Patch "dm thin metadata: don't issue prefetches if a transaction abort has failed" has been added to the 4.5-stable tree

[<gregkh@linuxfoundation.org>]

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

    dm thin metadata: don't issue prefetches if a transaction abort has failed

to the 4.5-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-thin-metadata-don-t-issue-prefetches-if-a-transaction-abort-has-failed.patch
and it can be found in the queue-4.5 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 2eae9e4489b4cf83213fa3bd508b5afca3f01780 Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt@redhat.com>
Date: Tue, 1 Mar 2016 10:58:44 +0000
Subject: dm thin metadata: don't issue prefetches if a transaction abort has failed

From: Joe Thornber <ejt@redhat.com>

commit 2eae9e4489b4cf83213fa3bd508b5afca3f01780 upstream.

If a transaction abort has failed then we can no longer use the metadata
device.  Typically this happens if the superblock is unreadable.

This fix addresses a crash seen during metadata device failure testing.

Fixes: 8a01a6af75 ("dm thin: prefetch missing metadata pages")
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-thin-metadata.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -1981,5 +1981,8 @@ bool dm_pool_metadata_needs_check(struct
 
 void dm_pool_issue_prefetches(struct dm_pool_metadata *pmd)
 {
-	dm_tm_issue_prefetches(pmd->tm);
+	down_read(&pmd->root_lock);
+	if (!pmd->fail_io)
+		dm_tm_issue_prefetches(pmd->tm);
+	up_read(&pmd->root_lock);
 }


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

queue-4.5/dm-thin-metadata-don-t-issue-prefetches-if-a-transaction-abort-has-failed.patch
queue-4.5/dm-cache-make-sure-every-metadata-function-checks-fail_io.patch