kern/184677

[krichy at tvnetwork.hu]

Dear devs,

I've attached a patch, which makes the recursive lockmgr disappear, and 
makes the reported bug to disappear. I dont know if I followed any 
guidelines well, or not, but at least it works for me. Please some 
ZFS/FreeBSD fs expert review it, and fix it where it needed.

But unfortunately, my original problem is still not solved, maybe the same 
as Ryan's: 
http://lists.freebsd.org/pipermail/freebsd-fs/2013-December/018707.html

Tracing the problem down is that zfsctl_snapdir_lookup() tries to acquire 
spa_namespace_lock while when finishing a zfs send -R does a 
zfsdev_close(), and that also holds the same mutex. And this causes a 
deadlock scenario. I looked at illumos's code, and for some reason they 
use another mutex on zfsdev_close(), which therefore may not deadlock with 
zfsctl_snapdir_lookup(). But I am still investigating the problem.

I would like to help making ZFS more stable on freebsd also with its whole 
functionality. I would be very thankful if some expert would give some 
advice, how to solve these bugs. PJD, Steven, Xin?

Thanks in advance,


Kojedzinszky Richard
Euronet Magyarorszag Informatikai Zrt.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 184677.patch
Type: text/x-diff
Size: 5998 bytes
Desc: 
URL: <http://lists.freebsd.org/pipermail/freebsd-fs/attachments/20131216/8a1f37d4/attachment.patch>