GFS2: Test bufdata with buffer locked and gfs2_log_lock held
authorBenjamin Marzinski <bmarzins@redhat.com>
Wed, 7 Nov 2012 06:38:06 +0000 (00:38 -0600)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 17 Nov 2012 21:19:06 +0000 (13:19 -0800)
commitf4c27fc8bffdb18f1e78c6cd25264a0880b39010
treeaa88e9e1539bceb871777b5e196b3cefb4343cdb
parent9a7c2012cafea0ee0c507b411f33d279a115d623
GFS2: Test bufdata with buffer locked and gfs2_log_lock held

commit 96e5d1d3adf56f1c7eeb07258f6a1a0a7ae9c489 upstream.

In gfs2_trans_add_bh(), gfs2 was testing if a there was a bd attached to the
buffer without having the gfs2_log_lock held. It was then assuming it would
stay attached for the rest of the function. However, without either the log
lock being held of the buffer locked, __gfs2_ail_flush() could detach bd at any
time.  This patch moves the locking before the test.  If there isn't a bd
already attached, gfs2 can safely allocate one and attach it before locking.
There is no way that the newly allocated bd could be on the ail list,
and thus no way for __gfs2_ail_flush() to detach it.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs/gfs2/lops.c
fs/gfs2/trans.c