dm thin: don't allow messages to be sent to a pool target in READ_ONLY or FAIL mode

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>
Cc: stable@vger.kernel.org

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 493478989dbd..07705ee181e3 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -3385,6 +3385,12 @@ static int pool_message(struct dm_target *ti, unsigned argc, char **argv)
         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);