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

btrfs: Fix flush bio leak

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: btrfs-fix-flush-bio-leak.patch and it can be found in the queue-4.14 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 foo@baz Wed Feb 28 16:23:28 CET 2018

From: Nikolay Borisov nborisov@suse.com Date: Wed, 13 Dec 2017 13:50:07 +0200 Subject: btrfs: Fix flush bio leak

From: Nikolay Borisov nborisov@suse.com

[ Upstream commit beed9263f4000c48a5c48912f26576f6fa091181 ]

Commit e0ae99941423 ("btrfs: preallocate device flush bio") reworked the way the flush bio is allocated and used. Concretely it allocates the bio in __alloc_device and then re-uses it multiple times with a very simple endio routine that just calls complete() without consuming a reference. Allocated bios by default come with a ref count of 1, which is then consumed by the endio routine (or not, in which case they should be bio_put by the caller). The way the impleementation works now is that the flush bio has a refcount of 2 and we only ever bio_put it once, leaving it to hang indefinitely. Fix this by removing the extra bio_get in __alloc_device.

Fixes: e0ae99941423 ("btrfs: preallocate device flush bio") Signed-off-by: Nikolay Borisov nborisov@suse.com Reviewed-by: Liu Bo bo.li.liu@oracle.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/volumes.c | 1 - 1 file changed, 1 deletion(-)

--- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -236,7 +236,6 @@ static struct btrfs_device *__alloc_devi kfree(dev); return ERR_PTR(-ENOMEM); } - bio_get(dev->flush_bio);

INIT_LIST_HEAD(&dev->dev_list); INIT_LIST_HEAD(&dev->dev_alloc_list);

Patches currently in stable-queue which might be from nborisov@suse.com are

queue-4.14/btrfs-fix-flush-bio-leak.patch