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Date:      Fri, 9 May 2014 13:22:20 -0700
From:      javocado <javocado@gmail.com>
To:        FreeBSD Filesystems <freebsd-fs@freebsd.org>
Subject:   Data loss in ZFS filesystem: directory disappears after extattr issues
Message-ID:  <CAP1HOmRkDMKre4ReRDL%2BZvA4OYsi%2Bub5t_U=QL3n71u4wtcpSg@mail.gmail.com>

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OS: freebsd 8.3-RELEASE

I am seeing an issue where a directory in a ZFS filesystem has just
disappeared.

When I do an 'ls' in that filesystem, I get:

# ls
ls: backup: No such file or directory
regular_file1
regular_file2
regular_file3
#


... so the OS knows it is there, but then it can't show it. Note that I was
running just a plain old 'ls' command, so if it really wasn't there, it
would just show nothing.

Also, I can autocomplete the "backup" directory from the shell ... so
somehow it sees it there, but won't do anything with it.

This behavior also appears in the snapshots I am making. Unfortunately I
did not notice this before several older snapshots had been destroyed. So
I'll never know whether the snapshots (rotated daily) taken before this
directory became inaccessible were also affected.

I have tried the following, but nothing has fixed the issue:

- rebooting
- scrub'ing the pool
- zfs send | receive to a new filesystem

The only interesting thing about this filesystem, and this directory, is
that it
contains a lot of files with extended attributes.

Further, these extattrs were crashing the system regularly until we applied
a patch from Pawel:

http://pastebin.com/0mu50B7T

... now the crashing has stopped, but that directory has ... disappeared.
This directory that is now gone is absolutely the directory whose contents
were causing the crashes.

We have a lot of questions about this, but maybe we can start with:  What
in the world is going on here ?

Thanks.



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