bcache-tools: upgrade super block versions for feature sets

This patch upgrades super block versions for adding feature sets into
struct cache_sb_disk,
128         __u64                   feature_compat;
129         __u64                   feature_incompat;
130         __u64                   feature_ro_compat;

With the feature set flags, it will be convenient to add new features
without upgrade super block version again (at least for a long time).

The new added versions are,
- BCACHE_SB_VERSION_CDEV_WITH_FEATURES for cache device super block
- BCACHE_SB_VERSION_BDEV_WITH_FEATURES for backing device super block

The feature set flags are also added into the in-memory super block
struct cache_sb. The feature sets conversion between cache_sb_disk and
cache_sb also added into to_cache_sb() and to_cache_sb_disk().

Some feature sets related macros are also added into bcache.h, and a new
file feature.c is added for future new features record and display.

Signed-off-by: Coly Li <colyli@suse.de>

4 files changed, 118 insertions, 3 deletions

diff --git a/Makefile b/Makefile
index b4546a14..8b87a676 100644
--- a/Makefile
+++ b/Makefile
@@ -38,4 +38,4 @@ bcache-register: bcache-register.o
 bcache: CFLAGS += `pkg-config --cflags blkid uuid smartcols`
 bcache: LDLIBS += `pkg-config --libs blkid uuid smartcols`
 bcache: CFLAGS += -std=gnu99
-bcache: crc64.o lib.o make.o zoned.o
+bcache: crc64.o lib.o make.o zoned.o features.o
diff --git a/bcache.h b/bcache.h
index 250da9d4..9d969e12 100644
--- a/bcache.h
+++ b/bcache.h
@@ -29,12 +29,16 @@ static const char bcache_magic[] = {
  * Version 2: Seed pointer into btree node checksum
  * Version 3: Cache device with new UUID format
  * Version 4: Backing device with data offset
+ * Version 5: Cache adn backing devices with compat/incompat/ro_compat
+ *            feature sets
  */
 #define BCACHE_SB_VERSION_CDEV			0
 #define BCACHE_SB_VERSION_BDEV			1
 #define BCACHE_SB_VERSION_CDEV_WITH_UUID	3
 #define BCACHE_SB_VERSION_BDEV_WITH_OFFSET	4
-#define BCACHE_SB_MAX_VERSION			4
+#define BCACHE_SB_VERSION_CDEV_WITH_FEATURES	5
+#define BCACHE_SB_VERSION_BDEV_WITH_FEATURES	6
+#define BCACHE_SB_MAX_VERSION			6
 
 #define SB_SECTOR		8
 #define SB_LABEL_SIZE		32
@@ -59,7 +63,11 @@ struct cache_sb_disk {
 	__le64			flags;
 	__le64			seq;
 
-	__le64			pad[8];
+	__le64			feature_compat;
+	__le64			feature_incompat;
+	__le64			feature_ro_compat;
+
+	__le64			pad[5];
 
 	union {
 	struct {
@@ -116,6 +124,10 @@ struct cache_sb {
 	__u64			flags;
 	__u64			seq;
 
+	__u64			feature_compat;
+	__u64			feature_incompat;
+	__u64			feature_ro_compat;
+
 	union {
 	struct {
 		/* Cache devices */
@@ -180,4 +192,73 @@ uint64_t crc64(const void *data, size_t len);
 #define csum_set(i)							\
 	crc64(((void *) (i)) + 8, ((void *) end(i)) - (((void *) (i)) + 8))
 
