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

@@ -1081,6 +1081,7 @@ int bch2_fs_recovery(struct bch_fs *c)
 		set_bit(BCH_FS_REBUILD_REPLICAS, &c->flags);
 	}
 
+	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;
@@ -1091,6 +1092,7 @@ int bch2_fs_recovery(struct bch_fs *c)
 			c->opts.version_upgrade = true;
 			c->opts.fsck		= true;
 		}
+	}
 
 	ret = bch2_blacklist_table_initialize(c);
 	if (ret) {