From: "Juergens Dirk (CM-AI/ECO2)" Subject: AW: AW: AW: ext4 filesystem bad extent error review Date: Fri, 3 Jan 2014 19:56:45 +0100 Message-ID: References: <20140102184211.GC10870@thunk.org> <52C6F28A.6060706@redhat.com> <52C70610.4010907@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: "linux-ext4@vger.kernel.org" To: Eric Sandeen , Theodore Ts'o , "Huang Weller (CM/ESW12-CN)" Return-path: Received: from smtp6-v.fe.bosch.de ([139.15.237.11]:54919 "EHLO smtp6-v.fe.bosch.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751158AbaACS4y convert rfc822-to-8bit (ORCPT ); Fri, 3 Jan 2014 13:56:54 -0500 In-Reply-To: <52C70610.4010907@redhat.com> Content-Language: de-DE Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Jan 03, 2014 at 19:49, Eric Sandeen wrote >=20 > On 1/3/14, 12:45 PM, Juergens Dirk (CM-AI/ECO2) wrote: > > > > On Thu, Jan 03, 2014 at 19:24, Eric Sandeen wrote > >> > >> On 1/3/14, 10:29 AM, Juergens Dirk (CM-AI/ECO2) wrote: > >>> So, I think there _might_ be a kernel bug, but it could be also a > >> problem > >>> related to the particular type of eMMC. We did not observe the sa= me > >> issue > >>> in previous tests with another type of eMMC from another supplier= , > >> but this > >>> was with an older kernel patch level and with another HW design. > >>> > >>> Regarding a possible kernel bug: Is there any chance that the > invalid > >>> ee_len or ee_start are returned by, e.g., the block allocator ? > >>> If so, can we try to instrument the code to get suitable traces ? > >>> Just to see or to exclude that the corrupted inode is really > written > >>> to the eMMC ? > >> > >> From your description it does sound possible that it's a kernel bu= g. > >> Adding testcases to the code to catch it before it hits the journa= l > >> might be helpful - but then maybe this is something getting > overwritten > >> after the fact - hard to say. > >> > >> Can you share more details of the test you are running? Or maybe > even > >> the test itself? > > > > Yes, for sure, we can. Weller, please provide additional details > > or corrections. > > > > In short: > > Basically we use an automated cyclic test writing many small > > (some kBytes) files with CRC checksums for easy consistency check > > into a separate test partition. Files also contain meta information > > like filename, sequence number and a random number to allow to > identify > > from block device image dumps, if we just see a fragment of an old > > deleted file or a still valid one. > > > > Each test loop looks like this: >=20 > 0) mkfs the filesystem - with what options? How big? Here we do need the details from Weller, cause=20 he has done all this.=20 >=20 > > 1) Boot the device after power on or reset > > 2) Do fsck -n BEFORE mounting > > 2 a) (optional) binary dump of the journal > > 3) Mount test partition >=20 > Again with what options, if any? Details again have to be given by Weller, sorry. >=20 > > 4) File content check for all files from prev. loop > > 5) erase all files from previous loop > > 6) start writing hundreds/thousands of test files > > in multiple directories with several threads >=20 > I guess this is where we might need more details in order, > to try to recreate the failure, but perhaps > this is not a case where you can simply share the IO > generation utility...? I think we can share the code, please let me check on Monday. >=20 > Thanks, > -Eric >=20 > > 7) after random time cut the power or do soft reset > > > > If 2), 3), 4) or 5) fails, stop test. > > > > We are running the test usually with kind of transaction > > safe handling, i.e. use fsync/rename, to avoid zero length files > > or file fragments. > > > >> > >> I've used a test framework in the past to simulate resets w/o > needing > >> to reset the box, and do many journal replays very quickly. It'd = be > >> interesting to run it using your testcase. > >> > >> Thanks, > >> -Eric > > > > Mit freundlichen Gr=FC=DFen / Best regards > > > > Dirk Juergens > > > > Robert Bosch Car Multimedia GmbH > > Mit freundlichen Gr=FC=DFen / Best regards Dirk Juergens Robert Bosch Car Multimedia GmbH -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html