From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261500AbTLHSYI (ORCPT ); Mon, 8 Dec 2003 13:24:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261522AbTLHSYH (ORCPT ); Mon, 8 Dec 2003 13:24:07 -0500 Received: from fw.osdl.org ([65.172.181.6]:22937 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S261500AbTLHSXo (ORCPT ); Mon, 8 Dec 2003 13:23:44 -0500 Subject: Re: [PATCH linux-2.6.0-test10-mm1] dio-read-race-fix From: Daniel McNeil To: Janet Morgan Cc: Suparna Bhattacharya , Badari Pulavarty , "linux-aio@kvack.org" , Linux Kernel Mailing List , Andrew Morton In-Reply-To: <1070674185.1929.9.camel@ibm-c.pdx.osdl.net> References: <3FCD4B66.8090905@us.ibm.com> <1070674185.1929.9.camel@ibm-c.pdx.osdl.net> Content-Type: text/plain Organization: Message-Id: <1070907814.707.2.camel@ibm-c.pdx.osdl.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.2 (1.2.2-5) Date: 08 Dec 2003 10:23:34 -0800 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org My patch did not fix the problem. :( The tests over the weekend reported bad data. The sampling of the i_size after dropping i_sem still looks wrong to me. I will keep looking and see if I can find another problem. Daniel On Fri, 2003-12-05 at 17:29, Daniel McNeil wrote: > Janet, > > I think I found the problem that is causing the dio reads to get > unintialized data with buffer writes. i_size is sampled after > i_sem is dropped and after the i/o have completed. i_size could > have changed in the mean time. This patch samples i_size before > dropping i_sem. I'll leave the test running over the weekend to > verify. > > Daniel > > On Tue, 2003-12-02 at 18:33, Janet Morgan wrote: > > Hi Suparna, Daniel, > > > > Just wanted to let you know that I seem to be hitting a failure when I > > run the testcase (attached) that Stephen Tweedie wrote to expose the DIO > > races (the testcase issues buffered writes and dio reads). I'm trying to > > debug the failure, but I know it will be slow going for me. > > > > I hit the problem when I run multiple instances of the test against > > the same filesystem (I do specify a unique file for each instance of > > the test). I normally run about 6 instances of the test, e.g., > > "direct_read_under foo1", "direct_read_under foo2", etc. The test > > runs in an infinite loop until a data mis-compare is detected. > > I have not been able to reproduce the failure when I restrict each > > instance of the test to its own filesystem. > > > > I've tried running with the combinations below and I eventually > > get a failure in each case. I assume all but the last combo includes > > the critical aio/dio fixes for the associated base. > > > > Combinations tested: > > > > Daniel's latest: > > 2.6.0-test9-mm5 + > > aio-dio-fallback-bio_count-race.patch + > > direct-io-memleak-fix.patch > > > > Suparna's latest: > > 2.6.0-test9-mm5 + > > Suparna's current patches: > > > > http://marc.theaimsgroup.com/?l=linux-aio&m=106983304420570&w=2 + > > > > http://marc.theaimsgroup.com/?l=linux-kernel&m=106904658121299&w=2 + > > direct-io-memleak-fix.patch > > > > stock linux-2.6.0-test9 plus: > > aio-refcnt.patch + > > dio-aio-fixes.patch + > > dio-aio-fixes-fixes.patch + > > O_DIRECT-race-fixes-rollup.patch > > > > stock linux-2.6.0-test11 plus: > > O_DIRECT-race-fixes-rollup.patch > > > > Thanks, > > -Janet > > > > ______________________________________________________________________ > > > > #define _XOPEN_SOURCE 600 > > #define _GNU_SOURCE > > > > #include > > #include > > #include > > #include > > #include > > #include > > #include > > #include > > > > #define BIGSIZE 128*1024*1024 > > #define READSIZE 32*1024*1024 > > #define WRITESIZE 32*1024*1024 > > > > int pagesize; > > char *iobuf; > > > > void assert(const char *what, int assertion) > > { > > if (assertion) > > return; > > perror(what); > > exit(1); > > } > > > > void do_buffered_writes(int fd, int pattern) > > { > > int rc; > > int offset; > > > > memset(iobuf, pattern, WRITESIZE); > > for (offset = 0; offset+WRITESIZE <= BIGSIZE; offset += WRITESIZE) { > > rc = pwrite(fd, iobuf, WRITESIZE, offset); > > assert("pwrite", rc >= 0); > > if (rc != WRITESIZE) { > > fprintf(stderr, "short write (%d out of %d)\n", > > rc, WRITESIZE); > > exit(1); > > } > > fsync(fd); > > } > > } > > > > int do_direct_reads(char *filename) > > { > > int fd; > > int offset; > > int rc, i; > > int *p; > > > > fd = open(filename, O_DIRECT|O_RDONLY, 0); > > assert("open", fd >= 0); > > > > for (offset = 0; offset+READSIZE <= BIGSIZE; offset += READSIZE) { > > rc = pread(fd, iobuf, READSIZE, offset); > > assert("pread", rc >= 0); > > if (rc != READSIZE) { > > fprintf(stderr, "short read (%d out of %d)\n", > > rc, READSIZE); > > exit(1); > > } > > for (i=0, p=(int *)iobuf; i > if (*p) { > > fprintf(stderr, > > "Found data (%08x) at offset %d+%d\n", > > *p, offset, i); > > return 1; > > } > > p++; > > } > > } > > return 0; > > } > > > > int main(int argc, char *argv[]) > > { > > char *filename; > > int fd; > > int pid; > > int err; > > int pass = 0; > > int bufsize; > > > > if (argc != 2) { > > fprintf(stderr, "Needs a filename as an argument.\n"); > > exit(1); > > } > > > > filename = argv[1]; > > > > pagesize = getpagesize(); > > bufsize = READSIZE; > > if (WRITESIZE > READSIZE) > > bufsize = WRITESIZE; > > err = posix_memalign((void**) &iobuf, pagesize, bufsize); > > if (err) { > > fprintf(stderr, "Error allocating %d aligned bytes.\n", bufsize); > > exit(1); > > } > > > > fd = open(filename, O_CREAT|O_TRUNC|O_RDWR, 0666); > > assert("open", fd >= 0); > > > > do { > > printf("Pass %d...\n", ++pass); > > > > assert("ftruncate", ftruncate(fd, BIGSIZE) == 0); > > fsync(fd); > > > > pid = fork(); > > assert("fork", pid >= 0); > > > > if (!pid) { > > do_buffered_writes(fd, 0); > > exit(0); > > } > > > > err = do_direct_reads(filename); > > > > wait4(pid, NULL, WNOHANG, 0); > > > > if (err) > > break; > > > > /* Fill the file with a known pattern so that the blocks > > * on disk can be detected if they become exposed. */ > > do_buffered_writes(fd, 1); > > fsync(fd); > > > > assert("ftruncate", ftruncate(fd, 0) == 0); > > fsync(fd); > > } while (1); > > > > return err; > > } > >