raid5-cache: fix a deadlock in superblock write

There is a potential deadlock in superblock write. Discard could zero data, so
before discard we must make sure superblock is updated to new log tail.
Updating superblock (either directly call md_update_sb() or depend on md
thread) must hold reconfig mutex. On the other hand, raid5_quiesce is called
with reconfig_mutex hold. The first step of raid5_quiesce() is waitting for all
IO finish, hence waitting for reclaim thread, while reclaim thread is calling
this function and waitting for reconfig mutex. So there is a deadlock. We
workaround this issue with a trylock. The downside of the solution is we could
miss discard if we can't take reconfig mutex. But this should happen rarely
(mainly in raid array stop), so miss discard shouldn't be a big problem.

Cc: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

path: root/flowtop.zsh

#compdef flowtop
#
# flowtop.zsh -- zsh completion function for flowtop
#
# Copyright (C) 2013 Hideo Hattori <hhatto.jp@gmail.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.

typeset -A opt_args

_arguments -s -S \
    "(-4 --ipv4)"{-4,--ipv4}"[Show only IPv4 flows (default)]" \
    "(-6 --ipv6)"{-6,--ipv6}"[Show only IPv6 flows (default)]" \
    "(-T --tcp)"{-T,--tcp}"[Show only TCP flows (default)]" \
    "(-U --udp)"{-U,--udp}"[Show only UDP flows]" \
    "(-D --dccp)"{-D,--dccp}"[Show only DCCP flows]" \
    "(-I --icmp)"{-I,--icmp}"[Show only ICMP/ICMPv6 flows]" \
    "(-S --sctp)"{-S,--sctp}"[Show only SCTP flows]" \
    "(-s --show-src)"{-s,--show-src}"[Also show source, not only dest]" \
    "(-u --update)"{-u,--update}"[Update GeoIP databases]" \
    {-v,--version}"[Print version and exit]:" \
    {-h,--help}"[Print help and exit]:" \
    "*::args:_gnu_generic"