Date: Tue, 19 Sep 2017 16:58:30 +0200 From: Andreas Longwitz <longwitz@incore.de> To: Konstantin Belousov <kostikbel@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: nullfs with double mount is broken in FreeBSD 10 Stable Message-ID: <59C13096.9070402@incore.de> In-Reply-To: <20170919095447.GZ78693@kib.kiev.ua> References: <59C0E45E.3070603@incore.de> <20170919095447.GZ78693@kib.kiev.ua>
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Thanks for quick answer ! Konstantin Belousov wrote: > On Tue, Sep 19, 2017 at 11:33:18AM +0200, Andreas Longwitz wrote: >> The described problem does not exist in V8, but in V10 Stable r317936. >> >> I use a device /dev/md2 defined in /etc/rc.conf: >> >> mdconfig_md2="-t swap -s 384m" >> mdconfig_md2_newfs="-n" >> mdconfig_md2_owner="root:wheel" >> mdconfig_md2_perms="750" >> >> In /etc/fstab I have: >> >> /dev/md2 /tmp1 ufs rw,async,noatime,noauto 0 0 >> /tmp1 /home/tmp1 nullfs rw,noauto 0 0 >> /tmp1 /var/tmp1 nullfs rw,noauto 0 0 >> >> Now I run: >> >> mount /home/tmp1 >> mount /var/tmp1 >> while true; do >> rm -f /home/tmp1/* >> cpdup /boot/kernel /home/tmp1 >> cp /var/tmp1/kernel /dev/null >> df -h /tmp1 >> done >> >> The output is >> >> Filesystem Size Used Avail Capacity Mounted on >> /dev/md2 372M 88M 254M 26% /tmp1 >> Filesystem Size Used Avail Capacity Mounted on >> /dev/md2 372M 100M 242M 29% /tmp1 >> Filesystem Size Used Avail Capacity Mounted on >> /dev/md2 372M 112M 229M 33% /tmp1 >> Filesystem Size Used Avail Capacity Mounted on >> /dev/md2 372M 125M 217M 36% /tmp1 >> ..... >> >> The "Used" space grows quickly until "No space available". >> After umount /var/tmp1 the space is back again. >> >> I see the same behaviour when md is replaced by tmpfs. >> >> I have tried the patch from commit 317936 (V11) without success. >> The problem exists on i386 and amd64. In production (V8) I use this >> double mount construction for jail communication without any problems. > > Can you try the _latest_ stable/11 ? It is enough to only install the > kernel, keep the userspace. > > If it does not help, perhaps you will need the -o nocache mount option. Yes, the option -o nocache worked for me. Please can you tell me whether the commit 305659 (nullfs: plug vnode ref leak in null_vptocnp) should be used in stable/10 (in stable/11 it is commit 306682) ? -- Andreas Longwitz
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