From 76df1c651b66bdf07d60b3d60789feb5f58d73e3 Mon Sep 17 00:00:00 2001
From: Alasdair G Kergon <agk@redhat.com>
Date: Mon, 27 Mar 2006 01:17:45 -0800
Subject: [PATCH] [PATCH] device-mapper snapshot: fix invalidation

When a snapshot becomes invalid, s->valid is set to 0.  In this state, a
snapshot can no longer be accessed.

When s->lock is acquired, before doing anything else, s->valid must be checked
to ensure the snapshot remains valid.

This patch eliminates some races (that may cause panics) by adding some
missing checks.  At the same time, some unnecessary levels of indentation are
removed and snapshot invalidation is moved into a single function that always
generates a device-mapper event.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
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