fs,btrfs: fix rt deadlock on extent_buffer->lock
Sat Jul 14 12:30:41 CEST 2012
Trivially repeatable deadlock is cured by enabling lockdep code in
btrfs_clear_path_blocking() as suggested by Chris Mason. He also
suggested restricting blocking reader count to one, and not allowing
a spinning reader while blocking reader exists. This has proven to
be unnecessary, the strict lock order enforcement is enough.. or
rather that's my box's opinion after long hours of hard pounding.
Note: extent-tree.c bit is additional recommendation from Chris
Mason, split into a separate patch after discussion.
Link: http://lkml.kernel.org/r/1414913478.5380.114.camel@marge.simpson.net
Cc: linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Carsten Emde <C.Emde@osadl.org>
Cc: John Kacur <jkacur@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Clark Williams <williams@redhat.com>
Cc: Chris Mason <chris.mason@fusionio.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2 files changed