+/* Feature set definition */
+
+#define BCH_FEATURE_COMPAT	0
+#define BCH_FEATURE_RO_COMPAT	1
+#define BCH_FEATURE_INCOMPAT	2
+#define BCH_FEATURE_TYPE_MASK	0x03
+
+#define BCH_FEATURE_COMPAT_SUUP		0
+#define BCH_FEATURE_INCOMPAT_SUUP	0
+#define BCH_FEATURE_RO_COMPAT_SUUP	0
+
+#define BCH_HAS_COMPAT_FEATURE(sb, mask) \
+		((sb)->feature_compat & (mask))
+#define BCH_HAS_RO_COMPAT_FEATURE(sb, mask) \
+		((sb)->feature_ro_compat & (mask))
+#define BCH_HAS_INCOMPAT_FEATURE(sb, mask) \
+		((sb)->feature_incompat & (mask))
+
+#define BCH_FEATURE_COMPAT_FUNCS(name, flagname) \
+static inline int bch_has_feature_##name(struct cache_sb *sb) \
+{ \
+	return (((sb)->feature_compat & \
+		BCH##_FEATURE_COMPAT_##flagname) != 0); \
+} \
+static inline void bch_set_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_compat |= \
+		BCH##_FEATURE_COMPAT_##flagname; \
+} \
+static inline void bch_clear_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_compat &= \
+		~BCH##_FEATURE_COMPAT_##flagname; \
+}
+
+#define BCH_FEATURE_RO_COMPAT_FUNCS(name, flagname) \
+static inline int bch_has_feature_##name(struct cache_sb *sb) \
+{ \
+	return (((sb)->feature_ro_compat & \
+		BCH##_FEATURE_RO_COMPAT_##flagname) != 0); \
+} \
+static inline void bch_set_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_ro_compat |= \
+		BCH##_FEATURE_RO_COMPAT_##flagname; \
+} \
+static inline void bch_clear_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_ro_compat &= \
+		~BCH##_FEATURE_RO_COMPAT_##flagname; \
+}
+
+#define BCH_FEATURE_INCOMPAT_FUNCS(name, flagname) \
+static inline int bch_has_feature_##name(struct cache_sb *sb) \
+{ \
+	return (((sb)->feature_incompat & \
+		BCH##_FEATURE_INCOMPAT_##flagname) != 0); \
+} \
+static inline void bch_set_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_incompat |= \
+		BCH##_FEATURE_INCOMPAT_##flagname; \
+} \
+static inline void bch_clear_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_incompat &= \
+		~BCH##_FEATURE_INCOMPAT_##flagname; \
+}
+
 #endif
diff --git a/features.c b/features.c
new file mode 100644
index 00000000..a1c9884d
--- /dev/null
+++ b/features.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: Coly Li <colyli@suse.de>
+ *
+ * Inspired by e2fsprogs features compat/incompat/ro_compat
+ * related code.
+ */
+#include <stdbool.h>
+#include <stdint.h>
+#include <sys/types.h>
+
+#include "bcache.h"
+
+struct feature {
+	int		compat;
+	unsigned int	mask;
+	const char	*string;
+};
+
+static struct feature feature_list[] = {
+	{0, 0, 0 },
+};
diff --git a/lib.c b/lib.c
index 9a2fa265..dcf752c1 100644
--- a/lib.c
+++ b/lib.c
@@ -730,6 +730,12 @@ struct cache_sb *to_cache_sb(struct cache_sb *sb,
 			sb->d[i]= le64_to_cpu(sb_disk->d[i]);
 	}
 
+	if (sb->version >= BCACHE_SB_VERSION_CDEV_WITH_FEATURES) {
+		sb->feature_compat = le64_to_cpu(sb_disk->feature_compat);
+		sb->feature_incompat = le64_to_cpu(sb_disk->feature_incompat);
+		sb->feature_ro_compat = le64_to_cpu(sb_disk->feature_ro_compat);
+	}
+
 	return sb;
 }
 
@@ -772,5 +778,11 @@ struct cache_sb_disk *to_cache_sb_disk(struct cache_sb_disk *sb_disk,
 			sb_disk->d[i] = cpu_to_le64(sb->d[i]);
 	}
 
+	if (sb->version >= BCACHE_SB_VERSION_CDEV_WITH_FEATURES) {
+		sb_disk->feature_compat = cpu_to_le64(sb->feature_compat);
+		sb_disk->feature_incompat = cpu_to_le64(sb->feature_incompat);
+		sb_disk->feature_ro_compat = cpu_to_le64(sb->feature_ro_compat);
+	}
+
 	return sb_disk;
 }