linux-kernel - [PATCH] dm: writecache: fix format string warning

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Message-Id: <20180528155432.2864616-1-arnd@arndb.de>
Date:   Mon, 28 May 2018 17:54:08 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com
Cc:     Arnd Bergmann <arnd@...db.de>,
        Mikulas Patocka <mpatocka@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] dm: writecache: fix format string warning

The return type of ACCESS_ONCE is configuration dependent and may be either
'int' or 'long int' for the writecache_has_error() macro, so we get a warning
like this for either format string:

In file included from drivers/md/dm-writecache.c:8:
drivers/md/dm-writecache.c: In function 'writecache_status':
drivers/md/dm-writecache.c:2227:10: error: format '%ld' expects argument of type 'long int', but argument 4 has type 'int' [-Werror=format=]
   DMEMIT("%ld %llu %llu %llu", writecache_has_error(wc),
          ^~~~~~~~~~~~~~~~~~~~
include/linux/device-mapper.h:549:46: note: in definition of macro 'DMEMIT'
      0 : scnprintf(result + sz, maxlen - sz, x))
                                              ^

The code is otherwise correct, so we just need to shut up the warning,
which can be done using an extra type cast.

Fixes: bb15b431d650 ("dm: add writecache target")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/md/dm-writecache.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index 1ef06e738eb6..772ac3a57287 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -2224,7 +2224,7 @@ static void writecache_status(struct dm_target *ti, status_type_t type,
 
 	switch (type) {
 	case STATUSTYPE_INFO:
-		DMEMIT("%ld %llu %llu %llu", writecache_has_error(wc),
+		DMEMIT("%ld %llu %llu %llu", (long)writecache_has_error(wc),
 		       (unsigned long long)wc->n_blocks, (unsigned long long)wc->freelist_size,
 		       (unsigned long long)wc->writeback_size);
 		break;
-- 
2.9.0