREE_SPACE_TREE,
+		.compat		= FEATURE_COMPAT_RO,
+		.sysfs_name = "free_space_tree",
+		VERSION_TO_STRING2(compat, 4,5),
+		VERSION_TO_STRING2(safe, 4,9),
+		VERSION_TO_STRING2(default, 5,15),
+		.desc		= "free space tree (space_cache=v2)"
+	},
+#endif
+	{
 		.name		= "raid1c34",
 		.flag		= BTRFS_FEATURE_INCOMPAT_RAID1C34,
+		.compat		= FEATURE_INCOMPAT,
 		.sysfs_name	= "raid1c34",
 		VERSION_TO_STRING2(compat, 5,5),
 		VERSION_NULL(safe),
@@ -125,6 +167,7 @@ static const struct btrfs_feature mkfs_features[] = {
 	{
 		.name		= "zoned",
 		.flag		= BTRFS_FEATURE_INCOMPAT_ZONED,
+		.compat		= FEATURE_INCOMPAT,
 		.sysfs_name	= "zoned",
 		VERSION_TO_STRING2(compat, 5,12),
 		VERSION_NULL(safe),
@@ -132,10 +175,23 @@ static const struct btrfs_feature mkfs_features[] = {
 		.desc		= "support zoned devices"
 	},
 #endif
+#if EXPERIMENTAL
+	{
+		.name		= "block-group-tree",
+		.flag		= BTRFS_RUNTIME_FEATURE_BLOCK_GROUP_TREE,
+		.compat		= FEATURE_COMPAT_RO,
+		.sysfs_name = "block_group_tree",
+		VERSION_TO_STRING2(compat, 6,0),
+		VERSION_NULL(safe),
+		VERSION_NULL(default),
+		.desc		= "block group tree to reduce mount time"
+	},
+#endif
 #if EXPERIMENTAL
 	{
 		.name		= "extent-tree-v2",
 		.flag		= BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2,
+		.compat		= FEATURE_INCOMPAT,
 		.sysfs_name	= "extent_tree_v2",
 		VERSION_TO_STRING2(compat, 5,15),
 		VERSION_NULL(safe),
@@ -147,6 +203,7 @@ static const struct btrfs_feature mkfs_features[] = {
 	{
 		.name = "list-all",
 		.flag = BTRFS_FEATURE_LIST_ALL,
+		.compat	= FEATURE_INCOMPAT,
 		.sysfs_name = NULL,
 		VERSION_NULL(compat),
 		VERSION_NULL(safe),
@@ -185,6 +242,7 @@ static const struct btrfs_feature runtime_features[] = {
 	{
 		.name = "list-all",
 		.flag = BTRFS_FEATURE_LIST_ALL,
+		.compat	= FEATURE_COMPAT_RO,
 		.sysfs_name = NULL,
 		VERSION_NULL(compat),
 		VERSION_NULL(safe),