[PATCH] dm transaction manager: handle space map checker failure

[Mike Snitzer <snitzer@xxxxxxxxxx>]

If CONFIG_DM_DEBUG_SPACE_MAPS is enabled and dm_sm_checker_create()
fails, dm_tm_create_internal() would still return success even though it
cleaned up all resources it was supposed to have created.

Fix the space map checker code to return an appropriate ERR_PTR and have
dm_tm_create_internal() check for it with IS_ERR.

Reported-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
 drivers/md/persistent-data/dm-space-map-checker.c  |   24 ++++++++++----------
 .../md/persistent-data/dm-transaction-manager.c    |    8 +++++-
 2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/drivers/md/persistent-data/dm-space-map-checker.c b/drivers/md/persistent-data/dm-space-map-checker.c
index 50ed53b..6d7c832 100644
--- a/drivers/md/persistent-data/dm-space-map-checker.c
+++ b/drivers/md/persistent-data/dm-space-map-checker.c
@@ -343,25 +343,25 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
 	int r;
 	struct sm_checker *smc;
 
-	if (!sm)
-		return NULL;
+	if (IS_ERR_OR_NULL(sm))
+		return ERR_PTR(-EINVAL);
 
 	smc = kmalloc(sizeof(*smc), GFP_KERNEL);
 	if (!smc)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	memcpy(&smc->sm, &ops_, sizeof(smc->sm));
 	r = ca_create(&smc->old_counts, sm);
 	if (r) {
 		kfree(smc);
-		return NULL;
+		return ERR_PTR(r);
 	}
 
 	r = ca_create(&smc->counts, sm);
 	if (r) {
 		ca_destroy(&smc->old_counts);
 		kfree(smc);
-		return NULL;
+		return ERR_PTR(r);
 	}
 
 	smc->real_sm = sm;
@@ -371,7 +371,7 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
 		ca_destroy(&smc->counts);
 		ca_destroy(&smc->old_counts);
 		kfree(smc);
-		return NULL;
+		return ERR_PTR(r);
 	}
 
 	r = ca_commit(&smc->old_counts, &smc->counts);
@@ -379,7 +379,7 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
 		ca_destroy(&smc->counts);
 		ca_destroy(&smc->old_counts);
 		kfree(smc);
-		return NULL;
+		return ERR_PTR(r);
 	}
 
 	return &smc->sm;
@@ -391,25 +391,25 @@ struct dm_space_map *dm_sm_checker_create_fresh(struct dm_space_map *sm)
 	int r;
 	struct sm_checker *smc;
 
-	if (!sm)
-		return NULL;
+	if (IS_ERR_OR_NULL(sm))
+		return ERR_PTR(-EINVAL);
 
 	smc = kmalloc(sizeof(*smc), GFP_KERNEL);
 	if (!smc)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	memcpy(&smc->sm, &ops_, sizeof(smc->sm));
 	r = ca_create(&smc->old_counts, sm);
 	if (r) {
 		kfree(smc);
-		return NULL;
+		return ERR_PTR(r);
 	}
 
 	r = ca_create(&smc->counts, sm);
 	if (r) {
 		ca_destroy(&smc->old_counts);
 		kfree(smc);
-		return NULL;
+		return ERR_PTR(r);
 	}
 
 	smc->real_sm = sm;
diff --git a/drivers/md/persistent-data/dm-transaction-manager.c b/drivers/md/persistent-data/dm-transaction-manager.c
index 02bf78e..e5604b3 100644
--- a/drivers/md/persistent-data/dm-transaction-manager.c
+++ b/drivers/md/persistent-data/dm-transaction-manager.c
@@ -347,8 +347,10 @@ static int dm_tm_create_internal(struct dm_block_manager *bm,
 		}
 
 		*sm = dm_sm_checker_create(inner);
-		if (!*sm)
+		if (IS_ERR(*sm)) {
+			r = PTR_ERR(*sm);
 			goto bad2;
+		}
 
 	} else {
 		r = dm_bm_write_lock(dm_tm_get_bm(*tm), sb_location,
@@ -367,8 +369,10 @@ static int dm_tm_create_internal(struct dm_block_manager *bm,
 		}
 
 		*sm = dm_sm_checker_create(inner);
-		if (!*sm)
+		if (IS_ERR(*sm)) {
+			r = PTR_ERR(*sm);
 			goto bad2;
+		}
 	}
 
 	return 0;
-- 
1.7.4.4

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