From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Masover Subject: Re: silent semantic changes with reiser4 Date: Thu, 26 Aug 2004 13:40:06 -0500 Message-ID: <412E2E86.8050909@slaphack.com> References: <1093536282.5482.6.camel@leto.cs.pocnet.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Rik van Riel , Jamie Lokier , Denis Vlasenko , Christer Weinigel , Spam , Andrew Morton , wichert@wiggy.net, jra@samba.org, torvalds@osdl.org, reiser@namesys.com, hch@lst.de, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, flx@namesys.com, reiserfs-list@namesys.com Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com To: Christophe Saout In-Reply-To: <1093536282.5482.6.camel@leto.cs.pocnet.net> List-Id: linux-fsdevel.vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Christophe Saout wrote: | Yes, the main compound stream unaware applications would see would just | be a writable view of its contents. Probably not trivial to implement | but doable. Not the main stream, I think, but we do need a way to make "eight-stream octopus" files portable. But there needs to be a copy(2) syscall, and apps need to start supporting it. After all, copy-on-write was planned for Reiser4, now 4.1*. And don't anyone dare suggest "userland library". | It should be a simple format. Something simliar to tar. The worst thing Simple, yes. Similar to tar, no. How about a serializer plugin? foo.mp3/serialize (say) should return some single stream which contains all of foo.mp3. It could work for directories as well, recursively, at least on the same filesystem -- you'd back up by doing cp /serialize /backup/20040826 This has two potential problems. One is security -- I want to be able to serialize foo.mp3 without being root, but root doesn't want me to be able to serialize /etc and thus get access to shadow. The second problem is that in order to actually be used for backup, we need snapshots, which are not done yet*. Currently, it'd have to lock the file/directory (recursively), which you don't want to do to entire live filesystems... So, no massive backups of live systems yet, but definitely useful for sending around mp3s and such. | that can happen is people start writing plugins for every existing | compound format out there. It should be the other way around, agree on a | simple compound format and encourage applications to use this one if the | want to use this advantage. For the format, I vote for whatever format we're using at the storage layer. It'd be a lot faster that way, both in execution time (I think) and in development time (I'm sure). Plus, imagine the restore: cat /backup/20040826 > /dev/hda5 resizefs_reiser4 /dev/hda5 * Disclaimer -- all this is "I think, last I checked". -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iQIVAwUBQS4uhngHNmZLgCUhAQKTaw//WCHt0Umgaf0GaMUpEr0PLhiXhFTYQqKV MKgpVt6SjP7lC9k3RbuCnPCLyOJGb9lIqo+Wd+B3b4TcQAQd4OYsSI6WiMPQjxXY OdNnB7/xYkkd/ULw7/7IGcokyc4FRDjhTyOMe4KscQS/6uhdX1dCriCCzVq7iELx u3HLulunHv1bwHbnZ6CyEZdQEr3j8XUu62+IXPTc6hWnfRRCvskV8Y4qyyVd8wFY Kp44TxbJJSzDeWmuI/YYkxVJsPmSoxRLxmw9/B8D72KGNg1SYLnM4ueIc5IV8RH0 kG/o8tzwTRxE/eqfcHP+UBt6yXZR/i84DDogAmJFKP73g9X+U+J5o/kONOBQODhY qY5LUwQu4UjlzXttMxC4NmZPESdUw85DgC/GhTQlsBMYBcmQHmpLAK67qt83+Kg0 1QqGPqJm4HL4weHLNknJ0DukLNKH7Bw5CVg335IwruaoiKUG7HDgthUhA319FCab VvYa+bEfeBEw9RorSE/gWM9Hg73luM7eoSzKc9zHgx++cACTi8SBsTFWqI2FU6DX UyWG5sNPybOiczpPsFu5S5FJBBNM3fLjkfeYgfqxUIjxGTNeUn/g/9I5ShUrCF1o T+3nd1jFxfoehYGkfGB2YLpdeNVBv4EdKK16j39+iducfJrXnRlL1yjdo/Kte2uz tTQZw3uTnhU= =7bBF -----END PGP SIGNATURE-----