From ce23bba842aee98092225d9576dba47c82352521 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Wed, 27 Feb 2013 17:03:56 -0800
Subject: [PATCH] block: fix synchronization and limit check in
 blk_alloc_devt()

idr allocation in blk_alloc_devt() wasn't synchronized against lookup
and removal, and its limit check was off by one - 1 << MINORBITS is
the number of minors allowed, not the maximum allowed minor.

Add locking and rename MAX_EXT_DEVT to NR_EXT_DEVT and fix limit
checking.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
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