From: Yi Yang <yi.y.yang@intel.com>

Live image with 2.6.30 kernel created by livecd-tools can't boot because
of device mapper driver regression, error info is below:

device-mapper: snapshot exception stores: Module for exstore type "p" not found

commit f6bd4eb73cdf2a5bf954e497972842f39cabb7e3 ("dm exception store: fix
exstore lookup to be case insensitive") claimed it fixed a regression, but
actually it introduced another error, 'p' in the above error message will
become 'P' followed by many strange characters.

The root cause is the variable persistent is of type char but it is used
as char *, so commit f6bd4eb73cdf2a5bf954e497972842f39cabb7e3 didn't fix
the issue and introduced one more issue.

Signed-off-by: Yi Yang <yi.y.yang@intel.com>
Cc: Jonathan Brassow <jbrassow@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff -puN drivers/md/dm-exception-store.c~dm-fix-exstore-lookup-error drivers/md/dm-exception-store.c
--- a/drivers/md/dm-exception-store.c~dm-fix-exstore-lookup-error
+++ a/drivers/md/dm-exception-store.c
@@ -197,7 +197,7 @@ int dm_exception_store_create(struct dm_
 	int r = 0;
 	struct dm_exception_store_type *type;
 	struct dm_exception_store *tmp_store;
-	char persistent;
+	char persistent[2];
 
 	if (argc < 3) {
 		ti->error = "Insufficient exception store arguments";
@@ -210,13 +210,14 @@ int dm_exception_store_create(struct dm_
 		return -ENOMEM;
 	}
 
-	persistent = toupper(*argv[1]);
-	if (persistent != 'P' && persistent != 'N') {
+	persistent[0] = toupper(*argv[1]);
+	if (persistent[0] != 'P' && persistent[0] != 'N') {
 		ti->error = "Persistent flag is not P or N";
 		return -EINVAL;
 	}
 
-	type = get_type(&persistent);
+	persistent[1] = '\0';
+	type = get_type(persistent);
 	if (!type) {
 		ti->error = "Exception store type not recognised";
 		r = -EINVAL;
_