From: Albino B Neto Subject: Re: [GIT PULL] Ext3 removal, quota & udf fixes Date: Wed, 2 Sep 2015 00:30:39 -0300 Message-ID: References: <20150831061920.GA2751@quack.suse.cz> <55E4D5DE.2030709@gmail.com> <55E5FF01.2000304@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Raymond Jennings , Linus Torvalds , Jan Kara , LKML , "linux-ext4@vger.kernel.org" , linux-fsdevel To: Austin S Hemmelgarn Return-path: In-Reply-To: <55E5FF01.2000304@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org 2015-08-31 23:53 GMT-03:00 Theodore Ts'o : > Yes, you can go back to ext3-only. In fact, we do *not* automatically > upgrade the file system to use ext4-specific features. > >> So it's not just a "you can use ext4 instead" issue. Can you do that >> *without* then forcing an upgrade forever on that partition? I'm not >> sure the ext4 people are really even willing to guarantee that kind of >> backwards compatibility. > > Actually, we do guarantee this. It's considered poor form to > automatically change the superblock to add new file system features in > a way that would break the ability for the user to roll back to an > older kernel. This isn't just for ext3->ext4, but for new ext4 > features such as metadata checksumming. The user has to explicitly > enable the feature using "tune2fs -O new_feature /dev/sdXX". Yeah! 2015-09-01 16:39 GMT-03:00 Austin S Hemmelgarn : > NO, it is not logical. A vast majority of Android smartphones in the wild > use ext2, as do a very significant portion of embedded systems that don't > have room for the few hundred kilobytes of extra code that the ext4 driver > has in comparison to ext2. Ext2 portion embedded and Ext3 many machines. -- Albino B Neto www.bino.us "Debian. Freedom to code. Code to freedom!" faw