Bug 742201

Summary:	files written over an NFS share get padded with zeroes on PPC64
Product:	[Fedora] Fedora	Reporter:	Karsten Hopp <karsten>
Component:	kernel	Assignee:	Steve Dickson <steved>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	16	CC:	gansalmon, itamar, jlayton, jonathan, kernel-maint, madhu.chinakonda
Target Milestone:	---
Target Release:	---
Hardware:	powerpc
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-10-28 10:20:13 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:
Bug Depends On:
Bug Blocks:	718272

Description Karsten Hopp 2011-09-29 11:35:05 UTC

Description of problem:
I have 3 machines: 
- NFS server (Thecus N8800, but the same happens with a RHEL-4 server)
- F15 x86_64 machine with kernel 2.6.40.4-5.fc15.x86_64
- F16 PPC64 machine with kernel-3.1.0-0.rc6.git0.3.fc16.ppc64

on the x86_64 machine:
#> mount -o rw,rsize=4096,wsize=8192 nfs-server:/data/tmp /mnt/foo/
#> echo 1 > /mnt/foo/xxx; ls -l /mnt/foo/xxx
-rw-rw-rw- 1 karsten karsten 2 29. Sep 13:09 xxx

#> mount -o rw,rsize=4096,wsize=16384 nfs-server:/data/tmp /mnt/foo/
#> echo 1 > /mnt/foo/xxx; ls -l /mnt/foo/xxx
-rw-rw-rw- 1 karsten karsten 2 29. Sep 13:10 xxx

#> mount -o rw,rsize=4096,wsize=32738 nfs-server:/data/tmp /mnt/foo/
#> echo 1 > /mnt/foo/xxx; ls -l /mnt/foo/xxx
-rw-rw-rw- 1 karsten karsten 2 29. Sep 13:11 xxx

#> mount -o rw,rsize=4096,wsize=65536 nfs-server:/data/tmp /mnt/foo/
#> echo 1 > /mnt/foo/xxx; ls -l /mnt/foo/xxx
-rw-rw-rw- 1 karsten karsten 2 29. Sep 13:11 xxx




The same on the PPC64 machine:
#> mount -o rw,rsize=4096,wsize=8192 nfs-server:/data/tmp /mnt/foo/
#> echo 1 > /mnt/foo/xxx; ls -l /mnt/foo/xxx
-rw-rw-rw- 1 karsten karsten 8192 29. Sep 2011  xxx

#> mount -o rw,rsize=4096,wsize=16384 nfs-server:/data/tmp /mnt/foo/
#> echo 1 > /mnt/foo/xxx; ls -l /mnt/foo/xxx
-rw-rw-rw- 1 karsten karsten 16384 29. Sep 13:10 xxx

#> mount -o rw,rsize=4096,wsize=32768 nfs-server:/data/tmp /mnt/foo/
#> echo 1 > /mnt/foo/xxx; ls -l /mnt/foo/xxx
-rw-rw-rw- 1 karsten karsten 32768 29. Sep 2011  xxx


#> mount -o rw,rsize=4096,wsize=65535 nfs-server:/data/tmp /mnt/foo/
#> echo 1 > /mnt/foo/xxx; ls -l /mnt/foo/xxx
-rw-rw-rw- 1 karsten karsten 32768 29. Sep 2011  xxx

#> mount -o rw,rsize=4096,wsize=65536 nfs-server:/data/tmp /mnt/foo/
#> echo 1 > /mnt/foo/xxx; ls -l /mnt/foo/xxx
-rw-rw-rw- 1 karsten karsten 2 29. Sep 2011  xxx

#> mount | grep foo
nfs-server:/data/tmp/ on /mnt/foo type nfs (rw,relatime,vers=3,rsize=4096,wsize=32768,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=xx.xx.xx.xx,mountvers=3,mountport=903,mountproto=udp,local_lock=none,addr=xx.xx.xx.xx)

#> hexdump  xxx 
0000000 320a 0000 0000 0000 0000 0000 0000 0000
0000010 0000 0000 0000 0000 0000 0000 0000 0000
*
0008000


It's interesting that as long as wsize is greater than 65535, everything seems to be ok.

Comment 1 Josh Boyer 2011-09-29 11:52:29 UTC

Steve and Jay, any ideas?

Comment 2 Jeff Layton 2011-09-29 12:22:47 UTC

IIRC, ppc64 has 64k pages, right? It would be interesting to see if this commit helps:

commit f13c3620a4d1123dbf032f93f350b856ef292ced
Author: Trond Myklebust <Trond.Myklebust>
Date:   Mon Sep 12 11:47:53 2011 -0400

    NFS: Fix a typo in nfs_flush_multi
    
    Fix a typo which causes an Oops in the RPC layer, when using wsize < 4k.
    
    Signed-off-by: Trond Myklebust <Trond.Myklebust>
    Tested-by: Sricharan R <r.sricharan>

...currently the code does a wsize write even when there's less data to be written. nfs_flush_multi is only used when the wsize is less than the PAGE_CACHE_SIZE.

Comment 3 Josh Boyer 2011-09-29 13:39:44 UTC

(In reply to comment #2)
> IIRC, ppc64 has 64k pages, right? It would be interesting to see if this commit
> helps:

We recently switched Fedora to 64K pages, yes.  I don't remember exactly which NVR that happened in.

> commit f13c3620a4d1123dbf032f93f350b856ef292ced
> Author: Trond Myklebust <Trond.Myklebust>
> Date:   Mon Sep 12 11:47:53 2011 -0400
> 
>     NFS: Fix a typo in nfs_flush_multi

OK.  That is in rc7 I believe, so it should be easy enough to build and test.

(Aside, I suck for calling you Jay.  My apologies Jeff.)

Comment 4 IBM Bug Proxy 2011-10-27 16:20:22 UTC

------- Comment From baude.com 2011-10-27 12:09 EDT-------
reverse mirror bug

Comment 5 Karsten Hopp 2011-10-28 10:20:13 UTC

I've verified that this is fixed in 3.1.0-0.rc8.git0.0.fc16.kh.ppc64