Testing revealed long pauses of the entire system while autofs initiated
umounts as a result of timing out the mounts.

It was noticed that during a umount, the BKL is held while scanning the
inode_list and removing and inodes that are candidates.  This patch moves
locking until after the first pass had gone through the inode_list.

Testing revelead that on an ia64 machine with a filesystem that had 8.4
Million inodes, there were no observable pauses during the umount.  This
was down from over 4 seconds without this patch.
Signed-Off-By: Robin Holt <holt@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>