linux-ext4 - Re: ext4 fallocate+truncate not freeing up allocated space

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Date:	Fri, 29 Oct 2010 18:26:42 -0700
From:	George Kola <georgekola@...il.com>
To:	linux-ext4@...r.kernel.org
Subject: Re: ext4 fallocate+truncate not freeing up allocated space

Hi Erik,
      Thanks for replying. How to get a hold of kernel  2.6.18-225.el5
?  I found 2.6.18-227 at
http://people.redhat.com/jwilson/el5/227.el5/x86_64/
I tried it and the bug is fixed is 2.6.18-227.   Thanks for your help.
This may be off-topic -- how do I find the changes from
2.6.18-194.17.4 to 2.6.18-225 (or 2.6.18-227) ? I just want to know
what other changes I am installing in addition to the bug fix.

Thanks,
George

p/s: yes I am using FALLOC_FL_KEEP_SIZE.


On Fri, Oct 29, 2010 at 11:39 AM, Eric Sandeen <sandeen@...hat.com> wrote:
>
> George Kola wrote:
> > I am using RHEL (CentOS) 5.5 with kernel  2.6.18-194.17.4.el5  and ext4. I
> > posted to RHEL bugzilla and they requested me to post it here.
> >
>
> ...
>
> > Steps to Reproduce:
> >   Have a program
> > 1.  Open a file on ext4 partition
>
> # touch testfile
>
> > 2. Fallocate space for that file  say 20 GB
>
> # /root/fallocate -l 20g testfile
> # df -h .
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/sdb2              30G   21G  7.7G  73% /mnt/test
> # du -h testfile
> 21G     testfile
>
> > 3. Write data to the file  (but less than the allocated space) say 10 GB
>
> # dd if=/dev/zero of=testfile bs=10M count=1024 conv=notrunc
> 10737418240 bytes (11 GB) copied, 125.522 seconds, 85.5 MB/s
> # du -h testfile
> 21G     testfile
> # df -h .
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/sdb2              30G   21G  7.7G  73% /mnt/test
>
> > 4. Close the file
> > 5. Call truncate(file-path, size+1), truncate(file-path,size) on that file
> > to
> > give up the space (observed that the space is given up using filefrag)
>
> 10g size I assume? Is the below representative?
>
> # /root/truncate 10737418241 testfile
> # ls -l testfile
> -rw-r--r-- 1 root root 10737418241 Oct 29 13:48 testfile
> # /root/truncate 10737418240 testfile
> # ls -l testfile
> -rw-r--r-- 1 root root 10737418240 Oct 29 13:48 testfile
>
> > 6. Use du and df on that ext4 partition to find that the mismatch
>
> # df -h .
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/sdb2              30G   11G   18G  37% /mnt/test
>
> # du -h testfile
> 11G     testfile
>
> # uname -a
> Linux bear-05 2.6.18-225.el5 #1 SMP Mon Sep 27 10:32:19 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux
>
> Seems to work here, though there are ext4 updates in that kernel.
>
> -Eric
>
> >
> >
> > -George
> >
> >
> >
> > --
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