bcachefs: Don't do upgrades in nochanges mode

nochanges mode is often used for getting data off of otherwise
nonrecoverable filesystems, which is often because of errors hit during
fsck.

Don't force version upgrade & fsck in nochanges mode, so that it's more
likely to mount.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/recovery.c

@@ -1081,15 +1081,17 @@ int bch2_fs_recovery(struct bch_fs *c)
 		set_bit(BCH_FS_REBUILD_REPLICAS, &c->flags);
 	}
 
-	if (c->sb.version < bcachefs_metadata_version_inode_backpointers) {
-		bch_info(c, "version prior to inode backpointers, upgrade and fsck required");
-		c->opts.version_upgrade	= true;
-		c->opts.fsck		= true;
-		c->opts.fix_errors	= FSCK_OPT_YES;
-	} else if (c->sb.version < bcachefs_metadata_version_subvol_dirent) {
-		bch_info(c, "filesystem version is prior to subvol_dirent - upgrading");
-		c->opts.version_upgrade = true;
-		c->opts.fsck		= true;
+	if (!c->opts.nochanges) {
+		if (c->sb.version < bcachefs_metadata_version_inode_backpointers) {
+			bch_info(c, "version prior to inode backpointers, upgrade and fsck required");
+			c->opts.version_upgrade	= true;
+			c->opts.fsck		= true;
+			c->opts.fix_errors	= FSCK_OPT_YES;
+		} else if (c->sb.version < bcachefs_metadata_version_subvol_dirent) {
+			bch_info(c, "filesystem version is prior to subvol_dirent - upgrading");
+			c->opts.version_upgrade = true;
+			c->opts.fsck		= true;
+		}
 	}
 
 	ret = bch2_blacklist_table_initialize(c);