Bug 14779

Summary: Disk space wastes a lot
Product: File System Reporter: zhipeng.gong (zhipeng.gong)
Component: btrfsAssignee: fs_btrfs (fs_btrfs)
Status: CLOSED OBSOLETE    
Severity: normal CC: alan, bugzilla.kernel.org, jukey, rdunlap
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 2.6.32.rc8 Subsystem:
Regression: No Bisected commit-id:

Description zhipeng.gong 2009-12-10 08:37:20 UTC 
Run dd to fill up the disk, the command will run until it hits "No space left
on device", however a lot of disk space are still not used. It is not
reasonable for netbook with small SSD or embedded devices with NAND.

Reproduce Steps
===========================================================
(1)"df -h" shows the free size is 12G
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              14G  2.0G   12G  15% /

(2)dd if=/dev/zero of=tmpfile bs=1024 count=$(the free size of the disk)
dd: writing `tmpfile': No space left on device
8836158+0 records in
8836157+0 records out
9048224768 bytes (9.0 GB) copied, 677.506 s, 13.4 MB/s

(3)and then "df -h" shows 23% are still available, but you can't write any
bytes any more.
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              14G   11G  3.3G  77% /
Comment 1 Rolf Leggewie 2012-01-19 07:04:26 UTC 
similar or probably the same issue are reported as

bug 16066
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/874684

I am experiencing the exact same issue in Ubuntu Lucid (Ubuntu Kernel and mainline kernel) as well as today's Debian Unstable.
Comment 2 Rolf Leggewie 2012-06-18 13:27:30 UTC 
How about you ask if this is fixed instead of silently closing as OBSOLETE?
Comment 3 Alan 2012-06-18 14:17:51 UTC 
How about because I couldn't make it break testing the example ?

Can you reproduce it ?
Comment 4 Rolf Leggewie 2012-06-18 14:36:28 UTC 
well, as you can see above I was able to reproduce it in January, less than half a year ago.  I'm no longer using btrfs since it's so horribly broken, but I can test it once when I return to civilzation.
Comment 5 Rolf Leggewie 2012-06-18 14:37:50 UTC 
bug 14779
bug 12555
bug 14113
bug 16066

(as taken from launchpad)