Date: Fri, 17 Jun 2011 17:34:15 +0200 From: Hans Ottevanger <hans@beastielabs.net> To: freebsd-current@freebsd.org Subject: SU+J: negative used diskspace (for a while) Message-ID: <20110617153415.GA92803@testsoekris.hotsoft.nl>
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Hi, I found a possible issue with SU+J on recent versions of -CURRENT. After deleting a large file hierarchy (copy of /usr/src, ~1.5 Gbyte), df reports a negative number of blocks "Used" for a while. I am using a GENERIC kernel (r223184) on an amd64 platform. The hardware is relatively simple: Intel DP965LT mainboard with a Q6600 CPU, 8 Gbyte RAM and two Samsung 501LJ 500 Gbyte SATA disks. The issue can be demonstrated by copying /usr/src to the current directory (cp -R /usr/src .) and running the following script to delete the copy and print the free space at 10 second intervals: #!/bin/sh df . time rm -rf src echo 'src is gone ...' while true do df . | tail -1 sleep 10 done This yields the following output: Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/ada0s1g 416144900 1612066 381241242 0% /home 51.21 real 1.00 user 17.38 sys src is gone ... /dev/ada0s1g 416144900 -164692 383018000 -0% /home /dev/ada0s1g 416144900 -165082 383018390 -0% /home /dev/ada0s1g 416144900 -246852 383100160 -0% /home /dev/ada0s1g 416144900 -246852 383100160 -0% /home /dev/ada0s1g 416144900 -246852 383100160 -0% /home /dev/ada0s1g 416144900 -64146 382917454 -0% /home /dev/ada0s1g 416144900 -64146 382917454 -0% /home /dev/ada0s1g 416144900 -64146 382917454 -0% /home /dev/ada0s1g 416144900 32910 382820398 0% /home /dev/ada0s1g 416144900 32910 382820398 0% /home So it takes more than a minute before the disk space is back to "normal" values. After disabling journaling (tunefs -j disable) I get the following output: Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/ada0s1g 416144900 1579284 381274024 0% /home 35.40 real 0.96 user 13.32 sys src is gone ... /dev/ada0s1g 416144900 128 382853180 0% /home /dev/ada0s1g 416144900 128 382853180 0% /home /dev/ada0s1g 416144900 128 382853180 0% /home /dev/ada0s1g 416144900 128 382853180 0% /home which is as it should be. The problem also does not occur with journaling enabled when I revert to r222723. Is anybody else seeing these weird phenomena? Could this be related to the recent changes to UFS? Kind regards, Hans Ottevanger
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