From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [213.170.72.194] (helo=shelob.oktetlabs.ru) by canuck.infradead.org with esmtp (Exim 4.42 #1 (Red Hat Linux)) id 1CJrXv-0002DR-Fw for linux-mtd@lists.infradead.org; Tue, 19 Oct 2004 06:48:52 -0400 Message-ID: <4174F0F3.7030604@yandex.ru> Date: Tue, 19 Oct 2004 14:48:19 +0400 From: "Artem B. Bityuckiy" MIME-Version: 1.0 To: Ferenc Havasi References: <417156E1.9000009@yandex.ru> <4173AFAE.6060303@inf.u-szeged.hu> <4173B404.6040100@yandex.ru> <4174C8EF.50604@inf.u-szeged.hu> <4174D508.8050508@yandex.ru> <4174E7D3.9050706@inf.u-szeged.hu> In-Reply-To: <4174E7D3.9050706@inf.u-szeged.hu> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-mtd@lists.infradead.org Subject: Re: JFFS2 compression List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Ferenc Havasi wrote: > Now the compression mode is a global thing. It can be configured by > kernelconfig and is the same for every filesystem. There is no reserved > space to store it in the different JFFS2 filesystems (it should need a > new type of node or something like that). It isn't needed to store the default compression mode *on flash*. If you just move the variable jffs2_compression mode to the jffs2_sb_info structure, you will have per-filesystems compression mode. This means, for example, that if user changes (dynamically) the compression mode for one file-system, the compression mode for another file system isn't changed. > > There is plans for the future. One of them: there will be "compression > configurations". This is much more general thing than compression mode. > (contais not only the compression mode but the set of the enabled > compressors and its priority) The user will be able to define different > compressor configuration for files or directories. The description of > these configuration will be stored in a new type of node > (RWCOMPACT_COPY), and the index of the requested configuration will be > stored in the upper 4 bits of 'usercompr' field of jffs2_raw_inode. Great idea! But this is the another (deeper) layer. If a file/directory has the compression mode set, it would be applied. But the *per-filesystem* compression may be used by default (for those files who are not mentioned in your "compression configuration" node). -- Best Regards, Artem B. Bityuckiy, St.-Petersburg, Russia.