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Bug 501082

Summary:	RHEL5.4 ext4: backport corruption fixes from .30
Product:	Red Hat Enterprise Linux 5	Reporter:	Eric Sandeen <esandeen>
Component:	kernel	Assignee:	Eric Sandeen <esandeen>
Status:	CLOSED ERRATA	QA Contact:	Red Hat Kernel QE team <kernel-qe>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	5.4	CC:	dzickus, emcnabb, imatusov, k.georgiou, mgahagan, rwheeler, syeghiay
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:	2009-09-02 08:45:09 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 Eric Sandeen 2009-05-15 21:53:30 UTC

A handful of corruption fixes are in the .30 tree and should be backported to the ext4 tech preview in RHEL5.4:

2a8964d63d50dd2d65d71d342bc7fb6ef4117614
ext4: Clear the unwritten buffer_head flag after the extent is initialized

33b9817e2ae097c7b8d256e3510ac6c54fc6d9d0
ext4: Use a fake block number for delayed new buffer_head

2ec0ae3acec47f628179ee95fe2c4da01b5e9fc4
ext4: Fix race in ext4_inode_info.i_cached_extent

9c1ee184a30394e54165fa4c15923cabd952c106
ext4: Fix sub-block zeroing for writes into preallocated extents

These are in F11 as well, as of today.

Comment 1 RHEL Program Management 2009-05-15 21:59:07 UTC

This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update
release.

Comment 2 Eric Sandeen 2009-05-18 16:02:43 UTC

Actually, I'm going to ask for blocker on this.  

There are already upstream patches for this issue, and I just merged them to F11.

There are a couple issues here, but one is trivial to reproduce; a partial-block write into a preallocated block will expose garbage:

[root@bear-05 test]# touch testfile
[root@bear-05 test]# /root/fallocate -l 4096 testfile
[root@bear-05 test]# dd if=/dev/zero of=testfile bs=1 count=1 conv=notrunc 
1+0 records in
1+0 records out
1 byte (1 B) copied, 5.1e-05 seconds, 19.6 kB/s
[root@bear-05 test]# hexdump -C testfile | more
00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000ba0  d0 be 95 0f 00 00 00 00  03 00 00 00 00 00 00 00  |................|
00000bb0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000c20  00 05 00 00 05 00 00 00  bf 00 00 00 3b 8a 00 00  |............;...|
00000c30  00 03 1c 7f 15 04 00 01  00 11 13 1a 00 12 0f 17  |................|
00000c40  16 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000c50  00 00 00 00 0f 00 00 00  0f 00 00 00 00 00 00 00  |................|
00000c60  00 00 00 00 00 00 00 00  70 d9 95 0f 00 00 00 00  |........p.......|
00000c70  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000cd0  30 e5 95 0f 00 00 00 00  80 63 95 0f 00 00 00 00  |0........c......|
00000ce0  01 00 00 00 00 00 00 00  33 89 11 4a 00 00 00 00  |........3..J....|
00000cf0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000d00  00 00 00 00 00 00 00 00  04 00 00 00 04 00 00 00  |................|
00000d10  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|

This should be all zeros.

Thanks,
-Eric

Comment 5 Don Zickus 2009-05-21 15:37:11 UTC

in kernel-2.6.18-150.el5
You can download this test kernel from http://people.redhat.com/dzickus/el5

Please do NOT transition this bugzilla state to VERIFIED until our QE team
has sent specific instructions indicating when to do so.  However feel free
to provide a comment indicating that this fix has been verified.

Comment 10 Eric Sandeen 2009-08-12 15:38:51 UTC

The falloc.c you sent should work fine in "syscall" mode (sorry, I missed the NEEDINFO on this somehow)... (and sorry, I should have attached mine in the first place)

I'd suggest trying again with 4k blocks at mkfs time, rather than 1k (mkfs.ext4 -b 4096....)

-Eric

Comment 11 errata-xmlrpc 2009-09-02 08:45:09 UTC

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 therefore 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-2009-1243.html