Date: Sun, 25 Oct 2015 12:49:49 +0100 From: Niklaas Baudet von Gersdorff <niklaas@kulturflatrate.net> To: Matthew Seaman <matthew@FreeBSD.org>, freebsd-questions@freebsd.org Subject: Re: cd /.zfs/snapshot hangs (tmux put to uninterruptible sleep) Message-ID: <562CC1DD.9060207@kulturflatrate.net> In-Reply-To: <562CB8CF.7010504@FreeBSD.org> References: <562CB2C2.6090402@kulturflatrate.net> <562CB8CF.7010504@FreeBSD.org>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 25/10/15 12:11, Matthew Seaman wrote: > On 25/10/2015 10:45, Niklaas Baudet von Gersdorff wrote: >> Why am I not able to see the output of `cd /.zfs/snapshot`? Did I >> reach the limit of possible snapshots? > > I don't think it's the number of snapshots that's causing the > problem, but that you've tried to create a snapshot that breaks a > limit on the path length of a mount point. See for instance: > > https://lists.freebsd.org/pipermail/freebsd-fs/2010-March/007964.html > > Even though that report is five years old, the same limits still > apply today. Thanks for the link. Yeah, that might be. Do I understand correctly (from the link above) that the maximal length of a name is 88? See: > /* * filesystem statistics */ [...] #define MNAMELEN 88 > /* size of on/from name bufs */ [...] struct statfs { [...] char > f_mntfromname[MNAMELEN];/* mounted filesystem */ char > f_mntonname[MNAMELEN]; /* directory on which mounted */ }; Isn't this a bug? Shouldn't the request just fail instead of putting the process into D? > When you run into the limit, it is not that the snapshot automount > simply fails: it leaves the system in a less than ideal state, and > you have to force unmount the path where the the snapshot would > have been mounted. > > umount -f /.zfs/snapshot/some-directory Unfortunately, `mount` doesn't reveal any mounts in /.zfs . > Unfortunately when a process gets into state 'D' there doesn't seem > to be anything that can be done, short of rebooting the machine, to > get rid of it. If anyone knows any different I'd be glad to hear > of it. Uff. Because I do snapshotting regularly with a script in cron I've got now several processes in D. Even zfskern. Probably I should restart the machine... > $ sudo ps ax | grep zfs 3 - DL 24:03.30 [zfskern] 84869 - > D 0:00.00 ls /.zfs/snapshot/ 84873 - D 0:00.00 ls > /.zfs/snapshot/ 85382 - D 0:00.00 ls /.zfs/snapshot/ > 86137 - D 0:00.00 ls /.zfs/snapshot/ 86708 - D > 0:00.00 ls /.zfs/snapshot/ 87391 - D 0:00.00 ls > /.zfs/snapshot/ 87396 - D 0:00.00 ls /.zfs/snapshot/ > 89474 - D 0:00.00 ls /.zfs/snapshot/ 84979 17- D+ > 0:00.00 ls -ls /.zfs/snapshot 90618 24 S+ 0:00.00 grep zfs - -- Niklaas -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJWLMHTAAoJEG2fODeJrIU/ZdYP/1rA7Ot7b5PbuYfuD92Nylkv WPebYkgNwd7l/mBQ4ERHTczYslp3LNFF/0PLD3akjgN98Qi4AzTeYam0P5OOL0Km mkvIS3pIhsdBjtGCQEoZrBefqQzscRsaKBjPCNVzy1Z/mH6+SFADNOBrv/B6JTlY ux3T8cJVdHroGmnUoIKkFHxfuxJLbex0JCmZEOTWqq+bw8Yv7wSSD+zj1ZN4k3Gh TFTFUaxUV+edaP8ZZbgmOspty7HMn4+w0F601c8kDrusHK1fTmByC3ymXM/S7WiV azcz+LdHCjeeaAwNSKgNntJicd8IxHEuw4TS9+HbqNHCsK8WABndrJ5tYa7hhNtG 1nkW4XQXBsFg9C7POOkSWjUOQ8hEOmPMyKFcs8FD4YlC9D2Vd9FPnsEHoXdWfUzb nUHmGVKFyZDvuTkA0CYTAzaOfxUXa1XIeQ/S3/dvGahJOOBMzJiu02CRPxSPEJ0t AcEgDoPcWSFfGrqUlq5M/qIzKi5r1HMBHk7E/6B3L7iAuOyHy0+tD6PbuEYPMU+k ibT0T04hub8TuuNqlGXAx+/uCP0CPLASj6MES5FLLBiBu+tGIcmCXJx/vULCWO07 mZM2VGNVNm4TZfrZO+5ioTnNkNyNe0UY2FLC0qmXeGgEFxdo9urJmZVSrDJ8bea3 Q1XcKc6bRLBxAVAjTRgm =eXiM -----END PGP SIGNATURE-----
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