Re: FAILED: patch "[PATCH] btrfs: handle logged extent failure properly" failed to apply to 5.6-stable tree

[Sasha Levin <sashal@kernel.org>]

On Thu, Apr 16, 2020 at 09:07:20AM +0200, Greg KH wrote:
>On Wed, Apr 15, 2020 at 08:41:54PM -0400, Sasha Levin wrote:
>> On Tue, Apr 14, 2020 at 04:21:45PM +0200, gregkh@linuxfoundation.org wrote:
>> >
>> > The patch below does not apply to the 5.6-stable tree.
>> > If someone wants it applied there, or to any other stable or longterm
>> > tree, then please email the backport, including the original git commit
>> > id to <stable@vger.kernel.org>.
>> >
>> > thanks,
>> >
>> > greg k-h
>> >
>> > ------------------ original commit in Linus's tree ------------------
>> >
>> > > From ab9b2c7b32e6be53cac2e23f5b2db66815a7d972 Mon Sep 17 00:00:00 2001
>> > From: Josef Bacik <josef@toxicpanda.com>
>> > Date: Thu, 13 Feb 2020 10:47:30 -0500
>> > Subject: [PATCH] btrfs: handle logged extent failure properly
>> >
>> > If we're allocating a logged extent we attempt to insert an extent
>> > record for the file extent directly.  We increase
>> > space_info->bytes_reserved, because the extent entry addition will call
>> > btrfs_update_block_group(), which will convert the ->bytes_reserved to
>> > ->bytes_used.  However if we fail at any point while inserting the
>> > extent entry we will bail and leave space on ->bytes_reserved, which
>> > will trigger a WARN_ON() on umount.  Fix this by pinning the space if we
>> > fail to insert, which is what happens in every other failure case that
>> > involves adding the extent entry.
>> >
>> > CC: stable@vger.kernel.org # 5.4+
>> > Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
>> > Reviewed-by: Nikolay Borisov <nborisov@suse.com>
>> > Reviewed-by: Qu Wenruo <wqu@suse.com>
>> > Signed-off-by: Josef Bacik <josef@toxicpanda.com>
>> > Reviewed-by: David Sterba <dsterba@suse.com>
>> > Signed-off-by: David Sterba <dsterba@suse.com>
>>
>> Greg, I've noticed that you've fixed it up for 5.5 and 5.4 but no for
>> 5.6? I've queued it up for 5.6 as well.
>
>I didn't include this in 5.5 or 5.4, so please queue it up in those two
>trees as well.

Hm, looking at the patch:

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a7bc66121330e..219ac9990513e 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4431,7 +4431,7 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
        ret = alloc_reserved_file_extent(trans, 0, root_objectid, 0, owner,
                                         offset, ins, 1);
        if (ret)
-               btrfs_pin_extent(fs_info, ins->objectid, ins->offset, 1);
+               btrfs_pin_extent(trans, ins->objectid, ins->offset, 1);
        btrfs_put_block_group(block_group);
        return ret;
 }

It changes the var and type used to call btrfs_pin_extent() without
changing the declaration of btrfs_pin_extent() itself - which is weird.

The change to btrfs_pin_extent() was done in b25c36f84b59 ("btrfs: Make
btrfs_pin_extent take trans handle"), but then I'm confused how this
patch on it's own fixes anything but a build issue - which makes the
commit message confusing :)

Maybe one of the btrfs folks could clarify?

-- 
Thanks,
Sasha