bcachefs: bcachefs_metadata_version_major_minor

This introduces major/minor versioning to the superblock version number.
Major version number changes indicate incompatible releases; we can move
forward to a new major version number, but not backwards. Minor version
numbers indicate compatible changes - these add features, but can still
be mounted and used by old versions.

With the recent patches that make it possible to roll out new btrees and
key types without breaking compatibility, we should be able to roll out
most new features without incompatible changes.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 49 insertions, 14 deletions

diff --git a/fs/bcachefs/recovery.c b/fs/bcachefs/recovery.c
index 3b9120bd3603..17ffac089a5d 100644
--- a/fs/bcachefs/recovery.c
+++ b/fs/bcachefs/recovery.c
@@ -1111,31 +1111,66 @@ static int bch2_fs_upgrade_for_subvolumes(struct bch_fs *c)
 
 static void check_version_upgrade(struct bch_fs *c)
 {
-	unsigned version = c->sb.version_upgrade_complete ?: c->sb.version;
+	unsigned latest_compatible = bch2_version_compatible(c->sb.version);
+	unsigned latest_version	= bcachefs_metadata_version_current;
+	unsigned old_version = c->sb.version_upgrade_complete ?: c->sb.version;
+	unsigned new_version = 0;
+
+	if (old_version < bcachefs_metadata_required_upgrade_below) {
+		if (c->opts.version_upgrade == BCH_VERSION_UPGRADE_incompatible ||
+		    latest_compatible < bcachefs_metadata_required_upgrade_below)
+			new_version = latest_version;
+		else
+			new_version = latest_compatible;
+	} else {
+		switch (c->opts.version_upgrade) {
+		case BCH_VERSION_UPGRADE_compatible:
+			new_version = latest_compatible;
+			break;
+		case BCH_VERSION_UPGRADE_incompatible:
+			new_version = latest_version;
+			break;
+		case BCH_VERSION_UPGRADE_none:
+			new_version = old_version;
+			break;
+		}
+	}
 
-	if (version < bcachefs_metadata_required_upgrade_below ||
-	    (version < bcachefs_metadata_version_current &&
-	     c->opts.version_upgrade != BCH_VERSION_UPGRADE_none)) {
+	if (new_version > old_version) {
 		struct printbuf buf = PRINTBUF;
 
-		if (version != c->sb.version) {
-			prt_str(&buf, "version upgrade to ");
+		if (old_version < bcachefs_metadata_required_upgrade_below)
+			prt_str(&buf, "Version upgrade required:\n");
+
+		if (old_version != c->sb.version) {
+			prt_str(&buf, "Version upgrade from ");
+			bch2_version_to_text(&buf, c->sb.version_upgrade_complete);
+			prt_str(&buf, " to ");
 			bch2_version_to_text(&buf, c->sb.version);
-			prt_str(&buf, " incomplete:\n");
+			prt_str(&buf, " incomplete\n");
 		}
 
-		prt_str(&buf, "version ");
-		bch2_version_to_text(&buf, version);
-		prt_str(&buf, " prior to ");
-		bch2_version_to_text(&buf, bcachefs_metadata_required_upgrade_below);
-		prt_str(&buf, ", upgrade and fsck required");
+		prt_printf(&buf, "Doing %s version upgrade from ",
+			   BCH_VERSION_MAJOR(old_version) != BCH_VERSION_MAJOR(new_version)
+			   ? "incompatible" : "compatible");
+		bch2_version_to_text(&buf, old_version);
+		prt_str(&buf, " to ");
+		bch2_version_to_text(&buf, new_version);
+		prt_newline(&buf);
+
+		prt_str(&buf, "fsck required");
 
 		bch_info(c, "%s", buf.buf);
-		printbuf_exit(&buf);
 
 		c->opts.fsck		= true;
 		c->opts.fix_errors	= FSCK_OPT_YES;
-		set_bit(BCH_FS_VERSION_UPGRADE, &c->flags);
+
+		mutex_lock(&c->sb_lock);
+		c->disk_sb.sb->version = cpu_to_le16(new_version);
+		c->disk_sb.sb->features[0] |= cpu_to_le64(BCH_SB_FEATURES_ALL);
+		mutex_unlock(&c->sb_lock);
+
+		printbuf_exit(&buf);
 	}
 }