Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753789Ab3JWMt1 (ORCPT ); Wed, 23 Oct 2013 08:49:27 -0400 Received: from mail-wi0-f176.google.com ([209.85.212.176]:43386 "EHLO mail-wi0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753690Ab3JWMt0 (ORCPT ); Wed, 23 Oct 2013 08:49:26 -0400 MIME-Version: 1.0 In-Reply-To: <300471382514034@web11h.yandex.ru> References: <55541379679397@web20h.yandex.ru> <183031382371160@web6m.yandex.ru> <139841382436609@web24g.yandex.ru> <300471382514034@web11h.yandex.ru> Date: Wed, 23 Oct 2013 07:49:24 -0500 Message-ID: Subject: Re: lz4hc compression in UBIFS? From: Brent Taylor To: Konstantin Tokarev Cc: "linux-mtd@lists.infradead.org" , Artem Bityutskiy , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2150 Lines: 55 On Wed, Oct 23, 2013 at 2:40 AM, Konstantin Tokarev wrote: > > > 23.10.2013, 09:26, "Brent Taylor" : >> Konstantin, >> I did my testing with data from /dev/urandom (which I now realize >> wasn't the best choice of data source), but if I use /dev/zero (which >> actually causes data compression to occur), the decompressor fails. I >> don't know the internal workings of the lz4hc compressor or the lz4 >> decompressor. I couldn't find any examples of any code in the kernel >> actually using the compressor. I've cc'ed the maintainers of the >> lz4hc_compress.c to see if they my have some more insight to the >> issue. > > Does decompressor fail for you with the same error messages? > > Have you tried to copy my file to the volume? It looks like minimal test case > for my board, if I remove any line decompressor works fine. > > -- > Regards, > Konstantin Yes, I get the same error, here's a dump from UBIFS when I cat a file filled with data from /dev/zero: UBIFS error (pid 4288): ubifs_decompress: cannot decompress 12 bytes, compressor lz4hc, error -22 UBIFS error (pid 4288): read_block: bad data node (block 0, inode 71) magic 0x6101831 crc 0xff61a078 node_type 1 (data node) group_type 0 (no node group) sqnum 2700 len 60 key (71, data, 0) size 512 compr_typ 3 data size 12 data: 00000000: 1f 00 01 00 ff e8 50 00 00 00 00 00 UBIFS error (pid 4288): do_readpage: cannot read page 0 of inode 71, error -22 cat: /opt/data/zero.bin: Input/output error Steps to reproduce are: 1. Create a file with all zeros: dd if=/dev/zero bs=512 count=1 of=/opt/data/zero.bin 2. Unmount ubifs and detach ubi partition 3. attach ubi partition and mount ubifs 4. cat /opt/data/zero.bin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/