Bug 574266
| Summary: | Data Changes In-Flight After I/O Submission | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Ihab Hamadi <Ihab.Hamadi> |
| Component: | kernel | Assignee: | Red Hat Kernel Manager <kernel-mgr> |
| Status: | CLOSED NOTABUG | QA Contact: | Red Hat Kernel QE team <kernel-qe> |
| Severity: | high | Docs Contact: | |
| Priority: | low | ||
| Version: | 6.0 | CC: | chellwig, christof.schmitt, coughlan, jmoyer, maier, revers, rwheeler, vaios.papadimitriou |
| Target Milestone: | rc | ||
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2011-02-01 12:47:58 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
|
Description
Ihab Hamadi
2010-03-17 01:22:46 UTC
I am seeing a similar problem on internal tests, see http://marc.info/?l=linux-scsi&m=127530531808556&w=2 Adding a debug patch in sd_prep_fn shows that the guard tag does not match the user data on some write requests. I see the problem on the 2.6.34 kernel, but only on the ext2 filesystem, not on ext3/4. Are you testing on RHEL5.4 or just upstream? Thanks! Upstream 2.6.34. Since the above comment mentioned 2.6.33, i wanted to know if this is the same problem. According to the e-mail discussion this is the same problem, and buffers can change while I/O is in flight. I think that this BZ was filed incorrectly against RHEL5.4. Definitely an interesting upstream thread and something that we need to fix in the future. For RHEL5.x or RHEL6.0, we do not support DIF/DIX via file systems. The narrow focus was for support of DIF/DIX for raw devices. Regards, Ric This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux major release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Major release. This request is not yet committed for inclusion. Just for reference, there are three other RHEL 6 BZs related to DIF: Bug 549918 - kernel panic when running xfstests on ext4 over emulated DIF scsi disk This one has a release note for 6.0, indicating that DIF can only be used with O_DIRECT. That BZ also reports a possible bug in scsi_debug that causes a kernel panic when it is used to test DIF. If true, that will be queued for 6.1. Bug 549913 - xfs errors when running xfstests on emulated DIF scsi disk. (closed) Bug 606161 - xfs errors when running xfstests on emulated DIF scsi disk. This BZ is against the Storage Admin Guide, to get the same info that is in the release note into the guide. (In reply to comment #0) > Description of problem: > > Steps to Reproduce: > 4-In terminal 1, run the following: > #dd if=/dev/urandom of=/dev/sda bs=1k seek=100 > 5-In terminal 2, run the following: > #dd if=/dev/urandom of=/dev/sda bs=1k seek=1000 > 6-In terminal 3, run syn periodically (by hand) > #sync Ihab, So, you need to confine your BlockGuard/DIF testing to O_DIRECT. In the above, I believe all you need to do is add oflag=direct to the dd command line. Please try that. You may have access to other tests, like dt, that can also be set to use direct I/O, or you can use raw devices, or XFS in direct I/O mode. We appreciate your effort in testing this. Tom This request was evaluated by Red Hat Product Management for inclusion in the current release of Red Hat Enterprise Linux. Because the affected component is not scheduled to be updated in the current release, Red Hat is unfortunately unable to address this request at this time. Red Hat invites you to ask your support representative to propose this request, if appropriate and relevant, in the next release of Red Hat Enterprise Linux. If you would like it considered as an exception in the current release, please ask your support representative. This request was erroneously denied for the current release of Red Hat Enterprise Linux. The error has been fixed and this request has been re-proposed for the current release. This request was evaluated by Red Hat Product Management for inclusion in the current release of Red Hat Enterprise Linux. Because the affected component is not scheduled to be updated in the current release, Red Hat is unfortunately unable to address this request at this time. Red Hat invites you to ask your support representative to propose this request, if appropriate and relevant, in the next release of Red Hat Enterprise Linux. If you would like it considered as an exception in the current release, please ask your support representative. Thanks for the testing! As Tom noted above, DIF/DIX works only in O_DIRECT mode, so I will close this BZ on the assumption that your tests pass with O_DIRECT. Please reopen if you see issues when using O_DIRECT, thanks! |