Date: Mon, 14 Aug 2017 14:07:44 +0200 From: tsuroerusu@gmail.com To: freebsd-stable@freebsd.org Subject: Re: nullfs making contents of ZFS datasets invisible even after unmounting Message-ID: <CALrBqsE3%2BaOYeYZZLbqY0J=4%2BdOF5MQF3PykJnbybEMM_BkS9Q@mail.gmail.com> In-Reply-To: <CALrBqsHBeNYks9yxP8mMtS%2BwymCoDzq4ZXgEeAheJEdHtGCjQw@mail.gmail.com> References: <CALrBqsHBeNYks9yxP8mMtS%2BwymCoDzq4ZXgEeAheJEdHtGCjQw@mail.gmail.com>
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With a little bit of help, I managed to figure out what the problem was. It turned out that I had run, head first, into the wall of nullfs not operating across file systems. Thus inside the jail, the data was being saved to a regular directory on my "storage/cloud"-dataset (Mountpoint: /storage/cloud), whereas outside the jail the child file system "storage/cloud/bc", having been left empty, was mounted over the folder "bc" on "storage/cloud", where the files actually resided, thus "hiding" them from view outside the jail. A simple "zfs unmount storage/cloud/bc" revealed them. Anybody reading this in the future: If you are using ZFS and want to put a file system and all of its children into a jail then you cannot use nullfs. Instead you need to either change the actual mount point using "zfs set mountpoint=/jails/jail1/storage storage/path/to/filesystem" or to attach the entire dataset to the jail, and allow it to be managed from within the jail using "zfs jail". 2017-08-14 10:34 GMT+02:00 <tsuroerusu@gmail.com>: > I am running a FreeBSD 11.1 system with ZFS and jails and I mount a > file system on my storage pool (/storage/cloud) into the jail > (/jails/cloud/storage) via nullfs, and that works fine for what the > jail does. However I just noticed that outside the jail, I can only > see the mount points of the file system children, but not the > contents. > > For example if I do: ls -la /storage/cloud/* (As root) then nothing > shows up, but they are present inside the jail. Even if I stop the > jail, they still are not present outside the jail. > > I just tried disabling jails in /etc/rc.conf and rebooting the system > and EVEN THEN the files do not reappear outside the jail in their > original location, yet zfs list reports the space being used. But if I > then (without rebooting) enable the jail, the files show up in the > nullfs-mounted location inside the jail! > > As an experiment, I tried creating /mnt/test and /mnt/test2 and > creates a folder and a few files in test, and then nullfs-mounted it > onto test2, and I could then see the files in both locations. > > Does anybody know what might be causing this? The fact that my data > stays hidden after a reboot is rather worrisome.
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