linux-kernel - [PATCH 4.4 014/103] dm cache metadata: fail operations if fail

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Date:   Tue, 23 May 2017 22:08:40 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mikulas Patocka <mpatocka@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>
Subject: [PATCH 4.4 014/103] dm cache metadata: fail operations if fail_io mode has been established

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mike Snitzer <snitzer@...hat.com>

commit 10add84e276432d9dd8044679a1028dd4084117e upstream.

Otherwise it is possible to trigger crashes due to the metadata being
inaccessible yet these methods don't safely account for that possibility
without these checks.

Reported-by: Mikulas Patocka <mpatocka@...hat.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/md/dm-cache-metadata.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -1326,17 +1326,19 @@ void dm_cache_metadata_set_stats(struct
 
 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown)
 {
-	int r;
+	int r = -EINVAL;
 	flags_mutator mutator = (clean_shutdown ? set_clean_shutdown :
 				 clear_clean_shutdown);
 
 	WRITE_LOCK(cmd);
+	if (cmd->fail_io)
+		goto out;
+
 	r = __commit_transaction(cmd, mutator);
 	if (r)
 		goto out;
 
 	r = __begin_transaction(cmd);
-
 out:
 	WRITE_UNLOCK(cmd);
 	return r;
@@ -1348,7 +1350,8 @@ int dm_cache_get_free_metadata_block_cou
 	int r = -EINVAL;
 
 	READ_LOCK(cmd);
-	r = dm_sm_get_nr_free(cmd->metadata_sm, result);
+	if (!cmd->fail_io)
+		r = dm_sm_get_nr_free(cmd->metadata_sm, result);
 	READ_UNLOCK(cmd);
 
 	return r;
@@ -1360,7 +1363,8 @@ int dm_cache_get_metadata_dev_size(struc
 	int r = -EINVAL;
 
 	READ_LOCK(cmd);
-	r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
+	if (!cmd->fail_io)
+		r = dm_sm_get_nr_blocks(cmd->metadata_sm, result);
 	READ_UNLOCK(cmd);
 
 	return r;