On Mon, Jul 12, 2021 at 05:43:14PM +0200, Jan Kara wrote: > Enable orphan_file feature by default in larger filesystems. Since the > feature is COMPAT, older kernels will just ignore it and happily work > with the filesystem as well. > > Signed-off-by: Jan Kara <jack@xxxxxxx> We'll need to decide whether we want to enable this by default, at least initially. The general practice has been to not enable new kernel functionality right away by default. It's true that older kernels will ignore the feature if they aren't orphan_file aware; however, we if have a file system which is created with orphan_file eanbled, but that file system with the orphan_file feature is made available to a system which is running an orphan_file-aware kernel, but the distro hadn't picked up the a version e2fsprogs which is orphan_file-aware. This might happen if the file system was created on one system, and then it gets connected to an system w/o a new version of e2fsprogs (e.g. via fibre channel, iscsi, AWS EBS, GCE PD, etc), then could be a surprise to the user. So that's something for us to discuss. In the shorter term, there's another problem I've notied, which is if we add this to mke2fs.conf, and the user runs: mke2fs -t ext4 -O ^has_journal foo.img 1G mke2fs will fail mid-way through the mkfs process with the error message, "mke2fs: cannot set orphan_file flag without a journal". This represents a regression, and if we don't want to drop orphan_file from the default feature set in mke2fs.conf, I think we'll need to check for the case where the file system doesn't have a journal, and only fail when the user has explicitly requested orphan_file on the command line. But if orphan_file is a default as defined in mke2fs.conf, and the journal is not present for whatever reaseon, we need to silently disable the orphan_file feature. (Also note that to avoid user confusion, we should refer to orphan_file as a "feature" instead of a "flag". Even for things like "orphan_present" or "recovery_needed" it is probably clearer to call them features, simply because it makes it easier for system adminsitrators and developers to be able to find the "flag" location.) Cheers, - Ted
