Date: Fri, 12 Nov 2010 14:57:58 +0300 From: "Alexander Zagrebin" <alexz@visp.ru> To: <freebsd-stable@freebsd.org>, <freebsd-fs@freebsd.org> Subject: 8.1-STABLE: problem with unmounting ZFS snapshots Message-ID: <D9ABDE54892A4D9285FE7FFA6E1B1B69@vosz.local>
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I have found that there is an issue with unmounting ZFS snapshots: the /sbin/umount "hangs" after unmounting. The test system is i386, but I can reproduce this issue on amd64 too. # uname -a FreeBSD alpha.vosz.local 8.1-STABLE FreeBSD 8.1-STABLE #0: Tue Oct 19 18:47:05 MSD 2010 root@alpha.vosz.local:/usr/obj/usr/src/sys/GENERIC i386 How to try to repeat: # zfs snapshot pool/var@test # zfs list -t all -r pool/var NAME USED AVAIL REFER MOUNTPOINT pool/var 4,86M 2,99G 4,86M /var pool/var@test 0 - 4,86M - # mount -t zfs pool/var@test /mnt # mount ... pool/var@test on /mnt (zfs, local, noatime, read-only) # umount /mnt At this point umount hangs and it's impossible to kill it even with the `kill -9`. >From the working console I can see that: 1. snapshot is unmounted successfully # mount pool/root on / (zfs, local) devfs on /dev (devfs, local, multilabel) pool/home on /home (zfs, local) pool/tmp on /tmp (zfs, local) pool/usr on /usr (zfs, local) pool/usr/src on /usr/src (zfs, local) pool/var on /var (zfs, local) 2. the umount is waiting for disk #ps | egrep 'PID|umount' PID TT STAT TIME COMMAND 958 0 D+ 0:00,04 umount /mnt # procstat -t 958 PID TID COMM TDNAME CPU PRI STATE WCHAN 958 100731 umount - 3 133 sleep mntref Can anybody confirm this issue? Any suggestions? -- Alexander Zagrebin
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