git: dm - get rid of excessive locking and redundancy

[Alex Hornung <alexh@xxxxxxxxxxxxxxxxxxxxxxx>]

commit ba65987cf1e7af06cfd4295d0bd5e67e3469e4a2
Author: Alex Hornung <ahornung@gmail.com>
Date:   Thu Jul 14 19:43:15 2011 +0100

    dm - get rid of excessive locking and redundancy
    
     * Just use dev->si_drv1 for the strategy, disk ioctl and dump as the
       underlying device and 'dmv' is guaranteed not to go away. Keep the
       locked approach (dm_dev_lookup) for open, close, and mapper ioctls to
       ensure that we never rip out any node that's still in use.
    
     * This eliminates exclusive locking in the IO path, which should
       improve performance.

Summary of changes:
 sys/dev/disk/dm/device-mapper.c |   25 +++++--------------------
 sys/dev/disk/dm/dm_dev.c        |    3 +++
 sys/dev/disk/dm/dm_ioctl.c      |    6 ++++--
 3 files changed, 12 insertions(+), 22 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/ba65987cf1e7af06cfd4295d0bd5e67e3469e4a2


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