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)
committerSteven Whitehouse <swhiteho@redhat.com>
Wed, 7 Nov 2012 09:43:03 +0000 (09:43 +0000)
commit96e5d1d3adf56f1c7eeb07258f6a1a0a7ae9c489
treeca5a7f4cf7508bc287af7b35b1d75e71d11f765b
parent3d1626889a64bd5a661544d582036a0a02104a60
GFS2: Test bufdata with buffer locked and gfs2_log_lock held

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>
fs/gfs2/lops.c
fs/gfs2/trans.c