From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg0-x234.google.com ([2607:f8b0:400e:c05::234]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1cisp1-0001jo-UO for linux-mtd@lists.infradead.org; Wed, 01 Mar 2017 01:12:53 +0000 Received: by mail-pg0-x234.google.com with SMTP id p5so13316897pga.1 for ; Tue, 28 Feb 2017 17:12:31 -0800 (PST) Date: Wed, 1 Mar 2017 10:12:24 +0900 From: Hyunchul Lee To: Artem Bityutskiy Cc: Richard Weinberger , linux-mtd@lists.infradead.org, Hyunchul Lee , kernel-team@lge.com Subject: Re: [PATCH 0/3] ubifs: add lz4hc compression Message-ID: <20170301011224.GC15972@Hyeoncheol-PC00> References: <1488259008-12510-1-git-send-email-hyc.lee@gmail.com> <1488277025.3583.2.camel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1488277025.3583.2.camel@gmail.com> List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Feb 28, 2017 at 12:17:05PM +0200, Artem Bityutskiy wrote: > On Tue, 2017-02-28 at 14:16 +0900, Hyunchul Lee wrote: > > Another compression type cannot be added any more in respect that > > type of > > ubifs_inode's compr_type is "unsigned:2" and there are 4 compression > > types.  There may be overflow in assignment to compr_type, and > > prevision  > > version of ubifs is trying to decompress file with wrong compression > > type. > > But this is just an in-memory inode structure, and you can change it, > just increase the size of 'compr_type'. yes, it is an in-memory inode. but i think that there can be problem of backward compatibility. for example, if ubifs_ino_node's compr_type is 4 in flash, the previous version of ubifs could misinterpret it as 0, because ubifs_inode's compr_type(2-bit) is assigned ubifs_ino_nodes' compr_type at ubifs_iget. thank you for comment. Hyunchul