Bug 136398
| Summary: | NFS direct reads don't flush dirty cached pages | ||||||
|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 3 | Reporter: | Chuck Lever <cel> | ||||
| Component: | kernel | Assignee: | Steve Dickson <steved> | ||||
| Status: | CLOSED ERRATA | QA Contact: | Brian Brock <bbrock> | ||||
| Severity: | medium | Docs Contact: | |||||
| Priority: | medium | ||||||
| Version: | 3.0 | CC: | davej, k.georgiou, petrides, riel, steved | ||||
| Target Milestone: | --- | ||||||
| Target Release: | --- | ||||||
| Hardware: | All | ||||||
| OS: | Linux | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | Doc Type: | Bug Fix | |||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2005-05-18 13:28:18 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: | |||||||
| Attachments: |
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Created attachment 105463 [details]
proposed patch
I'm hopeful that this will make into RHEL3-U5
A fix for this problem has just been committed to the RHEL3 U5 patch pool this evening (in kernel version 2.4.21-25.1.EL). An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2005-294.html |
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.2) Gecko/20040803 Description of problem: The NFS direct I/O patch applied to RHEL 3.0 update 3 has a minor bug that was found during testing with fsx-odirect. The fix is in function nfs_file_direct_IO in fs/nfs/direct.c: retval = filemap_fdatasync(mapping); if (retval == 0) - retval = fsync_inode_data_buffers(inode); + retval = nfs_wb_all(inode); if (retval == 0) retval = filemap_fdatawait(mapping); fsync_inode_data_buffers() comes from the normal direct I/O path, but since NFS doesn't use inode data buffers, it is a no-op in the NFS direct I/O path. nfs_wb_all is the correct function to call here. Note that there are no real applications I'm aware of that access a file via direct I/O and writable map simultaneously. Version-Release number of selected component (if applicable): kernel-2.4.21-20.EL How reproducible: Always Steps to Reproduce: 1. mmap a file in NFS, and open it with O_DIRECT 2. dirty the map with just a few bytes, then read from the O_DIRECT file descriptor in quick succession Actual Results: I did this with fsx-odirect. It dirtied 92KB of the map, and the NFS client flushed only 64KB of the dirty pages before the direct read operation. Expected Results: All 92KB should have been written to the server before the direct read operation. Additional info: The problem occurs because nfs_strategy only pushes writes out in "wsize" chunks. nfs_wb_all pushes everything no matter how many NFS write operations it takes.