[3.16.y-ckt stable] Patch "dm cache: fix missing ERR_PTR returns and handling" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    dm cache: fix missing ERR_PTR returns and handling

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt6.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 2d9af2b8acc3155ecde5ad6dff1fa540f37e3e8a Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt at redhat.com>
Date: Wed, 28 Jan 2015 12:07:46 +0000
Subject: dm cache: fix missing ERR_PTR returns and handling

commit 766a78882ddf79b162243649d7dfdbac1fb6fb88 upstream.

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 at oracle.com>
Signed-off-by: Joe Thornber <ejt at redhat.com>
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/md/dm-cache-metadata.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index bf854ae27240..01ad0c2c0229 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;
--
2.1.4