Race condition in free space check

[Michael Vogt]

Binary package hint: update-manager

With this filesystem layout:

Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda6 4996728 4195184 547720 89% /
varrun 257736 120 257616 1% /var/run
varlock 257736 4 257732 1% /var/lock
procbususb 10240 144 10096 2% /proc/bus/usb
udev 10240 144 10096 2% /dev
devshm 257736 0 257736 0% /dev/shm
lrm 257736 18132 239604 8%
+/lib/modules/2.6.17-11-386/volatile
/dev/hda5 17927776 7373344 10554432 42% /data
tmpfs 257736 27880 229856 11% /lib/modules/2.6.20-13-generic/volatile
tmpfs 257736 28604 229132 12% /lib/modules/2.6.20-13-386/volatile

the release upgrader detects:
2007-03-26 11:36:56,719 DEBUG Free space on /: 1074782208
2007-03-26 11:36:56,719 DEBUG Dir /usr mounted on /
2007-03-26 11:36:56,719 DEBUG Dir /var mounted on /
2007-03-26 11:36:56,719 DEBUG Free space on /boot: 1074778112
2007-03-26 11:36:56,720 DEBUG Dir /var/cache/apt/archives/ mounted on /boot
2007-03-26 11:36:56,720 DEBUG Dir /home mounted on /boot

This is clearly a race condition in the statvfs call.