dm cache: fix missing ERR_PTR returns and handling

Commit 9b1cc9f251 ("dm cache: share cache-metadata object across
inactive and active DM tables") mistakenly ignored the use of ERR_PTR
returns.  Restore missing IS_ERR checks and ERR_PTR returns where
appropriate.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 21b156242e42..c1c010498a21 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -683,7 +683,7 @@ static struct dm_cache_metadata *metadata_open(struct block_device *bdev,
         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
         if (!cmd) {
                 DMERR("could not allocate metadata struct");
-                return NULL;
+                return ERR_PTR(-ENOMEM);
         }
 
         atomic_set(&cmd->ref_count, 1);
@@ -745,7 +745,7 @@ static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev,
                 return cmd;
 
         cmd = metadata_open(bdev, data_block_size, may_format_device, policy_hint_size);
-        if (cmd) {
+        if (!IS_ERR(cmd)) {
                 mutex_lock(&table_lock);
                 cmd2 = lookup(bdev);
                 if (cmd2) {
@@ -780,9 +780,10 @@ struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
 {
         struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size,
                                                        may_format_device, policy_hint_size);
-        if (cmd && !same_params(cmd, data_block_size)) {
+
+        if (!IS_ERR(cmd) && !same_params(cmd, data_block_size)) {
                 dm_cache_metadata_close(cmd);
-                return NULL;
+                return ERR_PTR(-EINVAL);
         }
 
         return cmd;