Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 11 Aug 2003 09:55:18 -0600 | From | Andreas Dilger <> | Subject | Re: [RFC] file extents for EXT3 |
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On Aug 11, 2003 08:53 -0400, Jeff Garzik wrote: > Changing the underlying disk format without bumping the filesystem > revision is a hugely bad idea. I disagreed with merging htree (even > though its backward compat) without bumping the filesystem version, too. > > Vendors, distributors, OEMs, etc. all test against existing on-disk > formats, when they release their products. When the filesystem format > for an existing filesystem, in production, changes underneath them, they > tend to get worried and annoyed. So, to all ext developers, > > Please add <it> to ext4 not ext3!
Ext2/3 uses feature flags instead of version numbers to indicate such changes. Version numbers are a poor way of indicating whether a change is compatible or not compared to feature flags. For example, if you bump the minor number to indicate a "compatible" change it means that any code that pretends to support version x.y features also needs to support all features <= y and all features <= x.
If you really want to have a feature number to be happy, just think of
s.feature_incompat.s_feature_ro_compat.s_feature_compat
as something like a version number and you will nearly be happy.
Cheers, Andreas -- Andreas Dilger http://sourceforge.net/projects/ext2resize/ http://www-mddsp.enel.ucalgary.ca/People/adilger/
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