Patch "dm cache: the CLEAN_SHUTDOWN flag was not being set" has been added to the 4.2-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    dm cache: the CLEAN_SHUTDOWN flag was not being set

to the 4.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     dm-cache-the-clean_shutdown-flag-was-not-being-set.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 3201ac452e84a8a368197d648c9b7011e061804a Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt@redhat.com>
Date: Thu, 22 Oct 2015 18:10:55 +0100
Subject: dm cache: the CLEAN_SHUTDOWN flag was not being set

From: Joe Thornber <ejt@redhat.com>

commit 3201ac452e84a8a368197d648c9b7011e061804a upstream.

If the CLEAN_SHUTDOWN flag is not set when a cache is loaded then all cache
blocks are marked as dirty and a full writeback occurs.

__commit_transaction() is responsible for setting/clearing
CLEAN_SHUTDOWN (based the flags_mutator that is passed in).

Fix this issue, of the cache's on-disk flags being wrong, by making sure
__commit_transaction() does not reset the flags after the mutator has
altered the flags in preparation for them being serialized to disk.

before:

sb_flags = mutator(le32_to_cpu(disk_super->flags));
disk_super->flags = cpu_to_le32(sb_flags);
disk_super->flags = cpu_to_le32(cmd->flags);

after:

disk_super->flags = cpu_to_le32(cmd->flags);
sb_flags = mutator(le32_to_cpu(disk_super->flags));
disk_super->flags = cpu_to_le32(sb_flags);

Reported-by: Bogdan Vasiliev <bogdan.vasiliev@gmail.com>
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/md/dm-cache-metadata.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -634,10 +634,10 @@ static int __commit_transaction(struct d
 
 	disk_super = dm_block_data(sblock);
 
+	disk_super->flags = cpu_to_le32(cmd->flags);
 	if (mutator)
 		update_flags(disk_super, mutator);
 
-	disk_super->flags = cpu_to_le32(cmd->flags);
 	disk_super->mapping_root = cpu_to_le64(cmd->root);
 	disk_super->hint_root = cpu_to_le64(cmd->hint_root);
 	disk_super->discard_root = cpu_to_le64(cmd->discard_root);


Patches currently in stable-queue which might be from ejt@redhat.com are

queue-4.2/dm-btree-remove-fix-a-bug-when-rebalancing-nodes-after-removal.patch
queue-4.2/dm-cache-the-clean_shutdown-flag-was-not-being-set.patch