commit d863b50ab01333659314c2034890cb76d9fdc3c7
author Boaz Harrosh <bharrosh@panasas.com> Thu Feb 10 15:01:20 2011 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> Fri Feb 11 16:12:19 2011 -0800
tree 88d27ed4717bb49ba696f2efb5ef024388412af3
parent 2dab597441667d6c04451a7dcf215241ad4c74f6

vfs: call rcu_barrier after ->kill_sb()

In commit fa0d7e3de6d6 ("fs: icache RCU free inodes"), we use rcu free
inode instead of freeing the inode directly.  It causes a crash when we
rmmod immediately after we umount the volume[1].

So we need to call rcu_barrier after we kill_sb so that the inode is
freed before we do rmmod.  The idea is inspired by Aneesh Kumar.
rcu_barrier will wait for all callbacks to end before preceding.  The
original patch was done by Tao Ma, but synchronize_rcu() is not enough
here.

1. http://marc.info/?l=linux-fsdevel&m=129680863330185&w=2

Tested-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>