[PATCH 3.18 36/57] dm thin: dont allow messages to be sent to a pool target in READ_ONLY or FAIL mode

Greg Kroah-Hartman
2015-02-03T23:46:53Z

From: Joe Thornber <ejt@redhat.com>

commit 2a7eaea02b99b6e267b1e89c79acc6e9a51cee3b upstream.

You can't modify the metadata in these modes. It's better to fail these
messages immediately than let the block-manager deny write locks on
metadata blocks. Otherwise these failed metadata changes will trigger
'needs_check' to get set in the metadata superblock -- requiring repair
using the thin_check utility.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/dm-thin.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2978,6 +2978,12 @@ static int pool_message(struct dm_target
struct pool_c *pt = ti->private;
struct pool *pool = pt->pool;

+ if (get_pool_mode(pool) >= PM_READ_ONLY) {
+ DMERR("%s: unable to service pool target messages in READ_ONLY or FAIL mode",
+ dm_device_name(pool->pool_md));
+ return -EINVAL;
+ }
+
if (!strcasecmp(argv[0], "create_thin"))
r = process_create_thin_mesg(argc, argv, pool);