Bug 194913

Summary:	Problem with mount_nullfs
Product:	Base System	Reporter:	darkdays <dawid.piotrowski>
Component:	bin	Assignee:	freebsd-bugs (Nobody) <bugs>
Status:	Closed Unable to Reproduce
Severity:	Affects Some People	CC:	ian
Priority:	---
Version:	10.0-RELEASE
Hardware:	amd64
OS:	Any

Description darkdays 2014-11-09 18:41:11 UTC

I discoverd an issue with mount_nullfs binary. When phisical drive eg. /dev/da0p2 is mounted to / and i mount_nullfs eg. /home/user /mnt (or any other place), there is a problem with updating space in df -h. What i know, when i do dd if=/dev/zero of=bigfile bs=1024 count=5120000 in /mnt and do df -h i get properly announced space (-500mb of free space), but when i deleted bigfile in /mnt that 500MB wont back to Avail neither on nullfs mount or in phisical drive mount. What helps is unmounting nullfs and then space info get updated on phisical drive mount. 
I did a tests on 2 diferent machines, both with latest stable FreeBSD. If needed i can provide additional info.

Comment 1 darkdays 2014-11-13 12:35:24 UTC

StepByStep to reproduce this bug

mount_nullfs /home/<user>/ /mnt/
df -h
cd /mnt/
dd if=/dev/zero of=bigfile bs=1024 count=1024000
df -h
rm bigfile

compare if 500mb of space get back to Avail